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29960 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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ffserver Documentation
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<h1>
ffserver Documentation
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<a name="SEC_Top"></a>
<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>
<div class="contents">
<ul class="no-bullet">
<li><a name="toc-Synopsis" href="#Synopsis">1 Synopsis</a></li>
<li><a name="toc-Description" href="#Description">2 Description</a></li>
<li><a name="toc-Detailed-description" href="#Detailed-description">3 Detailed description</a>
<ul class="no-bullet">
<li><a name="toc-FFM_002c-FFM2-formats" href="#FFM_002c-FFM2-formats">3.1 FFM, FFM2 formats</a></li>
<li><a name="toc-Status-stream" href="#Status-stream">3.2 Status stream</a></li>
<li><a name="toc-How-do-I-make-it-work_003f" href="#How-do-I-make-it-work_003f">3.3 How do I make it work?</a></li>
<li><a name="toc-What-else-can-it-do_003f" href="#What-else-can-it-do_003f">3.4 What else can it do?</a></li>
<li><a name="toc-Tips" href="#Tips">3.5 Tips</a></li>
<li><a name="toc-Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f" href="#Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f">3.6 Why does the ?buffer / Preroll stop working after a time?</a></li>
<li><a name="toc-Does-the-_003fdate_003d-stuff-work_002e" href="#Does-the-_003fdate_003d-stuff-work_002e">3.7 Does the <code>?date=</code> stuff work.</a></li>
</ul></li>
<li><a name="toc-Options" href="#Options">4 Options</a>
<ul class="no-bullet">
<li><a name="toc-Stream-specifiers-1" href="#Stream-specifiers-1">4.1 Stream specifiers</a></li>
<li><a name="toc-Generic-options" href="#Generic-options">4.2 Generic options</a></li>
<li><a name="toc-AVOptions" href="#AVOptions">4.3 AVOptions</a></li>
<li><a name="toc-Main-options" href="#Main-options">4.4 Main options</a></li>
</ul></li>
<li><a name="toc-Configuration-file-syntax" href="#Configuration-file-syntax">5 Configuration file syntax</a>
<ul class="no-bullet">
<li><a name="toc-ACL-syntax" href="#ACL-syntax">5.1 ACL syntax</a></li>
<li><a name="toc-Global-options" href="#Global-options">5.2 Global options</a></li>
<li><a name="toc-Feed-section" href="#Feed-section">5.3 Feed section</a></li>
<li><a name="toc-Stream-section" href="#Stream-section">5.4 Stream section</a>
<ul class="no-bullet">
<li><a name="toc-Server-status-stream" href="#Server-status-stream">5.4.1 Server status stream</a></li>
</ul></li>
<li><a name="toc-Redirect-section" href="#Redirect-section">5.5 Redirect section</a></li>
</ul></li>
<li><a name="toc-Stream-examples" href="#Stream-examples">6 Stream examples</a></li>
<li><a name="toc-Syntax" href="#Syntax">7 Syntax</a>
<ul class="no-bullet">
<li><a name="toc-Quoting-and-escaping" href="#Quoting-and-escaping">7.1 Quoting and escaping</a>
<ul class="no-bullet">
<li><a name="toc-Examples" href="#Examples">7.1.1 Examples</a></li>
</ul></li>
<li><a name="toc-Date" href="#Date">7.2 Date</a></li>
<li><a name="toc-Time-duration" href="#Time-duration">7.3 Time duration</a>
<ul class="no-bullet">
<li><a name="toc-Examples-1" href="#Examples-1">7.3.1 Examples</a></li>
</ul></li>
<li><a name="toc-Video-size" href="#Video-size">7.4 Video size</a></li>
<li><a name="toc-Video-rate" href="#Video-rate">7.5 Video rate</a></li>
<li><a name="toc-Ratio" href="#Ratio">7.6 Ratio</a></li>
<li><a name="toc-Color" href="#Color">7.7 Color</a></li>
<li><a name="toc-Channel-Layout" href="#Channel-Layout">7.8 Channel Layout</a></li>
</ul></li>
<li><a name="toc-Expression-Evaluation" href="#Expression-Evaluation">8 Expression Evaluation</a></li>
<li><a name="toc-OpenCL-Options" href="#OpenCL-Options">9 OpenCL Options</a></li>
<li><a name="toc-Codec-Options" href="#Codec-Options">10 Codec Options</a></li>
<li><a name="toc-Decoders" href="#Decoders">11 Decoders</a></li>
<li><a name="toc-Video-Decoders" href="#Video-Decoders">12 Video Decoders</a>
<ul class="no-bullet">
<li><a name="toc-hevc" href="#hevc">12.1 hevc</a></li>
<li><a name="toc-rawvideo" href="#rawvideo">12.2 rawvideo</a>
<ul class="no-bullet">
<li><a name="toc-Options-1" href="#Options-1">12.2.1 Options</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Audio-Decoders" href="#Audio-Decoders">13 Audio Decoders</a>
<ul class="no-bullet">
<li><a name="toc-ac3" href="#ac3">13.1 ac3</a>
<ul class="no-bullet">
<li><a name="toc-AC_002d3-Decoder-Options" href="#AC_002d3-Decoder-Options">13.1.1 AC-3 Decoder Options</a></li>
</ul></li>
<li><a name="toc-flac-1" href="#flac-1">13.2 flac</a>
<ul class="no-bullet">
<li><a name="toc-FLAC-Decoder-options" href="#FLAC-Decoder-options">13.2.1 FLAC Decoder options</a></li>
</ul></li>
<li><a name="toc-ffwavesynth" href="#ffwavesynth">13.3 ffwavesynth</a></li>
<li><a name="toc-libcelt" href="#libcelt">13.4 libcelt</a></li>
<li><a name="toc-libgsm" href="#libgsm">13.5 libgsm</a></li>
<li><a name="toc-libilbc" href="#libilbc">13.6 libilbc</a>
<ul class="no-bullet">
<li><a name="toc-Options-2" href="#Options-2">13.6.1 Options</a></li>
</ul></li>
<li><a name="toc-libopencore_002damrnb" href="#libopencore_002damrnb">13.7 libopencore-amrnb</a></li>
<li><a name="toc-libopencore_002damrwb" href="#libopencore_002damrwb">13.8 libopencore-amrwb</a></li>
<li><a name="toc-libopus" href="#libopus">13.9 libopus</a></li>
</ul></li>
<li><a name="toc-Subtitles-Decoders" href="#Subtitles-Decoders">14 Subtitles Decoders</a>
<ul class="no-bullet">
<li><a name="toc-dvbsub" href="#dvbsub">14.1 dvbsub</a>
<ul class="no-bullet">
<li><a name="toc-Options-3" href="#Options-3">14.1.1 Options</a></li>
</ul></li>
<li><a name="toc-dvdsub" href="#dvdsub">14.2 dvdsub</a>
<ul class="no-bullet">
<li><a name="toc-Options-4" href="#Options-4">14.2.1 Options</a></li>
</ul></li>
<li><a name="toc-libzvbi_002dteletext" href="#libzvbi_002dteletext">14.3 libzvbi-teletext</a>
<ul class="no-bullet">
<li><a name="toc-Options-5" href="#Options-5">14.3.1 Options</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Encoders" href="#Encoders">15 Encoders</a></li>
<li><a name="toc-Audio-Encoders" href="#Audio-Encoders">16 Audio Encoders</a>
<ul class="no-bullet">
<li><a name="toc-aac" href="#aac">16.1 aac</a>
<ul class="no-bullet">
<li><a name="toc-Options-6" href="#Options-6">16.1.1 Options</a></li>
</ul></li>
<li><a name="toc-ac3-and-ac3_005ffixed" href="#ac3-and-ac3_005ffixed">16.2 ac3 and ac3_fixed</a>
<ul class="no-bullet">
<li><a name="toc-AC_002d3-Metadata" href="#AC_002d3-Metadata">16.2.1 AC-3 Metadata</a>
<ul class="no-bullet">
<li><a name="toc-Metadata-Control-Options" href="#Metadata-Control-Options">16.2.1.1 Metadata Control Options</a></li>
<li><a name="toc-Downmix-Levels" href="#Downmix-Levels">16.2.1.2 Downmix Levels</a></li>
<li><a name="toc-Audio-Production-Information" href="#Audio-Production-Information">16.2.1.3 Audio Production Information</a></li>
<li><a name="toc-Other-Metadata-Options" href="#Other-Metadata-Options">16.2.1.4 Other Metadata Options</a></li>
</ul></li>
<li><a name="toc-Extended-Bitstream-Information" href="#Extended-Bitstream-Information">16.2.2 Extended Bitstream Information</a>
<ul class="no-bullet">
<li><a name="toc-Extended-Bitstream-Information-_002d-Part-1" href="#Extended-Bitstream-Information-_002d-Part-1">16.2.2.1 Extended Bitstream Information - Part 1</a></li>
<li><a name="toc-Extended-Bitstream-Information-_002d-Part-2" href="#Extended-Bitstream-Information-_002d-Part-2">16.2.2.2 Extended Bitstream Information - Part 2</a></li>
</ul></li>
<li><a name="toc-Other-AC_002d3-Encoding-Options" href="#Other-AC_002d3-Encoding-Options">16.2.3 Other AC-3 Encoding Options</a></li>
<li><a name="toc-Floating_002dPoint_002dOnly-AC_002d3-Encoding-Options" href="#Floating_002dPoint_002dOnly-AC_002d3-Encoding-Options">16.2.4 Floating-Point-Only AC-3 Encoding Options</a></li>
</ul></li>
<li><a name="toc-flac-2" href="#flac-2">16.3 flac</a>
<ul class="no-bullet">
<li><a name="toc-Options-7" href="#Options-7">16.3.1 Options</a></li>
</ul></li>
<li><a name="toc-libfaac-1" href="#libfaac-1">16.4 libfaac</a>
<ul class="no-bullet">
<li><a name="toc-Options-8" href="#Options-8">16.4.1 Options</a></li>
<li><a name="toc-Examples-2" href="#Examples-2">16.4.2 Examples</a></li>
</ul></li>
<li><a name="toc-libfdk_005faac" href="#libfdk_005faac">16.5 libfdk_aac</a>
<ul class="no-bullet">
<li><a name="toc-Options-9" href="#Options-9">16.5.1 Options</a></li>
<li><a name="toc-Examples-3" href="#Examples-3">16.5.2 Examples</a></li>
</ul></li>
<li><a name="toc-libmp3lame-1" href="#libmp3lame-1">16.6 libmp3lame</a>
<ul class="no-bullet">
<li><a name="toc-Options-10" href="#Options-10">16.6.1 Options</a></li>
</ul></li>
<li><a name="toc-libopencore_002damrnb-1" href="#libopencore_002damrnb-1">16.7 libopencore-amrnb</a>
<ul class="no-bullet">
<li><a name="toc-Options-11" href="#Options-11">16.7.1 Options</a></li>
</ul></li>
<li><a name="toc-libshine-1" href="#libshine-1">16.8 libshine</a>
<ul class="no-bullet">
<li><a name="toc-Options-12" href="#Options-12">16.8.1 Options</a></li>
</ul></li>
<li><a name="toc-libtwolame" href="#libtwolame">16.9 libtwolame</a>
<ul class="no-bullet">
<li><a name="toc-Options-13" href="#Options-13">16.9.1 Options</a></li>
</ul></li>
<li><a name="toc-libvo_002daacenc-1" href="#libvo_002daacenc-1">16.10 libvo-aacenc</a>
<ul class="no-bullet">
<li><a name="toc-Options-14" href="#Options-14">16.10.1 Options</a></li>
</ul></li>
<li><a name="toc-libvo_002damrwbenc" href="#libvo_002damrwbenc">16.11 libvo-amrwbenc</a>
<ul class="no-bullet">
<li><a name="toc-Options-15" href="#Options-15">16.11.1 Options</a></li>
</ul></li>
<li><a name="toc-libopus-1" href="#libopus-1">16.12 libopus</a>
<ul class="no-bullet">
<li><a name="toc-Option-Mapping" href="#Option-Mapping">16.12.1 Option Mapping</a></li>
</ul></li>
<li><a name="toc-libvorbis" href="#libvorbis">16.13 libvorbis</a>
<ul class="no-bullet">
<li><a name="toc-Options-16" href="#Options-16">16.13.1 Options</a></li>
</ul></li>
<li><a name="toc-libwavpack-1" href="#libwavpack-1">16.14 libwavpack</a>
<ul class="no-bullet">
<li><a name="toc-Options-17" href="#Options-17">16.14.1 Options</a></li>
</ul></li>
<li><a name="toc-wavpack" href="#wavpack">16.15 wavpack</a>
<ul class="no-bullet">
<li><a name="toc-Options-18" href="#Options-18">16.15.1 Options</a>
<ul class="no-bullet">
<li><a name="toc-Shared-options" href="#Shared-options">16.15.1.1 Shared options</a></li>
<li><a name="toc-Private-options" href="#Private-options">16.15.1.2 Private options</a></li>
</ul></li>
</ul></li>
</ul></li>
<li><a name="toc-Video-Encoders" href="#Video-Encoders">17 Video Encoders</a>
<ul class="no-bullet">
<li><a name="toc-jpeg2000" href="#jpeg2000">17.1 jpeg2000</a>
<ul class="no-bullet">
<li><a name="toc-Options-19" href="#Options-19">17.1.1 Options</a></li>
</ul></li>
<li><a name="toc-snow" href="#snow">17.2 snow</a>
<ul class="no-bullet">
<li><a name="toc-Options-20" href="#Options-20">17.2.1 Options</a></li>
</ul></li>
<li><a name="toc-libtheora" href="#libtheora">17.3 libtheora</a>
<ul class="no-bullet">
<li><a name="toc-Options-21" href="#Options-21">17.3.1 Options</a></li>
<li><a name="toc-Examples-4" href="#Examples-4">17.3.2 Examples</a></li>
</ul></li>
<li><a name="toc-libvpx" href="#libvpx">17.4 libvpx</a>
<ul class="no-bullet">
<li><a name="toc-Options-22" href="#Options-22">17.4.1 Options</a></li>
</ul></li>
<li><a name="toc-libwebp" href="#libwebp">17.5 libwebp</a>
<ul class="no-bullet">
<li><a name="toc-Pixel-Format" href="#Pixel-Format">17.5.1 Pixel Format</a></li>
<li><a name="toc-Options-23" href="#Options-23">17.5.2 Options</a></li>
</ul></li>
<li><a name="toc-libx264_002c-libx264rgb" href="#libx264_002c-libx264rgb">17.6 libx264, libx264rgb</a>
<ul class="no-bullet">
<li><a name="toc-Supported-Pixel-Formats" href="#Supported-Pixel-Formats">17.6.1 Supported Pixel Formats</a></li>
<li><a name="toc-Options-24" href="#Options-24">17.6.2 Options</a></li>
</ul></li>
<li><a name="toc-libx265" href="#libx265">17.7 libx265</a>
<ul class="no-bullet">
<li><a name="toc-Options-25" href="#Options-25">17.7.1 Options</a></li>
</ul></li>
<li><a name="toc-libxvid" href="#libxvid">17.8 libxvid</a>
<ul class="no-bullet">
<li><a name="toc-Options-26" href="#Options-26">17.8.1 Options</a></li>
</ul></li>
<li><a name="toc-mpeg2" href="#mpeg2">17.9 mpeg2</a>
<ul class="no-bullet">
<li><a name="toc-Options-27" href="#Options-27">17.9.1 Options</a></li>
</ul></li>
<li><a name="toc-png" href="#png">17.10 png</a>
<ul class="no-bullet">
<li><a name="toc-Private-options-1" href="#Private-options-1">17.10.1 Private options</a></li>
</ul></li>
<li><a name="toc-ProRes" href="#ProRes">17.11 ProRes</a>
<ul class="no-bullet">
<li><a name="toc-Private-Options-for-prores_002dks" href="#Private-Options-for-prores_002dks">17.11.1 Private Options for prores-ks</a></li>
<li><a name="toc-Speed-considerations" href="#Speed-considerations">17.11.2 Speed considerations</a></li>
</ul></li>
<li><a name="toc-libkvazaar" href="#libkvazaar">17.12 libkvazaar</a>
<ul class="no-bullet">
<li><a name="toc-Options-28" href="#Options-28">17.12.1 Options</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Subtitles-Encoders" href="#Subtitles-Encoders">18 Subtitles Encoders</a>
<ul class="no-bullet">
<li><a name="toc-dvdsub-1" href="#dvdsub-1">18.1 dvdsub</a>
<ul class="no-bullet">
<li><a name="toc-Options-29" href="#Options-29">18.1.1 Options</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Bitstream-Filters" href="#Bitstream-Filters">19 Bitstream Filters</a>
<ul class="no-bullet">
<li><a name="toc-aac_005fadtstoasc" href="#aac_005fadtstoasc">19.1 aac_adtstoasc</a></li>
<li><a name="toc-chomp" href="#chomp">19.2 chomp</a></li>
<li><a name="toc-dump_005fextra" href="#dump_005fextra">19.3 dump_extra</a></li>
<li><a name="toc-h264_005fmp4toannexb" href="#h264_005fmp4toannexb">19.4 h264_mp4toannexb</a></li>
<li><a name="toc-imxdump" href="#imxdump">19.5 imxdump</a></li>
<li><a name="toc-mjpeg2jpeg" href="#mjpeg2jpeg">19.6 mjpeg2jpeg</a></li>
<li><a name="toc-mjpega_005fdump_005fheader" href="#mjpega_005fdump_005fheader">19.7 mjpega_dump_header</a></li>
<li><a name="toc-movsub" href="#movsub">19.8 movsub</a></li>
<li><a name="toc-mp3_005fheader_005fdecompress" href="#mp3_005fheader_005fdecompress">19.9 mp3_header_decompress</a></li>
<li><a name="toc-mpeg4_005funpack_005fbframes" href="#mpeg4_005funpack_005fbframes">19.10 mpeg4_unpack_bframes</a></li>
<li><a name="toc-noise" href="#noise">19.11 noise</a></li>
<li><a name="toc-remove_005fextra" href="#remove_005fextra">19.12 remove_extra</a></li>
</ul></li>
<li><a name="toc-Format-Options" href="#Format-Options">20 Format Options</a>
<ul class="no-bullet">
<li><a name="toc-Format-stream-specifiers-1" href="#Format-stream-specifiers-1">20.1 Format stream specifiers</a></li>
</ul></li>
<li><a name="toc-Demuxers" href="#Demuxers">21 Demuxers</a>
<ul class="no-bullet">
<li><a name="toc-aa" href="#aa">21.1 aa</a></li>
<li><a name="toc-applehttp" href="#applehttp">21.2 applehttp</a></li>
<li><a name="toc-apng" href="#apng">21.3 apng</a></li>
<li><a name="toc-asf" href="#asf">21.4 asf</a></li>
<li><a name="toc-concat-1" href="#concat-1">21.5 concat</a>
<ul class="no-bullet">
<li><a name="toc-Syntax-1" href="#Syntax-1">21.5.1 Syntax</a></li>
<li><a name="toc-Options-30" href="#Options-30">21.5.2 Options</a></li>
</ul></li>
<li><a name="toc-flv" href="#flv">21.6 flv</a></li>
<li><a name="toc-libgme" href="#libgme">21.7 libgme</a></li>
<li><a name="toc-libquvi" href="#libquvi">21.8 libquvi</a></li>
<li><a name="toc-gif-1" href="#gif-1">21.9 gif</a></li>
<li><a name="toc-image2-1" href="#image2-1">21.10 image2</a>
<ul class="no-bullet">
<li><a name="toc-Examples-5" href="#Examples-5">21.10.1 Examples</a></li>
</ul></li>
<li><a name="toc-mov_002fmp4_002f3gp_002fQuicktme" href="#mov_002fmp4_002f3gp_002fQuicktme">21.11 mov/mp4/3gp/Quicktme</a></li>
<li><a name="toc-mpegts" href="#mpegts">21.12 mpegts</a></li>
<li><a name="toc-rawvideo-1" href="#rawvideo-1">21.13 rawvideo</a></li>
<li><a name="toc-sbg" href="#sbg">21.14 sbg</a></li>
<li><a name="toc-tedcaptions" href="#tedcaptions">21.15 tedcaptions</a></li>
</ul></li>
<li><a name="toc-Muxers" href="#Muxers">22 Muxers</a>
<ul class="no-bullet">
<li><a name="toc-aiff-1" href="#aiff-1">22.1 aiff</a>
<ul class="no-bullet">
<li><a name="toc-Options-31" href="#Options-31">22.1.1 Options</a></li>
</ul></li>
<li><a name="toc-crc-1" href="#crc-1">22.2 crc</a>
<ul class="no-bullet">
<li><a name="toc-Examples-6" href="#Examples-6">22.2.1 Examples</a></li>
</ul></li>
<li><a name="toc-framecrc-1" href="#framecrc-1">22.3 framecrc</a>
<ul class="no-bullet">
<li><a name="toc-Examples-7" href="#Examples-7">22.3.1 Examples</a></li>
</ul></li>
<li><a name="toc-framemd5-1" href="#framemd5-1">22.4 framemd5</a>
<ul class="no-bullet">
<li><a name="toc-Examples-8" href="#Examples-8">22.4.1 Examples</a></li>
</ul></li>
<li><a name="toc-gif-2" href="#gif-2">22.5 gif</a></li>
<li><a name="toc-hls-1" href="#hls-1">22.6 hls</a>
<ul class="no-bullet">
<li><a name="toc-Options-32" href="#Options-32">22.6.1 Options</a></li>
</ul></li>
<li><a name="toc-ico-1" href="#ico-1">22.7 ico</a></li>
<li><a name="toc-image2-2" href="#image2-2">22.8 image2</a>
<ul class="no-bullet">
<li><a name="toc-Examples-9" href="#Examples-9">22.8.1 Examples</a></li>
<li><a name="toc-Options-33" href="#Options-33">22.8.2 Options</a></li>
</ul></li>
<li><a name="toc-matroska" href="#matroska">22.9 matroska</a>
<ul class="no-bullet">
<li><a name="toc-Metadata" href="#Metadata">22.9.1 Metadata</a></li>
<li><a name="toc-Options-34" href="#Options-34">22.9.2 Options</a></li>
</ul></li>
<li><a name="toc-md5-1" href="#md5-1">22.10 md5</a></li>
<li><a name="toc-mov_002c-mp4_002c-ismv" href="#mov_002c-mp4_002c-ismv">22.11 mov, mp4, ismv</a>
<ul class="no-bullet">
<li><a name="toc-Options-35" href="#Options-35">22.11.1 Options</a></li>
<li><a name="toc-Example" href="#Example">22.11.2 Example</a></li>
<li><a name="toc-Audible-AAX" href="#Audible-AAX">22.11.3 Audible AAX</a></li>
</ul></li>
<li><a name="toc-mp3" href="#mp3">22.12 mp3</a></li>
<li><a name="toc-mpegts-1" href="#mpegts-1">22.13 mpegts</a>
<ul class="no-bullet">
<li><a name="toc-Options-36" href="#Options-36">22.13.1 Options</a></li>
<li><a name="toc-Example-1" href="#Example-1">22.13.2 Example</a></li>
</ul></li>
<li><a name="toc-mxf_002c-mxf_005fd10" href="#mxf_002c-mxf_005fd10">22.14 mxf, mxf_d10</a>
<ul class="no-bullet">
<li><a name="toc-Options-37" href="#Options-37">22.14.1 Options</a></li>
</ul></li>
<li><a name="toc-null" href="#null">22.15 null</a></li>
<li><a name="toc-nut" href="#nut">22.16 nut</a></li>
<li><a name="toc-ogg" href="#ogg">22.17 ogg</a></li>
<li><a name="toc-segment_002c-stream_005fsegment_002c-ssegment" href="#segment_002c-stream_005fsegment_002c-ssegment">22.18 segment, stream_segment, ssegment</a>
<ul class="no-bullet">
<li><a name="toc-Options-38" href="#Options-38">22.18.1 Options</a></li>
<li><a name="toc-Examples-10" href="#Examples-10">22.18.2 Examples</a></li>
</ul></li>
<li><a name="toc-smoothstreaming" href="#smoothstreaming">22.19 smoothstreaming</a></li>
<li><a name="toc-tee" href="#tee">22.20 tee</a>
<ul class="no-bullet">
<li><a name="toc-Examples-11" href="#Examples-11">22.20.1 Examples</a></li>
</ul></li>
<li><a name="toc-webm_005fdash_005fmanifest" href="#webm_005fdash_005fmanifest">22.21 webm_dash_manifest</a>
<ul class="no-bullet">
<li><a name="toc-Options-39" href="#Options-39">22.21.1 Options</a></li>
<li><a name="toc-Example-2" href="#Example-2">22.21.2 Example</a></li>
</ul></li>
<li><a name="toc-webm_005fchunk" href="#webm_005fchunk">22.22 webm_chunk</a>
<ul class="no-bullet">
<li><a name="toc-Options-40" href="#Options-40">22.22.1 Options</a></li>
<li><a name="toc-Example-3" href="#Example-3">22.22.2 Example</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Metadata-1" href="#Metadata-1">23 Metadata</a></li>
<li><a name="toc-Protocols" href="#Protocols">24 Protocols</a>
<ul class="no-bullet">
<li><a name="toc-async" href="#async">24.1 async</a></li>
<li><a name="toc-bluray" href="#bluray">24.2 bluray</a></li>
<li><a name="toc-cache" href="#cache">24.3 cache</a></li>
<li><a name="toc-concat-2" href="#concat-2">24.4 concat</a></li>
<li><a name="toc-crypto" href="#crypto">24.5 crypto</a></li>
<li><a name="toc-data" href="#data">24.6 data</a></li>
<li><a name="toc-file" href="#file">24.7 file</a></li>
<li><a name="toc-ftp" href="#ftp">24.8 ftp</a></li>
<li><a name="toc-gopher" href="#gopher">24.9 gopher</a></li>
<li><a name="toc-hls-2" href="#hls-2">24.10 hls</a></li>
<li><a name="toc-http" href="#http">24.11 http</a>
<ul class="no-bullet">
<li><a name="toc-HTTP-Cookies" href="#HTTP-Cookies">24.11.1 HTTP Cookies</a></li>
</ul></li>
<li><a name="toc-Icecast" href="#Icecast">24.12 Icecast</a></li>
<li><a name="toc-mmst" href="#mmst">24.13 mmst</a></li>
<li><a name="toc-mmsh" href="#mmsh">24.14 mmsh</a></li>
<li><a name="toc-md5-2" href="#md5-2">24.15 md5</a></li>
<li><a name="toc-pipe" href="#pipe">24.16 pipe</a></li>
<li><a name="toc-rtmp" href="#rtmp">24.17 rtmp</a></li>
<li><a name="toc-rtmpe" href="#rtmpe">24.18 rtmpe</a></li>
<li><a name="toc-rtmps" href="#rtmps">24.19 rtmps</a></li>
<li><a name="toc-rtmpt" href="#rtmpt">24.20 rtmpt</a></li>
<li><a name="toc-rtmpte" href="#rtmpte">24.21 rtmpte</a></li>
<li><a name="toc-rtmpts" href="#rtmpts">24.22 rtmpts</a></li>
<li><a name="toc-libsmbclient" href="#libsmbclient">24.23 libsmbclient</a></li>
<li><a name="toc-libssh" href="#libssh">24.24 libssh</a></li>
<li><a name="toc-librtmp-rtmp_002c-rtmpe_002c-rtmps_002c-rtmpt_002c-rtmpte" href="#librtmp-rtmp_002c-rtmpe_002c-rtmps_002c-rtmpt_002c-rtmpte">24.25 librtmp rtmp, rtmpe, rtmps, rtmpt, rtmpte</a></li>
<li><a name="toc-rtp" href="#rtp">24.26 rtp</a></li>
<li><a name="toc-rtsp" href="#rtsp">24.27 rtsp</a>
<ul class="no-bullet">
<li><a name="toc-Examples-12" href="#Examples-12">24.27.1 Examples</a></li>
</ul></li>
<li><a name="toc-sap" href="#sap">24.28 sap</a>
<ul class="no-bullet">
<li><a name="toc-Muxer" href="#Muxer">24.28.1 Muxer</a></li>
<li><a name="toc-Demuxer" href="#Demuxer">24.28.2 Demuxer</a></li>
</ul></li>
<li><a name="toc-sctp" href="#sctp">24.29 sctp</a></li>
<li><a name="toc-srtp" href="#srtp">24.30 srtp</a></li>
<li><a name="toc-subfile" href="#subfile">24.31 subfile</a></li>
<li><a name="toc-tcp" href="#tcp">24.32 tcp</a></li>
<li><a name="toc-tls" href="#tls">24.33 tls</a></li>
<li><a name="toc-udp" href="#udp">24.34 udp</a>
<ul class="no-bullet">
<li><a name="toc-Examples-13" href="#Examples-13">24.34.1 Examples</a></li>
</ul></li>
<li><a name="toc-unix" href="#unix">24.35 unix</a></li>
</ul></li>
<li><a name="toc-Device-Options" href="#Device-Options">25 Device Options</a></li>
<li><a name="toc-Input-Devices" href="#Input-Devices">26 Input Devices</a>
<ul class="no-bullet">
<li><a name="toc-alsa" href="#alsa">26.1 alsa</a>
<ul class="no-bullet">
<li><a name="toc-Options-41" href="#Options-41">26.1.1 Options</a></li>
</ul></li>
<li><a name="toc-avfoundation" href="#avfoundation">26.2 avfoundation</a>
<ul class="no-bullet">
<li><a name="toc-Options-42" href="#Options-42">26.2.1 Options</a></li>
<li><a name="toc-Examples-14" href="#Examples-14">26.2.2 Examples</a></li>
</ul></li>
<li><a name="toc-bktr" href="#bktr">26.3 bktr</a>
<ul class="no-bullet">
<li><a name="toc-Options-43" href="#Options-43">26.3.1 Options</a></li>
</ul></li>
<li><a name="toc-decklink" href="#decklink">26.4 decklink</a>
<ul class="no-bullet">
<li><a name="toc-Options-44" href="#Options-44">26.4.1 Options</a></li>
<li><a name="toc-Examples-15" href="#Examples-15">26.4.2 Examples</a></li>
</ul></li>
<li><a name="toc-dshow" href="#dshow">26.5 dshow</a>
<ul class="no-bullet">
<li><a name="toc-Options-45" href="#Options-45">26.5.1 Options</a></li>
<li><a name="toc-Examples-16" href="#Examples-16">26.5.2 Examples</a></li>
</ul></li>
<li><a name="toc-dv1394" href="#dv1394">26.6 dv1394</a>
<ul class="no-bullet">
<li><a name="toc-Options-46" href="#Options-46">26.6.1 Options</a></li>
</ul></li>
<li><a name="toc-fbdev" href="#fbdev">26.7 fbdev</a>
<ul class="no-bullet">
<li><a name="toc-Options-47" href="#Options-47">26.7.1 Options</a></li>
</ul></li>
<li><a name="toc-gdigrab" href="#gdigrab">26.8 gdigrab</a>
<ul class="no-bullet">
<li><a name="toc-Options-48" href="#Options-48">26.8.1 Options</a></li>
</ul></li>
<li><a name="toc-iec61883" href="#iec61883">26.9 iec61883</a>
<ul class="no-bullet">
<li><a name="toc-Options-49" href="#Options-49">26.9.1 Options</a></li>
<li><a name="toc-Examples-17" href="#Examples-17">26.9.2 Examples</a></li>
</ul></li>
<li><a name="toc-jack" href="#jack">26.10 jack</a>
<ul class="no-bullet">
<li><a name="toc-Options-50" href="#Options-50">26.10.1 Options</a></li>
</ul></li>
<li><a name="toc-lavfi" href="#lavfi">26.11 lavfi</a>
<ul class="no-bullet">
<li><a name="toc-Options-51" href="#Options-51">26.11.1 Options</a></li>
<li><a name="toc-Examples-18" href="#Examples-18">26.11.2 Examples</a></li>
</ul></li>
<li><a name="toc-libcdio" href="#libcdio">26.12 libcdio</a>
<ul class="no-bullet">
<li><a name="toc-Options-52" href="#Options-52">26.12.1 Options</a></li>
</ul></li>
<li><a name="toc-libdc1394" href="#libdc1394">26.13 libdc1394</a></li>
<li><a name="toc-openal" href="#openal">26.14 openal</a>
<ul class="no-bullet">
<li><a name="toc-Options-53" href="#Options-53">26.14.1 Options</a></li>
<li><a name="toc-Examples-19" href="#Examples-19">26.14.2 Examples</a></li>
</ul></li>
<li><a name="toc-oss" href="#oss">26.15 oss</a>
<ul class="no-bullet">
<li><a name="toc-Options-54" href="#Options-54">26.15.1 Options</a></li>
</ul></li>
<li><a name="toc-pulse" href="#pulse">26.16 pulse</a>
<ul class="no-bullet">
<li><a name="toc-Options-55" href="#Options-55">26.16.1 Options</a></li>
<li><a name="toc-Examples-20" href="#Examples-20">26.16.2 Examples</a></li>
</ul></li>
<li><a name="toc-qtkit" href="#qtkit">26.17 qtkit</a>
<ul class="no-bullet">
<li><a name="toc-Options-56" href="#Options-56">26.17.1 Options</a></li>
</ul></li>
<li><a name="toc-sndio" href="#sndio">26.18 sndio</a>
<ul class="no-bullet">
<li><a name="toc-Options-57" href="#Options-57">26.18.1 Options</a></li>
</ul></li>
<li><a name="toc-video4linux2_002c-v4l2" href="#video4linux2_002c-v4l2">26.19 video4linux2, v4l2</a>
<ul class="no-bullet">
<li><a name="toc-Options-58" href="#Options-58">26.19.1 Options</a></li>
</ul></li>
<li><a name="toc-vfwcap" href="#vfwcap">26.20 vfwcap</a>
<ul class="no-bullet">
<li><a name="toc-Options-59" href="#Options-59">26.20.1 Options</a></li>
</ul></li>
<li><a name="toc-x11grab" href="#x11grab">26.21 x11grab</a>
<ul class="no-bullet">
<li><a name="toc-Options-60" href="#Options-60">26.21.1 Options</a></li>
<li><a name="toc-grab_005fx-grab_005fy-AVOption" href="#grab_005fx-grab_005fy-AVOption">26.21.2 <var>grab_x</var> <var>grab_y</var> AVOption</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Output-Devices" href="#Output-Devices">27 Output Devices</a>
<ul class="no-bullet">
<li><a name="toc-alsa-1" href="#alsa-1">27.1 alsa</a>
<ul class="no-bullet">
<li><a name="toc-Examples-21" href="#Examples-21">27.1.1 Examples</a></li>
</ul></li>
<li><a name="toc-caca" href="#caca">27.2 caca</a>
<ul class="no-bullet">
<li><a name="toc-Options-61" href="#Options-61">27.2.1 Options</a></li>
<li><a name="toc-Examples-22" href="#Examples-22">27.2.2 Examples</a></li>
</ul></li>
<li><a name="toc-decklink-1" href="#decklink-1">27.3 decklink</a>
<ul class="no-bullet">
<li><a name="toc-Options-62" href="#Options-62">27.3.1 Options</a></li>
<li><a name="toc-Examples-23" href="#Examples-23">27.3.2 Examples</a></li>
</ul></li>
<li><a name="toc-fbdev-1" href="#fbdev-1">27.4 fbdev</a>
<ul class="no-bullet">
<li><a name="toc-Options-63" href="#Options-63">27.4.1 Options</a></li>
<li><a name="toc-Examples-24" href="#Examples-24">27.4.2 Examples</a></li>
</ul></li>
<li><a name="toc-opengl" href="#opengl">27.5 opengl</a>
<ul class="no-bullet">
<li><a name="toc-Options-64" href="#Options-64">27.5.1 Options</a></li>
<li><a name="toc-Examples-25" href="#Examples-25">27.5.2 Examples</a></li>
</ul></li>
<li><a name="toc-oss-1" href="#oss-1">27.6 oss</a></li>
<li><a name="toc-pulse-1" href="#pulse-1">27.7 pulse</a>
<ul class="no-bullet">
<li><a name="toc-Options-65" href="#Options-65">27.7.1 Options</a></li>
<li><a name="toc-Examples-26" href="#Examples-26">27.7.2 Examples</a></li>
</ul></li>
<li><a name="toc-sdl" href="#sdl">27.8 sdl</a>
<ul class="no-bullet">
<li><a name="toc-Options-66" href="#Options-66">27.8.1 Options</a></li>
<li><a name="toc-Interactive-commands" href="#Interactive-commands">27.8.2 Interactive commands</a></li>
<li><a name="toc-Examples-27" href="#Examples-27">27.8.3 Examples</a></li>
</ul></li>
<li><a name="toc-sndio-1" href="#sndio-1">27.9 sndio</a></li>
<li><a name="toc-xv" href="#xv">27.10 xv</a>
<ul class="no-bullet">
<li><a name="toc-Options-67" href="#Options-67">27.10.1 Options</a></li>
<li><a name="toc-Examples-28" href="#Examples-28">27.10.2 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Resampler-Options" href="#Resampler-Options">28 Resampler Options</a></li>
<li><a name="toc-Scaler-Options" href="#Scaler-Options">29 Scaler Options</a></li>
<li><a name="toc-Filtering-Introduction" href="#Filtering-Introduction">30 Filtering Introduction</a></li>
<li><a name="toc-graph2dot" href="#graph2dot">31 graph2dot</a></li>
<li><a name="toc-Filtergraph-description" href="#Filtergraph-description">32 Filtergraph description</a>
<ul class="no-bullet">
<li><a name="toc-Filtergraph-syntax-1" href="#Filtergraph-syntax-1">32.1 Filtergraph syntax</a></li>
<li><a name="toc-Notes-on-filtergraph-escaping" href="#Notes-on-filtergraph-escaping">32.2 Notes on filtergraph escaping</a></li>
</ul></li>
<li><a name="toc-Timeline-editing" href="#Timeline-editing">33 Timeline editing</a></li>
<li><a name="toc-Audio-Filters" href="#Audio-Filters">34 Audio Filters</a>
<ul class="no-bullet">
<li><a name="toc-acrossfade" href="#acrossfade">34.1 acrossfade</a>
<ul class="no-bullet">
<li><a name="toc-Examples-29" href="#Examples-29">34.1.1 Examples</a></li>
</ul></li>
<li><a name="toc-adelay" href="#adelay">34.2 adelay</a>
<ul class="no-bullet">
<li><a name="toc-Examples-30" href="#Examples-30">34.2.1 Examples</a></li>
</ul></li>
<li><a name="toc-aecho" href="#aecho">34.3 aecho</a>
<ul class="no-bullet">
<li><a name="toc-Examples-31" href="#Examples-31">34.3.1 Examples</a></li>
</ul></li>
<li><a name="toc-aeval" href="#aeval">34.4 aeval</a>
<ul class="no-bullet">
<li><a name="toc-Examples-32" href="#Examples-32">34.4.1 Examples</a></li>
</ul></li>
<li><a name="toc-afade-1" href="#afade-1">34.5 afade</a>
<ul class="no-bullet">
<li><a name="toc-Examples-33" href="#Examples-33">34.5.1 Examples</a></li>
</ul></li>
<li><a name="toc-aformat-1" href="#aformat-1">34.6 aformat</a></li>
<li><a name="toc-allpass" href="#allpass">34.7 allpass</a></li>
<li><a name="toc-amerge-1" href="#amerge-1">34.8 amerge</a>
<ul class="no-bullet">
<li><a name="toc-Examples-34" href="#Examples-34">34.8.1 Examples</a></li>
</ul></li>
<li><a name="toc-amix" href="#amix">34.9 amix</a></li>
<li><a name="toc-anull" href="#anull">34.10 anull</a></li>
<li><a name="toc-apad" href="#apad">34.11 apad</a>
<ul class="no-bullet">
<li><a name="toc-Examples-35" href="#Examples-35">34.11.1 Examples</a></li>
</ul></li>
<li><a name="toc-aphaser" href="#aphaser">34.12 aphaser</a></li>
<li><a name="toc-aresample-1" href="#aresample-1">34.13 aresample</a>
<ul class="no-bullet">
<li><a name="toc-Examples-36" href="#Examples-36">34.13.1 Examples</a></li>
</ul></li>
<li><a name="toc-asetnsamples" href="#asetnsamples">34.14 asetnsamples</a></li>
<li><a name="toc-asetrate" href="#asetrate">34.15 asetrate</a></li>
<li><a name="toc-ashowinfo" href="#ashowinfo">34.16 ashowinfo</a></li>
<li><a name="toc-astats-1" href="#astats-1">34.17 astats</a></li>
<li><a name="toc-astreamsync" href="#astreamsync">34.18 astreamsync</a>
<ul class="no-bullet">
<li><a name="toc-Examples-37" href="#Examples-37">34.18.1 Examples</a></li>
</ul></li>
<li><a name="toc-asyncts" href="#asyncts">34.19 asyncts</a></li>
<li><a name="toc-atempo" href="#atempo">34.20 atempo</a>
<ul class="no-bullet">
<li><a name="toc-Examples-38" href="#Examples-38">34.20.1 Examples</a></li>
</ul></li>
<li><a name="toc-atrim" href="#atrim">34.21 atrim</a></li>
<li><a name="toc-bandpass" href="#bandpass">34.22 bandpass</a></li>
<li><a name="toc-bandreject" href="#bandreject">34.23 bandreject</a></li>
<li><a name="toc-bass" href="#bass">34.24 bass</a></li>
<li><a name="toc-biquad" href="#biquad">34.25 biquad</a></li>
<li><a name="toc-bs2b" href="#bs2b">34.26 bs2b</a></li>
<li><a name="toc-channelmap" href="#channelmap">34.27 channelmap</a></li>
<li><a name="toc-channelsplit" href="#channelsplit">34.28 channelsplit</a></li>
<li><a name="toc-chorus" href="#chorus">34.29 chorus</a>
<ul class="no-bullet">
<li><a name="toc-Examples-39" href="#Examples-39">34.29.1 Examples</a></li>
</ul></li>
<li><a name="toc-compand" href="#compand">34.30 compand</a>
<ul class="no-bullet">
<li><a name="toc-Examples-40" href="#Examples-40">34.30.1 Examples</a></li>
</ul></li>
<li><a name="toc-dcshift" href="#dcshift">34.31 dcshift</a></li>
<li><a name="toc-dynaudnorm" href="#dynaudnorm">34.32 dynaudnorm</a></li>
<li><a name="toc-earwax" href="#earwax">34.33 earwax</a></li>
<li><a name="toc-equalizer" href="#equalizer">34.34 equalizer</a>
<ul class="no-bullet">
<li><a name="toc-Examples-41" href="#Examples-41">34.34.1 Examples</a></li>
</ul></li>
<li><a name="toc-flanger" href="#flanger">34.35 flanger</a></li>
<li><a name="toc-highpass" href="#highpass">34.36 highpass</a></li>
<li><a name="toc-join" href="#join">34.37 join</a></li>
<li><a name="toc-ladspa" href="#ladspa">34.38 ladspa</a>
<ul class="no-bullet">
<li><a name="toc-Examples-42" href="#Examples-42">34.38.1 Examples</a></li>
<li><a name="toc-Commands" href="#Commands">34.38.2 Commands</a></li>
</ul></li>
<li><a name="toc-lowpass" href="#lowpass">34.39 lowpass</a></li>
<li><a name="toc-pan-1" href="#pan-1">34.40 pan</a>
<ul class="no-bullet">
<li><a name="toc-Mixing-examples" href="#Mixing-examples">34.40.1 Mixing examples</a></li>
<li><a name="toc-Remapping-examples" href="#Remapping-examples">34.40.2 Remapping examples</a></li>
</ul></li>
<li><a name="toc-replaygain" href="#replaygain">34.41 replaygain</a></li>
<li><a name="toc-resample" href="#resample">34.42 resample</a></li>
<li><a name="toc-sidechaincompress" href="#sidechaincompress">34.43 sidechaincompress</a>
<ul class="no-bullet">
<li><a name="toc-Examples-43" href="#Examples-43">34.43.1 Examples</a></li>
</ul></li>
<li><a name="toc-silencedetect" href="#silencedetect">34.44 silencedetect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-44" href="#Examples-44">34.44.1 Examples</a></li>
</ul></li>
<li><a name="toc-silenceremove" href="#silenceremove">34.45 silenceremove</a>
<ul class="no-bullet">
<li><a name="toc-Examples-45" href="#Examples-45">34.45.1 Examples</a></li>
</ul></li>
<li><a name="toc-treble" href="#treble">34.46 treble</a></li>
<li><a name="toc-volume" href="#volume">34.47 volume</a>
<ul class="no-bullet">
<li><a name="toc-Commands-1" href="#Commands-1">34.47.1 Commands</a></li>
<li><a name="toc-Examples-46" href="#Examples-46">34.47.2 Examples</a></li>
</ul></li>
<li><a name="toc-volumedetect" href="#volumedetect">34.48 volumedetect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-47" href="#Examples-47">34.48.1 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Audio-Sources" href="#Audio-Sources">35 Audio Sources</a>
<ul class="no-bullet">
<li><a name="toc-abuffer" href="#abuffer">35.1 abuffer</a>
<ul class="no-bullet">
<li><a name="toc-Examples-48" href="#Examples-48">35.1.1 Examples</a></li>
</ul></li>
<li><a name="toc-aevalsrc" href="#aevalsrc">35.2 aevalsrc</a>
<ul class="no-bullet">
<li><a name="toc-Examples-49" href="#Examples-49">35.2.1 Examples</a></li>
</ul></li>
<li><a name="toc-anullsrc" href="#anullsrc">35.3 anullsrc</a>
<ul class="no-bullet">
<li><a name="toc-Examples-50" href="#Examples-50">35.3.1 Examples</a></li>
</ul></li>
<li><a name="toc-flite" href="#flite">35.4 flite</a>
<ul class="no-bullet">
<li><a name="toc-Examples-51" href="#Examples-51">35.4.1 Examples</a></li>
</ul></li>
<li><a name="toc-sine" href="#sine">35.5 sine</a>
<ul class="no-bullet">
<li><a name="toc-Examples-52" href="#Examples-52">35.5.1 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Audio-Sinks" href="#Audio-Sinks">36 Audio Sinks</a>
<ul class="no-bullet">
<li><a name="toc-abuffersink" href="#abuffersink">36.1 abuffersink</a></li>
<li><a name="toc-anullsink" href="#anullsink">36.2 anullsink</a></li>
</ul></li>
<li><a name="toc-Video-Filters" href="#Video-Filters">37 Video Filters</a>
<ul class="no-bullet">
<li><a name="toc-alphaextract" href="#alphaextract">37.1 alphaextract</a></li>
<li><a name="toc-alphamerge" href="#alphamerge">37.2 alphamerge</a></li>
<li><a name="toc-ass" href="#ass">37.3 ass</a></li>
<li><a name="toc-atadenoise" href="#atadenoise">37.4 atadenoise</a></li>
<li><a name="toc-bbox" href="#bbox">37.5 bbox</a></li>
<li><a name="toc-blackdetect" href="#blackdetect">37.6 blackdetect</a></li>
<li><a name="toc-blackframe" href="#blackframe">37.7 blackframe</a></li>
<li><a name="toc-blend_002c-tblend" href="#blend_002c-tblend">37.8 blend, tblend</a>
<ul class="no-bullet">
<li><a name="toc-Examples-53" href="#Examples-53">37.8.1 Examples</a></li>
</ul></li>
<li><a name="toc-boxblur" href="#boxblur">37.9 boxblur</a>
<ul class="no-bullet">
<li><a name="toc-Examples-54" href="#Examples-54">37.9.1 Examples</a></li>
</ul></li>
<li><a name="toc-codecview" href="#codecview">37.10 codecview</a>
<ul class="no-bullet">
<li><a name="toc-Examples-55" href="#Examples-55">37.10.1 Examples</a></li>
</ul></li>
<li><a name="toc-colorbalance" href="#colorbalance">37.11 colorbalance</a>
<ul class="no-bullet">
<li><a name="toc-Examples-56" href="#Examples-56">37.11.1 Examples</a></li>
</ul></li>
<li><a name="toc-colorkey" href="#colorkey">37.12 colorkey</a>
<ul class="no-bullet">
<li><a name="toc-Examples-57" href="#Examples-57">37.12.1 Examples</a></li>
</ul></li>
<li><a name="toc-colorlevels" href="#colorlevels">37.13 colorlevels</a>
<ul class="no-bullet">
<li><a name="toc-Examples-58" href="#Examples-58">37.13.1 Examples</a></li>
</ul></li>
<li><a name="toc-colorchannelmixer" href="#colorchannelmixer">37.14 colorchannelmixer</a>
<ul class="no-bullet">
<li><a name="toc-Examples-59" href="#Examples-59">37.14.1 Examples</a></li>
</ul></li>
<li><a name="toc-colormatrix" href="#colormatrix">37.15 colormatrix</a></li>
<li><a name="toc-copy" href="#copy">37.16 copy</a></li>
<li><a name="toc-crop" href="#crop">37.17 crop</a>
<ul class="no-bullet">
<li><a name="toc-Examples-60" href="#Examples-60">37.17.1 Examples</a></li>
<li><a name="toc-Commands-2" href="#Commands-2">37.17.2 Commands</a></li>
</ul></li>
<li><a name="toc-cropdetect" href="#cropdetect">37.18 cropdetect</a></li>
<li><a name="toc-curves-1" href="#curves-1">37.19 curves</a>
<ul class="no-bullet">
<li><a name="toc-Examples-61" href="#Examples-61">37.19.1 Examples</a></li>
</ul></li>
<li><a name="toc-dctdnoiz" href="#dctdnoiz">37.20 dctdnoiz</a>
<ul class="no-bullet">
<li><a name="toc-Examples-62" href="#Examples-62">37.20.1 Examples</a></li>
</ul></li>
<li><a name="toc-deband" href="#deband">37.21 deband</a></li>
<li><a name="toc-decimate-1" href="#decimate-1">37.22 decimate</a></li>
<li><a name="toc-deflate" href="#deflate">37.23 deflate</a></li>
<li><a name="toc-dejudder" href="#dejudder">37.24 dejudder</a></li>
<li><a name="toc-delogo" href="#delogo">37.25 delogo</a>
<ul class="no-bullet">
<li><a name="toc-Examples-63" href="#Examples-63">37.25.1 Examples</a></li>
</ul></li>
<li><a name="toc-deshake" href="#deshake">37.26 deshake</a></li>
<li><a name="toc-detelecine" href="#detelecine">37.27 detelecine</a></li>
<li><a name="toc-dilation" href="#dilation">37.28 dilation</a></li>
<li><a name="toc-drawbox" href="#drawbox">37.29 drawbox</a>
<ul class="no-bullet">
<li><a name="toc-Examples-64" href="#Examples-64">37.29.1 Examples</a></li>
</ul></li>
<li><a name="toc-drawgraph_002c-adrawgraph" href="#drawgraph_002c-adrawgraph">37.30 drawgraph, adrawgraph</a></li>
<li><a name="toc-drawgrid" href="#drawgrid">37.31 drawgrid</a>
<ul class="no-bullet">
<li><a name="toc-Examples-65" href="#Examples-65">37.31.1 Examples</a></li>
</ul></li>
<li><a name="toc-drawtext-1" href="#drawtext-1">37.32 drawtext</a>
<ul class="no-bullet">
<li><a name="toc-Syntax-2" href="#Syntax-2">37.32.1 Syntax</a></li>
<li><a name="toc-Text-expansion" href="#Text-expansion">37.32.2 Text expansion</a></li>
<li><a name="toc-Examples-66" href="#Examples-66">37.32.3 Examples</a></li>
</ul></li>
<li><a name="toc-edgedetect" href="#edgedetect">37.33 edgedetect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-67" href="#Examples-67">37.33.1 Examples</a></li>
</ul></li>
<li><a name="toc-eq" href="#eq">37.34 eq</a>
<ul class="no-bullet">
<li><a name="toc-Commands-3" href="#Commands-3">37.34.1 Commands</a></li>
</ul></li>
<li><a name="toc-erosion" href="#erosion">37.35 erosion</a></li>
<li><a name="toc-extractplanes" href="#extractplanes">37.36 extractplanes</a>
<ul class="no-bullet">
<li><a name="toc-Examples-68" href="#Examples-68">37.36.1 Examples</a></li>
</ul></li>
<li><a name="toc-elbg" href="#elbg">37.37 elbg</a></li>
<li><a name="toc-fade" href="#fade">37.38 fade</a>
<ul class="no-bullet">
<li><a name="toc-Examples-69" href="#Examples-69">37.38.1 Examples</a></li>
</ul></li>
<li><a name="toc-fftfilt" href="#fftfilt">37.39 fftfilt</a>
<ul class="no-bullet">
<li><a name="toc-Examples-70" href="#Examples-70">37.39.1 Examples</a></li>
</ul></li>
<li><a name="toc-field" href="#field">37.40 field</a></li>
<li><a name="toc-fieldmatch" href="#fieldmatch">37.41 fieldmatch</a>
<ul class="no-bullet">
<li><a name="toc-p_002fc_002fn_002fu_002fb-meaning-1" href="#p_002fc_002fn_002fu_002fb-meaning-1">37.41.1 p/c/n/u/b meaning</a>
<ul class="no-bullet">
<li><a name="toc-p_002fc_002fn" href="#p_002fc_002fn">37.41.1.1 p/c/n</a></li>
<li><a name="toc-u_002fb" href="#u_002fb">37.41.1.2 u/b</a></li>
</ul></li>
<li><a name="toc-Examples-71" href="#Examples-71">37.41.2 Examples</a></li>
</ul></li>
<li><a name="toc-fieldorder" href="#fieldorder">37.42 fieldorder</a></li>
<li><a name="toc-fifo" href="#fifo">37.43 fifo</a></li>
<li><a name="toc-find_005frect" href="#find_005frect">37.44 find_rect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-72" href="#Examples-72">37.44.1 Examples</a></li>
</ul></li>
<li><a name="toc-cover_005frect" href="#cover_005frect">37.45 cover_rect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-73" href="#Examples-73">37.45.1 Examples</a></li>
</ul></li>
<li><a name="toc-format-1" href="#format-1">37.46 format</a>
<ul class="no-bullet">
<li><a name="toc-Examples-74" href="#Examples-74">37.46.1 Examples</a></li>
</ul></li>
<li><a name="toc-fps-1" href="#fps-1">37.47 fps</a>
<ul class="no-bullet">
<li><a name="toc-Examples-75" href="#Examples-75">37.47.1 Examples</a></li>
</ul></li>
<li><a name="toc-framepack" href="#framepack">37.48 framepack</a></li>
<li><a name="toc-framerate" href="#framerate">37.49 framerate</a></li>
<li><a name="toc-framestep" href="#framestep">37.50 framestep</a></li>
<li><a name="toc-frei0r-1" href="#frei0r-1">37.51 frei0r</a>
<ul class="no-bullet">
<li><a name="toc-Examples-76" href="#Examples-76">37.51.1 Examples</a></li>
</ul></li>
<li><a name="toc-fspp" href="#fspp">37.52 fspp</a></li>
<li><a name="toc-geq" href="#geq">37.53 geq</a>
<ul class="no-bullet">
<li><a name="toc-Examples-77" href="#Examples-77">37.53.1 Examples</a></li>
</ul></li>
<li><a name="toc-gradfun" href="#gradfun">37.54 gradfun</a>
<ul class="no-bullet">
<li><a name="toc-Examples-78" href="#Examples-78">37.54.1 Examples</a></li>
</ul></li>
<li><a name="toc-haldclut-1" href="#haldclut-1">37.55 haldclut</a>
<ul class="no-bullet">
<li><a name="toc-Workflow-examples" href="#Workflow-examples">37.55.1 Workflow examples</a>
<ul class="no-bullet">
<li><a name="toc-Hald-CLUT-video-stream" href="#Hald-CLUT-video-stream">37.55.1.1 Hald CLUT video stream</a></li>
<li><a name="toc-Hald-CLUT-with-preview" href="#Hald-CLUT-with-preview">37.55.1.2 Hald CLUT with preview</a></li>
</ul></li>
</ul></li>
<li><a name="toc-hflip" href="#hflip">37.56 hflip</a></li>
<li><a name="toc-histeq" href="#histeq">37.57 histeq</a></li>
<li><a name="toc-histogram" href="#histogram">37.58 histogram</a>
<ul class="no-bullet">
<li><a name="toc-Examples-79" href="#Examples-79">37.58.1 Examples</a></li>
</ul></li>
<li><a name="toc-hqdn3d-1" href="#hqdn3d-1">37.59 hqdn3d</a></li>
<li><a name="toc-hqx" href="#hqx">37.60 hqx</a></li>
<li><a name="toc-hstack" href="#hstack">37.61 hstack</a></li>
<li><a name="toc-hue" href="#hue">37.62 hue</a>
<ul class="no-bullet">
<li><a name="toc-Examples-80" href="#Examples-80">37.62.1 Examples</a></li>
<li><a name="toc-Commands-4" href="#Commands-4">37.62.2 Commands</a></li>
</ul></li>
<li><a name="toc-idet" href="#idet">37.63 idet</a></li>
<li><a name="toc-il" href="#il">37.64 il</a></li>
<li><a name="toc-inflate" href="#inflate">37.65 inflate</a></li>
<li><a name="toc-interlace" href="#interlace">37.66 interlace</a></li>
<li><a name="toc-kerndeint" href="#kerndeint">37.67 kerndeint</a>
<ul class="no-bullet">
<li><a name="toc-Examples-81" href="#Examples-81">37.67.1 Examples</a></li>
</ul></li>
<li><a name="toc-lenscorrection" href="#lenscorrection">37.68 lenscorrection</a>
<ul class="no-bullet">
<li><a name="toc-Options-68" href="#Options-68">37.68.1 Options</a></li>
</ul></li>
<li><a name="toc-lut3d-1" href="#lut3d-1">37.69 lut3d</a></li>
<li><a name="toc-lut_002c-lutrgb_002c-lutyuv" href="#lut_002c-lutrgb_002c-lutyuv">37.70 lut, lutrgb, lutyuv</a>
<ul class="no-bullet">
<li><a name="toc-Examples-82" href="#Examples-82">37.70.1 Examples</a></li>
</ul></li>
<li><a name="toc-mergeplanes" href="#mergeplanes">37.71 mergeplanes</a>
<ul class="no-bullet">
<li><a name="toc-Examples-83" href="#Examples-83">37.71.1 Examples</a></li>
</ul></li>
<li><a name="toc-mcdeint" href="#mcdeint">37.72 mcdeint</a></li>
<li><a name="toc-mpdecimate" href="#mpdecimate">37.73 mpdecimate</a></li>
<li><a name="toc-negate" href="#negate">37.74 negate</a></li>
<li><a name="toc-noformat" href="#noformat">37.75 noformat</a>
<ul class="no-bullet">
<li><a name="toc-Examples-84" href="#Examples-84">37.75.1 Examples</a></li>
</ul></li>
<li><a name="toc-noise-1" href="#noise-1">37.76 noise</a>
<ul class="no-bullet">
<li><a name="toc-Examples-85" href="#Examples-85">37.76.1 Examples</a></li>
</ul></li>
<li><a name="toc-null-1" href="#null-1">37.77 null</a></li>
<li><a name="toc-ocv" href="#ocv">37.78 ocv</a>
<ul class="no-bullet">
<li><a name="toc-dilate-1" href="#dilate-1">37.78.1 dilate</a></li>
<li><a name="toc-erode" href="#erode">37.78.2 erode</a></li>
<li><a name="toc-smooth" href="#smooth">37.78.3 smooth</a></li>
</ul></li>
<li><a name="toc-overlay-1" href="#overlay-1">37.79 overlay</a>
<ul class="no-bullet">
<li><a name="toc-Commands-5" href="#Commands-5">37.79.1 Commands</a></li>
<li><a name="toc-Examples-86" href="#Examples-86">37.79.2 Examples</a></li>
</ul></li>
<li><a name="toc-owdenoise" href="#owdenoise">37.80 owdenoise</a></li>
<li><a name="toc-pad-1" href="#pad-1">37.81 pad</a>
<ul class="no-bullet">
<li><a name="toc-Examples-87" href="#Examples-87">37.81.1 Examples</a></li>
</ul></li>
<li><a name="toc-palettegen-1" href="#palettegen-1">37.82 palettegen</a>
<ul class="no-bullet">
<li><a name="toc-Examples-88" href="#Examples-88">37.82.1 Examples</a></li>
</ul></li>
<li><a name="toc-paletteuse" href="#paletteuse">37.83 paletteuse</a>
<ul class="no-bullet">
<li><a name="toc-Examples-89" href="#Examples-89">37.83.1 Examples</a></li>
</ul></li>
<li><a name="toc-perspective" href="#perspective">37.84 perspective</a></li>
<li><a name="toc-phase" href="#phase">37.85 phase</a></li>
<li><a name="toc-pixdesctest" href="#pixdesctest">37.86 pixdesctest</a></li>
<li><a name="toc-pp" href="#pp">37.87 pp</a>
<ul class="no-bullet">
<li><a name="toc-Examples-90" href="#Examples-90">37.87.1 Examples</a></li>
</ul></li>
<li><a name="toc-pp7" href="#pp7">37.88 pp7</a></li>
<li><a name="toc-psnr" href="#psnr">37.89 psnr</a></li>
<li><a name="toc-pullup-1" href="#pullup-1">37.90 pullup</a></li>
<li><a name="toc-qp" href="#qp">37.91 qp</a>
<ul class="no-bullet">
<li><a name="toc-Examples-91" href="#Examples-91">37.91.1 Examples</a></li>
</ul></li>
<li><a name="toc-random" href="#random">37.92 random</a></li>
<li><a name="toc-removegrain" href="#removegrain">37.93 removegrain</a></li>
<li><a name="toc-removelogo" href="#removelogo">37.94 removelogo</a></li>
<li><a name="toc-repeatfields" href="#repeatfields">37.95 repeatfields</a></li>
<li><a name="toc-reverse_002c-areverse" href="#reverse_002c-areverse">37.96 reverse, areverse</a>
<ul class="no-bullet">
<li><a name="toc-Examples-92" href="#Examples-92">37.96.1 Examples</a></li>
</ul></li>
<li><a name="toc-rotate" href="#rotate">37.97 rotate</a>
<ul class="no-bullet">
<li><a name="toc-Examples-93" href="#Examples-93">37.97.1 Examples</a></li>
<li><a name="toc-Commands-6" href="#Commands-6">37.97.2 Commands</a></li>
</ul></li>
<li><a name="toc-sab" href="#sab">37.98 sab</a></li>
<li><a name="toc-scale-1" href="#scale-1">37.99 scale</a>
<ul class="no-bullet">
<li><a name="toc-Options-69" href="#Options-69">37.99.1 Options</a></li>
<li><a name="toc-Examples-94" href="#Examples-94">37.99.2 Examples</a></li>
<li><a name="toc-Commands-7" href="#Commands-7">37.99.3 Commands</a></li>
</ul></li>
<li><a name="toc-scale2ref" href="#scale2ref">37.100 scale2ref</a>
<ul class="no-bullet">
<li><a name="toc-Examples-95" href="#Examples-95">37.100.1 Examples</a></li>
</ul></li>
<li><a name="toc-separatefields" href="#separatefields">37.101 separatefields</a></li>
<li><a name="toc-setdar_002c-setsar" href="#setdar_002c-setsar">37.102 setdar, setsar</a>
<ul class="no-bullet">
<li><a name="toc-Examples-96" href="#Examples-96">37.102.1 Examples</a></li>
</ul></li>
<li><a name="toc-setfield-1" href="#setfield-1">37.103 setfield</a></li>
<li><a name="toc-showinfo" href="#showinfo">37.104 showinfo</a></li>
<li><a name="toc-showpalette" href="#showpalette">37.105 showpalette</a></li>
<li><a name="toc-shuffleplanes" href="#shuffleplanes">37.106 shuffleplanes</a></li>
<li><a name="toc-signalstats-1" href="#signalstats-1">37.107 signalstats</a>
<ul class="no-bullet">
<li><a name="toc-Examples-97" href="#Examples-97">37.107.1 Examples</a></li>
</ul></li>
<li><a name="toc-smartblur-1" href="#smartblur-1">37.108 smartblur</a></li>
<li><a name="toc-ssim" href="#ssim">37.109 ssim</a></li>
<li><a name="toc-stereo3d" href="#stereo3d">37.110 stereo3d</a>
<ul class="no-bullet">
<li><a name="toc-Examples-98" href="#Examples-98">37.110.1 Examples</a></li>
</ul></li>
<li><a name="toc-spp-1" href="#spp-1">37.111 spp</a></li>
<li><a name="toc-subtitles-1" href="#subtitles-1">37.112 subtitles</a></li>
<li><a name="toc-super2xsai" href="#super2xsai">37.113 super2xsai</a></li>
<li><a name="toc-swapuv" href="#swapuv">37.114 swapuv</a></li>
<li><a name="toc-telecine" href="#telecine">37.115 telecine</a></li>
<li><a name="toc-thumbnail" href="#thumbnail">37.116 thumbnail</a>
<ul class="no-bullet">
<li><a name="toc-Examples-99" href="#Examples-99">37.116.1 Examples</a></li>
</ul></li>
<li><a name="toc-tile" href="#tile">37.117 tile</a>
<ul class="no-bullet">
<li><a name="toc-Examples-100" href="#Examples-100">37.117.1 Examples</a></li>
</ul></li>
<li><a name="toc-tinterlace" href="#tinterlace">37.118 tinterlace</a></li>
<li><a name="toc-transpose" href="#transpose">37.119 transpose</a></li>
<li><a name="toc-trim" href="#trim">37.120 trim</a></li>
<li><a name="toc-unsharp-1" href="#unsharp-1">37.121 unsharp</a>
<ul class="no-bullet">
<li><a name="toc-Examples-101" href="#Examples-101">37.121.1 Examples</a></li>
</ul></li>
<li><a name="toc-uspp" href="#uspp">37.122 uspp</a></li>
<li><a name="toc-vectorscope" href="#vectorscope">37.123 vectorscope</a></li>
<li><a name="toc-vidstabdetect-1" href="#vidstabdetect-1">37.124 vidstabdetect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-102" href="#Examples-102">37.124.1 Examples</a></li>
</ul></li>
<li><a name="toc-vidstabtransform-1" href="#vidstabtransform-1">37.125 vidstabtransform</a>
<ul class="no-bullet">
<li><a name="toc-Options-70" href="#Options-70">37.125.1 Options</a></li>
<li><a name="toc-Examples-103" href="#Examples-103">37.125.2 Examples</a></li>
</ul></li>
<li><a name="toc-vflip" href="#vflip">37.126 vflip</a></li>
<li><a name="toc-vignette-1" href="#vignette-1">37.127 vignette</a>
<ul class="no-bullet">
<li><a name="toc-Expressions" href="#Expressions">37.127.1 Expressions</a></li>
<li><a name="toc-Examples-104" href="#Examples-104">37.127.2 Examples</a></li>
</ul></li>
<li><a name="toc-vstack" href="#vstack">37.128 vstack</a></li>
<li><a name="toc-w3fdif" href="#w3fdif">37.129 w3fdif</a></li>
<li><a name="toc-waveform" href="#waveform">37.130 waveform</a></li>
<li><a name="toc-xbr" href="#xbr">37.131 xbr</a></li>
<li><a name="toc-yadif-1" href="#yadif-1">37.132 yadif</a></li>
<li><a name="toc-zoompan" href="#zoompan">37.133 zoompan</a>
<ul class="no-bullet">
<li><a name="toc-Examples-105" href="#Examples-105">37.133.1 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Video-Sources" href="#Video-Sources">38 Video Sources</a>
<ul class="no-bullet">
<li><a name="toc-buffer" href="#buffer">38.1 buffer</a></li>
<li><a name="toc-cellauto" href="#cellauto">38.2 cellauto</a>
<ul class="no-bullet">
<li><a name="toc-Examples-106" href="#Examples-106">38.2.1 Examples</a></li>
</ul></li>
<li><a name="toc-mandelbrot" href="#mandelbrot">38.3 mandelbrot</a></li>
<li><a name="toc-mptestsrc" href="#mptestsrc">38.4 mptestsrc</a></li>
<li><a name="toc-frei0r_005fsrc" href="#frei0r_005fsrc">38.5 frei0r_src</a></li>
<li><a name="toc-life" href="#life">38.6 life</a>
<ul class="no-bullet">
<li><a name="toc-Examples-107" href="#Examples-107">38.6.1 Examples</a></li>
</ul></li>
<li><a name="toc-allrgb_002c-allyuv_002c-color_002c-haldclutsrc_002c-nullsrc_002c-rgbtestsrc_002c-smptebars_002c-smptehdbars_002c-testsrc" href="#allrgb_002c-allyuv_002c-color_002c-haldclutsrc_002c-nullsrc_002c-rgbtestsrc_002c-smptebars_002c-smptehdbars_002c-testsrc">38.7 allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc</a>
<ul class="no-bullet">
<li><a name="toc-Commands-8" href="#Commands-8">38.7.1 Commands</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Video-Sinks" href="#Video-Sinks">39 Video Sinks</a>
<ul class="no-bullet">
<li><a name="toc-buffersink" href="#buffersink">39.1 buffersink</a></li>
<li><a name="toc-nullsink" href="#nullsink">39.2 nullsink</a></li>
</ul></li>
<li><a name="toc-Multimedia-Filters" href="#Multimedia-Filters">40 Multimedia Filters</a>
<ul class="no-bullet">
<li><a name="toc-aphasemeter" href="#aphasemeter">40.1 aphasemeter</a></li>
<li><a name="toc-avectorscope" href="#avectorscope">40.2 avectorscope</a>
<ul class="no-bullet">
<li><a name="toc-Examples-108" href="#Examples-108">40.2.1 Examples</a></li>
</ul></li>
<li><a name="toc-concat-3" href="#concat-3">40.3 concat</a>
<ul class="no-bullet">
<li><a name="toc-Examples-109" href="#Examples-109">40.3.1 Examples</a></li>
</ul></li>
<li><a name="toc-ebur128-1" href="#ebur128-1">40.4 ebur128</a>
<ul class="no-bullet">
<li><a name="toc-Examples-110" href="#Examples-110">40.4.1 Examples</a></li>
</ul></li>
<li><a name="toc-interleave_002c-ainterleave" href="#interleave_002c-ainterleave">40.5 interleave, ainterleave</a>
<ul class="no-bullet">
<li><a name="toc-Examples-111" href="#Examples-111">40.5.1 Examples</a></li>
</ul></li>
<li><a name="toc-perms_002c-aperms" href="#perms_002c-aperms">40.6 perms, aperms</a></li>
<li><a name="toc-select_002c-aselect" href="#select_002c-aselect">40.7 select, aselect</a>
<ul class="no-bullet">
<li><a name="toc-Examples-112" href="#Examples-112">40.7.1 Examples</a></li>
</ul></li>
<li><a name="toc-sendcmd_002c-asendcmd" href="#sendcmd_002c-asendcmd">40.8 sendcmd, asendcmd</a>
<ul class="no-bullet">
<li><a name="toc-Commands-syntax" href="#Commands-syntax">40.8.1 Commands syntax</a></li>
<li><a name="toc-Examples-113" href="#Examples-113">40.8.2 Examples</a></li>
</ul></li>
<li><a name="toc-setpts_002c-asetpts" href="#setpts_002c-asetpts">40.9 setpts, asetpts</a>
<ul class="no-bullet">
<li><a name="toc-Examples-114" href="#Examples-114">40.9.1 Examples</a></li>
</ul></li>
<li><a name="toc-settb_002c-asettb" href="#settb_002c-asettb">40.10 settb, asettb</a>
<ul class="no-bullet">
<li><a name="toc-Examples-115" href="#Examples-115">40.10.1 Examples</a></li>
</ul></li>
<li><a name="toc-showcqt" href="#showcqt">40.11 showcqt</a>
<ul class="no-bullet">
<li><a name="toc-Examples-116" href="#Examples-116">40.11.1 Examples</a></li>
</ul></li>
<li><a name="toc-showfreqs" href="#showfreqs">40.12 showfreqs</a></li>
<li><a name="toc-showspectrum" href="#showspectrum">40.13 showspectrum</a>
<ul class="no-bullet">
<li><a name="toc-Examples-117" href="#Examples-117">40.13.1 Examples</a></li>
</ul></li>
<li><a name="toc-showvolume" href="#showvolume">40.14 showvolume</a></li>
<li><a name="toc-showwaves" href="#showwaves">40.15 showwaves</a>
<ul class="no-bullet">
<li><a name="toc-Examples-118" href="#Examples-118">40.15.1 Examples</a></li>
</ul></li>
<li><a name="toc-showwavespic" href="#showwavespic">40.16 showwavespic</a>
<ul class="no-bullet">
<li><a name="toc-Examples-119" href="#Examples-119">40.16.1 Examples</a></li>
</ul></li>
<li><a name="toc-split_002c-asplit" href="#split_002c-asplit">40.17 split, asplit</a>
<ul class="no-bullet">
<li><a name="toc-Examples-120" href="#Examples-120">40.17.1 Examples</a></li>
</ul></li>
<li><a name="toc-zmq_002c-azmq" href="#zmq_002c-azmq">40.18 zmq, azmq</a>
<ul class="no-bullet">
<li><a name="toc-Examples-121" href="#Examples-121">40.18.1 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Multimedia-Sources" href="#Multimedia-Sources">41 Multimedia Sources</a>
<ul class="no-bullet">
<li><a name="toc-amovie" href="#amovie">41.1 amovie</a></li>
<li><a name="toc-movie-1" href="#movie-1">41.2 movie</a>
<ul class="no-bullet">
<li><a name="toc-Examples-122" href="#Examples-122">41.2.1 Examples</a></li>
</ul></li>
</ul></li>
<li><a name="toc-See-Also" href="#See-Also">42 See Also</a></li>
<li><a name="toc-Authors" href="#Authors">43 Authors</a></li>
</ul>
</div>
<a name="Synopsis"></a>
<h2 class="chapter">1 Synopsis<span class="pull-right"><a class="anchor hidden-xs" href="#Synopsis" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Synopsis" aria-hidden="true">TOC</a></span></h2>
<p>ffserver [<var>options</var>]
</p>
<a name="Description"></a>
<h2 class="chapter">2 Description<span class="pull-right"><a class="anchor hidden-xs" href="#Description" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Description" aria-hidden="true">TOC</a></span></h2>
<p><code>ffserver</code> is a streaming server for both audio and video.
It supports several live feeds, streaming from files and time shifting
on live feeds. You can seek to positions in the past on each live
feed, provided you specify a big enough feed storage.
</p>
<p><code>ffserver</code> is configured through a configuration file, which
is read at startup. If not explicitly specified, it will read from
<samp>/etc/ffserver.conf</samp>.
</p>
<p><code>ffserver</code> receives prerecorded files or FFM streams from some
<code>ffmpeg</code> instance as input, then streams them over
RTP/RTSP/HTTP.
</p>
<p>An <code>ffserver</code> instance will listen on some port as specified
in the configuration file. You can launch one or more instances of
<code>ffmpeg</code> and send one or more FFM streams to the port where
ffserver is expecting to receive them. Alternately, you can make
<code>ffserver</code> launch such <code>ffmpeg</code> instances at startup.
</p>
<p>Input streams are called feeds, and each one is specified by a
<code><Feed></code> section in the configuration file.
</p>
<p>For each feed you can have different output streams in various
formats, each one specified by a <code><Stream></code> section in the
configuration file.
</p>
<a name="Detailed-description"></a>
<h2 class="chapter">3 Detailed description<span class="pull-right"><a class="anchor hidden-xs" href="#Detailed-description" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Detailed-description" aria-hidden="true">TOC</a></span></h2>
<p><code>ffserver</code> works by forwarding streams encoded by
<code>ffmpeg</code>, or pre-recorded streams which are read from disk.
</p>
<p>Precisely, <code>ffserver</code> acts as an HTTP server, accepting POST
requests from <code>ffmpeg</code> to acquire the stream to publish, and
serving RTSP clients or HTTP clients GET requests with the stream
media content.
</p>
<p>A feed is an <a href="#FFM">FFM</a> stream created by <code>ffmpeg</code>, and sent to
a port where <code>ffserver</code> is listening.
</p>
<p>Each feed is identified by a unique name, corresponding to the name
of the resource published on <code>ffserver</code>, and is configured by
a dedicated <code>Feed</code> section in the configuration file.
</p>
<p>The feed publish URL is given by:
</p><div class="example">
<pre class="example">http://<var>ffserver_ip_address</var>:<var>http_port</var>/<var>feed_name</var>
</pre></div>
<p>where <var>ffserver_ip_address</var> is the IP address of the machine where
<code>ffserver</code> is installed, <var>http_port</var> is the port number of
the HTTP server (configured through the <samp>HTTPPort</samp> option), and
<var>feed_name</var> is the name of the corresponding feed defined in the
configuration file.
</p>
<p>Each feed is associated to a file which is stored on disk. This stored
file is used to send pre-recorded data to a player as fast as
possible when new content is added in real-time to the stream.
</p>
<p>A "live-stream" or "stream" is a resource published by
<code>ffserver</code>, and made accessible through the HTTP protocol to
clients.
</p>
<p>A stream can be connected to a feed, or to a file. In the first case,
the published stream is forwarded from the corresponding feed
generated by a running instance of <code>ffmpeg</code>, in the second
case the stream is read from a pre-recorded file.
</p>
<p>Each stream is identified by a unique name, corresponding to the name
of the resource served by <code>ffserver</code>, and is configured by
a dedicated <code>Stream</code> section in the configuration file.
</p>
<p>The stream access HTTP URL is given by:
</p><div class="example">
<pre class="example">http://<var>ffserver_ip_address</var>:<var>http_port</var>/<var>stream_name</var>[<var>options</var>]
</pre></div>
<p>The stream access RTSP URL is given by:
</p><div class="example">
<pre class="example">http://<var>ffserver_ip_address</var>:<var>rtsp_port</var>/<var>stream_name</var>[<var>options</var>]
</pre></div>
<p><var>stream_name</var> is the name of the corresponding stream defined in
the configuration file. <var>options</var> is a list of options specified
after the URL which affects how the stream is served by
<code>ffserver</code>. <var>http_port</var> and <var>rtsp_port</var> are the HTTP
and RTSP ports configured with the options <var>HTTPPort</var> and
<var>RTSPPort</var> respectively.
</p>
<p>In case the stream is associated to a feed, the encoding parameters
must be configured in the stream configuration. They are sent to
<code>ffmpeg</code> when setting up the encoding. This allows
<code>ffserver</code> to define the encoding parameters used by
the <code>ffmpeg</code> encoders.
</p>
<p>The <code>ffmpeg</code> <samp>override_ffserver</samp> commandline option
allows one to override the encoding parameters set by the server.
</p>
<p>Multiple streams can be connected to the same feed.
</p>
<p>For example, you can have a situation described by the following
graph:
</p>
<pre class="verbatim"> _________ __________
| | | |
ffmpeg 1 -----| feed 1 |-----| stream 1 |
\ |_________|\ |__________|
\ \
\ \ __________
\ \ | |
\ \| stream 2 |
\ |__________|
\
\ _________ __________
\ | | | |
\| feed 2 |-----| stream 3 |
|_________| |__________|
_________ __________
| | | |
ffmpeg 2 -----| feed 3 |-----| stream 4 |
|_________| |__________|
_________ __________
| | | |
| file 1 |-----| stream 5 |
|_________| |__________|
</pre>
<a name="FFM"></a><a name="FFM_002c-FFM2-formats"></a>
<h3 class="section">3.1 FFM, FFM2 formats<span class="pull-right"><a class="anchor hidden-xs" href="#FFM_002c-FFM2-formats" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-FFM_002c-FFM2-formats" aria-hidden="true">TOC</a></span></h3>
<p>FFM and FFM2 are formats used by ffserver. They allow storing a wide variety of
video and audio streams and encoding options, and can store a moving time segment
of an infinite movie or a whole movie.
</p>
<p>FFM is version specific, and there is limited compatibility of FFM files
generated by one version of ffmpeg/ffserver and another version of
ffmpeg/ffserver. It may work but it is not guaranteed to work.
</p>
<p>FFM2 is extensible while maintaining compatibility and should work between
differing versions of tools. FFM2 is the default.
</p>
<a name="Status-stream"></a>
<h3 class="section">3.2 Status stream<span class="pull-right"><a class="anchor hidden-xs" href="#Status-stream" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Status-stream" aria-hidden="true">TOC</a></span></h3>
<p><code>ffserver</code> supports an HTTP interface which exposes the
current status of the server.
</p>
<p>Simply point your browser to the address of the special status stream
specified in the configuration file.
</p>
<p>For example if you have:
</p><div class="example">
<pre class="example"><Stream status.html>
Format status
# Only allow local people to get the status
ACL allow localhost
ACL allow 192.168.0.0 192.168.255.255
</Stream>
</pre></div>
<p>then the server will post a page with the status information when
the special stream <samp>status.html</samp> is requested.
</p>
<a name="How-do-I-make-it-work_003f"></a>
<h3 class="section">3.3 How do I make it work?<span class="pull-right"><a class="anchor hidden-xs" href="#How-do-I-make-it-work_003f" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-How-do-I-make-it-work_003f" aria-hidden="true">TOC</a></span></h3>
<p>As a simple test, just run the following two command lines where INPUTFILE
is some file which you can decode with ffmpeg:
</p>
<div class="example">
<pre class="example">ffserver -f doc/ffserver.conf &
ffmpeg -i INPUTFILE http://localhost:8090/feed1.ffm
</pre></div>
<p>At this point you should be able to go to your Windows machine and fire up
Windows Media Player (WMP). Go to Open URL and enter
</p>
<div class="example">
<pre class="example"> http://<linuxbox>:8090/test.asf
</pre></div>
<p>You should (after a short delay) see video and hear audio.
</p>
<p>WARNING: trying to stream test1.mpg doesn’t work with WMP as it tries to
transfer the entire file before starting to play.
The same is true of AVI files.
</p>
<p>You should edit the <samp>ffserver.conf</samp> file to suit your needs (in
terms of frame rates etc). Then install <code>ffserver</code> and
<code>ffmpeg</code>, write a script to start them up, and off you go.
</p>
<a name="What-else-can-it-do_003f"></a>
<h3 class="section">3.4 What else can it do?<span class="pull-right"><a class="anchor hidden-xs" href="#What-else-can-it-do_003f" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-What-else-can-it-do_003f" aria-hidden="true">TOC</a></span></h3>
<p>You can replay video from .ffm files that was recorded earlier.
However, there are a number of caveats, including the fact that the
ffserver parameters must match the original parameters used to record the
file. If they do not, then ffserver deletes the file before recording into it.
(Now that I write this, it seems broken).
</p>
<p>You can fiddle with many of the codec choices and encoding parameters, and
there are a bunch more parameters that you cannot control. Post a message
to the mailing list if there are some ’must have’ parameters. Look in
ffserver.conf for a list of the currently available controls.
</p>
<p>It will automatically generate the ASX or RAM files that are often used
in browsers. These files are actually redirections to the underlying ASF
or RM file. The reason for this is that the browser often fetches the
entire file before starting up the external viewer. The redirection files
are very small and can be transferred quickly. [The stream itself is
often ’infinite’ and thus the browser tries to download it and never
finishes.]
</p>
<a name="Tips"></a>
<h3 class="section">3.5 Tips<span class="pull-right"><a class="anchor hidden-xs" href="#Tips" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Tips" aria-hidden="true">TOC</a></span></h3>
<p>* When you connect to a live stream, most players (WMP, RA, etc) want to
buffer a certain number of seconds of material so that they can display the
signal continuously. However, ffserver (by default) starts sending data
in realtime. This means that there is a pause of a few seconds while the
buffering is being done by the player. The good news is that this can be
cured by adding a ’?buffer=5’ to the end of the URL. This means that the
stream should start 5 seconds in the past – and so the first 5 seconds
of the stream are sent as fast as the network will allow. It will then
slow down to real time. This noticeably improves the startup experience.
</p>
<p>You can also add a ’Preroll 15’ statement into the ffserver.conf that will
add the 15 second prebuffering on all requests that do not otherwise
specify a time. In addition, ffserver will skip frames until a key_frame
is found. This further reduces the startup delay by not transferring data
that will be discarded.
</p>
<a name="Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f"></a>
<h3 class="section">3.6 Why does the ?buffer / Preroll stop working after a time?<span class="pull-right"><a class="anchor hidden-xs" href="#Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f" aria-hidden="true">TOC</a></span></h3>
<p>It turns out that (on my machine at least) the number of frames successfully
grabbed is marginally less than the number that ought to be grabbed. This
means that the timestamp in the encoded data stream gets behind realtime.
This means that if you say ’Preroll 10’, then when the stream gets 10
or more seconds behind, there is no Preroll left.
</p>
<p>Fixing this requires a change in the internals of how timestamps are
handled.
</p>
<a name="Does-the-_003fdate_003d-stuff-work_002e"></a>
<h3 class="section">3.7 Does the <code>?date=</code> stuff work.<span class="pull-right"><a class="anchor hidden-xs" href="#Does-the-_003fdate_003d-stuff-work_002e" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Does-the-_003fdate_003d-stuff-work_002e" aria-hidden="true">TOC</a></span></h3>
<p>Yes (subject to the limitation outlined above). Also note that whenever you
start ffserver, it deletes the ffm file (if any parameters have changed),
thus wiping out what you had recorded before.
</p>
<p>The format of the <code>?date=xxxxxx</code> is fairly flexible. You should use one
of the following formats (the ’T’ is literal):
</p>
<div class="example">
<pre class="example">* YYYY-MM-DDTHH:MM:SS (localtime)
* YYYY-MM-DDTHH:MM:SSZ (UTC)
</pre></div>
<p>You can omit the YYYY-MM-DD, and then it refers to the current day. However
note that ‘<samp>?date=16:00:00</samp>’ refers to 16:00 on the current day – this
may be in the future and so is unlikely to be useful.
</p>
<p>You use this by adding the ?date= to the end of the URL for the stream.
For example: ‘<samp>http://localhost:8080/test.asf?date=2002-07-26T23:05:00</samp>’.
</p>
<a name="Options"></a>
<h2 class="chapter">4 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options" aria-hidden="true">TOC</a></span></h2>
<p>All the numerical options, if not specified otherwise, accept a string
representing a number as input, which may be followed by one of the SI
unit prefixes, for example: ’K’, ’M’, or ’G’.
</p>
<p>If ’i’ is appended to the SI unit prefix, the complete prefix will be
interpreted as a unit prefix for binary multiples, which are based on
powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
prefix multiplies the value by 8. This allows using, for example:
’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
</p>
<p>Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing
the option name with "no". For example using "-nofoo"
will set the boolean option with name "foo" to false.
</p>
<a name="Stream-specifiers"></a><a name="Stream-specifiers-1"></a>
<h3 class="section">4.1 Stream specifiers<span class="pull-right"><a class="anchor hidden-xs" href="#Stream-specifiers-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Stream-specifiers-1" aria-hidden="true">TOC</a></span></h3>
<p>Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
are used to precisely specify which stream(s) a given option belongs to.
</p>
<p>A stream specifier is a string generally appended to the option name and
separated from it by a colon. E.g. <code>-codec:a:1 ac3</code> contains the
<code>a:1</code> stream specifier, which matches the second audio stream. Therefore, it
would select the ac3 codec for the second audio stream.
</p>
<p>A stream specifier can match several streams, so that the option is applied to all
of them. E.g. the stream specifier in <code>-b:a 128k</code> matches all audio
streams.
</p>
<p>An empty stream specifier matches all streams. For example, <code>-codec copy</code>
or <code>-codec: copy</code> would copy all the streams without reencoding.
</p>
<p>Possible forms of stream specifiers are:
</p><dl compact="compact">
<dt><samp><var>stream_index</var></samp></dt>
<dd><p>Matches the stream with this index. E.g. <code>-threads:1 4</code> would set the
thread count for the second stream to 4.
</p></dd>
<dt><samp><var>stream_type</var>[:<var>stream_index</var>]</samp></dt>
<dd><p><var>stream_type</var> is one of following: ’v’ or ’V’ for video, ’a’ for audio, ’s’
for subtitle, ’d’ for data, and ’t’ for attachments. ’v’ matches all video
streams, ’V’ only matches video streams which are not attached pictures, video
thumbnails or cover arts. If <var>stream_index</var> is given, then it matches
stream number <var>stream_index</var> of this type. Otherwise, it matches all
streams of this type.
</p></dd>
<dt><samp>p:<var>program_id</var>[:<var>stream_index</var>]</samp></dt>
<dd><p>If <var>stream_index</var> is given, then it matches the stream with number <var>stream_index</var>
in the program with the id <var>program_id</var>. Otherwise, it matches all streams in the
program.
</p></dd>
<dt><samp>#<var>stream_id</var> or i:<var>stream_id</var></samp></dt>
<dd><p>Match the stream by stream id (e.g. PID in MPEG-TS container).
</p></dd>
<dt><samp>m:<var>key</var>[:<var>value</var>]</samp></dt>
<dd><p>Matches streams with the metadata tag <var>key</var> having the specified value. If
<var>value</var> is not given, matches streams that contain the given tag with any
value.
</p></dd>
<dt><samp>u</samp></dt>
<dd><p>Matches streams with usable configuration, the codec must be defined and the
essential information such as video dimension or audio sample rate must be present.
</p>
<p>Note that in <code>ffmpeg</code>, matching by metadata will only work properly for
input files.
</p></dd>
</dl>
<a name="Generic-options"></a>
<h3 class="section">4.2 Generic options<span class="pull-right"><a class="anchor hidden-xs" href="#Generic-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Generic-options" aria-hidden="true">TOC</a></span></h3>
<p>These options are shared amongst the ff* tools.
</p>
<dl compact="compact">
<dt><samp>-L</samp></dt>
<dd><p>Show license.
</p>
</dd>
<dt><samp>-h, -?, -help, --help [<var>arg</var>]</samp></dt>
<dd><p>Show help. An optional parameter may be specified to print help about a specific
item. If no argument is specified, only basic (non advanced) tool
options are shown.
</p>
<p>Possible values of <var>arg</var> are:
</p><dl compact="compact">
<dt><samp>long</samp></dt>
<dd><p>Print advanced tool options in addition to the basic tool options.
</p>
</dd>
<dt><samp>full</samp></dt>
<dd><p>Print complete list of options, including shared and private options
for encoders, decoders, demuxers, muxers, filters, etc.
</p>
</dd>
<dt><samp>decoder=<var>decoder_name</var></samp></dt>
<dd><p>Print detailed information about the decoder named <var>decoder_name</var>. Use the
<samp>-decoders</samp> option to get a list of all decoders.
</p>
</dd>
<dt><samp>encoder=<var>encoder_name</var></samp></dt>
<dd><p>Print detailed information about the encoder named <var>encoder_name</var>. Use the
<samp>-encoders</samp> option to get a list of all encoders.
</p>
</dd>
<dt><samp>demuxer=<var>demuxer_name</var></samp></dt>
<dd><p>Print detailed information about the demuxer named <var>demuxer_name</var>. Use the
<samp>-formats</samp> option to get a list of all demuxers and muxers.
</p>
</dd>
<dt><samp>muxer=<var>muxer_name</var></samp></dt>
<dd><p>Print detailed information about the muxer named <var>muxer_name</var>. Use the
<samp>-formats</samp> option to get a list of all muxers and demuxers.
</p>
</dd>
<dt><samp>filter=<var>filter_name</var></samp></dt>
<dd><p>Print detailed information about the filter name <var>filter_name</var>. Use the
<samp>-filters</samp> option to get a list of all filters.
</p></dd>
</dl>
</dd>
<dt><samp>-version</samp></dt>
<dd><p>Show version.
</p>
</dd>
<dt><samp>-formats</samp></dt>
<dd><p>Show available formats (including devices).
</p>
</dd>
<dt><samp>-devices</samp></dt>
<dd><p>Show available devices.
</p>
</dd>
<dt><samp>-codecs</samp></dt>
<dd><p>Show all codecs known to libavcodec.
</p>
<p>Note that the term ’codec’ is used throughout this documentation as a shortcut
for what is more correctly called a media bitstream format.
</p>
</dd>
<dt><samp>-decoders</samp></dt>
<dd><p>Show available decoders.
</p>
</dd>
<dt><samp>-encoders</samp></dt>
<dd><p>Show all available encoders.
</p>
</dd>
<dt><samp>-bsfs</samp></dt>
<dd><p>Show available bitstream filters.
</p>
</dd>
<dt><samp>-protocols</samp></dt>
<dd><p>Show available protocols.
</p>
</dd>
<dt><samp>-filters</samp></dt>
<dd><p>Show available libavfilter filters.
</p>
</dd>
<dt><samp>-pix_fmts</samp></dt>
<dd><p>Show available pixel formats.
</p>
</dd>
<dt><samp>-sample_fmts</samp></dt>
<dd><p>Show available sample formats.
</p>
</dd>
<dt><samp>-layouts</samp></dt>
<dd><p>Show channel names and standard channel layouts.
</p>
</dd>
<dt><samp>-colors</samp></dt>
<dd><p>Show recognized color names.
</p>
</dd>
<dt><samp>-sources <var>device</var>[,<var>opt1</var>=<var>val1</var>[,<var>opt2</var>=<var>val2</var>]...]</samp></dt>
<dd><p>Show autodetected sources of the intput device.
Some devices may provide system-dependent source names that cannot be autodetected.
The returned list cannot be assumed to be always complete.
</p><div class="example">
<pre class="example">ffmpeg -sources pulse,server=192.168.0.4
</pre></div>
</dd>
<dt><samp>-sinks <var>device</var>[,<var>opt1</var>=<var>val1</var>[,<var>opt2</var>=<var>val2</var>]...]</samp></dt>
<dd><p>Show autodetected sinks of the output device.
Some devices may provide system-dependent sink names that cannot be autodetected.
The returned list cannot be assumed to be always complete.
</p><div class="example">
<pre class="example">ffmpeg -sinks pulse,server=192.168.0.4
</pre></div>
</dd>
<dt><samp>-loglevel [repeat+]<var>loglevel</var> | -v [repeat+]<var>loglevel</var></samp></dt>
<dd><p>Set the logging level used by the library.
Adding "repeat+" indicates that repeated log output should not be compressed
to the first line and the "Last message repeated n times" line will be
omitted. "repeat" can also be used alone.
If "repeat" is used alone, and with no prior loglevel set, the default
loglevel will be used. If multiple loglevel parameters are given, using
’repeat’ will not change the loglevel.
<var>loglevel</var> is a string or a number containing one of the following values:
</p><dl compact="compact">
<dt>‘<samp>quiet, -8</samp>’</dt>
<dd><p>Show nothing at all; be silent.
</p></dd>
<dt>‘<samp>panic, 0</samp>’</dt>
<dd><p>Only show fatal errors which could lead the process to crash, such as
and assert failure. This is not currently used for anything.
</p></dd>
<dt>‘<samp>fatal, 8</samp>’</dt>
<dd><p>Only show fatal errors. These are errors after which the process absolutely
cannot continue after.
</p></dd>
<dt>‘<samp>error, 16</samp>’</dt>
<dd><p>Show all errors, including ones which can be recovered from.
</p></dd>
<dt>‘<samp>warning, 24</samp>’</dt>
<dd><p>Show all warnings and errors. Any message related to possibly
incorrect or unexpected events will be shown.
</p></dd>
<dt>‘<samp>info, 32</samp>’</dt>
<dd><p>Show informative messages during processing. This is in addition to
warnings and errors. This is the default value.
</p></dd>
<dt>‘<samp>verbose, 40</samp>’</dt>
<dd><p>Same as <code>info</code>, except more verbose.
</p></dd>
<dt>‘<samp>debug, 48</samp>’</dt>
<dd><p>Show everything, including debugging information.
</p></dd>
<dt>‘<samp>trace, 56</samp>’</dt>
</dl>
<p>By default the program logs to stderr, if coloring is supported by the
terminal, colors are used to mark errors and warnings. Log coloring
can be disabled setting the environment variable
<code>AV_LOG_FORCE_NOCOLOR</code> or <code>NO_COLOR</code>, or can be forced setting
the environment variable <code>AV_LOG_FORCE_COLOR</code>.
The use of the environment variable <code>NO_COLOR</code> is deprecated and
will be dropped in a following FFmpeg version.
</p>
</dd>
<dt><samp>-report</samp></dt>
<dd><p>Dump full command line and console output to a file named
<code><var>program</var>-<var>YYYYMMDD</var>-<var>HHMMSS</var>.log</code> in the current
directory.
This file can be useful for bug reports.
It also implies <code>-loglevel verbose</code>.
</p>
<p>Setting the environment variable <code>FFREPORT</code> to any value has the
same effect. If the value is a ’:’-separated key=value sequence, these
options will affect the report; option values must be escaped if they
contain special characters or the options delimiter ’:’ (see the
“Quoting and escaping” section in the ffmpeg-utils manual).
</p>
<p>The following options are recognized:
</p><dl compact="compact">
<dt><samp>file</samp></dt>
<dd><p>set the file name to use for the report; <code>%p</code> is expanded to the name
of the program, <code>%t</code> is expanded to a timestamp, <code>%%</code> is expanded
to a plain <code>%</code>
</p></dd>
<dt><samp>level</samp></dt>
<dd><p>set the log verbosity level using a numerical value (see <code>-loglevel</code>).
</p></dd>
</dl>
<p>For example, to output a report to a file named <samp>ffreport.log</samp>
using a log level of <code>32</code> (alias for log level <code>info</code>):
</p>
<div class="example">
<pre class="example">FFREPORT=file=ffreport.log:level=32 ffmpeg -i input output
</pre></div>
<p>Errors in parsing the environment variable are not fatal, and will not
appear in the report.
</p>
</dd>
<dt><samp>-hide_banner</samp></dt>
<dd><p>Suppress printing banner.
</p>
<p>All FFmpeg tools will normally show a copyright notice, build options
and library versions. This option can be used to suppress printing
this information.
</p>
</dd>
<dt><samp>-cpuflags flags (<em>global</em>)</samp></dt>
<dd><p>Allows setting and clearing cpu flags. This option is intended
for testing. Do not use it unless you know what you’re doing.
</p><div class="example">
<pre class="example">ffmpeg -cpuflags -sse+mmx ...
ffmpeg -cpuflags mmx ...
ffmpeg -cpuflags 0 ...
</pre></div>
<p>Possible flags for this option are:
</p><dl compact="compact">
<dt>‘<samp>x86</samp>’</dt>
<dd><dl compact="compact">
<dt>‘<samp>mmx</samp>’</dt>
<dt>‘<samp>mmxext</samp>’</dt>
<dt>‘<samp>sse</samp>’</dt>
<dt>‘<samp>sse2</samp>’</dt>
<dt>‘<samp>sse2slow</samp>’</dt>
<dt>‘<samp>sse3</samp>’</dt>
<dt>‘<samp>sse3slow</samp>’</dt>
<dt>‘<samp>ssse3</samp>’</dt>
<dt>‘<samp>atom</samp>’</dt>
<dt>‘<samp>sse4.1</samp>’</dt>
<dt>‘<samp>sse4.2</samp>’</dt>
<dt>‘<samp>avx</samp>’</dt>
<dt>‘<samp>avx2</samp>’</dt>
<dt>‘<samp>xop</samp>’</dt>
<dt>‘<samp>fma3</samp>’</dt>
<dt>‘<samp>fma4</samp>’</dt>
<dt>‘<samp>3dnow</samp>’</dt>
<dt>‘<samp>3dnowext</samp>’</dt>
<dt>‘<samp>bmi1</samp>’</dt>
<dt>‘<samp>bmi2</samp>’</dt>
<dt>‘<samp>cmov</samp>’</dt>
</dl>
</dd>
<dt>‘<samp>ARM</samp>’</dt>
<dd><dl compact="compact">
<dt>‘<samp>armv5te</samp>’</dt>
<dt>‘<samp>armv6</samp>’</dt>
<dt>‘<samp>armv6t2</samp>’</dt>
<dt>‘<samp>vfp</samp>’</dt>
<dt>‘<samp>vfpv3</samp>’</dt>
<dt>‘<samp>neon</samp>’</dt>
<dt>‘<samp>setend</samp>’</dt>
</dl>
</dd>
<dt>‘<samp>AArch64</samp>’</dt>
<dd><dl compact="compact">
<dt>‘<samp>armv8</samp>’</dt>
<dt>‘<samp>vfp</samp>’</dt>
<dt>‘<samp>neon</samp>’</dt>
</dl>
</dd>
<dt>‘<samp>PowerPC</samp>’</dt>
<dd><dl compact="compact">
<dt>‘<samp>altivec</samp>’</dt>
</dl>
</dd>
<dt>‘<samp>Specific Processors</samp>’</dt>
<dd><dl compact="compact">
<dt>‘<samp>pentium2</samp>’</dt>
<dt>‘<samp>pentium3</samp>’</dt>
<dt>‘<samp>pentium4</samp>’</dt>
<dt>‘<samp>k6</samp>’</dt>
<dt>‘<samp>k62</samp>’</dt>
<dt>‘<samp>athlon</samp>’</dt>
<dt>‘<samp>athlonxp</samp>’</dt>
<dt>‘<samp>k8</samp>’</dt>
</dl>
</dd>
</dl>
</dd>
<dt><samp>-opencl_bench</samp></dt>
<dd><p>This option is used to benchmark all available OpenCL devices and print the
results. This option is only available when FFmpeg has been compiled with
<code>--enable-opencl</code>.
</p>
<p>When FFmpeg is configured with <code>--enable-opencl</code>, the options for the
global OpenCL context are set via <samp>-opencl_options</samp>. See the
"OpenCL Options" section in the ffmpeg-utils manual for the complete list of
supported options. Amongst others, these options include the ability to select
a specific platform and device to run the OpenCL code on. By default, FFmpeg
will run on the first device of the first platform. While the options for the
global OpenCL context provide flexibility to the user in selecting the OpenCL
device of their choice, most users would probably want to select the fastest
OpenCL device for their system.
</p>
<p>This option assists the selection of the most efficient configuration by
identifying the appropriate device for the user’s system. The built-in
benchmark is run on all the OpenCL devices and the performance is measured for
each device. The devices in the results list are sorted based on their
performance with the fastest device listed first. The user can subsequently
invoke <code>ffmpeg</code> using the device deemed most appropriate via
<samp>-opencl_options</samp> to obtain the best performance for the OpenCL
accelerated code.
</p>
<p>Typical usage to use the fastest OpenCL device involve the following steps.
</p>
<p>Run the command:
</p><div class="example">
<pre class="example">ffmpeg -opencl_bench
</pre></div>
<p>Note down the platform ID (<var>pidx</var>) and device ID (<var>didx</var>) of the first
i.e. fastest device in the list.
Select the platform and device using the command:
</p><div class="example">
<pre class="example">ffmpeg -opencl_options platform_idx=<var>pidx</var>:device_idx=<var>didx</var> ...
</pre></div>
</dd>
<dt><samp>-opencl_options options (<em>global</em>)</samp></dt>
<dd><p>Set OpenCL environment options. This option is only available when
FFmpeg has been compiled with <code>--enable-opencl</code>.
</p>
<p><var>options</var> must be a list of <var>key</var>=<var>value</var> option pairs
separated by ’:’. See the “OpenCL Options” section in the
ffmpeg-utils manual for the list of supported options.
</p></dd>
</dl>
<a name="AVOptions"></a>
<h3 class="section">4.3 AVOptions<span class="pull-right"><a class="anchor hidden-xs" href="#AVOptions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-AVOptions" aria-hidden="true">TOC</a></span></h3>
<p>These options are provided directly by the libavformat, libavdevice and
libavcodec libraries. To see the list of available AVOptions, use the
<samp>-help</samp> option. They are separated into two categories:
</p><dl compact="compact">
<dt><samp>generic</samp></dt>
<dd><p>These options can be set for any container, codec or device. Generic options
are listed under AVFormatContext options for containers/devices and under
AVCodecContext options for codecs.
</p></dd>
<dt><samp>private</samp></dt>
<dd><p>These options are specific to the given container, device or codec. Private
options are listed under their corresponding containers/devices/codecs.
</p></dd>
</dl>
<p>For example to write an ID3v2.3 header instead of a default ID3v2.4 to
an MP3 file, use the <samp>id3v2_version</samp> private option of the MP3
muxer:
</p><div class="example">
<pre class="example">ffmpeg -i input.flac -id3v2_version 3 out.mp3
</pre></div>
<p>All codec AVOptions are per-stream, and thus a stream specifier
should be attached to them.
</p>
<p>Note: the <samp>-nooption</samp> syntax cannot be used for boolean
AVOptions, use <samp>-option 0</samp>/<samp>-option 1</samp>.
</p>
<p>Note: the old undocumented way of specifying per-stream AVOptions by
prepending v/a/s to the options name is now obsolete and will be
removed soon.
</p>
<a name="Main-options"></a>
<h3 class="section">4.4 Main options<span class="pull-right"><a class="anchor hidden-xs" href="#Main-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Main-options" aria-hidden="true">TOC</a></span></h3>
<dl compact="compact">
<dt><samp>-f <var>configfile</var></samp></dt>
<dd><p>Read configuration file <samp>configfile</samp>. If not specified it will
read by default from <samp>/etc/ffserver.conf</samp>.
</p>
</dd>
<dt><samp>-n</samp></dt>
<dd><p>Enable no-launch mode. This option disables all the <code>Launch</code>
directives within the various <code><Feed></code> sections. Since
<code>ffserver</code> will not launch any <code>ffmpeg</code> instances, you
will have to launch them manually.
</p>
</dd>
<dt><samp>-d</samp></dt>
<dd><p>Enable debug mode. This option increases log verbosity, and directs
log messages to stdout. When specified, the <samp>CustomLog</samp> option
is ignored.
</p></dd>
</dl>
<a name="Configuration-file-syntax"></a>
<h2 class="chapter">5 Configuration file syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Configuration-file-syntax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Configuration-file-syntax" aria-hidden="true">TOC</a></span></h2>
<p><code>ffserver</code> reads a configuration file containing global
options and settings for each stream and feed.
</p>
<p>The configuration file consists of global options and dedicated
sections, which must be introduced by "<<var>SECTION_NAME</var>
<var>ARGS</var>>" on a separate line and must be terminated by a line in
the form "</<var>SECTION_NAME</var>>". <var>ARGS</var> is optional.
</p>
<p>Currently the following sections are recognized: ‘<samp>Feed</samp>’,
‘<samp>Stream</samp>’, ‘<samp>Redirect</samp>’.
</p>
<p>A line starting with <code>#</code> is ignored and treated as a comment.
</p>
<p>Name of options and sections are case-insensitive.
</p>
<a name="ACL-syntax"></a>
<h3 class="section">5.1 ACL syntax<span class="pull-right"><a class="anchor hidden-xs" href="#ACL-syntax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ACL-syntax" aria-hidden="true">TOC</a></span></h3>
<p>An ACL (Access Control List) specifies the address which are allowed
to access a given stream, or to write a given feed.
</p>
<p>It accepts the folling forms
</p><ul>
<li> Allow/deny access to <var>address</var>.
<div class="example">
<pre class="example">ACL ALLOW <address>
ACL DENY <address>
</pre></div>
</li><li> Allow/deny access to ranges of addresses from <var>first_address</var> to
<var>last_address</var>.
<div class="example">
<pre class="example">ACL ALLOW <first_address> <last_address>
ACL DENY <first_address> <last_address>
</pre></div>
</li></ul>
<p>You can repeat the ACL allow/deny as often as you like. It is on a per
stream basis. The first match defines the action. If there are no matches,
then the default is the inverse of the last ACL statement.
</p>
<p>Thus ’ACL allow localhost’ only allows access from localhost.
’ACL deny 1.0.0.0 1.255.255.255’ would deny the whole of network 1 and
allow everybody else.
</p>
<a name="Global-options"></a>
<h3 class="section">5.2 Global options<span class="pull-right"><a class="anchor hidden-xs" href="#Global-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Global-options" aria-hidden="true">TOC</a></span></h3>
<dl compact="compact">
<dt><samp>HTTPPort <var>port_number</var></samp></dt>
<dt><samp>Port <var>port_number</var></samp></dt>
<dt><samp>RTSPPort <var>port_number</var></samp></dt>
<dd>
<p><var>HTTPPort</var> sets the HTTP server listening TCP port number,
<var>RTSPPort</var> sets the RTSP server listening TCP port number.
</p>
<p><var>Port</var> is the equivalent of <var>HTTPPort</var> and is deprecated.
</p>
<p>You must select a different port from your standard HTTP web server if
it is running on the same computer.
</p>
<p>If not specified, no corresponding server will be created.
</p>
</dd>
<dt><samp>HTTPBindAddress <var>ip_address</var></samp></dt>
<dt><samp>BindAddress <var>ip_address</var></samp></dt>
<dt><samp>RTSPBindAddress <var>ip_address</var></samp></dt>
<dd><p>Set address on which the HTTP/RTSP server is bound. Only useful if you
have several network interfaces.
</p>
<p><var>BindAddress</var> is the equivalent of <var>HTTPBindAddress</var> and is
deprecated.
</p>
</dd>
<dt><samp>MaxHTTPConnections <var>n</var></samp></dt>
<dd><p>Set number of simultaneous HTTP connections that can be handled. It
has to be defined <em>before</em> the <samp>MaxClients</samp> parameter,
since it defines the <samp>MaxClients</samp> maximum limit.
</p>
<p>Default value is 2000.
</p>
</dd>
<dt><samp>MaxClients <var>n</var></samp></dt>
<dd><p>Set number of simultaneous requests that can be handled. Since
<code>ffserver</code> is very fast, it is more likely that you will want
to leave this high and use <samp>MaxBandwidth</samp>.
</p>
<p>Default value is 5.
</p>
</dd>
<dt><samp>MaxBandwidth <var>kbps</var></samp></dt>
<dd><p>Set the maximum amount of kbit/sec that you are prepared to consume
when streaming to clients.
</p>
<p>Default value is 1000.
</p>
</dd>
<dt><samp>CustomLog <var>filename</var></samp></dt>
<dd><p>Set access log file (uses standard Apache log file format). ’-’ is the
standard output.
</p>
<p>If not specified <code>ffserver</code> will produce no log.
</p>
<p>In case the commandline option <samp>-d</samp> is specified this option is
ignored, and the log is written to standard output.
</p>
</dd>
<dt><samp>NoDaemon</samp></dt>
<dd><p>Set no-daemon mode. This option is currently ignored since now
<code>ffserver</code> will always work in no-daemon mode, and is
deprecated.
</p>
</dd>
<dt><samp>UseDefaults</samp></dt>
<dt><samp>NoDefaults</samp></dt>
<dd><p>Control whether default codec options are used for the all streams or not.
Each stream may overwrite this setting for its own. Default is <var>UseDefaults</var>.
The lastest occurrence overrides previous if multiple definitions.
</p></dd>
</dl>
<a name="Feed-section"></a>
<h3 class="section">5.3 Feed section<span class="pull-right"><a class="anchor hidden-xs" href="#Feed-section" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Feed-section" aria-hidden="true">TOC</a></span></h3>
<p>A Feed section defines a feed provided to <code>ffserver</code>.
</p>
<p>Each live feed contains one video and/or audio sequence coming from an
<code>ffmpeg</code> encoder or another <code>ffserver</code>. This sequence
may be encoded simultaneously with several codecs at several
resolutions.
</p>
<p>A feed instance specification is introduced by a line in the form:
</p><div class="example">
<pre class="example"><Feed FEED_FILENAME>
</pre></div>
<p>where <var>FEED_FILENAME</var> specifies the unique name of the FFM stream.
</p>
<p>The following options are recognized within a Feed section.
</p>
<dl compact="compact">
<dt><samp>File <var>filename</var></samp></dt>
<dt><samp>ReadOnlyFile <var>filename</var></samp></dt>
<dd><p>Set the path where the feed file is stored on disk.
</p>
<p>If not specified, the <samp>/tmp/FEED.ffm</samp> is assumed, where
<var>FEED</var> is the feed name.
</p>
<p>If <samp>ReadOnlyFile</samp> is used the file is marked as read-only and
it will not be deleted or updated.
</p>
</dd>
<dt><samp>Truncate</samp></dt>
<dd><p>Truncate the feed file, rather than appending to it. By default
<code>ffserver</code> will append data to the file, until the maximum
file size value is reached (see <samp>FileMaxSize</samp> option).
</p>
</dd>
<dt><samp>FileMaxSize <var>size</var></samp></dt>
<dd><p>Set maximum size of the feed file in bytes. 0 means unlimited. The
postfixes <code>K</code> (2^10), <code>M</code> (2^20), and <code>G</code> (2^30) are
recognized.
</p>
<p>Default value is 5M.
</p>
</dd>
<dt><samp>Launch <var>args</var></samp></dt>
<dd><p>Launch an <code>ffmpeg</code> command when creating <code>ffserver</code>.
</p>
<p><var>args</var> must be a sequence of arguments to be provided to an
<code>ffmpeg</code> instance. The first provided argument is ignored, and
it is replaced by a path with the same dirname of the <code>ffserver</code>
instance, followed by the remaining argument and terminated with a
path corresponding to the feed.
</p>
<p>When the launched process exits, <code>ffserver</code> will launch
another program instance.
</p>
<p>In case you need a more complex <code>ffmpeg</code> configuration,
e.g. if you need to generate multiple FFM feeds with a single
<code>ffmpeg</code> instance, you should launch <code>ffmpeg</code> by hand.
</p>
<p>This option is ignored in case the commandline option <samp>-n</samp> is
specified.
</p>
</dd>
<dt><samp>ACL <var>spec</var></samp></dt>
<dd><p>Specify the list of IP address which are allowed or denied to write
the feed. Multiple ACL options can be specified.
</p></dd>
</dl>
<a name="Stream-section"></a>
<h3 class="section">5.4 Stream section<span class="pull-right"><a class="anchor hidden-xs" href="#Stream-section" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Stream-section" aria-hidden="true">TOC</a></span></h3>
<p>A Stream section defines a stream provided by <code>ffserver</code>, and
identified by a single name.
</p>
<p>The stream is sent when answering a request containing the stream
name.
</p>
<p>A stream section must be introduced by the line:
</p><div class="example">
<pre class="example"><Stream STREAM_NAME>
</pre></div>
<p>where <var>STREAM_NAME</var> specifies the unique name of the stream.
</p>
<p>The following options are recognized within a Stream section.
</p>
<p>Encoding options are marked with the <em>encoding</em> tag, and they are
used to set the encoding parameters, and are mapped to libavcodec
encoding options. Not all encoding options are supported, in
particular it is not possible to set encoder private options. In order
to override the encoding options specified by <code>ffserver</code>, you
can use the <code>ffmpeg</code> <samp>override_ffserver</samp> commandline
option.
</p>
<p>Only one of the <samp>Feed</samp> and <samp>File</samp> options should be set.
</p>
<dl compact="compact">
<dt><samp>Feed <var>feed_name</var></samp></dt>
<dd><p>Set the input feed. <var>feed_name</var> must correspond to an existing
feed defined in a <code>Feed</code> section.
</p>
<p>When this option is set, encoding options are used to setup the
encoding operated by the remote <code>ffmpeg</code> process.
</p>
</dd>
<dt><samp>File <var>filename</var></samp></dt>
<dd><p>Set the filename of the pre-recorded input file to stream.
</p>
<p>When this option is set, encoding options are ignored and the input
file content is re-streamed as is.
</p>
</dd>
<dt><samp>Format <var>format_name</var></samp></dt>
<dd><p>Set the format of the output stream.
</p>
<p>Must be the name of a format recognized by FFmpeg. If set to
‘<samp>status</samp>’, it is treated as a status stream.
</p>
</dd>
<dt><samp>InputFormat <var>format_name</var></samp></dt>
<dd><p>Set input format. If not specified, it is automatically guessed.
</p>
</dd>
<dt><samp>Preroll <var>n</var></samp></dt>
<dd><p>Set this to the number of seconds backwards in time to start. Note that
most players will buffer 5-10 seconds of video, and also you need to allow
for a keyframe to appear in the data stream.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>StartSendOnKey</samp></dt>
<dd><p>Do not send stream until it gets the first key frame. By default
<code>ffserver</code> will send data immediately.
</p>
</dd>
<dt><samp>MaxTime <var>n</var></samp></dt>
<dd><p>Set the number of seconds to run. This value set the maximum duration
of the stream a client will be able to receive.
</p>
<p>A value of 0 means that no limit is set on the stream duration.
</p>
</dd>
<dt><samp>ACL <var>spec</var></samp></dt>
<dd><p>Set ACL for the stream.
</p>
</dd>
<dt><samp>DynamicACL <var>spec</var></samp></dt>
<dt><samp>RTSPOption <var>option</var></samp></dt>
<dt><samp>MulticastAddress <var>address</var></samp></dt>
<dt><samp>MulticastPort <var>port</var></samp></dt>
<dt><samp>MulticastTTL <var>integer</var></samp></dt>
<dt><samp>NoLoop</samp></dt>
<dt><samp>FaviconURL <var>url</var></samp></dt>
<dd><p>Set favicon (favourite icon) for the server status page. It is ignored
for regular streams.
</p>
</dd>
<dt><samp>Author <var>value</var></samp></dt>
<dt><samp>Comment <var>value</var></samp></dt>
<dt><samp>Copyright <var>value</var></samp></dt>
<dt><samp>Title <var>value</var></samp></dt>
<dd><p>Set metadata corresponding to the option. All these options are
deprecated in favor of <samp>Metadata</samp>.
</p>
</dd>
<dt><samp>Metadata <var>key</var> <var>value</var></samp></dt>
<dd><p>Set metadata value on the output stream.
</p>
</dd>
<dt><samp>UseDefaults</samp></dt>
<dt><samp>NoDefaults</samp></dt>
<dd><p>Control whether default codec options are used for the stream or not.
Default is <var>UseDefaults</var> unless disabled globally.
</p>
</dd>
<dt><samp>NoAudio</samp></dt>
<dt><samp>NoVideo</samp></dt>
<dd><p>Suppress audio/video.
</p>
</dd>
<dt><samp>AudioCodec <var>codec_name</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set audio codec.
</p>
</dd>
<dt><samp>AudioBitRate <var>rate</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set bitrate for the audio stream in kbits per second.
</p>
</dd>
<dt><samp>AudioChannels <var>n</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set number of audio channels.
</p>
</dd>
<dt><samp>AudioSampleRate <var>n</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set sampling frequency for audio. When using low bitrates, you should
lower this frequency to 22050 or 11025. The supported frequencies
depend on the selected audio codec.
</p>
</dd>
<dt><samp>AVOptionAudio [<var>codec</var>:]<var>option</var> <var>value</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set generic or private option for audio stream.
Private option must be prefixed with codec name or codec must be defined before.
</p>
</dd>
<dt><samp>AVPresetAudio <var>preset</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set preset for audio stream.
</p>
</dd>
<dt><samp>VideoCodec <var>codec_name</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video codec.
</p>
</dd>
<dt><samp>VideoBitRate <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set bitrate for the video stream in kbits per second.
</p>
</dd>
<dt><samp>VideoBitRateRange <var>range</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video bitrate range.
</p>
<p>A range must be specified in the form <var>minrate</var>-<var>maxrate</var>, and
specifies the <samp>minrate</samp> and <samp>maxrate</samp> encoding options
expressed in kbits per second.
</p>
</dd>
<dt><samp>VideoBitRateRangeTolerance <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video bitrate tolerance in kbits per second.
</p>
</dd>
<dt><samp>PixelFormat <var>pixel_format</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video pixel format.
</p>
</dd>
<dt><samp>Debug <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video <samp>debug</samp> encoding option.
</p>
</dd>
<dt><samp>Strict <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video <samp>strict</samp> encoding option.
</p>
</dd>
<dt><samp>VideoBufferSize <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set ratecontrol buffer size, expressed in KB.
</p>
</dd>
<dt><samp>VideoFrameRate <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set number of video frames per second.
</p>
</dd>
<dt><samp>VideoSize (<em>encoding,video</em>)</samp></dt>
<dd><p>Set size of the video frame, must be an abbreviation or in the form
<var>W</var>x<var>H</var>. See <a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)the Video size section
in the ffmpeg-utils(1) manual</a>.
</p>
<p>Default value is <code>160x128</code>.
</p>
</dd>
<dt><samp>VideoIntraOnly (<em>encoding,video</em>)</samp></dt>
<dd><p>Transmit only intra frames (useful for low bitrates, but kills frame rate).
</p>
</dd>
<dt><samp>VideoGopSize <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>If non-intra only, an intra frame is transmitted every VideoGopSize
frames. Video synchronization can only begin at an intra frame.
</p>
</dd>
<dt><samp>VideoTag <var>tag</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video tag.
</p>
</dd>
<dt><samp>VideoHighQuality (<em>encoding,video</em>)</samp></dt>
<dt><samp>Video4MotionVector (<em>encoding,video</em>)</samp></dt>
<dt><samp>BitExact (<em>encoding,video</em>)</samp></dt>
<dd><p>Set bitexact encoding flag.
</p>
</dd>
<dt><samp>IdctSimple (<em>encoding,video</em>)</samp></dt>
<dd><p>Set simple IDCT algorithm.
</p>
</dd>
<dt><samp>Qscale <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Enable constant quality encoding, and set video qscale (quantization
scale) value, expressed in <var>n</var> QP units.
</p>
</dd>
<dt><samp>VideoQMin <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>VideoQMax <var>n</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video qmin/qmax.
</p>
</dd>
<dt><samp>VideoQDiff <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video <samp>qdiff</samp> encoding option.
</p>
</dd>
<dt><samp>LumiMask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>DarkMask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set <samp>lumi_mask</samp>/<samp>dark_mask</samp> encoding options.
</p>
</dd>
<dt><samp>AVOptionVideo [<var>codec</var>:]<var>option</var> <var>value</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set generic or private option for video stream.
Private option must be prefixed with codec name or codec must be defined before.
</p>
</dd>
<dt><samp>AVPresetVideo <var>preset</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set preset for video stream.
</p>
<p><var>preset</var> must be the path of a preset file.
</p></dd>
</dl>
<a name="Server-status-stream"></a>
<h4 class="subsection">5.4.1 Server status stream<span class="pull-right"><a class="anchor hidden-xs" href="#Server-status-stream" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Server-status-stream" aria-hidden="true">TOC</a></span></h4>
<p>A server status stream is a special stream which is used to show
statistics about the <code>ffserver</code> operations.
</p>
<p>It must be specified setting the option <samp>Format</samp> to
‘<samp>status</samp>’.
</p>
<a name="Redirect-section"></a>
<h3 class="section">5.5 Redirect section<span class="pull-right"><a class="anchor hidden-xs" href="#Redirect-section" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Redirect-section" aria-hidden="true">TOC</a></span></h3>
<p>A redirect section specifies where to redirect the requested URL to
another page.
</p>
<p>A redirect section must be introduced by the line:
</p><div class="example">
<pre class="example"><Redirect NAME>
</pre></div>
<p>where <var>NAME</var> is the name of the page which should be redirected.
</p>
<p>It only accepts the option <samp>URL</samp>, which specify the redirection
URL.
</p>
<a name="Stream-examples"></a>
<h2 class="chapter">6 Stream examples<span class="pull-right"><a class="anchor hidden-xs" href="#Stream-examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Stream-examples" aria-hidden="true">TOC</a></span></h2>
<ul>
<li> Multipart JPEG
<div class="example">
<pre class="example"><Stream test.mjpg>
Feed feed1.ffm
Format mpjpeg
VideoFrameRate 2
VideoIntraOnly
NoAudio
Strict -1
</Stream>
</pre></div>
</li><li> Single JPEG
<div class="example">
<pre class="example"><Stream test.jpg>
Feed feed1.ffm
Format jpeg
VideoFrameRate 2
VideoIntraOnly
VideoSize 352x240
NoAudio
Strict -1
</Stream>
</pre></div>
</li><li> Flash
<div class="example">
<pre class="example"><Stream test.swf>
Feed feed1.ffm
Format swf
VideoFrameRate 2
VideoIntraOnly
NoAudio
</Stream>
</pre></div>
</li><li> ASF compatible
<div class="example">
<pre class="example"><Stream test.asf>
Feed feed1.ffm
Format asf
VideoFrameRate 15
VideoSize 352x240
VideoBitRate 256
VideoBufferSize 40
VideoGopSize 30
AudioBitRate 64
StartSendOnKey
</Stream>
</pre></div>
</li><li> MP3 audio
<div class="example">
<pre class="example"><Stream test.mp3>
Feed feed1.ffm
Format mp2
AudioCodec mp3
AudioBitRate 64
AudioChannels 1
AudioSampleRate 44100
NoVideo
</Stream>
</pre></div>
</li><li> Ogg Vorbis audio
<div class="example">
<pre class="example"><Stream test.ogg>
Feed feed1.ffm
Metadata title "Stream title"
AudioBitRate 64
AudioChannels 2
AudioSampleRate 44100
NoVideo
</Stream>
</pre></div>
</li><li> Real with audio only at 32 kbits
<div class="example">
<pre class="example"><Stream test.ra>
Feed feed1.ffm
Format rm
AudioBitRate 32
NoVideo
</Stream>
</pre></div>
</li><li> Real with audio and video at 64 kbits
<div class="example">
<pre class="example"><Stream test.rm>
Feed feed1.ffm
Format rm
AudioBitRate 32
VideoBitRate 128
VideoFrameRate 25
VideoGopSize 25
</Stream>
</pre></div>
</li><li> For stream coming from a file: you only need to set the input filename
and optionally a new format.
<div class="example">
<pre class="example"><Stream file.rm>
File "/usr/local/httpd/htdocs/tlive.rm"
NoAudio
</Stream>
</pre></div>
<div class="example">
<pre class="example"><Stream file.asf>
File "/usr/local/httpd/htdocs/test.asf"
NoAudio
Metadata author "Me"
Metadata copyright "Super MegaCorp"
Metadata title "Test stream from disk"
Metadata comment "Test comment"
</Stream>
</pre></div>
</li></ul>
<a name="Syntax"></a>
<h2 class="chapter">7 Syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Syntax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Syntax" aria-hidden="true">TOC</a></span></h2>
<p>This section documents the syntax and formats employed by the FFmpeg
libraries and tools.
</p>
<a name="quoting_005fand_005fescaping"></a><a name="Quoting-and-escaping"></a>
<h3 class="section">7.1 Quoting and escaping<span class="pull-right"><a class="anchor hidden-xs" href="#Quoting-and-escaping" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Quoting-and-escaping" aria-hidden="true">TOC</a></span></h3>
<p>FFmpeg adopts the following quoting and escaping mechanism, unless
explicitly specified. The following rules are applied:
</p>
<ul>
<li> ‘<samp>'</samp>’ and ‘<samp>\</samp>’ are special characters (respectively used for
quoting and escaping). In addition to them, there might be other
special characters depending on the specific syntax where the escaping
and quoting are employed.
</li><li> A special character is escaped by prefixing it with a ‘<samp>\</samp>’.
</li><li> All characters enclosed between ‘<samp>''</samp>’ are included literally in the
parsed string. The quote character ‘<samp>'</samp>’ itself cannot be quoted,
so you may need to close the quote and escape it.
</li><li> Leading and trailing whitespaces, unless escaped or quoted, are
removed from the parsed string.
</li></ul>
<p>Note that you may need to add a second level of escaping when using
the command line or a script, which depends on the syntax of the
adopted shell language.
</p>
<p>The function <code>av_get_token</code> defined in
<samp>libavutil/avstring.h</samp> can be used to parse a token quoted or
escaped according to the rules defined above.
</p>
<p>The tool <samp>tools/ffescape</samp> in the FFmpeg source tree can be used
to automatically quote or escape a string in a script.
</p>
<a name="Examples"></a>
<h4 class="subsection">7.1.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Escape the string <code>Crime d'Amour</code> containing the <code>'</code> special
character:
<div class="example">
<pre class="example">Crime d\'Amour
</pre></div>
</li><li> The string above contains a quote, so the <code>'</code> needs to be escaped
when quoting it:
<div class="example">
<pre class="example">'Crime d'\''Amour'
</pre></div>
</li><li> Include leading or trailing whitespaces using quoting:
<div class="example">
<pre class="example">' this string starts and ends with whitespaces '
</pre></div>
</li><li> Escaping and quoting can be mixed together:
<div class="example">
<pre class="example">' The string '\'string\'' is a string '
</pre></div>
</li><li> To include a literal ‘<samp>\</samp>’ you can use either escaping or quoting:
<div class="example">
<pre class="example">'c:\foo' can be written as c:\\foo
</pre></div>
</li></ul>
<a name="date-syntax"></a><a name="Date"></a>
<h3 class="section">7.2 Date<span class="pull-right"><a class="anchor hidden-xs" href="#Date" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Date" aria-hidden="true">TOC</a></span></h3>
<p>The accepted syntax is:
</p><div class="example">
<pre class="example">[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
now
</pre></div>
<p>If the value is "now" it takes the current time.
</p>
<p>Time is local time unless Z is appended, in which case it is
interpreted as UTC.
If the year-month-day part is not specified it takes the current
year-month-day.
</p>
<a name="time-duration-syntax"></a><a name="Time-duration"></a>
<h3 class="section">7.3 Time duration<span class="pull-right"><a class="anchor hidden-xs" href="#Time-duration" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Time-duration" aria-hidden="true">TOC</a></span></h3>
<p>There are two accepted syntaxes for expressing time duration.
</p>
<div class="example">
<pre class="example">[-][<var>HH</var>:]<var>MM</var>:<var>SS</var>[.<var>m</var>...]
</pre></div>
<p><var>HH</var> expresses the number of hours, <var>MM</var> the number of minutes
for a maximum of 2 digits, and <var>SS</var> the number of seconds for a
maximum of 2 digits. The <var>m</var> at the end expresses decimal value for
<var>SS</var>.
</p>
<p><em>or</em>
</p>
<div class="example">
<pre class="example">[-]<var>S</var>+[.<var>m</var>...]
</pre></div>
<p><var>S</var> expresses the number of seconds, with the optional decimal part
<var>m</var>.
</p>
<p>In both expressions, the optional ‘<samp>-</samp>’ indicates negative duration.
</p>
<a name="Examples-1"></a>
<h4 class="subsection">7.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-1" aria-hidden="true">TOC</a></span></h4>
<p>The following examples are all valid time duration:
</p>
<dl compact="compact">
<dt>‘<samp>55</samp>’</dt>
<dd><p>55 seconds
</p>
</dd>
<dt>‘<samp>12:03:45</samp>’</dt>
<dd><p>12 hours, 03 minutes and 45 seconds
</p>
</dd>
<dt>‘<samp>23.189</samp>’</dt>
<dd><p>23.189 seconds
</p></dd>
</dl>
<a name="video-size-syntax"></a><a name="Video-size"></a>
<h3 class="section">7.4 Video size<span class="pull-right"><a class="anchor hidden-xs" href="#Video-size" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-size" aria-hidden="true">TOC</a></span></h3>
<p>Specify the size of the sourced video, it may be a string of the form
<var>width</var>x<var>height</var>, or the name of a size abbreviation.
</p>
<p>The following abbreviations are recognized:
</p><dl compact="compact">
<dt>‘<samp>ntsc</samp>’</dt>
<dd><p>720x480
</p></dd>
<dt>‘<samp>pal</samp>’</dt>
<dd><p>720x576
</p></dd>
<dt>‘<samp>qntsc</samp>’</dt>
<dd><p>352x240
</p></dd>
<dt>‘<samp>qpal</samp>’</dt>
<dd><p>352x288
</p></dd>
<dt>‘<samp>sntsc</samp>’</dt>
<dd><p>640x480
</p></dd>
<dt>‘<samp>spal</samp>’</dt>
<dd><p>768x576
</p></dd>
<dt>‘<samp>film</samp>’</dt>
<dd><p>352x240
</p></dd>
<dt>‘<samp>ntsc-film</samp>’</dt>
<dd><p>352x240
</p></dd>
<dt>‘<samp>sqcif</samp>’</dt>
<dd><p>128x96
</p></dd>
<dt>‘<samp>qcif</samp>’</dt>
<dd><p>176x144
</p></dd>
<dt>‘<samp>cif</samp>’</dt>
<dd><p>352x288
</p></dd>
<dt>‘<samp>4cif</samp>’</dt>
<dd><p>704x576
</p></dd>
<dt>‘<samp>16cif</samp>’</dt>
<dd><p>1408x1152
</p></dd>
<dt>‘<samp>qqvga</samp>’</dt>
<dd><p>160x120
</p></dd>
<dt>‘<samp>qvga</samp>’</dt>
<dd><p>320x240
</p></dd>
<dt>‘<samp>vga</samp>’</dt>
<dd><p>640x480
</p></dd>
<dt>‘<samp>svga</samp>’</dt>
<dd><p>800x600
</p></dd>
<dt>‘<samp>xga</samp>’</dt>
<dd><p>1024x768
</p></dd>
<dt>‘<samp>uxga</samp>’</dt>
<dd><p>1600x1200
</p></dd>
<dt>‘<samp>qxga</samp>’</dt>
<dd><p>2048x1536
</p></dd>
<dt>‘<samp>sxga</samp>’</dt>
<dd><p>1280x1024
</p></dd>
<dt>‘<samp>qsxga</samp>’</dt>
<dd><p>2560x2048
</p></dd>
<dt>‘<samp>hsxga</samp>’</dt>
<dd><p>5120x4096
</p></dd>
<dt>‘<samp>wvga</samp>’</dt>
<dd><p>852x480
</p></dd>
<dt>‘<samp>wxga</samp>’</dt>
<dd><p>1366x768
</p></dd>
<dt>‘<samp>wsxga</samp>’</dt>
<dd><p>1600x1024
</p></dd>
<dt>‘<samp>wuxga</samp>’</dt>
<dd><p>1920x1200
</p></dd>
<dt>‘<samp>woxga</samp>’</dt>
<dd><p>2560x1600
</p></dd>
<dt>‘<samp>wqsxga</samp>’</dt>
<dd><p>3200x2048
</p></dd>
<dt>‘<samp>wquxga</samp>’</dt>
<dd><p>3840x2400
</p></dd>
<dt>‘<samp>whsxga</samp>’</dt>
<dd><p>6400x4096
</p></dd>
<dt>‘<samp>whuxga</samp>’</dt>
<dd><p>7680x4800
</p></dd>
<dt>‘<samp>cga</samp>’</dt>
<dd><p>320x200
</p></dd>
<dt>‘<samp>ega</samp>’</dt>
<dd><p>640x350
</p></dd>
<dt>‘<samp>hd480</samp>’</dt>
<dd><p>852x480
</p></dd>
<dt>‘<samp>hd720</samp>’</dt>
<dd><p>1280x720
</p></dd>
<dt>‘<samp>hd1080</samp>’</dt>
<dd><p>1920x1080
</p></dd>
<dt>‘<samp>2k</samp>’</dt>
<dd><p>2048x1080
</p></dd>
<dt>‘<samp>2kflat</samp>’</dt>
<dd><p>1998x1080
</p></dd>
<dt>‘<samp>2kscope</samp>’</dt>
<dd><p>2048x858
</p></dd>
<dt>‘<samp>4k</samp>’</dt>
<dd><p>4096x2160
</p></dd>
<dt>‘<samp>4kflat</samp>’</dt>
<dd><p>3996x2160
</p></dd>
<dt>‘<samp>4kscope</samp>’</dt>
<dd><p>4096x1716
</p></dd>
<dt>‘<samp>nhd</samp>’</dt>
<dd><p>640x360
</p></dd>
<dt>‘<samp>hqvga</samp>’</dt>
<dd><p>240x160
</p></dd>
<dt>‘<samp>wqvga</samp>’</dt>
<dd><p>400x240
</p></dd>
<dt>‘<samp>fwqvga</samp>’</dt>
<dd><p>432x240
</p></dd>
<dt>‘<samp>hvga</samp>’</dt>
<dd><p>480x320
</p></dd>
<dt>‘<samp>qhd</samp>’</dt>
<dd><p>960x540
</p></dd>
<dt>‘<samp>2kdci</samp>’</dt>
<dd><p>2048x1080
</p></dd>
<dt>‘<samp>4kdci</samp>’</dt>
<dd><p>4096x2160
</p></dd>
<dt>‘<samp>uhd2160</samp>’</dt>
<dd><p>3840x2160
</p></dd>
<dt>‘<samp>uhd4320</samp>’</dt>
<dd><p>7680x4320
</p></dd>
</dl>
<a name="video-rate-syntax"></a><a name="Video-rate"></a>
<h3 class="section">7.5 Video rate<span class="pull-right"><a class="anchor hidden-xs" href="#Video-rate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-rate" aria-hidden="true">TOC</a></span></h3>
<p>Specify the frame rate of a video, expressed as the number of frames
generated per second. It has to be a string in the format
<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a float
number or a valid video frame rate abbreviation.
</p>
<p>The following abbreviations are recognized:
</p><dl compact="compact">
<dt>‘<samp>ntsc</samp>’</dt>
<dd><p>30000/1001
</p></dd>
<dt>‘<samp>pal</samp>’</dt>
<dd><p>25/1
</p></dd>
<dt>‘<samp>qntsc</samp>’</dt>
<dd><p>30000/1001
</p></dd>
<dt>‘<samp>qpal</samp>’</dt>
<dd><p>25/1
</p></dd>
<dt>‘<samp>sntsc</samp>’</dt>
<dd><p>30000/1001
</p></dd>
<dt>‘<samp>spal</samp>’</dt>
<dd><p>25/1
</p></dd>
<dt>‘<samp>film</samp>’</dt>
<dd><p>24/1
</p></dd>
<dt>‘<samp>ntsc-film</samp>’</dt>
<dd><p>24000/1001
</p></dd>
</dl>
<a name="ratio-syntax"></a><a name="Ratio"></a>
<h3 class="section">7.6 Ratio<span class="pull-right"><a class="anchor hidden-xs" href="#Ratio" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Ratio" aria-hidden="true">TOC</a></span></h3>
<p>A ratio can be expressed as an expression, or in the form
<var>numerator</var>:<var>denominator</var>.
</p>
<p>Note that a ratio with infinite (1/0) or negative value is
considered valid, so you should check on the returned value if you
want to exclude those values.
</p>
<p>The undefined value can be expressed using the "0:0" string.
</p>
<a name="color-syntax"></a><a name="Color"></a>
<h3 class="section">7.7 Color<span class="pull-right"><a class="anchor hidden-xs" href="#Color" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Color" aria-hidden="true">TOC</a></span></h3>
<p>It can be the name of a color as defined below (case insensitive match) or a
<code>[0x|#]RRGGBB[AA]</code> sequence, possibly followed by @ and a string
representing the alpha component.
</p>
<p>The alpha component may be a string composed by "0x" followed by an
hexadecimal number or a decimal number between 0.0 and 1.0, which
represents the opacity value (‘<samp>0x00</samp>’ or ‘<samp>0.0</samp>’ means completely
transparent, ‘<samp>0xff</samp>’ or ‘<samp>1.0</samp>’ completely opaque). If the alpha
component is not specified then ‘<samp>0xff</samp>’ is assumed.
</p>
<p>The string ‘<samp>random</samp>’ will result in a random color.
</p>
<p>The following names of colors are recognized:
</p><dl compact="compact">
<dt>‘<samp>AliceBlue</samp>’</dt>
<dd><p>0xF0F8FF
</p></dd>
<dt>‘<samp>AntiqueWhite</samp>’</dt>
<dd><p>0xFAEBD7
</p></dd>
<dt>‘<samp>Aqua</samp>’</dt>
<dd><p>0x00FFFF
</p></dd>
<dt>‘<samp>Aquamarine</samp>’</dt>
<dd><p>0x7FFFD4
</p></dd>
<dt>‘<samp>Azure</samp>’</dt>
<dd><p>0xF0FFFF
</p></dd>
<dt>‘<samp>Beige</samp>’</dt>
<dd><p>0xF5F5DC
</p></dd>
<dt>‘<samp>Bisque</samp>’</dt>
<dd><p>0xFFE4C4
</p></dd>
<dt>‘<samp>Black</samp>’</dt>
<dd><p>0x000000
</p></dd>
<dt>‘<samp>BlanchedAlmond</samp>’</dt>
<dd><p>0xFFEBCD
</p></dd>
<dt>‘<samp>Blue</samp>’</dt>
<dd><p>0x0000FF
</p></dd>
<dt>‘<samp>BlueViolet</samp>’</dt>
<dd><p>0x8A2BE2
</p></dd>
<dt>‘<samp>Brown</samp>’</dt>
<dd><p>0xA52A2A
</p></dd>
<dt>‘<samp>BurlyWood</samp>’</dt>
<dd><p>0xDEB887
</p></dd>
<dt>‘<samp>CadetBlue</samp>’</dt>
<dd><p>0x5F9EA0
</p></dd>
<dt>‘<samp>Chartreuse</samp>’</dt>
<dd><p>0x7FFF00
</p></dd>
<dt>‘<samp>Chocolate</samp>’</dt>
<dd><p>0xD2691E
</p></dd>
<dt>‘<samp>Coral</samp>’</dt>
<dd><p>0xFF7F50
</p></dd>
<dt>‘<samp>CornflowerBlue</samp>’</dt>
<dd><p>0x6495ED
</p></dd>
<dt>‘<samp>Cornsilk</samp>’</dt>
<dd><p>0xFFF8DC
</p></dd>
<dt>‘<samp>Crimson</samp>’</dt>
<dd><p>0xDC143C
</p></dd>
<dt>‘<samp>Cyan</samp>’</dt>
<dd><p>0x00FFFF
</p></dd>
<dt>‘<samp>DarkBlue</samp>’</dt>
<dd><p>0x00008B
</p></dd>
<dt>‘<samp>DarkCyan</samp>’</dt>
<dd><p>0x008B8B
</p></dd>
<dt>‘<samp>DarkGoldenRod</samp>’</dt>
<dd><p>0xB8860B
</p></dd>
<dt>‘<samp>DarkGray</samp>’</dt>
<dd><p>0xA9A9A9
</p></dd>
<dt>‘<samp>DarkGreen</samp>’</dt>
<dd><p>0x006400
</p></dd>
<dt>‘<samp>DarkKhaki</samp>’</dt>
<dd><p>0xBDB76B
</p></dd>
<dt>‘<samp>DarkMagenta</samp>’</dt>
<dd><p>0x8B008B
</p></dd>
<dt>‘<samp>DarkOliveGreen</samp>’</dt>
<dd><p>0x556B2F
</p></dd>
<dt>‘<samp>Darkorange</samp>’</dt>
<dd><p>0xFF8C00
</p></dd>
<dt>‘<samp>DarkOrchid</samp>’</dt>
<dd><p>0x9932CC
</p></dd>
<dt>‘<samp>DarkRed</samp>’</dt>
<dd><p>0x8B0000
</p></dd>
<dt>‘<samp>DarkSalmon</samp>’</dt>
<dd><p>0xE9967A
</p></dd>
<dt>‘<samp>DarkSeaGreen</samp>’</dt>
<dd><p>0x8FBC8F
</p></dd>
<dt>‘<samp>DarkSlateBlue</samp>’</dt>
<dd><p>0x483D8B
</p></dd>
<dt>‘<samp>DarkSlateGray</samp>’</dt>
<dd><p>0x2F4F4F
</p></dd>
<dt>‘<samp>DarkTurquoise</samp>’</dt>
<dd><p>0x00CED1
</p></dd>
<dt>‘<samp>DarkViolet</samp>’</dt>
<dd><p>0x9400D3
</p></dd>
<dt>‘<samp>DeepPink</samp>’</dt>
<dd><p>0xFF1493
</p></dd>
<dt>‘<samp>DeepSkyBlue</samp>’</dt>
<dd><p>0x00BFFF
</p></dd>
<dt>‘<samp>DimGray</samp>’</dt>
<dd><p>0x696969
</p></dd>
<dt>‘<samp>DodgerBlue</samp>’</dt>
<dd><p>0x1E90FF
</p></dd>
<dt>‘<samp>FireBrick</samp>’</dt>
<dd><p>0xB22222
</p></dd>
<dt>‘<samp>FloralWhite</samp>’</dt>
<dd><p>0xFFFAF0
</p></dd>
<dt>‘<samp>ForestGreen</samp>’</dt>
<dd><p>0x228B22
</p></dd>
<dt>‘<samp>Fuchsia</samp>’</dt>
<dd><p>0xFF00FF
</p></dd>
<dt>‘<samp>Gainsboro</samp>’</dt>
<dd><p>0xDCDCDC
</p></dd>
<dt>‘<samp>GhostWhite</samp>’</dt>
<dd><p>0xF8F8FF
</p></dd>
<dt>‘<samp>Gold</samp>’</dt>
<dd><p>0xFFD700
</p></dd>
<dt>‘<samp>GoldenRod</samp>’</dt>
<dd><p>0xDAA520
</p></dd>
<dt>‘<samp>Gray</samp>’</dt>
<dd><p>0x808080
</p></dd>
<dt>‘<samp>Green</samp>’</dt>
<dd><p>0x008000
</p></dd>
<dt>‘<samp>GreenYellow</samp>’</dt>
<dd><p>0xADFF2F
</p></dd>
<dt>‘<samp>HoneyDew</samp>’</dt>
<dd><p>0xF0FFF0
</p></dd>
<dt>‘<samp>HotPink</samp>’</dt>
<dd><p>0xFF69B4
</p></dd>
<dt>‘<samp>IndianRed</samp>’</dt>
<dd><p>0xCD5C5C
</p></dd>
<dt>‘<samp>Indigo</samp>’</dt>
<dd><p>0x4B0082
</p></dd>
<dt>‘<samp>Ivory</samp>’</dt>
<dd><p>0xFFFFF0
</p></dd>
<dt>‘<samp>Khaki</samp>’</dt>
<dd><p>0xF0E68C
</p></dd>
<dt>‘<samp>Lavender</samp>’</dt>
<dd><p>0xE6E6FA
</p></dd>
<dt>‘<samp>LavenderBlush</samp>’</dt>
<dd><p>0xFFF0F5
</p></dd>
<dt>‘<samp>LawnGreen</samp>’</dt>
<dd><p>0x7CFC00
</p></dd>
<dt>‘<samp>LemonChiffon</samp>’</dt>
<dd><p>0xFFFACD
</p></dd>
<dt>‘<samp>LightBlue</samp>’</dt>
<dd><p>0xADD8E6
</p></dd>
<dt>‘<samp>LightCoral</samp>’</dt>
<dd><p>0xF08080
</p></dd>
<dt>‘<samp>LightCyan</samp>’</dt>
<dd><p>0xE0FFFF
</p></dd>
<dt>‘<samp>LightGoldenRodYellow</samp>’</dt>
<dd><p>0xFAFAD2
</p></dd>
<dt>‘<samp>LightGreen</samp>’</dt>
<dd><p>0x90EE90
</p></dd>
<dt>‘<samp>LightGrey</samp>’</dt>
<dd><p>0xD3D3D3
</p></dd>
<dt>‘<samp>LightPink</samp>’</dt>
<dd><p>0xFFB6C1
</p></dd>
<dt>‘<samp>LightSalmon</samp>’</dt>
<dd><p>0xFFA07A
</p></dd>
<dt>‘<samp>LightSeaGreen</samp>’</dt>
<dd><p>0x20B2AA
</p></dd>
<dt>‘<samp>LightSkyBlue</samp>’</dt>
<dd><p>0x87CEFA
</p></dd>
<dt>‘<samp>LightSlateGray</samp>’</dt>
<dd><p>0x778899
</p></dd>
<dt>‘<samp>LightSteelBlue</samp>’</dt>
<dd><p>0xB0C4DE
</p></dd>
<dt>‘<samp>LightYellow</samp>’</dt>
<dd><p>0xFFFFE0
</p></dd>
<dt>‘<samp>Lime</samp>’</dt>
<dd><p>0x00FF00
</p></dd>
<dt>‘<samp>LimeGreen</samp>’</dt>
<dd><p>0x32CD32
</p></dd>
<dt>‘<samp>Linen</samp>’</dt>
<dd><p>0xFAF0E6
</p></dd>
<dt>‘<samp>Magenta</samp>’</dt>
<dd><p>0xFF00FF
</p></dd>
<dt>‘<samp>Maroon</samp>’</dt>
<dd><p>0x800000
</p></dd>
<dt>‘<samp>MediumAquaMarine</samp>’</dt>
<dd><p>0x66CDAA
</p></dd>
<dt>‘<samp>MediumBlue</samp>’</dt>
<dd><p>0x0000CD
</p></dd>
<dt>‘<samp>MediumOrchid</samp>’</dt>
<dd><p>0xBA55D3
</p></dd>
<dt>‘<samp>MediumPurple</samp>’</dt>
<dd><p>0x9370D8
</p></dd>
<dt>‘<samp>MediumSeaGreen</samp>’</dt>
<dd><p>0x3CB371
</p></dd>
<dt>‘<samp>MediumSlateBlue</samp>’</dt>
<dd><p>0x7B68EE
</p></dd>
<dt>‘<samp>MediumSpringGreen</samp>’</dt>
<dd><p>0x00FA9A
</p></dd>
<dt>‘<samp>MediumTurquoise</samp>’</dt>
<dd><p>0x48D1CC
</p></dd>
<dt>‘<samp>MediumVioletRed</samp>’</dt>
<dd><p>0xC71585
</p></dd>
<dt>‘<samp>MidnightBlue</samp>’</dt>
<dd><p>0x191970
</p></dd>
<dt>‘<samp>MintCream</samp>’</dt>
<dd><p>0xF5FFFA
</p></dd>
<dt>‘<samp>MistyRose</samp>’</dt>
<dd><p>0xFFE4E1
</p></dd>
<dt>‘<samp>Moccasin</samp>’</dt>
<dd><p>0xFFE4B5
</p></dd>
<dt>‘<samp>NavajoWhite</samp>’</dt>
<dd><p>0xFFDEAD
</p></dd>
<dt>‘<samp>Navy</samp>’</dt>
<dd><p>0x000080
</p></dd>
<dt>‘<samp>OldLace</samp>’</dt>
<dd><p>0xFDF5E6
</p></dd>
<dt>‘<samp>Olive</samp>’</dt>
<dd><p>0x808000
</p></dd>
<dt>‘<samp>OliveDrab</samp>’</dt>
<dd><p>0x6B8E23
</p></dd>
<dt>‘<samp>Orange</samp>’</dt>
<dd><p>0xFFA500
</p></dd>
<dt>‘<samp>OrangeRed</samp>’</dt>
<dd><p>0xFF4500
</p></dd>
<dt>‘<samp>Orchid</samp>’</dt>
<dd><p>0xDA70D6
</p></dd>
<dt>‘<samp>PaleGoldenRod</samp>’</dt>
<dd><p>0xEEE8AA
</p></dd>
<dt>‘<samp>PaleGreen</samp>’</dt>
<dd><p>0x98FB98
</p></dd>
<dt>‘<samp>PaleTurquoise</samp>’</dt>
<dd><p>0xAFEEEE
</p></dd>
<dt>‘<samp>PaleVioletRed</samp>’</dt>
<dd><p>0xD87093
</p></dd>
<dt>‘<samp>PapayaWhip</samp>’</dt>
<dd><p>0xFFEFD5
</p></dd>
<dt>‘<samp>PeachPuff</samp>’</dt>
<dd><p>0xFFDAB9
</p></dd>
<dt>‘<samp>Peru</samp>’</dt>
<dd><p>0xCD853F
</p></dd>
<dt>‘<samp>Pink</samp>’</dt>
<dd><p>0xFFC0CB
</p></dd>
<dt>‘<samp>Plum</samp>’</dt>
<dd><p>0xDDA0DD
</p></dd>
<dt>‘<samp>PowderBlue</samp>’</dt>
<dd><p>0xB0E0E6
</p></dd>
<dt>‘<samp>Purple</samp>’</dt>
<dd><p>0x800080
</p></dd>
<dt>‘<samp>Red</samp>’</dt>
<dd><p>0xFF0000
</p></dd>
<dt>‘<samp>RosyBrown</samp>’</dt>
<dd><p>0xBC8F8F
</p></dd>
<dt>‘<samp>RoyalBlue</samp>’</dt>
<dd><p>0x4169E1
</p></dd>
<dt>‘<samp>SaddleBrown</samp>’</dt>
<dd><p>0x8B4513
</p></dd>
<dt>‘<samp>Salmon</samp>’</dt>
<dd><p>0xFA8072
</p></dd>
<dt>‘<samp>SandyBrown</samp>’</dt>
<dd><p>0xF4A460
</p></dd>
<dt>‘<samp>SeaGreen</samp>’</dt>
<dd><p>0x2E8B57
</p></dd>
<dt>‘<samp>SeaShell</samp>’</dt>
<dd><p>0xFFF5EE
</p></dd>
<dt>‘<samp>Sienna</samp>’</dt>
<dd><p>0xA0522D
</p></dd>
<dt>‘<samp>Silver</samp>’</dt>
<dd><p>0xC0C0C0
</p></dd>
<dt>‘<samp>SkyBlue</samp>’</dt>
<dd><p>0x87CEEB
</p></dd>
<dt>‘<samp>SlateBlue</samp>’</dt>
<dd><p>0x6A5ACD
</p></dd>
<dt>‘<samp>SlateGray</samp>’</dt>
<dd><p>0x708090
</p></dd>
<dt>‘<samp>Snow</samp>’</dt>
<dd><p>0xFFFAFA
</p></dd>
<dt>‘<samp>SpringGreen</samp>’</dt>
<dd><p>0x00FF7F
</p></dd>
<dt>‘<samp>SteelBlue</samp>’</dt>
<dd><p>0x4682B4
</p></dd>
<dt>‘<samp>Tan</samp>’</dt>
<dd><p>0xD2B48C
</p></dd>
<dt>‘<samp>Teal</samp>’</dt>
<dd><p>0x008080
</p></dd>
<dt>‘<samp>Thistle</samp>’</dt>
<dd><p>0xD8BFD8
</p></dd>
<dt>‘<samp>Tomato</samp>’</dt>
<dd><p>0xFF6347
</p></dd>
<dt>‘<samp>Turquoise</samp>’</dt>
<dd><p>0x40E0D0
</p></dd>
<dt>‘<samp>Violet</samp>’</dt>
<dd><p>0xEE82EE
</p></dd>
<dt>‘<samp>Wheat</samp>’</dt>
<dd><p>0xF5DEB3
</p></dd>
<dt>‘<samp>White</samp>’</dt>
<dd><p>0xFFFFFF
</p></dd>
<dt>‘<samp>WhiteSmoke</samp>’</dt>
<dd><p>0xF5F5F5
</p></dd>
<dt>‘<samp>Yellow</samp>’</dt>
<dd><p>0xFFFF00
</p></dd>
<dt>‘<samp>YellowGreen</samp>’</dt>
<dd><p>0x9ACD32
</p></dd>
</dl>
<a name="channel-layout-syntax"></a><a name="Channel-Layout"></a>
<h3 class="section">7.8 Channel Layout<span class="pull-right"><a class="anchor hidden-xs" href="#Channel-Layout" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Channel-Layout" aria-hidden="true">TOC</a></span></h3>
<p>A channel layout specifies the spatial disposition of the channels in
a multi-channel audio stream. To specify a channel layout, FFmpeg
makes use of a special syntax.
</p>
<p>Individual channels are identified by an id, as given by the table
below:
</p><dl compact="compact">
<dt>‘<samp>FL</samp>’</dt>
<dd><p>front left
</p></dd>
<dt>‘<samp>FR</samp>’</dt>
<dd><p>front right
</p></dd>
<dt>‘<samp>FC</samp>’</dt>
<dd><p>front center
</p></dd>
<dt>‘<samp>LFE</samp>’</dt>
<dd><p>low frequency
</p></dd>
<dt>‘<samp>BL</samp>’</dt>
<dd><p>back left
</p></dd>
<dt>‘<samp>BR</samp>’</dt>
<dd><p>back right
</p></dd>
<dt>‘<samp>FLC</samp>’</dt>
<dd><p>front left-of-center
</p></dd>
<dt>‘<samp>FRC</samp>’</dt>
<dd><p>front right-of-center
</p></dd>
<dt>‘<samp>BC</samp>’</dt>
<dd><p>back center
</p></dd>
<dt>‘<samp>SL</samp>’</dt>
<dd><p>side left
</p></dd>
<dt>‘<samp>SR</samp>’</dt>
<dd><p>side right
</p></dd>
<dt>‘<samp>TC</samp>’</dt>
<dd><p>top center
</p></dd>
<dt>‘<samp>TFL</samp>’</dt>
<dd><p>top front left
</p></dd>
<dt>‘<samp>TFC</samp>’</dt>
<dd><p>top front center
</p></dd>
<dt>‘<samp>TFR</samp>’</dt>
<dd><p>top front right
</p></dd>
<dt>‘<samp>TBL</samp>’</dt>
<dd><p>top back left
</p></dd>
<dt>‘<samp>TBC</samp>’</dt>
<dd><p>top back center
</p></dd>
<dt>‘<samp>TBR</samp>’</dt>
<dd><p>top back right
</p></dd>
<dt>‘<samp>DL</samp>’</dt>
<dd><p>downmix left
</p></dd>
<dt>‘<samp>DR</samp>’</dt>
<dd><p>downmix right
</p></dd>
<dt>‘<samp>WL</samp>’</dt>
<dd><p>wide left
</p></dd>
<dt>‘<samp>WR</samp>’</dt>
<dd><p>wide right
</p></dd>
<dt>‘<samp>SDL</samp>’</dt>
<dd><p>surround direct left
</p></dd>
<dt>‘<samp>SDR</samp>’</dt>
<dd><p>surround direct right
</p></dd>
<dt>‘<samp>LFE2</samp>’</dt>
<dd><p>low frequency 2
</p></dd>
</dl>
<p>Standard channel layout compositions can be specified by using the
following identifiers:
</p><dl compact="compact">
<dt>‘<samp>mono</samp>’</dt>
<dd><p>FC
</p></dd>
<dt>‘<samp>stereo</samp>’</dt>
<dd><p>FL+FR
</p></dd>
<dt>‘<samp>2.1</samp>’</dt>
<dd><p>FL+FR+LFE
</p></dd>
<dt>‘<samp>3.0</samp>’</dt>
<dd><p>FL+FR+FC
</p></dd>
<dt>‘<samp>3.0(back)</samp>’</dt>
<dd><p>FL+FR+BC
</p></dd>
<dt>‘<samp>4.0</samp>’</dt>
<dd><p>FL+FR+FC+BC
</p></dd>
<dt>‘<samp>quad</samp>’</dt>
<dd><p>FL+FR+BL+BR
</p></dd>
<dt>‘<samp>quad(side)</samp>’</dt>
<dd><p>FL+FR+SL+SR
</p></dd>
<dt>‘<samp>3.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE
</p></dd>
<dt>‘<samp>5.0</samp>’</dt>
<dd><p>FL+FR+FC+BL+BR
</p></dd>
<dt>‘<samp>5.0(side)</samp>’</dt>
<dd><p>FL+FR+FC+SL+SR
</p></dd>
<dt>‘<samp>4.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BC
</p></dd>
<dt>‘<samp>5.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BL+BR
</p></dd>
<dt>‘<samp>5.1(side)</samp>’</dt>
<dd><p>FL+FR+FC+LFE+SL+SR
</p></dd>
<dt>‘<samp>6.0</samp>’</dt>
<dd><p>FL+FR+FC+BC+SL+SR
</p></dd>
<dt>‘<samp>6.0(front)</samp>’</dt>
<dd><p>FL+FR+FLC+FRC+SL+SR
</p></dd>
<dt>‘<samp>hexagonal</samp>’</dt>
<dd><p>FL+FR+FC+BL+BR+BC
</p></dd>
<dt>‘<samp>6.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BC+SL+SR
</p></dd>
<dt>‘<samp>6.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BL+BR+BC
</p></dd>
<dt>‘<samp>6.1(front)</samp>’</dt>
<dd><p>FL+FR+LFE+FLC+FRC+SL+SR
</p></dd>
<dt>‘<samp>7.0</samp>’</dt>
<dd><p>FL+FR+FC+BL+BR+SL+SR
</p></dd>
<dt>‘<samp>7.0(front)</samp>’</dt>
<dd><p>FL+FR+FC+FLC+FRC+SL+SR
</p></dd>
<dt>‘<samp>7.1</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BL+BR+SL+SR
</p></dd>
<dt>‘<samp>7.1(wide)</samp>’</dt>
<dd><p>FL+FR+FC+LFE+BL+BR+FLC+FRC
</p></dd>
<dt>‘<samp>7.1(wide-side)</samp>’</dt>
<dd><p>FL+FR+FC+LFE+FLC+FRC+SL+SR
</p></dd>
<dt>‘<samp>octagonal</samp>’</dt>
<dd><p>FL+FR+FC+BL+BR+BC+SL+SR
</p></dd>
<dt>‘<samp>downmix</samp>’</dt>
<dd><p>DL+DR
</p></dd>
</dl>
<p>A custom channel layout can be specified as a sequence of terms, separated by
’+’ or ’|’. Each term can be:
</p><ul>
<li> the name of a standard channel layout (e.g. ‘<samp>mono</samp>’,
‘<samp>stereo</samp>’, ‘<samp>4.0</samp>’, ‘<samp>quad</samp>’, ‘<samp>5.0</samp>’, etc.)
</li><li> the name of a single channel (e.g. ‘<samp>FL</samp>’, ‘<samp>FR</samp>’, ‘<samp>FC</samp>’, ‘<samp>LFE</samp>’, etc.)
</li><li> a number of channels, in decimal, optionally followed by ’c’, yielding
the default channel layout for that number of channels (see the
function <code>av_get_default_channel_layout</code>)
</li><li> a channel layout mask, in hexadecimal starting with "0x" (see the
<code>AV_CH_*</code> macros in <samp>libavutil/channel_layout.h</samp>.
</li></ul>
<p>Starting from libavutil version 53 the trailing character "c" to
specify a number of channels will be required, while a channel layout
mask could also be specified as a decimal number (if and only if not
followed by "c").
</p>
<p>See also the function <code>av_get_channel_layout</code> defined in
<samp>libavutil/channel_layout.h</samp>.
</p>
<a name="Expression-Evaluation"></a>
<h2 class="chapter">8 Expression Evaluation<span class="pull-right"><a class="anchor hidden-xs" href="#Expression-Evaluation" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Expression-Evaluation" aria-hidden="true">TOC</a></span></h2>
<p>When evaluating an arithmetic expression, FFmpeg uses an internal
formula evaluator, implemented through the <samp>libavutil/eval.h</samp>
interface.
</p>
<p>An expression may contain unary, binary operators, constants, and
functions.
</p>
<p>Two expressions <var>expr1</var> and <var>expr2</var> can be combined to form
another expression "<var>expr1</var>;<var>expr2</var>".
<var>expr1</var> and <var>expr2</var> are evaluated in turn, and the new
expression evaluates to the value of <var>expr2</var>.
</p>
<p>The following binary operators are available: <code>+</code>, <code>-</code>,
<code>*</code>, <code>/</code>, <code>^</code>.
</p>
<p>The following unary operators are available: <code>+</code>, <code>-</code>.
</p>
<p>The following functions are available:
</p><dl compact="compact">
<dt><samp>abs(x)</samp></dt>
<dd><p>Compute absolute value of <var>x</var>.
</p>
</dd>
<dt><samp>acos(x)</samp></dt>
<dd><p>Compute arccosine of <var>x</var>.
</p>
</dd>
<dt><samp>asin(x)</samp></dt>
<dd><p>Compute arcsine of <var>x</var>.
</p>
</dd>
<dt><samp>atan(x)</samp></dt>
<dd><p>Compute arctangent of <var>x</var>.
</p>
</dd>
<dt><samp>between(x, min, max)</samp></dt>
<dd><p>Return 1 if <var>x</var> is greater than or equal to <var>min</var> and lesser than or
equal to <var>max</var>, 0 otherwise.
</p>
</dd>
<dt><samp>bitand(x, y)</samp></dt>
<dt><samp>bitor(x, y)</samp></dt>
<dd><p>Compute bitwise and/or operation on <var>x</var> and <var>y</var>.
</p>
<p>The results of the evaluation of <var>x</var> and <var>y</var> are converted to
integers before executing the bitwise operation.
</p>
<p>Note that both the conversion to integer and the conversion back to
floating point can lose precision. Beware of unexpected results for
large numbers (usually 2^53 and larger).
</p>
</dd>
<dt><samp>ceil(expr)</samp></dt>
<dd><p>Round the value of expression <var>expr</var> upwards to the nearest
integer. For example, "ceil(1.5)" is "2.0".
</p>
</dd>
<dt><samp>clip(x, min, max)</samp></dt>
<dd><p>Return the value of <var>x</var> clipped between <var>min</var> and <var>max</var>.
</p>
</dd>
<dt><samp>cos(x)</samp></dt>
<dd><p>Compute cosine of <var>x</var>.
</p>
</dd>
<dt><samp>cosh(x)</samp></dt>
<dd><p>Compute hyperbolic cosine of <var>x</var>.
</p>
</dd>
<dt><samp>eq(x, y)</samp></dt>
<dd><p>Return 1 if <var>x</var> and <var>y</var> are equivalent, 0 otherwise.
</p>
</dd>
<dt><samp>exp(x)</samp></dt>
<dd><p>Compute exponential of <var>x</var> (with base <code>e</code>, the Euler’s number).
</p>
</dd>
<dt><samp>floor(expr)</samp></dt>
<dd><p>Round the value of expression <var>expr</var> downwards to the nearest
integer. For example, "floor(-1.5)" is "-2.0".
</p>
</dd>
<dt><samp>gauss(x)</samp></dt>
<dd><p>Compute Gauss function of <var>x</var>, corresponding to
<code>exp(-x*x/2) / sqrt(2*PI)</code>.
</p>
</dd>
<dt><samp>gcd(x, y)</samp></dt>
<dd><p>Return the greatest common divisor of <var>x</var> and <var>y</var>. If both <var>x</var> and
<var>y</var> are 0 or either or both are less than zero then behavior is undefined.
</p>
</dd>
<dt><samp>gt(x, y)</samp></dt>
<dd><p>Return 1 if <var>x</var> is greater than <var>y</var>, 0 otherwise.
</p>
</dd>
<dt><samp>gte(x, y)</samp></dt>
<dd><p>Return 1 if <var>x</var> is greater than or equal to <var>y</var>, 0 otherwise.
</p>
</dd>
<dt><samp>hypot(x, y)</samp></dt>
<dd><p>This function is similar to the C function with the same name; it returns
"sqrt(<var>x</var>*<var>x</var> + <var>y</var>*<var>y</var>)", the length of the hypotenuse of a
right triangle with sides of length <var>x</var> and <var>y</var>, or the distance of the
point (<var>x</var>, <var>y</var>) from the origin.
</p>
</dd>
<dt><samp>if(x, y)</samp></dt>
<dd><p>Evaluate <var>x</var>, and if the result is non-zero return the result of
the evaluation of <var>y</var>, return 0 otherwise.
</p>
</dd>
<dt><samp>if(x, y, z)</samp></dt>
<dd><p>Evaluate <var>x</var>, and if the result is non-zero return the evaluation
result of <var>y</var>, otherwise the evaluation result of <var>z</var>.
</p>
</dd>
<dt><samp>ifnot(x, y)</samp></dt>
<dd><p>Evaluate <var>x</var>, and if the result is zero return the result of the
evaluation of <var>y</var>, return 0 otherwise.
</p>
</dd>
<dt><samp>ifnot(x, y, z)</samp></dt>
<dd><p>Evaluate <var>x</var>, and if the result is zero return the evaluation
result of <var>y</var>, otherwise the evaluation result of <var>z</var>.
</p>
</dd>
<dt><samp>isinf(x)</samp></dt>
<dd><p>Return 1.0 if <var>x</var> is +/-INFINITY, 0.0 otherwise.
</p>
</dd>
<dt><samp>isnan(x)</samp></dt>
<dd><p>Return 1.0 if <var>x</var> is NAN, 0.0 otherwise.
</p>
</dd>
<dt><samp>ld(var)</samp></dt>
<dd><p>Load the value of the internal variable with number
<var>var</var>, which was previously stored with st(<var>var</var>, <var>expr</var>).
The function returns the loaded value.
</p>
</dd>
<dt><samp>log(x)</samp></dt>
<dd><p>Compute natural logarithm of <var>x</var>.
</p>
</dd>
<dt><samp>lt(x, y)</samp></dt>
<dd><p>Return 1 if <var>x</var> is lesser than <var>y</var>, 0 otherwise.
</p>
</dd>
<dt><samp>lte(x, y)</samp></dt>
<dd><p>Return 1 if <var>x</var> is lesser than or equal to <var>y</var>, 0 otherwise.
</p>
</dd>
<dt><samp>max(x, y)</samp></dt>
<dd><p>Return the maximum between <var>x</var> and <var>y</var>.
</p>
</dd>
<dt><samp>min(x, y)</samp></dt>
<dd><p>Return the maximum between <var>x</var> and <var>y</var>.
</p>
</dd>
<dt><samp>mod(x, y)</samp></dt>
<dd><p>Compute the remainder of division of <var>x</var> by <var>y</var>.
</p>
</dd>
<dt><samp>not(expr)</samp></dt>
<dd><p>Return 1.0 if <var>expr</var> is zero, 0.0 otherwise.
</p>
</dd>
<dt><samp>pow(x, y)</samp></dt>
<dd><p>Compute the power of <var>x</var> elevated <var>y</var>, it is equivalent to
"(<var>x</var>)^(<var>y</var>)".
</p>
</dd>
<dt><samp>print(t)</samp></dt>
<dt><samp>print(t, l)</samp></dt>
<dd><p>Print the value of expression <var>t</var> with loglevel <var>l</var>. If
<var>l</var> is not specified then a default log level is used.
Returns the value of the expression printed.
</p>
<p>Prints t with loglevel l
</p>
</dd>
<dt><samp>random(x)</samp></dt>
<dd><p>Return a pseudo random value between 0.0 and 1.0. <var>x</var> is the index of the
internal variable which will be used to save the seed/state.
</p>
</dd>
<dt><samp>root(expr, max)</samp></dt>
<dd><p>Find an input value for which the function represented by <var>expr</var>
with argument <var>ld(0)</var> is 0 in the interval 0..<var>max</var>.
</p>
<p>The expression in <var>expr</var> must denote a continuous function or the
result is undefined.
</p>
<p><var>ld(0)</var> is used to represent the function input value, which means
that the given expression will be evaluated multiple times with
various input values that the expression can access through
<code>ld(0)</code>. When the expression evaluates to 0 then the
corresponding input value will be returned.
</p>
</dd>
<dt><samp>sin(x)</samp></dt>
<dd><p>Compute sine of <var>x</var>.
</p>
</dd>
<dt><samp>sinh(x)</samp></dt>
<dd><p>Compute hyperbolic sine of <var>x</var>.
</p>
</dd>
<dt><samp>sqrt(expr)</samp></dt>
<dd><p>Compute the square root of <var>expr</var>. This is equivalent to
"(<var>expr</var>)^.5".
</p>
</dd>
<dt><samp>squish(x)</samp></dt>
<dd><p>Compute expression <code>1/(1 + exp(4*x))</code>.
</p>
</dd>
<dt><samp>st(var, expr)</samp></dt>
<dd><p>Store the value of the expression <var>expr</var> in an internal
variable. <var>var</var> specifies the number of the variable where to
store the value, and it is a value ranging from 0 to 9. The function
returns the value stored in the internal variable.
Note, Variables are currently not shared between expressions.
</p>
</dd>
<dt><samp>tan(x)</samp></dt>
<dd><p>Compute tangent of <var>x</var>.
</p>
</dd>
<dt><samp>tanh(x)</samp></dt>
<dd><p>Compute hyperbolic tangent of <var>x</var>.
</p>
</dd>
<dt><samp>taylor(expr, x)</samp></dt>
<dt><samp>taylor(expr, x, id)</samp></dt>
<dd><p>Evaluate a Taylor series at <var>x</var>, given an expression representing
the <code>ld(id)</code>-th derivative of a function at 0.
</p>
<p>When the series does not converge the result is undefined.
</p>
<p><var>ld(id)</var> is used to represent the derivative order in <var>expr</var>,
which means that the given expression will be evaluated multiple times
with various input values that the expression can access through
<code>ld(id)</code>. If <var>id</var> is not specified then 0 is assumed.
</p>
<p>Note, when you have the derivatives at y instead of 0,
<code>taylor(expr, x-y)</code> can be used.
</p>
</dd>
<dt><samp>time(0)</samp></dt>
<dd><p>Return the current (wallclock) time in seconds.
</p>
</dd>
<dt><samp>trunc(expr)</samp></dt>
<dd><p>Round the value of expression <var>expr</var> towards zero to the nearest
integer. For example, "trunc(-1.5)" is "-1.0".
</p>
</dd>
<dt><samp>while(cond, expr)</samp></dt>
<dd><p>Evaluate expression <var>expr</var> while the expression <var>cond</var> is
non-zero, and returns the value of the last <var>expr</var> evaluation, or
NAN if <var>cond</var> was always false.
</p></dd>
</dl>
<p>The following constants are available:
</p><dl compact="compact">
<dt><samp>PI</samp></dt>
<dd><p>area of the unit disc, approximately 3.14
</p></dd>
<dt><samp>E</samp></dt>
<dd><p>exp(1) (Euler’s number), approximately 2.718
</p></dd>
<dt><samp>PHI</samp></dt>
<dd><p>golden ratio (1+sqrt(5))/2, approximately 1.618
</p></dd>
</dl>
<p>Assuming that an expression is considered "true" if it has a non-zero
value, note that:
</p>
<p><code>*</code> works like AND
</p>
<p><code>+</code> works like OR
</p>
<p>For example the construct:
</p><div class="example">
<pre class="example">if (A AND B) then C
</pre></div>
<p>is equivalent to:
</p><div class="example">
<pre class="example">if(A*B, C)
</pre></div>
<p>In your C code, you can extend the list of unary and binary functions,
and define recognized constants, so that they are available for your
expressions.
</p>
<p>The evaluator also recognizes the International System unit prefixes.
If ’i’ is appended after the prefix, binary prefixes are used, which
are based on powers of 1024 instead of powers of 1000.
The ’B’ postfix multiplies the value by 8, and can be appended after a
unit prefix or used alone. This allows using for example ’KB’, ’MiB’,
’G’ and ’B’ as number postfix.
</p>
<p>The list of available International System prefixes follows, with
indication of the corresponding powers of 10 and of 2.
</p><dl compact="compact">
<dt><samp>y</samp></dt>
<dd><p>10^-24 / 2^-80
</p></dd>
<dt><samp>z</samp></dt>
<dd><p>10^-21 / 2^-70
</p></dd>
<dt><samp>a</samp></dt>
<dd><p>10^-18 / 2^-60
</p></dd>
<dt><samp>f</samp></dt>
<dd><p>10^-15 / 2^-50
</p></dd>
<dt><samp>p</samp></dt>
<dd><p>10^-12 / 2^-40
</p></dd>
<dt><samp>n</samp></dt>
<dd><p>10^-9 / 2^-30
</p></dd>
<dt><samp>u</samp></dt>
<dd><p>10^-6 / 2^-20
</p></dd>
<dt><samp>m</samp></dt>
<dd><p>10^-3 / 2^-10
</p></dd>
<dt><samp>c</samp></dt>
<dd><p>10^-2
</p></dd>
<dt><samp>d</samp></dt>
<dd><p>10^-1
</p></dd>
<dt><samp>h</samp></dt>
<dd><p>10^2
</p></dd>
<dt><samp>k</samp></dt>
<dd><p>10^3 / 2^10
</p></dd>
<dt><samp>K</samp></dt>
<dd><p>10^3 / 2^10
</p></dd>
<dt><samp>M</samp></dt>
<dd><p>10^6 / 2^20
</p></dd>
<dt><samp>G</samp></dt>
<dd><p>10^9 / 2^30
</p></dd>
<dt><samp>T</samp></dt>
<dd><p>10^12 / 2^40
</p></dd>
<dt><samp>P</samp></dt>
<dd><p>10^15 / 2^40
</p></dd>
<dt><samp>E</samp></dt>
<dd><p>10^18 / 2^50
</p></dd>
<dt><samp>Z</samp></dt>
<dd><p>10^21 / 2^60
</p></dd>
<dt><samp>Y</samp></dt>
<dd><p>10^24 / 2^70
</p></dd>
</dl>
<a name="OpenCL-Options"></a>
<h2 class="chapter">9 OpenCL Options<span class="pull-right"><a class="anchor hidden-xs" href="#OpenCL-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-OpenCL-Options" aria-hidden="true">TOC</a></span></h2>
<p>When FFmpeg is configured with <code>--enable-opencl</code>, it is possible
to set the options for the global OpenCL context.
</p>
<p>The list of supported options follows:
</p>
<dl compact="compact">
<dt><samp>build_options</samp></dt>
<dd><p>Set build options used to compile the registered kernels.
</p>
<p>See reference "OpenCL Specification Version: 1.2 chapter 5.6.4".
</p>
</dd>
<dt><samp>platform_idx</samp></dt>
<dd><p>Select the index of the platform to run OpenCL code.
</p>
<p>The specified index must be one of the indexes in the device list
which can be obtained with <code>ffmpeg -opencl_bench</code> or <code>av_opencl_get_device_list()</code>.
</p>
</dd>
<dt><samp>device_idx</samp></dt>
<dd><p>Select the index of the device used to run OpenCL code.
</p>
<p>The specified index must be one of the indexes in the device list which
can be obtained with <code>ffmpeg -opencl_bench</code> or <code>av_opencl_get_device_list()</code>.
</p>
</dd>
</dl>
<a name="codec_002doptions"></a><a name="Codec-Options"></a>
<h2 class="chapter">10 Codec Options<span class="pull-right"><a class="anchor hidden-xs" href="#Codec-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Codec-Options" aria-hidden="true">TOC</a></span></h2>
<p>libavcodec provides some generic global options, which can be set on
all the encoders and decoders. In addition each codec may support
so-called private options, which are specific for a given codec.
</p>
<p>Sometimes, a global option may only affect a specific kind of codec,
and may be nonsensical or ignored by another, so you need to be aware
of the meaning of the specified options. Also some options are
meant only for decoding or encoding.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools, or by setting the value explicitly in the
<code>AVCodecContext</code> options or using the <samp>libavutil/opt.h</samp> API
for programmatic use.
</p>
<p>The list of supported options follow:
</p>
<dl compact="compact">
<dt><samp>b <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd><p>Set bitrate in bits/s. Default value is 200K.
</p>
</dd>
<dt><samp>ab <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set audio bitrate (in bits/s). Default value is 128K.
</p>
</dd>
<dt><samp>bt <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
tolerance specifies how far ratecontrol is willing to deviate from the
target average bitrate value. This is not related to min/max
bitrate. Lowering tolerance too much has an adverse effect on quality.
</p>
</dd>
<dt><samp>flags <var>flags</var> (<em>decoding/encoding,audio,video,subtitles</em>)</samp></dt>
<dd><p>Set generic flags.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>mv4</samp>’</dt>
<dd><p>Use four motion vector by macroblock (mpeg4).
</p></dd>
<dt>‘<samp>qpel</samp>’</dt>
<dd><p>Use 1/4 pel motion compensation.
</p></dd>
<dt>‘<samp>loop</samp>’</dt>
<dd><p>Use loop filter.
</p></dd>
<dt>‘<samp>qscale</samp>’</dt>
<dd><p>Use fixed qscale.
</p></dd>
<dt>‘<samp>gmc</samp>’</dt>
<dd><p>Use gmc.
</p></dd>
<dt>‘<samp>mv0</samp>’</dt>
<dd><p>Always try a mb with mv=<0,0>.
</p></dd>
<dt>‘<samp>input_preserved</samp>’</dt>
<dt>‘<samp>pass1</samp>’</dt>
<dd><p>Use internal 2pass ratecontrol in first pass mode.
</p></dd>
<dt>‘<samp>pass2</samp>’</dt>
<dd><p>Use internal 2pass ratecontrol in second pass mode.
</p></dd>
<dt>‘<samp>gray</samp>’</dt>
<dd><p>Only decode/encode grayscale.
</p></dd>
<dt>‘<samp>emu_edge</samp>’</dt>
<dd><p>Do not draw edges.
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>Set error[?] variables during encoding.
</p></dd>
<dt>‘<samp>truncated</samp>’</dt>
<dt>‘<samp>naq</samp>’</dt>
<dd><p>Normalize adaptive quantization.
</p></dd>
<dt>‘<samp>ildct</samp>’</dt>
<dd><p>Use interlaced DCT.
</p></dd>
<dt>‘<samp>low_delay</samp>’</dt>
<dd><p>Force low delay.
</p></dd>
<dt>‘<samp>global_header</samp>’</dt>
<dd><p>Place global headers in extradata instead of every keyframe.
</p></dd>
<dt>‘<samp>bitexact</samp>’</dt>
<dd><p>Only write platform-, build- and time-independent data. (except (I)DCT).
This ensures that file and data checksums are reproducible and match between
platforms. Its primary use is for regression testing.
</p></dd>
<dt>‘<samp>aic</samp>’</dt>
<dd><p>Apply H263 advanced intra coding / mpeg4 ac prediction.
</p></dd>
<dt>‘<samp>cbp</samp>’</dt>
<dd><p>Deprecated, use mpegvideo private options instead.
</p></dd>
<dt>‘<samp>qprd</samp>’</dt>
<dd><p>Deprecated, use mpegvideo private options instead.
</p></dd>
<dt>‘<samp>ilme</samp>’</dt>
<dd><p>Apply interlaced motion estimation.
</p></dd>
<dt>‘<samp>cgop</samp>’</dt>
<dd><p>Use closed gop.
</p></dd>
</dl>
</dd>
<dt><samp>me_method <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set motion estimation method.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>zero</samp>’</dt>
<dd><p>zero motion estimation (fastest)
</p></dd>
<dt>‘<samp>full</samp>’</dt>
<dd><p>full motion estimation (slowest)
</p></dd>
<dt>‘<samp>epzs</samp>’</dt>
<dd><p>EPZS motion estimation (default)
</p></dd>
<dt>‘<samp>esa</samp>’</dt>
<dd><p>esa motion estimation (alias for full)
</p></dd>
<dt>‘<samp>tesa</samp>’</dt>
<dd><p>tesa motion estimation
</p></dd>
<dt>‘<samp>dia</samp>’</dt>
<dd><p>dia motion estimation (alias for epzs)
</p></dd>
<dt>‘<samp>log</samp>’</dt>
<dd><p>log motion estimation
</p></dd>
<dt>‘<samp>phods</samp>’</dt>
<dd><p>phods motion estimation
</p></dd>
<dt>‘<samp>x1</samp>’</dt>
<dd><p>X1 motion estimation
</p></dd>
<dt>‘<samp>hex</samp>’</dt>
<dd><p>hex motion estimation
</p></dd>
<dt>‘<samp>umh</samp>’</dt>
<dd><p>umh motion estimation
</p></dd>
<dt>‘<samp>iter</samp>’</dt>
<dd><p>iter motion estimation
</p></dd>
</dl>
</dd>
<dt><samp>extradata_size <var>integer</var></samp></dt>
<dd><p>Set extradata size.
</p>
</dd>
<dt><samp>time_base <var>rational number</var></samp></dt>
<dd><p>Set codec time base.
</p>
<p>It is the fundamental unit of time (in seconds) in terms of which
frame timestamps are represented. For fixed-fps content, timebase
should be <code>1 / frame_rate</code> and timestamp increments should be
identically 1.
</p>
</dd>
<dt><samp>g <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set the group of picture size. Default value is 12.
</p>
</dd>
<dt><samp>ar <var>integer</var> (<em>decoding/encoding,audio</em>)</samp></dt>
<dd><p>Set audio sampling rate (in Hz).
</p>
</dd>
<dt><samp>ac <var>integer</var> (<em>decoding/encoding,audio</em>)</samp></dt>
<dd><p>Set number of audio channels.
</p>
</dd>
<dt><samp>cutoff <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set cutoff bandwidth.
</p>
</dd>
<dt><samp>frame_size <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set audio frame size.
</p>
<p>Each submitted frame except the last must contain exactly frame_size
samples per channel. May be 0 when the codec has
CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not
restricted. It is set by some decoders to indicate constant frame
size.
</p>
</dd>
<dt><samp>frame_number <var>integer</var></samp></dt>
<dd><p>Set the frame number.
</p>
</dd>
<dt><samp>delay <var>integer</var></samp></dt>
<dt><samp>qcomp <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video quantizer scale compression (VBR). It is used as a constant
in the ratecontrol equation. Recommended range for default rc_eq:
0.0-1.0.
</p>
</dd>
<dt><samp>qblur <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set video quantizer scale blur (VBR).
</p>
</dd>
<dt><samp>qmin <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set min video quantizer scale (VBR). Must be included between -1 and
69, default value is 2.
</p>
</dd>
<dt><samp>qmax <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set max video quantizer scale (VBR). Must be included between -1 and
1024, default value is 31.
</p>
</dd>
<dt><samp>qdiff <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set max difference between the quantizer scale (VBR).
</p>
</dd>
<dt><samp>bf <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set max number of B frames between non-B-frames.
</p>
<p>Must be an integer between -1 and 16. 0 means that B-frames are
disabled. If a value of -1 is used, it will choose an automatic value
depending on the encoder.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>b_qfactor <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set qp factor between P and B frames.
</p>
</dd>
<dt><samp>rc_strategy <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set ratecontrol method.
</p>
</dd>
<dt><samp>b_strategy <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set strategy to choose between I/P/B-frames.
</p>
</dd>
<dt><samp>ps <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set RTP payload size in bytes.
</p>
</dd>
<dt><samp>mv_bits <var>integer</var></samp></dt>
<dt><samp>header_bits <var>integer</var></samp></dt>
<dt><samp>i_tex_bits <var>integer</var></samp></dt>
<dt><samp>p_tex_bits <var>integer</var></samp></dt>
<dt><samp>i_count <var>integer</var></samp></dt>
<dt><samp>p_count <var>integer</var></samp></dt>
<dt><samp>skip_count <var>integer</var></samp></dt>
<dt><samp>misc_bits <var>integer</var></samp></dt>
<dt><samp>frame_bits <var>integer</var></samp></dt>
<dt><samp>codec_tag <var>integer</var></samp></dt>
<dt><samp>bug <var>flags</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Workaround not auto detected encoder bugs.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>autodetect</samp>’</dt>
<dt>‘<samp>old_msmpeg4</samp>’</dt>
<dd><p>some old lavc generated msmpeg4v3 files (no autodetection)
</p></dd>
<dt>‘<samp>xvid_ilace</samp>’</dt>
<dd><p>Xvid interlacing bug (autodetected if fourcc==XVIX)
</p></dd>
<dt>‘<samp>ump4</samp>’</dt>
<dd><p>(autodetected if fourcc==UMP4)
</p></dd>
<dt>‘<samp>no_padding</samp>’</dt>
<dd><p>padding bug (autodetected)
</p></dd>
<dt>‘<samp>amv</samp>’</dt>
<dt>‘<samp>ac_vlc</samp>’</dt>
<dd><p>illegal vlc bug (autodetected per fourcc)
</p></dd>
<dt>‘<samp>qpel_chroma</samp>’</dt>
<dt>‘<samp>std_qpel</samp>’</dt>
<dd><p>old standard qpel (autodetected per fourcc/version)
</p></dd>
<dt>‘<samp>qpel_chroma2</samp>’</dt>
<dt>‘<samp>direct_blocksize</samp>’</dt>
<dd><p>direct-qpel-blocksize bug (autodetected per fourcc/version)
</p></dd>
<dt>‘<samp>edge</samp>’</dt>
<dd><p>edge padding bug (autodetected per fourcc/version)
</p></dd>
<dt>‘<samp>hpel_chroma</samp>’</dt>
<dt>‘<samp>dc_clip</samp>’</dt>
<dt>‘<samp>ms</samp>’</dt>
<dd><p>Workaround various bugs in microsoft broken decoders.
</p></dd>
<dt>‘<samp>trunc</samp>’</dt>
<dd><p>trancated frames
</p></dd>
</dl>
</dd>
<dt><samp>lelim <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set single coefficient elimination threshold for luminance (negative
values also consider DC coefficient).
</p>
</dd>
<dt><samp>celim <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set single coefficient elimination threshold for chrominance (negative
values also consider dc coefficient)
</p>
</dd>
<dt><samp>strict <var>integer</var> (<em>decoding/encoding,audio,video</em>)</samp></dt>
<dd><p>Specify how strictly to follow the standards.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>very</samp>’</dt>
<dd><p>strictly conform to a older more strict version of the spec or reference software
</p></dd>
<dt>‘<samp>strict</samp>’</dt>
<dd><p>strictly conform to all the things in the spec no matter what consequences
</p></dd>
<dt>‘<samp>normal</samp>’</dt>
<dt>‘<samp>unofficial</samp>’</dt>
<dd><p>allow unofficial extensions
</p></dd>
<dt>‘<samp>experimental</samp>’</dt>
<dd><p>allow non standardized experimental things, experimental
(unfinished/work in progress/not well tested) decoders and encoders.
Note: experimental decoders can pose a security risk, do not use this for
decoding untrusted input.
</p></dd>
</dl>
</dd>
<dt><samp>b_qoffset <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set QP offset between P and B frames.
</p>
</dd>
<dt><samp>err_detect <var>flags</var> (<em>decoding,audio,video</em>)</samp></dt>
<dd><p>Set error detection flags.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>crccheck</samp>’</dt>
<dd><p>verify embedded CRCs
</p></dd>
<dt>‘<samp>bitstream</samp>’</dt>
<dd><p>detect bitstream specification deviations
</p></dd>
<dt>‘<samp>buffer</samp>’</dt>
<dd><p>detect improper bitstream length
</p></dd>
<dt>‘<samp>explode</samp>’</dt>
<dd><p>abort decoding on minor error detection
</p></dd>
<dt>‘<samp>ignore_err</samp>’</dt>
<dd><p>ignore decoding errors, and continue decoding.
This is useful if you want to analyze the content of a video and thus want
everything to be decoded no matter what. This option will not result in a video
that is pleasing to watch in case of errors.
</p></dd>
<dt>‘<samp>careful</samp>’</dt>
<dd><p>consider things that violate the spec and have not been seen in the wild as errors
</p></dd>
<dt>‘<samp>compliant</samp>’</dt>
<dd><p>consider all spec non compliancies as errors
</p></dd>
<dt>‘<samp>aggressive</samp>’</dt>
<dd><p>consider things that a sane encoder should not do as an error
</p></dd>
</dl>
</dd>
<dt><samp>has_b_frames <var>integer</var></samp></dt>
<dt><samp>block_align <var>integer</var></samp></dt>
<dt><samp>mpeg_quant <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Use MPEG quantizers instead of H.263.
</p>
</dd>
<dt><samp>qsquish <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>How to keep quantizer between qmin and qmax (0 = clip, 1 = use
differentiable function).
</p>
</dd>
<dt><samp>rc_qmod_amp <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set experimental quantizer modulation.
</p>
</dd>
<dt><samp>rc_qmod_freq <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set experimental quantizer modulation.
</p>
</dd>
<dt><samp>rc_override_count <var>integer</var></samp></dt>
<dt><samp>rc_eq <var>string</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set rate control equation. When computing the expression, besides the
standard functions defined in the section ’Expression Evaluation’, the
following functions are available: bits2qp(bits), qp2bits(qp). Also
the following constants are available: iTex pTex tex mv fCode iCount
mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex
avgTex.
</p>
</dd>
<dt><samp>maxrate <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd><p>Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
</p>
</dd>
<dt><samp>minrate <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd><p>Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
encode. It is of little use elsewise.
</p>
</dd>
<dt><samp>bufsize <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd><p>Set ratecontrol buffer size (in bits).
</p>
</dd>
<dt><samp>rc_buf_aggressivity <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Currently useless.
</p>
</dd>
<dt><samp>i_qfactor <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set QP factor between P and I frames.
</p>
</dd>
<dt><samp>i_qoffset <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set QP offset between P and I frames.
</p>
</dd>
<dt><samp>rc_init_cplx <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set initial complexity for 1-pass encoding.
</p>
</dd>
<dt><samp>dct <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set DCT algorithm.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>autoselect a good one (default)
</p></dd>
<dt>‘<samp>fastint</samp>’</dt>
<dd><p>fast integer
</p></dd>
<dt>‘<samp>int</samp>’</dt>
<dd><p>accurate integer
</p></dd>
<dt>‘<samp>mmx</samp>’</dt>
<dt>‘<samp>altivec</samp>’</dt>
<dt>‘<samp>faan</samp>’</dt>
<dd><p>floating point AAN DCT
</p></dd>
</dl>
</dd>
<dt><samp>lumi_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Compress bright areas stronger than medium ones.
</p>
</dd>
<dt><samp>tcplx_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set temporal complexity masking.
</p>
</dd>
<dt><samp>scplx_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set spatial complexity masking.
</p>
</dd>
<dt><samp>p_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set inter masking.
</p>
</dd>
<dt><samp>dark_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Compress dark areas stronger than medium ones.
</p>
</dd>
<dt><samp>idct <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dd><p>Select IDCT implementation.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dt>‘<samp>int</samp>’</dt>
<dt>‘<samp>simple</samp>’</dt>
<dt>‘<samp>simplemmx</samp>’</dt>
<dt>‘<samp>simpleauto</samp>’</dt>
<dd><p>Automatically pick a IDCT compatible with the simple one
</p>
</dd>
<dt>‘<samp>arm</samp>’</dt>
<dt>‘<samp>altivec</samp>’</dt>
<dt>‘<samp>sh4</samp>’</dt>
<dt>‘<samp>simplearm</samp>’</dt>
<dt>‘<samp>simplearmv5te</samp>’</dt>
<dt>‘<samp>simplearmv6</samp>’</dt>
<dt>‘<samp>simpleneon</samp>’</dt>
<dt>‘<samp>simplealpha</samp>’</dt>
<dt>‘<samp>ipp</samp>’</dt>
<dt>‘<samp>xvidmmx</samp>’</dt>
<dt>‘<samp>faani</samp>’</dt>
<dd><p>floating point AAN IDCT
</p></dd>
</dl>
</dd>
<dt><samp>slice_count <var>integer</var></samp></dt>
<dt><samp>ec <var>flags</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Set error concealment strategy.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>guess_mvs</samp>’</dt>
<dd><p>iterative motion vector (MV) search (slow)
</p></dd>
<dt>‘<samp>deblock</samp>’</dt>
<dd><p>use strong deblock filter for damaged MBs
</p></dd>
<dt>‘<samp>favor_inter</samp>’</dt>
<dd><p>favor predicting from the previous frame instead of the current
</p></dd>
</dl>
</dd>
<dt><samp>bits_per_coded_sample <var>integer</var></samp></dt>
<dt><samp>pred <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set prediction method.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>left</samp>’</dt>
<dt>‘<samp>plane</samp>’</dt>
<dt>‘<samp>median</samp>’</dt>
</dl>
</dd>
<dt><samp>aspect <var>rational number</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set sample aspect ratio.
</p>
</dd>
<dt><samp>debug <var>flags</var> (<em>decoding/encoding,audio,video,subtitles</em>)</samp></dt>
<dd><p>Print specific debug info.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>pict</samp>’</dt>
<dd><p>picture info
</p></dd>
<dt>‘<samp>rc</samp>’</dt>
<dd><p>rate control
</p></dd>
<dt>‘<samp>bitstream</samp>’</dt>
<dt>‘<samp>mb_type</samp>’</dt>
<dd><p>macroblock (MB) type
</p></dd>
<dt>‘<samp>qp</samp>’</dt>
<dd><p>per-block quantization parameter (QP)
</p></dd>
<dt>‘<samp>mv</samp>’</dt>
<dd><p>motion vector
</p></dd>
<dt>‘<samp>dct_coeff</samp>’</dt>
<dt>‘<samp>green_metadata</samp>’</dt>
<dd><p>display complexity metadata for the upcoming frame, GoP or for a given duration.
</p>
</dd>
<dt>‘<samp>skip</samp>’</dt>
<dt>‘<samp>startcode</samp>’</dt>
<dt>‘<samp>pts</samp>’</dt>
<dt>‘<samp>er</samp>’</dt>
<dd><p>error recognition
</p></dd>
<dt>‘<samp>mmco</samp>’</dt>
<dd><p>memory management control operations (H.264)
</p></dd>
<dt>‘<samp>bugs</samp>’</dt>
<dt>‘<samp>vis_qp</samp>’</dt>
<dd><p>visualize quantization parameter (QP), lower QP are tinted greener
</p></dd>
<dt>‘<samp>vis_mb_type</samp>’</dt>
<dd><p>visualize block types
</p></dd>
<dt>‘<samp>buffers</samp>’</dt>
<dd><p>picture buffer allocations
</p></dd>
<dt>‘<samp>thread_ops</samp>’</dt>
<dd><p>threading operations
</p></dd>
<dt>‘<samp>nomc</samp>’</dt>
<dd><p>skip motion compensation
</p></dd>
</dl>
</dd>
<dt><samp>vismv <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Visualize motion vectors (MVs).
</p>
<p>This option is deprecated, see the codecview filter instead.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>pf</samp>’</dt>
<dd><p>forward predicted MVs of P-frames
</p></dd>
<dt>‘<samp>bf</samp>’</dt>
<dd><p>forward predicted MVs of B-frames
</p></dd>
<dt>‘<samp>bb</samp>’</dt>
<dd><p>backward predicted MVs of B-frames
</p></dd>
</dl>
</dd>
<dt><samp>cmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set full pel me compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>subcmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set sub pel me compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>mbcmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set macroblock compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>ildctcmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set interlaced dct compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>dia_size <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set diamond type & size for motion estimation.
</p>
</dd>
<dt><samp>last_pred <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set amount of motion predictors from the previous frame.
</p>
</dd>
<dt><samp>preme <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set pre motion estimation.
</p>
</dd>
<dt><samp>precmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set pre motion estimation compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>pre_dia_size <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set diamond type & size for motion estimation pre-pass.
</p>
</dd>
<dt><samp>subq <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set sub pel motion estimation quality.
</p>
</dd>
<dt><samp>dtg_active_format <var>integer</var></samp></dt>
<dt><samp>me_range <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set limit motion vectors range (1023 for DivX player).
</p>
</dd>
<dt><samp>ibias <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set intra quant bias.
</p>
</dd>
<dt><samp>pbias <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set inter quant bias.
</p>
</dd>
<dt><samp>color_table_id <var>integer</var></samp></dt>
<dt><samp>global_quality <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dt><samp>coder <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>vlc</samp>’</dt>
<dd><p>variable length coder / huffman coder
</p></dd>
<dt>‘<samp>ac</samp>’</dt>
<dd><p>arithmetic coder
</p></dd>
<dt>‘<samp>raw</samp>’</dt>
<dd><p>raw (no encoding)
</p></dd>
<dt>‘<samp>rle</samp>’</dt>
<dd><p>run-length coder
</p></dd>
<dt>‘<samp>deflate</samp>’</dt>
<dd><p>deflate-based coder
</p></dd>
</dl>
</dd>
<dt><samp>context <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set context model.
</p>
</dd>
<dt><samp>slice_flags <var>integer</var></samp></dt>
<dt><samp>xvmc_acceleration <var>integer</var></samp></dt>
<dt><samp>mbd <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set macroblock decision algorithm (high quality mode).
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>simple</samp>’</dt>
<dd><p>use mbcmp (default)
</p></dd>
<dt>‘<samp>bits</samp>’</dt>
<dd><p>use fewest bits
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>use best rate distortion
</p></dd>
</dl>
</dd>
<dt><samp>stream_codec_tag <var>integer</var></samp></dt>
<dt><samp>sc_threshold <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set scene change threshold.
</p>
</dd>
<dt><samp>lmin <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set min lagrange factor (VBR).
</p>
</dd>
<dt><samp>lmax <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set max lagrange factor (VBR).
</p>
</dd>
<dt><samp>nr <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set noise reduction.
</p>
</dd>
<dt><samp>rc_init_occupancy <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set number of bits which should be loaded into the rc buffer before
decoding starts.
</p>
</dd>
<dt><samp>flags2 <var>flags</var> (<em>decoding/encoding,audio,video</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>fast</samp>’</dt>
<dd><p>Allow non spec compliant speedup tricks.
</p></dd>
<dt>‘<samp>sgop</samp>’</dt>
<dd><p>Deprecated, use mpegvideo private options instead.
</p></dd>
<dt>‘<samp>noout</samp>’</dt>
<dd><p>Skip bitstream encoding.
</p></dd>
<dt>‘<samp>ignorecrop</samp>’</dt>
<dd><p>Ignore cropping information from sps.
</p></dd>
<dt>‘<samp>local_header</samp>’</dt>
<dd><p>Place global headers at every keyframe instead of in extradata.
</p></dd>
<dt>‘<samp>chunks</samp>’</dt>
<dd><p>Frame data might be split into multiple chunks.
</p></dd>
<dt>‘<samp>showall</samp>’</dt>
<dd><p>Show all frames before the first keyframe.
</p></dd>
<dt>‘<samp>skiprd</samp>’</dt>
<dd><p>Deprecated, use mpegvideo private options instead.
</p></dd>
<dt>‘<samp>export_mvs</samp>’</dt>
<dd><p>Export motion vectors into frame side-data (see <code>AV_FRAME_DATA_MOTION_VECTORS</code>)
for codecs that support it. See also <samp>doc/examples/export_mvs.c</samp>.
</p></dd>
</dl>
</dd>
<dt><samp>error <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>qns <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Deprecated, use mpegvideo private options instead.
</p>
</dd>
<dt><samp>threads <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>detect a good number of threads
</p></dd>
</dl>
</dd>
<dt><samp>me_threshold <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set motion estimation threshold.
</p>
</dd>
<dt><samp>mb_threshold <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set macroblock threshold.
</p>
</dd>
<dt><samp>dc <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set intra_dc_precision.
</p>
</dd>
<dt><samp>nssew <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set nsse weight.
</p>
</dd>
<dt><samp>skip_top <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Set number of macroblock rows at the top which are skipped.
</p>
</dd>
<dt><samp>skip_bottom <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Set number of macroblock rows at the bottom which are skipped.
</p>
</dd>
<dt><samp>profile <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>unknown</samp>’</dt>
<dt>‘<samp>aac_main</samp>’</dt>
<dt>‘<samp>aac_low</samp>’</dt>
<dt>‘<samp>aac_ssr</samp>’</dt>
<dt>‘<samp>aac_ltp</samp>’</dt>
<dt>‘<samp>aac_he</samp>’</dt>
<dt>‘<samp>aac_he_v2</samp>’</dt>
<dt>‘<samp>aac_ld</samp>’</dt>
<dt>‘<samp>aac_eld</samp>’</dt>
<dt>‘<samp>mpeg2_aac_low</samp>’</dt>
<dt>‘<samp>mpeg2_aac_he</samp>’</dt>
<dt>‘<samp>mpeg4_sp</samp>’</dt>
<dt>‘<samp>mpeg4_core</samp>’</dt>
<dt>‘<samp>mpeg4_main</samp>’</dt>
<dt>‘<samp>mpeg4_asp</samp>’</dt>
<dt>‘<samp>dts</samp>’</dt>
<dt>‘<samp>dts_es</samp>’</dt>
<dt>‘<samp>dts_96_24</samp>’</dt>
<dt>‘<samp>dts_hd_hra</samp>’</dt>
<dt>‘<samp>dts_hd_ma</samp>’</dt>
</dl>
</dd>
<dt><samp>level <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>unknown</samp>’</dt>
</dl>
</dd>
<dt><samp>lowres <var>integer</var> (<em>decoding,audio,video</em>)</samp></dt>
<dd><p>Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.
</p>
</dd>
<dt><samp>skip_threshold <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set frame skip threshold.
</p>
</dd>
<dt><samp>skip_factor <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set frame skip factor.
</p>
</dd>
<dt><samp>skip_exp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set frame skip exponent.
Negative values behave identical to the corresponding positive ones, except
that the score is normalized.
Positive values exist primarily for compatibility reasons and are not so useful.
</p>
</dd>
<dt><samp>skipcmp <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set frame skip compare function.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>sad</samp>’</dt>
<dd><p>sum of absolute differences, fast (default)
</p></dd>
<dt>‘<samp>sse</samp>’</dt>
<dd><p>sum of squared errors
</p></dd>
<dt>‘<samp>satd</samp>’</dt>
<dd><p>sum of absolute Hadamard transformed differences
</p></dd>
<dt>‘<samp>dct</samp>’</dt>
<dd><p>sum of absolute DCT transformed differences
</p></dd>
<dt>‘<samp>psnr</samp>’</dt>
<dd><p>sum of squared quantization errors (avoid, low quality)
</p></dd>
<dt>‘<samp>bit</samp>’</dt>
<dd><p>number of bits needed for the block
</p></dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>rate distortion optimal, slow
</p></dd>
<dt>‘<samp>zero</samp>’</dt>
<dd><p>0
</p></dd>
<dt>‘<samp>vsad</samp>’</dt>
<dd><p>sum of absolute vertical differences
</p></dd>
<dt>‘<samp>vsse</samp>’</dt>
<dd><p>sum of squared vertical differences
</p></dd>
<dt>‘<samp>nsse</samp>’</dt>
<dd><p>noise preserving sum of squared differences
</p></dd>
<dt>‘<samp>w53</samp>’</dt>
<dd><p>5/3 wavelet, only used in snow
</p></dd>
<dt>‘<samp>w97</samp>’</dt>
<dd><p>9/7 wavelet, only used in snow
</p></dd>
<dt>‘<samp>dctmax</samp>’</dt>
<dt>‘<samp>chroma</samp>’</dt>
</dl>
</dd>
<dt><samp>border_mask <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Increase the quantizer for macroblocks close to borders.
</p>
</dd>
<dt><samp>mblmin <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set min macroblock lagrange factor (VBR).
</p>
</dd>
<dt><samp>mblmax <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set max macroblock lagrange factor (VBR).
</p>
</dd>
<dt><samp>mepc <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set motion estimation bitrate penalty compensation (1.0 = 256).
</p>
</dd>
<dt><samp>skip_loop_filter <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dt><samp>skip_idct <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dt><samp>skip_frame <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dd>
<p>Make decoder discard processing depending on the frame type selected
by the option value.
</p>
<p><samp>skip_loop_filter</samp> skips frame loop filtering, <samp>skip_idct</samp>
skips frame IDCT/dequantization, <samp>skip_frame</samp> skips decoding.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>Discard no frame.
</p>
</dd>
<dt>‘<samp>default</samp>’</dt>
<dd><p>Discard useless frames like 0-sized frames.
</p>
</dd>
<dt>‘<samp>noref</samp>’</dt>
<dd><p>Discard all non-reference frames.
</p>
</dd>
<dt>‘<samp>bidir</samp>’</dt>
<dd><p>Discard all bidirectional frames.
</p>
</dd>
<dt>‘<samp>nokey</samp>’</dt>
<dd><p>Discard all frames excepts keyframes.
</p>
</dd>
<dt>‘<samp>all</samp>’</dt>
<dd><p>Discard all frames.
</p></dd>
</dl>
<p>Default value is ‘<samp>default</samp>’.
</p>
</dd>
<dt><samp>bidir_refine <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Refine the two motion vectors used in bidirectional macroblocks.
</p>
</dd>
<dt><samp>brd_scale <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Downscale frames for dynamic B-frame decision.
</p>
</dd>
<dt><samp>keyint_min <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set minimum interval between IDR-frames.
</p>
</dd>
<dt><samp>refs <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set reference frames to consider for motion compensation.
</p>
</dd>
<dt><samp>chromaoffset <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set chroma qp offset from luma.
</p>
</dd>
<dt><samp>trellis <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dd><p>Set rate-distortion optimal quantization.
</p>
</dd>
<dt><samp>sc_factor <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set value multiplied by qscale for each frame and added to
scene_change_score.
</p>
</dd>
<dt><samp>mv0_threshold <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>b_sensitivity <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Adjust sensitivity of b_frame_strategy 1.
</p>
</dd>
<dt><samp>compression_level <var>integer</var> (<em>encoding,audio,video</em>)</samp></dt>
<dt><samp>min_prediction_order <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dt><samp>max_prediction_order <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dt><samp>timecode_frame_start <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Set GOP timecode frame start number, in non drop frame format.
</p>
</dd>
<dt><samp>request_channels <var>integer</var> (<em>decoding,audio</em>)</samp></dt>
<dd><p>Set desired number of audio channels.
</p>
</dd>
<dt><samp>bits_per_raw_sample <var>integer</var></samp></dt>
<dt><samp>channel_layout <var>integer</var> (<em>decoding/encoding,audio</em>)</samp></dt>
<dd>
<p>Possible values:
</p></dd>
<dt><samp>request_channel_layout <var>integer</var> (<em>decoding,audio</em>)</samp></dt>
<dd>
<p>Possible values:
</p></dd>
<dt><samp>rc_max_vbv_use <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>rc_min_vbv_use <var>float</var> (<em>encoding,video</em>)</samp></dt>
<dt><samp>ticks_per_frame <var>integer</var> (<em>decoding/encoding,audio,video</em>)</samp></dt>
<dt><samp>color_primaries <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dt><samp>color_trc <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dt><samp>colorspace <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dt><samp>color_range <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dd><p>If used as input parameter, it serves as a hint to the decoder, which
color_range the input has.
</p>
</dd>
<dt><samp>chroma_sample_location <var>integer</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dt><samp>log_level_offset <var>integer</var></samp></dt>
<dd><p>Set the log level offset.
</p>
</dd>
<dt><samp>slices <var>integer</var> (<em>encoding,video</em>)</samp></dt>
<dd><p>Number of slices, used in parallelized encoding.
</p>
</dd>
<dt><samp>thread_type <var>flags</var> (<em>decoding/encoding,video</em>)</samp></dt>
<dd><p>Select which multithreading methods to use.
</p>
<p>Use of ‘<samp>frame</samp>’ will increase decoding delay by one frame per
thread, so clients which cannot provide future frames should not use
it.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>slice</samp>’</dt>
<dd><p>Decode more than one part of a single frame at once.
</p>
<p>Multithreading using slices works only when the video was encoded with
slices.
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>Decode more than one frame at once.
</p></dd>
</dl>
<p>Default value is ‘<samp>slice+frame</samp>’.
</p>
</dd>
<dt><samp>audio_service_type <var>integer</var> (<em>encoding,audio</em>)</samp></dt>
<dd><p>Set audio service type.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>ma</samp>’</dt>
<dd><p>Main Audio Service
</p></dd>
<dt>‘<samp>ef</samp>’</dt>
<dd><p>Effects
</p></dd>
<dt>‘<samp>vi</samp>’</dt>
<dd><p>Visually Impaired
</p></dd>
<dt>‘<samp>hi</samp>’</dt>
<dd><p>Hearing Impaired
</p></dd>
<dt>‘<samp>di</samp>’</dt>
<dd><p>Dialogue
</p></dd>
<dt>‘<samp>co</samp>’</dt>
<dd><p>Commentary
</p></dd>
<dt>‘<samp>em</samp>’</dt>
<dd><p>Emergency
</p></dd>
<dt>‘<samp>vo</samp>’</dt>
<dd><p>Voice Over
</p></dd>
<dt>‘<samp>ka</samp>’</dt>
<dd><p>Karaoke
</p></dd>
</dl>
</dd>
<dt><samp>request_sample_fmt <var>sample_fmt</var> (<em>decoding,audio</em>)</samp></dt>
<dd><p>Set sample format audio decoders should prefer. Default value is
<code>none</code>.
</p>
</dd>
<dt><samp>pkt_timebase <var>rational number</var></samp></dt>
<dt><samp>sub_charenc <var>encoding</var> (<em>decoding,subtitles</em>)</samp></dt>
<dd><p>Set the input subtitles character encoding.
</p>
</dd>
<dt><samp>field_order <var>field_order</var> (<em>video</em>)</samp></dt>
<dd><p>Set/override the field order of the video.
Possible values:
</p><dl compact="compact">
<dt>‘<samp>progressive</samp>’</dt>
<dd><p>Progressive video
</p></dd>
<dt>‘<samp>tt</samp>’</dt>
<dd><p>Interlaced video, top field coded and displayed first
</p></dd>
<dt>‘<samp>bb</samp>’</dt>
<dd><p>Interlaced video, bottom field coded and displayed first
</p></dd>
<dt>‘<samp>tb</samp>’</dt>
<dd><p>Interlaced video, top coded first, bottom displayed first
</p></dd>
<dt>‘<samp>bt</samp>’</dt>
<dd><p>Interlaced video, bottom coded first, top displayed first
</p></dd>
</dl>
</dd>
<dt><samp>skip_alpha <var>integer</var> (<em>decoding,video</em>)</samp></dt>
<dd><p>Set to 1 to disable processing alpha (transparency). This works like the
‘<samp>gray</samp>’ flag in the <samp>flags</samp> option which skips chroma information
instead of alpha. Default is 0.
</p>
</dd>
<dt><samp>codec_whitelist <var>list</var> (<em>input</em>)</samp></dt>
<dd><p>"," separated List of allowed decoders. By default all are allowed.
</p>
</dd>
<dt><samp>dump_separator <var>string</var> (<em>input</em>)</samp></dt>
<dd><p>Separator used to separate the fields printed on the command line about the
Stream parameters.
For example to separate the fields with newlines and indention:
</p><div class="example">
<pre class="example">ffprobe -dump_separator "
" -i ~/videos/matrixbench_mpeg2.mpg
</pre></div>
</dd>
</dl>
<a name="Decoders"></a>
<h2 class="chapter">11 Decoders<span class="pull-right"><a class="anchor hidden-xs" href="#Decoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Decoders" aria-hidden="true">TOC</a></span></h2>
<p>Decoders are configured elements in FFmpeg which allow the decoding of
multimedia streams.
</p>
<p>When you configure your FFmpeg build, all the supported native decoders
are enabled by default. Decoders requiring an external library must be enabled
manually via the corresponding <code>--enable-lib</code> option. You can list all
available decoders using the configure option <code>--list-decoders</code>.
</p>
<p>You can disable all the decoders with the configure option
<code>--disable-decoders</code> and selectively enable / disable single decoders
with the options <code>--enable-decoder=<var>DECODER</var></code> /
<code>--disable-decoder=<var>DECODER</var></code>.
</p>
<p>The option <code>-decoders</code> of the ff* tools will display the list of
enabled decoders.
</p>
<a name="Video-Decoders"></a>
<h2 class="chapter">12 Video Decoders<span class="pull-right"><a class="anchor hidden-xs" href="#Video-Decoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-Decoders" aria-hidden="true">TOC</a></span></h2>
<p>A description of some of the currently available video decoders
follows.
</p>
<a name="hevc"></a>
<h3 class="section">12.1 hevc<span class="pull-right"><a class="anchor hidden-xs" href="#hevc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hevc" aria-hidden="true">TOC</a></span></h3>
<p>HEVC / H.265 decoder.
</p>
<p>Note: the <samp>skip_loop_filter</samp> option has effect only at level
<code>all</code>.
</p>
<a name="rawvideo"></a>
<h3 class="section">12.2 rawvideo<span class="pull-right"><a class="anchor hidden-xs" href="#rawvideo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rawvideo" aria-hidden="true">TOC</a></span></h3>
<p>Raw video decoder.
</p>
<p>This decoder decodes rawvideo streams.
</p>
<a name="Options-1"></a>
<h4 class="subsection">12.2.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-1" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>top <var>top_field_first</var></samp></dt>
<dd><p>Specify the assumed field type of the input video.
</p><dl compact="compact">
<dt><samp>-1</samp></dt>
<dd><p>the video is assumed to be progressive (default)
</p></dd>
<dt><samp>0</samp></dt>
<dd><p>bottom-field-first is assumed
</p></dd>
<dt><samp>1</samp></dt>
<dd><p>top-field-first is assumed
</p></dd>
</dl>
</dd>
</dl>
<a name="Audio-Decoders"></a>
<h2 class="chapter">13 Audio Decoders<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Decoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Decoders" aria-hidden="true">TOC</a></span></h2>
<p>A description of some of the currently available audio decoders
follows.
</p>
<a name="ac3"></a>
<h3 class="section">13.1 ac3<span class="pull-right"><a class="anchor hidden-xs" href="#ac3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ac3" aria-hidden="true">TOC</a></span></h3>
<p>AC-3 audio decoder.
</p>
<p>This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
the undocumented RealAudio 3 (a.k.a. dnet).
</p>
<a name="AC_002d3-Decoder-Options"></a>
<h4 class="subsection">13.1.1 AC-3 Decoder Options<span class="pull-right"><a class="anchor hidden-xs" href="#AC_002d3-Decoder-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-AC_002d3-Decoder-Options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-drc_scale <var>value</var></samp></dt>
<dd><p>Dynamic Range Scale Factor. The factor to apply to dynamic range values
from the AC-3 stream. This factor is applied exponentially.
There are 3 notable scale factor ranges:
</p><dl compact="compact">
<dt><samp>drc_scale == 0</samp></dt>
<dd><p>DRC disabled. Produces full range audio.
</p></dd>
<dt><samp>0 < drc_scale <= 1</samp></dt>
<dd><p>DRC enabled. Applies a fraction of the stream DRC value.
Audio reproduction is between full range and full compression.
</p></dd>
<dt><samp>drc_scale > 1</samp></dt>
<dd><p>DRC enabled. Applies drc_scale asymmetrically.
Loud sounds are fully compressed. Soft sounds are enhanced.
</p></dd>
</dl>
</dd>
</dl>
<a name="flac-1"></a>
<h3 class="section">13.2 flac<span class="pull-right"><a class="anchor hidden-xs" href="#flac-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-flac-1" aria-hidden="true">TOC</a></span></h3>
<p>FLAC audio decoder.
</p>
<p>This decoder aims to implement the complete FLAC specification from Xiph.
</p>
<a name="FLAC-Decoder-options"></a>
<h4 class="subsection">13.2.1 FLAC Decoder options<span class="pull-right"><a class="anchor hidden-xs" href="#FLAC-Decoder-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-FLAC-Decoder-options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-use_buggy_lpc</samp></dt>
<dd><p>The lavc FLAC encoder used to produce buggy streams with high lpc values
(like the default value). This option makes it possible to decode such streams
correctly by using lavc’s old buggy lpc logic for decoding.
</p>
</dd>
</dl>
<a name="ffwavesynth"></a>
<h3 class="section">13.3 ffwavesynth<span class="pull-right"><a class="anchor hidden-xs" href="#ffwavesynth" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ffwavesynth" aria-hidden="true">TOC</a></span></h3>
<p>Internal wave synthetizer.
</p>
<p>This decoder generates wave patterns according to predefined sequences. Its
use is purely internal and the format of the data it accepts is not publicly
documented.
</p>
<a name="libcelt"></a>
<h3 class="section">13.4 libcelt<span class="pull-right"><a class="anchor hidden-xs" href="#libcelt" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libcelt" aria-hidden="true">TOC</a></span></h3>
<p>libcelt decoder wrapper.
</p>
<p>libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
Requires the presence of the libcelt headers and library during configuration.
You need to explicitly configure the build with <code>--enable-libcelt</code>.
</p>
<a name="libgsm"></a>
<h3 class="section">13.5 libgsm<span class="pull-right"><a class="anchor hidden-xs" href="#libgsm" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libgsm" aria-hidden="true">TOC</a></span></h3>
<p>libgsm decoder wrapper.
</p>
<p>libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
the presence of the libgsm headers and library during configuration. You need
to explicitly configure the build with <code>--enable-libgsm</code>.
</p>
<p>This decoder supports both the ordinary GSM and the Microsoft variant.
</p>
<a name="libilbc"></a>
<h3 class="section">13.6 libilbc<span class="pull-right"><a class="anchor hidden-xs" href="#libilbc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libilbc" aria-hidden="true">TOC</a></span></h3>
<p>libilbc decoder wrapper.
</p>
<p>libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
audio codec. Requires the presence of the libilbc headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libilbc</code>.
</p>
<a name="Options-2"></a>
<h4 class="subsection">13.6.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-2" aria-hidden="true">TOC</a></span></h4>
<p>The following option is supported by the libilbc wrapper.
</p>
<dl compact="compact">
<dt><samp>enhance</samp></dt>
<dd>
<p>Enable the enhancement of the decoded audio when set to 1. The default
value is 0 (disabled).
</p>
</dd>
</dl>
<a name="libopencore_002damrnb"></a>
<h3 class="section">13.7 libopencore-amrnb<span class="pull-right"><a class="anchor hidden-xs" href="#libopencore_002damrnb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libopencore_002damrnb" aria-hidden="true">TOC</a></span></h3>
<p>libopencore-amrnb decoder wrapper.
</p>
<p>libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
Narrowband audio codec. Using it requires the presence of the
libopencore-amrnb headers and library during configuration. You need to
explicitly configure the build with <code>--enable-libopencore-amrnb</code>.
</p>
<p>An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
without this library.
</p>
<a name="libopencore_002damrwb"></a>
<h3 class="section">13.8 libopencore-amrwb<span class="pull-right"><a class="anchor hidden-xs" href="#libopencore_002damrwb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libopencore_002damrwb" aria-hidden="true">TOC</a></span></h3>
<p>libopencore-amrwb decoder wrapper.
</p>
<p>libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
Wideband audio codec. Using it requires the presence of the
libopencore-amrwb headers and library during configuration. You need to
explicitly configure the build with <code>--enable-libopencore-amrwb</code>.
</p>
<p>An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
without this library.
</p>
<a name="libopus"></a>
<h3 class="section">13.9 libopus<span class="pull-right"><a class="anchor hidden-xs" href="#libopus" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libopus" aria-hidden="true">TOC</a></span></h3>
<p>libopus decoder wrapper.
</p>
<p>libopus allows libavcodec to decode the Opus Interactive Audio Codec.
Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libopus</code>.
</p>
<p>An FFmpeg native decoder for Opus exists, so users can decode Opus
without this library.
</p>
<a name="Subtitles-Decoders"></a>
<h2 class="chapter">14 Subtitles Decoders<span class="pull-right"><a class="anchor hidden-xs" href="#Subtitles-Decoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Subtitles-Decoders" aria-hidden="true">TOC</a></span></h2>
<a name="dvbsub"></a>
<h3 class="section">14.1 dvbsub<span class="pull-right"><a class="anchor hidden-xs" href="#dvbsub" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dvbsub" aria-hidden="true">TOC</a></span></h3>
<a name="Options-3"></a>
<h4 class="subsection">14.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-3" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>compute_clut</samp></dt>
<dd><dl compact="compact">
<dt><samp>-1</samp></dt>
<dd><p>Compute clut if no matching CLUT is in the stream.
</p></dd>
<dt><samp>0</samp></dt>
<dd><p>Never compute CLUT
</p></dd>
<dt><samp>1</samp></dt>
<dd><p>Always compute CLUT and override the one provided in the stream.
</p></dd>
</dl>
</dd>
<dt><samp>dvb_substream</samp></dt>
<dd><p>Selects the dvb substream, or all substreams if -1 which is default.
</p>
</dd>
</dl>
<a name="dvdsub"></a>
<h3 class="section">14.2 dvdsub<span class="pull-right"><a class="anchor hidden-xs" href="#dvdsub" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dvdsub" aria-hidden="true">TOC</a></span></h3>
<p>This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
also be found in VobSub file pairs and in some Matroska files.
</p>
<a name="Options-4"></a>
<h4 class="subsection">14.2.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-4" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-4" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>palette</samp></dt>
<dd><p>Specify the global palette used by the bitmaps. When stored in VobSub, the
palette is normally specified in the index file; in Matroska, the palette is
stored in the codec extra-data in the same format as in VobSub. In DVDs, the
palette is stored in the IFO file, and therefore not available when reading
from dumped VOB files.
</p>
<p>The format for this option is a string containing 16 24-bits hexadecimal
numbers (without 0x prefix) separated by comas, for example <code>0d00ee,
ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b</code>.
</p>
</dd>
<dt><samp>ifo_palette</samp></dt>
<dd><p>Specify the IFO file from which the global palette is obtained.
(experimental)
</p>
</dd>
<dt><samp>forced_subs_only</samp></dt>
<dd><p>Only decode subtitle entries marked as forced. Some titles have forced
and non-forced subtitles in the same track. Setting this flag to <code>1</code>
will only keep the forced subtitles. Default value is <code>0</code>.
</p></dd>
</dl>
<a name="libzvbi_002dteletext"></a>
<h3 class="section">14.3 libzvbi-teletext<span class="pull-right"><a class="anchor hidden-xs" href="#libzvbi_002dteletext" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libzvbi_002dteletext" aria-hidden="true">TOC</a></span></h3>
<p>Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
subtitles. Requires the presence of the libzvbi headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libzvbi</code>.
</p>
<a name="Options-5"></a>
<h4 class="subsection">14.3.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-5" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-5" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>txt_page</samp></dt>
<dd><p>List of teletext page numbers to decode. You may use the special * string to
match all pages. Pages that do not match the specified list are dropped.
Default value is *.
</p></dd>
<dt><samp>txt_chop_top</samp></dt>
<dd><p>Discards the top teletext line. Default value is 1.
</p></dd>
<dt><samp>txt_format</samp></dt>
<dd><p>Specifies the format of the decoded subtitles. The teletext decoder is capable
of decoding the teletext pages to bitmaps or to simple text, you should use
"bitmap" for teletext pages, because certain graphics and colors cannot be
expressed in simple text. You might use "text" for teletext based subtitles if
your application can handle simple text based subtitles. Default value is
bitmap.
</p></dd>
<dt><samp>txt_left</samp></dt>
<dd><p>X offset of generated bitmaps, default is 0.
</p></dd>
<dt><samp>txt_top</samp></dt>
<dd><p>Y offset of generated bitmaps, default is 0.
</p></dd>
<dt><samp>txt_chop_spaces</samp></dt>
<dd><p>Chops leading and trailing spaces and removes empty lines from the generated
text. This option is useful for teletext based subtitles where empty spaces may
be present at the start or at the end of the lines or empty lines may be
present between the subtitle lines because of double-sized teletext charactes.
Default value is 1.
</p></dd>
<dt><samp>txt_duration</samp></dt>
<dd><p>Sets the display duration of the decoded teletext pages or subtitles in
miliseconds. Default value is 30000 which is 30 seconds.
</p></dd>
<dt><samp>txt_transparent</samp></dt>
<dd><p>Force transparent background of the generated teletext bitmaps. Default value
is 0 which means an opaque (black) background.
</p></dd>
</dl>
<a name="Encoders"></a>
<h2 class="chapter">15 Encoders<span class="pull-right"><a class="anchor hidden-xs" href="#Encoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Encoders" aria-hidden="true">TOC</a></span></h2>
<p>Encoders are configured elements in FFmpeg which allow the encoding of
multimedia streams.
</p>
<p>When you configure your FFmpeg build, all the supported native encoders
are enabled by default. Encoders requiring an external library must be enabled
manually via the corresponding <code>--enable-lib</code> option. You can list all
available encoders using the configure option <code>--list-encoders</code>.
</p>
<p>You can disable all the encoders with the configure option
<code>--disable-encoders</code> and selectively enable / disable single encoders
with the options <code>--enable-encoder=<var>ENCODER</var></code> /
<code>--disable-encoder=<var>ENCODER</var></code>.
</p>
<p>The option <code>-encoders</code> of the ff* tools will display the list of
enabled encoders.
</p>
<a name="Audio-Encoders"></a>
<h2 class="chapter">16 Audio Encoders<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Encoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Encoders" aria-hidden="true">TOC</a></span></h2>
<p>A description of some of the currently available audio encoders
follows.
</p>
<a name="aacenc"></a><a name="aac"></a>
<h3 class="section">16.1 aac<span class="pull-right"><a class="anchor hidden-xs" href="#aac" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aac" aria-hidden="true">TOC</a></span></h3>
<p>Advanced Audio Coding (AAC) encoder.
</p>
<p>This encoder is an experimental FFmpeg-native AAC encoder. Currently only the
low complexity (AAC-LC) profile is supported. To use this encoder, you must set
<samp>strict</samp> option to ‘<samp>experimental</samp>’ or lower.
</p>
<p>As this encoder is experimental, unexpected behavior may exist from time to
time. For a more stable AAC encoder, see <a href="#libvo_002daacenc">libvo-aacenc</a>. However, be warned
that it has a worse quality reported by some users.
</p>
<p>See also <a href="#libfdk_002daac_002denc">libfdk_aac</a> and <a href="#libfaac">libfaac</a>.
</p>
<a name="Options-6"></a>
<h4 class="subsection">16.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-6" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-6" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set bit rate in bits/s. Setting this automatically activates constant bit rate
(CBR) mode.
</p>
</dd>
<dt><samp>q</samp></dt>
<dd><p>Set quality for variable bit rate (VBR) mode. This option is valid only using
the <code>ffmpeg</code> command-line tool. For library interface users, use
<samp>global_quality</samp>.
</p>
</dd>
<dt><samp>stereo_mode</samp></dt>
<dd><p>Set stereo encoding mode. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Automatically selected by the encoder.
</p>
</dd>
<dt>‘<samp>ms_off</samp>’</dt>
<dd><p>Disable middle/side encoding. This is the default.
</p>
</dd>
<dt>‘<samp>ms_force</samp>’</dt>
<dd><p>Force middle/side encoding.
</p></dd>
</dl>
</dd>
<dt><samp>aac_coder</samp></dt>
<dd><p>Set AAC encoder coding method. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>faac</samp>’</dt>
<dd><p>FAAC-inspired method.
</p>
<p>This method is a simplified reimplementation of the method used in FAAC, which
sets thresholds proportional to the band energies, and then decreases all the
thresholds with quantizer steps to find the appropriate quantization with
distortion below threshold band by band.
</p>
<p>The quality of this method is comparable to the two loop searching method
described below, but somewhat a little better and slower.
</p>
</dd>
<dt>‘<samp>anmr</samp>’</dt>
<dd><p>Average noise to mask ratio (ANMR) trellis-based solution.
</p>
<p>This has a theoretic best quality out of all the coding methods, but at the
cost of the slowest speed.
</p>
</dd>
<dt>‘<samp>twoloop</samp>’</dt>
<dd><p>Two loop searching (TLS) method.
</p>
<p>This method first sets quantizers depending on band thresholds and then tries
to find an optimal combination by adding or subtracting a specific value from
all quantizers and adjusting some individual quantizer a little.
</p>
<p>This method produces similar quality with the FAAC method and is the default.
</p>
</dd>
<dt>‘<samp>fast</samp>’</dt>
<dd><p>Constant quantizer method.
</p>
<p>This method sets a constant quantizer for all bands. This is the fastest of all
the methods, yet produces the worst quality.
</p>
</dd>
</dl>
</dd>
</dl>
<a name="ac3-and-ac3_005ffixed"></a>
<h3 class="section">16.2 ac3 and ac3_fixed<span class="pull-right"><a class="anchor hidden-xs" href="#ac3-and-ac3_005ffixed" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ac3-and-ac3_005ffixed" aria-hidden="true">TOC</a></span></h3>
<p>AC-3 audio encoders.
</p>
<p>These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
the undocumented RealAudio 3 (a.k.a. dnet).
</p>
<p>The <var>ac3</var> encoder uses floating-point math, while the <var>ac3_fixed</var>
encoder only uses fixed-point integer math. This does not mean that one is
always faster, just that one or the other may be better suited to a
particular system. The floating-point encoder will generally produce better
quality audio for a given bitrate. The <var>ac3_fixed</var> encoder is not the
default codec for any of the output formats, so it must be specified explicitly
using the option <code>-acodec ac3_fixed</code> in order to use it.
</p>
<a name="AC_002d3-Metadata"></a>
<h4 class="subsection">16.2.1 AC-3 Metadata<span class="pull-right"><a class="anchor hidden-xs" href="#AC_002d3-Metadata" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-AC_002d3-Metadata" aria-hidden="true">TOC</a></span></h4>
<p>The AC-3 metadata options are used to set parameters that describe the audio,
but in most cases do not affect the audio encoding itself. Some of the options
do directly affect or influence the decoding and playback of the resulting
bitstream, while others are just for informational purposes. A few of the
options will add bits to the output stream that could otherwise be used for
audio data, and will thus affect the quality of the output. Those will be
indicated accordingly with a note in the option list below.
</p>
<p>These parameters are described in detail in several publicly-available
documents.
</p><ul>
<li> <a href="http://www.atsc.org/cms/standards/a_52-2010.pdf">A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard</a>
</li><li> <a href="http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf">A/54 - Guide to the Use of the ATSC Digital Television Standard</a>
</li><li> <a href="http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf">Dolby Metadata Guide</a>
</li><li> <a href="http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf">Dolby Digital Professional Encoding Guidelines</a>
</li></ul>
<a name="Metadata-Control-Options"></a>
<h4 class="subsubsection">16.2.1.1 Metadata Control Options<span class="pull-right"><a class="anchor hidden-xs" href="#Metadata-Control-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Metadata-Control-Options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-per_frame_metadata <var>boolean</var></samp></dt>
<dd><p>Allow Per-Frame Metadata. Specifies if the encoder should check for changing
metadata for each frame.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dd><p>The metadata values set at initialization will be used for every frame in the
stream. (default)
</p></dd>
<dt><samp>1</samp></dt>
<dd><p>Metadata values can be changed before encoding each frame.
</p></dd>
</dl>
</dd>
</dl>
<a name="Downmix-Levels"></a>
<h4 class="subsubsection">16.2.1.2 Downmix Levels<span class="pull-right"><a class="anchor hidden-xs" href="#Downmix-Levels" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Downmix-Levels" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-center_mixlev <var>level</var></samp></dt>
<dd><p>Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo. This field will only be written to the
bitstream if a center channel is present. The value is specified as a scale
factor. There are 3 valid values:
</p><dl compact="compact">
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3dB gain
</p></dd>
<dt><samp>0.595</samp></dt>
<dd><p>Apply -4.5dB gain (default)
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6dB gain
</p></dd>
</dl>
</dd>
<dt><samp>-surround_mixlev <var>level</var></samp></dt>
<dd><p>Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo. This field will only be written to the
bitstream if one or more surround channels are present. The value is specified
as a scale factor. There are 3 valid values:
</p><dl compact="compact">
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3dB gain
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6dB gain (default)
</p></dd>
<dt><samp>0.000</samp></dt>
<dd><p>Silence Surround Channel(s)
</p></dd>
</dl>
</dd>
</dl>
<a name="Audio-Production-Information"></a>
<h4 class="subsubsection">16.2.1.3 Audio Production Information<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Production-Information" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Production-Information" aria-hidden="true">TOC</a></span></h4>
<p>Audio Production Information is optional information describing the mixing
environment. Either none or both of the fields are written to the bitstream.
</p>
<dl compact="compact">
<dt><samp>-mixing_level <var>number</var></samp></dt>
<dd><p>Mixing Level. Specifies peak sound pressure level (SPL) in the production
environment when the mix was mastered. Valid values are 80 to 111, or -1 for
unknown or not indicated. The default value is -1, but that value cannot be
used if the Audio Production Information is written to the bitstream. Therefore,
if the <code>room_type</code> option is not the default value, the <code>mixing_level</code>
option must not be -1.
</p>
</dd>
<dt><samp>-room_type <var>type</var></samp></dt>
<dd><p>Room Type. Describes the equalization used during the final mixing session at
the studio or on the dubbing stage. A large room is a dubbing stage with the
industry standard X-curve equalization; a small room has flat equalization.
This field will not be written to the bitstream if both the <code>mixing_level</code>
option and the <code>room_type</code> option have the default values.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>notindicated</samp></dt>
<dd><p>Not Indicated (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>large</samp></dt>
<dd><p>Large Room
</p></dd>
<dt><samp>2</samp></dt>
<dt><samp>small</samp></dt>
<dd><p>Small Room
</p></dd>
</dl>
</dd>
</dl>
<a name="Other-Metadata-Options"></a>
<h4 class="subsubsection">16.2.1.4 Other Metadata Options<span class="pull-right"><a class="anchor hidden-xs" href="#Other-Metadata-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Other-Metadata-Options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-copyright <var>boolean</var></samp></dt>
<dd><p>Copyright Indicator. Specifies whether a copyright exists for this audio.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>No Copyright Exists (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Copyright Exists
</p></dd>
</dl>
</dd>
<dt><samp>-dialnorm <var>value</var></samp></dt>
<dd><p>Dialogue Normalization. Indicates how far the average dialogue level of the
program is below digital 100% full scale (0 dBFS). This parameter determines a
level shift during audio reproduction that sets the average volume of the
dialogue to a preset level. The goal is to match volume level between program
sources. A value of -31dB will result in no volume level change, relative to
the source volume, during audio reproduction. Valid values are whole numbers in
the range -31 to -1, with -31 being the default.
</p>
</dd>
<dt><samp>-dsur_mode <var>mode</var></samp></dt>
<dd><p>Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
(Pro Logic). This field will only be written to the bitstream if the audio
stream is stereo. Using this option does <b>NOT</b> mean the encoder will actually
apply Dolby Surround processing.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>notindicated</samp></dt>
<dd><p>Not Indicated (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>Not Dolby Surround Encoded
</p></dd>
<dt><samp>2</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Dolby Surround Encoded
</p></dd>
</dl>
</dd>
<dt><samp>-original <var>boolean</var></samp></dt>
<dd><p>Original Bit Stream Indicator. Specifies whether this audio is from the
original source and not a copy.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>Not Original Source
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Original Source (default)
</p></dd>
</dl>
</dd>
</dl>
<a name="Extended-Bitstream-Information"></a>
<h4 class="subsection">16.2.2 Extended Bitstream Information<span class="pull-right"><a class="anchor hidden-xs" href="#Extended-Bitstream-Information" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Extended-Bitstream-Information" aria-hidden="true">TOC</a></span></h4>
<p>The extended bitstream options are part of the Alternate Bit Stream Syntax as
specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
If any one parameter in a group is specified, all values in that group will be
written to the bitstream. Default values are used for those that are written
but have not been specified. If the mixing levels are written, the decoder
will use these values instead of the ones specified in the <code>center_mixlev</code>
and <code>surround_mixlev</code> options if it supports the Alternate Bit Stream
Syntax.
</p>
<a name="Extended-Bitstream-Information-_002d-Part-1"></a>
<h4 class="subsubsection">16.2.2.1 Extended Bitstream Information - Part 1<span class="pull-right"><a class="anchor hidden-xs" href="#Extended-Bitstream-Information-_002d-Part-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Extended-Bitstream-Information-_002d-Part-1" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-dmix_mode <var>mode</var></samp></dt>
<dd><p>Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>notindicated</samp></dt>
<dd><p>Not Indicated (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>ltrt</samp></dt>
<dd><p>Lt/Rt Downmix Preferred
</p></dd>
<dt><samp>2</samp></dt>
<dt><samp>loro</samp></dt>
<dd><p>Lo/Ro Downmix Preferred
</p></dd>
</dl>
</dd>
<dt><samp>-ltrt_cmixlev <var>level</var></samp></dt>
<dd><p>Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
center channel when downmixing to stereo in Lt/Rt mode.
</p><dl compact="compact">
<dt><samp>1.414</samp></dt>
<dd><p>Apply +3dB gain
</p></dd>
<dt><samp>1.189</samp></dt>
<dd><p>Apply +1.5dB gain
</p></dd>
<dt><samp>1.000</samp></dt>
<dd><p>Apply 0dB gain
</p></dd>
<dt><samp>0.841</samp></dt>
<dd><p>Apply -1.5dB gain
</p></dd>
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3.0dB gain
</p></dd>
<dt><samp>0.595</samp></dt>
<dd><p>Apply -4.5dB gain (default)
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6.0dB gain
</p></dd>
<dt><samp>0.000</samp></dt>
<dd><p>Silence Center Channel
</p></dd>
</dl>
</dd>
<dt><samp>-ltrt_surmixlev <var>level</var></samp></dt>
<dd><p>Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
surround channel(s) when downmixing to stereo in Lt/Rt mode.
</p><dl compact="compact">
<dt><samp>0.841</samp></dt>
<dd><p>Apply -1.5dB gain
</p></dd>
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3.0dB gain
</p></dd>
<dt><samp>0.595</samp></dt>
<dd><p>Apply -4.5dB gain
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6.0dB gain (default)
</p></dd>
<dt><samp>0.000</samp></dt>
<dd><p>Silence Surround Channel(s)
</p></dd>
</dl>
</dd>
<dt><samp>-loro_cmixlev <var>level</var></samp></dt>
<dd><p>Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
center channel when downmixing to stereo in Lo/Ro mode.
</p><dl compact="compact">
<dt><samp>1.414</samp></dt>
<dd><p>Apply +3dB gain
</p></dd>
<dt><samp>1.189</samp></dt>
<dd><p>Apply +1.5dB gain
</p></dd>
<dt><samp>1.000</samp></dt>
<dd><p>Apply 0dB gain
</p></dd>
<dt><samp>0.841</samp></dt>
<dd><p>Apply -1.5dB gain
</p></dd>
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3.0dB gain
</p></dd>
<dt><samp>0.595</samp></dt>
<dd><p>Apply -4.5dB gain (default)
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6.0dB gain
</p></dd>
<dt><samp>0.000</samp></dt>
<dd><p>Silence Center Channel
</p></dd>
</dl>
</dd>
<dt><samp>-loro_surmixlev <var>level</var></samp></dt>
<dd><p>Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
surround channel(s) when downmixing to stereo in Lo/Ro mode.
</p><dl compact="compact">
<dt><samp>0.841</samp></dt>
<dd><p>Apply -1.5dB gain
</p></dd>
<dt><samp>0.707</samp></dt>
<dd><p>Apply -3.0dB gain
</p></dd>
<dt><samp>0.595</samp></dt>
<dd><p>Apply -4.5dB gain
</p></dd>
<dt><samp>0.500</samp></dt>
<dd><p>Apply -6.0dB gain (default)
</p></dd>
<dt><samp>0.000</samp></dt>
<dd><p>Silence Surround Channel(s)
</p></dd>
</dl>
</dd>
</dl>
<a name="Extended-Bitstream-Information-_002d-Part-2"></a>
<h4 class="subsubsection">16.2.2.2 Extended Bitstream Information - Part 2<span class="pull-right"><a class="anchor hidden-xs" href="#Extended-Bitstream-Information-_002d-Part-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Extended-Bitstream-Information-_002d-Part-2" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-dsurex_mode <var>mode</var></samp></dt>
<dd><p>Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
(7.1 matrixed to 5.1). Using this option does <b>NOT</b> mean the encoder will actually
apply Dolby Surround EX processing.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>notindicated</samp></dt>
<dd><p>Not Indicated (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Dolby Surround EX Off
</p></dd>
<dt><samp>2</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>Dolby Surround EX On
</p></dd>
</dl>
</dd>
<dt><samp>-dheadphone_mode <var>mode</var></samp></dt>
<dd><p>Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
option does <b>NOT</b> mean the encoder will actually apply Dolby Headphone
processing.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>notindicated</samp></dt>
<dd><p>Not Indicated (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Dolby Headphone Off
</p></dd>
<dt><samp>2</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>Dolby Headphone On
</p></dd>
</dl>
</dd>
<dt><samp>-ad_conv_type <var>type</var></samp></dt>
<dd><p>A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
conversion.
</p><dl compact="compact">
<dt><samp>0</samp></dt>
<dt><samp>standard</samp></dt>
<dd><p>Standard A/D Converter (default)
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>hdcd</samp></dt>
<dd><p>HDCD A/D Converter
</p></dd>
</dl>
</dd>
</dl>
<a name="Other-AC_002d3-Encoding-Options"></a>
<h4 class="subsection">16.2.3 Other AC-3 Encoding Options<span class="pull-right"><a class="anchor hidden-xs" href="#Other-AC_002d3-Encoding-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Other-AC_002d3-Encoding-Options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-stereo_rematrixing <var>boolean</var></samp></dt>
<dd><p>Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
is an optional AC-3 feature that increases quality by selectively encoding
the left/right channels as mid/side. This option is enabled by default, and it
is highly recommended that it be left as enabled except for testing purposes.
</p>
</dd>
</dl>
<a name="Floating_002dPoint_002dOnly-AC_002d3-Encoding-Options"></a>
<h4 class="subsection">16.2.4 Floating-Point-Only AC-3 Encoding Options<span class="pull-right"><a class="anchor hidden-xs" href="#Floating_002dPoint_002dOnly-AC_002d3-Encoding-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Floating_002dPoint_002dOnly-AC_002d3-Encoding-Options" aria-hidden="true">TOC</a></span></h4>
<p>These options are only valid for the floating-point encoder and do not exist
for the fixed-point encoder due to the corresponding features not being
implemented in fixed-point.
</p>
<dl compact="compact">
<dt><samp>-channel_coupling <var>boolean</var></samp></dt>
<dd><p>Enables/Disables use of channel coupling, which is an optional AC-3 feature
that increases quality by combining high frequency information from multiple
channels into a single channel. The per-channel high frequency information is
sent with less accuracy in both the frequency and time domains. This allows
more bits to be used for lower frequencies while preserving enough information
to reconstruct the high frequencies. This option is enabled by default for the
floating-point encoder and should generally be left as enabled except for
testing purposes or to increase encoding speed.
</p><dl compact="compact">
<dt><samp>-1</samp></dt>
<dt><samp>auto</samp></dt>
<dd><p>Selected by Encoder (default)
</p></dd>
<dt><samp>0</samp></dt>
<dt><samp>off</samp></dt>
<dd><p>Disable Channel Coupling
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>on</samp></dt>
<dd><p>Enable Channel Coupling
</p></dd>
</dl>
</dd>
<dt><samp>-cpl_start_band <var>number</var></samp></dt>
<dd><p>Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
value higher than the bandwidth is used, it will be reduced to 1 less than the
coupling end band. If <var>auto</var> is used, the start band will be determined by
the encoder based on the bit rate, sample rate, and channel layout. This option
has no effect if channel coupling is disabled.
</p><dl compact="compact">
<dt><samp>-1</samp></dt>
<dt><samp>auto</samp></dt>
<dd><p>Selected by Encoder (default)
</p></dd>
</dl>
</dd>
</dl>
<a name="flac"></a><a name="flac-2"></a>
<h3 class="section">16.3 flac<span class="pull-right"><a class="anchor hidden-xs" href="#flac-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-flac-2" aria-hidden="true">TOC</a></span></h3>
<p>FLAC (Free Lossless Audio Codec) Encoder
</p>
<a name="Options-7"></a>
<h4 class="subsection">16.3.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-7" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-7" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by FFmpeg’s flac encoder.
</p>
<dl compact="compact">
<dt><samp>compression_level</samp></dt>
<dd><p>Sets the compression level, which chooses defaults for many other options
if they are not set explicitly.
</p>
</dd>
<dt><samp>frame_size</samp></dt>
<dd><p>Sets the size of the frames in samples per channel.
</p>
</dd>
<dt><samp>lpc_coeff_precision</samp></dt>
<dd><p>Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the
default.
</p>
</dd>
<dt><samp>lpc_type</samp></dt>
<dd><p>Sets the first stage LPC algorithm
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>LPC is not used
</p>
</dd>
<dt>‘<samp>fixed</samp>’</dt>
<dd><p>fixed LPC coefficients
</p>
</dd>
<dt>‘<samp>levinson</samp>’</dt>
<dt>‘<samp>cholesky</samp>’</dt>
</dl>
</dd>
<dt><samp>lpc_passes</samp></dt>
<dd><p>Number of passes to use for Cholesky factorization during LPC analysis
</p>
</dd>
<dt><samp>min_partition_order</samp></dt>
<dd><p>The minimum partition order
</p>
</dd>
<dt><samp>max_partition_order</samp></dt>
<dd><p>The maximum partition order
</p>
</dd>
<dt><samp>prediction_order_method</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>estimation</samp>’</dt>
<dt>‘<samp>2level</samp>’</dt>
<dt>‘<samp>4level</samp>’</dt>
<dt>‘<samp>8level</samp>’</dt>
<dt>‘<samp>search</samp>’</dt>
<dd><p>Bruteforce search
</p></dd>
<dt>‘<samp>log</samp>’</dt>
</dl>
</dd>
<dt><samp>ch_mode</samp></dt>
<dd><p>Channel mode
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>The mode is chosen automatically for each frame
</p></dd>
<dt>‘<samp>indep</samp>’</dt>
<dd><p>Chanels are independently coded
</p></dd>
<dt>‘<samp>left_side</samp>’</dt>
<dt>‘<samp>right_side</samp>’</dt>
<dt>‘<samp>mid_side</samp>’</dt>
</dl>
</dd>
<dt><samp>exact_rice_parameters</samp></dt>
<dd><p>Chooses if rice parameters are calculated exactly or approximately.
if set to 1 then they are chosen exactly, which slows the code down slightly and
improves compression slightly.
</p>
</dd>
<dt><samp>multi_dim_quant</samp></dt>
<dd><p>Multi Dimensional Quantization. If set to 1 then a 2nd stage LPC algorithm is
applied after the first stage to finetune the coefficients. This is quite slow
and slightly improves compression.
</p>
</dd>
</dl>
<a name="libfaac"></a><a name="libfaac-1"></a>
<h3 class="section">16.4 libfaac<span class="pull-right"><a class="anchor hidden-xs" href="#libfaac-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libfaac-1" aria-hidden="true">TOC</a></span></h3>
<p>libfaac AAC (Advanced Audio Coding) encoder wrapper.
</p>
<p>Requires the presence of the libfaac headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libfaac --enable-nonfree</code>.
</p>
<p>This encoder is considered to be of higher quality with respect to the
<a href="#aacenc">the native experimental FFmpeg AAC encoder</a>.
</p>
<p>For more information see the libfaac project at
<a href="http://www.audiocoding.com/faac.html/">http://www.audiocoding.com/faac.html/</a>.
</p>
<a name="Options-8"></a>
<h4 class="subsection">16.4.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-8" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-8" aria-hidden="true">TOC</a></span></h4>
<p>The following shared FFmpeg codec options are recognized.
</p>
<p>The following options are supported by the libfaac wrapper. The
<code>faac</code>-equivalent of the options are listed in parentheses.
</p>
<dl compact="compact">
<dt><samp>b (<em>-b</em>)</samp></dt>
<dd><p>Set bit rate in bits/s for ABR (Average Bit Rate) mode. If the bit rate
is not explicitly specified, it is automatically set to a suitable
value depending on the selected profile. <code>faac</code> bitrate is
expressed in kilobits/s.
</p>
<p>Note that libfaac does not support CBR (Constant Bit Rate) but only
ABR (Average Bit Rate).
</p>
<p>If VBR mode is enabled this option is ignored.
</p>
</dd>
<dt><samp>ar (<em>-R</em>)</samp></dt>
<dd><p>Set audio sampling rate (in Hz).
</p>
</dd>
<dt><samp>ac (<em>-c</em>)</samp></dt>
<dd><p>Set the number of audio channels.
</p>
</dd>
<dt><samp>cutoff (<em>-C</em>)</samp></dt>
<dd><p>Set cutoff frequency. If not specified (or explicitly set to 0) it
will use a value automatically computed by the library. Default value
is 0.
</p>
</dd>
<dt><samp>profile</samp></dt>
<dd><p>Set audio profile.
</p>
<p>The following profiles are recognized:
</p><dl compact="compact">
<dt>‘<samp>aac_main</samp>’</dt>
<dd><p>Main AAC (Main)
</p>
</dd>
<dt>‘<samp>aac_low</samp>’</dt>
<dd><p>Low Complexity AAC (LC)
</p>
</dd>
<dt>‘<samp>aac_ssr</samp>’</dt>
<dd><p>Scalable Sample Rate (SSR)
</p>
</dd>
<dt>‘<samp>aac_ltp</samp>’</dt>
<dd><p>Long Term Prediction (LTP)
</p></dd>
</dl>
<p>If not specified it is set to ‘<samp>aac_low</samp>’.
</p>
</dd>
<dt><samp>flags +qscale</samp></dt>
<dd><p>Set constant quality VBR (Variable Bit Rate) mode.
</p>
</dd>
<dt><samp>global_quality</samp></dt>
<dd><p>Set quality in VBR mode as an integer number of lambda units.
</p>
<p>Only relevant when VBR mode is enabled with <code>flags +qscale</code>. The
value is converted to QP units by dividing it by <code>FF_QP2LAMBDA</code>,
and used to set the quality value used by libfaac. A reasonable range
for the option value in QP units is [10-500], the higher the value the
higher the quality.
</p>
</dd>
<dt><samp>q (<em>-q</em>)</samp></dt>
<dd><p>Enable VBR mode when set to a non-negative value, and set constant
quality value as a double floating point value in QP units.
</p>
<p>The value sets the quality value used by libfaac. A reasonable range
for the option value is [10-500], the higher the value the higher the
quality.
</p>
<p>This option is valid only using the <code>ffmpeg</code> command-line
tool. For library interface users, use <samp>global_quality</samp>.
</p></dd>
</dl>
<a name="Examples-2"></a>
<h4 class="subsection">16.4.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-2" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use <code>ffmpeg</code> to convert an audio file to ABR 128 kbps AAC in an M4A (MP4)
container:
<div class="example">
<pre class="example">ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a
</pre></div>
</li><li> Use <code>ffmpeg</code> to convert an audio file to VBR AAC, using the
LTP AAC profile:
<div class="example">
<pre class="example">ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a
</pre></div>
</li></ul>
<a name="libfdk_002daac_002denc"></a><a name="libfdk_005faac"></a>
<h3 class="section">16.5 libfdk_aac<span class="pull-right"><a class="anchor hidden-xs" href="#libfdk_005faac" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libfdk_005faac" aria-hidden="true">TOC</a></span></h3>
<p>libfdk-aac AAC (Advanced Audio Coding) encoder wrapper.
</p>
<p>The libfdk-aac library is based on the Fraunhofer FDK AAC code from
the Android project.
</p>
<p>Requires the presence of the libfdk-aac headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libfdk-aac</code>. The library is also incompatible with GPL,
so if you allow the use of GPL, you should configure with
<code>--enable-gpl --enable-nonfree --enable-libfdk-aac</code>.
</p>
<p>This encoder is considered to be of higher quality with respect to
both <a href="#aacenc">the native experimental FFmpeg AAC encoder</a> and
<a href="#libfaac">libfaac</a>.
</p>
<p>VBR encoding, enabled through the <samp>vbr</samp> or <samp>flags
+qscale</samp> options, is experimental and only works with some
combinations of parameters.
</p>
<p>Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or
higher.
</p>
<p>For more information see the fdk-aac project at
<a href="http://sourceforge.net/p/opencore-amr/fdk-aac/">http://sourceforge.net/p/opencore-amr/fdk-aac/</a>.
</p>
<a name="Options-9"></a>
<h4 class="subsection">16.5.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-9" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-9" aria-hidden="true">TOC</a></span></h4>
<p>The following options are mapped on the shared FFmpeg codec options.
</p>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set bit rate in bits/s. If the bitrate is not explicitly specified, it
is automatically set to a suitable value depending on the selected
profile.
</p>
<p>In case VBR mode is enabled the option is ignored.
</p>
</dd>
<dt><samp>ar</samp></dt>
<dd><p>Set audio sampling rate (in Hz).
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Set the number of audio channels.
</p>
</dd>
<dt><samp>flags +qscale</samp></dt>
<dd><p>Enable fixed quality, VBR (Variable Bit Rate) mode.
Note that VBR is implicitly enabled when the <samp>vbr</samp> value is
positive.
</p>
</dd>
<dt><samp>cutoff</samp></dt>
<dd><p>Set cutoff frequency. If not specified (or explicitly set to 0) it
will use a value automatically computed by the library. Default value
is 0.
</p>
</dd>
<dt><samp>profile</samp></dt>
<dd><p>Set audio profile.
</p>
<p>The following profiles are recognized:
</p><dl compact="compact">
<dt>‘<samp>aac_low</samp>’</dt>
<dd><p>Low Complexity AAC (LC)
</p>
</dd>
<dt>‘<samp>aac_he</samp>’</dt>
<dd><p>High Efficiency AAC (HE-AAC)
</p>
</dd>
<dt>‘<samp>aac_he_v2</samp>’</dt>
<dd><p>High Efficiency AAC version 2 (HE-AACv2)
</p>
</dd>
<dt>‘<samp>aac_ld</samp>’</dt>
<dd><p>Low Delay AAC (LD)
</p>
</dd>
<dt>‘<samp>aac_eld</samp>’</dt>
<dd><p>Enhanced Low Delay AAC (ELD)
</p></dd>
</dl>
<p>If not specified it is set to ‘<samp>aac_low</samp>’.
</p></dd>
</dl>
<p>The following are private options of the libfdk_aac encoder.
</p>
<dl compact="compact">
<dt><samp>afterburner</samp></dt>
<dd><p>Enable afterburner feature if set to 1, disabled if set to 0. This
improves the quality but also the required processing power.
</p>
<p>Default value is 1.
</p>
</dd>
<dt><samp>eld_sbr</samp></dt>
<dd><p>Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled
if set to 0.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>signaling</samp></dt>
<dd><p>Set SBR/PS signaling style.
</p>
<p>It can assume one of the following values:
</p><dl compact="compact">
<dt>‘<samp>default</samp>’</dt>
<dd><p>choose signaling implicitly (explicit hierarchical by default,
implicit if global header is disabled)
</p>
</dd>
<dt>‘<samp>implicit</samp>’</dt>
<dd><p>implicit backwards compatible signaling
</p>
</dd>
<dt>‘<samp>explicit_sbr</samp>’</dt>
<dd><p>explicit SBR, implicit PS signaling
</p>
</dd>
<dt>‘<samp>explicit_hierarchical</samp>’</dt>
<dd><p>explicit hierarchical signaling
</p></dd>
</dl>
<p>Default value is ‘<samp>default</samp>’.
</p>
</dd>
<dt><samp>latm</samp></dt>
<dd><p>Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>header_period</samp></dt>
<dd><p>Set StreamMuxConfig and PCE repetition period (in frames) for sending
in-band configuration buffers within LATM/LOAS transport layer.
</p>
<p>Must be a 16-bits non-negative integer.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>vbr</samp></dt>
<dd><p>Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty
good) and 5 is highest quality. A value of 0 will disable VBR, and CBR
(Constant Bit Rate) is enabled.
</p>
<p>Currently only the ‘<samp>aac_low</samp>’ profile supports VBR encoding.
</p>
<p>VBR modes 1-5 correspond to roughly the following average bit rates:
</p>
<dl compact="compact">
<dt>‘<samp>1</samp>’</dt>
<dd><p>32 kbps/channel
</p></dd>
<dt>‘<samp>2</samp>’</dt>
<dd><p>40 kbps/channel
</p></dd>
<dt>‘<samp>3</samp>’</dt>
<dd><p>48-56 kbps/channel
</p></dd>
<dt>‘<samp>4</samp>’</dt>
<dd><p>64 kbps/channel
</p></dd>
<dt>‘<samp>5</samp>’</dt>
<dd><p>about 80-96 kbps/channel
</p></dd>
</dl>
<p>Default value is 0.
</p></dd>
</dl>
<a name="Examples-3"></a>
<h4 class="subsection">16.5.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-3" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use <code>ffmpeg</code> to convert an audio file to VBR AAC in an M4A (MP4)
container:
<div class="example">
<pre class="example">ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a
</pre></div>
</li><li> Use <code>ffmpeg</code> to convert an audio file to CBR 64k kbps AAC, using the
High-Efficiency AAC profile:
<div class="example">
<pre class="example">ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a
</pre></div>
</li></ul>
<a name="libmp3lame"></a><a name="libmp3lame-1"></a>
<h3 class="section">16.6 libmp3lame<span class="pull-right"><a class="anchor hidden-xs" href="#libmp3lame-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libmp3lame-1" aria-hidden="true">TOC</a></span></h3>
<p>LAME (Lame Ain’t an MP3 Encoder) MP3 encoder wrapper.
</p>
<p>Requires the presence of the libmp3lame headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libmp3lame</code>.
</p>
<p>See <a href="#libshine">libshine</a> for a fixed-point MP3 encoder, although with a
lower quality.
</p>
<a name="Options-10"></a>
<h4 class="subsection">16.6.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-10" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-10" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libmp3lame wrapper. The
<code>lame</code>-equivalent of the options are listed in parentheses.
</p>
<dl compact="compact">
<dt><samp>b (<em>-b</em>)</samp></dt>
<dd><p>Set bitrate expressed in bits/s for CBR or ABR. LAME <code>bitrate</code> is
expressed in kilobits/s.
</p>
</dd>
<dt><samp>q (<em>-V</em>)</samp></dt>
<dd><p>Set constant quality setting for VBR. This option is valid only
using the <code>ffmpeg</code> command-line tool. For library interface
users, use <samp>global_quality</samp>.
</p>
</dd>
<dt><samp>compression_level (<em>-q</em>)</samp></dt>
<dd><p>Set algorithm quality. Valid arguments are integers in the 0-9 range,
with 0 meaning highest quality but slowest, and 9 meaning fastest
while producing the worst quality.
</p>
</dd>
<dt><samp>reservoir</samp></dt>
<dd><p>Enable use of bit reservoir when set to 1. Default value is 1. LAME
has this enabled by default, but can be overridden by use
<samp>--nores</samp> option.
</p>
</dd>
<dt><samp>joint_stereo (<em>-m j</em>)</samp></dt>
<dd><p>Enable the encoder to use (on a frame by frame basis) either L/R
stereo or mid/side stereo. Default value is 1.
</p>
</dd>
<dt><samp>abr (<em>--abr</em>)</samp></dt>
<dd><p>Enable the encoder to use ABR when set to 1. The <code>lame</code>
<samp>--abr</samp> sets the target bitrate, while this options only
tells FFmpeg to use ABR still relies on <samp>b</samp> to set bitrate.
</p>
</dd>
</dl>
<a name="libopencore_002damrnb-1"></a>
<h3 class="section">16.7 libopencore-amrnb<span class="pull-right"><a class="anchor hidden-xs" href="#libopencore_002damrnb-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libopencore_002damrnb-1" aria-hidden="true">TOC</a></span></h3>
<p>OpenCORE Adaptive Multi-Rate Narrowband encoder.
</p>
<p>Requires the presence of the libopencore-amrnb headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libopencore-amrnb --enable-version3</code>.
</p>
<p>This is a mono-only encoder. Officially it only supports 8000Hz sample rate,
but you can override it by setting <samp>strict</samp> to ‘<samp>unofficial</samp>’ or
lower.
</p>
<a name="Options-11"></a>
<h4 class="subsection">16.7.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-11" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-11" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set bitrate in bits per second. Only the following bitrates are supported,
otherwise libavcodec will round to the nearest valid bitrate.
</p>
<dl compact="compact">
<dt><samp>4750</samp></dt>
<dt><samp>5150</samp></dt>
<dt><samp>5900</samp></dt>
<dt><samp>6700</samp></dt>
<dt><samp>7400</samp></dt>
<dt><samp>7950</samp></dt>
<dt><samp>10200</samp></dt>
<dt><samp>12200</samp></dt>
</dl>
</dd>
<dt><samp>dtx</samp></dt>
<dd><p>Allow discontinuous transmission (generate comfort noise) when set to 1. The
default value is 0 (disabled).
</p>
</dd>
</dl>
<a name="libshine"></a><a name="libshine-1"></a>
<h3 class="section">16.8 libshine<span class="pull-right"><a class="anchor hidden-xs" href="#libshine-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libshine-1" aria-hidden="true">TOC</a></span></h3>
<p>Shine Fixed-Point MP3 encoder wrapper.
</p>
<p>Shine is a fixed-point MP3 encoder. It has a far better performance on
platforms without an FPU, e.g. armel CPUs, and some phones and tablets.
However, as it is more targeted on performance than quality, it is not on par
with LAME and other production-grade encoders quality-wise. Also, according to
the project’s homepage, this encoder may not be free of bugs as the code was
written a long time ago and the project was dead for at least 5 years.
</p>
<p>This encoder only supports stereo and mono input. This is also CBR-only.
</p>
<p>The original project (last updated in early 2007) is at
<a href="http://sourceforge.net/projects/libshine-fxp/">http://sourceforge.net/projects/libshine-fxp/</a>. We only support the
updated fork by the Savonet/Liquidsoap project at <a href="https://github.com/savonet/shine">https://github.com/savonet/shine</a>.
</p>
<p>Requires the presence of the libshine headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libshine</code>.
</p>
<p>See also <a href="#libmp3lame">libmp3lame</a>.
</p>
<a name="Options-12"></a>
<h4 class="subsection">16.8.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-12" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-12" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libshine wrapper. The
<code>shineenc</code>-equivalent of the options are listed in parentheses.
</p>
<dl compact="compact">
<dt><samp>b (<em>-b</em>)</samp></dt>
<dd><p>Set bitrate expressed in bits/s for CBR. <code>shineenc</code> <samp>-b</samp> option
is expressed in kilobits/s.
</p>
</dd>
</dl>
<a name="libtwolame"></a>
<h3 class="section">16.9 libtwolame<span class="pull-right"><a class="anchor hidden-xs" href="#libtwolame" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libtwolame" aria-hidden="true">TOC</a></span></h3>
<p>TwoLAME MP2 encoder wrapper.
</p>
<p>Requires the presence of the libtwolame headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libtwolame</code>.
</p>
<a name="Options-13"></a>
<h4 class="subsection">16.9.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-13" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-13" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libtwolame wrapper. The
<code>twolame</code>-equivalent options follow the FFmpeg ones and are in
parentheses.
</p>
<dl compact="compact">
<dt><samp>b (<em>-b</em>)</samp></dt>
<dd><p>Set bitrate expressed in bits/s for CBR. <code>twolame</code> <samp>b</samp>
option is expressed in kilobits/s. Default value is 128k.
</p>
</dd>
<dt><samp>q (<em>-V</em>)</samp></dt>
<dd><p>Set quality for experimental VBR support. Maximum value range is
from -50 to 50, useful range is from -10 to 10. The higher the
value, the better the quality. This option is valid only using the
<code>ffmpeg</code> command-line tool. For library interface users,
use <samp>global_quality</samp>.
</p>
</dd>
<dt><samp>mode (<em>--mode</em>)</samp></dt>
<dd><p>Set the mode of the resulting audio. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Choose mode automatically based on the input. This is the default.
</p></dd>
<dt>‘<samp>stereo</samp>’</dt>
<dd><p>Stereo
</p></dd>
<dt>‘<samp>joint_stereo</samp>’</dt>
<dd><p>Joint stereo
</p></dd>
<dt>‘<samp>dual_channel</samp>’</dt>
<dd><p>Dual channel
</p></dd>
<dt>‘<samp>mono</samp>’</dt>
<dd><p>Mono
</p></dd>
</dl>
</dd>
<dt><samp>psymodel (<em>--psyc-mode</em>)</samp></dt>
<dd><p>Set psychoacoustic model to use in encoding. The argument must be
an integer between -1 and 4, inclusive. The higher the value, the
better the quality. The default value is 3.
</p>
</dd>
<dt><samp>energy_levels (<em>--energy</em>)</samp></dt>
<dd><p>Enable energy levels extensions when set to 1. The default value is
0 (disabled).
</p>
</dd>
<dt><samp>error_protection (<em>--protect</em>)</samp></dt>
<dd><p>Enable CRC error protection when set to 1. The default value is 0
(disabled).
</p>
</dd>
<dt><samp>copyright (<em>--copyright</em>)</samp></dt>
<dd><p>Set MPEG audio copyright flag when set to 1. The default value is 0
(disabled).
</p>
</dd>
<dt><samp>original (<em>--original</em>)</samp></dt>
<dd><p>Set MPEG audio original flag when set to 1. The default value is 0
(disabled).
</p>
</dd>
</dl>
<a name="libvo_002daacenc"></a><a name="libvo_002daacenc-1"></a>
<h3 class="section">16.10 libvo-aacenc<span class="pull-right"><a class="anchor hidden-xs" href="#libvo_002daacenc-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libvo_002daacenc-1" aria-hidden="true">TOC</a></span></h3>
<p>VisualOn AAC encoder.
</p>
<p>Requires the presence of the libvo-aacenc headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libvo-aacenc --enable-version3</code>.
</p>
<p>This encoder is considered to be worse than the
<a href="#aacenc">native experimental FFmpeg AAC encoder</a>, according to
multiple sources.
</p>
<a name="Options-14"></a>
<h4 class="subsection">16.10.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-14" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-14" aria-hidden="true">TOC</a></span></h4>
<p>The VisualOn AAC encoder only support encoding AAC-LC and up to 2
channels. It is also CBR-only.
</p>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set bit rate in bits/s.
</p>
</dd>
</dl>
<a name="libvo_002damrwbenc"></a>
<h3 class="section">16.11 libvo-amrwbenc<span class="pull-right"><a class="anchor hidden-xs" href="#libvo_002damrwbenc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libvo_002damrwbenc" aria-hidden="true">TOC</a></span></h3>
<p>VisualOn Adaptive Multi-Rate Wideband encoder.
</p>
<p>Requires the presence of the libvo-amrwbenc headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libvo-amrwbenc --enable-version3</code>.
</p>
<p>This is a mono-only encoder. Officially it only supports 16000Hz sample
rate, but you can override it by setting <samp>strict</samp> to
‘<samp>unofficial</samp>’ or lower.
</p>
<a name="Options-15"></a>
<h4 class="subsection">16.11.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-15" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-15" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set bitrate in bits/s. Only the following bitrates are supported, otherwise
libavcodec will round to the nearest valid bitrate.
</p>
<dl compact="compact">
<dt>‘<samp>6600</samp>’</dt>
<dt>‘<samp>8850</samp>’</dt>
<dt>‘<samp>12650</samp>’</dt>
<dt>‘<samp>14250</samp>’</dt>
<dt>‘<samp>15850</samp>’</dt>
<dt>‘<samp>18250</samp>’</dt>
<dt>‘<samp>19850</samp>’</dt>
<dt>‘<samp>23050</samp>’</dt>
<dt>‘<samp>23850</samp>’</dt>
</dl>
</dd>
<dt><samp>dtx</samp></dt>
<dd><p>Allow discontinuous transmission (generate comfort noise) when set to 1. The
default value is 0 (disabled).
</p>
</dd>
</dl>
<a name="libopus-1"></a>
<h3 class="section">16.12 libopus<span class="pull-right"><a class="anchor hidden-xs" href="#libopus-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libopus-1" aria-hidden="true">TOC</a></span></h3>
<p>libopus Opus Interactive Audio Codec encoder wrapper.
</p>
<p>Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libopus</code>.
</p>
<a name="Option-Mapping"></a>
<h4 class="subsection">16.12.1 Option Mapping<span class="pull-right"><a class="anchor hidden-xs" href="#Option-Mapping" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Option-Mapping" aria-hidden="true">TOC</a></span></h4>
<p>Most libopus options are modelled after the <code>opusenc</code> utility from
opus-tools. The following is an option mapping chart describing options
supported by the libopus wrapper, and their <code>opusenc</code>-equivalent
in parentheses.
</p>
<dl compact="compact">
<dt><samp>b (<em>bitrate</em>)</samp></dt>
<dd><p>Set the bit rate in bits/s. FFmpeg’s <samp>b</samp> option is
expressed in bits/s, while <code>opusenc</code>’s <samp>bitrate</samp> in
kilobits/s.
</p>
</dd>
<dt><samp>vbr (<em>vbr</em>, <em>hard-cbr</em>, and <em>cvbr</em>)</samp></dt>
<dd><p>Set VBR mode. The FFmpeg <samp>vbr</samp> option has the following
valid arguments, with the their <code>opusenc</code> equivalent options
in parentheses:
</p>
<dl compact="compact">
<dt>‘<samp>off (<em>hard-cbr</em>)</samp>’</dt>
<dd><p>Use constant bit rate encoding.
</p>
</dd>
<dt>‘<samp>on (<em>vbr</em>)</samp>’</dt>
<dd><p>Use variable bit rate encoding (the default).
</p>
</dd>
<dt>‘<samp>constrained (<em>cvbr</em>)</samp>’</dt>
<dd><p>Use constrained variable bit rate encoding.
</p></dd>
</dl>
</dd>
<dt><samp>compression_level (<em>comp</em>)</samp></dt>
<dd><p>Set encoding algorithm complexity. Valid options are integers in
the 0-10 range. 0 gives the fastest encodes but lower quality, while 10
gives the highest quality but slowest encoding. The default is 10.
</p>
</dd>
<dt><samp>frame_duration (<em>framesize</em>)</samp></dt>
<dd><p>Set maximum frame size, or duration of a frame in milliseconds. The
argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller
frame sizes achieve lower latency but less quality at a given bitrate.
Sizes greater than 20ms are only interesting at fairly low bitrates.
The default is 20ms.
</p>
</dd>
<dt><samp>packet_loss (<em>expect-loss</em>)</samp></dt>
<dd><p>Set expected packet loss percentage. The default is 0.
</p>
</dd>
<dt><samp>application (N.A.)</samp></dt>
<dd><p>Set intended application type. Valid options are listed below:
</p>
<dl compact="compact">
<dt>‘<samp>voip</samp>’</dt>
<dd><p>Favor improved speech intelligibility.
</p></dd>
<dt>‘<samp>audio</samp>’</dt>
<dd><p>Favor faithfulness to the input (the default).
</p></dd>
<dt>‘<samp>lowdelay</samp>’</dt>
<dd><p>Restrict to only the lowest delay modes.
</p></dd>
</dl>
</dd>
<dt><samp>cutoff (N.A.)</samp></dt>
<dd><p>Set cutoff bandwidth in Hz. The argument must be exactly one of the
following: 4000, 6000, 8000, 12000, or 20000, corresponding to
narrowband, mediumband, wideband, super wideband, and fullband
respectively. The default is 0 (cutoff disabled).
</p>
</dd>
</dl>
<a name="libvorbis"></a>
<h3 class="section">16.13 libvorbis<span class="pull-right"><a class="anchor hidden-xs" href="#libvorbis" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libvorbis" aria-hidden="true">TOC</a></span></h3>
<p>libvorbis encoder wrapper.
</p>
<p>Requires the presence of the libvorbisenc headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libvorbis</code>.
</p>
<a name="Options-16"></a>
<h4 class="subsection">16.13.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-16" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-16" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libvorbis wrapper. The
<code>oggenc</code>-equivalent of the options are listed in parentheses.
</p>
<p>To get a more accurate and extensive documentation of the libvorbis
options, consult the libvorbisenc’s and <code>oggenc</code>’s documentations.
See <a href="http://xiph.org/vorbis/">http://xiph.org/vorbis/</a>,
<a href="http://wiki.xiph.org/Vorbis-tools">http://wiki.xiph.org/Vorbis-tools</a>, and oggenc(1).
</p>
<dl compact="compact">
<dt><samp>b (<em>-b</em>)</samp></dt>
<dd><p>Set bitrate expressed in bits/s for ABR. <code>oggenc</code> <samp>-b</samp> is
expressed in kilobits/s.
</p>
</dd>
<dt><samp>q (<em>-q</em>)</samp></dt>
<dd><p>Set constant quality setting for VBR. The value should be a float
number in the range of -1.0 to 10.0. The higher the value, the better
the quality. The default value is ‘<samp>3.0</samp>’.
</p>
<p>This option is valid only using the <code>ffmpeg</code> command-line tool.
For library interface users, use <samp>global_quality</samp>.
</p>
</dd>
<dt><samp>cutoff (<em>--advanced-encode-option lowpass_frequency=N</em>)</samp></dt>
<dd><p>Set cutoff bandwidth in Hz, a value of 0 disables cutoff. <code>oggenc</code>’s
related option is expressed in kHz. The default value is ‘<samp>0</samp>’ (cutoff
disabled).
</p>
</dd>
<dt><samp>minrate (<em>-m</em>)</samp></dt>
<dd><p>Set minimum bitrate expressed in bits/s. <code>oggenc</code> <samp>-m</samp> is
expressed in kilobits/s.
</p>
</dd>
<dt><samp>maxrate (<em>-M</em>)</samp></dt>
<dd><p>Set maximum bitrate expressed in bits/s. <code>oggenc</code> <samp>-M</samp> is
expressed in kilobits/s. This only has effect on ABR mode.
</p>
</dd>
<dt><samp>iblock (<em>--advanced-encode-option impulse_noisetune=N</em>)</samp></dt>
<dd><p>Set noise floor bias for impulse blocks. The value is a float number from
-15.0 to 0.0. A negative bias instructs the encoder to pay special attention
to the crispness of transients in the encoded audio. The tradeoff for better
transient response is a higher bitrate.
</p>
</dd>
</dl>
<a name="libwavpack"></a><a name="libwavpack-1"></a>
<h3 class="section">16.14 libwavpack<span class="pull-right"><a class="anchor hidden-xs" href="#libwavpack-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libwavpack-1" aria-hidden="true">TOC</a></span></h3>
<p>A wrapper providing WavPack encoding through libwavpack.
</p>
<p>Only lossless mode using 32-bit integer samples is supported currently.
</p>
<p>Requires the presence of the libwavpack headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libwavpack</code>.
</p>
<p>Note that a libavcodec-native encoder for the WavPack codec exists so users can
encode audios with this codec without using this encoder. See <a href="#wavpackenc">wavpackenc</a>.
</p>
<a name="Options-17"></a>
<h4 class="subsection">16.14.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-17" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-17" aria-hidden="true">TOC</a></span></h4>
<p><code>wavpack</code> command line utility’s corresponding options are listed in
parentheses, if any.
</p>
<dl compact="compact">
<dt><samp>frame_size (<em>--blocksize</em>)</samp></dt>
<dd><p>Default is 32768.
</p>
</dd>
<dt><samp>compression_level</samp></dt>
<dd><p>Set speed vs. compression tradeoff. Acceptable arguments are listed below:
</p>
<dl compact="compact">
<dt>‘<samp>0 (<em>-f</em>)</samp>’</dt>
<dd><p>Fast mode.
</p>
</dd>
<dt>‘<samp>1</samp>’</dt>
<dd><p>Normal (default) settings.
</p>
</dd>
<dt>‘<samp>2 (<em>-h</em>)</samp>’</dt>
<dd><p>High quality.
</p>
</dd>
<dt>‘<samp>3 (<em>-hh</em>)</samp>’</dt>
<dd><p>Very high quality.
</p>
</dd>
<dt>‘<samp>4-8 (<em>-hh -x</em><var>EXTRAPROC</var>)</samp>’</dt>
<dd><p>Same as ‘<samp>3</samp>’, but with extra processing enabled.
</p>
<p>‘<samp>4</samp>’ is the same as <samp>-x2</samp> and ‘<samp>8</samp>’ is the same as <samp>-x6</samp>.
</p>
</dd>
</dl>
</dd>
</dl>
<a name="wavpackenc"></a><a name="wavpack"></a>
<h3 class="section">16.15 wavpack<span class="pull-right"><a class="anchor hidden-xs" href="#wavpack" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-wavpack" aria-hidden="true">TOC</a></span></h3>
<p>WavPack lossless audio encoder.
</p>
<p>This is a libavcodec-native WavPack encoder. There is also an encoder based on
libwavpack, but there is virtually no reason to use that encoder.
</p>
<p>See also <a href="#libwavpack">libwavpack</a>.
</p>
<a name="Options-18"></a>
<h4 class="subsection">16.15.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-18" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-18" aria-hidden="true">TOC</a></span></h4>
<p>The equivalent options for <code>wavpack</code> command line utility are listed in
parentheses.
</p>
<a name="Shared-options"></a>
<h4 class="subsubsection">16.15.1.1 Shared options<span class="pull-right"><a class="anchor hidden-xs" href="#Shared-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Shared-options" aria-hidden="true">TOC</a></span></h4>
<p>The following shared options are effective for this encoder. Only special notes
about this particular encoder will be documented here. For the general meaning
of the options, see <a href="#codec_002doptions">the Codec Options chapter</a>.
</p>
<dl compact="compact">
<dt><samp>frame_size (<em>--blocksize</em>)</samp></dt>
<dd><p>For this encoder, the range for this option is between 128 and 131072. Default
is automatically decided based on sample rate and number of channel.
</p>
<p>For the complete formula of calculating default, see
<samp>libavcodec/wavpackenc.c</samp>.
</p>
</dd>
<dt><samp>compression_level (<em>-f</em>, <em>-h</em>, <em>-hh</em>, and <em>-x</em>)</samp></dt>
<dd><p>This option’s syntax is consistent with <a href="#libwavpack">libwavpack</a>’s.
</p></dd>
</dl>
<a name="Private-options"></a>
<h4 class="subsubsection">16.15.1.2 Private options<span class="pull-right"><a class="anchor hidden-xs" href="#Private-options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Private-options" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>joint_stereo (<em>-j</em>)</samp></dt>
<dd><p>Set whether to enable joint stereo. Valid values are:
</p>
<dl compact="compact">
<dt>‘<samp>on (<em>1</em>)</samp>’</dt>
<dd><p>Force mid/side audio encoding.
</p></dd>
<dt>‘<samp>off (<em>0</em>)</samp>’</dt>
<dd><p>Force left/right audio encoding.
</p></dd>
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Let the encoder decide automatically.
</p></dd>
</dl>
</dd>
<dt><samp>optimize_mono</samp></dt>
<dd><p>Set whether to enable optimization for mono. This option is only effective for
non-mono streams. Available values:
</p>
<dl compact="compact">
<dt>‘<samp>on</samp>’</dt>
<dd><p>enabled
</p></dd>
<dt>‘<samp>off</samp>’</dt>
<dd><p>disabled
</p></dd>
</dl>
</dd>
</dl>
<a name="Video-Encoders"></a>
<h2 class="chapter">17 Video Encoders<span class="pull-right"><a class="anchor hidden-xs" href="#Video-Encoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-Encoders" aria-hidden="true">TOC</a></span></h2>
<p>A description of some of the currently available video encoders
follows.
</p>
<a name="jpeg2000"></a>
<h3 class="section">17.1 jpeg2000<span class="pull-right"><a class="anchor hidden-xs" href="#jpeg2000" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-jpeg2000" aria-hidden="true">TOC</a></span></h3>
<p>The native jpeg 2000 encoder is lossy by default, the <code>-q:v</code>
option can be used to set the encoding quality. Lossless encoding
can be selected with <code>-pred 1</code>.
</p>
<a name="Options-19"></a>
<h4 class="subsection">17.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-19" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-19" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>format</samp></dt>
<dd><p>Can be set to either <code>j2k</code> or <code>jp2</code> (the default) that
makes it possible to store non-rgb pix_fmts.
</p>
</dd>
</dl>
<a name="snow"></a>
<h3 class="section">17.2 snow<span class="pull-right"><a class="anchor hidden-xs" href="#snow" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-snow" aria-hidden="true">TOC</a></span></h3>
<a name="Options-20"></a>
<h4 class="subsection">17.2.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-20" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-20" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>iterative_dia_size</samp></dt>
<dd><p>dia size for the iterative motion estimation
</p></dd>
</dl>
<a name="libtheora"></a>
<h3 class="section">17.3 libtheora<span class="pull-right"><a class="anchor hidden-xs" href="#libtheora" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libtheora" aria-hidden="true">TOC</a></span></h3>
<p>libtheora Theora encoder wrapper.
</p>
<p>Requires the presence of the libtheora headers and library during
configuration. You need to explicitly configure the build with
<code>--enable-libtheora</code>.
</p>
<p>For more information about the libtheora project see
<a href="http://www.theora.org/">http://www.theora.org/</a>.
</p>
<a name="Options-21"></a>
<h4 class="subsection">17.3.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-21" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-21" aria-hidden="true">TOC</a></span></h4>
<p>The following global options are mapped to internal libtheora options
which affect the quality and the bitrate of the encoded stream.
</p>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In
case VBR (Variable Bit Rate) mode is enabled this option is ignored.
</p>
</dd>
<dt><samp>flags</samp></dt>
<dd><p>Used to enable constant quality mode (VBR) encoding through the
<samp>qscale</samp> flag, and to enable the <code>pass1</code> and <code>pass2</code>
modes.
</p>
</dd>
<dt><samp>g</samp></dt>
<dd><p>Set the GOP size.
</p>
</dd>
<dt><samp>global_quality</samp></dt>
<dd><p>Set the global quality as an integer in lambda units.
</p>
<p>Only relevant when VBR mode is enabled with <code>flags +qscale</code>. The
value is converted to QP units by dividing it by <code>FF_QP2LAMBDA</code>,
clipped in the [0 - 10] range, and then multiplied by 6.3 to get a
value in the native libtheora range [0-63]. A higher value corresponds
to a higher quality.
</p>
</dd>
<dt><samp>q</samp></dt>
<dd><p>Enable VBR mode when set to a non-negative value, and set constant
quality value as a double floating point value in QP units.
</p>
<p>The value is clipped in the [0-10] range, and then multiplied by 6.3
to get a value in the native libtheora range [0-63].
</p>
<p>This option is valid only using the <code>ffmpeg</code> command-line
tool. For library interface users, use <samp>global_quality</samp>.
</p></dd>
</dl>
<a name="Examples-4"></a>
<h4 class="subsection">17.3.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-4" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-4" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Set maximum constant quality (VBR) encoding with <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg
</pre></div>
</li><li> Use <code>ffmpeg</code> to convert a CBR 1000 kbps Theora video stream:
<div class="example">
<pre class="example">ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg
</pre></div>
</li></ul>
<a name="libvpx"></a>
<h3 class="section">17.4 libvpx<span class="pull-right"><a class="anchor hidden-xs" href="#libvpx" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libvpx" aria-hidden="true">TOC</a></span></h3>
<p>VP8/VP9 format supported through libvpx.
</p>
<p>Requires the presence of the libvpx headers and library during configuration.
You need to explicitly configure the build with <code>--enable-libvpx</code>.
</p>
<a name="Options-22"></a>
<h4 class="subsection">17.4.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-22" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-22" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libvpx wrapper. The
<code>vpxenc</code>-equivalent options or values are listed in parentheses
for easy migration.
</p>
<p>To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
<a href="#codec_002doptions">the Codec Options chapter</a>.
</p>
<p>To get more documentation of the libvpx options, invoke the command
<code>ffmpeg -h encoder=libvpx</code>, <code>ffmpeg -h encoder=libvpx-vp9</code> or
<code>vpxenc --help</code>. Further information is available in the libvpx API
documentation.
</p>
<dl compact="compact">
<dt><samp>b (<em>target-bitrate</em>)</samp></dt>
<dd><p>Set bitrate in bits/s. Note that FFmpeg’s <samp>b</samp> option is
expressed in bits/s, while <code>vpxenc</code>’s <samp>target-bitrate</samp> is in
kilobits/s.
</p>
</dd>
<dt><samp>g (<em>kf-max-dist</em>)</samp></dt>
<dt><samp>keyint_min (<em>kf-min-dist</em>)</samp></dt>
<dt><samp>qmin (<em>min-q</em>)</samp></dt>
<dt><samp>qmax (<em>max-q</em>)</samp></dt>
<dt><samp>bufsize (<em>buf-sz</em>, <em>buf-optimal-sz</em>)</samp></dt>
<dd><p>Set ratecontrol buffer size (in bits). Note <code>vpxenc</code>’s options are
specified in milliseconds, the libvpx wrapper converts this value as follows:
<code>buf-sz = bufsize * 1000 / bitrate</code>,
<code>buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6</code>.
</p>
</dd>
<dt><samp>rc_init_occupancy (<em>buf-initial-sz</em>)</samp></dt>
<dd><p>Set number of bits which should be loaded into the rc buffer before decoding
starts. Note <code>vpxenc</code>’s option is specified in milliseconds, the libvpx
wrapper converts this value as follows:
<code>rc_init_occupancy * 1000 / bitrate</code>.
</p>
</dd>
<dt><samp>undershoot-pct</samp></dt>
<dd><p>Set datarate undershoot (min) percentage of the target bitrate.
</p>
</dd>
<dt><samp>overshoot-pct</samp></dt>
<dd><p>Set datarate overshoot (max) percentage of the target bitrate.
</p>
</dd>
<dt><samp>skip_threshold (<em>drop-frame</em>)</samp></dt>
<dt><samp>qcomp (<em>bias-pct</em>)</samp></dt>
<dt><samp>maxrate (<em>maxsection-pct</em>)</samp></dt>
<dd><p>Set GOP max bitrate in bits/s. Note <code>vpxenc</code>’s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: <code>(maxrate * 100 / bitrate)</code>.
</p>
</dd>
<dt><samp>minrate (<em>minsection-pct</em>)</samp></dt>
<dd><p>Set GOP min bitrate in bits/s. Note <code>vpxenc</code>’s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: <code>(minrate * 100 / bitrate)</code>.
</p>
</dd>
<dt><samp>minrate, maxrate, b <em>end-usage=cbr</em></samp></dt>
<dd><p><code>(minrate == maxrate == bitrate)</code>.
</p>
</dd>
<dt><samp>crf (<em>end-usage=cq</em>, <em>cq-level</em>)</samp></dt>
<dt><samp>quality, deadline (<em>deadline</em>)</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>best</samp>’</dt>
<dd><p>Use best quality deadline. Poorly named and quite slow, this option should be
avoided as it may give worse quality output than good.
</p></dd>
<dt>‘<samp>good</samp>’</dt>
<dd><p>Use good quality deadline. This is a good trade-off between speed and quality
when used with the <samp>cpu-used</samp> option.
</p></dd>
<dt>‘<samp>realtime</samp>’</dt>
<dd><p>Use realtime quality deadline.
</p></dd>
</dl>
</dd>
<dt><samp>speed, cpu-used (<em>cpu-used</em>)</samp></dt>
<dd><p>Set quality/speed ratio modifier. Higher values speed up the encode at the cost
of quality.
</p>
</dd>
<dt><samp>nr (<em>noise-sensitivity</em>)</samp></dt>
<dt><samp>static-thresh</samp></dt>
<dd><p>Set a change threshold on blocks below which they will be skipped by the
encoder.
</p>
</dd>
<dt><samp>slices (<em>token-parts</em>)</samp></dt>
<dd><p>Note that FFmpeg’s <samp>slices</samp> option gives the total number of partitions,
while <code>vpxenc</code>’s <samp>token-parts</samp> is given as
<code>log2(partitions)</code>.
</p>
</dd>
<dt><samp>max-intra-rate</samp></dt>
<dd><p>Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0
means unlimited.
</p>
</dd>
<dt><samp>force_key_frames</samp></dt>
<dd><p><code>VPX_EFLAG_FORCE_KF</code>
</p>
</dd>
<dt><samp>Alternate reference frame related</samp></dt>
<dd><dl compact="compact">
<dt><samp>auto-alt-ref</samp></dt>
<dd><p>Enable use of alternate reference frames (2-pass only).
</p></dd>
<dt><samp>arnr-max-frames</samp></dt>
<dd><p>Set altref noise reduction max frame count.
</p></dd>
<dt><samp>arnr-type</samp></dt>
<dd><p>Set altref noise reduction filter type: backward, forward, centered.
</p></dd>
<dt><samp>arnr-strength</samp></dt>
<dd><p>Set altref noise reduction filter strength.
</p></dd>
<dt><samp>rc-lookahead, lag-in-frames (<em>lag-in-frames</em>)</samp></dt>
<dd><p>Set number of frames to look ahead for frametype and ratecontrol.
</p></dd>
</dl>
</dd>
<dt><samp>error-resilient</samp></dt>
<dd><p>Enable error resiliency features.
</p>
</dd>
<dt><samp>VP9-specific options</samp></dt>
<dd><dl compact="compact">
<dt><samp>lossless</samp></dt>
<dd><p>Enable lossless mode.
</p></dd>
<dt><samp>tile-columns</samp></dt>
<dd><p>Set number of tile columns to use. Note this is given as
<code>log2(tile_columns)</code>. For example, 8 tile columns would be requested by
setting the <samp>tile-columns</samp> option to 3.
</p></dd>
<dt><samp>tile-rows</samp></dt>
<dd><p>Set number of tile rows to use. Note this is given as <code>log2(tile_rows)</code>.
For example, 4 tile rows would be requested by setting the <samp>tile-rows</samp>
option to 2.
</p></dd>
<dt><samp>frame-parallel</samp></dt>
<dd><p>Enable frame parallel decodability features.
</p></dd>
<dt><samp>aq-mode</samp></dt>
<dd><p>Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3:
cyclic refresh).
</p></dd>
<dt><samp>colorspace <em>color-space</em></samp></dt>
<dd><p>Set input color space. The VP9 bitstream supports signaling the following
colorspaces:
</p><dl compact="compact">
<dt><samp>‘<samp>rgb</samp>’ <em>sRGB</em></samp></dt>
<dt><samp>‘<samp>bt709</samp>’ <em>bt709</em></samp></dt>
<dt><samp>‘<samp>unspecified</samp>’ <em>unknown</em></samp></dt>
<dt><samp>‘<samp>bt470bg</samp>’ <em>bt601</em></samp></dt>
<dt><samp>‘<samp>smpte170m</samp>’ <em>smpte170</em></samp></dt>
<dt><samp>‘<samp>smpte240m</samp>’ <em>smpte240</em></samp></dt>
<dt><samp>‘<samp>bt2020_ncl</samp>’ <em>bt2020</em></samp></dt>
</dl>
</dd>
</dl>
</dd>
</dl>
<p>For more information about libvpx see:
<a href="http://www.webmproject.org/">http://www.webmproject.org/</a>
</p>
<a name="libwebp"></a>
<h3 class="section">17.5 libwebp<span class="pull-right"><a class="anchor hidden-xs" href="#libwebp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libwebp" aria-hidden="true">TOC</a></span></h3>
<p>libwebp WebP Image encoder wrapper
</p>
<p>libwebp is Google’s official encoder for WebP images. It can encode in either
lossy or lossless mode. Lossy images are essentially a wrapper around a VP8
frame. Lossless images are a separate codec developed by Google.
</p>
<a name="Pixel-Format"></a>
<h4 class="subsection">17.5.1 Pixel Format<span class="pull-right"><a class="anchor hidden-xs" href="#Pixel-Format" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Pixel-Format" aria-hidden="true">TOC</a></span></h4>
<p>Currently, libwebp only supports YUV420 for lossy and RGB for lossless due
to limitations of the format and libwebp. Alpha is supported for either mode.
Because of API limitations, if RGB is passed in when encoding lossy or YUV is
passed in for encoding lossless, the pixel format will automatically be
converted using functions from libwebp. This is not ideal and is done only for
convenience.
</p>
<a name="Options-23"></a>
<h4 class="subsection">17.5.2 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-23" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-23" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>-lossless <var>boolean</var></samp></dt>
<dd><p>Enables/Disables use of lossless mode. Default is 0.
</p>
</dd>
<dt><samp>-compression_level <var>integer</var></samp></dt>
<dd><p>For lossy, this is a quality/speed tradeoff. Higher values give better quality
for a given size at the cost of increased encoding time. For lossless, this is
a size/speed tradeoff. Higher values give smaller size at the cost of increased
encoding time. More specifically, it controls the number of extra algorithms
and compression tools used, and varies the combination of these tools. This
maps to the <var>method</var> option in libwebp. The valid range is 0 to 6.
Default is 4.
</p>
</dd>
<dt><samp>-qscale <var>float</var></samp></dt>
<dd><p>For lossy encoding, this controls image quality, 0 to 100. For lossless
encoding, this controls the effort and time spent at compressing more. The
default value is 75. Note that for usage via libavcodec, this option is called
<var>global_quality</var> and must be multiplied by <var>FF_QP2LAMBDA</var>.
</p>
</dd>
<dt><samp>-preset <var>type</var></samp></dt>
<dd><p>Configuration preset. This does some automatic settings based on the general
type of the image.
</p><dl compact="compact">
<dt><samp>none</samp></dt>
<dd><p>Do not use a preset.
</p></dd>
<dt><samp>default</samp></dt>
<dd><p>Use the encoder default.
</p></dd>
<dt><samp>picture</samp></dt>
<dd><p>Digital picture, like portrait, inner shot
</p></dd>
<dt><samp>photo</samp></dt>
<dd><p>Outdoor photograph, with natural lighting
</p></dd>
<dt><samp>drawing</samp></dt>
<dd><p>Hand or line drawing, with high-contrast details
</p></dd>
<dt><samp>icon</samp></dt>
<dd><p>Small-sized colorful images
</p></dd>
<dt><samp>text</samp></dt>
<dd><p>Text-like
</p></dd>
</dl>
</dd>
</dl>
<a name="libx264_002c-libx264rgb"></a>
<h3 class="section">17.6 libx264, libx264rgb<span class="pull-right"><a class="anchor hidden-xs" href="#libx264_002c-libx264rgb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libx264_002c-libx264rgb" aria-hidden="true">TOC</a></span></h3>
<p>x264 H.264/MPEG-4 AVC encoder wrapper.
</p>
<p>This encoder requires the presence of the libx264 headers and library
during configuration. You need to explicitly configure the build with
<code>--enable-libx264</code>.
</p>
<p>libx264 supports an impressive number of features, including 8x8 and
4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC
entropy coding, interlacing (MBAFF), lossless mode, psy optimizations
for detail retention (adaptive quantization, psy-RD, psy-trellis).
</p>
<p>Many libx264 encoder options are mapped to FFmpeg global codec
options, while unique encoder options are provided through private
options. Additionally the <samp>x264opts</samp> and <samp>x264-params</samp>
private options allows one to pass a list of key=value tuples as accepted
by the libx264 <code>x264_param_parse</code> function.
</p>
<p>The x264 project website is at
<a href="http://www.videolan.org/developers/x264.html">http://www.videolan.org/developers/x264.html</a>.
</p>
<p>The libx264rgb encoder is the same as libx264, except it accepts packed RGB
pixel formats as input instead of YUV.
</p>
<a name="Supported-Pixel-Formats"></a>
<h4 class="subsection">17.6.1 Supported Pixel Formats<span class="pull-right"><a class="anchor hidden-xs" href="#Supported-Pixel-Formats" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Supported-Pixel-Formats" aria-hidden="true">TOC</a></span></h4>
<p>x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at
x264’s configure time. FFmpeg only supports one bit depth in one particular
build. In other words, it is not possible to build one FFmpeg with multiple
versions of x264 with different bit depths.
</p>
<a name="Options-24"></a>
<h4 class="subsection">17.6.2 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-24" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-24" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libx264 wrapper. The
<code>x264</code>-equivalent options or values are listed in parentheses
for easy migration.
</p>
<p>To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
<a href="#codec_002doptions">the Codec Options chapter</a>.
</p>
<p>To get a more accurate and extensive documentation of the libx264
options, invoke the command <code>x264 --full-help</code> or consult
the libx264 documentation.
</p>
<dl compact="compact">
<dt><samp>b (<em>bitrate</em>)</samp></dt>
<dd><p>Set bitrate in bits/s. Note that FFmpeg’s <samp>b</samp> option is
expressed in bits/s, while <code>x264</code>’s <samp>bitrate</samp> is in
kilobits/s.
</p>
</dd>
<dt><samp>bf (<em>bframes</em>)</samp></dt>
<dt><samp>g (<em>keyint</em>)</samp></dt>
<dt><samp>qmin (<em>qpmin</em>)</samp></dt>
<dd><p>Minimum quantizer scale.
</p>
</dd>
<dt><samp>qmax (<em>qpmax</em>)</samp></dt>
<dd><p>Maximum quantizer scale.
</p>
</dd>
<dt><samp>qdiff (<em>qpstep</em>)</samp></dt>
<dd><p>Maximum difference between quantizer scales.
</p>
</dd>
<dt><samp>qblur (<em>qblur</em>)</samp></dt>
<dd><p>Quantizer curve blur
</p>
</dd>
<dt><samp>qcomp (<em>qcomp</em>)</samp></dt>
<dd><p>Quantizer curve compression factor
</p>
</dd>
<dt><samp>refs (<em>ref</em>)</samp></dt>
<dd><p>Number of reference frames each P-frame can use. The range is from <var>0-16</var>.
</p>
</dd>
<dt><samp>sc_threshold (<em>scenecut</em>)</samp></dt>
<dd><p>Sets the threshold for the scene change detection.
</p>
</dd>
<dt><samp>trellis (<em>trellis</em>)</samp></dt>
<dd><p>Performs Trellis quantization to increase efficiency. Enabled by default.
</p>
</dd>
<dt><samp>nr (<em>nr</em>)</samp></dt>
<dt><samp>me_range (<em>merange</em>)</samp></dt>
<dd><p>Maximum range of the motion search in pixels.
</p>
</dd>
<dt><samp>me_method (<em>me</em>)</samp></dt>
<dd><p>Set motion estimation method. Possible values in the decreasing order
of speed:
</p>
<dl compact="compact">
<dt>‘<samp>dia (<em>dia</em>)</samp>’</dt>
<dt>‘<samp>epzs (<em>dia</em>)</samp>’</dt>
<dd><p>Diamond search with radius 1 (fastest). ‘<samp>epzs</samp>’ is an alias for
‘<samp>dia</samp>’.
</p></dd>
<dt>‘<samp>hex (<em>hex</em>)</samp>’</dt>
<dd><p>Hexagonal search with radius 2.
</p></dd>
<dt>‘<samp>umh (<em>umh</em>)</samp>’</dt>
<dd><p>Uneven multi-hexagon search.
</p></dd>
<dt>‘<samp>esa (<em>esa</em>)</samp>’</dt>
<dd><p>Exhaustive search.
</p></dd>
<dt>‘<samp>tesa (<em>tesa</em>)</samp>’</dt>
<dd><p>Hadamard exhaustive search (slowest).
</p></dd>
</dl>
</dd>
<dt><samp>subq (<em>subme</em>)</samp></dt>
<dd><p>Sub-pixel motion estimation method.
</p>
</dd>
<dt><samp>b_strategy (<em>b-adapt</em>)</samp></dt>
<dd><p>Adaptive B-frame placement decision algorithm. Use only on first-pass.
</p>
</dd>
<dt><samp>keyint_min (<em>min-keyint</em>)</samp></dt>
<dd><p>Minimum GOP size.
</p>
</dd>
<dt><samp>coder</samp></dt>
<dd><p>Set entropy encoder. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>ac</samp>’</dt>
<dd><p>Enable CABAC.
</p>
</dd>
<dt>‘<samp>vlc</samp>’</dt>
<dd><p>Enable CAVLC and disable CABAC. It generates the same effect as
<code>x264</code>’s <samp>--no-cabac</samp> option.
</p></dd>
</dl>
</dd>
<dt><samp>cmp</samp></dt>
<dd><p>Set full pixel motion estimation comparation algorithm. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>chroma</samp>’</dt>
<dd><p>Enable chroma in motion estimation.
</p>
</dd>
<dt>‘<samp>sad</samp>’</dt>
<dd><p>Ignore chroma in motion estimation. It generates the same effect as
<code>x264</code>’s <samp>--no-chroma-me</samp> option.
</p></dd>
</dl>
</dd>
<dt><samp>threads (<em>threads</em>)</samp></dt>
<dd><p>Number of encoding threads.
</p>
</dd>
<dt><samp>thread_type</samp></dt>
<dd><p>Set multithreading technique. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>slice</samp>’</dt>
<dd><p>Slice-based multithreading. It generates the same effect as
<code>x264</code>’s <samp>--sliced-threads</samp> option.
</p></dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>Frame-based multithreading.
</p></dd>
</dl>
</dd>
<dt><samp>flags</samp></dt>
<dd><p>Set encoding flags. It can be used to disable closed GOP and enable
open GOP by setting it to <code>-cgop</code>. The result is similar to
the behavior of <code>x264</code>’s <samp>--open-gop</samp> option.
</p>
</dd>
<dt><samp>rc_init_occupancy (<em>vbv-init</em>)</samp></dt>
<dt><samp>preset (<em>preset</em>)</samp></dt>
<dd><p>Set the encoding preset.
</p>
</dd>
<dt><samp>tune (<em>tune</em>)</samp></dt>
<dd><p>Set tuning of the encoding params.
</p>
</dd>
<dt><samp>profile (<em>profile</em>)</samp></dt>
<dd><p>Set profile restrictions.
</p>
</dd>
<dt><samp>fastfirstpass</samp></dt>
<dd><p>Enable fast settings when encoding first pass, when set to 1. When set
to 0, it has the same effect of <code>x264</code>’s
<samp>--slow-firstpass</samp> option.
</p>
</dd>
<dt><samp>crf (<em>crf</em>)</samp></dt>
<dd><p>Set the quality for constant quality mode.
</p>
</dd>
<dt><samp>crf_max (<em>crf-max</em>)</samp></dt>
<dd><p>In CRF mode, prevents VBV from lowering quality beyond this point.
</p>
</dd>
<dt><samp>qp (<em>qp</em>)</samp></dt>
<dd><p>Set constant quantization rate control method parameter.
</p>
</dd>
<dt><samp>aq-mode (<em>aq-mode</em>)</samp></dt>
<dd><p>Set AQ method. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>none (<em>0</em>)</samp>’</dt>
<dd><p>Disabled.
</p>
</dd>
<dt>‘<samp>variance (<em>1</em>)</samp>’</dt>
<dd><p>Variance AQ (complexity mask).
</p>
</dd>
<dt>‘<samp>autovariance (<em>2</em>)</samp>’</dt>
<dd><p>Auto-variance AQ (experimental).
</p></dd>
</dl>
</dd>
<dt><samp>aq-strength (<em>aq-strength</em>)</samp></dt>
<dd><p>Set AQ strength, reduce blocking and blurring in flat and textured areas.
</p>
</dd>
<dt><samp>psy</samp></dt>
<dd><p>Use psychovisual optimizations when set to 1. When set to 0, it has the
same effect as <code>x264</code>’s <samp>--no-psy</samp> option.
</p>
</dd>
<dt><samp>psy-rd (<em>psy-rd</em>)</samp></dt>
<dd><p>Set strength of psychovisual optimization, in
<var>psy-rd</var>:<var>psy-trellis</var> format.
</p>
</dd>
<dt><samp>rc-lookahead (<em>rc-lookahead</em>)</samp></dt>
<dd><p>Set number of frames to look ahead for frametype and ratecontrol.
</p>
</dd>
<dt><samp>weightb</samp></dt>
<dd><p>Enable weighted prediction for B-frames when set to 1. When set to 0,
it has the same effect as <code>x264</code>’s <samp>--no-weightb</samp> option.
</p>
</dd>
<dt><samp>weightp (<em>weightp</em>)</samp></dt>
<dd><p>Set weighted prediction method for P-frames. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>none (<em>0</em>)</samp>’</dt>
<dd><p>Disabled
</p></dd>
<dt>‘<samp>simple (<em>1</em>)</samp>’</dt>
<dd><p>Enable only weighted refs
</p></dd>
<dt>‘<samp>smart (<em>2</em>)</samp>’</dt>
<dd><p>Enable both weighted refs and duplicates
</p></dd>
</dl>
</dd>
<dt><samp>ssim (<em>ssim</em>)</samp></dt>
<dd><p>Enable calculation and printing SSIM stats after the encoding.
</p>
</dd>
<dt><samp>intra-refresh (<em>intra-refresh</em>)</samp></dt>
<dd><p>Enable the use of Periodic Intra Refresh instead of IDR frames when set
to 1.
</p>
</dd>
<dt><samp>avcintra-class (<em>class</em>)</samp></dt>
<dd><p>Configure the encoder to generate AVC-Intra.
Valid values are 50,100 and 200
</p>
</dd>
<dt><samp>bluray-compat (<em>bluray-compat</em>)</samp></dt>
<dd><p>Configure the encoder to be compatible with the bluray standard.
It is a shorthand for setting "bluray-compat=1 force-cfr=1".
</p>
</dd>
<dt><samp>b-bias (<em>b-bias</em>)</samp></dt>
<dd><p>Set the influence on how often B-frames are used.
</p>
</dd>
<dt><samp>b-pyramid (<em>b-pyramid</em>)</samp></dt>
<dd><p>Set method for keeping of some B-frames as references. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>none (<em>none</em>)</samp>’</dt>
<dd><p>Disabled.
</p></dd>
<dt>‘<samp>strict (<em>strict</em>)</samp>’</dt>
<dd><p>Strictly hierarchical pyramid.
</p></dd>
<dt>‘<samp>normal (<em>normal</em>)</samp>’</dt>
<dd><p>Non-strict (not Blu-ray compatible).
</p></dd>
</dl>
</dd>
<dt><samp>mixed-refs</samp></dt>
<dd><p>Enable the use of one reference per partition, as opposed to one
reference per macroblock when set to 1. When set to 0, it has the
same effect as <code>x264</code>’s <samp>--no-mixed-refs</samp> option.
</p>
</dd>
<dt><samp>8x8dct</samp></dt>
<dd><p>Enable adaptive spatial transform (high profile 8x8 transform)
when set to 1. When set to 0, it has the same effect as
<code>x264</code>’s <samp>--no-8x8dct</samp> option.
</p>
</dd>
<dt><samp>fast-pskip</samp></dt>
<dd><p>Enable early SKIP detection on P-frames when set to 1. When set
to 0, it has the same effect as <code>x264</code>’s
<samp>--no-fast-pskip</samp> option.
</p>
</dd>
<dt><samp>aud (<em>aud</em>)</samp></dt>
<dd><p>Enable use of access unit delimiters when set to 1.
</p>
</dd>
<dt><samp>mbtree</samp></dt>
<dd><p>Enable use macroblock tree ratecontrol when set to 1. When set
to 0, it has the same effect as <code>x264</code>’s
<samp>--no-mbtree</samp> option.
</p>
</dd>
<dt><samp>deblock (<em>deblock</em>)</samp></dt>
<dd><p>Set loop filter parameters, in <var>alpha</var>:<var>beta</var> form.
</p>
</dd>
<dt><samp>cplxblur (<em>cplxblur</em>)</samp></dt>
<dd><p>Set fluctuations reduction in QP (before curve compression).
</p>
</dd>
<dt><samp>partitions (<em>partitions</em>)</samp></dt>
<dd><p>Set partitions to consider as a comma-separated list of. Possible
values in the list:
</p>
<dl compact="compact">
<dt>‘<samp>p8x8</samp>’</dt>
<dd><p>8x8 P-frame partition.
</p></dd>
<dt>‘<samp>p4x4</samp>’</dt>
<dd><p>4x4 P-frame partition.
</p></dd>
<dt>‘<samp>b8x8</samp>’</dt>
<dd><p>4x4 B-frame partition.
</p></dd>
<dt>‘<samp>i8x8</samp>’</dt>
<dd><p>8x8 I-frame partition.
</p></dd>
<dt>‘<samp>i4x4</samp>’</dt>
<dd><p>4x4 I-frame partition.
(Enabling ‘<samp>p4x4</samp>’ requires ‘<samp>p8x8</samp>’ to be enabled. Enabling
‘<samp>i8x8</samp>’ requires adaptive spatial transform (<samp>8x8dct</samp>
option) to be enabled.)
</p></dd>
<dt>‘<samp>none (<em>none</em>)</samp>’</dt>
<dd><p>Do not consider any partitions.
</p></dd>
<dt>‘<samp>all (<em>all</em>)</samp>’</dt>
<dd><p>Consider every partition.
</p></dd>
</dl>
</dd>
<dt><samp>direct-pred (<em>direct</em>)</samp></dt>
<dd><p>Set direct MV prediction mode. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>none (<em>none</em>)</samp>’</dt>
<dd><p>Disable MV prediction.
</p></dd>
<dt>‘<samp>spatial (<em>spatial</em>)</samp>’</dt>
<dd><p>Enable spatial predicting.
</p></dd>
<dt>‘<samp>temporal (<em>temporal</em>)</samp>’</dt>
<dd><p>Enable temporal predicting.
</p></dd>
<dt>‘<samp>auto (<em>auto</em>)</samp>’</dt>
<dd><p>Automatically decided.
</p></dd>
</dl>
</dd>
<dt><samp>slice-max-size (<em>slice-max-size</em>)</samp></dt>
<dd><p>Set the limit of the size of each slice in bytes. If not specified
but RTP payload size (<samp>ps</samp>) is specified, that is used.
</p>
</dd>
<dt><samp>stats (<em>stats</em>)</samp></dt>
<dd><p>Set the file name for multi-pass stats.
</p>
</dd>
<dt><samp>nal-hrd (<em>nal-hrd</em>)</samp></dt>
<dd><p>Set signal HRD information (requires <samp>vbv-bufsize</samp> to be set).
Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>none (<em>none</em>)</samp>’</dt>
<dd><p>Disable HRD information signaling.
</p></dd>
<dt>‘<samp>vbr (<em>vbr</em>)</samp>’</dt>
<dd><p>Variable bit rate.
</p></dd>
<dt>‘<samp>cbr (<em>cbr</em>)</samp>’</dt>
<dd><p>Constant bit rate (not allowed in MP4 container).
</p></dd>
</dl>
</dd>
<dt><samp>x264opts (N.A.)</samp></dt>
<dd><p>Set any x264 option, see <code>x264 --fullhelp</code> for a list.
</p>
<p>Argument is a list of <var>key</var>=<var>value</var> couples separated by
":". In <var>filter</var> and <var>psy-rd</var> options that use ":" as a separator
themselves, use "," instead. They accept it as well since long ago but this
is kept undocumented for some reason.
</p>
<p>For example to specify libx264 encoding options with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
</pre></div>
</dd>
<dt><samp>x264-params (N.A.)</samp></dt>
<dd><p>Override the x264 configuration using a :-separated list of key=value
parameters.
</p>
<p>This option is functionally the same as the <samp>x264opts</samp>, but is
duplicated for compatibility with the Libav fork.
</p>
<p>For example to specify libx264 encoding options with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT
</pre></div>
</dd>
</dl>
<p>Encoding ffpresets for common usages are provided so they can be used with the
general presets system (e.g. passing the <samp>pre</samp> option).
</p>
<a name="libx265"></a>
<h3 class="section">17.7 libx265<span class="pull-right"><a class="anchor hidden-xs" href="#libx265" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libx265" aria-hidden="true">TOC</a></span></h3>
<p>x265 H.265/HEVC encoder wrapper.
</p>
<p>This encoder requires the presence of the libx265 headers and library
during configuration. You need to explicitly configure the build with
<samp>--enable-libx265</samp>.
</p>
<a name="Options-25"></a>
<h4 class="subsection">17.7.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-25" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-25" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>preset</samp></dt>
<dd><p>Set the x265 preset.
</p>
</dd>
<dt><samp>tune</samp></dt>
<dd><p>Set the x265 tune parameter.
</p>
</dd>
<dt><samp>x265-params</samp></dt>
<dd><p>Set x265 options using a list of <var>key</var>=<var>value</var> couples separated
by ":". See <code>x265 --help</code> for a list of options.
</p>
<p>For example to specify libx265 encoding options with <samp>-x265-params</samp>:
</p>
<div class="example">
<pre class="example">ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4
</pre></div>
</dd>
</dl>
<a name="libxvid"></a>
<h3 class="section">17.8 libxvid<span class="pull-right"><a class="anchor hidden-xs" href="#libxvid" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libxvid" aria-hidden="true">TOC</a></span></h3>
<p>Xvid MPEG-4 Part 2 encoder wrapper.
</p>
<p>This encoder requires the presence of the libxvidcore headers and library
during configuration. You need to explicitly configure the build with
<code>--enable-libxvid --enable-gpl</code>.
</p>
<p>The native <code>mpeg4</code> encoder supports the MPEG-4 Part 2 format, so
users can encode to this format without this library.
</p>
<a name="Options-26"></a>
<h4 class="subsection">17.8.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-26" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-26" aria-hidden="true">TOC</a></span></h4>
<p>The following options are supported by the libxvid wrapper. Some of
the following options are listed but are not documented, and
correspond to shared codec options. See <a href="#codec_002doptions">the Codec
Options chapter</a> for their documentation. The other shared options
which are not listed have no effect for the libxvid encoder.
</p>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dt><samp>g</samp></dt>
<dt><samp>qmin</samp></dt>
<dt><samp>qmax</samp></dt>
<dt><samp>mpeg_quant</samp></dt>
<dt><samp>threads</samp></dt>
<dt><samp>bf</samp></dt>
<dt><samp>b_qfactor</samp></dt>
<dt><samp>b_qoffset</samp></dt>
<dt><samp>flags</samp></dt>
<dd><p>Set specific encoding flags. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>mv4</samp>’</dt>
<dd><p>Use four motion vector by macroblock.
</p>
</dd>
<dt>‘<samp>aic</samp>’</dt>
<dd><p>Enable high quality AC prediction.
</p>
</dd>
<dt>‘<samp>gray</samp>’</dt>
<dd><p>Only encode grayscale.
</p>
</dd>
<dt>‘<samp>gmc</samp>’</dt>
<dd><p>Enable the use of global motion compensation (GMC).
</p>
</dd>
<dt>‘<samp>qpel</samp>’</dt>
<dd><p>Enable quarter-pixel motion compensation.
</p>
</dd>
<dt>‘<samp>cgop</samp>’</dt>
<dd><p>Enable closed GOP.
</p>
</dd>
<dt>‘<samp>global_header</samp>’</dt>
<dd><p>Place global headers in extradata instead of every keyframe.
</p>
</dd>
</dl>
</dd>
<dt><samp>trellis</samp></dt>
<dt><samp>me_method</samp></dt>
<dd><p>Set motion estimation method. Possible values in decreasing order of
speed and increasing order of quality:
</p>
<dl compact="compact">
<dt>‘<samp>zero</samp>’</dt>
<dd><p>Use no motion estimation (default).
</p>
</dd>
<dt>‘<samp>phods</samp>’</dt>
<dt>‘<samp>x1</samp>’</dt>
<dt>‘<samp>log</samp>’</dt>
<dd><p>Enable advanced diamond zonal search for 16x16 blocks and half-pixel
refinement for 16x16 blocks. ‘<samp>x1</samp>’ and ‘<samp>log</samp>’ are aliases for
‘<samp>phods</samp>’.
</p>
</dd>
<dt>‘<samp>epzs</samp>’</dt>
<dd><p>Enable all of the things described above, plus advanced diamond zonal
search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion
estimation on chroma planes.
</p>
</dd>
<dt>‘<samp>full</samp>’</dt>
<dd><p>Enable all of the things described above, plus extended 16x16 and 8x8
blocks search.
</p></dd>
</dl>
</dd>
<dt><samp>mbd</samp></dt>
<dd><p>Set macroblock decision algorithm. Possible values in the increasing
order of quality:
</p>
<dl compact="compact">
<dt>‘<samp>simple</samp>’</dt>
<dd><p>Use macroblock comparing function algorithm (default).
</p>
</dd>
<dt>‘<samp>bits</samp>’</dt>
<dd><p>Enable rate distortion-based half pixel and quarter pixel refinement for
16x16 blocks.
</p>
</dd>
<dt>‘<samp>rd</samp>’</dt>
<dd><p>Enable all of the things described above, plus rate distortion-based
half pixel and quarter pixel refinement for 8x8 blocks, and rate
distortion-based search using square pattern.
</p></dd>
</dl>
</dd>
<dt><samp>lumi_aq</samp></dt>
<dd><p>Enable lumi masking adaptive quantization when set to 1. Default is 0
(disabled).
</p>
</dd>
<dt><samp>variance_aq</samp></dt>
<dd><p>Enable variance adaptive quantization when set to 1. Default is 0
(disabled).
</p>
<p>When combined with <samp>lumi_aq</samp>, the resulting quality will not
be better than any of the two specified individually. In other
words, the resulting quality will be the worse one of the two
effects.
</p>
</dd>
<dt><samp>ssim</samp></dt>
<dd><p>Set structural similarity (SSIM) displaying method. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>off</samp>’</dt>
<dd><p>Disable displaying of SSIM information.
</p>
</dd>
<dt>‘<samp>avg</samp>’</dt>
<dd><p>Output average SSIM at the end of encoding to stdout. The format of
showing the average SSIM is:
</p>
<div class="example">
<pre class="example">Average SSIM: %f
</pre></div>
<p>For users who are not familiar with C, %f means a float number, or
a decimal (e.g. 0.939232).
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>Output both per-frame SSIM data during encoding and average SSIM at
the end of encoding to stdout. The format of per-frame information
is:
</p>
<div class="example">
<pre class="example"> SSIM: avg: %1.3f min: %1.3f max: %1.3f
</pre></div>
<p>For users who are not familiar with C, %1.3f means a float number
rounded to 3 digits after the dot (e.g. 0.932).
</p>
</dd>
</dl>
</dd>
<dt><samp>ssim_acc</samp></dt>
<dd><p>Set SSIM accuracy. Valid options are integers within the range of
0-4, while 0 gives the most accurate result and 4 computes the
fastest.
</p>
</dd>
</dl>
<a name="mpeg2"></a>
<h3 class="section">17.9 mpeg2<span class="pull-right"><a class="anchor hidden-xs" href="#mpeg2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mpeg2" aria-hidden="true">TOC</a></span></h3>
<p>MPEG-2 video encoder.
</p>
<a name="Options-27"></a>
<h4 class="subsection">17.9.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-27" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-27" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>seq_disp_ext <var>integer</var></samp></dt>
<dd><p>Specifies if the encoder should write a sequence_display_extension to the
output.
</p><dl compact="compact">
<dt><samp>-1</samp></dt>
<dt><samp>auto</samp></dt>
<dd><p>Decide automatically to write it or not (this is the default) by checking if
the data to be written is different from the default or unspecified values.
</p></dd>
<dt><samp>0</samp></dt>
<dt><samp>never</samp></dt>
<dd><p>Never write it.
</p></dd>
<dt><samp>1</samp></dt>
<dt><samp>always</samp></dt>
<dd><p>Always write it.
</p></dd>
</dl>
</dd>
</dl>
<a name="png"></a>
<h3 class="section">17.10 png<span class="pull-right"><a class="anchor hidden-xs" href="#png" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-png" aria-hidden="true">TOC</a></span></h3>
<p>PNG image encoder.
</p>
<a name="Private-options-1"></a>
<h4 class="subsection">17.10.1 Private options<span class="pull-right"><a class="anchor hidden-xs" href="#Private-options-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Private-options-1" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>dpi <var>integer</var></samp></dt>
<dd><p>Set physical density of pixels, in dots per inch, unset by default
</p></dd>
<dt><samp>dpm <var>integer</var></samp></dt>
<dd><p>Set physical density of pixels, in dots per meter, unset by default
</p></dd>
</dl>
<a name="ProRes"></a>
<h3 class="section">17.11 ProRes<span class="pull-right"><a class="anchor hidden-xs" href="#ProRes" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ProRes" aria-hidden="true">TOC</a></span></h3>
<p>Apple ProRes encoder.
</p>
<p>FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder.
The used encoder can be chosen with the <code>-vcodec</code> option.
</p>
<a name="Private-Options-for-prores_002dks"></a>
<h4 class="subsection">17.11.1 Private Options for prores-ks<span class="pull-right"><a class="anchor hidden-xs" href="#Private-Options-for-prores_002dks" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Private-Options-for-prores_002dks" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>profile <var>integer</var></samp></dt>
<dd><p>Select the ProRes profile to encode
</p><dl compact="compact">
<dt>‘<samp>proxy</samp>’</dt>
<dt>‘<samp>lt</samp>’</dt>
<dt>‘<samp>standard</samp>’</dt>
<dt>‘<samp>hq</samp>’</dt>
<dt>‘<samp>4444</samp>’</dt>
</dl>
</dd>
<dt><samp>quant_mat <var>integer</var></samp></dt>
<dd><p>Select quantization matrix.
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dt>‘<samp>default</samp>’</dt>
<dt>‘<samp>proxy</samp>’</dt>
<dt>‘<samp>lt</samp>’</dt>
<dt>‘<samp>standard</samp>’</dt>
<dt>‘<samp>hq</samp>’</dt>
</dl>
<p>If set to <var>auto</var>, the matrix matching the profile will be picked.
If not set, the matrix providing the highest quality, <var>default</var>, will be
picked.
</p>
</dd>
<dt><samp>bits_per_mb <var>integer</var></samp></dt>
<dd><p>How many bits to allot for coding one macroblock. Different profiles use
between 200 and 2400 bits per macroblock, the maximum is 8000.
</p>
</dd>
<dt><samp>mbs_per_slice <var>integer</var></samp></dt>
<dd><p>Number of macroblocks in each slice (1-8); the default value (8)
should be good in almost all situations.
</p>
</dd>
<dt><samp>vendor <var>string</var></samp></dt>
<dd><p>Override the 4-byte vendor ID.
A custom vendor ID like <var>apl0</var> would claim the stream was produced by
the Apple encoder.
</p>
</dd>
<dt><samp>alpha_bits <var>integer</var></samp></dt>
<dd><p>Specify number of bits for alpha component.
Possible values are <var>0</var>, <var>8</var> and <var>16</var>.
Use <var>0</var> to disable alpha plane coding.
</p>
</dd>
</dl>
<a name="Speed-considerations"></a>
<h4 class="subsection">17.11.2 Speed considerations<span class="pull-right"><a class="anchor hidden-xs" href="#Speed-considerations" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Speed-considerations" aria-hidden="true">TOC</a></span></h4>
<p>In the default mode of operation the encoder has to honor frame constraints
(i.e. not produce frames with size bigger than requested) while still making
output picture as good as possible.
A frame containing a lot of small details is harder to compress and the encoder
would spend more time searching for appropriate quantizers for each slice.
</p>
<p>Setting a higher <samp>bits_per_mb</samp> limit will improve the speed.
</p>
<p>For the fastest encoding speed set the <samp>qscale</samp> parameter (4 is the
recommended value) and do not set a size constraint.
</p>
<a name="libkvazaar"></a>
<h3 class="section">17.12 libkvazaar<span class="pull-right"><a class="anchor hidden-xs" href="#libkvazaar" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libkvazaar" aria-hidden="true">TOC</a></span></h3>
<p>Kvazaar H.265/HEVC encoder.
</p>
<p>Requires the presence of the libkvazaar headers and library during
configuration. You need to explicitly configure the build with
<samp>--enable-libkvazaar</samp>.
</p>
<a name="Options-28"></a>
<h4 class="subsection">17.12.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-28" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-28" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>b</samp></dt>
<dd><p>Set target video bitrate in bit/s and enable rate control.
</p>
</dd>
<dt><samp>threads</samp></dt>
<dd><p>Set number of encoding threads.
</p>
</dd>
<dt><samp>kvazaar-params</samp></dt>
<dd><p>Set kvazaar parameters as a list of <var>name</var>=<var>value</var> pairs separated
by commas (,). See kvazaar documentation for a list of options.
</p>
</dd>
</dl>
<a name="Subtitles-Encoders"></a>
<h2 class="chapter">18 Subtitles Encoders<span class="pull-right"><a class="anchor hidden-xs" href="#Subtitles-Encoders" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Subtitles-Encoders" aria-hidden="true">TOC</a></span></h2>
<a name="dvdsub-1"></a>
<h3 class="section">18.1 dvdsub<span class="pull-right"><a class="anchor hidden-xs" href="#dvdsub-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dvdsub-1" aria-hidden="true">TOC</a></span></h3>
<p>This codec encodes the bitmap subtitle format that is used in DVDs.
Typically they are stored in VOBSUB file pairs (*.idx + *.sub),
and they can also be used in Matroska files.
</p>
<a name="Options-29"></a>
<h4 class="subsection">18.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-29" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-29" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>even_rows_fix</samp></dt>
<dd><p>When set to 1, enable a work-around that makes the number of pixel rows
even in all subtitles. This fixes a problem with some players that
cut off the bottom row if the number is odd. The work-around just adds
a fully transparent row if needed. The overhead is low, typically
one byte per subtitle on average.
</p>
<p>By default, this work-around is disabled.
</p></dd>
</dl>
<a name="Bitstream-Filters"></a>
<h2 class="chapter">19 Bitstream Filters<span class="pull-right"><a class="anchor hidden-xs" href="#Bitstream-Filters" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Bitstream-Filters" aria-hidden="true">TOC</a></span></h2>
<p>When you configure your FFmpeg build, all the supported bitstream
filters are enabled by default. You can list all available ones using
the configure option <code>--list-bsfs</code>.
</p>
<p>You can disable all the bitstream filters using the configure option
<code>--disable-bsfs</code>, and selectively enable any bitstream filter using
the option <code>--enable-bsf=BSF</code>, or you can disable a particular
bitstream filter using the option <code>--disable-bsf=BSF</code>.
</p>
<p>The option <code>-bsfs</code> of the ff* tools will display the list of
all the supported bitstream filters included in your build.
</p>
<p>The ff* tools have a -bsf option applied per stream, taking a
comma-separated list of filters, whose parameters follow the filter
name after a ’=’.
</p>
<div class="example">
<pre class="example">ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT
</pre></div>
<p>Below is a description of the currently available bitstream filters,
with their parameters, if any.
</p>
<a name="aac_005fadtstoasc"></a>
<h3 class="section">19.1 aac_adtstoasc<span class="pull-right"><a class="anchor hidden-xs" href="#aac_005fadtstoasc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aac_005fadtstoasc" aria-hidden="true">TOC</a></span></h3>
<p>Convert MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration
bitstream filter.
</p>
<p>This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
ADTS header and removes the ADTS header.
</p>
<p>This is required for example when copying an AAC stream from a raw
ADTS AAC container to a FLV or a MOV/MP4 file.
</p>
<a name="chomp"></a>
<h3 class="section">19.2 chomp<span class="pull-right"><a class="anchor hidden-xs" href="#chomp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-chomp" aria-hidden="true">TOC</a></span></h3>
<p>Remove zero padding at the end of a packet.
</p>
<a name="dump_005fextra"></a>
<h3 class="section">19.3 dump_extra<span class="pull-right"><a class="anchor hidden-xs" href="#dump_005fextra" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dump_005fextra" aria-hidden="true">TOC</a></span></h3>
<p>Add extradata to the beginning of the filtered packets.
</p>
<p>The additional argument specifies which packets should be filtered.
It accepts the values:
</p><dl compact="compact">
<dt>‘<samp>a</samp>’</dt>
<dd><p>add extradata to all key packets, but only if <var>local_header</var> is
set in the <samp>flags2</samp> codec context field
</p>
</dd>
<dt>‘<samp>k</samp>’</dt>
<dd><p>add extradata to all key packets
</p>
</dd>
<dt>‘<samp>e</samp>’</dt>
<dd><p>add extradata to all packets
</p></dd>
</dl>
<p>If not specified it is assumed ‘<samp>k</samp>’.
</p>
<p>For example the following <code>ffmpeg</code> command forces a global
header (thus disabling individual packet headers) in the H.264 packets
generated by the <code>libx264</code> encoder, but corrects them by adding
the header stored in extradata to the key packets:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
</pre></div>
<a name="h264_005fmp4toannexb"></a>
<h3 class="section">19.4 h264_mp4toannexb<span class="pull-right"><a class="anchor hidden-xs" href="#h264_005fmp4toannexb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-h264_005fmp4toannexb" aria-hidden="true">TOC</a></span></h3>
<p>Convert an H.264 bitstream from length prefixed mode to start code
prefixed mode (as defined in the Annex B of the ITU-T H.264
specification).
</p>
<p>This is required by some streaming formats, typically the MPEG-2
transport stream format ("mpegts").
</p>
<p>For example to remux an MP4 file containing an H.264 stream to mpegts
format with <code>ffmpeg</code>, you can use the command:
</p>
<div class="example">
<pre class="example">ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts
</pre></div>
<a name="imxdump"></a>
<h3 class="section">19.5 imxdump<span class="pull-right"><a class="anchor hidden-xs" href="#imxdump" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-imxdump" aria-hidden="true">TOC</a></span></h3>
<p>Modifies the bitstream to fit in MOV and to be usable by the Final Cut
Pro decoder. This filter only applies to the mpeg2video codec, and is
likely not needed for Final Cut Pro 7 and newer with the appropriate
<samp>-tag:v</samp>.
</p>
<p>For example, to remux 30 MB/sec NTSC IMX to MOV:
</p>
<div class="example">
<pre class="example">ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov
</pre></div>
<a name="mjpeg2jpeg"></a>
<h3 class="section">19.6 mjpeg2jpeg<span class="pull-right"><a class="anchor hidden-xs" href="#mjpeg2jpeg" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mjpeg2jpeg" aria-hidden="true">TOC</a></span></h3>
<p>Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
</p>
<p>MJPEG is a video codec wherein each video frame is essentially a
JPEG image. The individual frames can be extracted without loss,
e.g. by
</p>
<div class="example">
<pre class="example">ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
</pre></div>
<p>Unfortunately, these chunks are incomplete JPEG images, because
they lack the DHT segment required for decoding. Quoting from
<a href="http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml">http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml</a>:
</p>
<p>Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
commented that "MJPEG, or at least the MJPEG in AVIs having the
MJPG fourcc, is restricted JPEG with a fixed – and *omitted* –
Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
and it must use basic Huffman encoding, not arithmetic or
progressive. . . . You can indeed extract the MJPEG frames and
decode them with a regular JPEG decoder, but you have to prepend
the DHT segment to them, or else the decoder won’t have any idea
how to decompress the data. The exact table necessary is given in
the OpenDML spec."
</p>
<p>This bitstream filter patches the header of frames extracted from an MJPEG
stream (carrying the AVI1 header ID and lacking a DHT segment) to
produce fully qualified JPEG images.
</p>
<div class="example">
<pre class="example">ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
exiftran -i -9 frame*.jpg
ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
</pre></div>
<a name="mjpega_005fdump_005fheader"></a>
<h3 class="section">19.7 mjpega_dump_header<span class="pull-right"><a class="anchor hidden-xs" href="#mjpega_005fdump_005fheader" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mjpega_005fdump_005fheader" aria-hidden="true">TOC</a></span></h3>
<a name="movsub"></a>
<h3 class="section">19.8 movsub<span class="pull-right"><a class="anchor hidden-xs" href="#movsub" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-movsub" aria-hidden="true">TOC</a></span></h3>
<a name="mp3_005fheader_005fdecompress"></a>
<h3 class="section">19.9 mp3_header_decompress<span class="pull-right"><a class="anchor hidden-xs" href="#mp3_005fheader_005fdecompress" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mp3_005fheader_005fdecompress" aria-hidden="true">TOC</a></span></h3>
<a name="mpeg4_005funpack_005fbframes"></a>
<h3 class="section">19.10 mpeg4_unpack_bframes<span class="pull-right"><a class="anchor hidden-xs" href="#mpeg4_005funpack_005fbframes" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mpeg4_005funpack_005fbframes" aria-hidden="true">TOC</a></span></h3>
<p>Unpack DivX-style packed B-frames.
</p>
<p>DivX-style packed B-frames are not valid MPEG-4 and were only a
workaround for the broken Video for Windows subsystem.
They use more space, can cause minor AV sync issues, require more
CPU power to decode (unless the player has some decoded picture queue
to compensate the 2,0,2,0 frame per packet style) and cause
trouble if copied into a standard container like mp4 or mpeg-ps/ts,
because MPEG-4 decoders may not be able to decode them, since they are
not valid MPEG-4.
</p>
<p>For example to fix an AVI file containing an MPEG-4 stream with
DivX-style packed B-frames using <code>ffmpeg</code>, you can use the command:
</p>
<div class="example">
<pre class="example">ffmpeg -i INPUT.avi -codec copy -bsf:v mpeg4_unpack_bframes OUTPUT.avi
</pre></div>
<a name="noise"></a>
<h3 class="section">19.11 noise<span class="pull-right"><a class="anchor hidden-xs" href="#noise" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-noise" aria-hidden="true">TOC</a></span></h3>
<p>Damages the contents of packets without damaging the container. Can be
used for fuzzing or testing error resilience/concealment.
</p>
<p>Parameters:
A numeral string, whose value is related to how often output bytes will
be modified. Therefore, values below or equal to 0 are forbidden, and
the lower the more frequent bytes will be modified, with 1 meaning
every byte is modified.
</p>
<div class="example">
<pre class="example">ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv
</pre></div>
<p>applies the modification to every byte.
</p>
<a name="remove_005fextra"></a>
<h3 class="section">19.12 remove_extra<span class="pull-right"><a class="anchor hidden-xs" href="#remove_005fextra" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-remove_005fextra" aria-hidden="true">TOC</a></span></h3>
<a name="Format-Options"></a>
<h2 class="chapter">20 Format Options<span class="pull-right"><a class="anchor hidden-xs" href="#Format-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Format-Options" aria-hidden="true">TOC</a></span></h2>
<p>The libavformat library provides some generic global options, which
can be set on all the muxers and demuxers. In addition each muxer or
demuxer may support so-called private options, which are specific for
that component.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools, or by setting the value explicitly in the
<code>AVFormatContext</code> options or using the <samp>libavutil/opt.h</samp> API
for programmatic use.
</p>
<p>The list of supported options follows:
</p>
<dl compact="compact">
<dt><samp>avioflags <var>flags</var> (<em>input/output</em>)</samp></dt>
<dd><p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>direct</samp>’</dt>
<dd><p>Reduce buffering.
</p></dd>
</dl>
</dd>
<dt><samp>probesize <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Set probing size in bytes, i.e. the size of the data to analyze to get
stream information. A higher value will enable detecting more
information in case it is dispersed into the stream, but will increase
latency. Must be an integer not lesser than 32. It is 5000000 by default.
</p>
</dd>
<dt><samp>packetsize <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Set packet size.
</p>
</dd>
<dt><samp>fflags <var>flags</var> (<em>input/output</em>)</samp></dt>
<dd><p>Set format flags.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>ignidx</samp>’</dt>
<dd><p>Ignore index.
</p></dd>
<dt>‘<samp>fastseek</samp>’</dt>
<dd><p>Enable fast, but inaccurate seeks for some formats.
</p></dd>
<dt>‘<samp>genpts</samp>’</dt>
<dd><p>Generate PTS.
</p></dd>
<dt>‘<samp>nofillin</samp>’</dt>
<dd><p>Do not fill in missing values that can be exactly calculated.
</p></dd>
<dt>‘<samp>noparse</samp>’</dt>
<dd><p>Disable AVParsers, this needs <code>+nofillin</code> too.
</p></dd>
<dt>‘<samp>igndts</samp>’</dt>
<dd><p>Ignore DTS.
</p></dd>
<dt>‘<samp>discardcorrupt</samp>’</dt>
<dd><p>Discard corrupted frames.
</p></dd>
<dt>‘<samp>sortdts</samp>’</dt>
<dd><p>Try to interleave output packets by DTS.
</p></dd>
<dt>‘<samp>keepside</samp>’</dt>
<dd><p>Do not merge side data.
</p></dd>
<dt>‘<samp>latm</samp>’</dt>
<dd><p>Enable RTP MP4A-LATM payload.
</p></dd>
<dt>‘<samp>nobuffer</samp>’</dt>
<dd><p>Reduce the latency introduced by optional buffering
</p></dd>
<dt>‘<samp>bitexact</samp>’</dt>
<dd><p>Only write platform-, build- and time-independent data.
This ensures that file and data checksums are reproducible and match between
platforms. Its primary use is for regression testing.
</p></dd>
</dl>
</dd>
<dt><samp>seek2any <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Allow seeking to non-keyframes on demuxer level when supported if set to 1.
Default is 0.
</p>
</dd>
<dt><samp>analyzeduration <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Specify how many microseconds are analyzed to probe the input. A
higher value will enable detecting more accurate information, but will
increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
</p>
</dd>
<dt><samp>cryptokey <var>hexadecimal string</var> (<em>input</em>)</samp></dt>
<dd><p>Set decryption key.
</p>
</dd>
<dt><samp>indexmem <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Set max memory used for timestamp index (per stream).
</p>
</dd>
<dt><samp>rtbufsize <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Set max memory used for buffering real-time frames.
</p>
</dd>
<dt><samp>fdebug <var>flags</var> (<em>input/output</em>)</samp></dt>
<dd><p>Print specific debug info.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>ts</samp>’</dt>
</dl>
</dd>
<dt><samp>max_delay <var>integer</var> (<em>input/output</em>)</samp></dt>
<dd><p>Set maximum muxing or demuxing delay in microseconds.
</p>
</dd>
<dt><samp>fpsprobesize <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Set number of frames used to probe fps.
</p>
</dd>
<dt><samp>audio_preload <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Set microseconds by which audio packets should be interleaved earlier.
</p>
</dd>
<dt><samp>chunk_duration <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Set microseconds for each chunk.
</p>
</dd>
<dt><samp>chunk_size <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Set size in bytes for each chunk.
</p>
</dd>
<dt><samp>err_detect, f_err_detect <var>flags</var> (<em>input</em>)</samp></dt>
<dd><p>Set error detection flags. <code>f_err_detect</code> is deprecated and
should be used only via the <code>ffmpeg</code> tool.
</p>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>crccheck</samp>’</dt>
<dd><p>Verify embedded CRCs.
</p></dd>
<dt>‘<samp>bitstream</samp>’</dt>
<dd><p>Detect bitstream specification deviations.
</p></dd>
<dt>‘<samp>buffer</samp>’</dt>
<dd><p>Detect improper bitstream length.
</p></dd>
<dt>‘<samp>explode</samp>’</dt>
<dd><p>Abort decoding on minor error detection.
</p></dd>
<dt>‘<samp>careful</samp>’</dt>
<dd><p>Consider things that violate the spec and have not been seen in the
wild as errors.
</p></dd>
<dt>‘<samp>compliant</samp>’</dt>
<dd><p>Consider all spec non compliancies as errors.
</p></dd>
<dt>‘<samp>aggressive</samp>’</dt>
<dd><p>Consider things that a sane encoder should not do as an error.
</p></dd>
</dl>
</dd>
<dt><samp>max_interleave_delta <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Set maximum buffering duration for interleaving. The duration is
expressed in microseconds, and defaults to 1000000 (1 second).
</p>
<p>To ensure all the streams are interleaved correctly, libavformat will
wait until it has at least one packet for each stream before actually
writing any packets to the output file. When some streams are
"sparse" (i.e. there are large gaps between successive packets), this
can result in excessive buffering.
</p>
<p>This field specifies the maximum difference between the timestamps of the
first and the last packet in the muxing queue, above which libavformat
will output a packet regardless of whether it has queued a packet for all
the streams.
</p>
<p>If set to 0, libavformat will continue buffering packets until it has
a packet for each stream, regardless of the maximum timestamp
difference between the buffered packets.
</p>
</dd>
<dt><samp>use_wallclock_as_timestamps <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Use wallclock as timestamps.
</p>
</dd>
<dt><samp>avoid_negative_ts <var>integer</var> (<em>output</em>)</samp></dt>
<dd>
<p>Possible values:
</p><dl compact="compact">
<dt>‘<samp>make_non_negative</samp>’</dt>
<dd><p>Shift timestamps to make them non-negative.
Also note that this affects only leading negative timestamps, and not
non-monotonic negative timestamps.
</p></dd>
<dt>‘<samp>make_zero</samp>’</dt>
<dd><p>Shift timestamps so that the first timestamp is 0.
</p></dd>
<dt>‘<samp>auto (default)</samp>’</dt>
<dd><p>Enables shifting when required by the target format.
</p></dd>
<dt>‘<samp>disabled</samp>’</dt>
<dd><p>Disables shifting of timestamp.
</p></dd>
</dl>
<p>When shifting is enabled, all output timestamps are shifted by the
same amount. Audio, video, and subtitles desynching and relative
timestamp differences are preserved compared to how they would have
been without shifting.
</p>
</dd>
<dt><samp>skip_initial_bytes <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Set number of bytes to skip before reading header and frames if set to 1.
Default is 0.
</p>
</dd>
<dt><samp>correct_ts_overflow <var>integer</var> (<em>input</em>)</samp></dt>
<dd><p>Correct single timestamp overflows if set to 1. Default is 1.
</p>
</dd>
<dt><samp>flush_packets <var>integer</var> (<em>output</em>)</samp></dt>
<dd><p>Flush the underlying I/O stream after each packet. Default 1 enables it, and
has the effect of reducing the latency; 0 disables it and may slightly
increase performance in some cases.
</p>
</dd>
<dt><samp>output_ts_offset <var>offset</var> (<em>output</em>)</samp></dt>
<dd><p>Set the output time offset.
</p>
<p><var>offset</var> must be a time duration specification,
see <a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>.
</p>
<p>The offset is added by the muxer to the output timestamps.
</p>
<p>Specifying a positive offset means that the corresponding streams are
delayed bt the time duration specified in <var>offset</var>. Default value
is <code>0</code> (meaning that no offset is applied).
</p>
</dd>
<dt><samp>format_whitelist <var>list</var> (<em>input</em>)</samp></dt>
<dd><p>"," separated List of allowed demuxers. By default all are allowed.
</p>
</dd>
<dt><samp>dump_separator <var>string</var> (<em>input</em>)</samp></dt>
<dd><p>Separator used to separate the fields printed on the command line about the
Stream parameters.
For example to separate the fields with newlines and indention:
</p><div class="example">
<pre class="example">ffprobe -dump_separator "
" -i ~/videos/matrixbench_mpeg2.mpg
</pre></div>
</dd>
</dl>
<a name="Format-stream-specifiers"></a><a name="Format-stream-specifiers-1"></a>
<h3 class="section">20.1 Format stream specifiers<span class="pull-right"><a class="anchor hidden-xs" href="#Format-stream-specifiers-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Format-stream-specifiers-1" aria-hidden="true">TOC</a></span></h3>
<p>Format stream specifiers allow selection of one or more streams that
match specific properties.
</p>
<p>Possible forms of stream specifiers are:
</p><dl compact="compact">
<dt><samp><var>stream_index</var></samp></dt>
<dd><p>Matches the stream with this index.
</p>
</dd>
<dt><samp><var>stream_type</var>[:<var>stream_index</var>]</samp></dt>
<dd><p><var>stream_type</var> is one of following: ’v’ for video, ’a’ for audio,
’s’ for subtitle, ’d’ for data, and ’t’ for attachments. If
<var>stream_index</var> is given, then it matches the stream number
<var>stream_index</var> of this type. Otherwise, it matches all streams of
this type.
</p>
</dd>
<dt><samp>p:<var>program_id</var>[:<var>stream_index</var>]</samp></dt>
<dd><p>If <var>stream_index</var> is given, then it matches the stream with number
<var>stream_index</var> in the program with the id
<var>program_id</var>. Otherwise, it matches all streams in the program.
</p>
</dd>
<dt><samp>#<var>stream_id</var></samp></dt>
<dd><p>Matches the stream by a format-specific ID.
</p></dd>
</dl>
<p>The exact semantics of stream specifiers is defined by the
<code>avformat_match_stream_specifier()</code> function declared in the
<samp>libavformat/avformat.h</samp> header.
</p>
<a name="Demuxers"></a>
<h2 class="chapter">21 Demuxers<span class="pull-right"><a class="anchor hidden-xs" href="#Demuxers" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Demuxers" aria-hidden="true">TOC</a></span></h2>
<p>Demuxers are configured elements in FFmpeg that can read the
multimedia streams from a particular type of file.
</p>
<p>When you configure your FFmpeg build, all the supported demuxers
are enabled by default. You can list all available ones using the
configure option <code>--list-demuxers</code>.
</p>
<p>You can disable all the demuxers using the configure option
<code>--disable-demuxers</code>, and selectively enable a single demuxer with
the option <code>--enable-demuxer=<var>DEMUXER</var></code>, or disable it
with the option <code>--disable-demuxer=<var>DEMUXER</var></code>.
</p>
<p>The option <code>-formats</code> of the ff* tools will display the list of
enabled demuxers.
</p>
<p>The description of some of the currently available demuxers follows.
</p>
<a name="aa"></a>
<h3 class="section">21.1 aa<span class="pull-right"><a class="anchor hidden-xs" href="#aa" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aa" aria-hidden="true">TOC</a></span></h3>
<p>Audible Format 2, 3, and 4 demuxer.
</p>
<p>This demuxer is used to demux Audible Format 2, 3, and 4 (.aa) files.
</p>
<a name="applehttp"></a>
<h3 class="section">21.2 applehttp<span class="pull-right"><a class="anchor hidden-xs" href="#applehttp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-applehttp" aria-hidden="true">TOC</a></span></h3>
<p>Apple HTTP Live Streaming demuxer.
</p>
<p>This demuxer presents all AVStreams from all variant streams.
The id field is set to the bitrate variant index number. By setting
the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
the caller can decide which variant streams to actually receive.
The total bitrate of the variant that the stream belongs to is
available in a metadata key named "variant_bitrate".
</p>
<a name="apng"></a>
<h3 class="section">21.3 apng<span class="pull-right"><a class="anchor hidden-xs" href="#apng" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-apng" aria-hidden="true">TOC</a></span></h3>
<p>Animated Portable Network Graphics demuxer.
</p>
<p>This demuxer is used to demux APNG files.
All headers, but the PNG signature, up to (but not including) the first
fcTL chunk are transmitted as extradata.
Frames are then split as being all the chunks between two fcTL ones, or
between the last fcTL and IEND chunks.
</p>
<dl compact="compact">
<dt><samp>-ignore_loop <var>bool</var></samp></dt>
<dd><p>Ignore the loop variable in the file if set.
</p></dd>
<dt><samp>-max_fps <var>int</var></samp></dt>
<dd><p>Maximum framerate in frames per second (0 for no limit).
</p></dd>
<dt><samp>-default_fps <var>int</var></samp></dt>
<dd><p>Default framerate in frames per second when none is specified in the file
(0 meaning as fast as possible).
</p></dd>
</dl>
<a name="asf"></a>
<h3 class="section">21.4 asf<span class="pull-right"><a class="anchor hidden-xs" href="#asf" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-asf" aria-hidden="true">TOC</a></span></h3>
<p>Advanced Systems Format demuxer.
</p>
<p>This demuxer is used to demux ASF files and MMS network streams.
</p>
<dl compact="compact">
<dt><samp>-no_resync_search <var>bool</var></samp></dt>
<dd><p>Do not try to resynchronize by looking for a certain optional start code.
</p></dd>
</dl>
<a name="concat"></a><a name="concat-1"></a>
<h3 class="section">21.5 concat<span class="pull-right"><a class="anchor hidden-xs" href="#concat-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-concat-1" aria-hidden="true">TOC</a></span></h3>
<p>Virtual concatenation script demuxer.
</p>
<p>This demuxer reads a list of files and other directives from a text file and
demuxes them one after the other, as if all their packet had been muxed
together.
</p>
<p>The timestamps in the files are adjusted so that the first file starts at 0
and each next file starts where the previous one finishes. Note that it is
done globally and may cause gaps if all streams do not have exactly the same
length.
</p>
<p>All files must have the same streams (same codecs, same time base, etc.).
</p>
<p>The duration of each file is used to adjust the timestamps of the next file:
if the duration is incorrect (because it was computed using the bit-rate or
because the file is truncated, for example), it can cause artifacts. The
<code>duration</code> directive can be used to override the duration stored in
each file.
</p>
<a name="Syntax-1"></a>
<h4 class="subsection">21.5.1 Syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Syntax-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Syntax-1" aria-hidden="true">TOC</a></span></h4>
<p>The script is a text file in extended-ASCII, with one directive per line.
Empty lines, leading spaces and lines starting with ’#’ are ignored. The
following directive is recognized:
</p>
<dl compact="compact">
<dt><samp><code>file <var>path</var></code></samp></dt>
<dd><p>Path to a file to read; special characters and spaces must be escaped with
backslash or single quotes.
</p>
<p>All subsequent file-related directives apply to that file.
</p>
</dd>
<dt><samp><code>ffconcat version 1.0</code></samp></dt>
<dd><p>Identify the script type and version. It also sets the <samp>safe</samp> option
to 1 if it was to its default -1.
</p>
<p>To make FFmpeg recognize the format automatically, this directive must
appears exactly as is (no extra space or byte-order-mark) on the very first
line of the script.
</p>
</dd>
<dt><samp><code>duration <var>dur</var></code></samp></dt>
<dd><p>Duration of the file. This information can be specified from the file;
specifying it here may be more efficient or help if the information from the
file is not available or accurate.
</p>
<p>If the duration is set for all files, then it is possible to seek in the
whole concatenated video.
</p>
</dd>
<dt><samp><code>inpoint <var>timestamp</var></code></samp></dt>
<dd><p>In point of the file. When the demuxer opens the file it instantly seeks to the
specified timestamp. Seeking is done so that all streams can be presented
successfully at In point.
</p>
<p>This directive works best with intra frame codecs, because for non-intra frame
ones you will usually get extra packets before the actual In point and the
decoded content will most likely contain frames before In point too.
</p>
<p>For each file, packets before the file In point will have timestamps less than
the calculated start timestamp of the file (negative in case of the first
file), and the duration of the files (if not specified by the <code>duration</code>
directive) will be reduced based on their specified In point.
</p>
<p>Because of potential packets before the specified In point, packet timestamps
may overlap between two concatenated files.
</p>
</dd>
<dt><samp><code>outpoint <var>timestamp</var></code></samp></dt>
<dd><p>Out point of the file. When the demuxer reaches the specified decoding
timestamp in any of the streams, it handles it as an end of file condition and
skips the current and all the remaining packets from all streams.
</p>
<p>Out point is exclusive, which means that the demuxer will not output packets
with a decoding timestamp greater or equal to Out point.
</p>
<p>This directive works best with intra frame codecs and formats where all streams
are tightly interleaved. For non-intra frame codecs you will usually get
additional packets with presentation timestamp after Out point therefore the
decoded content will most likely contain frames after Out point too. If your
streams are not tightly interleaved you may not get all the packets from all
streams before Out point and you may only will be able to decode the earliest
stream until Out point.
</p>
<p>The duration of the files (if not specified by the <code>duration</code>
directive) will be reduced based on their specified Out point.
</p>
</dd>
<dt><samp><code>file_packet_metadata <var>key=value</var></code></samp></dt>
<dd><p>Metadata of the packets of the file. The specified metadata will be set for
each file packet. You can specify this directive multiple times to add multiple
metadata entries.
</p>
</dd>
<dt><samp><code>stream</code></samp></dt>
<dd><p>Introduce a stream in the virtual file.
All subsequent stream-related directives apply to the last introduced
stream.
Some streams properties must be set in order to allow identifying the
matching streams in the subfiles.
If no streams are defined in the script, the streams from the first file are
copied.
</p>
</dd>
<dt><samp><code>exact_stream_id <var>id</var></code></samp></dt>
<dd><p>Set the id of the stream.
If this directive is given, the string with the corresponding id in the
subfiles will be used.
This is especially useful for MPEG-PS (VOB) files, where the order of the
streams is not reliable.
</p>
</dd>
</dl>
<a name="Options-30"></a>
<h4 class="subsection">21.5.2 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-30" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-30" aria-hidden="true">TOC</a></span></h4>
<p>This demuxer accepts the following option:
</p>
<dl compact="compact">
<dt><samp>safe</samp></dt>
<dd><p>If set to 1, reject unsafe file paths. A file path is considered safe if it
does not contain a protocol specification and is relative and all components
only contain characters from the portable character set (letters, digits,
period, underscore and hyphen) and have no period at the beginning of a
component.
</p>
<p>If set to 0, any file name is accepted.
</p>
<p>The default is -1, it is equivalent to 1 if the format was automatically
probed and 0 otherwise.
</p>
</dd>
<dt><samp>auto_convert</samp></dt>
<dd><p>If set to 1, try to perform automatic conversions on packet data to make the
streams concatenable.
The default is 1.
</p>
<p>Currently, the only conversion is adding the h264_mp4toannexb bitstream
filter to H.264 streams in MP4 format. This is necessary in particular if
there are resolution changes.
</p>
</dd>
</dl>
<a name="flv"></a>
<h3 class="section">21.6 flv<span class="pull-right"><a class="anchor hidden-xs" href="#flv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-flv" aria-hidden="true">TOC</a></span></h3>
<p>Adobe Flash Video Format demuxer.
</p>
<p>This demuxer is used to demux FLV files and RTMP network streams.
</p>
<dl compact="compact">
<dt><samp>-flv_metadata <var>bool</var></samp></dt>
<dd><p>Allocate the streams according to the onMetaData array content.
</p></dd>
</dl>
<a name="libgme"></a>
<h3 class="section">21.7 libgme<span class="pull-right"><a class="anchor hidden-xs" href="#libgme" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libgme" aria-hidden="true">TOC</a></span></h3>
<p>The Game Music Emu library is a collection of video game music file emulators.
</p>
<p>See <a href="http://code.google.com/p/game-music-emu/">http://code.google.com/p/game-music-emu/</a> for more information.
</p>
<p>Some files have multiple tracks. The demuxer will pick the first track by
default. The <samp>track_index</samp> option can be used to select a different
track. Track indexes start at 0. The demuxer exports the number of tracks as
<var>tracks</var> meta data entry.
</p>
<p>For very large files, the <samp>max_size</samp> option may have to be adjusted.
</p>
<a name="libquvi"></a>
<h3 class="section">21.8 libquvi<span class="pull-right"><a class="anchor hidden-xs" href="#libquvi" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libquvi" aria-hidden="true">TOC</a></span></h3>
<p>Play media from Internet services using the quvi project.
</p>
<p>The demuxer accepts a <samp>format</samp> option to request a specific quality. It
is by default set to <var>best</var>.
</p>
<p>See <a href="http://quvi.sourceforge.net/">http://quvi.sourceforge.net/</a> for more information.
</p>
<p>FFmpeg needs to be built with <code>--enable-libquvi</code> for this demuxer to be
enabled.
</p>
<a name="gif-1"></a>
<h3 class="section">21.9 gif<span class="pull-right"><a class="anchor hidden-xs" href="#gif-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-gif-1" aria-hidden="true">TOC</a></span></h3>
<p>Animated GIF demuxer.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>min_delay</samp></dt>
<dd><p>Set the minimum valid delay between frames in hundredths of seconds.
Range is 0 to 6000. Default value is 2.
</p>
</dd>
<dt><samp>max_gif_delay</samp></dt>
<dd><p>Set the maximum valid delay between frames in hundredth of seconds.
Range is 0 to 65535. Default value is 65535 (nearly eleven minutes),
the maximum value allowed by the specification.
</p>
</dd>
<dt><samp>default_delay</samp></dt>
<dd><p>Set the default delay between frames in hundredths of seconds.
Range is 0 to 6000. Default value is 10.
</p>
</dd>
<dt><samp>ignore_loop</samp></dt>
<dd><p>GIF files can contain information to loop a certain number of times (or
infinitely). If <samp>ignore_loop</samp> is set to 1, then the loop setting
from the input will be ignored and looping will not occur. If set to 0,
then looping will occur and will cycle the number of times according to
the GIF. Default value is 1.
</p></dd>
</dl>
<p>For example, with the overlay filter, place an infinitely looping GIF
over another video:
</p><div class="example">
<pre class="example">ffmpeg -i input.mp4 -ignore_loop 0 -i input.gif -filter_complex overlay=shortest=1 out.mkv
</pre></div>
<p>Note that in the above example the shortest option for overlay filter is
used to end the output video at the length of the shortest input file,
which in this case is <samp>input.mp4</samp> as the GIF in this example loops
infinitely.
</p>
<a name="image2-1"></a>
<h3 class="section">21.10 image2<span class="pull-right"><a class="anchor hidden-xs" href="#image2-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-image2-1" aria-hidden="true">TOC</a></span></h3>
<p>Image file demuxer.
</p>
<p>This demuxer reads from a list of image files specified by a pattern.
The syntax and meaning of the pattern is specified by the
option <var>pattern_type</var>.
</p>
<p>The pattern may contain a suffix which is used to automatically
determine the format of the images contained in the files.
</p>
<p>The size, the pixel format, and the format of each image must be the
same for all the files in the sequence.
</p>
<p>This demuxer accepts the following options:
</p><dl compact="compact">
<dt><samp>framerate</samp></dt>
<dd><p>Set the frame rate for the video stream. It defaults to 25.
</p></dd>
<dt><samp>loop</samp></dt>
<dd><p>If set to 1, loop over the input. Default value is 0.
</p></dd>
<dt><samp>pattern_type</samp></dt>
<dd><p>Select the pattern type used to interpret the provided filename.
</p>
<p><var>pattern_type</var> accepts one of the following values.
</p><dl compact="compact">
<dt><samp>none</samp></dt>
<dd><p>Disable pattern matching, therefore the video will only contain the specified
image. You should use this option if you do not want to create sequences from
multiple images and your filenames may contain special pattern characters.
</p></dd>
<dt><samp>sequence</samp></dt>
<dd><p>Select a sequence pattern type, used to specify a sequence of files
indexed by sequential numbers.
</p>
<p>A sequence pattern may contain the string "%d" or "%0<var>N</var>d", which
specifies the position of the characters representing a sequential
number in each filename matched by the pattern. If the form
"%d0<var>N</var>d" is used, the string representing the number in each
filename is 0-padded and <var>N</var> is the total number of 0-padded
digits representing the number. The literal character ’%’ can be
specified in the pattern with the string "%%".
</p>
<p>If the sequence pattern contains "%d" or "%0<var>N</var>d", the first filename of
the file list specified by the pattern must contain a number
inclusively contained between <var>start_number</var> and
<var>start_number</var>+<var>start_number_range</var>-1, and all the following
numbers must be sequential.
</p>
<p>For example the pattern "img-%03d.bmp" will match a sequence of
filenames of the form <samp>img-001.bmp</samp>, <samp>img-002.bmp</samp>, ...,
<samp>img-010.bmp</samp>, etc.; the pattern "i%%m%%g-%d.jpg" will match a
sequence of filenames of the form <samp>i%m%g-1.jpg</samp>,
<samp>i%m%g-2.jpg</samp>, ..., <samp>i%m%g-10.jpg</samp>, etc.
</p>
<p>Note that the pattern must not necessarily contain "%d" or
"%0<var>N</var>d", for example to convert a single image file
<samp>img.jpeg</samp> you can employ the command:
</p><div class="example">
<pre class="example">ffmpeg -i img.jpeg img.png
</pre></div>
</dd>
<dt><samp>glob</samp></dt>
<dd><p>Select a glob wildcard pattern type.
</p>
<p>The pattern is interpreted like a <code>glob()</code> pattern. This is only
selectable if libavformat was compiled with globbing support.
</p>
</dd>
<dt><samp>glob_sequence <em>(deprecated, will be removed)</em></samp></dt>
<dd><p>Select a mixed glob wildcard/sequence pattern.
</p>
<p>If your version of libavformat was compiled with globbing support, and
the provided pattern contains at least one glob meta character among
<code>%*?[]{}</code> that is preceded by an unescaped "%", the pattern is
interpreted like a <code>glob()</code> pattern, otherwise it is interpreted
like a sequence pattern.
</p>
<p>All glob special characters <code>%*?[]{}</code> must be prefixed
with "%". To escape a literal "%" you shall use "%%".
</p>
<p>For example the pattern <code>foo-%*.jpeg</code> will match all the
filenames prefixed by "foo-" and terminating with ".jpeg", and
<code>foo-%?%?%?.jpeg</code> will match all the filenames prefixed with
"foo-", followed by a sequence of three characters, and terminating
with ".jpeg".
</p>
<p>This pattern type is deprecated in favor of <var>glob</var> and
<var>sequence</var>.
</p></dd>
</dl>
<p>Default value is <var>glob_sequence</var>.
</p></dd>
<dt><samp>pixel_format</samp></dt>
<dd><p>Set the pixel format of the images to read. If not specified the pixel
format is guessed from the first image file in the sequence.
</p></dd>
<dt><samp>start_number</samp></dt>
<dd><p>Set the index of the file matched by the image file pattern to start
to read from. Default value is 0.
</p></dd>
<dt><samp>start_number_range</samp></dt>
<dd><p>Set the index interval range to check when looking for the first image
file in the sequence, starting from <var>start_number</var>. Default value
is 5.
</p></dd>
<dt><samp>ts_from_file</samp></dt>
<dd><p>If set to 1, will set frame timestamp to modification time of image file. Note
that monotonity of timestamps is not provided: images go in the same order as
without this option. Default value is 0.
If set to 2, will set frame timestamp to the modification time of the image file in
nanosecond precision.
</p></dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the video size of the images to read. If not specified the video
size is guessed from the first image file in the sequence.
</p></dd>
</dl>
<a name="Examples-5"></a>
<h4 class="subsection">21.10.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-5" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-5" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use <code>ffmpeg</code> for creating a video from the images in the file
sequence <samp>img-001.jpeg</samp>, <samp>img-002.jpeg</samp>, ..., assuming an
input frame rate of 10 frames per second:
<div class="example">
<pre class="example">ffmpeg -framerate 10 -i 'img-%03d.jpeg' out.mkv
</pre></div>
</li><li> As above, but start by reading from a file with index 100 in the sequence:
<div class="example">
<pre class="example">ffmpeg -framerate 10 -start_number 100 -i 'img-%03d.jpeg' out.mkv
</pre></div>
</li><li> Read images matching the "*.png" glob pattern , that is all the files
terminating with the ".png" suffix:
<div class="example">
<pre class="example">ffmpeg -framerate 10 -pattern_type glob -i "*.png" out.mkv
</pre></div>
</li></ul>
<a name="mov_002fmp4_002f3gp_002fQuicktme"></a>
<h3 class="section">21.11 mov/mp4/3gp/Quicktme<span class="pull-right"><a class="anchor hidden-xs" href="#mov_002fmp4_002f3gp_002fQuicktme" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mov_002fmp4_002f3gp_002fQuicktme" aria-hidden="true">TOC</a></span></h3>
<p>Quicktime / MP4 demuxer.
</p>
<p>This demuxer accepts the following options:
</p><dl compact="compact">
<dt><samp>enable_drefs</samp></dt>
<dd><p>Enable loading of external tracks, disabled by default.
Enabling this can theoretically leak information in some use cases.
</p>
</dd>
<dt><samp>use_absolute_path</samp></dt>
<dd><p>Allows loading of external tracks via absolute paths, disabled by default.
Enabling this poses a security risk. It should only be enabled if the source
is known to be non malicious.
</p>
</dd>
</dl>
<a name="mpegts"></a>
<h3 class="section">21.12 mpegts<span class="pull-right"><a class="anchor hidden-xs" href="#mpegts" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mpegts" aria-hidden="true">TOC</a></span></h3>
<p>MPEG-2 transport stream demuxer.
</p>
<p>This demuxer accepts the following options:
</p><dl compact="compact">
<dt><samp>resync_size</samp></dt>
<dd><p>Set size limit for looking up a new synchronization. Default value is
65536.
</p>
</dd>
<dt><samp>fix_teletext_pts</samp></dt>
<dd><p>Override teletext packet PTS and DTS values with the timestamps calculated
from the PCR of the first program which the teletext stream is part of and is
not discarded. Default value is 1, set this option to 0 if you want your
teletext packet PTS and DTS values untouched.
</p>
</dd>
<dt><samp>ts_packetsize</samp></dt>
<dd><p>Output option carrying the raw packet size in bytes.
Show the detected raw packet size, cannot be set by the user.
</p>
</dd>
<dt><samp>scan_all_pmts</samp></dt>
<dd><p>Scan and combine all PMTs. The value is an integer with value from -1
to 1 (-1 means automatic setting, 1 means enabled, 0 means
disabled). Default value is -1.
</p></dd>
</dl>
<a name="rawvideo-1"></a>
<h3 class="section">21.13 rawvideo<span class="pull-right"><a class="anchor hidden-xs" href="#rawvideo-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rawvideo-1" aria-hidden="true">TOC</a></span></h3>
<p>Raw video demuxer.
</p>
<p>This demuxer allows one to read raw video data. Since there is no header
specifying the assumed video parameters, the user must specify them
in order to be able to decode the data correctly.
</p>
<p>This demuxer accepts the following options:
</p><dl compact="compact">
<dt><samp>framerate</samp></dt>
<dd><p>Set input video frame rate. Default value is 25.
</p>
</dd>
<dt><samp>pixel_format</samp></dt>
<dd><p>Set the input video pixel format. Default value is <code>yuv420p</code>.
</p>
</dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the input video size. This value must be specified explicitly.
</p></dd>
</dl>
<p>For example to read a rawvideo file <samp>input.raw</samp> with
<code>ffplay</code>, assuming a pixel format of <code>rgb24</code>, a video
size of <code>320x240</code>, and a frame rate of 10 images per second, use
the command:
</p><div class="example">
<pre class="example">ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 input.raw
</pre></div>
<a name="sbg"></a>
<h3 class="section">21.14 sbg<span class="pull-right"><a class="anchor hidden-xs" href="#sbg" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sbg" aria-hidden="true">TOC</a></span></h3>
<p>SBaGen script demuxer.
</p>
<p>This demuxer reads the script language used by SBaGen
<a href="http://uazu.net/sbagen/">http://uazu.net/sbagen/</a> to generate binaural beats sessions. A SBG
script looks like that:
</p><div class="example">
<pre class="example">-SE
a: 300-2.5/3 440+4.5/0
b: 300-2.5/0 440+4.5/3
off: -
NOW == a
+0:07:00 == b
+0:14:00 == a
+0:21:00 == b
+0:30:00 off
</pre></div>
<p>A SBG script can mix absolute and relative timestamps. If the script uses
either only absolute timestamps (including the script start time) or only
relative ones, then its layout is fixed, and the conversion is
straightforward. On the other hand, if the script mixes both kind of
timestamps, then the <var>NOW</var> reference for relative timestamps will be
taken from the current time of day at the time the script is read, and the
script layout will be frozen according to that reference. That means that if
the script is directly played, the actual times will match the absolute
timestamps up to the sound controller’s clock accuracy, but if the user
somehow pauses the playback or seeks, all times will be shifted accordingly.
</p>
<a name="tedcaptions"></a>
<h3 class="section">21.15 tedcaptions<span class="pull-right"><a class="anchor hidden-xs" href="#tedcaptions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tedcaptions" aria-hidden="true">TOC</a></span></h3>
<p>JSON captions used for <a href="http://www.ted.com/">TED Talks</a>.
</p>
<p>TED does not provide links to the captions, but they can be guessed from the
page. The file <samp>tools/bookmarklets.html</samp> from the FFmpeg source tree
contains a bookmarklet to expose them.
</p>
<p>This demuxer accepts the following option:
</p><dl compact="compact">
<dt><samp>start_time</samp></dt>
<dd><p>Set the start time of the TED talk, in milliseconds. The default is 15000
(15s). It is used to sync the captions with the downloadable videos, because
they include a 15s intro.
</p></dd>
</dl>
<p>Example: convert the captions to a format most players understand:
</p><div class="example">
<pre class="example">ffmpeg -i http://www.ted.com/talks/subtitles/id/1/lang/en talk1-en.srt
</pre></div>
<a name="Muxers"></a>
<h2 class="chapter">22 Muxers<span class="pull-right"><a class="anchor hidden-xs" href="#Muxers" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Muxers" aria-hidden="true">TOC</a></span></h2>
<p>Muxers are configured elements in FFmpeg which allow writing
multimedia streams to a particular type of file.
</p>
<p>When you configure your FFmpeg build, all the supported muxers
are enabled by default. You can list all available muxers using the
configure option <code>--list-muxers</code>.
</p>
<p>You can disable all the muxers with the configure option
<code>--disable-muxers</code> and selectively enable / disable single muxers
with the options <code>--enable-muxer=<var>MUXER</var></code> /
<code>--disable-muxer=<var>MUXER</var></code>.
</p>
<p>The option <code>-formats</code> of the ff* tools will display the list of
enabled muxers.
</p>
<p>A description of some of the currently available muxers follows.
</p>
<a name="aiff"></a><a name="aiff-1"></a>
<h3 class="section">22.1 aiff<span class="pull-right"><a class="anchor hidden-xs" href="#aiff-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aiff-1" aria-hidden="true">TOC</a></span></h3>
<p>Audio Interchange File Format muxer.
</p>
<a name="Options-31"></a>
<h4 class="subsection">22.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-31" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-31" aria-hidden="true">TOC</a></span></h4>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>write_id3v2</samp></dt>
<dd><p>Enable ID3v2 tags writing when set to 1. Default is 0 (disabled).
</p>
</dd>
<dt><samp>id3v2_version</samp></dt>
<dd><p>Select ID3v2 version to write. Currently only version 3 and 4 (aka.
ID3v2.3 and ID3v2.4) are supported. The default is version 4.
</p>
</dd>
</dl>
<a name="crc"></a><a name="crc-1"></a>
<h3 class="section">22.2 crc<span class="pull-right"><a class="anchor hidden-xs" href="#crc-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-crc-1" aria-hidden="true">TOC</a></span></h3>
<p>CRC (Cyclic Redundancy Check) testing format.
</p>
<p>This muxer computes and prints the Adler-32 CRC of all the input audio
and video frames. By default audio frames are converted to signed
16-bit raw audio and video frames to raw video before computing the
CRC.
</p>
<p>The output of the muxer consists of a single line of the form:
CRC=0x<var>CRC</var>, where <var>CRC</var> is a hexadecimal number 0-padded to
8 digits containing the CRC for all the decoded input frames.
</p>
<p>See also the <a href="#framecrc">framecrc</a> muxer.
</p>
<a name="Examples-6"></a>
<h4 class="subsection">22.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-6" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-6" aria-hidden="true">TOC</a></span></h4>
<p>For example to compute the CRC of the input, and store it in the file
<samp>out.crc</samp>:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f crc out.crc
</pre></div>
<p>You can print the CRC to stdout with the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f crc -
</pre></div>
<p>You can select the output format of each frame with <code>ffmpeg</code> by
specifying the audio and video codec and format. For example to
compute the CRC of the input audio converted to PCM unsigned 8-bit
and the input video converted to MPEG-2 video, use the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -
</pre></div>
<a name="framecrc"></a><a name="framecrc-1"></a>
<h3 class="section">22.3 framecrc<span class="pull-right"><a class="anchor hidden-xs" href="#framecrc-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-framecrc-1" aria-hidden="true">TOC</a></span></h3>
<p>Per-packet CRC (Cyclic Redundancy Check) testing format.
</p>
<p>This muxer computes and prints the Adler-32 CRC for each audio
and video packet. By default audio frames are converted to signed
16-bit raw audio and video frames to raw video before computing the
CRC.
</p>
<p>The output of the muxer consists of a line for each audio and video
packet of the form:
</p><div class="example">
<pre class="example"><var>stream_index</var>, <var>packet_dts</var>, <var>packet_pts</var>, <var>packet_duration</var>, <var>packet_size</var>, 0x<var>CRC</var>
</pre></div>
<p><var>CRC</var> is a hexadecimal number 0-padded to 8 digits containing the
CRC of the packet.
</p>
<a name="Examples-7"></a>
<h4 class="subsection">22.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-7" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-7" aria-hidden="true">TOC</a></span></h4>
<p>For example to compute the CRC of the audio and video frames in
<samp>INPUT</samp>, converted to raw audio and video packets, and store it
in the file <samp>out.crc</samp>:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f framecrc out.crc
</pre></div>
<p>To print the information to stdout, use the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f framecrc -
</pre></div>
<p>With <code>ffmpeg</code>, you can select the output format to which the
audio and video frames are encoded before computing the CRC for each
packet by specifying the audio and video codec. For example, to
compute the CRC of each decoded input audio frame converted to PCM
unsigned 8-bit and of each decoded input video frame converted to
MPEG-2 video, use the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -
</pre></div>
<p>See also the <a href="#crc">crc</a> muxer.
</p>
<a name="framemd5"></a><a name="framemd5-1"></a>
<h3 class="section">22.4 framemd5<span class="pull-right"><a class="anchor hidden-xs" href="#framemd5-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-framemd5-1" aria-hidden="true">TOC</a></span></h3>
<p>Per-packet MD5 testing format.
</p>
<p>This muxer computes and prints the MD5 hash for each audio
and video packet. By default audio frames are converted to signed
16-bit raw audio and video frames to raw video before computing the
hash.
</p>
<p>The output of the muxer consists of a line for each audio and video
packet of the form:
</p><div class="example">
<pre class="example"><var>stream_index</var>, <var>packet_dts</var>, <var>packet_pts</var>, <var>packet_duration</var>, <var>packet_size</var>, <var>MD5</var>
</pre></div>
<p><var>MD5</var> is a hexadecimal number representing the computed MD5 hash
for the packet.
</p>
<a name="Examples-8"></a>
<h4 class="subsection">22.4.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-8" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-8" aria-hidden="true">TOC</a></span></h4>
<p>For example to compute the MD5 of the audio and video frames in
<samp>INPUT</samp>, converted to raw audio and video packets, and store it
in the file <samp>out.md5</samp>:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f framemd5 out.md5
</pre></div>
<p>To print the information to stdout, use the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f framemd5 -
</pre></div>
<p>See also the <a href="#md5">md5</a> muxer.
</p>
<a name="gif"></a><a name="gif-2"></a>
<h3 class="section">22.5 gif<span class="pull-right"><a class="anchor hidden-xs" href="#gif-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-gif-2" aria-hidden="true">TOC</a></span></h3>
<p>Animated GIF muxer.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>loop</samp></dt>
<dd><p>Set the number of times to loop the output. Use <code>-1</code> for no loop, <code>0</code>
for looping indefinitely (default).
</p>
</dd>
<dt><samp>final_delay</samp></dt>
<dd><p>Force the delay (expressed in centiseconds) after the last frame. Each frame
ends with a delay until the next frame. The default is <code>-1</code>, which is a
special value to tell the muxer to re-use the previous delay. In case of a
loop, you might want to customize this value to mark a pause for instance.
</p></dd>
</dl>
<p>For example, to encode a gif looping 10 times, with a 5 seconds delay between
the loops:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -loop 10 -final_delay 500 out.gif
</pre></div>
<p>Note 1: if you wish to extract the frames in separate GIF files, you need to
force the <a href="#image2">image2</a> muxer:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -c:v gif -f image2 "out%d.gif"
</pre></div>
<p>Note 2: the GIF format has a very small time base: the delay between two frames
can not be smaller than one centi second.
</p>
<a name="hls"></a><a name="hls-1"></a>
<h3 class="section">22.6 hls<span class="pull-right"><a class="anchor hidden-xs" href="#hls-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hls-1" aria-hidden="true">TOC</a></span></h3>
<p>Apple HTTP Live Streaming muxer that segments MPEG-TS according to
the HTTP Live Streaming (HLS) specification.
</p>
<p>It creates a playlist file, and one or more segment files. The output filename
specifies the playlist filename.
</p>
<p>By default, the muxer creates a file for each segment produced. These files
have the same name as the playlist, followed by a sequential number and a
.ts extension.
</p>
<p>For example, to convert an input file with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i in.nut out.m3u8
</pre></div>
<p>This example will produce the playlist, <samp>out.m3u8</samp>, and segment files:
<samp>out0.ts</samp>, <samp>out1.ts</samp>, <samp>out2.ts</samp>, etc.
</p>
<p>See also the <a href="#segment">segment</a> muxer, which provides a more generic and
flexible implementation of a segmenter, and can be used to perform HLS
segmentation.
</p>
<a name="Options-32"></a>
<h4 class="subsection">22.6.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-32" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-32" aria-hidden="true">TOC</a></span></h4>
<p>This muxer supports the following options:
</p>
<dl compact="compact">
<dt><samp>hls_time <var>seconds</var></samp></dt>
<dd><p>Set the segment length in seconds. Default value is 2.
</p>
</dd>
<dt><samp>hls_list_size <var>size</var></samp></dt>
<dd><p>Set the maximum number of playlist entries. If set to 0 the list file
will contain all the segments. Default value is 5.
</p>
</dd>
<dt><samp>hls_ts_options <var>options_list</var></samp></dt>
<dd><p>Set output format options using a :-separated list of key=value
parameters. Values containing <code>:</code> special characters must be
escaped.
</p>
</dd>
<dt><samp>hls_wrap <var>wrap</var></samp></dt>
<dd><p>Set the number after which the segment filename number (the number
specified in each segment file) wraps. If set to 0 the number will be
never wrapped. Default value is 0.
</p>
<p>This option is useful to avoid to fill the disk with many segment
files, and limits the maximum number of segment files written to disk
to <var>wrap</var>.
</p>
</dd>
<dt><samp>start_number <var>number</var></samp></dt>
<dd><p>Start the playlist sequence number from <var>number</var>. Default value is
0.
</p>
</dd>
<dt><samp>hls_allow_cache <var>allowcache</var></samp></dt>
<dd><p>Explicitly set whether the client MAY (1) or MUST NOT (0) cache media segments.
</p>
</dd>
<dt><samp>hls_base_url <var>baseurl</var></samp></dt>
<dd><p>Append <var>baseurl</var> to every entry in the playlist.
Useful to generate playlists with absolute paths.
</p>
<p>Note that the playlist sequence number must be unique for each segment
and it is not to be confused with the segment filename sequence number
which can be cyclic, for example if the <samp>wrap</samp> option is
specified.
</p>
</dd>
<dt><samp>hls_segment_filename <var>filename</var></samp></dt>
<dd><p>Set the segment filename. Unless hls_flags single_file is set <var>filename</var>
is used as a string format with the segment number:
</p><div class="example">
<pre class="example">ffmpeg in.nut -hls_segment_filename 'file%03d.ts' out.m3u8
</pre></div>
<p>This example will produce the playlist, <samp>out.m3u8</samp>, and segment files:
<samp>file000.ts</samp>, <samp>file001.ts</samp>, <samp>file002.ts</samp>, etc.
</p>
</dd>
<dt><samp>hls_key_info_file <var>key_info_file</var></samp></dt>
<dd><p>Use the information in <var>key_info_file</var> for segment encryption. The first
line of <var>key_info_file</var> specifies the key URI written to the playlist. The
key URL is used to access the encryption key during playback. The second line
specifies the path to the key file used to obtain the key during the encryption
process. The key file is read as a single packed array of 16 octets in binary
format. The optional third line specifies the initialization vector (IV) as a
hexadecimal string to be used instead of the segment sequence number (default)
for encryption. Changes to <var>key_info_file</var> will result in segment
encryption with the new key/IV and an entry in the playlist for the new key
URI/IV.
</p>
<p>Key info file format:
</p><div class="example">
<pre class="example"><var>key URI</var>
<var>key file path</var>
<var>IV</var> (optional)
</pre></div>
<p>Example key URIs:
</p><div class="example">
<pre class="example">http://server/file.key
/path/to/file.key
file.key
</pre></div>
<p>Example key file paths:
</p><div class="example">
<pre class="example">file.key
/path/to/file.key
</pre></div>
<p>Example IV:
</p><div class="example">
<pre class="example">0123456789ABCDEF0123456789ABCDEF
</pre></div>
<p>Key info file example:
</p><div class="example">
<pre class="example">http://server/file.key
/path/to/file.key
0123456789ABCDEF0123456789ABCDEF
</pre></div>
<p>Example shell script:
</p><div class="example">
<pre class="example">#!/bin/sh
BASE_URL=${1:-'.'}
openssl rand 16 > file.key
echo $BASE_URL/file.key > file.keyinfo
echo file.key >> file.keyinfo
echo $(openssl rand -hex 16) >> file.keyinfo
ffmpeg -f lavfi -re -i testsrc -c:v h264 -hls_flags delete_segments \
-hls_key_info_file file.keyinfo out.m3u8
</pre></div>
</dd>
<dt><samp>hls_flags single_file</samp></dt>
<dd><p>If this flag is set, the muxer will store all segments in a single MPEG-TS
file, and will use byte ranges in the playlist. HLS playlists generated with
this way will have the version number 4.
For example:
</p><div class="example">
<pre class="example">ffmpeg -i in.nut -hls_flags single_file out.m3u8
</pre></div>
<p>Will produce the playlist, <samp>out.m3u8</samp>, and a single segment file,
<samp>out.ts</samp>.
</p>
</dd>
<dt><samp>hls_flags delete_segments</samp></dt>
<dd><p>Segment files removed from the playlist are deleted after a period of time
equal to the duration of the segment plus the duration of the playlist.
</p></dd>
</dl>
<a name="ico"></a><a name="ico-1"></a>
<h3 class="section">22.7 ico<span class="pull-right"><a class="anchor hidden-xs" href="#ico-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ico-1" aria-hidden="true">TOC</a></span></h3>
<p>ICO file muxer.
</p>
<p>Microsoft’s icon file format (ICO) has some strict limitations that should be noted:
</p>
<ul>
<li> Size cannot exceed 256 pixels in any dimension
</li><li> Only BMP and PNG images can be stored
</li><li> If a BMP image is used, it must be one of the following pixel formats:
<div class="example">
<pre class="example">BMP Bit Depth FFmpeg Pixel Format
1bit pal8
4bit pal8
8bit pal8
16bit rgb555le
24bit bgr24
32bit bgra
</pre></div>
</li><li> If a BMP image is used, it must use the BITMAPINFOHEADER DIB header
</li><li> If a PNG image is used, it must use the rgba pixel format
</li></ul>
<a name="image2"></a><a name="image2-2"></a>
<h3 class="section">22.8 image2<span class="pull-right"><a class="anchor hidden-xs" href="#image2-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-image2-2" aria-hidden="true">TOC</a></span></h3>
<p>Image file muxer.
</p>
<p>The image file muxer writes video frames to image files.
</p>
<p>The output filenames are specified by a pattern, which can be used to
produce sequentially numbered series of files.
The pattern may contain the string "%d" or "%0<var>N</var>d", this string
specifies the position of the characters representing a numbering in
the filenames. If the form "%0<var>N</var>d" is used, the string
representing the number in each filename is 0-padded to <var>N</var>
digits. The literal character ’%’ can be specified in the pattern with
the string "%%".
</p>
<p>If the pattern contains "%d" or "%0<var>N</var>d", the first filename of
the file list specified will contain the number 1, all the following
numbers will be sequential.
</p>
<p>The pattern may contain a suffix which is used to automatically
determine the format of the image files to write.
</p>
<p>For example the pattern "img-%03d.bmp" will specify a sequence of
filenames of the form <samp>img-001.bmp</samp>, <samp>img-002.bmp</samp>, ...,
<samp>img-010.bmp</samp>, etc.
The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
form <samp>img%-1.jpg</samp>, <samp>img%-2.jpg</samp>, ..., <samp>img%-10.jpg</samp>,
etc.
</p>
<a name="Examples-9"></a>
<h4 class="subsection">22.8.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-9" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-9" aria-hidden="true">TOC</a></span></h4>
<p>The following example shows how to use <code>ffmpeg</code> for creating a
sequence of files <samp>img-001.jpeg</samp>, <samp>img-002.jpeg</samp>, ...,
taking one image every second from the input video:
</p><div class="example">
<pre class="example">ffmpeg -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'
</pre></div>
<p>Note that with <code>ffmpeg</code>, if the format is not specified with the
<code>-f</code> option and the output filename specifies an image file
format, the image2 muxer is automatically selected, so the previous
command can be written as:
</p><div class="example">
<pre class="example">ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
</pre></div>
<p>Note also that the pattern must not necessarily contain "%d" or
"%0<var>N</var>d", for example to create a single image file
<samp>img.jpeg</samp> from the input video you can employ the command:
</p><div class="example">
<pre class="example">ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
</pre></div>
<p>The <samp>strftime</samp> option allows you to expand the filename with
date and time information. Check the documentation of
the <code>strftime()</code> function for the syntax.
</p>
<p>For example to generate image files from the <code>strftime()</code>
"%Y-%m-%d_%H-%M-%S" pattern, the following <code>ffmpeg</code> command
can be used:
</p><div class="example">
<pre class="example">ffmpeg -f v4l2 -r 1 -i /dev/video0 -f image2 -strftime 1 "%Y-%m-%d_%H-%M-%S.jpg"
</pre></div>
<a name="Options-33"></a>
<h4 class="subsection">22.8.2 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-33" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-33" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>start_number</samp></dt>
<dd><p>Start the sequence from the specified number. Default value is 0.
</p>
</dd>
<dt><samp>update</samp></dt>
<dd><p>If set to 1, the filename will always be interpreted as just a
filename, not a pattern, and the corresponding file will be continuously
overwritten with new images. Default value is 0.
</p>
</dd>
<dt><samp>strftime</samp></dt>
<dd><p>If set to 1, expand the filename with date and time information from
<code>strftime()</code>. Default value is 0.
</p></dd>
</dl>
<p>The image muxer supports the .Y.U.V image file format. This format is
special in that that each image frame consists of three files, for
each of the YUV420P components. To read or write this image file format,
specify the name of the ’.Y’ file. The muxer will automatically open the
’.U’ and ’.V’ files as required.
</p>
<a name="matroska"></a>
<h3 class="section">22.9 matroska<span class="pull-right"><a class="anchor hidden-xs" href="#matroska" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-matroska" aria-hidden="true">TOC</a></span></h3>
<p>Matroska container muxer.
</p>
<p>This muxer implements the matroska and webm container specs.
</p>
<a name="Metadata"></a>
<h4 class="subsection">22.9.1 Metadata<span class="pull-right"><a class="anchor hidden-xs" href="#Metadata" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Metadata" aria-hidden="true">TOC</a></span></h4>
<p>The recognized metadata settings in this muxer are:
</p>
<dl compact="compact">
<dt><samp>title</samp></dt>
<dd><p>Set title name provided to a single track.
</p>
</dd>
<dt><samp>language</samp></dt>
<dd><p>Specify the language of the track in the Matroska languages form.
</p>
<p>The language can be either the 3 letters bibliographic ISO-639-2 (ISO
639-2/B) form (like "fre" for French), or a language code mixed with a
country code for specialities in languages (like "fre-ca" for Canadian
French).
</p>
</dd>
<dt><samp>stereo_mode</samp></dt>
<dd><p>Set stereo 3D video layout of two views in a single video track.
</p>
<p>The following values are recognized:
</p><dl compact="compact">
<dt>‘<samp>mono</samp>’</dt>
<dd><p>video is not stereo
</p></dd>
<dt>‘<samp>left_right</samp>’</dt>
<dd><p>Both views are arranged side by side, Left-eye view is on the left
</p></dd>
<dt>‘<samp>bottom_top</samp>’</dt>
<dd><p>Both views are arranged in top-bottom orientation, Left-eye view is at bottom
</p></dd>
<dt>‘<samp>top_bottom</samp>’</dt>
<dd><p>Both views are arranged in top-bottom orientation, Left-eye view is on top
</p></dd>
<dt>‘<samp>checkerboard_rl</samp>’</dt>
<dd><p>Each view is arranged in a checkerboard interleaved pattern, Left-eye view being first
</p></dd>
<dt>‘<samp>checkerboard_lr</samp>’</dt>
<dd><p>Each view is arranged in a checkerboard interleaved pattern, Right-eye view being first
</p></dd>
<dt>‘<samp>row_interleaved_rl</samp>’</dt>
<dd><p>Each view is constituted by a row based interleaving, Right-eye view is first row
</p></dd>
<dt>‘<samp>row_interleaved_lr</samp>’</dt>
<dd><p>Each view is constituted by a row based interleaving, Left-eye view is first row
</p></dd>
<dt>‘<samp>col_interleaved_rl</samp>’</dt>
<dd><p>Both views are arranged in a column based interleaving manner, Right-eye view is first column
</p></dd>
<dt>‘<samp>col_interleaved_lr</samp>’</dt>
<dd><p>Both views are arranged in a column based interleaving manner, Left-eye view is first column
</p></dd>
<dt>‘<samp>anaglyph_cyan_red</samp>’</dt>
<dd><p>All frames are in anaglyph format viewable through red-cyan filters
</p></dd>
<dt>‘<samp>right_left</samp>’</dt>
<dd><p>Both views are arranged side by side, Right-eye view is on the left
</p></dd>
<dt>‘<samp>anaglyph_green_magenta</samp>’</dt>
<dd><p>All frames are in anaglyph format viewable through green-magenta filters
</p></dd>
<dt>‘<samp>block_lr</samp>’</dt>
<dd><p>Both eyes laced in one Block, Left-eye view is first
</p></dd>
<dt>‘<samp>block_rl</samp>’</dt>
<dd><p>Both eyes laced in one Block, Right-eye view is first
</p></dd>
</dl>
</dd>
</dl>
<p>For example a 3D WebM clip can be created using the following command line:
</p><div class="example">
<pre class="example">ffmpeg -i sample_left_right_clip.mpg -an -c:v libvpx -metadata stereo_mode=left_right -y stereo_clip.webm
</pre></div>
<a name="Options-34"></a>
<h4 class="subsection">22.9.2 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-34" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-34" aria-hidden="true">TOC</a></span></h4>
<p>This muxer supports the following options:
</p>
<dl compact="compact">
<dt><samp>reserve_index_space</samp></dt>
<dd><p>By default, this muxer writes the index for seeking (called cues in Matroska
terms) at the end of the file, because it cannot know in advance how much space
to leave for the index at the beginning of the file. However for some use cases
– e.g. streaming where seeking is possible but slow – it is useful to put the
index at the beginning of the file.
</p>
<p>If this option is set to a non-zero value, the muxer will reserve a given amount
of space in the file header and then try to write the cues there when the muxing
finishes. If the available space does not suffice, muxing will fail. A safe size
for most use cases should be about 50kB per hour of video.
</p>
<p>Note that cues are only written if the output is seekable and this option will
have no effect if it is not.
</p></dd>
</dl>
<a name="md5"></a><a name="md5-1"></a>
<h3 class="section">22.10 md5<span class="pull-right"><a class="anchor hidden-xs" href="#md5-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-md5-1" aria-hidden="true">TOC</a></span></h3>
<p>MD5 testing format.
</p>
<p>This muxer computes and prints the MD5 hash of all the input audio
and video frames. By default audio frames are converted to signed
16-bit raw audio and video frames to raw video before computing the
hash.
</p>
<p>The output of the muxer consists of a single line of the form:
MD5=<var>MD5</var>, where <var>MD5</var> is a hexadecimal number representing
the computed MD5 hash.
</p>
<p>For example to compute the MD5 hash of the input converted to raw
audio and video, and store it in the file <samp>out.md5</samp>:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f md5 out.md5
</pre></div>
<p>You can print the MD5 to stdout with the command:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f md5 -
</pre></div>
<p>See also the <a href="#framemd5">framemd5</a> muxer.
</p>
<a name="mov_002c-mp4_002c-ismv"></a>
<h3 class="section">22.11 mov, mp4, ismv<span class="pull-right"><a class="anchor hidden-xs" href="#mov_002c-mp4_002c-ismv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mov_002c-mp4_002c-ismv" aria-hidden="true">TOC</a></span></h3>
<p>MOV/MP4/ISMV (Smooth Streaming) muxer.
</p>
<p>The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
file has all the metadata about all packets stored in one location
(written at the end of the file, it can be moved to the start for
better playback by adding <var>faststart</var> to the <var>movflags</var>, or
using the <code>qt-faststart</code> tool). A fragmented
file consists of a number of fragments, where packets and metadata
about these packets are stored together. Writing a fragmented
file has the advantage that the file is decodable even if the
writing is interrupted (while a normal MOV/MP4 is undecodable if
it is not properly finished), and it requires less memory when writing
very long files (since writing normal MOV/MP4 files stores info about
every single packet in memory until the file is closed). The downside
is that it is less compatible with other applications.
</p>
<a name="Options-35"></a>
<h4 class="subsection">22.11.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-35" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-35" aria-hidden="true">TOC</a></span></h4>
<p>Fragmentation is enabled by setting one of the AVOptions that define
how to cut the file into fragments:
</p>
<dl compact="compact">
<dt><samp>-moov_size <var>bytes</var></samp></dt>
<dd><p>Reserves space for the moov atom at the beginning of the file instead of placing the
moov atom at the end. If the space reserved is insufficient, muxing will fail.
</p></dd>
<dt><samp>-movflags frag_keyframe</samp></dt>
<dd><p>Start a new fragment at each video keyframe.
</p></dd>
<dt><samp>-frag_duration <var>duration</var></samp></dt>
<dd><p>Create fragments that are <var>duration</var> microseconds long.
</p></dd>
<dt><samp>-frag_size <var>size</var></samp></dt>
<dd><p>Create fragments that contain up to <var>size</var> bytes of payload data.
</p></dd>
<dt><samp>-movflags frag_custom</samp></dt>
<dd><p>Allow the caller to manually choose when to cut fragments, by
calling <code>av_write_frame(ctx, NULL)</code> to write a fragment with
the packets written so far. (This is only useful with other
applications integrating libavformat, not from <code>ffmpeg</code>.)
</p></dd>
<dt><samp>-min_frag_duration <var>duration</var></samp></dt>
<dd><p>Don’t create fragments that are shorter than <var>duration</var> microseconds long.
</p></dd>
</dl>
<p>If more than one condition is specified, fragments are cut when
one of the specified conditions is fulfilled. The exception to this is
<code>-min_frag_duration</code>, which has to be fulfilled for any of the other
conditions to apply.
</p>
<p>Additionally, the way the output file is written can be adjusted
through a few other options:
</p>
<dl compact="compact">
<dt><samp>-movflags empty_moov</samp></dt>
<dd><p>Write an initial moov atom directly at the start of the file, without
describing any samples in it. Generally, an mdat/moov pair is written
at the start of the file, as a normal MOV/MP4 file, containing only
a short portion of the file. With this option set, there is no initial
mdat atom, and the moov atom only describes the tracks but has
a zero duration.
</p>
<p>This option is implicitly set when writing ismv (Smooth Streaming) files.
</p></dd>
<dt><samp>-movflags separate_moof</samp></dt>
<dd><p>Write a separate moof (movie fragment) atom for each track. Normally,
packets for all tracks are written in a moof atom (which is slightly
more efficient), but with this option set, the muxer writes one moof/mdat
pair for each track, making it easier to separate tracks.
</p>
<p>This option is implicitly set when writing ismv (Smooth Streaming) files.
</p></dd>
<dt><samp>-movflags faststart</samp></dt>
<dd><p>Run a second pass moving the index (moov atom) to the beginning of the file.
This operation can take a while, and will not work in various situations such
as fragmented output, thus it is not enabled by default.
</p></dd>
<dt><samp>-movflags rtphint</samp></dt>
<dd><p>Add RTP hinting tracks to the output file.
</p></dd>
<dt><samp>-movflags disable_chpl</samp></dt>
<dd><p>Disable Nero chapter markers (chpl atom). Normally, both Nero chapters
and a QuickTime chapter track are written to the file. With this option
set, only the QuickTime chapter track will be written. Nero chapters can
cause failures when the file is reprocessed with certain tagging programs, like
mp3Tag 2.61a and iTunes 11.3, most likely other versions are affected as well.
</p></dd>
<dt><samp>-movflags omit_tfhd_offset</samp></dt>
<dd><p>Do not write any absolute base_data_offset in tfhd atoms. This avoids
tying fragments to absolute byte positions in the file/streams.
</p></dd>
<dt><samp>-movflags default_base_moof</samp></dt>
<dd><p>Similarly to the omit_tfhd_offset, this flag avoids writing the
absolute base_data_offset field in tfhd atoms, but does so by using
the new default-base-is-moof flag instead. This flag is new from
14496-12:2012. This may make the fragments easier to parse in certain
circumstances (avoiding basing track fragment location calculations
on the implicit end of the previous track fragment).
</p></dd>
</dl>
<a name="Example"></a>
<h4 class="subsection">22.11.2 Example<span class="pull-right"><a class="anchor hidden-xs" href="#Example" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Example" aria-hidden="true">TOC</a></span></h4>
<p>Smooth Streaming content can be pushed in real time to a publishing
point on IIS with this muxer. Example:
</p><div class="example">
<pre class="example">ffmpeg -re <var><normal input/transcoding options></var> -movflags isml+frag_keyframe -f ismv http://server/publishingpoint.isml/Streams(Encoder1)
</pre></div>
<a name="Audible-AAX"></a>
<h4 class="subsection">22.11.3 Audible AAX<span class="pull-right"><a class="anchor hidden-xs" href="#Audible-AAX" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audible-AAX" aria-hidden="true">TOC</a></span></h4>
<p>Audible AAX files are encrypted M4B files, and they can be decrypted by specifying a 4 byte activation secret.
</p><div class="example">
<pre class="example">ffmpeg -activation_bytes 1CEB00DA -i test.aax -vn -c:a copy output.mp4
</pre></div>
<a name="mp3"></a>
<h3 class="section">22.12 mp3<span class="pull-right"><a class="anchor hidden-xs" href="#mp3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mp3" aria-hidden="true">TOC</a></span></h3>
<p>The MP3 muxer writes a raw MP3 stream with the following optional features:
</p><ul>
<li> An ID3v2 metadata header at the beginning (enabled by default). Versions 2.3 and
2.4 are supported, the <code>id3v2_version</code> private option controls which one is
used (3 or 4). Setting <code>id3v2_version</code> to 0 disables the ID3v2 header
completely.
<p>The muxer supports writing attached pictures (APIC frames) to the ID3v2 header.
The pictures are supplied to the muxer in form of a video stream with a single
packet. There can be any number of those streams, each will correspond to a
single APIC frame. The stream metadata tags <var>title</var> and <var>comment</var> map
to APIC <var>description</var> and <var>picture type</var> respectively. See
<a href="http://id3.org/id3v2.4.0-frames">http://id3.org/id3v2.4.0-frames</a> for allowed picture types.
</p>
<p>Note that the APIC frames must be written at the beginning, so the muxer will
buffer the audio frames until it gets all the pictures. It is therefore advised
to provide the pictures as soon as possible to avoid excessive buffering.
</p>
</li><li> A Xing/LAME frame right after the ID3v2 header (if present). It is enabled by
default, but will be written only if the output is seekable. The
<code>write_xing</code> private option can be used to disable it. The frame contains
various information that may be useful to the decoder, like the audio duration
or encoder delay.
</li><li> A legacy ID3v1 tag at the end of the file (disabled by default). It may be
enabled with the <code>write_id3v1</code> private option, but as its capabilities are
very limited, its usage is not recommended.
</li></ul>
<p>Examples:
</p>
<p>Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -id3v2_version 3 -write_id3v1 1 out.mp3
</pre></div>
<p>To attach a picture to an mp3 file select both the audio and the picture stream
with <code>map</code>:
</p><div class="example">
<pre class="example">ffmpeg -i input.mp3 -i cover.png -c copy -map 0 -map 1
-metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" out.mp3
</pre></div>
<p>Write a "clean" MP3 without any extra features:
</p><div class="example">
<pre class="example">ffmpeg -i input.wav -write_xing 0 -id3v2_version 0 out.mp3
</pre></div>
<a name="mpegts-1"></a>
<h3 class="section">22.13 mpegts<span class="pull-right"><a class="anchor hidden-xs" href="#mpegts-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mpegts-1" aria-hidden="true">TOC</a></span></h3>
<p>MPEG transport stream muxer.
</p>
<p>This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
</p>
<p>The recognized metadata settings in mpegts muxer are <code>service_provider</code>
and <code>service_name</code>. If they are not set the default for
<code>service_provider</code> is "FFmpeg" and the default for
<code>service_name</code> is "Service01".
</p>
<a name="Options-36"></a>
<h4 class="subsection">22.13.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-36" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-36" aria-hidden="true">TOC</a></span></h4>
<p>The muxer options are:
</p>
<dl compact="compact">
<dt><samp>-mpegts_original_network_id <var>number</var></samp></dt>
<dd><p>Set the original_network_id (default 0x0001). This is unique identifier
of a network in DVB. Its main use is in the unique identification of a
service through the path Original_Network_ID, Transport_Stream_ID.
</p></dd>
<dt><samp>-mpegts_transport_stream_id <var>number</var></samp></dt>
<dd><p>Set the transport_stream_id (default 0x0001). This identifies a
transponder in DVB.
</p></dd>
<dt><samp>-mpegts_service_id <var>number</var></samp></dt>
<dd><p>Set the service_id (default 0x0001) also known as program in DVB.
</p></dd>
<dt><samp>-mpegts_service_type <var>number</var></samp></dt>
<dd><p>Set the program service_type (default <var>digital_tv</var>), see below
a list of pre defined values.
</p></dd>
<dt><samp>-mpegts_pmt_start_pid <var>number</var></samp></dt>
<dd><p>Set the first PID for PMT (default 0x1000, max 0x1f00).
</p></dd>
<dt><samp>-mpegts_start_pid <var>number</var></samp></dt>
<dd><p>Set the first PID for data packets (default 0x0100, max 0x0f00).
</p></dd>
<dt><samp>-mpegts_m2ts_mode <var>number</var></samp></dt>
<dd><p>Enable m2ts mode if set to 1. Default value is -1 which disables m2ts mode.
</p></dd>
<dt><samp>-muxrate <var>number</var></samp></dt>
<dd><p>Set a constant muxrate (default VBR).
</p></dd>
<dt><samp>-pcr_period <var>numer</var></samp></dt>
<dd><p>Override the default PCR retransmission time (default 20ms), ignored
if variable muxrate is selected.
</p></dd>
<dt><samp>pat_period <var>number</var></samp></dt>
<dd><p>Maximal time in seconds between PAT/PMT tables.
</p></dd>
<dt><samp>sdt_period <var>number</var></samp></dt>
<dd><p>Maximal time in seconds between SDT tables.
</p></dd>
<dt><samp>-pes_payload_size <var>number</var></samp></dt>
<dd><p>Set minimum PES packet payload in bytes.
</p></dd>
<dt><samp>-mpegts_flags <var>flags</var></samp></dt>
<dd><p>Set flags (see below).
</p></dd>
<dt><samp>-mpegts_copyts <var>number</var></samp></dt>
<dd><p>Preserve original timestamps, if value is set to 1. Default value is -1, which
results in shifting timestamps so that they start from 0.
</p></dd>
<dt><samp>-tables_version <var>number</var></samp></dt>
<dd><p>Set PAT, PMT and SDT version (default 0, valid values are from 0 to 31, inclusively).
This option allows updating stream structure so that standard consumer may
detect the change. To do so, reopen output AVFormatContext (in case of API
usage) or restart ffmpeg instance, cyclically changing tables_version value:
</p><div class="example">
<pre class="example">ffmpeg -i source1.ts -codec copy -f mpegts -tables_version 0 udp://1.1.1.1:1111
ffmpeg -i source2.ts -codec copy -f mpegts -tables_version 1 udp://1.1.1.1:1111
...
ffmpeg -i source3.ts -codec copy -f mpegts -tables_version 31 udp://1.1.1.1:1111
ffmpeg -i source1.ts -codec copy -f mpegts -tables_version 0 udp://1.1.1.1:1111
ffmpeg -i source2.ts -codec copy -f mpegts -tables_version 1 udp://1.1.1.1:1111
...
</pre></div>
</dd>
</dl>
<p>Option mpegts_service_type accepts the following values:
</p>
<dl compact="compact">
<dt><samp>hex_value</samp></dt>
<dd><p>Any hexdecimal value between 0x01 to 0xff as defined in ETSI 300 468.
</p></dd>
<dt><samp>digital_tv</samp></dt>
<dd><p>Digital TV service.
</p></dd>
<dt><samp>digital_radio</samp></dt>
<dd><p>Digital Radio service.
</p></dd>
<dt><samp>teletext</samp></dt>
<dd><p>Teletext service.
</p></dd>
<dt><samp>advanced_codec_digital_radio</samp></dt>
<dd><p>Advanced Codec Digital Radio service.
</p></dd>
<dt><samp>mpeg2_digital_hdtv</samp></dt>
<dd><p>MPEG2 Digital HDTV service.
</p></dd>
<dt><samp>advanced_codec_digital_sdtv</samp></dt>
<dd><p>Advanced Codec Digital SDTV service.
</p></dd>
<dt><samp>advanced_codec_digital_hdtv</samp></dt>
<dd><p>Advanced Codec Digital HDTV service.
</p></dd>
</dl>
<p>Option mpegts_flags may take a set of such flags:
</p>
<dl compact="compact">
<dt><samp>resend_headers</samp></dt>
<dd><p>Reemit PAT/PMT before writing the next packet.
</p></dd>
<dt><samp>latm</samp></dt>
<dd><p>Use LATM packetization for AAC.
</p></dd>
<dt><samp>pat_pmt_at_frames</samp></dt>
<dd><p>Reemit PAT and PMT at each video frame.
</p></dd>
</dl>
<a name="Example-1"></a>
<h4 class="subsection">22.13.2 Example<span class="pull-right"><a class="anchor hidden-xs" href="#Example-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Example-1" aria-hidden="true">TOC</a></span></h4>
<div class="example">
<pre class="example">ffmpeg -i file.mpg -c copy \
-mpegts_original_network_id 0x1122 \
-mpegts_transport_stream_id 0x3344 \
-mpegts_service_id 0x5566 \
-mpegts_pmt_start_pid 0x1500 \
-mpegts_start_pid 0x150 \
-metadata service_provider="Some provider" \
-metadata service_name="Some Channel" \
-y out.ts
</pre></div>
<a name="mxf_002c-mxf_005fd10"></a>
<h3 class="section">22.14 mxf, mxf_d10<span class="pull-right"><a class="anchor hidden-xs" href="#mxf_002c-mxf_005fd10" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mxf_002c-mxf_005fd10" aria-hidden="true">TOC</a></span></h3>
<p>MXF muxer.
</p>
<a name="Options-37"></a>
<h4 class="subsection">22.14.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-37" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-37" aria-hidden="true">TOC</a></span></h4>
<p>The muxer options are:
</p>
<dl compact="compact">
<dt><samp>store_user_comments <var>bool</var></samp></dt>
<dd><p>Set if user comments should be stored if available or never.
IRT D-10 does not allow user comments. The default is thus to write them for
mxf but not for mxf_d10
</p></dd>
</dl>
<a name="null"></a>
<h3 class="section">22.15 null<span class="pull-right"><a class="anchor hidden-xs" href="#null" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-null" aria-hidden="true">TOC</a></span></h3>
<p>Null muxer.
</p>
<p>This muxer does not generate any output file, it is mainly useful for
testing or benchmarking purposes.
</p>
<p>For example to benchmark decoding with <code>ffmpeg</code> you can use the
command:
</p><div class="example">
<pre class="example">ffmpeg -benchmark -i INPUT -f null out.null
</pre></div>
<p>Note that the above command does not read or write the <samp>out.null</samp>
file, but specifying the output file is required by the <code>ffmpeg</code>
syntax.
</p>
<p>Alternatively you can write the command as:
</p><div class="example">
<pre class="example">ffmpeg -benchmark -i INPUT -f null -
</pre></div>
<a name="nut"></a>
<h3 class="section">22.16 nut<span class="pull-right"><a class="anchor hidden-xs" href="#nut" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-nut" aria-hidden="true">TOC</a></span></h3>
<dl compact="compact">
<dt><samp>-syncpoints <var>flags</var></samp></dt>
<dd><p>Change the syncpoint usage in nut:
</p><dl compact="compact">
<dt><samp><var>default</var> use the normal low-overhead seeking aids.</samp></dt>
<dt><samp><var>none</var> do not use the syncpoints at all, reducing the overhead but making the stream non-seekable;</samp></dt>
<dd><p>Use of this option is not recommended, as the resulting files are very damage
sensitive and seeking is not possible. Also in general the overhead from
syncpoints is negligible. Note, -<code>write_index</code> 0 can be used to disable
all growing data tables, allowing to mux endless streams with limited memory
and without these disadvantages.
</p></dd>
<dt><samp><var>timestamped</var> extend the syncpoint with a wallclock field.</samp></dt>
</dl>
<p>The <var>none</var> and <var>timestamped</var> flags are experimental.
</p></dd>
<dt><samp>-write_index <var>bool</var></samp></dt>
<dd><p>Write index at the end, the default is to write an index.
</p></dd>
</dl>
<div class="example">
<pre class="example">ffmpeg -i INPUT -f_strict experimental -syncpoints none - | processor
</pre></div>
<a name="ogg"></a>
<h3 class="section">22.17 ogg<span class="pull-right"><a class="anchor hidden-xs" href="#ogg" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ogg" aria-hidden="true">TOC</a></span></h3>
<p>Ogg container muxer.
</p>
<dl compact="compact">
<dt><samp>-page_duration <var>duration</var></samp></dt>
<dd><p>Preferred page duration, in microseconds. The muxer will attempt to create
pages that are approximately <var>duration</var> microseconds long. This allows the
user to compromise between seek granularity and container overhead. The default
is 1 second. A value of 0 will fill all segments, making pages as large as
possible. A value of 1 will effectively use 1 packet-per-page in most
situations, giving a small seek granularity at the cost of additional container
overhead.
</p></dd>
<dt><samp>-serial_offset <var>value</var></samp></dt>
<dd><p>Serial value from which to set the streams serial number.
Setting it to different and sufficiently large values ensures that the produced
ogg files can be safely chained.
</p>
</dd>
</dl>
<a name="segment"></a><a name="segment_002c-stream_005fsegment_002c-ssegment"></a>
<h3 class="section">22.18 segment, stream_segment, ssegment<span class="pull-right"><a class="anchor hidden-xs" href="#segment_002c-stream_005fsegment_002c-ssegment" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-segment_002c-stream_005fsegment_002c-ssegment" aria-hidden="true">TOC</a></span></h3>
<p>Basic stream segmenter.
</p>
<p>This muxer outputs streams to a number of separate files of nearly
fixed duration. Output filename pattern can be set in a fashion
similar to <a href="#image2">image2</a>, or by using a <code>strftime</code> template if
the <samp>strftime</samp> option is enabled.
</p>
<p><code>stream_segment</code> is a variant of the muxer used to write to
streaming output formats, i.e. which do not require global headers,
and is recommended for outputting e.g. to MPEG transport stream segments.
<code>ssegment</code> is a shorter alias for <code>stream_segment</code>.
</p>
<p>Every segment starts with a keyframe of the selected reference stream,
which is set through the <samp>reference_stream</samp> option.
</p>
<p>Note that if you want accurate splitting for a video file, you need to
make the input key frames correspond to the exact splitting times
expected by the segmenter, or the segment muxer will start the new
segment with the key frame found next after the specified start
time.
</p>
<p>The segment muxer works best with a single constant frame rate video.
</p>
<p>Optionally it can generate a list of the created segments, by setting
the option <var>segment_list</var>. The list type is specified by the
<var>segment_list_type</var> option. The entry filenames in the segment
list are set by default to the basename of the corresponding segment
files.
</p>
<p>See also the <a href="#hls">hls</a> muxer, which provides a more specific
implementation for HLS segmentation.
</p>
<a name="Options-38"></a>
<h4 class="subsection">22.18.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-38" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-38" aria-hidden="true">TOC</a></span></h4>
<p>The segment muxer supports the following options:
</p>
<dl compact="compact">
<dt><samp>reference_stream <var>specifier</var></samp></dt>
<dd><p>Set the reference stream, as specified by the string <var>specifier</var>.
If <var>specifier</var> is set to <code>auto</code>, the reference is chosen
automatically. Otherwise it must be a stream specifier (see the “Stream
specifiers” chapter in the ffmpeg manual) which specifies the
reference stream. The default value is <code>auto</code>.
</p>
</dd>
<dt><samp>segment_format <var>format</var></samp></dt>
<dd><p>Override the inner container format, by default it is guessed by the filename
extension.
</p>
</dd>
<dt><samp>segment_format_options <var>options_list</var></samp></dt>
<dd><p>Set output format options using a :-separated list of key=value
parameters. Values containing the <code>:</code> special character must be
escaped.
</p>
</dd>
<dt><samp>segment_list <var>name</var></samp></dt>
<dd><p>Generate also a listfile named <var>name</var>. If not specified no
listfile is generated.
</p>
</dd>
<dt><samp>segment_list_flags <var>flags</var></samp></dt>
<dd><p>Set flags affecting the segment list generation.
</p>
<p>It currently supports the following flags:
</p><dl compact="compact">
<dt>‘<samp>cache</samp>’</dt>
<dd><p>Allow caching (only affects M3U8 list files).
</p>
</dd>
<dt>‘<samp>live</samp>’</dt>
<dd><p>Allow live-friendly file generation.
</p></dd>
</dl>
</dd>
<dt><samp>segment_list_size <var>size</var></samp></dt>
<dd><p>Update the list file so that it contains at most <var>size</var>
segments. If 0 the list file will contain all the segments. Default
value is 0.
</p>
</dd>
<dt><samp>segment_list_entry_prefix <var>prefix</var></samp></dt>
<dd><p>Prepend <var>prefix</var> to each entry. Useful to generate absolute paths.
By default no prefix is applied.
</p>
</dd>
<dt><samp>segment_list_type <var>type</var></samp></dt>
<dd><p>Select the listing format.
</p>
<p>The following values are recognized:
</p><dl compact="compact">
<dt>‘<samp>flat</samp>’</dt>
<dd><p>Generate a flat list for the created segments, one segment per line.
</p>
</dd>
<dt>‘<samp>csv, ext</samp>’</dt>
<dd><p>Generate a list for the created segments, one segment per line,
each line matching the format (comma-separated values):
</p><div class="example">
<pre class="example"><var>segment_filename</var>,<var>segment_start_time</var>,<var>segment_end_time</var>
</pre></div>
<p><var>segment_filename</var> is the name of the output file generated by the
muxer according to the provided pattern. CSV escaping (according to
RFC4180) is applied if required.
</p>
<p><var>segment_start_time</var> and <var>segment_end_time</var> specify
the segment start and end time expressed in seconds.
</p>
<p>A list file with the suffix <code>".csv"</code> or <code>".ext"</code> will
auto-select this format.
</p>
<p>‘<samp>ext</samp>’ is deprecated in favor or ‘<samp>csv</samp>’.
</p>
</dd>
<dt>‘<samp>ffconcat</samp>’</dt>
<dd><p>Generate an ffconcat file for the created segments. The resulting file
can be read using the FFmpeg <a href="#concat">concat</a> demuxer.
</p>
<p>A list file with the suffix <code>".ffcat"</code> or <code>".ffconcat"</code> will
auto-select this format.
</p>
</dd>
<dt>‘<samp>m3u8</samp>’</dt>
<dd><p>Generate an extended M3U8 file, version 3, compliant with
<a href="http://tools.ietf.org/id/draft-pantos-http-live-streaming">http://tools.ietf.org/id/draft-pantos-http-live-streaming</a>.
</p>
<p>A list file with the suffix <code>".m3u8"</code> will auto-select this format.
</p></dd>
</dl>
<p>If not specified the type is guessed from the list file name suffix.
</p>
</dd>
<dt><samp>segment_time <var>time</var></samp></dt>
<dd><p>Set segment duration to <var>time</var>, the value must be a duration
specification. Default value is "2". See also the
<samp>segment_times</samp> option.
</p>
<p>Note that splitting may not be accurate, unless you force the
reference stream key-frames at the given time. See the introductory
notice and the examples below.
</p>
</dd>
<dt><samp>segment_atclocktime <var>1|0</var></samp></dt>
<dd><p>If set to "1" split at regular clock time intervals starting from 00:00
o’clock. The <var>time</var> value specified in <samp>segment_time</samp> is
used for setting the length of the splitting interval.
</p>
<p>For example with <samp>segment_time</samp> set to "900" this makes it possible
to create files at 12:00 o’clock, 12:15, 12:30, etc.
</p>
<p>Default value is "0".
</p>
</dd>
<dt><samp>segment_time_delta <var>delta</var></samp></dt>
<dd><p>Specify the accuracy time when selecting the start time for a
segment, expressed as a duration specification. Default value is "0".
</p>
<p>When delta is specified a key-frame will start a new segment if its
PTS satisfies the relation:
</p><div class="example">
<pre class="example">PTS >= start_time - time_delta
</pre></div>
<p>This option is useful when splitting video content, which is always
split at GOP boundaries, in case a key frame is found just before the
specified split time.
</p>
<p>In particular may be used in combination with the <samp>ffmpeg</samp> option
<var>force_key_frames</var>. The key frame times specified by
<var>force_key_frames</var> may not be set accurately because of rounding
issues, with the consequence that a key frame time may result set just
before the specified time. For constant frame rate videos a value of
1/(2*<var>frame_rate</var>) should address the worst case mismatch between
the specified time and the time set by <var>force_key_frames</var>.
</p>
</dd>
<dt><samp>segment_times <var>times</var></samp></dt>
<dd><p>Specify a list of split points. <var>times</var> contains a list of comma
separated duration specifications, in increasing order. See also
the <samp>segment_time</samp> option.
</p>
</dd>
<dt><samp>segment_frames <var>frames</var></samp></dt>
<dd><p>Specify a list of split video frame numbers. <var>frames</var> contains a
list of comma separated integer numbers, in increasing order.
</p>
<p>This option specifies to start a new segment whenever a reference
stream key frame is found and the sequential number (starting from 0)
of the frame is greater or equal to the next value in the list.
</p>
</dd>
<dt><samp>segment_wrap <var>limit</var></samp></dt>
<dd><p>Wrap around segment index once it reaches <var>limit</var>.
</p>
</dd>
<dt><samp>segment_start_number <var>number</var></samp></dt>
<dd><p>Set the sequence number of the first segment. Defaults to <code>0</code>.
</p>
</dd>
<dt><samp>strftime <var>1|0</var></samp></dt>
<dd><p>Use the <code>strftime</code> function to define the name of the new
segments to write. If this is selected, the output segment name must
contain a <code>strftime</code> function template. Default value is
<code>0</code>.
</p>
</dd>
<dt><samp>break_non_keyframes <var>1|0</var></samp></dt>
<dd><p>If enabled, allow segments to start on frames other than keyframes. This
improves behavior on some players when the time between keyframes is
inconsistent, but may make things worse on others, and can cause some oddities
during seeking. Defaults to <code>0</code>.
</p>
</dd>
<dt><samp>reset_timestamps <var>1|0</var></samp></dt>
<dd><p>Reset timestamps at the begin of each segment, so that each segment
will start with near-zero timestamps. It is meant to ease the playback
of the generated segments. May not work with some combinations of
muxers/codecs. It is set to <code>0</code> by default.
</p>
</dd>
<dt><samp>initial_offset <var>offset</var></samp></dt>
<dd><p>Specify timestamp offset to apply to the output packet timestamps. The
argument must be a time duration specification, and defaults to 0.
</p></dd>
</dl>
<a name="Examples-10"></a>
<h4 class="subsection">22.18.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-10" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-10" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Remux the content of file <samp>in.mkv</samp> to a list of segments
<samp>out-000.nut</samp>, <samp>out-001.nut</samp>, etc., and write the list of
generated segments to <samp>out.list</samp>:
<div class="example">
<pre class="example">ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.list out%03d.nut
</pre></div>
</li><li> Segment input and set output format options for the output segments:
<div class="example">
<pre class="example">ffmpeg -i in.mkv -f segment -segment_time 10 -segment_format_options movflags=+faststart out%03d.mp4
</pre></div>
</li><li> Segment the input file according to the split points specified by the
<var>segment_times</var> option:
<div class="example">
<pre class="example">ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 out%03d.nut
</pre></div>
</li><li> Use the <code>ffmpeg</code> <samp>force_key_frames</samp>
option to force key frames in the input at the specified location, together
with the segment option <samp>segment_time_delta</samp> to account for
possible roundings operated when setting key frame times.
<div class="example">
<pre class="example">ffmpeg -i in.mkv -force_key_frames 1,2,3,5,8,13,21 -codec:v mpeg4 -codec:a pcm_s16le -map 0 \
-f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 -segment_time_delta 0.05 out%03d.nut
</pre></div>
<p>In order to force key frames on the input file, transcoding is
required.
</p>
</li><li> Segment the input file by splitting the input file according to the
frame numbers sequence specified with the <samp>segment_frames</samp> option:
<div class="example">
<pre class="example">ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_frames 100,200,300,500,800 out%03d.nut
</pre></div>
</li><li> Convert the <samp>in.mkv</samp> to TS segments using the <code>libx264</code>
and <code>libfaac</code> encoders:
<div class="example">
<pre class="example">ffmpeg -i in.mkv -map 0 -codec:v libx264 -codec:a libfaac -f ssegment -segment_list out.list out%03d.ts
</pre></div>
</li><li> Segment the input file, and create an M3U8 live playlist (can be used
as live HLS source):
<div class="example">
<pre class="example">ffmpeg -re -i in.mkv -codec copy -map 0 -f segment -segment_list playlist.m3u8 \
-segment_list_flags +live -segment_time 10 out%03d.mkv
</pre></div>
</li></ul>
<a name="smoothstreaming"></a>
<h3 class="section">22.19 smoothstreaming<span class="pull-right"><a class="anchor hidden-xs" href="#smoothstreaming" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-smoothstreaming" aria-hidden="true">TOC</a></span></h3>
<p>Smooth Streaming muxer generates a set of files (Manifest, chunks) suitable for serving with conventional web server.
</p>
<dl compact="compact">
<dt><samp>window_size</samp></dt>
<dd><p>Specify the number of fragments kept in the manifest. Default 0 (keep all).
</p>
</dd>
<dt><samp>extra_window_size</samp></dt>
<dd><p>Specify the number of fragments kept outside of the manifest before removing from disk. Default 5.
</p>
</dd>
<dt><samp>lookahead_count</samp></dt>
<dd><p>Specify the number of lookahead fragments. Default 2.
</p>
</dd>
<dt><samp>min_frag_duration</samp></dt>
<dd><p>Specify the minimum fragment duration (in microseconds). Default 5000000.
</p>
</dd>
<dt><samp>remove_at_exit</samp></dt>
<dd><p>Specify whether to remove all fragments when finished. Default 0 (do not remove).
</p>
</dd>
</dl>
<a name="tee"></a>
<h3 class="section">22.20 tee<span class="pull-right"><a class="anchor hidden-xs" href="#tee" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tee" aria-hidden="true">TOC</a></span></h3>
<p>The tee muxer can be used to write the same data to several files or any
other kind of muxer. It can be used, for example, to both stream a video to
the network and save it to disk at the same time.
</p>
<p>It is different from specifying several outputs to the <code>ffmpeg</code>
command-line tool because the audio and video data will be encoded only once
with the tee muxer; encoding can be a very expensive process. It is not
useful when using the libavformat API directly because it is then possible
to feed the same packets to several muxers directly.
</p>
<p>The slave outputs are specified in the file name given to the muxer,
separated by ’|’. If any of the slave name contains the ’|’ separator,
leading or trailing spaces or any special character, it must be
escaped (see <a href="ffmpeg-utils.html#quoting_005fand_005fescaping">(ffmpeg-utils)the "Quoting and escaping"
section in the ffmpeg-utils(1) manual</a>).
</p>
<p>Muxer options can be specified for each slave by prepending them as a list of
<var>key</var>=<var>value</var> pairs separated by ’:’, between square brackets. If
the options values contain a special character or the ’:’ separator, they
must be escaped; note that this is a second level escaping.
</p>
<p>The following special options are also recognized:
</p><dl compact="compact">
<dt><samp>f</samp></dt>
<dd><p>Specify the format name. Useful if it cannot be guessed from the
output name suffix.
</p>
</dd>
<dt><samp>bsfs[/<var>spec</var>]</samp></dt>
<dd><p>Specify a list of bitstream filters to apply to the specified
output.
</p>
<p>It is possible to specify to which streams a given bitstream filter
applies, by appending a stream specifier to the option separated by
<code>/</code>. <var>spec</var> must be a stream specifier (see <a href="#Format-stream-specifiers">Format stream specifiers</a>). If the stream specifier is not specified, the
bitstream filters will be applied to all streams in the output.
</p>
<p>Several bitstream filters can be specified, separated by ",".
</p>
</dd>
<dt><samp>select</samp></dt>
<dd><p>Select the streams that should be mapped to the slave output,
specified by a stream specifier. If not specified, this defaults to
all the input streams.
</p></dd>
</dl>
<a name="Examples-11"></a>
<h4 class="subsection">22.20.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-11" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-11" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Encode something and both archive it in a WebM file and stream it
as MPEG-TS over UDP (the streams need to be explicitly mapped):
<div class="example">
<pre class="example">ffmpeg -i ... -c:v libx264 -c:a mp2 -f tee -map 0:v -map 0:a
"archive-20121107.mkv|[f=mpegts]udp://10.0.1.255:1234/"
</pre></div>
</li><li> Use <code>ffmpeg</code> to encode the input, and send the output
to three different destinations. The <code>dump_extra</code> bitstream
filter is used to add extradata information to all the output video
keyframes packets, as requested by the MPEG-TS format. The select
option is applied to <samp>out.aac</samp> in order to make it contain only
audio packets.
<div class="example">
<pre class="example">ffmpeg -i ... -map 0 -flags +global_header -c:v libx264 -c:a aac -strict experimental
-f tee "[bsfs/v=dump_extra]out.ts|[movflags=+faststart]out.mp4|[select=a]out.aac"
</pre></div>
</li><li> As below, but select only stream <code>a:1</code> for the audio output. Note
that a second level escaping must be performed, as ":" is a special
character used to separate options.
<div class="example">
<pre class="example">ffmpeg -i ... -map 0 -flags +global_header -c:v libx264 -c:a aac -strict experimental
-f tee "[bsfs/v=dump_extra]out.ts|[movflags=+faststart]out.mp4|[select=\'a:1\']out.aac"
</pre></div>
</li></ul>
<p>Note: some codecs may need different options depending on the output format;
the auto-detection of this can not work with the tee muxer. The main example
is the <samp>global_header</samp> flag.
</p>
<a name="webm_005fdash_005fmanifest"></a>
<h3 class="section">22.21 webm_dash_manifest<span class="pull-right"><a class="anchor hidden-xs" href="#webm_005fdash_005fmanifest" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-webm_005fdash_005fmanifest" aria-hidden="true">TOC</a></span></h3>
<p>WebM DASH Manifest muxer.
</p>
<p>This muxer implements the WebM DASH Manifest specification to generate the DASH
manifest XML. It also supports manifest generation for DASH live streams.
</p>
<p>For more information see:
</p>
<ul>
<li> WebM DASH Specification: <a href="https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification">https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification</a>
</li><li> ISO DASH Specification: <a href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip</a>
</li></ul>
<a name="Options-39"></a>
<h4 class="subsection">22.21.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-39" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-39" aria-hidden="true">TOC</a></span></h4>
<p>This muxer supports the following options:
</p>
<dl compact="compact">
<dt><samp>adaptation_sets</samp></dt>
<dd><p>This option has the following syntax: "id=x,streams=a,b,c id=y,streams=d,e" where x and y are the
unique identifiers of the adaptation sets and a,b,c,d and e are the indices of the corresponding
audio and video streams. Any number of adaptation sets can be added using this option.
</p>
</dd>
<dt><samp>live</samp></dt>
<dd><p>Set this to 1 to create a live stream DASH Manifest. Default: 0.
</p>
</dd>
<dt><samp>chunk_start_index</samp></dt>
<dd><p>Start index of the first chunk. This will go in the ‘<samp>startNumber</samp>’ attribute
of the ‘<samp>SegmentTemplate</samp>’ element in the manifest. Default: 0.
</p>
</dd>
<dt><samp>chunk_duration_ms</samp></dt>
<dd><p>Duration of each chunk in milliseconds. This will go in the ‘<samp>duration</samp>’
attribute of the ‘<samp>SegmentTemplate</samp>’ element in the manifest. Default: 1000.
</p>
</dd>
<dt><samp>utc_timing_url</samp></dt>
<dd><p>URL of the page that will return the UTC timestamp in ISO format. This will go
in the ‘<samp>value</samp>’ attribute of the ‘<samp>UTCTiming</samp>’ element in the manifest.
Default: None.
</p>
</dd>
<dt><samp>time_shift_buffer_depth</samp></dt>
<dd><p>Smallest time (in seconds) shifting buffer for which any Representation is
guaranteed to be available. This will go in the ‘<samp>timeShiftBufferDepth</samp>’
attribute of the ‘<samp>MPD</samp>’ element. Default: 60.
</p>
</dd>
<dt><samp>minimum_update_period</samp></dt>
<dd><p>Minimum update period (in seconds) of the manifest. This will go in the
‘<samp>minimumUpdatePeriod</samp>’ attribute of the ‘<samp>MPD</samp>’ element. Default: 0.
</p>
</dd>
</dl>
<a name="Example-2"></a>
<h4 class="subsection">22.21.2 Example<span class="pull-right"><a class="anchor hidden-xs" href="#Example-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Example-2" aria-hidden="true">TOC</a></span></h4>
<div class="example">
<pre class="example">ffmpeg -f webm_dash_manifest -i video1.webm \
-f webm_dash_manifest -i video2.webm \
-f webm_dash_manifest -i audio1.webm \
-f webm_dash_manifest -i audio2.webm \
-map 0 -map 1 -map 2 -map 3 \
-c copy \
-f webm_dash_manifest \
-adaptation_sets "id=0,streams=0,1 id=1,streams=2,3" \
manifest.xml
</pre></div>
<a name="webm_005fchunk"></a>
<h3 class="section">22.22 webm_chunk<span class="pull-right"><a class="anchor hidden-xs" href="#webm_005fchunk" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-webm_005fchunk" aria-hidden="true">TOC</a></span></h3>
<p>WebM Live Chunk Muxer.
</p>
<p>This muxer writes out WebM headers and chunks as separate files which can be
consumed by clients that support WebM Live streams via DASH.
</p>
<a name="Options-40"></a>
<h4 class="subsection">22.22.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-40" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-40" aria-hidden="true">TOC</a></span></h4>
<p>This muxer supports the following options:
</p>
<dl compact="compact">
<dt><samp>chunk_start_index</samp></dt>
<dd><p>Index of the first chunk (defaults to 0).
</p>
</dd>
<dt><samp>header</samp></dt>
<dd><p>Filename of the header where the initialization data will be written.
</p>
</dd>
<dt><samp>audio_chunk_duration</samp></dt>
<dd><p>Duration of each audio chunk in milliseconds (defaults to 5000).
</p></dd>
</dl>
<a name="Example-3"></a>
<h4 class="subsection">22.22.2 Example<span class="pull-right"><a class="anchor hidden-xs" href="#Example-3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Example-3" aria-hidden="true">TOC</a></span></h4>
<div class="example">
<pre class="example">ffmpeg -f v4l2 -i /dev/video0 \
-f alsa -i hw:0 \
-map 0:0 \
-c:v libvpx-vp9 \
-s 640x360 -keyint_min 30 -g 30 \
-f webm_chunk \
-header webm_live_video_360.hdr \
-chunk_start_index 1 \
webm_live_video_360_%d.chk \
-map 1:0 \
-c:a libvorbis \
-b:a 128k \
-f webm_chunk \
-header webm_live_audio_128.hdr \
-chunk_start_index 1 \
-audio_chunk_duration 1000 \
webm_live_audio_128_%d.chk
</pre></div>
<a name="Metadata-1"></a>
<h2 class="chapter">23 Metadata<span class="pull-right"><a class="anchor hidden-xs" href="#Metadata-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Metadata-1" aria-hidden="true">TOC</a></span></h2>
<p>FFmpeg is able to dump metadata from media files into a simple UTF-8-encoded
INI-like text file and then load it back using the metadata muxer/demuxer.
</p>
<p>The file format is as follows:
</p><ol>
<li> A file consists of a header and a number of metadata tags divided into sections,
each on its own line.
</li><li> The header is a ‘<samp>;FFMETADATA</samp>’ string, followed by a version number (now 1).
</li><li> Metadata tags are of the form ‘<samp>key=value</samp>’
</li><li> Immediately after header follows global metadata
</li><li> After global metadata there may be sections with per-stream/per-chapter
metadata.
</li><li> A section starts with the section name in uppercase (i.e. STREAM or CHAPTER) in
brackets (‘<samp>[</samp>’, ‘<samp>]</samp>’) and ends with next section or end of file.
</li><li> At the beginning of a chapter section there may be an optional timebase to be
used for start/end values. It must be in form
‘<samp>TIMEBASE=<var>num</var>/<var>den</var></samp>’, where <var>num</var> and <var>den</var> are
integers. If the timebase is missing then start/end times are assumed to
be in milliseconds.
<p>Next a chapter section must contain chapter start and end times in form
‘<samp>START=<var>num</var></samp>’, ‘<samp>END=<var>num</var></samp>’, where <var>num</var> is a positive
integer.
</p>
</li><li> Empty lines and lines starting with ‘<samp>;</samp>’ or ‘<samp>#</samp>’ are ignored.
</li><li> Metadata keys or values containing special characters (‘<samp>=</samp>’, ‘<samp>;</samp>’,
‘<samp>#</samp>’, ‘<samp>\</samp>’ and a newline) must be escaped with a backslash ‘<samp>\</samp>’.
</li><li> Note that whitespace in metadata (e.g. ‘<samp>foo = bar</samp>’) is considered to be
a part of the tag (in the example above key is ‘<samp>foo </samp>’, value is
‘<samp> bar</samp>’).
</li></ol>
<p>A ffmetadata file might look like this:
</p><div class="example">
<pre class="example">;FFMETADATA1
title=bike\\shed
;this is a comment
artist=FFmpeg troll team
[CHAPTER]
TIMEBASE=1/1000
START=0
#chapter ends at 0:01:00
END=60000
title=chapter \#1
[STREAM]
title=multi\
line
</pre></div>
<p>By using the ffmetadata muxer and demuxer it is possible to extract
metadata from an input file to an ffmetadata file, and then transcode
the file into an output file with the edited ffmetadata file.
</p>
<p>Extracting an ffmetadata file with <samp>ffmpeg</samp> goes as follows:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f ffmetadata FFMETADATAFILE
</pre></div>
<p>Reinserting edited metadata information from the FFMETADATAFILE file can
be done as:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -i FFMETADATAFILE -map_metadata 1 -codec copy OUTPUT
</pre></div>
<a name="Protocols"></a>
<h2 class="chapter">24 Protocols<span class="pull-right"><a class="anchor hidden-xs" href="#Protocols" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Protocols" aria-hidden="true">TOC</a></span></h2>
<p>Protocols are configured elements in FFmpeg that enable access to
resources that require specific protocols.
</p>
<p>When you configure your FFmpeg build, all the supported protocols are
enabled by default. You can list all available ones using the
configure option "–list-protocols".
</p>
<p>You can disable all the protocols using the configure option
"–disable-protocols", and selectively enable a protocol using the
option "–enable-protocol=<var>PROTOCOL</var>", or you can disable a
particular protocol using the option
"–disable-protocol=<var>PROTOCOL</var>".
</p>
<p>The option "-protocols" of the ff* tools will display the list of
supported protocols.
</p>
<p>A description of the currently available protocols follows.
</p>
<a name="async"></a>
<h3 class="section">24.1 async<span class="pull-right"><a class="anchor hidden-xs" href="#async" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-async" aria-hidden="true">TOC</a></span></h3>
<p>Asynchronous data filling wrapper for input stream.
</p>
<p>Fill data in a background thread, to decouple I/O operation from demux thread.
</p>
<div class="example">
<pre class="example">async:<var>URL</var>
async:http://host/resource
async:cache:http://host/resource
</pre></div>
<a name="bluray"></a>
<h3 class="section">24.2 bluray<span class="pull-right"><a class="anchor hidden-xs" href="#bluray" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bluray" aria-hidden="true">TOC</a></span></h3>
<p>Read BluRay playlist.
</p>
<p>The accepted options are:
</p><dl compact="compact">
<dt><samp>angle</samp></dt>
<dd><p>BluRay angle
</p>
</dd>
<dt><samp>chapter</samp></dt>
<dd><p>Start chapter (1...N)
</p>
</dd>
<dt><samp>playlist</samp></dt>
<dd><p>Playlist to read (BDMV/PLAYLIST/?????.mpls)
</p>
</dd>
</dl>
<p>Examples:
</p>
<p>Read longest playlist from BluRay mounted to /mnt/bluray:
</p><div class="example">
<pre class="example">bluray:/mnt/bluray
</pre></div>
<p>Read angle 2 of playlist 4 from BluRay mounted to /mnt/bluray, start from chapter 2:
</p><div class="example">
<pre class="example">-playlist 4 -angle 2 -chapter 2 bluray:/mnt/bluray
</pre></div>
<a name="cache"></a>
<h3 class="section">24.3 cache<span class="pull-right"><a class="anchor hidden-xs" href="#cache" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-cache" aria-hidden="true">TOC</a></span></h3>
<p>Caching wrapper for input stream.
</p>
<p>Cache the input stream to temporary file. It brings seeking capability to live streams.
</p>
<div class="example">
<pre class="example">cache:<var>URL</var>
</pre></div>
<a name="concat-2"></a>
<h3 class="section">24.4 concat<span class="pull-right"><a class="anchor hidden-xs" href="#concat-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-concat-2" aria-hidden="true">TOC</a></span></h3>
<p>Physical concatenation protocol.
</p>
<p>Read and seek from many resources in sequence as if they were
a unique resource.
</p>
<p>A URL accepted by this protocol has the syntax:
</p><div class="example">
<pre class="example">concat:<var>URL1</var>|<var>URL2</var>|...|<var>URLN</var>
</pre></div>
<p>where <var>URL1</var>, <var>URL2</var>, ..., <var>URLN</var> are the urls of the
resource to be concatenated, each one possibly specifying a distinct
protocol.
</p>
<p>For example to read a sequence of files <samp>split1.mpeg</samp>,
<samp>split2.mpeg</samp>, <samp>split3.mpeg</samp> with <code>ffplay</code> use the
command:
</p><div class="example">
<pre class="example">ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg
</pre></div>
<p>Note that you may need to escape the character "|" which is special for
many shells.
</p>
<a name="crypto"></a>
<h3 class="section">24.5 crypto<span class="pull-right"><a class="anchor hidden-xs" href="#crypto" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-crypto" aria-hidden="true">TOC</a></span></h3>
<p>AES-encrypted stream reading protocol.
</p>
<p>The accepted options are:
</p><dl compact="compact">
<dt><samp>key</samp></dt>
<dd><p>Set the AES decryption key binary block from given hexadecimal representation.
</p>
</dd>
<dt><samp>iv</samp></dt>
<dd><p>Set the AES decryption initialization vector binary block from given hexadecimal representation.
</p></dd>
</dl>
<p>Accepted URL formats:
</p><div class="example">
<pre class="example">crypto:<var>URL</var>
crypto+<var>URL</var>
</pre></div>
<a name="data"></a>
<h3 class="section">24.6 data<span class="pull-right"><a class="anchor hidden-xs" href="#data" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-data" aria-hidden="true">TOC</a></span></h3>
<p>Data in-line in the URI. See <a href="http://en.wikipedia.org/wiki/Data_URI_scheme">http://en.wikipedia.org/wiki/Data_URI_scheme</a>.
</p>
<p>For example, to convert a GIF file given inline with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png
</pre></div>
<a name="file"></a>
<h3 class="section">24.7 file<span class="pull-right"><a class="anchor hidden-xs" href="#file" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-file" aria-hidden="true">TOC</a></span></h3>
<p>File access protocol.
</p>
<p>Read from or write to a file.
</p>
<p>A file URL can have the form:
</p><div class="example">
<pre class="example">file:<var>filename</var>
</pre></div>
<p>where <var>filename</var> is the path of the file to read.
</p>
<p>An URL that does not have a protocol prefix will be assumed to be a
file URL. Depending on the build, an URL that looks like a Windows
path with the drive letter at the beginning will also be assumed to be
a file URL (usually not the case in builds for unix-like systems).
</p>
<p>For example to read from a file <samp>input.mpeg</samp> with <code>ffmpeg</code>
use the command:
</p><div class="example">
<pre class="example">ffmpeg -i file:input.mpeg output.mpeg
</pre></div>
<p>This protocol accepts the following options:
</p>
<dl compact="compact">
<dt><samp>truncate</samp></dt>
<dd><p>Truncate existing files on write, if set to 1. A value of 0 prevents
truncating. Default value is 1.
</p>
</dd>
<dt><samp>blocksize</samp></dt>
<dd><p>Set I/O operation maximum block size, in bytes. Default value is
<code>INT_MAX</code>, which results in not limiting the requested block size.
Setting this value reasonably low improves user termination request reaction
time, which is valuable for files on slow medium.
</p></dd>
</dl>
<a name="ftp"></a>
<h3 class="section">24.8 ftp<span class="pull-right"><a class="anchor hidden-xs" href="#ftp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ftp" aria-hidden="true">TOC</a></span></h3>
<p>FTP (File Transfer Protocol).
</p>
<p>Read from or write to remote resources using FTP protocol.
</p>
<p>Following syntax is required.
</p><div class="example">
<pre class="example">ftp://[user[:password]@]server[:port]/path/to/remote/resource.mpeg
</pre></div>
<p>This protocol accepts the following options.
</p>
<dl compact="compact">
<dt><samp>timeout</samp></dt>
<dd><p>Set timeout in microseconds of socket I/O operations used by the underlying low level
operation. By default it is set to -1, which means that the timeout is
not specified.
</p>
</dd>
<dt><samp>ftp-anonymous-password</samp></dt>
<dd><p>Password used when login as anonymous user. Typically an e-mail address
should be used.
</p>
</dd>
<dt><samp>ftp-write-seekable</samp></dt>
<dd><p>Control seekability of connection during encoding. If set to 1 the
resource is supposed to be seekable, if set to 0 it is assumed not
to be seekable. Default value is 0.
</p></dd>
</dl>
<p>NOTE: Protocol can be used as output, but it is recommended to not do
it, unless special care is taken (tests, customized server configuration
etc.). Different FTP servers behave in different way during seek
operation. ff* tools may produce incomplete content due to server limitations.
</p>
<a name="gopher"></a>
<h3 class="section">24.9 gopher<span class="pull-right"><a class="anchor hidden-xs" href="#gopher" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-gopher" aria-hidden="true">TOC</a></span></h3>
<p>Gopher protocol.
</p>
<a name="hls-2"></a>
<h3 class="section">24.10 hls<span class="pull-right"><a class="anchor hidden-xs" href="#hls-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hls-2" aria-hidden="true">TOC</a></span></h3>
<p>Read Apple HTTP Live Streaming compliant segmented stream as
a uniform one. The M3U8 playlists describing the segments can be
remote HTTP resources or local files, accessed using the standard
file protocol.
The nested protocol is declared by specifying
"+<var>proto</var>" after the hls URI scheme name, where <var>proto</var>
is either "file" or "http".
</p>
<div class="example">
<pre class="example">hls+http://host/path/to/remote/resource.m3u8
hls+file://path/to/local/resource.m3u8
</pre></div>
<p>Using this protocol is discouraged - the hls demuxer should work
just as well (if not, please report the issues) and is more complete.
To use the hls demuxer instead, simply use the direct URLs to the
m3u8 files.
</p>
<a name="http"></a>
<h3 class="section">24.11 http<span class="pull-right"><a class="anchor hidden-xs" href="#http" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-http" aria-hidden="true">TOC</a></span></h3>
<p>HTTP (Hyper Text Transfer Protocol).
</p>
<p>This protocol accepts the following options:
</p>
<dl compact="compact">
<dt><samp>seekable</samp></dt>
<dd><p>Control seekability of connection. If set to 1 the resource is
supposed to be seekable, if set to 0 it is assumed not to be seekable,
if set to -1 it will try to autodetect if it is seekable. Default
value is -1.
</p>
</dd>
<dt><samp>chunked_post</samp></dt>
<dd><p>If set to 1 use chunked Transfer-Encoding for posts, default is 1.
</p>
</dd>
<dt><samp>content_type</samp></dt>
<dd><p>Set a specific content type for the POST messages.
</p>
</dd>
<dt><samp>headers</samp></dt>
<dd><p>Set custom HTTP headers, can override built in default headers. The
value must be a string encoding the headers.
</p>
</dd>
<dt><samp>multiple_requests</samp></dt>
<dd><p>Use persistent connections if set to 1, default is 0.
</p>
</dd>
<dt><samp>post_data</samp></dt>
<dd><p>Set custom HTTP post data.
</p>
</dd>
<dt><samp>user-agent</samp></dt>
<dt><samp>user_agent</samp></dt>
<dd><p>Override the User-Agent header. If not specified the protocol will use a
string describing the libavformat build. ("Lavf/<version>")
</p>
</dd>
<dt><samp>timeout</samp></dt>
<dd><p>Set timeout in microseconds of socket I/O operations used by the underlying low level
operation. By default it is set to -1, which means that the timeout is
not specified.
</p>
</dd>
<dt><samp>mime_type</samp></dt>
<dd><p>Export the MIME type.
</p>
</dd>
<dt><samp>icy</samp></dt>
<dd><p>If set to 1 request ICY (SHOUTcast) metadata from the server. If the server
supports this, the metadata has to be retrieved by the application by reading
the <samp>icy_metadata_headers</samp> and <samp>icy_metadata_packet</samp> options.
The default is 1.
</p>
</dd>
<dt><samp>icy_metadata_headers</samp></dt>
<dd><p>If the server supports ICY metadata, this contains the ICY-specific HTTP reply
headers, separated by newline characters.
</p>
</dd>
<dt><samp>icy_metadata_packet</samp></dt>
<dd><p>If the server supports ICY metadata, and <samp>icy</samp> was set to 1, this
contains the last non-empty metadata packet sent by the server. It should be
polled in regular intervals by applications interested in mid-stream metadata
updates.
</p>
</dd>
<dt><samp>cookies</samp></dt>
<dd><p>Set the cookies to be sent in future requests. The format of each cookie is the
same as the value of a Set-Cookie HTTP response field. Multiple cookies can be
delimited by a newline character.
</p>
</dd>
<dt><samp>offset</samp></dt>
<dd><p>Set initial byte offset.
</p>
</dd>
<dt><samp>end_offset</samp></dt>
<dd><p>Try to limit the request to bytes preceding this offset.
</p>
</dd>
<dt><samp>method</samp></dt>
<dd><p>When used as a client option it sets the HTTP method for the request.
</p>
<p>When used as a server option it sets the HTTP method that is going to be
expected from the client(s).
If the expected and the received HTTP method do not match the client will
be given a Bad Request response.
When unset the HTTP method is not checked for now. This will be replaced by
autodetection in the future.
</p>
</dd>
<dt><samp>listen</samp></dt>
<dd><p>If set to 1 enables experimental HTTP server. This can be used to send data when
used as an output option, or read data from a client with HTTP POST when used as
an input option.
If set to 2 enables experimental mutli-client HTTP server. This is not yet implemented
in ffmpeg.c or ffserver.c and thus must not be used as a command line option.
</p><div class="example">
<pre class="example"># Server side (sending):
ffmpeg -i somefile.ogg -c copy -listen 1 -f ogg http://<var>server</var>:<var>port</var>
# Client side (receiving):
ffmpeg -i http://<var>server</var>:<var>port</var> -c copy somefile.ogg
# Client can also be done with wget:
wget http://<var>server</var>:<var>port</var> -O somefile.ogg
# Server side (receiving):
ffmpeg -listen 1 -i http://<var>server</var>:<var>port</var> -c copy somefile.ogg
# Client side (sending):
ffmpeg -i somefile.ogg -chunked_post 0 -c copy -f ogg http://<var>server</var>:<var>port</var>
# Client can also be done with wget:
wget --post-file=somefile.ogg http://<var>server</var>:<var>port</var>
</pre></div>
</dd>
</dl>
<a name="HTTP-Cookies"></a>
<h4 class="subsection">24.11.1 HTTP Cookies<span class="pull-right"><a class="anchor hidden-xs" href="#HTTP-Cookies" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-HTTP-Cookies" aria-hidden="true">TOC</a></span></h4>
<p>Some HTTP requests will be denied unless cookie values are passed in with the
request. The <samp>cookies</samp> option allows these cookies to be specified. At
the very least, each cookie must specify a value along with a path and domain.
HTTP requests that match both the domain and path will automatically include the
cookie value in the HTTP Cookie header field. Multiple cookies can be delimited
by a newline.
</p>
<p>The required syntax to play a stream specifying a cookie is:
</p><div class="example">
<pre class="example">ffplay -cookies "nlqptid=nltid=tsn; path=/; domain=somedomain.com;" http://somedomain.com/somestream.m3u8
</pre></div>
<a name="Icecast"></a>
<h3 class="section">24.12 Icecast<span class="pull-right"><a class="anchor hidden-xs" href="#Icecast" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Icecast" aria-hidden="true">TOC</a></span></h3>
<p>Icecast protocol (stream to Icecast servers)
</p>
<p>This protocol accepts the following options:
</p>
<dl compact="compact">
<dt><samp>ice_genre</samp></dt>
<dd><p>Set the stream genre.
</p>
</dd>
<dt><samp>ice_name</samp></dt>
<dd><p>Set the stream name.
</p>
</dd>
<dt><samp>ice_description</samp></dt>
<dd><p>Set the stream description.
</p>
</dd>
<dt><samp>ice_url</samp></dt>
<dd><p>Set the stream website URL.
</p>
</dd>
<dt><samp>ice_public</samp></dt>
<dd><p>Set if the stream should be public.
The default is 0 (not public).
</p>
</dd>
<dt><samp>user_agent</samp></dt>
<dd><p>Override the User-Agent header. If not specified a string of the form
"Lavf/<version>" will be used.
</p>
</dd>
<dt><samp>password</samp></dt>
<dd><p>Set the Icecast mountpoint password.
</p>
</dd>
<dt><samp>content_type</samp></dt>
<dd><p>Set the stream content type. This must be set if it is different from
audio/mpeg.
</p>
</dd>
<dt><samp>legacy_icecast</samp></dt>
<dd><p>This enables support for Icecast versions < 2.4.0, that do not support the
HTTP PUT method but the SOURCE method.
</p>
</dd>
</dl>
<div class="example">
<pre class="example">icecast://[<var>username</var>[:<var>password</var>]@]<var>server</var>:<var>port</var>/<var>mountpoint</var>
</pre></div>
<a name="mmst"></a>
<h3 class="section">24.13 mmst<span class="pull-right"><a class="anchor hidden-xs" href="#mmst" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mmst" aria-hidden="true">TOC</a></span></h3>
<p>MMS (Microsoft Media Server) protocol over TCP.
</p>
<a name="mmsh"></a>
<h3 class="section">24.14 mmsh<span class="pull-right"><a class="anchor hidden-xs" href="#mmsh" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mmsh" aria-hidden="true">TOC</a></span></h3>
<p>MMS (Microsoft Media Server) protocol over HTTP.
</p>
<p>The required syntax is:
</p><div class="example">
<pre class="example">mmsh://<var>server</var>[:<var>port</var>][/<var>app</var>][/<var>playpath</var>]
</pre></div>
<a name="md5-2"></a>
<h3 class="section">24.15 md5<span class="pull-right"><a class="anchor hidden-xs" href="#md5-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-md5-2" aria-hidden="true">TOC</a></span></h3>
<p>MD5 output protocol.
</p>
<p>Computes the MD5 hash of the data to be written, and on close writes
this to the designated output or stdout if none is specified. It can
be used to test muxers without writing an actual file.
</p>
<p>Some examples follow.
</p><div class="example">
<pre class="example"># Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
ffmpeg -i input.flv -f avi -y md5:output.avi.md5
# Write the MD5 hash of the encoded AVI file to stdout.
ffmpeg -i input.flv -f avi -y md5:
</pre></div>
<p>Note that some formats (typically MOV) require the output protocol to
be seekable, so they will fail with the MD5 output protocol.
</p>
<a name="pipe"></a>
<h3 class="section">24.16 pipe<span class="pull-right"><a class="anchor hidden-xs" href="#pipe" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pipe" aria-hidden="true">TOC</a></span></h3>
<p>UNIX pipe access protocol.
</p>
<p>Read and write from UNIX pipes.
</p>
<p>The accepted syntax is:
</p><div class="example">
<pre class="example">pipe:[<var>number</var>]
</pre></div>
<p><var>number</var> is the number corresponding to the file descriptor of the
pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If <var>number</var>
is not specified, by default the stdout file descriptor will be used
for writing, stdin for reading.
</p>
<p>For example to read from stdin with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">cat test.wav | ffmpeg -i pipe:0
# ...this is the same as...
cat test.wav | ffmpeg -i pipe:
</pre></div>
<p>For writing to stdout with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
# ...this is the same as...
ffmpeg -i test.wav -f avi pipe: | cat > test.avi
</pre></div>
<p>This protocol accepts the following options:
</p>
<dl compact="compact">
<dt><samp>blocksize</samp></dt>
<dd><p>Set I/O operation maximum block size, in bytes. Default value is
<code>INT_MAX</code>, which results in not limiting the requested block size.
Setting this value reasonably low improves user termination request reaction
time, which is valuable if data transmission is slow.
</p></dd>
</dl>
<p>Note that some formats (typically MOV), require the output protocol to
be seekable, so they will fail with the pipe output protocol.
</p>
<a name="rtmp"></a>
<h3 class="section">24.17 rtmp<span class="pull-right"><a class="anchor hidden-xs" href="#rtmp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmp" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Messaging Protocol.
</p>
<p>The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia
content across a TCP/IP network.
</p>
<p>The required syntax is:
</p><div class="example">
<pre class="example">rtmp://[<var>username</var>:<var>password</var>@]<var>server</var>[:<var>port</var>][/<var>app</var>][/<var>instance</var>][/<var>playpath</var>]
</pre></div>
<p>The accepted parameters are:
</p><dl compact="compact">
<dt><samp>username</samp></dt>
<dd><p>An optional username (mostly for publishing).
</p>
</dd>
<dt><samp>password</samp></dt>
<dd><p>An optional password (mostly for publishing).
</p>
</dd>
<dt><samp>server</samp></dt>
<dd><p>The address of the RTMP server.
</p>
</dd>
<dt><samp>port</samp></dt>
<dd><p>The number of the TCP port to use (by default is 1935).
</p>
</dd>
<dt><samp>app</samp></dt>
<dd><p>It is the name of the application to access. It usually corresponds to
the path where the application is installed on the RTMP server
(e.g. <samp>/ondemand/</samp>, <samp>/flash/live/</samp>, etc.). You can override
the value parsed from the URI through the <code>rtmp_app</code> option, too.
</p>
</dd>
<dt><samp>playpath</samp></dt>
<dd><p>It is the path or name of the resource to play with reference to the
application specified in <var>app</var>, may be prefixed by "mp4:". You
can override the value parsed from the URI through the <code>rtmp_playpath</code>
option, too.
</p>
</dd>
<dt><samp>listen</samp></dt>
<dd><p>Act as a server, listening for an incoming connection.
</p>
</dd>
<dt><samp>timeout</samp></dt>
<dd><p>Maximum time to wait for the incoming connection. Implies listen.
</p></dd>
</dl>
<p>Additionally, the following parameters can be set via command line options
(or in code via <code>AVOption</code>s):
</p><dl compact="compact">
<dt><samp>rtmp_app</samp></dt>
<dd><p>Name of application to connect on the RTMP server. This option
overrides the parameter specified in the URI.
</p>
</dd>
<dt><samp>rtmp_buffer</samp></dt>
<dd><p>Set the client buffer time in milliseconds. The default is 3000.
</p>
</dd>
<dt><samp>rtmp_conn</samp></dt>
<dd><p>Extra arbitrary AMF connection parameters, parsed from a string,
e.g. like <code>B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0</code>.
Each value is prefixed by a single character denoting the type,
B for Boolean, N for number, S for string, O for object, or Z for null,
followed by a colon. For Booleans the data must be either 0 or 1 for
FALSE or TRUE, respectively. Likewise for Objects the data must be 0 or
1 to end or begin an object, respectively. Data items in subobjects may
be named, by prefixing the type with ’N’ and specifying the name before
the value (i.e. <code>NB:myFlag:1</code>). This option may be used multiple
times to construct arbitrary AMF sequences.
</p>
</dd>
<dt><samp>rtmp_flashver</samp></dt>
<dd><p>Version of the Flash plugin used to run the SWF player. The default
is LNX 9,0,124,2. (When publishing, the default is FMLE/3.0 (compatible;
<libavformat version>).)
</p>
</dd>
<dt><samp>rtmp_flush_interval</samp></dt>
<dd><p>Number of packets flushed in the same request (RTMPT only). The default
is 10.
</p>
</dd>
<dt><samp>rtmp_live</samp></dt>
<dd><p>Specify that the media is a live stream. No resuming or seeking in
live streams is possible. The default value is <code>any</code>, which means the
subscriber first tries to play the live stream specified in the
playpath. If a live stream of that name is not found, it plays the
recorded stream. The other possible values are <code>live</code> and
<code>recorded</code>.
</p>
</dd>
<dt><samp>rtmp_pageurl</samp></dt>
<dd><p>URL of the web page in which the media was embedded. By default no
value will be sent.
</p>
</dd>
<dt><samp>rtmp_playpath</samp></dt>
<dd><p>Stream identifier to play or to publish. This option overrides the
parameter specified in the URI.
</p>
</dd>
<dt><samp>rtmp_subscribe</samp></dt>
<dd><p>Name of live stream to subscribe to. By default no value will be sent.
It is only sent if the option is specified or if rtmp_live
is set to live.
</p>
</dd>
<dt><samp>rtmp_swfhash</samp></dt>
<dd><p>SHA256 hash of the decompressed SWF file (32 bytes).
</p>
</dd>
<dt><samp>rtmp_swfsize</samp></dt>
<dd><p>Size of the decompressed SWF file, required for SWFVerification.
</p>
</dd>
<dt><samp>rtmp_swfurl</samp></dt>
<dd><p>URL of the SWF player for the media. By default no value will be sent.
</p>
</dd>
<dt><samp>rtmp_swfverify</samp></dt>
<dd><p>URL to player swf file, compute hash/size automatically.
</p>
</dd>
<dt><samp>rtmp_tcurl</samp></dt>
<dd><p>URL of the target stream. Defaults to proto://host[:port]/app.
</p>
</dd>
</dl>
<p>For example to read with <code>ffplay</code> a multimedia resource named
"sample" from the application "vod" from an RTMP server "myserver":
</p><div class="example">
<pre class="example">ffplay rtmp://myserver/vod/sample
</pre></div>
<p>To publish to a password protected server, passing the playpath and
app names separately:
</p><div class="example">
<pre class="example">ffmpeg -re -i <input> -f flv -rtmp_playpath some/long/path -rtmp_app long/app/name rtmp://username:password@myserver/
</pre></div>
<a name="rtmpe"></a>
<h3 class="section">24.18 rtmpe<span class="pull-right"><a class="anchor hidden-xs" href="#rtmpe" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmpe" aria-hidden="true">TOC</a></span></h3>
<p>Encrypted Real-Time Messaging Protocol.
</p>
<p>The Encrypted Real-Time Messaging Protocol (RTMPE) is used for
streaming multimedia content within standard cryptographic primitives,
consisting of Diffie-Hellman key exchange and HMACSHA256, generating
a pair of RC4 keys.
</p>
<a name="rtmps"></a>
<h3 class="section">24.19 rtmps<span class="pull-right"><a class="anchor hidden-xs" href="#rtmps" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmps" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Messaging Protocol over a secure SSL connection.
</p>
<p>The Real-Time Messaging Protocol (RTMPS) is used for streaming
multimedia content across an encrypted connection.
</p>
<a name="rtmpt"></a>
<h3 class="section">24.20 rtmpt<span class="pull-right"><a class="anchor hidden-xs" href="#rtmpt" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmpt" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Messaging Protocol tunneled through HTTP.
</p>
<p>The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used
for streaming multimedia content within HTTP requests to traverse
firewalls.
</p>
<a name="rtmpte"></a>
<h3 class="section">24.21 rtmpte<span class="pull-right"><a class="anchor hidden-xs" href="#rtmpte" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmpte" aria-hidden="true">TOC</a></span></h3>
<p>Encrypted Real-Time Messaging Protocol tunneled through HTTP.
</p>
<p>The Encrypted Real-Time Messaging Protocol tunneled through HTTP (RTMPTE)
is used for streaming multimedia content within HTTP requests to traverse
firewalls.
</p>
<a name="rtmpts"></a>
<h3 class="section">24.22 rtmpts<span class="pull-right"><a class="anchor hidden-xs" href="#rtmpts" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtmpts" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Messaging Protocol tunneled through HTTPS.
</p>
<p>The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is used
for streaming multimedia content within HTTPS requests to traverse
firewalls.
</p>
<a name="libsmbclient"></a>
<h3 class="section">24.23 libsmbclient<span class="pull-right"><a class="anchor hidden-xs" href="#libsmbclient" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libsmbclient" aria-hidden="true">TOC</a></span></h3>
<p>libsmbclient permits one to manipulate CIFS/SMB network resources.
</p>
<p>Following syntax is required.
</p>
<div class="example">
<pre class="example">smb://[[domain:]user[:password@]]server[/share[/path[/file]]]
</pre></div>
<p>This protocol accepts the following options.
</p>
<dl compact="compact">
<dt><samp>timeout</samp></dt>
<dd><p>Set timeout in miliseconds of socket I/O operations used by the underlying
low level operation. By default it is set to -1, which means that the timeout
is not specified.
</p>
</dd>
<dt><samp>truncate</samp></dt>
<dd><p>Truncate existing files on write, if set to 1. A value of 0 prevents
truncating. Default value is 1.
</p>
</dd>
<dt><samp>workgroup</samp></dt>
<dd><p>Set the workgroup used for making connections. By default workgroup is not specified.
</p>
</dd>
</dl>
<p>For more information see: <a href="http://www.samba.org/">http://www.samba.org/</a>.
</p>
<a name="libssh"></a>
<h3 class="section">24.24 libssh<span class="pull-right"><a class="anchor hidden-xs" href="#libssh" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libssh" aria-hidden="true">TOC</a></span></h3>
<p>Secure File Transfer Protocol via libssh
</p>
<p>Read from or write to remote resources using SFTP protocol.
</p>
<p>Following syntax is required.
</p>
<div class="example">
<pre class="example">sftp://[user[:password]@]server[:port]/path/to/remote/resource.mpeg
</pre></div>
<p>This protocol accepts the following options.
</p>
<dl compact="compact">
<dt><samp>timeout</samp></dt>
<dd><p>Set timeout of socket I/O operations used by the underlying low level
operation. By default it is set to -1, which means that the timeout
is not specified.
</p>
</dd>
<dt><samp>truncate</samp></dt>
<dd><p>Truncate existing files on write, if set to 1. A value of 0 prevents
truncating. Default value is 1.
</p>
</dd>
<dt><samp>private_key</samp></dt>
<dd><p>Specify the path of the file containing private key to use during authorization.
By default libssh searches for keys in the <samp>~/.ssh/</samp> directory.
</p>
</dd>
</dl>
<p>Example: Play a file stored on remote server.
</p>
<div class="example">
<pre class="example">ffplay sftp://user:password@server_address:22/home/user/resource.mpeg
</pre></div>
<a name="librtmp-rtmp_002c-rtmpe_002c-rtmps_002c-rtmpt_002c-rtmpte"></a>
<h3 class="section">24.25 librtmp rtmp, rtmpe, rtmps, rtmpt, rtmpte<span class="pull-right"><a class="anchor hidden-xs" href="#librtmp-rtmp_002c-rtmpe_002c-rtmps_002c-rtmpt_002c-rtmpte" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-librtmp-rtmp_002c-rtmpe_002c-rtmps_002c-rtmpt_002c-rtmpte" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Messaging Protocol and its variants supported through
librtmp.
</p>
<p>Requires the presence of the librtmp headers and library during
configuration. You need to explicitly configure the build with
"–enable-librtmp". If enabled this will replace the native RTMP
protocol.
</p>
<p>This protocol provides most client functions and a few server
functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
variants of these encrypted types (RTMPTE, RTMPTS).
</p>
<p>The required syntax is:
</p><div class="example">
<pre class="example"><var>rtmp_proto</var>://<var>server</var>[:<var>port</var>][/<var>app</var>][/<var>playpath</var>] <var>options</var>
</pre></div>
<p>where <var>rtmp_proto</var> is one of the strings "rtmp", "rtmpt", "rtmpe",
"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
<var>server</var>, <var>port</var>, <var>app</var> and <var>playpath</var> have the same
meaning as specified for the RTMP native protocol.
<var>options</var> contains a list of space-separated options of the form
<var>key</var>=<var>val</var>.
</p>
<p>See the librtmp manual page (man 3 librtmp) for more information.
</p>
<p>For example, to stream a file in real-time to an RTMP server using
<code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -re -i myfile -f flv rtmp://myserver/live/mystream
</pre></div>
<p>To play the same stream using <code>ffplay</code>:
</p><div class="example">
<pre class="example">ffplay "rtmp://myserver/live/mystream live=1"
</pre></div>
<a name="rtp"></a>
<h3 class="section">24.26 rtp<span class="pull-right"><a class="anchor hidden-xs" href="#rtp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtp" aria-hidden="true">TOC</a></span></h3>
<p>Real-time Transport Protocol.
</p>
<p>The required syntax for an RTP URL is:
rtp://<var>hostname</var>[:<var>port</var>][?<var>option</var>=<var>val</var>...]
</p>
<p><var>port</var> specifies the RTP port to use.
</p>
<p>The following URL options are supported:
</p>
<dl compact="compact">
<dt><samp>ttl=<var>n</var></samp></dt>
<dd><p>Set the TTL (Time-To-Live) value (for multicast only).
</p>
</dd>
<dt><samp>rtcpport=<var>n</var></samp></dt>
<dd><p>Set the remote RTCP port to <var>n</var>.
</p>
</dd>
<dt><samp>localrtpport=<var>n</var></samp></dt>
<dd><p>Set the local RTP port to <var>n</var>.
</p>
</dd>
<dt><samp>localrtcpport=<var>n</var>'</samp></dt>
<dd><p>Set the local RTCP port to <var>n</var>.
</p>
</dd>
<dt><samp>pkt_size=<var>n</var></samp></dt>
<dd><p>Set max packet size (in bytes) to <var>n</var>.
</p>
</dd>
<dt><samp>connect=0|1</samp></dt>
<dd><p>Do a <code>connect()</code> on the UDP socket (if set to 1) or not (if set
to 0).
</p>
</dd>
<dt><samp>sources=<var>ip</var>[,<var>ip</var>]</samp></dt>
<dd><p>List allowed source IP addresses.
</p>
</dd>
<dt><samp>block=<var>ip</var>[,<var>ip</var>]</samp></dt>
<dd><p>List disallowed (blocked) source IP addresses.
</p>
</dd>
<dt><samp>write_to_source=0|1</samp></dt>
<dd><p>Send packets to the source address of the latest received packet (if
set to 1) or to a default remote address (if set to 0).
</p>
</dd>
<dt><samp>localport=<var>n</var></samp></dt>
<dd><p>Set the local RTP port to <var>n</var>.
</p>
<p>This is a deprecated option. Instead, <samp>localrtpport</samp> should be
used.
</p>
</dd>
</dl>
<p>Important notes:
</p>
<ol>
<li> If <samp>rtcpport</samp> is not set the RTCP port will be set to the RTP
port value plus 1.
</li><li> If <samp>localrtpport</samp> (the local RTP port) is not set any available
port will be used for the local RTP and RTCP ports.
</li><li> If <samp>localrtcpport</samp> (the local RTCP port) is not set it will be
set to the local RTP port value plus 1.
</li></ol>
<a name="rtsp"></a>
<h3 class="section">24.27 rtsp<span class="pull-right"><a class="anchor hidden-xs" href="#rtsp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rtsp" aria-hidden="true">TOC</a></span></h3>
<p>Real-Time Streaming Protocol.
</p>
<p>RTSP is not technically a protocol handler in libavformat, it is a demuxer
and muxer. The demuxer supports both normal RTSP (with data transferred
over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
data transferred over RDT).
</p>
<p>The muxer can be used to send a stream using RTSP ANNOUNCE to a server
supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
<a href="https://github.com/revmischa/rtsp-server">RTSP server</a>).
</p>
<p>The required syntax for a RTSP url is:
</p><div class="example">
<pre class="example">rtsp://<var>hostname</var>[:<var>port</var>]/<var>path</var>
</pre></div>
<p>Options can be set on the <code>ffmpeg</code>/<code>ffplay</code> command
line, or set in code via <code>AVOption</code>s or in
<code>avformat_open_input</code>.
</p>
<p>The following options are supported.
</p>
<dl compact="compact">
<dt><samp>initial_pause</samp></dt>
<dd><p>Do not start playing the stream immediately if set to 1. Default value
is 0.
</p>
</dd>
<dt><samp>rtsp_transport</samp></dt>
<dd><p>Set RTSP transport protocols.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>udp</samp>’</dt>
<dd><p>Use UDP as lower transport protocol.
</p>
</dd>
<dt>‘<samp>tcp</samp>’</dt>
<dd><p>Use TCP (interleaving within the RTSP control channel) as lower
transport protocol.
</p>
</dd>
<dt>‘<samp>udp_multicast</samp>’</dt>
<dd><p>Use UDP multicast as lower transport protocol.
</p>
</dd>
<dt>‘<samp>http</samp>’</dt>
<dd><p>Use HTTP tunneling as lower transport protocol, which is useful for
passing proxies.
</p></dd>
</dl>
<p>Multiple lower transport protocols may be specified, in that case they are
tried one at a time (if the setup of one fails, the next one is tried).
For the muxer, only the ‘<samp>tcp</samp>’ and ‘<samp>udp</samp>’ options are supported.
</p>
</dd>
<dt><samp>rtsp_flags</samp></dt>
<dd><p>Set RTSP flags.
</p>
<p>The following values are accepted:
</p><dl compact="compact">
<dt>‘<samp>filter_src</samp>’</dt>
<dd><p>Accept packets only from negotiated peer address and port.
</p></dd>
<dt>‘<samp>listen</samp>’</dt>
<dd><p>Act as a server, listening for an incoming connection.
</p></dd>
<dt>‘<samp>prefer_tcp</samp>’</dt>
<dd><p>Try TCP for RTP transport first, if TCP is available as RTSP RTP transport.
</p></dd>
</dl>
<p>Default value is ‘<samp>none</samp>’.
</p>
</dd>
<dt><samp>allowed_media_types</samp></dt>
<dd><p>Set media types to accept from the server.
</p>
<p>The following flags are accepted:
</p><dl compact="compact">
<dt>‘<samp>video</samp>’</dt>
<dt>‘<samp>audio</samp>’</dt>
<dt>‘<samp>data</samp>’</dt>
</dl>
<p>By default it accepts all media types.
</p>
</dd>
<dt><samp>min_port</samp></dt>
<dd><p>Set minimum local UDP port. Default value is 5000.
</p>
</dd>
<dt><samp>max_port</samp></dt>
<dd><p>Set maximum local UDP port. Default value is 65000.
</p>
</dd>
<dt><samp>timeout</samp></dt>
<dd><p>Set maximum timeout (in seconds) to wait for incoming connections.
</p>
<p>A value of -1 means infinite (default). This option implies the
<samp>rtsp_flags</samp> set to ‘<samp>listen</samp>’.
</p>
</dd>
<dt><samp>reorder_queue_size</samp></dt>
<dd><p>Set number of packets to buffer for handling of reordered packets.
</p>
</dd>
<dt><samp>stimeout</samp></dt>
<dd><p>Set socket TCP I/O timeout in microseconds.
</p>
</dd>
<dt><samp>user-agent</samp></dt>
<dd><p>Override User-Agent header. If not specified, it defaults to the
libavformat identifier string.
</p></dd>
</dl>
<p>When receiving data over UDP, the demuxer tries to reorder received packets
(since they may arrive out of order, or packets may get lost totally). This
can be disabled by setting the maximum demuxing delay to zero (via
the <code>max_delay</code> field of AVFormatContext).
</p>
<p>When watching multi-bitrate Real-RTSP streams with <code>ffplay</code>, the
streams to display can be chosen with <code>-vst</code> <var>n</var> and
<code>-ast</code> <var>n</var> for video and audio respectively, and can be switched
on the fly by pressing <code>v</code> and <code>a</code>.
</p>
<a name="Examples-12"></a>
<h4 class="subsection">24.27.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-12" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-12" aria-hidden="true">TOC</a></span></h4>
<p>The following examples all make use of the <code>ffplay</code> and
<code>ffmpeg</code> tools.
</p>
<ul>
<li> Watch a stream over UDP, with a max reordering delay of 0.5 seconds:
<div class="example">
<pre class="example">ffplay -max_delay 500000 -rtsp_transport udp rtsp://server/video.mp4
</pre></div>
</li><li> Watch a stream tunneled over HTTP:
<div class="example">
<pre class="example">ffplay -rtsp_transport http rtsp://server/video.mp4
</pre></div>
</li><li> Send a stream in realtime to a RTSP server, for others to watch:
<div class="example">
<pre class="example">ffmpeg -re -i <var>input</var> -f rtsp -muxdelay 0.1 rtsp://server/live.sdp
</pre></div>
</li><li> Receive a stream in realtime:
<div class="example">
<pre class="example">ffmpeg -rtsp_flags listen -i rtsp://ownaddress/live.sdp <var>output</var>
</pre></div>
</li></ul>
<a name="sap"></a>
<h3 class="section">24.28 sap<span class="pull-right"><a class="anchor hidden-xs" href="#sap" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sap" aria-hidden="true">TOC</a></span></h3>
<p>Session Announcement Protocol (RFC 2974). This is not technically a
protocol handler in libavformat, it is a muxer and demuxer.
It is used for signalling of RTP streams, by announcing the SDP for the
streams regularly on a separate port.
</p>
<a name="Muxer"></a>
<h4 class="subsection">24.28.1 Muxer<span class="pull-right"><a class="anchor hidden-xs" href="#Muxer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Muxer" aria-hidden="true">TOC</a></span></h4>
<p>The syntax for a SAP url given to the muxer is:
</p><div class="example">
<pre class="example">sap://<var>destination</var>[:<var>port</var>][?<var>options</var>]
</pre></div>
<p>The RTP packets are sent to <var>destination</var> on port <var>port</var>,
or to port 5004 if no port is specified.
<var>options</var> is a <code>&</code>-separated list. The following options
are supported:
</p>
<dl compact="compact">
<dt><samp>announce_addr=<var>address</var></samp></dt>
<dd><p>Specify the destination IP address for sending the announcements to.
If omitted, the announcements are sent to the commonly used SAP
announcement multicast address 224.2.127.254 (sap.mcast.net), or
ff0e::2:7ffe if <var>destination</var> is an IPv6 address.
</p>
</dd>
<dt><samp>announce_port=<var>port</var></samp></dt>
<dd><p>Specify the port to send the announcements on, defaults to
9875 if not specified.
</p>
</dd>
<dt><samp>ttl=<var>ttl</var></samp></dt>
<dd><p>Specify the time to live value for the announcements and RTP packets,
defaults to 255.
</p>
</dd>
<dt><samp>same_port=<var>0|1</var></samp></dt>
<dd><p>If set to 1, send all RTP streams on the same port pair. If zero (the
default), all streams are sent on unique ports, with each stream on a
port 2 numbers higher than the previous.
VLC/Live555 requires this to be set to 1, to be able to receive the stream.
The RTP stack in libavformat for receiving requires all streams to be sent
on unique ports.
</p></dd>
</dl>
<p>Example command lines follow.
</p>
<p>To broadcast a stream on the local subnet, for watching in VLC:
</p>
<div class="example">
<pre class="example">ffmpeg -re -i <var>input</var> -f sap sap://224.0.0.255?same_port=1
</pre></div>
<p>Similarly, for watching in <code>ffplay</code>:
</p>
<div class="example">
<pre class="example">ffmpeg -re -i <var>input</var> -f sap sap://224.0.0.255
</pre></div>
<p>And for watching in <code>ffplay</code>, over IPv6:
</p>
<div class="example">
<pre class="example">ffmpeg -re -i <var>input</var> -f sap sap://[ff0e::1:2:3:4]
</pre></div>
<a name="Demuxer"></a>
<h4 class="subsection">24.28.2 Demuxer<span class="pull-right"><a class="anchor hidden-xs" href="#Demuxer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Demuxer" aria-hidden="true">TOC</a></span></h4>
<p>The syntax for a SAP url given to the demuxer is:
</p><div class="example">
<pre class="example">sap://[<var>address</var>][:<var>port</var>]
</pre></div>
<p><var>address</var> is the multicast address to listen for announcements on,
if omitted, the default 224.2.127.254 (sap.mcast.net) is used. <var>port</var>
is the port that is listened on, 9875 if omitted.
</p>
<p>The demuxers listens for announcements on the given address and port.
Once an announcement is received, it tries to receive that particular stream.
</p>
<p>Example command lines follow.
</p>
<p>To play back the first stream announced on the normal SAP multicast address:
</p>
<div class="example">
<pre class="example">ffplay sap://
</pre></div>
<p>To play back the first stream announced on one the default IPv6 SAP multicast address:
</p>
<div class="example">
<pre class="example">ffplay sap://[ff0e::2:7ffe]
</pre></div>
<a name="sctp"></a>
<h3 class="section">24.29 sctp<span class="pull-right"><a class="anchor hidden-xs" href="#sctp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sctp" aria-hidden="true">TOC</a></span></h3>
<p>Stream Control Transmission Protocol.
</p>
<p>The accepted URL syntax is:
</p><div class="example">
<pre class="example">sctp://<var>host</var>:<var>port</var>[?<var>options</var>]
</pre></div>
<p>The protocol accepts the following options:
</p><dl compact="compact">
<dt><samp>listen</samp></dt>
<dd><p>If set to any value, listen for an incoming connection. Outgoing connection is done by default.
</p>
</dd>
<dt><samp>max_streams</samp></dt>
<dd><p>Set the maximum number of streams. By default no limit is set.
</p></dd>
</dl>
<a name="srtp"></a>
<h3 class="section">24.30 srtp<span class="pull-right"><a class="anchor hidden-xs" href="#srtp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-srtp" aria-hidden="true">TOC</a></span></h3>
<p>Secure Real-time Transport Protocol.
</p>
<p>The accepted options are:
</p><dl compact="compact">
<dt><samp>srtp_in_suite</samp></dt>
<dt><samp>srtp_out_suite</samp></dt>
<dd><p>Select input and output encoding suites.
</p>
<p>Supported values:
</p><dl compact="compact">
<dt>‘<samp>AES_CM_128_HMAC_SHA1_80</samp>’</dt>
<dt>‘<samp>SRTP_AES128_CM_HMAC_SHA1_80</samp>’</dt>
<dt>‘<samp>AES_CM_128_HMAC_SHA1_32</samp>’</dt>
<dt>‘<samp>SRTP_AES128_CM_HMAC_SHA1_32</samp>’</dt>
</dl>
</dd>
<dt><samp>srtp_in_params</samp></dt>
<dt><samp>srtp_out_params</samp></dt>
<dd><p>Set input and output encoding parameters, which are expressed by a
base64-encoded representation of a binary block. The first 16 bytes of
this binary block are used as master key, the following 14 bytes are
used as master salt.
</p></dd>
</dl>
<a name="subfile"></a>
<h3 class="section">24.31 subfile<span class="pull-right"><a class="anchor hidden-xs" href="#subfile" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-subfile" aria-hidden="true">TOC</a></span></h3>
<p>Virtually extract a segment of a file or another stream.
The underlying stream must be seekable.
</p>
<p>Accepted options:
</p><dl compact="compact">
<dt><samp>start</samp></dt>
<dd><p>Start offset of the extracted segment, in bytes.
</p></dd>
<dt><samp>end</samp></dt>
<dd><p>End offset of the extracted segment, in bytes.
</p></dd>
</dl>
<p>Examples:
</p>
<p>Extract a chapter from a DVD VOB file (start and end sectors obtained
externally and multiplied by 2048):
</p><div class="example">
<pre class="example">subfile,,start,153391104,end,268142592,,:/media/dvd/VIDEO_TS/VTS_08_1.VOB
</pre></div>
<p>Play an AVI file directly from a TAR archive:
</p><div class="example">
<pre class="example">subfile,,start,183241728,end,366490624,,:archive.tar
</pre></div>
<a name="tcp"></a>
<h3 class="section">24.32 tcp<span class="pull-right"><a class="anchor hidden-xs" href="#tcp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tcp" aria-hidden="true">TOC</a></span></h3>
<p>Transmission Control Protocol.
</p>
<p>The required syntax for a TCP url is:
</p><div class="example">
<pre class="example">tcp://<var>hostname</var>:<var>port</var>[?<var>options</var>]
</pre></div>
<p><var>options</var> contains a list of &-separated options of the form
<var>key</var>=<var>val</var>.
</p>
<p>The list of supported options follows.
</p>
<dl compact="compact">
<dt><samp>listen=<var>1|0</var></samp></dt>
<dd><p>Listen for an incoming connection. Default value is 0.
</p>
</dd>
<dt><samp>timeout=<var>microseconds</var></samp></dt>
<dd><p>Set raise error timeout, expressed in microseconds.
</p>
<p>This option is only relevant in read mode: if no data arrived in more
than this time interval, raise error.
</p>
</dd>
<dt><samp>listen_timeout=<var>milliseconds</var></samp></dt>
<dd><p>Set listen timeout, expressed in milliseconds.
</p></dd>
</dl>
<p>The following example shows how to setup a listening TCP connection
with <code>ffmpeg</code>, which is then accessed with <code>ffplay</code>:
</p><div class="example">
<pre class="example">ffmpeg -i <var>input</var> -f <var>format</var> tcp://<var>hostname</var>:<var>port</var>?listen
ffplay tcp://<var>hostname</var>:<var>port</var>
</pre></div>
<a name="tls"></a>
<h3 class="section">24.33 tls<span class="pull-right"><a class="anchor hidden-xs" href="#tls" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tls" aria-hidden="true">TOC</a></span></h3>
<p>Transport Layer Security (TLS) / Secure Sockets Layer (SSL)
</p>
<p>The required syntax for a TLS/SSL url is:
</p><div class="example">
<pre class="example">tls://<var>hostname</var>:<var>port</var>[?<var>options</var>]
</pre></div>
<p>The following parameters can be set via command line options
(or in code via <code>AVOption</code>s):
</p>
<dl compact="compact">
<dt><samp>ca_file, cafile=<var>filename</var></samp></dt>
<dd><p>A file containing certificate authority (CA) root certificates to treat
as trusted. If the linked TLS library contains a default this might not
need to be specified for verification to work, but not all libraries and
setups have defaults built in.
The file must be in OpenSSL PEM format.
</p>
</dd>
<dt><samp>tls_verify=<var>1|0</var></samp></dt>
<dd><p>If enabled, try to verify the peer that we are communicating with.
Note, if using OpenSSL, this currently only makes sure that the
peer certificate is signed by one of the root certificates in the CA
database, but it does not validate that the certificate actually
matches the host name we are trying to connect to. (With GnuTLS,
the host name is validated as well.)
</p>
<p>This is disabled by default since it requires a CA database to be
provided by the caller in many cases.
</p>
</dd>
<dt><samp>cert_file, cert=<var>filename</var></samp></dt>
<dd><p>A file containing a certificate to use in the handshake with the peer.
(When operating as server, in listen mode, this is more often required
by the peer, while client certificates only are mandated in certain
setups.)
</p>
</dd>
<dt><samp>key_file, key=<var>filename</var></samp></dt>
<dd><p>A file containing the private key for the certificate.
</p>
</dd>
<dt><samp>listen=<var>1|0</var></samp></dt>
<dd><p>If enabled, listen for connections on the provided port, and assume
the server role in the handshake instead of the client role.
</p>
</dd>
</dl>
<p>Example command lines:
</p>
<p>To create a TLS/SSL server that serves an input stream.
</p>
<div class="example">
<pre class="example">ffmpeg -i <var>input</var> -f <var>format</var> tls://<var>hostname</var>:<var>port</var>?listen&cert=<var>server.crt</var>&key=<var>server.key</var>
</pre></div>
<p>To play back a stream from the TLS/SSL server using <code>ffplay</code>:
</p>
<div class="example">
<pre class="example">ffplay tls://<var>hostname</var>:<var>port</var>
</pre></div>
<a name="udp"></a>
<h3 class="section">24.34 udp<span class="pull-right"><a class="anchor hidden-xs" href="#udp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-udp" aria-hidden="true">TOC</a></span></h3>
<p>User Datagram Protocol.
</p>
<p>The required syntax for an UDP URL is:
</p><div class="example">
<pre class="example">udp://<var>hostname</var>:<var>port</var>[?<var>options</var>]
</pre></div>
<p><var>options</var> contains a list of &-separated options of the form <var>key</var>=<var>val</var>.
</p>
<p>In case threading is enabled on the system, a circular buffer is used
to store the incoming data, which allows one to reduce loss of data due to
UDP socket buffer overruns. The <var>fifo_size</var> and
<var>overrun_nonfatal</var> options are related to this buffer.
</p>
<p>The list of supported options follows.
</p>
<dl compact="compact">
<dt><samp>buffer_size=<var>size</var></samp></dt>
<dd><p>Set the UDP maximum socket buffer size in bytes. This is used to set either
the receive or send buffer size, depending on what the socket is used for.
Default is 64KB. See also <var>fifo_size</var>.
</p>
</dd>
<dt><samp>localport=<var>port</var></samp></dt>
<dd><p>Override the local UDP port to bind with.
</p>
</dd>
<dt><samp>localaddr=<var>addr</var></samp></dt>
<dd><p>Choose the local IP address. This is useful e.g. if sending multicast
and the host has multiple interfaces, where the user can choose
which interface to send on by specifying the IP address of that interface.
</p>
</dd>
<dt><samp>pkt_size=<var>size</var></samp></dt>
<dd><p>Set the size in bytes of UDP packets.
</p>
</dd>
<dt><samp>reuse=<var>1|0</var></samp></dt>
<dd><p>Explicitly allow or disallow reusing UDP sockets.
</p>
</dd>
<dt><samp>ttl=<var>ttl</var></samp></dt>
<dd><p>Set the time to live value (for multicast only).
</p>
</dd>
<dt><samp>connect=<var>1|0</var></samp></dt>
<dd><p>Initialize the UDP socket with <code>connect()</code>. In this case, the
destination address can’t be changed with ff_udp_set_remote_url later.
If the destination address isn’t known at the start, this option can
be specified in ff_udp_set_remote_url, too.
This allows finding out the source address for the packets with getsockname,
and makes writes return with AVERROR(ECONNREFUSED) if "destination
unreachable" is received.
For receiving, this gives the benefit of only receiving packets from
the specified peer address/port.
</p>
</dd>
<dt><samp>sources=<var>address</var>[,<var>address</var>]</samp></dt>
<dd><p>Only receive packets sent to the multicast group from one of the
specified sender IP addresses.
</p>
</dd>
<dt><samp>block=<var>address</var>[,<var>address</var>]</samp></dt>
<dd><p>Ignore packets sent to the multicast group from the specified
sender IP addresses.
</p>
</dd>
<dt><samp>fifo_size=<var>units</var></samp></dt>
<dd><p>Set the UDP receiving circular buffer size, expressed as a number of
packets with size of 188 bytes. If not specified defaults to 7*4096.
</p>
</dd>
<dt><samp>overrun_nonfatal=<var>1|0</var></samp></dt>
<dd><p>Survive in case of UDP receiving circular buffer overrun. Default
value is 0.
</p>
</dd>
<dt><samp>timeout=<var>microseconds</var></samp></dt>
<dd><p>Set raise error timeout, expressed in microseconds.
</p>
<p>This option is only relevant in read mode: if no data arrived in more
than this time interval, raise error.
</p>
</dd>
<dt><samp>broadcast=<var>1|0</var></samp></dt>
<dd><p>Explicitly allow or disallow UDP broadcasting.
</p>
<p>Note that broadcasting may not work properly on networks having
a broadcast storm protection.
</p></dd>
</dl>
<a name="Examples-13"></a>
<h4 class="subsection">24.34.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-13" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-13" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use <code>ffmpeg</code> to stream over UDP to a remote endpoint:
<div class="example">
<pre class="example">ffmpeg -i <var>input</var> -f <var>format</var> udp://<var>hostname</var>:<var>port</var>
</pre></div>
</li><li> Use <code>ffmpeg</code> to stream in mpegts format over UDP using 188
sized UDP packets, using a large input buffer:
<div class="example">
<pre class="example">ffmpeg -i <var>input</var> -f mpegts udp://<var>hostname</var>:<var>port</var>?pkt_size=188&buffer_size=65535
</pre></div>
</li><li> Use <code>ffmpeg</code> to receive over UDP from a remote endpoint:
<div class="example">
<pre class="example">ffmpeg -i udp://[<var>multicast-address</var>]:<var>port</var> ...
</pre></div>
</li></ul>
<a name="unix"></a>
<h3 class="section">24.35 unix<span class="pull-right"><a class="anchor hidden-xs" href="#unix" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-unix" aria-hidden="true">TOC</a></span></h3>
<p>Unix local socket
</p>
<p>The required syntax for a Unix socket URL is:
</p>
<div class="example">
<pre class="example">unix://<var>filepath</var>
</pre></div>
<p>The following parameters can be set via command line options
(or in code via <code>AVOption</code>s):
</p>
<dl compact="compact">
<dt><samp>timeout</samp></dt>
<dd><p>Timeout in ms.
</p></dd>
<dt><samp>listen</samp></dt>
<dd><p>Create the Unix socket in listening mode.
</p></dd>
</dl>
<a name="Device-Options"></a>
<h2 class="chapter">25 Device Options<span class="pull-right"><a class="anchor hidden-xs" href="#Device-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Device-Options" aria-hidden="true">TOC</a></span></h2>
<p>The libavdevice library provides the same interface as
libavformat. Namely, an input device is considered like a demuxer, and
an output device like a muxer, and the interface and generic device
options are the same provided by libavformat (see the ffmpeg-formats
manual).
</p>
<p>In addition each input or output device may support so-called private
options, which are specific for that component.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools, or by setting the value explicitly in the device
<code>AVFormatContext</code> options or using the <samp>libavutil/opt.h</samp> API
for programmatic use.
</p>
<a name="Input-Devices"></a>
<h2 class="chapter">26 Input Devices<span class="pull-right"><a class="anchor hidden-xs" href="#Input-Devices" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Input-Devices" aria-hidden="true">TOC</a></span></h2>
<p>Input devices are configured elements in FFmpeg which enable accessing
the data coming from a multimedia device attached to your system.
</p>
<p>When you configure your FFmpeg build, all the supported input devices
are enabled by default. You can list all available ones using the
configure option "–list-indevs".
</p>
<p>You can disable all the input devices using the configure option
"–disable-indevs", and selectively enable an input device using the
option "–enable-indev=<var>INDEV</var>", or you can disable a particular
input device using the option "–disable-indev=<var>INDEV</var>".
</p>
<p>The option "-devices" of the ff* tools will display the list of
supported input devices.
</p>
<p>A description of the currently available input devices follows.
</p>
<a name="alsa"></a>
<h3 class="section">26.1 alsa<span class="pull-right"><a class="anchor hidden-xs" href="#alsa" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-alsa" aria-hidden="true">TOC</a></span></h3>
<p>ALSA (Advanced Linux Sound Architecture) input device.
</p>
<p>To enable this input device during configuration you need libasound
installed on your system.
</p>
<p>This device allows capturing from an ALSA device. The name of the
device to capture has to be an ALSA card identifier.
</p>
<p>An ALSA identifier has the syntax:
</p><div class="example">
<pre class="example">hw:<var>CARD</var>[,<var>DEV</var>[,<var>SUBDEV</var>]]
</pre></div>
<p>where the <var>DEV</var> and <var>SUBDEV</var> components are optional.
</p>
<p>The three arguments (in order: <var>CARD</var>,<var>DEV</var>,<var>SUBDEV</var>)
specify card number or identifier, device number and subdevice number
(-1 means any).
</p>
<p>To see the list of cards currently recognized by your system check the
files <samp>/proc/asound/cards</samp> and <samp>/proc/asound/devices</samp>.
</p>
<p>For example to capture with <code>ffmpeg</code> from an ALSA device with
card id 0, you may run the command:
</p><div class="example">
<pre class="example">ffmpeg -f alsa -i hw:0 alsaout.wav
</pre></div>
<p>For more information see:
<a href="http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html">http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html</a>
</p>
<a name="Options-41"></a>
<h4 class="subsection">26.1.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-41" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-41" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>sample_rate</samp></dt>
<dd><p>Set the sample rate in Hz. Default is 48000.
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels. Default is 2.
</p>
</dd>
</dl>
<a name="avfoundation"></a>
<h3 class="section">26.2 avfoundation<span class="pull-right"><a class="anchor hidden-xs" href="#avfoundation" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-avfoundation" aria-hidden="true">TOC</a></span></h3>
<p>AVFoundation input device.
</p>
<p>AVFoundation is the currently recommended framework by Apple for streamgrabbing on OSX >= 10.7 as well as on iOS.
The older QTKit framework has been marked deprecated since OSX version 10.7.
</p>
<p>The input filename has to be given in the following syntax:
</p><div class="example">
<pre class="example">-i "[[VIDEO]:[AUDIO]]"
</pre></div>
<p>The first entry selects the video input while the latter selects the audio input.
The stream has to be specified by the device name or the device index as shown by the device list.
Alternatively, the video and/or audio input device can be chosen by index using the
<samp>
-video_device_index <INDEX>
</samp>
and/or
<samp>
-audio_device_index <INDEX>
</samp>
, overriding any
device name or index given in the input filename.
</p>
<p>All available devices can be enumerated by using <samp>-list_devices true</samp>, listing
all device names and corresponding indices.
</p>
<p>There are two device name aliases:
</p><dl compact="compact">
<dt><code>default</code></dt>
<dd><p>Select the AVFoundation default device of the corresponding type.
</p>
</dd>
<dt><code>none</code></dt>
<dd><p>Do not record the corresponding media type.
This is equivalent to specifying an empty device name or index.
</p>
</dd>
</dl>
<a name="Options-42"></a>
<h4 class="subsection">26.2.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-42" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-42" aria-hidden="true">TOC</a></span></h4>
<p>AVFoundation supports the following options:
</p>
<dl compact="compact">
<dt><samp>-list_devices <TRUE|FALSE></samp></dt>
<dd><p>If set to true, a list of all available input devices is given showing all
device names and indices.
</p>
</dd>
<dt><samp>-video_device_index <INDEX></samp></dt>
<dd><p>Specify the video device by its index. Overrides anything given in the input filename.
</p>
</dd>
<dt><samp>-audio_device_index <INDEX></samp></dt>
<dd><p>Specify the audio device by its index. Overrides anything given in the input filename.
</p>
</dd>
<dt><samp>-pixel_format <FORMAT></samp></dt>
<dd><p>Request the video device to use a specific pixel format.
If the specified format is not supported, a list of available formats is given
und the first one in this list is used instead. Available pixel formats are:
<code>monob, rgb555be, rgb555le, rgb565be, rgb565le, rgb24, bgr24, 0rgb, bgr0, 0bgr, rgb0,
bgr48be, uyvy422, yuva444p, yuva444p16le, yuv444p, yuv422p16, yuv422p10, yuv444p10,
yuv420p, nv12, yuyv422, gray</code>
</p>
</dd>
<dt><samp>-framerate</samp></dt>
<dd><p>Set the grabbing frame rate. Default is <code>ntsc</code>, corresponding to a
frame rate of <code>30000/1001</code>.
</p>
</dd>
<dt><samp>-video_size</samp></dt>
<dd><p>Set the video frame size.
</p>
</dd>
<dt><samp>-capture_cursor</samp></dt>
<dd><p>Capture the mouse pointer. Default is 0.
</p>
</dd>
<dt><samp>-capture_mouse_clicks</samp></dt>
<dd><p>Capture the screen mouse clicks. Default is 0.
</p>
</dd>
</dl>
<a name="Examples-14"></a>
<h4 class="subsection">26.2.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-14" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-14" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Print the list of AVFoundation supported devices and exit:
<div class="example">
<pre class="example">$ ffmpeg -f avfoundation -list_devices true -i ""
</pre></div>
</li><li> Record video from video device 0 and audio from audio device 0 into out.avi:
<div class="example">
<pre class="example">$ ffmpeg -f avfoundation -i "0:0" out.avi
</pre></div>
</li><li> Record video from video device 2 and audio from audio device 1 into out.avi:
<div class="example">
<pre class="example">$ ffmpeg -f avfoundation -video_device_index 2 -i ":1" out.avi
</pre></div>
</li><li> Record video from the system default video device using the pixel format bgr0 and do not record any audio into out.avi:
<div class="example">
<pre class="example">$ ffmpeg -f avfoundation -pixel_format bgr0 -i "default:none" out.avi
</pre></div>
</li></ul>
<a name="bktr"></a>
<h3 class="section">26.3 bktr<span class="pull-right"><a class="anchor hidden-xs" href="#bktr" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bktr" aria-hidden="true">TOC</a></span></h3>
<p>BSD video input device.
</p>
<a name="Options-43"></a>
<h4 class="subsection">26.3.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-43" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-43" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>framerate</samp></dt>
<dd><p>Set the frame rate.
</p>
</dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the video frame size. Default is <code>vga</code>.
</p>
</dd>
<dt><samp>standard</samp></dt>
<dd>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>pal</samp>’</dt>
<dt>‘<samp>ntsc</samp>’</dt>
<dt>‘<samp>secam</samp>’</dt>
<dt>‘<samp>paln</samp>’</dt>
<dt>‘<samp>palm</samp>’</dt>
<dt>‘<samp>ntscj</samp>’</dt>
</dl>
</dd>
</dl>
<a name="decklink"></a>
<h3 class="section">26.4 decklink<span class="pull-right"><a class="anchor hidden-xs" href="#decklink" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-decklink" aria-hidden="true">TOC</a></span></h3>
<p>The decklink input device provides capture capabilities for Blackmagic
DeckLink devices.
</p>
<p>To enable this input device, you need the Blackmagic DeckLink SDK and you
need to configure with the appropriate <code>--extra-cflags</code>
and <code>--extra-ldflags</code>.
On Windows, you need to run the IDL files through <code>widl</code>.
</p>
<p>DeckLink is very picky about the formats it supports. Pixel format is
uyvy422 or v210, framerate and video size must be determined for your device with
<code>-list_formats 1</code>. Audio sample rate is always 48 kHz and the number
of channels can be 2, 8 or 16.
</p>
<a name="Options-44"></a>
<h4 class="subsection">26.4.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-44" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-44" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>list_devices</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of devices and exit.
Defaults to <samp>false</samp>.
</p>
</dd>
<dt><samp>list_formats</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of supported formats and exit.
Defaults to <samp>false</samp>.
</p>
</dd>
<dt><samp>bm_v210</samp></dt>
<dd><p>If set to ‘<samp>1</samp>’, video is captured in 10 bit v210 instead
of uyvy422. Not all Blackmagic devices support this option.
</p>
</dd>
</dl>
<a name="Examples-15"></a>
<h4 class="subsection">26.4.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-15" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-15" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> List input devices:
<div class="example">
<pre class="example">ffmpeg -f decklink -list_devices 1 -i dummy
</pre></div>
</li><li> List supported formats:
<div class="example">
<pre class="example">ffmpeg -f decklink -list_formats 1 -i 'Intensity Pro'
</pre></div>
</li><li> Capture video clip at 1080i50 (format 11):
<div class="example">
<pre class="example">ffmpeg -f decklink -i 'Intensity Pro@11' -acodec copy -vcodec copy output.avi
</pre></div>
</li><li> Capture video clip at 1080i50 10 bit:
<div class="example">
<pre class="example">ffmpeg -bm_v210 1 -f decklink -i 'UltraStudio Mini Recorder@11' -acodec copy -vcodec copy output.avi
</pre></div>
</li></ul>
<a name="dshow"></a>
<h3 class="section">26.5 dshow<span class="pull-right"><a class="anchor hidden-xs" href="#dshow" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dshow" aria-hidden="true">TOC</a></span></h3>
<p>Windows DirectShow input device.
</p>
<p>DirectShow support is enabled when FFmpeg is built with the mingw-w64 project.
Currently only audio and video devices are supported.
</p>
<p>Multiple devices may be opened as separate inputs, but they may also be
opened on the same input, which should improve synchronism between them.
</p>
<p>The input name should be in the format:
</p>
<div class="example">
<pre class="example"><var>TYPE</var>=<var>NAME</var>[:<var>TYPE</var>=<var>NAME</var>]
</pre></div>
<p>where <var>TYPE</var> can be either <var>audio</var> or <var>video</var>,
and <var>NAME</var> is the device’s name or alternative name..
</p>
<a name="Options-45"></a>
<h4 class="subsection">26.5.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-45" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-45" aria-hidden="true">TOC</a></span></h4>
<p>If no options are specified, the device’s defaults are used.
If the device does not support the requested options, it will
fail to open.
</p>
<dl compact="compact">
<dt><samp>video_size</samp></dt>
<dd><p>Set the video size in the captured video.
</p>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>Set the frame rate in the captured video.
</p>
</dd>
<dt><samp>sample_rate</samp></dt>
<dd><p>Set the sample rate (in Hz) of the captured audio.
</p>
</dd>
<dt><samp>sample_size</samp></dt>
<dd><p>Set the sample size (in bits) of the captured audio.
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels in the captured audio.
</p>
</dd>
<dt><samp>list_devices</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of devices and exit.
</p>
</dd>
<dt><samp>list_options</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of selected device’s options
and exit.
</p>
</dd>
<dt><samp>video_device_number</samp></dt>
<dd><p>Set video device number for devices with the same name (starts at 0,
defaults to 0).
</p>
</dd>
<dt><samp>audio_device_number</samp></dt>
<dd><p>Set audio device number for devices with the same name (starts at 0,
defaults to 0).
</p>
</dd>
<dt><samp>pixel_format</samp></dt>
<dd><p>Select pixel format to be used by DirectShow. This may only be set when
the video codec is not set or set to rawvideo.
</p>
</dd>
<dt><samp>audio_buffer_size</samp></dt>
<dd><p>Set audio device buffer size in milliseconds (which can directly
impact latency, depending on the device).
Defaults to using the audio device’s
default buffer size (typically some multiple of 500ms).
Setting this value too low can degrade performance.
See also
<a href="http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx">http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx</a>
</p>
</dd>
<dt><samp>video_pin_name</samp></dt>
<dd><p>Select video capture pin to use by name or alternative name.
</p>
</dd>
<dt><samp>audio_pin_name</samp></dt>
<dd><p>Select audio capture pin to use by name or alternative name.
</p>
</dd>
<dt><samp>crossbar_video_input_pin_number</samp></dt>
<dd><p>Select video input pin number for crossbar device. This will be
routed to the crossbar device’s Video Decoder output pin.
Note that changing this value can affect future invocations
(sets a new default) until system reboot occurs.
</p>
</dd>
<dt><samp>crossbar_audio_input_pin_number</samp></dt>
<dd><p>Select audio input pin number for crossbar device. This will be
routed to the crossbar device’s Audio Decoder output pin.
Note that changing this value can affect future invocations
(sets a new default) until system reboot occurs.
</p>
</dd>
<dt><samp>show_video_device_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display dialog
to the end user, allowing them to change video filter properties
and configurations manually.
Note that for crossbar devices, adjusting values in this dialog
may be needed at times to toggle between PAL (25 fps) and NTSC (29.97)
input frame rates, sizes, interlacing, etc. Changing these values can
enable different scan rates/frame rates and avoiding green bars at
the bottom, flickering scan lines, etc.
Note that with some devices, changing these properties can also affect future
invocations (sets new defaults) until system reboot occurs.
</p>
</dd>
<dt><samp>show_audio_device_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display dialog
to the end user, allowing them to change audio filter properties
and configurations manually.
</p>
</dd>
<dt><samp>show_video_crossbar_connection_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify crossbar pin routings, when it opens a video device.
</p>
</dd>
<dt><samp>show_audio_crossbar_connection_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify crossbar pin routings, when it opens an audio device.
</p>
</dd>
<dt><samp>show_analog_tv_tuner_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify TV channels and frequencies.
</p>
</dd>
<dt><samp>show_analog_tv_tuner_audio_dialog</samp></dt>
<dd><p>If set to <samp>true</samp>, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify TV audio (like mono vs. stereo, Language A,B or C).
</p>
</dd>
<dt><samp>audio_device_load</samp></dt>
<dd><p>Load an audio capture filter device from file instead of searching
it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to.
To use this an audio capture source has to be specified, but it can
be anything even fake one.
</p>
</dd>
<dt><samp>audio_device_save</samp></dt>
<dd><p>Save the currently used audio capture filter device and its
parameters (if the filter supports it) to a file.
If a file with the same name exists it will be overwritten.
</p>
</dd>
<dt><samp>video_device_load</samp></dt>
<dd><p>Load a video capture filter device from file instead of searching
it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to.
To use this a video capture source has to be specified, but it can
be anything even fake one.
</p>
</dd>
<dt><samp>video_device_save</samp></dt>
<dd><p>Save the currently used video capture filter device and its
parameters (if the filter supports it) to a file.
If a file with the same name exists it will be overwritten.
</p>
</dd>
</dl>
<a name="Examples-16"></a>
<h4 class="subsection">26.5.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-16" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-16" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Print the list of DirectShow supported devices and exit:
<div class="example">
<pre class="example">$ ffmpeg -list_devices true -f dshow -i dummy
</pre></div>
</li><li> Open video device <var>Camera</var>:
<div class="example">
<pre class="example">$ ffmpeg -f dshow -i video="Camera"
</pre></div>
</li><li> Open second video device with name <var>Camera</var>:
<div class="example">
<pre class="example">$ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
</pre></div>
</li><li> Open video device <var>Camera</var> and audio device <var>Microphone</var>:
<div class="example">
<pre class="example">$ ffmpeg -f dshow -i video="Camera":audio="Microphone"
</pre></div>
</li><li> Print the list of supported options in selected device and exit:
<div class="example">
<pre class="example">$ ffmpeg -list_options true -f dshow -i video="Camera"
</pre></div>
</li><li> Specify pin names to capture by name or alternative name, specify alternative device name:
<div class="example">
<pre class="example">$ ffmpeg -f dshow -audio_pin_name "Audio Out" -video_pin_name 2 -i video=video="@device_pnp_\\?\pci#ven_1a0a&dev_6200&subsys_62021461&rev_01#4&e2c7dd6&0&00e1#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\{ca465100-deb0-4d59-818f-8c477184adf6}":audio="Microphone"
</pre></div>
</li><li> Configure a crossbar device, specifying crossbar pins, allow user to adjust video capture properties at startup:
<div class="example">
<pre class="example">$ ffmpeg -f dshow -show_video_device_dialog true -crossbar_video_input_pin_number 0
-crossbar_audio_input_pin_number 3 -i video="AVerMedia BDA Analog Capture":audio="AVerMedia BDA Analog Capture"
</pre></div>
</li></ul>
<a name="dv1394"></a>
<h3 class="section">26.6 dv1394<span class="pull-right"><a class="anchor hidden-xs" href="#dv1394" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dv1394" aria-hidden="true">TOC</a></span></h3>
<p>Linux DV 1394 input device.
</p>
<a name="Options-46"></a>
<h4 class="subsection">26.6.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-46" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-46" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>framerate</samp></dt>
<dd><p>Set the frame rate. Default is 25.
</p>
</dd>
<dt><samp>standard</samp></dt>
<dd>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>pal</samp>’</dt>
<dt>‘<samp>ntsc</samp>’</dt>
</dl>
<p>Default value is <code>ntsc</code>.
</p>
</dd>
</dl>
<a name="fbdev"></a>
<h3 class="section">26.7 fbdev<span class="pull-right"><a class="anchor hidden-xs" href="#fbdev" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fbdev" aria-hidden="true">TOC</a></span></h3>
<p>Linux framebuffer input device.
</p>
<p>The Linux framebuffer is a graphic hardware-independent abstraction
layer to show graphics on a computer monitor, typically on the
console. It is accessed through a file device node, usually
<samp>/dev/fb0</samp>.
</p>
<p>For more detailed information read the file
Documentation/fb/framebuffer.txt included in the Linux source tree.
</p>
<p>See also <a href="http://linux-fbdev.sourceforge.net/">http://linux-fbdev.sourceforge.net/</a>, and fbset(1).
</p>
<p>To record from the framebuffer device <samp>/dev/fb0</samp> with
<code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -f fbdev -framerate 10 -i /dev/fb0 out.avi
</pre></div>
<p>You can take a single screenshot image with the command:
</p><div class="example">
<pre class="example">ffmpeg -f fbdev -framerate 1 -i /dev/fb0 -frames:v 1 screenshot.jpeg
</pre></div>
<a name="Options-47"></a>
<h4 class="subsection">26.7.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-47" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-47" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>framerate</samp></dt>
<dd><p>Set the frame rate. Default is 25.
</p>
</dd>
</dl>
<a name="gdigrab"></a>
<h3 class="section">26.8 gdigrab<span class="pull-right"><a class="anchor hidden-xs" href="#gdigrab" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-gdigrab" aria-hidden="true">TOC</a></span></h3>
<p>Win32 GDI-based screen capture device.
</p>
<p>This device allows you to capture a region of the display on Windows.
</p>
<p>There are two options for the input filename:
</p><div class="example">
<pre class="example">desktop
</pre></div>
<p>or
</p><div class="example">
<pre class="example">title=<var>window_title</var>
</pre></div>
<p>The first option will capture the entire desktop, or a fixed region of the
desktop. The second option will instead capture the contents of a single
window, regardless of its position on the screen.
</p>
<p>For example, to grab the entire desktop using <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -f gdigrab -framerate 6 -i desktop out.mpg
</pre></div>
<p>Grab a 640x480 region at position <code>10,20</code>:
</p><div class="example">
<pre class="example">ffmpeg -f gdigrab -framerate 6 -offset_x 10 -offset_y 20 -video_size vga -i desktop out.mpg
</pre></div>
<p>Grab the contents of the window named "Calculator"
</p><div class="example">
<pre class="example">ffmpeg -f gdigrab -framerate 6 -i title=Calculator out.mpg
</pre></div>
<a name="Options-48"></a>
<h4 class="subsection">26.8.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-48" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-48" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>draw_mouse</samp></dt>
<dd><p>Specify whether to draw the mouse pointer. Use the value <code>0</code> to
not draw the pointer. Default value is <code>1</code>.
</p>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>Set the grabbing frame rate. Default value is <code>ntsc</code>,
corresponding to a frame rate of <code>30000/1001</code>.
</p>
</dd>
<dt><samp>show_region</samp></dt>
<dd><p>Show grabbed region on screen.
</p>
<p>If <var>show_region</var> is specified with <code>1</code>, then the grabbing
region will be indicated on screen. With this option, it is easy to
know what is being grabbed if only a portion of the screen is grabbed.
</p>
<p>Note that <var>show_region</var> is incompatible with grabbing the contents
of a single window.
</p>
<p>For example:
</p><div class="example">
<pre class="example">ffmpeg -f gdigrab -show_region 1 -framerate 6 -video_size cif -offset_x 10 -offset_y 20 -i desktop out.mpg
</pre></div>
</dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the video frame size. The default is to capture the full screen if <samp>desktop</samp> is selected, or the full window size if <samp>title=<var>window_title</var></samp> is selected.
</p>
</dd>
<dt><samp>offset_x</samp></dt>
<dd><p>When capturing a region with <var>video_size</var>, set the distance from the left edge of the screen or desktop.
</p>
<p>Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned to the left of your primary monitor, you will need to use a negative <var>offset_x</var> value to move the region to that monitor.
</p>
</dd>
<dt><samp>offset_y</samp></dt>
<dd><p>When capturing a region with <var>video_size</var>, set the distance from the top edge of the screen or desktop.
</p>
<p>Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned above your primary monitor, you will need to use a negative <var>offset_y</var> value to move the region to that monitor.
</p>
</dd>
</dl>
<a name="iec61883"></a>
<h3 class="section">26.9 iec61883<span class="pull-right"><a class="anchor hidden-xs" href="#iec61883" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-iec61883" aria-hidden="true">TOC</a></span></h3>
<p>FireWire DV/HDV input device using libiec61883.
</p>
<p>To enable this input device, you need libiec61883, libraw1394 and
libavc1394 installed on your system. Use the configure option
<code>--enable-libiec61883</code> to compile with the device enabled.
</p>
<p>The iec61883 capture device supports capturing from a video device
connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
FireWire stack (juju). This is the default DV/HDV input method in Linux
Kernel 2.6.37 and later, since the old FireWire stack was removed.
</p>
<p>Specify the FireWire port to be used as input file, or "auto"
to choose the first port connected.
</p>
<a name="Options-49"></a>
<h4 class="subsection">26.9.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-49" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-49" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>dvtype</samp></dt>
<dd><p>Override autodetection of DV/HDV. This should only be used if auto
detection does not work, or if usage of a different device type
should be prohibited. Treating a DV device as HDV (or vice versa) will
not work and result in undefined behavior.
The values <samp>auto</samp>, <samp>dv</samp> and <samp>hdv</samp> are supported.
</p>
</dd>
<dt><samp>dvbuffer</samp></dt>
<dd><p>Set maximum size of buffer for incoming data, in frames. For DV, this
is an exact value. For HDV, it is not frame exact, since HDV does
not have a fixed frame size.
</p>
</dd>
<dt><samp>dvguid</samp></dt>
<dd><p>Select the capture device by specifying it’s GUID. Capturing will only
be performed from the specified device and fails if no device with the
given GUID is found. This is useful to select the input if multiple
devices are connected at the same time.
Look at /sys/bus/firewire/devices to find out the GUIDs.
</p>
</dd>
</dl>
<a name="Examples-17"></a>
<h4 class="subsection">26.9.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-17" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-17" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Grab and show the input of a FireWire DV/HDV device.
<div class="example">
<pre class="example">ffplay -f iec61883 -i auto
</pre></div>
</li><li> Grab and record the input of a FireWire DV/HDV device,
using a packet buffer of 100000 packets if the source is HDV.
<div class="example">
<pre class="example">ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg
</pre></div>
</li></ul>
<a name="jack"></a>
<h3 class="section">26.10 jack<span class="pull-right"><a class="anchor hidden-xs" href="#jack" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-jack" aria-hidden="true">TOC</a></span></h3>
<p>JACK input device.
</p>
<p>To enable this input device during configuration you need libjack
installed on your system.
</p>
<p>A JACK input device creates one or more JACK writable clients, one for
each audio channel, with name <var>client_name</var>:input_<var>N</var>, where
<var>client_name</var> is the name provided by the application, and <var>N</var>
is a number which identifies the channel.
Each writable client will send the acquired data to the FFmpeg input
device.
</p>
<p>Once you have created one or more JACK readable clients, you need to
connect them to one or more JACK writable clients.
</p>
<p>To connect or disconnect JACK clients you can use the <code>jack_connect</code>
and <code>jack_disconnect</code> programs, or do it through a graphical interface,
for example with <code>qjackctl</code>.
</p>
<p>To list the JACK clients and their properties you can invoke the command
<code>jack_lsp</code>.
</p>
<p>Follows an example which shows how to capture a JACK readable client
with <code>ffmpeg</code>.
</p><div class="example">
<pre class="example"># Create a JACK writable client with name "ffmpeg".
$ ffmpeg -f jack -i ffmpeg -y out.wav
# Start the sample jack_metro readable client.
$ jack_metro -b 120 -d 0.2 -f 4000
# List the current JACK clients.
$ jack_lsp -c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
ffmpeg:input_1
metro:120_bpm
# Connect metro to the ffmpeg writable client.
$ jack_connect metro:120_bpm ffmpeg:input_1
</pre></div>
<p>For more information read:
<a href="http://jackaudio.org/">http://jackaudio.org/</a>
</p>
<a name="Options-50"></a>
<h4 class="subsection">26.10.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-50" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-50" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels. Default is 2.
</p>
</dd>
</dl>
<a name="lavfi"></a>
<h3 class="section">26.11 lavfi<span class="pull-right"><a class="anchor hidden-xs" href="#lavfi" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-lavfi" aria-hidden="true">TOC</a></span></h3>
<p>Libavfilter input virtual device.
</p>
<p>This input device reads data from the open output pads of a libavfilter
filtergraph.
</p>
<p>For each filtergraph open output, the input device will create a
corresponding stream which is mapped to the generated output. Currently
only video data is supported. The filtergraph is specified through the
option <samp>graph</samp>.
</p>
<a name="Options-51"></a>
<h4 class="subsection">26.11.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-51" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-51" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>graph</samp></dt>
<dd><p>Specify the filtergraph to use as input. Each video open output must be
labelled by a unique string of the form "out<var>N</var>", where <var>N</var> is a
number starting from 0 corresponding to the mapped input stream
generated by the device.
The first unlabelled output is automatically assigned to the "out0"
label, but all the others need to be specified explicitly.
</p>
<p>The suffix "+subcc" can be appended to the output label to create an extra
stream with the closed captions packets attached to that output
(experimental; only for EIA-608 / CEA-708 for now).
The subcc streams are created after all the normal streams, in the order of
the corresponding stream.
For example, if there is "out19+subcc", "out7+subcc" and up to "out42", the
stream #43 is subcc for stream #7 and stream #44 is subcc for stream #19.
</p>
<p>If not specified defaults to the filename specified for the input
device.
</p>
</dd>
<dt><samp>graph_file</samp></dt>
<dd><p>Set the filename of the filtergraph to be read and sent to the other
filters. Syntax of the filtergraph is the same as the one specified by
the option <var>graph</var>.
</p>
</dd>
<dt><samp>dumpgraph</samp></dt>
<dd><p>Dump graph to stderr.
</p>
</dd>
</dl>
<a name="Examples-18"></a>
<h4 class="subsection">26.11.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-18" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-18" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Create a color video stream and play it back with <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi -graph "color=c=pink [out0]" dummy
</pre></div>
</li><li> As the previous example, but use filename for specifying the graph
description, and omit the "out0" label:
<div class="example">
<pre class="example">ffplay -f lavfi color=c=pink
</pre></div>
</li><li> Create three different video test filtered sources and play them:
<div class="example">
<pre class="example">ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
</pre></div>
</li><li> Read an audio stream from a file using the amovie source and play it
back with <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi "amovie=test.wav"
</pre></div>
</li><li> Read an audio stream and a video stream and play it back with
<code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
</pre></div>
</li><li> Dump decoded frames to images and closed captions to a file (experimental):
<div class="example">
<pre class="example">ffmpeg -f lavfi -i "movie=test.ts[out0+subcc]" -map v frame%08d.png -map s -c copy -f rawvideo subcc.bin
</pre></div>
</li></ul>
<a name="libcdio"></a>
<h3 class="section">26.12 libcdio<span class="pull-right"><a class="anchor hidden-xs" href="#libcdio" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libcdio" aria-hidden="true">TOC</a></span></h3>
<p>Audio-CD input device based on libcdio.
</p>
<p>To enable this input device during configuration you need libcdio
installed on your system. It requires the configure option
<code>--enable-libcdio</code>.
</p>
<p>This device allows playing and grabbing from an Audio-CD.
</p>
<p>For example to copy with <code>ffmpeg</code> the entire Audio-CD in <samp>/dev/sr0</samp>,
you may run the command:
</p><div class="example">
<pre class="example">ffmpeg -f libcdio -i /dev/sr0 cd.wav
</pre></div>
<a name="Options-52"></a>
<h4 class="subsection">26.12.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-52" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-52" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>speed</samp></dt>
<dd><p>Set drive reading speed. Default value is 0.
</p>
<p>The speed is specified CD-ROM speed units. The speed is set through
the libcdio <code>cdio_cddap_speed_set</code> function. On many CD-ROM
drives, specifying a value too large will result in using the fastest
speed.
</p>
</dd>
<dt><samp>paranoia_mode</samp></dt>
<dd><p>Set paranoia recovery mode flags. It accepts one of the following values:
</p>
<dl compact="compact">
<dt>‘<samp>disable</samp>’</dt>
<dt>‘<samp>verify</samp>’</dt>
<dt>‘<samp>overlap</samp>’</dt>
<dt>‘<samp>neverskip</samp>’</dt>
<dt>‘<samp>full</samp>’</dt>
</dl>
<p>Default value is ‘<samp>disable</samp>’.
</p>
<p>For more information about the available recovery modes, consult the
paranoia project documentation.
</p></dd>
</dl>
<a name="libdc1394"></a>
<h3 class="section">26.13 libdc1394<span class="pull-right"><a class="anchor hidden-xs" href="#libdc1394" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-libdc1394" aria-hidden="true">TOC</a></span></h3>
<p>IIDC1394 input device, based on libdc1394 and libraw1394.
</p>
<p>Requires the configure option <code>--enable-libdc1394</code>.
</p>
<a name="openal"></a>
<h3 class="section">26.14 openal<span class="pull-right"><a class="anchor hidden-xs" href="#openal" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-openal" aria-hidden="true">TOC</a></span></h3>
<p>The OpenAL input device provides audio capture on all systems with a
working OpenAL 1.1 implementation.
</p>
<p>To enable this input device during configuration, you need OpenAL
headers and libraries installed on your system, and need to configure
FFmpeg with <code>--enable-openal</code>.
</p>
<p>OpenAL headers and libraries should be provided as part of your OpenAL
implementation, or as an additional download (an SDK). Depending on your
installation you may need to specify additional flags via the
<code>--extra-cflags</code> and <code>--extra-ldflags</code> for allowing the build
system to locate the OpenAL headers and libraries.
</p>
<p>An incomplete list of OpenAL implementations follows:
</p>
<dl compact="compact">
<dt><strong>Creative</strong></dt>
<dd><p>The official Windows implementation, providing hardware acceleration
with supported devices and software fallback.
See <a href="http://openal.org/">http://openal.org/</a>.
</p></dd>
<dt><strong>OpenAL Soft</strong></dt>
<dd><p>Portable, open source (LGPL) software implementation. Includes
backends for the most common sound APIs on the Windows, Linux,
Solaris, and BSD operating systems.
See <a href="http://kcat.strangesoft.net/openal.html">http://kcat.strangesoft.net/openal.html</a>.
</p></dd>
<dt><strong>Apple</strong></dt>
<dd><p>OpenAL is part of Core Audio, the official Mac OS X Audio interface.
See <a href="http://developer.apple.com/technologies/mac/audio-and-video.html">http://developer.apple.com/technologies/mac/audio-and-video.html</a>
</p></dd>
</dl>
<p>This device allows one to capture from an audio input device handled
through OpenAL.
</p>
<p>You need to specify the name of the device to capture in the provided
filename. If the empty string is provided, the device will
automatically select the default device. You can get the list of the
supported devices by using the option <var>list_devices</var>.
</p>
<a name="Options-53"></a>
<h4 class="subsection">26.14.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-53" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-53" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels in the captured audio. Only the values
<samp>1</samp> (monaural) and <samp>2</samp> (stereo) are currently supported.
Defaults to <samp>2</samp>.
</p>
</dd>
<dt><samp>sample_size</samp></dt>
<dd><p>Set the sample size (in bits) of the captured audio. Only the values
<samp>8</samp> and <samp>16</samp> are currently supported. Defaults to
<samp>16</samp>.
</p>
</dd>
<dt><samp>sample_rate</samp></dt>
<dd><p>Set the sample rate (in Hz) of the captured audio.
Defaults to <samp>44.1k</samp>.
</p>
</dd>
<dt><samp>list_devices</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of devices and exit.
Defaults to <samp>false</samp>.
</p>
</dd>
</dl>
<a name="Examples-19"></a>
<h4 class="subsection">26.14.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-19" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-19" aria-hidden="true">TOC</a></span></h4>
<p>Print the list of OpenAL supported devices and exit:
</p><div class="example">
<pre class="example">$ ffmpeg -list_devices true -f openal -i dummy out.ogg
</pre></div>
<p>Capture from the OpenAL device <samp>DR-BT101 via PulseAudio</samp>:
</p><div class="example">
<pre class="example">$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
</pre></div>
<p>Capture from the default device (note the empty string ” as filename):
</p><div class="example">
<pre class="example">$ ffmpeg -f openal -i '' out.ogg
</pre></div>
<p>Capture from two devices simultaneously, writing to two different files,
within the same <code>ffmpeg</code> command:
</p><div class="example">
<pre class="example">$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
</pre></div>
<p>Note: not all OpenAL implementations support multiple simultaneous capture -
try the latest OpenAL Soft if the above does not work.
</p>
<a name="oss"></a>
<h3 class="section">26.15 oss<span class="pull-right"><a class="anchor hidden-xs" href="#oss" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-oss" aria-hidden="true">TOC</a></span></h3>
<p>Open Sound System input device.
</p>
<p>The filename to provide to the input device is the device node
representing the OSS input device, and is usually set to
<samp>/dev/dsp</samp>.
</p>
<p>For example to grab from <samp>/dev/dsp</samp> using <code>ffmpeg</code> use the
command:
</p><div class="example">
<pre class="example">ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
</pre></div>
<p>For more information about OSS see:
<a href="http://manuals.opensound.com/usersguide/dsp.html">http://manuals.opensound.com/usersguide/dsp.html</a>
</p>
<a name="Options-54"></a>
<h4 class="subsection">26.15.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-54" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-54" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>sample_rate</samp></dt>
<dd><p>Set the sample rate in Hz. Default is 48000.
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels. Default is 2.
</p>
</dd>
</dl>
<a name="pulse"></a>
<h3 class="section">26.16 pulse<span class="pull-right"><a class="anchor hidden-xs" href="#pulse" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pulse" aria-hidden="true">TOC</a></span></h3>
<p>PulseAudio input device.
</p>
<p>To enable this output device you need to configure FFmpeg with <code>--enable-libpulse</code>.
</p>
<p>The filename to provide to the input device is a source device or the
string "default"
</p>
<p>To list the PulseAudio source devices and their properties you can invoke
the command <code>pactl list sources</code>.
</p>
<p>More information about PulseAudio can be found on <a href="http://www.pulseaudio.org">http://www.pulseaudio.org</a>.
</p>
<a name="Options-55"></a>
<h4 class="subsection">26.16.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-55" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-55" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>server</samp></dt>
<dd><p>Connect to a specific PulseAudio server, specified by an IP address.
Default server is used when not provided.
</p>
</dd>
<dt><samp>name</samp></dt>
<dd><p>Specify the application name PulseAudio will use when showing active clients,
by default it is the <code>LIBAVFORMAT_IDENT</code> string.
</p>
</dd>
<dt><samp>stream_name</samp></dt>
<dd><p>Specify the stream name PulseAudio will use when showing active streams,
by default it is "record".
</p>
</dd>
<dt><samp>sample_rate</samp></dt>
<dd><p>Specify the samplerate in Hz, by default 48kHz is used.
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Specify the channels in use, by default 2 (stereo) is set.
</p>
</dd>
<dt><samp>frame_size</samp></dt>
<dd><p>Specify the number of bytes per frame, by default it is set to 1024.
</p>
</dd>
<dt><samp>fragment_size</samp></dt>
<dd><p>Specify the minimal buffering fragment in PulseAudio, it will affect the
audio latency. By default it is unset.
</p>
</dd>
<dt><samp>wallclock</samp></dt>
<dd><p>Set the initial PTS using the current time. Default is 1.
</p>
</dd>
</dl>
<a name="Examples-20"></a>
<h4 class="subsection">26.16.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-20" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-20" aria-hidden="true">TOC</a></span></h4>
<p>Record a stream from default device:
</p><div class="example">
<pre class="example">ffmpeg -f pulse -i default /tmp/pulse.wav
</pre></div>
<a name="qtkit"></a>
<h3 class="section">26.17 qtkit<span class="pull-right"><a class="anchor hidden-xs" href="#qtkit" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-qtkit" aria-hidden="true">TOC</a></span></h3>
<p>QTKit input device.
</p>
<p>The filename passed as input is parsed to contain either a device name or index.
The device index can also be given by using -video_device_index.
A given device index will override any given device name.
If the desired device consists of numbers only, use -video_device_index to identify it.
The default device will be chosen if an empty string or the device name "default" is given.
The available devices can be enumerated by using -list_devices.
</p>
<div class="example">
<pre class="example">ffmpeg -f qtkit -i "0" out.mpg
</pre></div>
<div class="example">
<pre class="example">ffmpeg -f qtkit -video_device_index 0 -i "" out.mpg
</pre></div>
<div class="example">
<pre class="example">ffmpeg -f qtkit -i "default" out.mpg
</pre></div>
<div class="example">
<pre class="example">ffmpeg -f qtkit -list_devices true -i ""
</pre></div>
<a name="Options-56"></a>
<h4 class="subsection">26.17.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-56" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-56" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>frame_rate</samp></dt>
<dd><p>Set frame rate. Default is 30.
</p>
</dd>
<dt><samp>list_devices</samp></dt>
<dd><p>If set to <code>true</code>, print a list of devices and exit. Default is
<code>false</code>.
</p>
</dd>
<dt><samp>video_device_index</samp></dt>
<dd><p>Select the video device by index for devices with the same name (starts at 0).
</p>
</dd>
</dl>
<a name="sndio"></a>
<h3 class="section">26.18 sndio<span class="pull-right"><a class="anchor hidden-xs" href="#sndio" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sndio" aria-hidden="true">TOC</a></span></h3>
<p>sndio input device.
</p>
<p>To enable this input device during configuration you need libsndio
installed on your system.
</p>
<p>The filename to provide to the input device is the device node
representing the sndio input device, and is usually set to
<samp>/dev/audio0</samp>.
</p>
<p>For example to grab from <samp>/dev/audio0</samp> using <code>ffmpeg</code> use the
command:
</p><div class="example">
<pre class="example">ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
</pre></div>
<a name="Options-57"></a>
<h4 class="subsection">26.18.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-57" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-57" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>sample_rate</samp></dt>
<dd><p>Set the sample rate in Hz. Default is 48000.
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>Set the number of channels. Default is 2.
</p>
</dd>
</dl>
<a name="video4linux2_002c-v4l2"></a>
<h3 class="section">26.19 video4linux2, v4l2<span class="pull-right"><a class="anchor hidden-xs" href="#video4linux2_002c-v4l2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-video4linux2_002c-v4l2" aria-hidden="true">TOC</a></span></h3>
<p>Video4Linux2 input video device.
</p>
<p>"v4l2" can be used as alias for "video4linux2".
</p>
<p>If FFmpeg is built with v4l-utils support (by using the
<code>--enable-libv4l2</code> configure option), it is possible to use it with the
<code>-use_libv4l2</code> input device option.
</p>
<p>The name of the device to grab is a file device node, usually Linux
systems tend to automatically create such nodes when the device
(e.g. an USB webcam) is plugged into the system, and has a name of the
kind <samp>/dev/video<var>N</var></samp>, where <var>N</var> is a number associated to
the device.
</p>
<p>Video4Linux2 devices usually support a limited set of
<var>width</var>x<var>height</var> sizes and frame rates. You can check which are
supported using <code>-list_formats all</code> for Video4Linux2 devices.
Some devices, like TV cards, support one or more standards. It is possible
to list all the supported standards using <code>-list_standards all</code>.
</p>
<p>The time base for the timestamps is 1 microsecond. Depending on the kernel
version and configuration, the timestamps may be derived from the real time
clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
boot time, unaffected by NTP or manual changes to the clock). The
<samp>-timestamps abs</samp> or <samp>-ts abs</samp> option can be used to force
conversion into the real time clock.
</p>
<p>Some usage examples of the video4linux2 device with <code>ffmpeg</code>
and <code>ffplay</code>:
</p><ul>
<li> List supported formats for a video4linux2 device:
<div class="example">
<pre class="example">ffplay -f video4linux2 -list_formats all /dev/video0
</pre></div>
</li><li> Grab and show the input of a video4linux2 device:
<div class="example">
<pre class="example">ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
</pre></div>
</li><li> Grab and record the input of a video4linux2 device, leave the
frame rate and size as previously set:
<div class="example">
<pre class="example">ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
</pre></div>
</li></ul>
<p>For more information about Video4Linux, check <a href="http://linuxtv.org/">http://linuxtv.org/</a>.
</p>
<a name="Options-58"></a>
<h4 class="subsection">26.19.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-58" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-58" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>standard</samp></dt>
<dd><p>Set the standard. Must be the name of a supported standard. To get a
list of the supported standards, use the <samp>list_standards</samp>
option.
</p>
</dd>
<dt><samp>channel</samp></dt>
<dd><p>Set the input channel number. Default to -1, which means using the
previously selected channel.
</p>
</dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the video frame size. The argument must be a string in the form
<var>WIDTH</var>x<var>HEIGHT</var> or a valid size abbreviation.
</p>
</dd>
<dt><samp>pixel_format</samp></dt>
<dd><p>Select the pixel format (only valid for raw video input).
</p>
</dd>
<dt><samp>input_format</samp></dt>
<dd><p>Set the preferred pixel format (for raw video) or a codec name.
This option allows one to select the input format, when several are
available.
</p>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>Set the preferred video frame rate.
</p>
</dd>
<dt><samp>list_formats</samp></dt>
<dd><p>List available formats (supported pixel formats, codecs, and frame
sizes) and exit.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>all</samp>’</dt>
<dd><p>Show all available (compressed and non-compressed) formats.
</p>
</dd>
<dt>‘<samp>raw</samp>’</dt>
<dd><p>Show only raw video (non-compressed) formats.
</p>
</dd>
<dt>‘<samp>compressed</samp>’</dt>
<dd><p>Show only compressed formats.
</p></dd>
</dl>
</dd>
<dt><samp>list_standards</samp></dt>
<dd><p>List supported standards and exit.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>all</samp>’</dt>
<dd><p>Show all supported standards.
</p></dd>
</dl>
</dd>
<dt><samp>timestamps, ts</samp></dt>
<dd><p>Set type of timestamps for grabbed frames.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>default</samp>’</dt>
<dd><p>Use timestamps from the kernel.
</p>
</dd>
<dt>‘<samp>abs</samp>’</dt>
<dd><p>Use absolute timestamps (wall clock).
</p>
</dd>
<dt>‘<samp>mono2abs</samp>’</dt>
<dd><p>Force conversion from monotonic to absolute timestamps.
</p></dd>
</dl>
<p>Default value is <code>default</code>.
</p>
</dd>
<dt><samp>use_libv4l2</samp></dt>
<dd><p>Use libv4l2 (v4l-utils) conversion functions. Default is 0.
</p>
</dd>
</dl>
<a name="vfwcap"></a>
<h3 class="section">26.20 vfwcap<span class="pull-right"><a class="anchor hidden-xs" href="#vfwcap" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vfwcap" aria-hidden="true">TOC</a></span></h3>
<p>VfW (Video for Windows) capture input device.
</p>
<p>The filename passed as input is the capture driver number, ranging from
0 to 9. You may use "list" as filename to print a list of drivers. Any
other filename will be interpreted as device number 0.
</p>
<a name="Options-59"></a>
<h4 class="subsection">26.20.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-59" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-59" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>video_size</samp></dt>
<dd><p>Set the video frame size.
</p>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>Set the grabbing frame rate. Default value is <code>ntsc</code>,
corresponding to a frame rate of <code>30000/1001</code>.
</p>
</dd>
</dl>
<a name="x11grab"></a>
<h3 class="section">26.21 x11grab<span class="pull-right"><a class="anchor hidden-xs" href="#x11grab" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-x11grab" aria-hidden="true">TOC</a></span></h3>
<p>X11 video input device.
</p>
<p>To enable this input device during configuration you need libxcb
installed on your system. It will be automatically detected during
configuration.
</p>
<p>Alternatively, the configure option <samp>--enable-x11grab</samp> exists
for legacy Xlib users.
</p>
<p>This device allows one to capture a region of an X11 display.
</p>
<p>The filename passed as input has the syntax:
</p><div class="example">
<pre class="example">[<var>hostname</var>]:<var>display_number</var>.<var>screen_number</var>[+<var>x_offset</var>,<var>y_offset</var>]
</pre></div>
<p><var>hostname</var>:<var>display_number</var>.<var>screen_number</var> specifies the
X11 display name of the screen to grab from. <var>hostname</var> can be
omitted, and defaults to "localhost". The environment variable
<code>DISPLAY</code> contains the default display name.
</p>
<p><var>x_offset</var> and <var>y_offset</var> specify the offsets of the grabbed
area with respect to the top-left border of the X11 screen. They
default to 0.
</p>
<p>Check the X11 documentation (e.g. <code>man X</code>) for more detailed
information.
</p>
<p>Use the <code>xdpyinfo</code> program for getting basic information about
the properties of your X11 display (e.g. grep for "name" or
"dimensions").
</p>
<p>For example to grab from <samp>:0.0</samp> using <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0 out.mpg
</pre></div>
<p>Grab at position <code>10,20</code>:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
</pre></div>
<a name="Options-60"></a>
<h4 class="subsection">26.21.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-60" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-60" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>draw_mouse</samp></dt>
<dd><p>Specify whether to draw the mouse pointer. A value of <code>0</code> specify
not to draw the pointer. Default value is <code>1</code>.
</p>
</dd>
<dt><samp>follow_mouse</samp></dt>
<dd><p>Make the grabbed area follow the mouse. The argument can be
<code>centered</code> or a number of pixels <var>PIXELS</var>.
</p>
<p>When it is specified with "centered", the grabbing region follows the mouse
pointer and keeps the pointer at the center of region; otherwise, the region
follows only when the mouse pointer reaches within <var>PIXELS</var> (greater than
zero) to the edge of region.
</p>
<p>For example:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -follow_mouse centered -framerate 25 -video_size cif -i :0.0 out.mpg
</pre></div>
<p>To follow only when the mouse pointer reaches within 100 pixels to edge:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -follow_mouse 100 -framerate 25 -video_size cif -i :0.0 out.mpg
</pre></div>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>Set the grabbing frame rate. Default value is <code>ntsc</code>,
corresponding to a frame rate of <code>30000/1001</code>.
</p>
</dd>
<dt><samp>show_region</samp></dt>
<dd><p>Show grabbed region on screen.
</p>
<p>If <var>show_region</var> is specified with <code>1</code>, then the grabbing
region will be indicated on screen. With this option, it is easy to
know what is being grabbed if only a portion of the screen is grabbed.
</p>
</dd>
<dt><samp>region_border</samp></dt>
<dd><p>Set the region border thickness if <samp>-show_region 1</samp> is used.
Range is 1 to 128 and default is 3 (XCB-based x11grab only).
</p>
<p>For example:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -show_region 1 -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
</pre></div>
<p>With <var>follow_mouse</var>:
</p><div class="example">
<pre class="example">ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
</pre></div>
</dd>
<dt><samp>video_size</samp></dt>
<dd><p>Set the video frame size. Default value is <code>vga</code>.
</p>
</dd>
<dt><samp>use_shm</samp></dt>
<dd><p>Use the MIT-SHM extension for shared memory. Default value is <code>1</code>.
It may be necessary to disable it for remote displays (legacy x11grab
only).
</p></dd>
</dl>
<a name="grab_005fx-grab_005fy-AVOption"></a>
<h4 class="subsection">26.21.2 <var>grab_x</var> <var>grab_y</var> AVOption<span class="pull-right"><a class="anchor hidden-xs" href="#grab_005fx-grab_005fy-AVOption" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-grab_005fx-grab_005fy-AVOption" aria-hidden="true">TOC</a></span></h4>
<p>The syntax is:
</p><div class="example">
<pre class="example">-grab_x <var>x_offset</var> -grab_y <var>y_offset</var>
</pre></div>
<p>Set the grabbing region coordinates. They are expressed as offset from the top left
corner of the X11 window. The default value is 0.
</p>
<a name="Output-Devices"></a>
<h2 class="chapter">27 Output Devices<span class="pull-right"><a class="anchor hidden-xs" href="#Output-Devices" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Output-Devices" aria-hidden="true">TOC</a></span></h2>
<p>Output devices are configured elements in FFmpeg that can write
multimedia data to an output device attached to your system.
</p>
<p>When you configure your FFmpeg build, all the supported output devices
are enabled by default. You can list all available ones using the
configure option "–list-outdevs".
</p>
<p>You can disable all the output devices using the configure option
"–disable-outdevs", and selectively enable an output device using the
option "–enable-outdev=<var>OUTDEV</var>", or you can disable a particular
input device using the option "–disable-outdev=<var>OUTDEV</var>".
</p>
<p>The option "-devices" of the ff* tools will display the list of
enabled output devices.
</p>
<p>A description of the currently available output devices follows.
</p>
<a name="alsa-1"></a>
<h3 class="section">27.1 alsa<span class="pull-right"><a class="anchor hidden-xs" href="#alsa-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-alsa-1" aria-hidden="true">TOC</a></span></h3>
<p>ALSA (Advanced Linux Sound Architecture) output device.
</p>
<a name="Examples-21"></a>
<h4 class="subsection">27.1.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-21" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-21" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Play a file on default ALSA device:
<div class="example">
<pre class="example">ffmpeg -i INPUT -f alsa default
</pre></div>
</li><li> Play a file on soundcard 1, audio device 7:
<div class="example">
<pre class="example">ffmpeg -i INPUT -f alsa hw:1,7
</pre></div>
</li></ul>
<a name="caca"></a>
<h3 class="section">27.2 caca<span class="pull-right"><a class="anchor hidden-xs" href="#caca" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-caca" aria-hidden="true">TOC</a></span></h3>
<p>CACA output device.
</p>
<p>This output device allows one to show a video stream in CACA window.
Only one CACA window is allowed per application, so you can
have only one instance of this output device in an application.
</p>
<p>To enable this output device you need to configure FFmpeg with
<code>--enable-libcaca</code>.
libcaca is a graphics library that outputs text instead of pixels.
</p>
<p>For more information about libcaca, check:
<a href="http://caca.zoy.org/wiki/libcaca">http://caca.zoy.org/wiki/libcaca</a>
</p>
<a name="Options-61"></a>
<h4 class="subsection">27.2.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-61" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-61" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>window_title</samp></dt>
<dd><p>Set the CACA window title, if not specified default to the filename
specified for the output device.
</p>
</dd>
<dt><samp>window_size</samp></dt>
<dd><p>Set the CACA window size, can be a string of the form
<var>width</var>x<var>height</var> or a video size abbreviation.
If not specified it defaults to the size of the input video.
</p>
</dd>
<dt><samp>driver</samp></dt>
<dd><p>Set display driver.
</p>
</dd>
<dt><samp>algorithm</samp></dt>
<dd><p>Set dithering algorithm. Dithering is necessary
because the picture being rendered has usually far more colours than
the available palette.
The accepted values are listed with <code>-list_dither algorithms</code>.
</p>
</dd>
<dt><samp>antialias</samp></dt>
<dd><p>Set antialias method. Antialiasing smoothens the rendered
image and avoids the commonly seen staircase effect.
The accepted values are listed with <code>-list_dither antialiases</code>.
</p>
</dd>
<dt><samp>charset</samp></dt>
<dd><p>Set which characters are going to be used when rendering text.
The accepted values are listed with <code>-list_dither charsets</code>.
</p>
</dd>
<dt><samp>color</samp></dt>
<dd><p>Set color to be used when rendering text.
The accepted values are listed with <code>-list_dither colors</code>.
</p>
</dd>
<dt><samp>list_drivers</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of available drivers and exit.
</p>
</dd>
<dt><samp>list_dither</samp></dt>
<dd><p>List available dither options related to the argument.
The argument must be one of <code>algorithms</code>, <code>antialiases</code>,
<code>charsets</code>, <code>colors</code>.
</p></dd>
</dl>
<a name="Examples-22"></a>
<h4 class="subsection">27.2.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-22" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-22" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> The following command shows the <code>ffmpeg</code> output is an
CACA window, forcing its size to 80x25:
<div class="example">
<pre class="example">ffmpeg -i INPUT -vcodec rawvideo -pix_fmt rgb24 -window_size 80x25 -f caca -
</pre></div>
</li><li> Show the list of available drivers and exit:
<div class="example">
<pre class="example">ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_drivers true -
</pre></div>
</li><li> Show the list of available dither colors and exit:
<div class="example">
<pre class="example">ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_dither colors -
</pre></div>
</li></ul>
<a name="decklink-1"></a>
<h3 class="section">27.3 decklink<span class="pull-right"><a class="anchor hidden-xs" href="#decklink-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-decklink-1" aria-hidden="true">TOC</a></span></h3>
<p>The decklink output device provides playback capabilities for Blackmagic
DeckLink devices.
</p>
<p>To enable this output device, you need the Blackmagic DeckLink SDK and you
need to configure with the appropriate <code>--extra-cflags</code>
and <code>--extra-ldflags</code>.
On Windows, you need to run the IDL files through <code>widl</code>.
</p>
<p>DeckLink is very picky about the formats it supports. Pixel format is always
uyvy422, framerate and video size must be determined for your device with
<code>-list_formats 1</code>. Audio sample rate is always 48 kHz.
</p>
<a name="Options-62"></a>
<h4 class="subsection">27.3.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-62" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-62" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>list_devices</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of devices and exit.
Defaults to <samp>false</samp>.
</p>
</dd>
<dt><samp>list_formats</samp></dt>
<dd><p>If set to <samp>true</samp>, print a list of supported formats and exit.
Defaults to <samp>false</samp>.
</p>
</dd>
<dt><samp>preroll</samp></dt>
<dd><p>Amount of time to preroll video in seconds.
Defaults to <samp>0.5</samp>.
</p>
</dd>
</dl>
<a name="Examples-23"></a>
<h4 class="subsection">27.3.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-23" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-23" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> List output devices:
<div class="example">
<pre class="example">ffmpeg -i test.avi -f decklink -list_devices 1 dummy
</pre></div>
</li><li> List supported formats:
<div class="example">
<pre class="example">ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor'
</pre></div>
</li><li> Play video clip:
<div class="example">
<pre class="example">ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor'
</pre></div>
</li><li> Play video clip with non-standard framerate or video size:
<div class="example">
<pre class="example">ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor'
</pre></div>
</li></ul>
<a name="fbdev-1"></a>
<h3 class="section">27.4 fbdev<span class="pull-right"><a class="anchor hidden-xs" href="#fbdev-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fbdev-1" aria-hidden="true">TOC</a></span></h3>
<p>Linux framebuffer output device.
</p>
<p>The Linux framebuffer is a graphic hardware-independent abstraction
layer to show graphics on a computer monitor, typically on the
console. It is accessed through a file device node, usually
<samp>/dev/fb0</samp>.
</p>
<p>For more detailed information read the file
<samp>Documentation/fb/framebuffer.txt</samp> included in the Linux source tree.
</p>
<a name="Options-63"></a>
<h4 class="subsection">27.4.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-63" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-63" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>xoffset</samp></dt>
<dt><samp>yoffset</samp></dt>
<dd><p>Set x/y coordinate of top left corner. Default is 0.
</p></dd>
</dl>
<a name="Examples-24"></a>
<h4 class="subsection">27.4.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-24" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-24" aria-hidden="true">TOC</a></span></h4>
<p>Play a file on framebuffer device <samp>/dev/fb0</samp>.
Required pixel format depends on current framebuffer settings.
</p><div class="example">
<pre class="example">ffmpeg -re -i INPUT -vcodec rawvideo -pix_fmt bgra -f fbdev /dev/fb0
</pre></div>
<p>See also <a href="http://linux-fbdev.sourceforge.net/">http://linux-fbdev.sourceforge.net/</a>, and fbset(1).
</p>
<a name="opengl"></a>
<h3 class="section">27.5 opengl<span class="pull-right"><a class="anchor hidden-xs" href="#opengl" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-opengl" aria-hidden="true">TOC</a></span></h3>
<p>OpenGL output device.
</p>
<p>To enable this output device you need to configure FFmpeg with <code>--enable-opengl</code>.
</p>
<p>This output device allows one to render to OpenGL context.
Context may be provided by application or default SDL window is created.
</p>
<p>When device renders to external context, application must implement handlers for following messages:
<code>AV_DEV_TO_APP_CREATE_WINDOW_BUFFER</code> - create OpenGL context on current thread.
<code>AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER</code> - make OpenGL context current.
<code>AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER</code> - swap buffers.
<code>AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER</code> - destroy OpenGL context.
Application is also required to inform a device about current resolution by sending <code>AV_APP_TO_DEV_WINDOW_SIZE</code> message.
</p>
<a name="Options-64"></a>
<h4 class="subsection">27.5.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-64" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-64" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>background</samp></dt>
<dd><p>Set background color. Black is a default.
</p></dd>
<dt><samp>no_window</samp></dt>
<dd><p>Disables default SDL window when set to non-zero value.
Application must provide OpenGL context and both <code>window_size_cb</code> and <code>window_swap_buffers_cb</code> callbacks when set.
</p></dd>
<dt><samp>window_title</samp></dt>
<dd><p>Set the SDL window title, if not specified default to the filename specified for the output device.
Ignored when <samp>no_window</samp> is set.
</p></dd>
<dt><samp>window_size</samp></dt>
<dd><p>Set preferred window size, can be a string of the form widthxheight or a video size abbreviation.
If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.
Mostly usable when <samp>no_window</samp> is not set.
</p>
</dd>
</dl>
<a name="Examples-25"></a>
<h4 class="subsection">27.5.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-25" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-25" aria-hidden="true">TOC</a></span></h4>
<p>Play a file on SDL window using OpenGL rendering:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f opengl "window title"
</pre></div>
<a name="oss-1"></a>
<h3 class="section">27.6 oss<span class="pull-right"><a class="anchor hidden-xs" href="#oss-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-oss-1" aria-hidden="true">TOC</a></span></h3>
<p>OSS (Open Sound System) output device.
</p>
<a name="pulse-1"></a>
<h3 class="section">27.7 pulse<span class="pull-right"><a class="anchor hidden-xs" href="#pulse-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pulse-1" aria-hidden="true">TOC</a></span></h3>
<p>PulseAudio output device.
</p>
<p>To enable this output device you need to configure FFmpeg with <code>--enable-libpulse</code>.
</p>
<p>More information about PulseAudio can be found on <a href="http://www.pulseaudio.org">http://www.pulseaudio.org</a>
</p>
<a name="Options-65"></a>
<h4 class="subsection">27.7.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-65" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-65" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>server</samp></dt>
<dd><p>Connect to a specific PulseAudio server, specified by an IP address.
Default server is used when not provided.
</p>
</dd>
<dt><samp>name</samp></dt>
<dd><p>Specify the application name PulseAudio will use when showing active clients,
by default it is the <code>LIBAVFORMAT_IDENT</code> string.
</p>
</dd>
<dt><samp>stream_name</samp></dt>
<dd><p>Specify the stream name PulseAudio will use when showing active streams,
by default it is set to the specified output name.
</p>
</dd>
<dt><samp>device</samp></dt>
<dd><p>Specify the device to use. Default device is used when not provided.
List of output devices can be obtained with command <code>pactl list sinks</code>.
</p>
</dd>
<dt><samp>buffer_size</samp></dt>
<dt><samp>buffer_duration</samp></dt>
<dd><p>Control the size and duration of the PulseAudio buffer. A small buffer
gives more control, but requires more frequent updates.
</p>
<p><samp>buffer_size</samp> specifies size in bytes while
<samp>buffer_duration</samp> specifies duration in milliseconds.
</p>
<p>When both options are provided then the highest value is used
(duration is recalculated to bytes using stream parameters). If they
are set to 0 (which is default), the device will use the default
PulseAudio duration value. By default PulseAudio set buffer duration
to around 2 seconds.
</p>
</dd>
<dt><samp>prebuf</samp></dt>
<dd><p>Specify pre-buffering size in bytes. The server does not start with
playback before at least <samp>prebuf</samp> bytes are available in the
buffer. By default this option is initialized to the same value as
<samp>buffer_size</samp> or <samp>buffer_duration</samp> (whichever is bigger).
</p>
</dd>
<dt><samp>minreq</samp></dt>
<dd><p>Specify minimum request size in bytes. The server does not request less
than <samp>minreq</samp> bytes from the client, instead waits until the buffer
is free enough to request more bytes at once. It is recommended to not set
this option, which will initialize this to a value that is deemed sensible
by the server.
</p>
</dd>
</dl>
<a name="Examples-26"></a>
<h4 class="subsection">27.7.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-26" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-26" aria-hidden="true">TOC</a></span></h4>
<p>Play a file on default device on default server:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -f pulse "stream name"
</pre></div>
<a name="sdl"></a>
<h3 class="section">27.8 sdl<span class="pull-right"><a class="anchor hidden-xs" href="#sdl" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sdl" aria-hidden="true">TOC</a></span></h3>
<p>SDL (Simple DirectMedia Layer) output device.
</p>
<p>This output device allows one to show a video stream in an SDL
window. Only one SDL window is allowed per application, so you can
have only one instance of this output device in an application.
</p>
<p>To enable this output device you need libsdl installed on your system
when configuring your build.
</p>
<p>For more information about SDL, check:
<a href="http://www.libsdl.org/">http://www.libsdl.org/</a>
</p>
<a name="Options-66"></a>
<h4 class="subsection">27.8.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-66" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-66" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>window_title</samp></dt>
<dd><p>Set the SDL window title, if not specified default to the filename
specified for the output device.
</p>
</dd>
<dt><samp>icon_title</samp></dt>
<dd><p>Set the name of the iconified SDL window, if not specified it is set
to the same value of <var>window_title</var>.
</p>
</dd>
<dt><samp>window_size</samp></dt>
<dd><p>Set the SDL window size, can be a string of the form
<var>width</var>x<var>height</var> or a video size abbreviation.
If not specified it defaults to the size of the input video,
downscaled according to the aspect ratio.
</p>
</dd>
<dt><samp>window_fullscreen</samp></dt>
<dd><p>Set fullscreen mode when non-zero value is provided.
Default value is zero.
</p></dd>
</dl>
<a name="Interactive-commands"></a>
<h4 class="subsection">27.8.2 Interactive commands<span class="pull-right"><a class="anchor hidden-xs" href="#Interactive-commands" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Interactive-commands" aria-hidden="true">TOC</a></span></h4>
<p>The window created by the device can be controlled through the
following interactive commands.
</p>
<dl compact="compact">
<dt><tt class="key">q, ESC</tt></dt>
<dd><p>Quit the device immediately.
</p></dd>
</dl>
<a name="Examples-27"></a>
<h4 class="subsection">27.8.3 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-27" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-27" aria-hidden="true">TOC</a></span></h4>
<p>The following command shows the <code>ffmpeg</code> output is an
SDL window, forcing its size to the qcif format:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
</pre></div>
<a name="sndio-1"></a>
<h3 class="section">27.9 sndio<span class="pull-right"><a class="anchor hidden-xs" href="#sndio-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sndio-1" aria-hidden="true">TOC</a></span></h3>
<p>sndio audio output device.
</p>
<a name="xv"></a>
<h3 class="section">27.10 xv<span class="pull-right"><a class="anchor hidden-xs" href="#xv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-xv" aria-hidden="true">TOC</a></span></h3>
<p>XV (XVideo) output device.
</p>
<p>This output device allows one to show a video stream in a X Window System
window.
</p>
<a name="Options-67"></a>
<h4 class="subsection">27.10.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-67" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-67" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>display_name</samp></dt>
<dd><p>Specify the hardware display name, which determines the display and
communications domain to be used.
</p>
<p>The display name or DISPLAY environment variable can be a string in
the format <var>hostname</var>[:<var>number</var>[.<var>screen_number</var>]].
</p>
<p><var>hostname</var> specifies the name of the host machine on which the
display is physically attached. <var>number</var> specifies the number of
the display server on that host machine. <var>screen_number</var> specifies
the screen to be used on that server.
</p>
<p>If unspecified, it defaults to the value of the DISPLAY environment
variable.
</p>
<p>For example, <code>dual-headed:0.1</code> would specify screen 1 of display
0 on the machine named “dual-headed”.
</p>
<p>Check the X11 specification for more detailed information about the
display name format.
</p>
</dd>
<dt><samp>window_id</samp></dt>
<dd><p>When set to non-zero value then device doesn’t create new window,
but uses existing one with provided <var>window_id</var>. By default
this options is set to zero and device creates its own window.
</p>
</dd>
<dt><samp>window_size</samp></dt>
<dd><p>Set the created window size, can be a string of the form
<var>width</var>x<var>height</var> or a video size abbreviation. If not
specified it defaults to the size of the input video.
Ignored when <var>window_id</var> is set.
</p>
</dd>
<dt><samp>window_x</samp></dt>
<dt><samp>window_y</samp></dt>
<dd><p>Set the X and Y window offsets for the created window. They are both
set to 0 by default. The values may be ignored by the window manager.
Ignored when <var>window_id</var> is set.
</p>
</dd>
<dt><samp>window_title</samp></dt>
<dd><p>Set the window title, if not specified default to the filename
specified for the output device. Ignored when <var>window_id</var> is set.
</p></dd>
</dl>
<p>For more information about XVideo see <a href="http://www.x.org/">http://www.x.org/</a>.
</p>
<a name="Examples-28"></a>
<h4 class="subsection">27.10.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-28" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-28" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Decode, display and encode video input with <code>ffmpeg</code> at the
same time:
<div class="example">
<pre class="example">ffmpeg -i INPUT OUTPUT -f xv display
</pre></div>
</li><li> Decode and display the input video to multiple X11 windows:
<div class="example">
<pre class="example">ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
</pre></div>
</li></ul>
<a name="Resampler-Options"></a>
<h2 class="chapter">28 Resampler Options<span class="pull-right"><a class="anchor hidden-xs" href="#Resampler-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Resampler-Options" aria-hidden="true">TOC</a></span></h2>
<p>The audio resampler supports the following named options.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools, <var>option</var>=<var>value</var> for the aresample filter,
by setting the value explicitly in the
<code>SwrContext</code> options or using the <samp>libavutil/opt.h</samp> API for
programmatic use.
</p>
<dl compact="compact">
<dt><samp>ich, in_channel_count</samp></dt>
<dd><p>Set the number of input channels. Default value is 0. Setting this
value is not mandatory if the corresponding channel layout
<samp>in_channel_layout</samp> is set.
</p>
</dd>
<dt><samp>och, out_channel_count</samp></dt>
<dd><p>Set the number of output channels. Default value is 0. Setting this
value is not mandatory if the corresponding channel layout
<samp>out_channel_layout</samp> is set.
</p>
</dd>
<dt><samp>uch, used_channel_count</samp></dt>
<dd><p>Set the number of used input channels. Default value is 0. This option is
only used for special remapping.
</p>
</dd>
<dt><samp>isr, in_sample_rate</samp></dt>
<dd><p>Set the input sample rate. Default value is 0.
</p>
</dd>
<dt><samp>osr, out_sample_rate</samp></dt>
<dd><p>Set the output sample rate. Default value is 0.
</p>
</dd>
<dt><samp>isf, in_sample_fmt</samp></dt>
<dd><p>Specify the input sample format. It is set by default to <code>none</code>.
</p>
</dd>
<dt><samp>osf, out_sample_fmt</samp></dt>
<dd><p>Specify the output sample format. It is set by default to <code>none</code>.
</p>
</dd>
<dt><samp>tsf, internal_sample_fmt</samp></dt>
<dd><p>Set the internal sample format. Default value is <code>none</code>.
This will automatically be chosen when it is not explicitly set.
</p>
</dd>
<dt><samp>icl, in_channel_layout</samp></dt>
<dt><samp>ocl, out_channel_layout</samp></dt>
<dd><p>Set the input/output channel layout.
</p>
<p>See <a href="ffmpeg-utils.html#channel-layout-syntax">(ffmpeg-utils)the Channel Layout section in the ffmpeg-utils(1) manual</a>
for the required syntax.
</p>
</dd>
<dt><samp>clev, center_mix_level</samp></dt>
<dd><p>Set the center mix level. It is a value expressed in deciBel, and must be
in the interval [-32,32].
</p>
</dd>
<dt><samp>slev, surround_mix_level</samp></dt>
<dd><p>Set the surround mix level. It is a value expressed in deciBel, and must
be in the interval [-32,32].
</p>
</dd>
<dt><samp>lfe_mix_level</samp></dt>
<dd><p>Set LFE mix into non LFE level. It is used when there is a LFE input but no
LFE output. It is a value expressed in deciBel, and must
be in the interval [-32,32].
</p>
</dd>
<dt><samp>rmvol, rematrix_volume</samp></dt>
<dd><p>Set rematrix volume. Default value is 1.0.
</p>
</dd>
<dt><samp>rematrix_maxval</samp></dt>
<dd><p>Set maximum output value for rematrixing.
This can be used to prevent clipping vs. preventing volumn reduction
A value of 1.0 prevents cliping.
</p>
</dd>
<dt><samp>flags, swr_flags</samp></dt>
<dd><p>Set flags used by the converter. Default value is 0.
</p>
<p>It supports the following individual flags:
</p><dl compact="compact">
<dt><samp>res</samp></dt>
<dd><p>force resampling, this flag forces resampling to be used even when the
input and output sample rates match.
</p></dd>
</dl>
</dd>
<dt><samp>dither_scale</samp></dt>
<dd><p>Set the dither scale. Default value is 1.
</p>
</dd>
<dt><samp>dither_method</samp></dt>
<dd><p>Set dither method. Default value is 0.
</p>
<p>Supported values:
</p><dl compact="compact">
<dt>‘<samp>rectangular</samp>’</dt>
<dd><p>select rectangular dither
</p></dd>
<dt>‘<samp>triangular</samp>’</dt>
<dd><p>select triangular dither
</p></dd>
<dt>‘<samp>triangular_hp</samp>’</dt>
<dd><p>select triangular dither with high pass
</p></dd>
<dt>‘<samp>lipshitz</samp>’</dt>
<dd><p>select lipshitz noise shaping dither
</p></dd>
<dt>‘<samp>shibata</samp>’</dt>
<dd><p>select shibata noise shaping dither
</p></dd>
<dt>‘<samp>low_shibata</samp>’</dt>
<dd><p>select low shibata noise shaping dither
</p></dd>
<dt>‘<samp>high_shibata</samp>’</dt>
<dd><p>select high shibata noise shaping dither
</p></dd>
<dt>‘<samp>f_weighted</samp>’</dt>
<dd><p>select f-weighted noise shaping dither
</p></dd>
<dt>‘<samp>modified_e_weighted</samp>’</dt>
<dd><p>select modified-e-weighted noise shaping dither
</p></dd>
<dt>‘<samp>improved_e_weighted</samp>’</dt>
<dd><p>select improved-e-weighted noise shaping dither
</p>
</dd>
</dl>
</dd>
<dt><samp>resampler</samp></dt>
<dd><p>Set resampling engine. Default value is swr.
</p>
<p>Supported values:
</p><dl compact="compact">
<dt>‘<samp>swr</samp>’</dt>
<dd><p>select the native SW Resampler; filter options precision and cheby are not
applicable in this case.
</p></dd>
<dt>‘<samp>soxr</samp>’</dt>
<dd><p>select the SoX Resampler (where available); compensation, and filter options
filter_size, phase_shift, filter_type & kaiser_beta, are not applicable in this
case.
</p></dd>
</dl>
</dd>
<dt><samp>filter_size</samp></dt>
<dd><p>For swr only, set resampling filter size, default value is 32.
</p>
</dd>
<dt><samp>phase_shift</samp></dt>
<dd><p>For swr only, set resampling phase shift, default value is 10, and must be in
the interval [0,30].
</p>
</dd>
<dt><samp>linear_interp</samp></dt>
<dd><p>Use Linear Interpolation if set to 1, default value is 0.
</p>
</dd>
<dt><samp>cutoff</samp></dt>
<dd><p>Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float
value between 0 and 1. Default value is 0.97 with swr, and 0.91 with soxr
(which, with a sample-rate of 44100, preserves the entire audio band to 20kHz).
</p>
</dd>
<dt><samp>precision</samp></dt>
<dd><p>For soxr only, the precision in bits to which the resampled signal will be
calculated. The default value of 20 (which, with suitable dithering, is
appropriate for a destination bit-depth of 16) gives SoX’s ’High Quality’; a
value of 28 gives SoX’s ’Very High Quality’.
</p>
</dd>
<dt><samp>cheby</samp></dt>
<dd><p>For soxr only, selects passband rolloff none (Chebyshev) & higher-precision
approximation for ’irrational’ ratios. Default value is 0.
</p>
</dd>
<dt><samp>async</samp></dt>
<dd><p>For swr only, simple 1 parameter audio sync to timestamps using stretching,
squeezing, filling and trimming. Setting this to 1 will enable filling and
trimming, larger values represent the maximum amount in samples that the data
may be stretched or squeezed for each second.
Default value is 0, thus no compensation is applied to make the samples match
the audio timestamps.
</p>
</dd>
<dt><samp>first_pts</samp></dt>
<dd><p>For swr only, assume the first pts should be this value. The time unit is 1 / sample rate.
This allows for padding/trimming at the start of stream. By default, no
assumption is made about the first frame’s expected pts, so no padding or
trimming is done. For example, this could be set to 0 to pad the beginning with
silence if an audio stream starts after the video stream or to trim any samples
with a negative pts due to encoder delay.
</p>
</dd>
<dt><samp>min_comp</samp></dt>
<dd><p>For swr only, set the minimum difference between timestamps and audio data (in
seconds) to trigger stretching/squeezing/filling or trimming of the
data to make it match the timestamps. The default is that
stretching/squeezing/filling and trimming is disabled
(<samp>min_comp</samp> = <code>FLT_MAX</code>).
</p>
</dd>
<dt><samp>min_hard_comp</samp></dt>
<dd><p>For swr only, set the minimum difference between timestamps and audio data (in
seconds) to trigger adding/dropping samples to make it match the
timestamps. This option effectively is a threshold to select between
hard (trim/fill) and soft (squeeze/stretch) compensation. Note that
all compensation is by default disabled through <samp>min_comp</samp>.
The default is 0.1.
</p>
</dd>
<dt><samp>comp_duration</samp></dt>
<dd><p>For swr only, set duration (in seconds) over which data is stretched/squeezed
to make it match the timestamps. Must be a non-negative double float value,
default value is 1.0.
</p>
</dd>
<dt><samp>max_soft_comp</samp></dt>
<dd><p>For swr only, set maximum factor by which data is stretched/squeezed to make it
match the timestamps. Must be a non-negative double float value, default value
is 0.
</p>
</dd>
<dt><samp>matrix_encoding</samp></dt>
<dd><p>Select matrixed stereo encoding.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>select none
</p></dd>
<dt>‘<samp>dolby</samp>’</dt>
<dd><p>select Dolby
</p></dd>
<dt>‘<samp>dplii</samp>’</dt>
<dd><p>select Dolby Pro Logic II
</p></dd>
</dl>
<p>Default value is <code>none</code>.
</p>
</dd>
<dt><samp>filter_type</samp></dt>
<dd><p>For swr only, select resampling filter type. This only affects resampling
operations.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>cubic</samp>’</dt>
<dd><p>select cubic
</p></dd>
<dt>‘<samp>blackman_nuttall</samp>’</dt>
<dd><p>select Blackman Nuttall Windowed Sinc
</p></dd>
<dt>‘<samp>kaiser</samp>’</dt>
<dd><p>select Kaiser Windowed Sinc
</p></dd>
</dl>
</dd>
<dt><samp>kaiser_beta</samp></dt>
<dd><p>For swr only, set Kaiser Window Beta value. Must be an integer in the
interval [2,16], default value is 9.
</p>
</dd>
<dt><samp>output_sample_bits</samp></dt>
<dd><p>For swr only, set number of used output sample bits for dithering. Must be an integer in the
interval [0,64], default value is 0, which means it’s not used.
</p>
</dd>
</dl>
<a name="scaler_005foptions"></a><a name="Scaler-Options"></a>
<h2 class="chapter">29 Scaler Options<span class="pull-right"><a class="anchor hidden-xs" href="#Scaler-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Scaler-Options" aria-hidden="true">TOC</a></span></h2>
<p>The video scaler supports the following named options.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools. For programmatic use, they can be set explicitly in the
<code>SwsContext</code> options or through the <samp>libavutil/opt.h</samp> API.
</p>
<dl compact="compact">
<dd>
<a name="sws_005fflags"></a></dd>
<dt><samp>sws_flags</samp></dt>
<dd><p>Set the scaler flags. This is also used to set the scaling
algorithm. Only a single algorithm should be selected.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>fast_bilinear</samp>’</dt>
<dd><p>Select fast bilinear scaling algorithm.
</p>
</dd>
<dt>‘<samp>bilinear</samp>’</dt>
<dd><p>Select bilinear scaling algorithm.
</p>
</dd>
<dt>‘<samp>bicubic</samp>’</dt>
<dd><p>Select bicubic scaling algorithm.
</p>
</dd>
<dt>‘<samp>experimental</samp>’</dt>
<dd><p>Select experimental scaling algorithm.
</p>
</dd>
<dt>‘<samp>neighbor</samp>’</dt>
<dd><p>Select nearest neighbor rescaling algorithm.
</p>
</dd>
<dt>‘<samp>area</samp>’</dt>
<dd><p>Select averaging area rescaling algorithm.
</p>
</dd>
<dt>‘<samp>bicublin</samp>’</dt>
<dd><p>Select bicubic scaling algorithm for the luma component, bilinear for
chroma components.
</p>
</dd>
<dt>‘<samp>gauss</samp>’</dt>
<dd><p>Select Gaussian rescaling algorithm.
</p>
</dd>
<dt>‘<samp>sinc</samp>’</dt>
<dd><p>Select sinc rescaling algorithm.
</p>
</dd>
<dt>‘<samp>lanczos</samp>’</dt>
<dd><p>Select lanczos rescaling algorithm.
</p>
</dd>
<dt>‘<samp>spline</samp>’</dt>
<dd><p>Select natural bicubic spline rescaling algorithm.
</p>
</dd>
<dt>‘<samp>print_info</samp>’</dt>
<dd><p>Enable printing/debug logging.
</p>
</dd>
<dt>‘<samp>accurate_rnd</samp>’</dt>
<dd><p>Enable accurate rounding.
</p>
</dd>
<dt>‘<samp>full_chroma_int</samp>’</dt>
<dd><p>Enable full chroma interpolation.
</p>
</dd>
<dt>‘<samp>full_chroma_inp</samp>’</dt>
<dd><p>Select full chroma input.
</p>
</dd>
<dt>‘<samp>bitexact</samp>’</dt>
<dd><p>Enable bitexact output.
</p></dd>
</dl>
</dd>
<dt><samp>srcw</samp></dt>
<dd><p>Set source width.
</p>
</dd>
<dt><samp>srch</samp></dt>
<dd><p>Set source height.
</p>
</dd>
<dt><samp>dstw</samp></dt>
<dd><p>Set destination width.
</p>
</dd>
<dt><samp>dsth</samp></dt>
<dd><p>Set destination height.
</p>
</dd>
<dt><samp>src_format</samp></dt>
<dd><p>Set source pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp>dst_format</samp></dt>
<dd><p>Set destination pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp>src_range</samp></dt>
<dd><p>Select source range.
</p>
</dd>
<dt><samp>dst_range</samp></dt>
<dd><p>Select destination range.
</p>
</dd>
<dt><samp>param0, param1</samp></dt>
<dd><p>Set scaling algorithm parameters. The specified values are specific of
some scaling algorithms and ignored by others. The specified values
are floating point number values.
</p>
</dd>
<dt><samp>sws_dither</samp></dt>
<dd><p>Set the dithering algorithm. Accepts one of the following
values. Default value is ‘<samp>auto</samp>’.
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>automatic choice
</p>
</dd>
<dt>‘<samp>none</samp>’</dt>
<dd><p>no dithering
</p>
</dd>
<dt>‘<samp>bayer</samp>’</dt>
<dd><p>bayer dither
</p>
</dd>
<dt>‘<samp>ed</samp>’</dt>
<dd><p>error diffusion dither
</p>
</dd>
<dt>‘<samp>a_dither</samp>’</dt>
<dd><p>arithmetic dither, based using addition
</p>
</dd>
<dt>‘<samp>x_dither</samp>’</dt>
<dd><p>arithmetic dither, based using xor (more random/less apparent patterning that
a_dither).
</p>
</dd>
</dl>
</dd>
<dt><samp>alphablend</samp></dt>
<dd><p>Set the alpha blending to use when the input has alpha but the output does not.
Default value is ‘<samp>none</samp>’.
</p>
<dl compact="compact">
<dt>‘<samp>uniform_color</samp>’</dt>
<dd><p>Blend onto a uniform background color
</p>
</dd>
<dt>‘<samp>checkerboard</samp>’</dt>
<dd><p>Blend onto a checkerboard
</p>
</dd>
<dt>‘<samp>none</samp>’</dt>
<dd><p>No blending
</p>
</dd>
</dl>
</dd>
</dl>
<a name="Filtering-Introduction"></a>
<h2 class="chapter">30 Filtering Introduction<span class="pull-right"><a class="anchor hidden-xs" href="#Filtering-Introduction" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Filtering-Introduction" aria-hidden="true">TOC</a></span></h2>
<p>Filtering in FFmpeg is enabled through the libavfilter library.
</p>
<p>In libavfilter, a filter can have multiple inputs and multiple
outputs.
To illustrate the sorts of things that are possible, we consider the
following filtergraph.
</p>
<pre class="verbatim"> [main]
input --> split ---------------------> overlay --> output
| ^
|[tmp] [flip]|
+-----> crop --> vflip -------+
</pre>
<p>This filtergraph splits the input stream in two streams, then sends one
stream through the crop filter and the vflip filter, before merging it
back with the other stream by overlaying it on top. You can use the
following command to achieve this:
</p>
<div class="example">
<pre class="example">ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
</pre></div>
<p>The result will be that the top half of the video is mirrored
onto the bottom half of the output video.
</p>
<p>Filters in the same linear chain are separated by commas, and distinct
linear chains of filters are separated by semicolons. In our example,
<var>crop,vflip</var> are in one linear chain, <var>split</var> and
<var>overlay</var> are separately in another. The points where the linear
chains join are labelled by names enclosed in square brackets. In the
example, the split filter generates two outputs that are associated to
the labels <var>[main]</var> and <var>[tmp]</var>.
</p>
<p>The stream sent to the second output of <var>split</var>, labelled as
<var>[tmp]</var>, is processed through the <var>crop</var> filter, which crops
away the lower half part of the video, and then vertically flipped. The
<var>overlay</var> filter takes in input the first unchanged output of the
split filter (which was labelled as <var>[main]</var>), and overlay on its
lower half the output generated by the <var>crop,vflip</var> filterchain.
</p>
<p>Some filters take in input a list of parameters: they are specified
after the filter name and an equal sign, and are separated from each other
by a colon.
</p>
<p>There exist so-called <var>source filters</var> that do not have an
audio/video input, and <var>sink filters</var> that will not have audio/video
output.
</p>
<a name="graph2dot"></a>
<h2 class="chapter">31 graph2dot<span class="pull-right"><a class="anchor hidden-xs" href="#graph2dot" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-graph2dot" aria-hidden="true">TOC</a></span></h2>
<p>The <samp>graph2dot</samp> program included in the FFmpeg <samp>tools</samp>
directory can be used to parse a filtergraph description and issue a
corresponding textual representation in the dot language.
</p>
<p>Invoke the command:
</p><div class="example">
<pre class="example">graph2dot -h
</pre></div>
<p>to see how to use <samp>graph2dot</samp>.
</p>
<p>You can then pass the dot description to the <samp>dot</samp> program (from
the graphviz suite of programs) and obtain a graphical representation
of the filtergraph.
</p>
<p>For example the sequence of commands:
</p><div class="example">
<pre class="example">echo <var>GRAPH_DESCRIPTION</var> | \
tools/graph2dot -o graph.tmp && \
dot -Tpng graph.tmp -o graph.png && \
display graph.png
</pre></div>
<p>can be used to create and display an image representing the graph
described by the <var>GRAPH_DESCRIPTION</var> string. Note that this string must be
a complete self-contained graph, with its inputs and outputs explicitly defined.
For example if your command line is of the form:
</p><div class="example">
<pre class="example">ffmpeg -i infile -vf scale=640:360 outfile
</pre></div>
<p>your <var>GRAPH_DESCRIPTION</var> string will need to be of the form:
</p><div class="example">
<pre class="example">nullsrc,scale=640:360,nullsink
</pre></div>
<p>you may also need to set the <var>nullsrc</var> parameters and add a <var>format</var>
filter in order to simulate a specific input file.
</p>
<a name="Filtergraph-description"></a>
<h2 class="chapter">32 Filtergraph description<span class="pull-right"><a class="anchor hidden-xs" href="#Filtergraph-description" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Filtergraph-description" aria-hidden="true">TOC</a></span></h2>
<p>A filtergraph is a directed graph of connected filters. It can contain
cycles, and there can be multiple links between a pair of
filters. Each link has one input pad on one side connecting it to one
filter from which it takes its input, and one output pad on the other
side connecting it to one filter accepting its output.
</p>
<p>Each filter in a filtergraph is an instance of a filter class
registered in the application, which defines the features and the
number of input and output pads of the filter.
</p>
<p>A filter with no input pads is called a "source", and a filter with no
output pads is called a "sink".
</p>
<a name="Filtergraph-syntax"></a><a name="Filtergraph-syntax-1"></a>
<h3 class="section">32.1 Filtergraph syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Filtergraph-syntax-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Filtergraph-syntax-1" aria-hidden="true">TOC</a></span></h3>
<p>A filtergraph has a textual representation, which is recognized by the
<samp>-filter</samp>/<samp>-vf</samp>/<samp>-af</samp> and
<samp>-filter_complex</samp> options in <code>ffmpeg</code> and
<samp>-vf</samp>/<samp>-af</samp> in <code>ffplay</code>, and by the
<code>avfilter_graph_parse_ptr()</code> function defined in
<samp>libavfilter/avfilter.h</samp>.
</p>
<p>A filterchain consists of a sequence of connected filters, each one
connected to the previous one in the sequence. A filterchain is
represented by a list of ","-separated filter descriptions.
</p>
<p>A filtergraph consists of a sequence of filterchains. A sequence of
filterchains is represented by a list of ";"-separated filterchain
descriptions.
</p>
<p>A filter is represented by a string of the form:
[<var>in_link_1</var>]...[<var>in_link_N</var>]<var>filter_name</var>=<var>arguments</var>[<var>out_link_1</var>]...[<var>out_link_M</var>]
</p>
<p><var>filter_name</var> is the name of the filter class of which the
described filter is an instance of, and has to be the name of one of
the filter classes registered in the program.
The name of the filter class is optionally followed by a string
"=<var>arguments</var>".
</p>
<p><var>arguments</var> is a string which contains the parameters used to
initialize the filter instance. It may have one of two forms:
</p><ul>
<li> A ’:’-separated list of <var>key=value</var> pairs.
</li><li> A ’:’-separated list of <var>value</var>. In this case, the keys are assumed to be
the option names in the order they are declared. E.g. the <code>fade</code> filter
declares three options in this order – <samp>type</samp>, <samp>start_frame</samp> and
<samp>nb_frames</samp>. Then the parameter list <var>in:0:30</var> means that the value
<var>in</var> is assigned to the option <samp>type</samp>, <var>0</var> to
<samp>start_frame</samp> and <var>30</var> to <samp>nb_frames</samp>.
</li><li> A ’:’-separated list of mixed direct <var>value</var> and long <var>key=value</var>
pairs. The direct <var>value</var> must precede the <var>key=value</var> pairs, and
follow the same constraints order of the previous point. The following
<var>key=value</var> pairs can be set in any preferred order.
</li></ul>
<p>If the option value itself is a list of items (e.g. the <code>format</code> filter
takes a list of pixel formats), the items in the list are usually separated by
‘<samp>|</samp>’.
</p>
<p>The list of arguments can be quoted using the character ‘<samp>'</samp>’ as initial
and ending mark, and the character ‘<samp>\</samp>’ for escaping the characters
within the quoted text; otherwise the argument string is considered
terminated when the next special character (belonging to the set
‘<samp>[]=;,</samp>’) is encountered.
</p>
<p>The name and arguments of the filter are optionally preceded and
followed by a list of link labels.
A link label allows one to name a link and associate it to a filter output
or input pad. The preceding labels <var>in_link_1</var>
... <var>in_link_N</var>, are associated to the filter input pads,
the following labels <var>out_link_1</var> ... <var>out_link_M</var>, are
associated to the output pads.
</p>
<p>When two link labels with the same name are found in the
filtergraph, a link between the corresponding input and output pad is
created.
</p>
<p>If an output pad is not labelled, it is linked by default to the first
unlabelled input pad of the next filter in the filterchain.
For example in the filterchain
</p><div class="example">
<pre class="example">nullsrc, split[L1], [L2]overlay, nullsink
</pre></div>
<p>the split filter instance has two output pads, and the overlay filter
instance two input pads. The first output pad of split is labelled
"L1", the first input pad of overlay is labelled "L2", and the second
output pad of split is linked to the second input pad of overlay,
which are both unlabelled.
</p>
<p>In a filter description, if the input label of the first filter is not
specified, "in" is assumed; if the output label of the last filter is not
specified, "out" is assumed.
</p>
<p>In a complete filterchain all the unlabelled filter input and output
pads must be connected. A filtergraph is considered valid if all the
filter input and output pads of all the filterchains are connected.
</p>
<p>Libavfilter will automatically insert <a href="#scale">scale</a> filters where format
conversion is required. It is possible to specify swscale flags
for those automatically inserted scalers by prepending
<code>sws_flags=<var>flags</var>;</code>
to the filtergraph description.
</p>
<p>Here is a BNF description of the filtergraph syntax:
</p><div class="example">
<pre class="example"><var>NAME</var> ::= sequence of alphanumeric characters and '_'
<var>LINKLABEL</var> ::= "[" <var>NAME</var> "]"
<var>LINKLABELS</var> ::= <var>LINKLABEL</var> [<var>LINKLABELS</var>]
<var>FILTER_ARGUMENTS</var> ::= sequence of chars (possibly quoted)
<var>FILTER</var> ::= [<var>LINKLABELS</var>] <var>NAME</var> ["=" <var>FILTER_ARGUMENTS</var>] [<var>LINKLABELS</var>]
<var>FILTERCHAIN</var> ::= <var>FILTER</var> [,<var>FILTERCHAIN</var>]
<var>FILTERGRAPH</var> ::= [sws_flags=<var>flags</var>;] <var>FILTERCHAIN</var> [;<var>FILTERGRAPH</var>]
</pre></div>
<a name="Notes-on-filtergraph-escaping"></a>
<h3 class="section">32.2 Notes on filtergraph escaping<span class="pull-right"><a class="anchor hidden-xs" href="#Notes-on-filtergraph-escaping" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Notes-on-filtergraph-escaping" aria-hidden="true">TOC</a></span></h3>
<p>Filtergraph description composition entails several levels of
escaping. See <a href="ffmpeg-utils.html#quoting_005fand_005fescaping">(ffmpeg-utils)the "Quoting and escaping"
section in the ffmpeg-utils(1) manual</a> for more
information about the employed escaping procedure.
</p>
<p>A first level escaping affects the content of each filter option
value, which may contain the special character <code>:</code> used to
separate values, or one of the escaping characters <code>\'</code>.
</p>
<p>A second level escaping affects the whole filter description, which
may contain the escaping characters <code>\'</code> or the special
characters <code>[],;</code> used by the filtergraph description.
</p>
<p>Finally, when you specify a filtergraph on a shell commandline, you
need to perform a third level escaping for the shell special
characters contained within it.
</p>
<p>For example, consider the following string to be embedded in
the <a href="#drawtext">drawtext</a> filter description <samp>text</samp> value:
</p><div class="example">
<pre class="example">this is a 'string': may contain one, or more, special characters
</pre></div>
<p>This string contains the <code>'</code> special escaping character, and the
<code>:</code> special character, so it needs to be escaped in this way:
</p><div class="example">
<pre class="example">text=this is a \'string\'\: may contain one, or more, special characters
</pre></div>
<p>A second level of escaping is required when embedding the filter
description in a filtergraph description, in order to escape all the
filtergraph special characters. Thus the example above becomes:
</p><div class="example">
<pre class="example">drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
</pre></div>
<p>(note that in addition to the <code>\'</code> escaping special characters,
also <code>,</code> needs to be escaped).
</p>
<p>Finally an additional level of escaping is needed when writing the
filtergraph description in a shell command, which depends on the
escaping rules of the adopted shell. For example, assuming that
<code>\</code> is special and needs to be escaped with another <code>\</code>, the
previous string will finally result in:
</p><div class="example">
<pre class="example">-vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
</pre></div>
<a name="Timeline-editing"></a>
<h2 class="chapter">33 Timeline editing<span class="pull-right"><a class="anchor hidden-xs" href="#Timeline-editing" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Timeline-editing" aria-hidden="true">TOC</a></span></h2>
<p>Some filters support a generic <samp>enable</samp> option. For the filters
supporting timeline editing, this option can be set to an expression which is
evaluated before sending a frame to the filter. If the evaluation is non-zero,
the filter will be enabled, otherwise the frame will be sent unchanged to the
next filter in the filtergraph.
</p>
<p>The expression accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>t</samp>’</dt>
<dd><p>timestamp expressed in seconds, NAN if the input timestamp is unknown
</p>
</dd>
<dt>‘<samp>n</samp>’</dt>
<dd><p>sequential number of the input frame, starting from 0
</p>
</dd>
<dt>‘<samp>pos</samp>’</dt>
<dd><p>the position in the file of the input frame, NAN if unknown
</p>
</dd>
<dt>‘<samp>w</samp>’</dt>
<dt>‘<samp>h</samp>’</dt>
<dd><p>width and height of the input frame if video
</p></dd>
</dl>
<p>Additionally, these filters support an <samp>enable</samp> command that can be used
to re-define the expression.
</p>
<p>Like any other filtering option, the <samp>enable</samp> option follows the same
rules.
</p>
<p>For example, to enable a blur filter (<a href="#smartblur">smartblur</a>) from 10 seconds to 3
minutes, and a <a href="#curves">curves</a> filter starting at 3 seconds:
</p><div class="example">
<pre class="example">smartblur = enable='between(t,10,3*60)',
curves = enable='gte(t,3)' : preset=cross_process
</pre></div>
<a name="Audio-Filters"></a>
<h2 class="chapter">34 Audio Filters<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Filters" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Filters" aria-hidden="true">TOC</a></span></h2>
<p>When you configure your FFmpeg build, you can disable any of the
existing filters using <code>--disable-filters</code>.
The configure output will show the audio filters included in your
build.
</p>
<p>Below is a description of the currently available audio filters.
</p>
<a name="acrossfade"></a>
<h3 class="section">34.1 acrossfade<span class="pull-right"><a class="anchor hidden-xs" href="#acrossfade" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-acrossfade" aria-hidden="true">TOC</a></span></h3>
<p>Apply cross fade from one input audio stream to another input audio stream.
The cross fade is applied for specified duration near the end of first stream.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>nb_samples, ns</samp></dt>
<dd><p>Specify the number of samples for which the cross fade effect has to last.
At the end of the cross fade effect the first input audio will be completely
silent. Default is 44100.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Specify the duration of the cross fade effect. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
By default the duration is determined by <var>nb_samples</var>.
If set this option is used instead of <var>nb_samples</var>.
</p>
</dd>
<dt><samp>overlap, o</samp></dt>
<dd><p>Should first stream end overlap with second stream start. Default is enabled.
</p>
</dd>
<dt><samp>curve1</samp></dt>
<dd><p>Set curve for cross fade transition for first stream.
</p>
</dd>
<dt><samp>curve2</samp></dt>
<dd><p>Set curve for cross fade transition for second stream.
</p>
<p>For description of available curve types see <a href="#afade">afade</a> filter description.
</p></dd>
</dl>
<a name="Examples-29"></a>
<h4 class="subsection">34.1.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-29" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-29" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Cross fade from one input to another:
<div class="example">
<pre class="example">ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac
</pre></div>
</li><li> Cross fade from one input to another but without overlapping:
<div class="example">
<pre class="example">ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac
</pre></div>
</li></ul>
<a name="adelay"></a>
<h3 class="section">34.2 adelay<span class="pull-right"><a class="anchor hidden-xs" href="#adelay" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-adelay" aria-hidden="true">TOC</a></span></h3>
<p>Delay one or more audio channels.
</p>
<p>Samples in delayed channel are filled with silence.
</p>
<p>The filter accepts the following option:
</p>
<dl compact="compact">
<dt><samp>delays</samp></dt>
<dd><p>Set list of delays in milliseconds for each channel separated by ’|’.
At least one delay greater than 0 should be provided.
Unused delays will be silently ignored. If number of given delays is
smaller than number of channels all remaining channels will not be delayed.
</p></dd>
</dl>
<a name="Examples-30"></a>
<h4 class="subsection">34.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-30" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-30" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
the second channel (and any other channels that may be present) unchanged.
<div class="example">
<pre class="example">adelay=1500|0|500
</pre></div>
</li></ul>
<a name="aecho"></a>
<h3 class="section">34.3 aecho<span class="pull-right"><a class="anchor hidden-xs" href="#aecho" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aecho" aria-hidden="true">TOC</a></span></h3>
<p>Apply echoing to the input audio.
</p>
<p>Echoes are reflected sound and can occur naturally amongst mountains
(and sometimes large buildings) when talking or shouting; digital echo
effects emulate this behaviour and are often used to help fill out the
sound of a single instrument or vocal. The time difference between the
original signal and the reflection is the <code>delay</code>, and the
loudness of the reflected signal is the <code>decay</code>.
Multiple echoes can have different delays and decays.
</p>
<p>A description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>in_gain</samp></dt>
<dd><p>Set input gain of reflected signal. Default is <code>0.6</code>.
</p>
</dd>
<dt><samp>out_gain</samp></dt>
<dd><p>Set output gain of reflected signal. Default is <code>0.3</code>.
</p>
</dd>
<dt><samp>delays</samp></dt>
<dd><p>Set list of time intervals in milliseconds between original signal and reflections
separated by ’|’. Allowed range for each <code>delay</code> is <code>(0 - 90000.0]</code>.
Default is <code>1000</code>.
</p>
</dd>
<dt><samp>decays</samp></dt>
<dd><p>Set list of loudnesses of reflected signals separated by ’|’.
Allowed range for each <code>decay</code> is <code>(0 - 1.0]</code>.
Default is <code>0.5</code>.
</p></dd>
</dl>
<a name="Examples-31"></a>
<h4 class="subsection">34.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-31" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-31" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Make it sound as if there are twice as many instruments as are actually playing:
<div class="example">
<pre class="example">aecho=0.8:0.88:60:0.4
</pre></div>
</li><li> If delay is very short, then it sound like a (metallic) robot playing music:
<div class="example">
<pre class="example">aecho=0.8:0.88:6:0.4
</pre></div>
</li><li> A longer delay will sound like an open air concert in the mountains:
<div class="example">
<pre class="example">aecho=0.8:0.9:1000:0.3
</pre></div>
</li><li> Same as above but with one more mountain:
<div class="example">
<pre class="example">aecho=0.8:0.9:1000|1800:0.3|0.25
</pre></div>
</li></ul>
<a name="aeval"></a>
<h3 class="section">34.4 aeval<span class="pull-right"><a class="anchor hidden-xs" href="#aeval" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aeval" aria-hidden="true">TOC</a></span></h3>
<p>Modify an audio signal according to the specified expressions.
</p>
<p>This filter accepts one or more expressions (one for each channel),
which are evaluated and used to modify a corresponding audio signal.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>exprs</samp></dt>
<dd><p>Set the ’|’-separated expressions list for each separate channel. If
the number of input channels is greater than the number of
expressions, the last specified expression is used for the remaining
output channels.
</p>
</dd>
<dt><samp>channel_layout, c</samp></dt>
<dd><p>Set output channel layout. If not specified, the channel layout is
specified by the number of expressions. If set to ‘<samp>same</samp>’, it will
use by default the same input channel layout.
</p></dd>
</dl>
<p>Each expression in <var>exprs</var> can contain the following constants and functions:
</p>
<dl compact="compact">
<dt><samp>ch</samp></dt>
<dd><p>channel number of the current expression
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>number of the evaluated sample, starting from 0
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>sample rate
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>time of the evaluated sample expressed in seconds
</p>
</dd>
<dt><samp>nb_in_channels</samp></dt>
<dt><samp>nb_out_channels</samp></dt>
<dd><p>input and output number of channels
</p>
</dd>
<dt><samp>val(CH)</samp></dt>
<dd><p>the value of input channel with number <var>CH</var>
</p></dd>
</dl>
<p>Note: this filter is slow. For faster processing you should use a
dedicated filter.
</p>
<a name="Examples-32"></a>
<h4 class="subsection">34.4.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-32" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-32" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Half volume:
<div class="example">
<pre class="example">aeval=val(ch)/2:c=same
</pre></div>
</li><li> Invert phase of the second channel:
<div class="example">
<pre class="example">aeval=val(0)|-val(1)
</pre></div>
</li></ul>
<a name="afade"></a><a name="afade-1"></a>
<h3 class="section">34.5 afade<span class="pull-right"><a class="anchor hidden-xs" href="#afade-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-afade-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply fade-in/out effect to input audio.
</p>
<p>A description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>type, t</samp></dt>
<dd><p>Specify the effect type, can be either <code>in</code> for fade-in, or
<code>out</code> for a fade-out effect. Default is <code>in</code>.
</p>
</dd>
<dt><samp>start_sample, ss</samp></dt>
<dd><p>Specify the number of the start sample for starting to apply the fade
effect. Default is 0.
</p>
</dd>
<dt><samp>nb_samples, ns</samp></dt>
<dd><p>Specify the number of samples for which the fade effect has to last. At
the end of the fade-in effect the output audio will have the same
volume as the input audio, at the end of the fade-out transition
the output audio will be silence. Default is 44100.
</p>
</dd>
<dt><samp>start_time, st</samp></dt>
<dd><p>Specify the start time of the fade effect. Default is 0.
The value must be specified as a time duration; see
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
If set this option is used instead of <var>start_sample</var>.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Specify the duration of the fade effect. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
At the end of the fade-in effect the output audio will have the same
volume as the input audio, at the end of the fade-out transition
the output audio will be silence.
By default the duration is determined by <var>nb_samples</var>.
If set this option is used instead of <var>nb_samples</var>.
</p>
</dd>
<dt><samp>curve</samp></dt>
<dd><p>Set curve for fade transition.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt><samp>tri</samp></dt>
<dd><p>select triangular, linear slope (default)
</p></dd>
<dt><samp>qsin</samp></dt>
<dd><p>select quarter of sine wave
</p></dd>
<dt><samp>hsin</samp></dt>
<dd><p>select half of sine wave
</p></dd>
<dt><samp>esin</samp></dt>
<dd><p>select exponential sine wave
</p></dd>
<dt><samp>log</samp></dt>
<dd><p>select logarithmic
</p></dd>
<dt><samp>ipar</samp></dt>
<dd><p>select inverted parabola
</p></dd>
<dt><samp>qua</samp></dt>
<dd><p>select quadratic
</p></dd>
<dt><samp>cub</samp></dt>
<dd><p>select cubic
</p></dd>
<dt><samp>squ</samp></dt>
<dd><p>select square root
</p></dd>
<dt><samp>cbr</samp></dt>
<dd><p>select cubic root
</p></dd>
<dt><samp>par</samp></dt>
<dd><p>select parabola
</p></dd>
<dt><samp>exp</samp></dt>
<dd><p>select exponential
</p></dd>
<dt><samp>iqsin</samp></dt>
<dd><p>select inverted quarter of sine wave
</p></dd>
<dt><samp>ihsin</samp></dt>
<dd><p>select inverted half of sine wave
</p></dd>
<dt><samp>dese</samp></dt>
<dd><p>select double-exponential seat
</p></dd>
<dt><samp>desi</samp></dt>
<dd><p>select double-exponential sigmoid
</p></dd>
</dl>
</dd>
</dl>
<a name="Examples-33"></a>
<h4 class="subsection">34.5.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-33" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-33" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Fade in first 15 seconds of audio:
<div class="example">
<pre class="example">afade=t=in:ss=0:d=15
</pre></div>
</li><li> Fade out last 25 seconds of a 900 seconds audio:
<div class="example">
<pre class="example">afade=t=out:st=875:d=25
</pre></div>
</li></ul>
<a name="aformat"></a><a name="aformat-1"></a>
<h3 class="section">34.6 aformat<span class="pull-right"><a class="anchor hidden-xs" href="#aformat-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aformat-1" aria-hidden="true">TOC</a></span></h3>
<p>Set output format constraints for the input audio. The framework will
negotiate the most appropriate format to minimize conversions.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>sample_fmts</samp></dt>
<dd><p>A ’|’-separated list of requested sample formats.
</p>
</dd>
<dt><samp>sample_rates</samp></dt>
<dd><p>A ’|’-separated list of requested sample rates.
</p>
</dd>
<dt><samp>channel_layouts</samp></dt>
<dd><p>A ’|’-separated list of requested channel layouts.
</p>
<p>See <a href="ffmpeg-utils.html#channel-layout-syntax">(ffmpeg-utils)the Channel Layout section in the ffmpeg-utils(1) manual</a>
for the required syntax.
</p></dd>
</dl>
<p>If a parameter is omitted, all values are allowed.
</p>
<p>Force the output to either unsigned 8-bit or signed 16-bit stereo
</p><div class="example">
<pre class="example">aformat=sample_fmts=u8|s16:channel_layouts=stereo
</pre></div>
<a name="allpass"></a>
<h3 class="section">34.7 allpass<span class="pull-right"><a class="anchor hidden-xs" href="#allpass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-allpass" aria-hidden="true">TOC</a></span></h3>
<p>Apply a two-pole all-pass filter with central frequency (in Hz)
<var>frequency</var>, and filter-width <var>width</var>.
An all-pass filter changes the audio’s frequency to phase relationship
without changing its frequency to amplitude relationship.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set frequency in Hz.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
</p></dd>
</dl>
<a name="amerge"></a><a name="amerge-1"></a>
<h3 class="section">34.8 amerge<span class="pull-right"><a class="anchor hidden-xs" href="#amerge-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-amerge-1" aria-hidden="true">TOC</a></span></h3>
<p>Merge two or more audio streams into a single multi-channel stream.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>inputs</samp></dt>
<dd><p>Set the number of inputs. Default is 2.
</p>
</dd>
</dl>
<p>If the channel layouts of the inputs are disjoint, and therefore compatible,
the channel layout of the output will be set accordingly and the channels
will be reordered as necessary. If the channel layouts of the inputs are not
disjoint, the output will have all the channels of the first input then all
the channels of the second input, in that order, and the channel layout of
the output will be the default value corresponding to the total number of
channels.
</p>
<p>For example, if the first input is in 2.1 (FL+FR+LF) and the second input
is FC+BL+BR, then the output will be in 5.1, with the channels in the
following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
first input, b1 is the first channel of the second input).
</p>
<p>On the other hand, if both input are in stereo, the output channels will be
in the default order: a1, a2, b1, b2, and the channel layout will be
arbitrarily set to 4.0, which may or may not be the expected value.
</p>
<p>All inputs must have the same sample rate, and format.
</p>
<p>If inputs do not have the same duration, the output will stop with the
shortest.
</p>
<a name="Examples-34"></a>
<h4 class="subsection">34.8.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-34" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-34" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Merge two mono files into a stereo stream:
<div class="example">
<pre class="example">amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
</pre></div>
</li><li> Multiple merges assuming 1 video stream and 6 audio streams in <samp>input.mkv</samp>:
<div class="example">
<pre class="example">ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
</pre></div>
</li></ul>
<a name="amix"></a>
<h3 class="section">34.9 amix<span class="pull-right"><a class="anchor hidden-xs" href="#amix" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-amix" aria-hidden="true">TOC</a></span></h3>
<p>Mixes multiple audio inputs into a single output.
</p>
<p>Note that this filter only supports float samples (the <var>amerge</var>
and <var>pan</var> audio filters support many formats). If the <var>amix</var>
input has integer samples then <a href="#aresample">aresample</a> will be automatically
inserted to perform the conversion to float samples.
</p>
<p>For example
</p><div class="example">
<pre class="example">ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
</pre></div>
<p>will mix 3 input audio streams to a single output with the same duration as the
first input and a dropout transition time of 3 seconds.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>inputs</samp></dt>
<dd><p>The number of inputs. If unspecified, it defaults to 2.
</p>
</dd>
<dt><samp>duration</samp></dt>
<dd><p>How to determine the end-of-stream.
</p><dl compact="compact">
<dt><samp>longest</samp></dt>
<dd><p>The duration of the longest input. (default)
</p>
</dd>
<dt><samp>shortest</samp></dt>
<dd><p>The duration of the shortest input.
</p>
</dd>
<dt><samp>first</samp></dt>
<dd><p>The duration of the first input.
</p>
</dd>
</dl>
</dd>
<dt><samp>dropout_transition</samp></dt>
<dd><p>The transition time, in seconds, for volume renormalization when an input
stream ends. The default value is 2 seconds.
</p>
</dd>
</dl>
<a name="anull"></a>
<h3 class="section">34.10 anull<span class="pull-right"><a class="anchor hidden-xs" href="#anull" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-anull" aria-hidden="true">TOC</a></span></h3>
<p>Pass the audio source unchanged to the output.
</p>
<a name="apad"></a>
<h3 class="section">34.11 apad<span class="pull-right"><a class="anchor hidden-xs" href="#apad" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-apad" aria-hidden="true">TOC</a></span></h3>
<p>Pad the end of an audio stream with silence.
</p>
<p>This can be used together with <code>ffmpeg</code> <samp>-shortest</samp> to
extend audio streams to the same length as the video stream.
</p>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>packet_size</samp></dt>
<dd><p>Set silence packet size. Default value is 4096.
</p>
</dd>
<dt><samp>pad_len</samp></dt>
<dd><p>Set the number of samples of silence to add to the end. After the
value is reached, the stream is terminated. This option is mutually
exclusive with <samp>whole_len</samp>.
</p>
</dd>
<dt><samp>whole_len</samp></dt>
<dd><p>Set the minimum total number of samples in the output audio stream. If
the value is longer than the input audio length, silence is added to
the end, until the value is reached. This option is mutually exclusive
with <samp>pad_len</samp>.
</p></dd>
</dl>
<p>If neither the <samp>pad_len</samp> nor the <samp>whole_len</samp> option is
set, the filter will add silence to the end of the input stream
indefinitely.
</p>
<a name="Examples-35"></a>
<h4 class="subsection">34.11.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-35" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-35" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Add 1024 samples of silence to the end of the input:
<div class="example">
<pre class="example">apad=pad_len=1024
</pre></div>
</li><li> Make sure the audio output will contain at least 10000 samples, pad
the input with silence if required:
<div class="example">
<pre class="example">apad=whole_len=10000
</pre></div>
</li><li> Use <code>ffmpeg</code> to pad the audio input with silence, so that the
video stream will always result the shortest and will be converted
until the end in the output file when using the <samp>shortest</samp>
option:
<div class="example">
<pre class="example">ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
</pre></div>
</li></ul>
<a name="aphaser"></a>
<h3 class="section">34.12 aphaser<span class="pull-right"><a class="anchor hidden-xs" href="#aphaser" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aphaser" aria-hidden="true">TOC</a></span></h3>
<p>Add a phasing effect to the input audio.
</p>
<p>A phaser filter creates series of peaks and troughs in the frequency spectrum.
The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
</p>
<p>A description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>in_gain</samp></dt>
<dd><p>Set input gain. Default is 0.4.
</p>
</dd>
<dt><samp>out_gain</samp></dt>
<dd><p>Set output gain. Default is 0.74
</p>
</dd>
<dt><samp>delay</samp></dt>
<dd><p>Set delay in milliseconds. Default is 3.0.
</p>
</dd>
<dt><samp>decay</samp></dt>
<dd><p>Set decay. Default is 0.4.
</p>
</dd>
<dt><samp>speed</samp></dt>
<dd><p>Set modulation speed in Hz. Default is 0.5.
</p>
</dd>
<dt><samp>type</samp></dt>
<dd><p>Set modulation type. Default is triangular.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>triangular, t</samp>’</dt>
<dt>‘<samp>sinusoidal, s</samp>’</dt>
</dl>
</dd>
</dl>
<a name="aresample"></a><a name="aresample-1"></a>
<h3 class="section">34.13 aresample<span class="pull-right"><a class="anchor hidden-xs" href="#aresample-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aresample-1" aria-hidden="true">TOC</a></span></h3>
<p>Resample the input audio to the specified parameters, using the
libswresample library. If none are specified then the filter will
automatically convert between its input and output.
</p>
<p>This filter is also able to stretch/squeeze the audio data to make it match
the timestamps or to inject silence / cut out audio to make it match the
timestamps, do a combination of both or do neither.
</p>
<p>The filter accepts the syntax
[<var>sample_rate</var>:]<var>resampler_options</var>, where <var>sample_rate</var>
expresses a sample rate and <var>resampler_options</var> is a list of
<var>key</var>=<var>value</var> pairs, separated by ":". See the
ffmpeg-resampler manual for the complete list of supported options.
</p>
<a name="Examples-36"></a>
<h4 class="subsection">34.13.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-36" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-36" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Resample the input audio to 44100Hz:
<div class="example">
<pre class="example">aresample=44100
</pre></div>
</li><li> Stretch/squeeze samples to the given timestamps, with a maximum of 1000
samples per second compensation:
<div class="example">
<pre class="example">aresample=async=1000
</pre></div>
</li></ul>
<a name="asetnsamples"></a>
<h3 class="section">34.14 asetnsamples<span class="pull-right"><a class="anchor hidden-xs" href="#asetnsamples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-asetnsamples" aria-hidden="true">TOC</a></span></h3>
<p>Set the number of samples per each output audio frame.
</p>
<p>The last output packet may contain a different number of samples, as
the filter will flush all the remaining samples when the input audio
signal its end.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>nb_out_samples, n</samp></dt>
<dd><p>Set the number of frames per each output audio frame. The number is
intended as the number of samples <em>per each channel</em>.
Default value is 1024.
</p>
</dd>
<dt><samp>pad, p</samp></dt>
<dd><p>If set to 1, the filter will pad the last audio frame with zeroes, so
that the last frame will contain the same number of samples as the
previous ones. Default value is 1.
</p></dd>
</dl>
<p>For example, to set the number of per-frame samples to 1234 and
disable padding for the last frame, use:
</p><div class="example">
<pre class="example">asetnsamples=n=1234:p=0
</pre></div>
<a name="asetrate"></a>
<h3 class="section">34.15 asetrate<span class="pull-right"><a class="anchor hidden-xs" href="#asetrate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-asetrate" aria-hidden="true">TOC</a></span></h3>
<p>Set the sample rate without altering the PCM data.
This will result in a change of speed and pitch.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>sample_rate, r</samp></dt>
<dd><p>Set the output sample rate. Default is 44100 Hz.
</p></dd>
</dl>
<a name="ashowinfo"></a>
<h3 class="section">34.16 ashowinfo<span class="pull-right"><a class="anchor hidden-xs" href="#ashowinfo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ashowinfo" aria-hidden="true">TOC</a></span></h3>
<p>Show a line containing various information for each input audio frame.
The input audio is not modified.
</p>
<p>The shown line contains a sequence of key/value pairs of the form
<var>key</var>:<var>value</var>.
</p>
<p>The following values are shown in the output:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>The (sequential) number of the input frame, starting from 0.
</p>
</dd>
<dt><samp>pts</samp></dt>
<dd><p>The presentation timestamp of the input frame, in time base units; the time base
depends on the filter input pad, and is usually 1/<var>sample_rate</var>.
</p>
</dd>
<dt><samp>pts_time</samp></dt>
<dd><p>The presentation timestamp of the input frame in seconds.
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>position of the frame in the input stream, -1 if this information in
unavailable and/or meaningless (for example in case of synthetic audio)
</p>
</dd>
<dt><samp>fmt</samp></dt>
<dd><p>The sample format.
</p>
</dd>
<dt><samp>chlayout</samp></dt>
<dd><p>The channel layout.
</p>
</dd>
<dt><samp>rate</samp></dt>
<dd><p>The sample rate for the audio frame.
</p>
</dd>
<dt><samp>nb_samples</samp></dt>
<dd><p>The number of samples (per channel) in the frame.
</p>
</dd>
<dt><samp>checksum</samp></dt>
<dd><p>The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
audio, the data is treated as if all the planes were concatenated.
</p>
</dd>
<dt><samp>plane_checksums</samp></dt>
<dd><p>A list of Adler-32 checksums for each data plane.
</p></dd>
</dl>
<a name="astats"></a><a name="astats-1"></a>
<h3 class="section">34.17 astats<span class="pull-right"><a class="anchor hidden-xs" href="#astats-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-astats-1" aria-hidden="true">TOC</a></span></h3>
<p>Display time domain statistical information about the audio channels.
Statistics are calculated and displayed for each audio channel and,
where applicable, an overall figure is also given.
</p>
<p>It accepts the following option:
</p><dl compact="compact">
<dt><samp>length</samp></dt>
<dd><p>Short window length in seconds, used for peak and trough RMS measurement.
Default is <code>0.05</code> (50 milliseconds). Allowed range is <code>[0.1 - 10]</code>.
</p>
</dd>
<dt><samp>metadata</samp></dt>
<dd>
<p>Set metadata injection. All the metadata keys are prefixed with <code>lavfi.astats.X</code>,
where <code>X</code> is channel number starting from 1 or string <code>Overall</code>. Default is
disabled.
</p>
<p>Available keys for each channel are:
DC_offset
Min_level
Max_level
Min_difference
Max_difference
Mean_difference
Peak_level
RMS_peak
RMS_trough
Crest_factor
Flat_factor
Peak_count
Bit_depth
</p>
<p>and for Overall:
DC_offset
Min_level
Max_level
Min_difference
Max_difference
Mean_difference
Peak_level
RMS_level
RMS_peak
RMS_trough
Flat_factor
Peak_count
Bit_depth
Number_of_samples
</p>
<p>For example full key look like this <code>lavfi.astats.1.DC_offset</code> or
this <code>lavfi.astats.Overall.Peak_count</code>.
</p>
<p>For description what each key means read below.
</p>
</dd>
<dt><samp>reset</samp></dt>
<dd><p>Set number of frame after which stats are going to be recalculated.
Default is disabled.
</p></dd>
</dl>
<p>A description of each shown parameter follows:
</p>
<dl compact="compact">
<dt><samp>DC offset</samp></dt>
<dd><p>Mean amplitude displacement from zero.
</p>
</dd>
<dt><samp>Min level</samp></dt>
<dd><p>Minimal sample level.
</p>
</dd>
<dt><samp>Max level</samp></dt>
<dd><p>Maximal sample level.
</p>
</dd>
<dt><samp>Min difference</samp></dt>
<dd><p>Minimal difference between two consecutive samples.
</p>
</dd>
<dt><samp>Max difference</samp></dt>
<dd><p>Maximal difference between two consecutive samples.
</p>
</dd>
<dt><samp>Mean difference</samp></dt>
<dd><p>Mean difference between two consecutive samples.
The average of each difference between two consecutive samples.
</p>
</dd>
<dt><samp>Peak level dB</samp></dt>
<dt><samp>RMS level dB</samp></dt>
<dd><p>Standard peak and RMS level measured in dBFS.
</p>
</dd>
<dt><samp>RMS peak dB</samp></dt>
<dt><samp>RMS trough dB</samp></dt>
<dd><p>Peak and trough values for RMS level measured over a short window.
</p>
</dd>
<dt><samp>Crest factor</samp></dt>
<dd><p>Standard ratio of peak to RMS level (note: not in dB).
</p>
</dd>
<dt><samp>Flat factor</samp></dt>
<dd><p>Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
(i.e. either <var>Min level</var> or <var>Max level</var>).
</p>
</dd>
<dt><samp>Peak count</samp></dt>
<dd><p>Number of occasions (not the number of samples) that the signal attained either
<var>Min level</var> or <var>Max level</var>.
</p>
</dd>
<dt><samp>Bit depth</samp></dt>
<dd><p>Overall bit depth of audio. Number of bits used for each sample.
</p></dd>
</dl>
<a name="astreamsync"></a>
<h3 class="section">34.18 astreamsync<span class="pull-right"><a class="anchor hidden-xs" href="#astreamsync" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-astreamsync" aria-hidden="true">TOC</a></span></h3>
<p>Forward two audio streams and control the order the buffers are forwarded.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>expr, e</samp></dt>
<dd><p>Set the expression deciding which stream should be
forwarded next: if the result is negative, the first stream is forwarded; if
the result is positive or zero, the second stream is forwarded. It can use
the following variables:
</p>
<dl compact="compact">
<dt><var>b1 b2</var></dt>
<dd><p>number of buffers forwarded so far on each stream
</p></dd>
<dt><var>s1 s2</var></dt>
<dd><p>number of samples forwarded so far on each stream
</p></dd>
<dt><var>t1 t2</var></dt>
<dd><p>current timestamp of each stream
</p></dd>
</dl>
<p>The default value is <code>t1-t2</code>, which means to always forward the stream
that has a smaller timestamp.
</p></dd>
</dl>
<a name="Examples-37"></a>
<h4 class="subsection">34.18.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-37" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-37" aria-hidden="true">TOC</a></span></h4>
<p>Stress-test <code>amerge</code> by randomly sending buffers on the wrong
input, while avoiding too much of a desynchronization:
</p><div class="example">
<pre class="example">amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
[a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
[a2] [b2] amerge
</pre></div>
<a name="asyncts"></a>
<h3 class="section">34.19 asyncts<span class="pull-right"><a class="anchor hidden-xs" href="#asyncts" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-asyncts" aria-hidden="true">TOC</a></span></h3>
<p>Synchronize audio data with timestamps by squeezing/stretching it and/or
dropping samples/adding silence when needed.
</p>
<p>This filter is not built by default, please use <a href="#aresample">aresample</a> to do squeezing/stretching.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>compensate</samp></dt>
<dd><p>Enable stretching/squeezing the data to make it match the timestamps. Disabled
by default. When disabled, time gaps are covered with silence.
</p>
</dd>
<dt><samp>min_delta</samp></dt>
<dd><p>The minimum difference between timestamps and audio data (in seconds) to trigger
adding/dropping samples. The default value is 0.1. If you get an imperfect
sync with this filter, try setting this parameter to 0.
</p>
</dd>
<dt><samp>max_comp</samp></dt>
<dd><p>The maximum compensation in samples per second. Only relevant with compensate=1.
The default value is 500.
</p>
</dd>
<dt><samp>first_pts</samp></dt>
<dd><p>Assume that the first PTS should be this value. The time base is 1 / sample
rate. This allows for padding/trimming at the start of the stream. By default,
no assumption is made about the first frame’s expected PTS, so no padding or
trimming is done. For example, this could be set to 0 to pad the beginning with
silence if an audio stream starts after the video stream or to trim any samples
with a negative PTS due to encoder delay.
</p>
</dd>
</dl>
<a name="atempo"></a>
<h3 class="section">34.20 atempo<span class="pull-right"><a class="anchor hidden-xs" href="#atempo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-atempo" aria-hidden="true">TOC</a></span></h3>
<p>Adjust audio tempo.
</p>
<p>The filter accepts exactly one parameter, the audio tempo. If not
specified then the filter will assume nominal 1.0 tempo. Tempo must
be in the [0.5, 2.0] range.
</p>
<a name="Examples-38"></a>
<h4 class="subsection">34.20.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-38" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-38" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Slow down audio to 80% tempo:
<div class="example">
<pre class="example">atempo=0.8
</pre></div>
</li><li> To speed up audio to 125% tempo:
<div class="example">
<pre class="example">atempo=1.25
</pre></div>
</li></ul>
<a name="atrim"></a>
<h3 class="section">34.21 atrim<span class="pull-right"><a class="anchor hidden-xs" href="#atrim" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-atrim" aria-hidden="true">TOC</a></span></h3>
<p>Trim the input so that the output contains one continuous subpart of the input.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>start</samp></dt>
<dd><p>Timestamp (in seconds) of the start of the section to keep. I.e. the audio
sample with the timestamp <var>start</var> will be the first sample in the output.
</p>
</dd>
<dt><samp>end</samp></dt>
<dd><p>Specify time of the first audio sample that will be dropped, i.e. the
audio sample immediately preceding the one with the timestamp <var>end</var> will be
the last sample in the output.
</p>
</dd>
<dt><samp>start_pts</samp></dt>
<dd><p>Same as <var>start</var>, except this option sets the start timestamp in samples
instead of seconds.
</p>
</dd>
<dt><samp>end_pts</samp></dt>
<dd><p>Same as <var>end</var>, except this option sets the end timestamp in samples instead
of seconds.
</p>
</dd>
<dt><samp>duration</samp></dt>
<dd><p>The maximum duration of the output in seconds.
</p>
</dd>
<dt><samp>start_sample</samp></dt>
<dd><p>The number of the first sample that should be output.
</p>
</dd>
<dt><samp>end_sample</samp></dt>
<dd><p>The number of the first sample that should be dropped.
</p></dd>
</dl>
<p><samp>start</samp>, <samp>end</samp>, and <samp>duration</samp> are expressed as time
duration specifications; see
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>.
</p>
<p>Note that the first two sets of the start/end options and the <samp>duration</samp>
option look at the frame timestamp, while the _sample options simply count the
samples that pass through the filter. So start/end_pts and start/end_sample will
give different results when the timestamps are wrong, inexact or do not start at
zero. Also note that this filter does not modify the timestamps. If you wish
to have the output timestamps start at zero, insert the asetpts filter after the
atrim filter.
</p>
<p>If multiple start or end options are set, this filter tries to be greedy and
keep all samples that match at least one of the specified constraints. To keep
only the part that matches all the constraints at once, chain multiple atrim
filters.
</p>
<p>The defaults are such that all the input is kept. So it is possible to set e.g.
just the end values to keep everything before the specified time.
</p>
<p>Examples:
</p><ul>
<li> Drop everything except the second minute of input:
<div class="example">
<pre class="example">ffmpeg -i INPUT -af atrim=60:120
</pre></div>
</li><li> Keep only the first 1000 samples:
<div class="example">
<pre class="example">ffmpeg -i INPUT -af atrim=end_sample=1000
</pre></div>
</li></ul>
<a name="bandpass"></a>
<h3 class="section">34.22 bandpass<span class="pull-right"><a class="anchor hidden-xs" href="#bandpass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bandpass" aria-hidden="true">TOC</a></span></h3>
<p>Apply a two-pole Butterworth band-pass filter with central
frequency <var>frequency</var>, and (3dB-point) band-width width.
The <var>csg</var> option selects a constant skirt gain (peak gain = Q)
instead of the default: constant 0dB peak gain.
The filter roll off at 6dB per octave (20dB per decade).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the filter’s central frequency. Default is <code>3000</code>.
</p>
</dd>
<dt><samp>csg</samp></dt>
<dd><p>Constant skirt gain if set to 1. Defaults to 0.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
</p></dd>
</dl>
<a name="bandreject"></a>
<h3 class="section">34.23 bandreject<span class="pull-right"><a class="anchor hidden-xs" href="#bandreject" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bandreject" aria-hidden="true">TOC</a></span></h3>
<p>Apply a two-pole Butterworth band-reject filter with central
frequency <var>frequency</var>, and (3dB-point) band-width <var>width</var>.
The filter roll off at 6dB per octave (20dB per decade).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the filter’s central frequency. Default is <code>3000</code>.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
</p></dd>
</dl>
<a name="bass"></a>
<h3 class="section">34.24 bass<span class="pull-right"><a class="anchor hidden-xs" href="#bass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bass" aria-hidden="true">TOC</a></span></h3>
<p>Boost or cut the bass (lower) frequencies of the audio using a two-pole
shelving filter with a response similar to that of a standard
hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>gain, g</samp></dt>
<dd><p>Give the gain at 0 Hz. Its useful range is about -20
(for a large cut) to +20 (for a large boost).
Beware of clipping when using a positive gain.
</p>
</dd>
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the filter’s central frequency and so can be used
to extend or reduce the frequency range to be boosted or cut.
The default value is <code>100</code> Hz.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Determine how steep is the filter’s shelf transition.
</p></dd>
</dl>
<a name="biquad"></a>
<h3 class="section">34.25 biquad<span class="pull-right"><a class="anchor hidden-xs" href="#biquad" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-biquad" aria-hidden="true">TOC</a></span></h3>
<p>Apply a biquad IIR filter with the given coefficients.
Where <var>b0</var>, <var>b1</var>, <var>b2</var> and <var>a0</var>, <var>a1</var>, <var>a2</var>
are the numerator and denominator coefficients respectively.
</p>
<a name="bs2b"></a>
<h3 class="section">34.26 bs2b<span class="pull-right"><a class="anchor hidden-xs" href="#bs2b" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bs2b" aria-hidden="true">TOC</a></span></h3>
<p>Bauer stereo to binaural transformation, which improves headphone listening of
stereo audio records.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>profile</samp></dt>
<dd><p>Pre-defined crossfeed level.
</p><dl compact="compact">
<dt><samp>default</samp></dt>
<dd><p>Default level (fcut=700, feed=50).
</p>
</dd>
<dt><samp>cmoy</samp></dt>
<dd><p>Chu Moy circuit (fcut=700, feed=60).
</p>
</dd>
<dt><samp>jmeier</samp></dt>
<dd><p>Jan Meier circuit (fcut=650, feed=95).
</p>
</dd>
</dl>
</dd>
<dt><samp>fcut</samp></dt>
<dd><p>Cut frequency (in Hz).
</p>
</dd>
<dt><samp>feed</samp></dt>
<dd><p>Feed level (in Hz).
</p>
</dd>
</dl>
<a name="channelmap"></a>
<h3 class="section">34.27 channelmap<span class="pull-right"><a class="anchor hidden-xs" href="#channelmap" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-channelmap" aria-hidden="true">TOC</a></span></h3>
<p>Remap input channels to new locations.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>channel_layout</samp></dt>
<dd><p>The channel layout of the output stream.
</p>
</dd>
<dt><samp>map</samp></dt>
<dd><p>Map channels from input to output. The argument is a ’|’-separated list of
mappings, each in the <code><var>in_channel</var>-<var>out_channel</var></code> or
<var>in_channel</var> form. <var>in_channel</var> can be either the name of the input
channel (e.g. FL for front left) or its index in the input channel layout.
<var>out_channel</var> is the name of the output channel or its index in the output
channel layout. If <var>out_channel</var> is not given then it is implicitly an
index, starting with zero and increasing by one for each mapping.
</p></dd>
</dl>
<p>If no mapping is present, the filter will implicitly map input channels to
output channels, preserving indices.
</p>
<p>For example, assuming a 5.1+downmix input MOV file,
</p><div class="example">
<pre class="example">ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
</pre></div>
<p>will create an output WAV file tagged as stereo from the downmix channels of
the input.
</p>
<p>To fix a 5.1 WAV improperly encoded in AAC’s native channel order
</p><div class="example">
<pre class="example">ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
</pre></div>
<a name="channelsplit"></a>
<h3 class="section">34.28 channelsplit<span class="pull-right"><a class="anchor hidden-xs" href="#channelsplit" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-channelsplit" aria-hidden="true">TOC</a></span></h3>
<p>Split each channel from an input audio stream into a separate output stream.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>channel_layout</samp></dt>
<dd><p>The channel layout of the input stream. The default is "stereo".
</p></dd>
</dl>
<p>For example, assuming a stereo input MP3 file,
</p><div class="example">
<pre class="example">ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
</pre></div>
<p>will create an output Matroska file with two audio streams, one containing only
the left channel and the other the right channel.
</p>
<p>Split a 5.1 WAV file into per-channel files:
</p><div class="example">
<pre class="example">ffmpeg -i in.wav -filter_complex
'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
side_right.wav
</pre></div>
<a name="chorus"></a>
<h3 class="section">34.29 chorus<span class="pull-right"><a class="anchor hidden-xs" href="#chorus" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-chorus" aria-hidden="true">TOC</a></span></h3>
<p>Add a chorus effect to the audio.
</p>
<p>Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
</p>
<p>Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
constant, with chorus, it is varied using using sinusoidal or triangular modulation.
The modulation depth defines the range the modulated delay is played before or after
the delay. Hence the delayed sound will sound slower or faster, that is the delayed
sound tuned around the original one, like in a chorus where some vocals are slightly
off key.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>in_gain</samp></dt>
<dd><p>Set input gain. Default is 0.4.
</p>
</dd>
<dt><samp>out_gain</samp></dt>
<dd><p>Set output gain. Default is 0.4.
</p>
</dd>
<dt><samp>delays</samp></dt>
<dd><p>Set delays. A typical delay is around 40ms to 60ms.
</p>
</dd>
<dt><samp>decays</samp></dt>
<dd><p>Set decays.
</p>
</dd>
<dt><samp>speeds</samp></dt>
<dd><p>Set speeds.
</p>
</dd>
<dt><samp>depths</samp></dt>
<dd><p>Set depths.
</p></dd>
</dl>
<a name="Examples-39"></a>
<h4 class="subsection">34.29.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-39" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-39" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> A single delay:
<div class="example">
<pre class="example">chorus=0.7:0.9:55:0.4:0.25:2
</pre></div>
</li><li> Two delays:
<div class="example">
<pre class="example">chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
</pre></div>
</li><li> Fuller sounding chorus with three delays:
<div class="example">
<pre class="example">chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3
</pre></div>
</li></ul>
<a name="compand"></a>
<h3 class="section">34.30 compand<span class="pull-right"><a class="anchor hidden-xs" href="#compand" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-compand" aria-hidden="true">TOC</a></span></h3>
<p>Compress or expand the audio’s dynamic range.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>attacks</samp></dt>
<dt><samp>decays</samp></dt>
<dd><p>A list of times in seconds for each channel over which the instantaneous level
of the input signal is averaged to determine its volume. <var>attacks</var> refers to
increase of volume and <var>decays</var> refers to decrease of volume. For most
situations, the attack time (response to the audio getting louder) should be
shorter than the decay time, because the human ear is more sensitive to sudden
loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
a typical value for decay is 0.8 seconds.
If specified number of attacks & decays is lower than number of channels, the last
set attack/decay will be used for all remaining channels.
</p>
</dd>
<dt><samp>points</samp></dt>
<dd><p>A list of points for the transfer function, specified in dB relative to the
maximum possible signal amplitude. Each key points list must be defined using
the following syntax: <code>x0/y0|x1/y1|x2/y2|....</code> or
<code>x0/y0 x1/y1 x2/y2 ....</code>
</p>
<p>The input values must be in strictly increasing order but the transfer function
does not have to be monotonically rising. The point <code>0/0</code> is assumed but
may be overridden (by <code>0/out-dBn</code>). Typical values for the transfer
function are <code>-70/-70|-60/-20</code>.
</p>
</dd>
<dt><samp>soft-knee</samp></dt>
<dd><p>Set the curve radius in dB for all joints. It defaults to 0.01.
</p>
</dd>
<dt><samp>gain</samp></dt>
<dd><p>Set the additional gain in dB to be applied at all points on the transfer
function. This allows for easy adjustment of the overall gain.
It defaults to 0.
</p>
</dd>
<dt><samp>volume</samp></dt>
<dd><p>Set an initial volume, in dB, to be assumed for each channel when filtering
starts. This permits the user to supply a nominal level initially, so that, for
example, a very large gain is not applied to initial signal levels before the
companding has begun to operate. A typical value for audio which is initially
quiet is -90 dB. It defaults to 0.
</p>
</dd>
<dt><samp>delay</samp></dt>
<dd><p>Set a delay, in seconds. The input audio is analyzed immediately, but audio is
delayed before being fed to the volume adjuster. Specifying a delay
approximately equal to the attack/decay times allows the filter to effectively
operate in predictive rather than reactive mode. It defaults to 0.
</p>
</dd>
</dl>
<a name="Examples-40"></a>
<h4 class="subsection">34.30.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-40" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-40" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Make music with both quiet and loud passages suitable for listening to in a
noisy environment:
<div class="example">
<pre class="example">compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
</pre></div>
<p>Another example for audio with whisper and explosion parts:
</p><div class="example">
<pre class="example">compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
</pre></div>
</li><li> A noise gate for when the noise is at a lower level than the signal:
<div class="example">
<pre class="example">compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
</pre></div>
</li><li> Here is another noise gate, this time for when the noise is at a higher level
than the signal (making it, in some ways, similar to squelch):
<div class="example">
<pre class="example">compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
</pre></div>
</li></ul>
<a name="dcshift"></a>
<h3 class="section">34.31 dcshift<span class="pull-right"><a class="anchor hidden-xs" href="#dcshift" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dcshift" aria-hidden="true">TOC</a></span></h3>
<p>Apply a DC shift to the audio.
</p>
<p>This can be useful to remove a DC offset (caused perhaps by a hardware problem
in the recording chain) from the audio. The effect of a DC offset is reduced
headroom and hence volume. The <a href="#astats">astats</a> filter can be used to determine if
a signal has a DC offset.
</p>
<dl compact="compact">
<dt><samp>shift</samp></dt>
<dd><p>Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift
the audio.
</p>
</dd>
<dt><samp>limitergain</samp></dt>
<dd><p>Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is
used to prevent clipping.
</p></dd>
</dl>
<a name="dynaudnorm"></a>
<h3 class="section">34.32 dynaudnorm<span class="pull-right"><a class="anchor hidden-xs" href="#dynaudnorm" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dynaudnorm" aria-hidden="true">TOC</a></span></h3>
<p>Dynamic Audio Normalizer.
</p>
<p>This filter applies a certain amount of gain to the input audio in order
to bring its peak magnitude to a target level (e.g. 0 dBFS). However, in
contrast to more "simple" normalization algorithms, the Dynamic Audio
Normalizer *dynamically* re-adjusts the gain factor to the input audio.
This allows for applying extra gain to the "quiet" sections of the audio
while avoiding distortions or clipping the "loud" sections. In other words:
The Dynamic Audio Normalizer will "even out" the volume of quiet and loud
sections, in the sense that the volume of each section is brought to the
same target level. Note, however, that the Dynamic Audio Normalizer achieves
this goal *without* applying "dynamic range compressing". It will retain 100%
of the dynamic range *within* each section of the audio file.
</p>
<dl compact="compact">
<dt><samp>f</samp></dt>
<dd><p>Set the frame length in milliseconds. In range from 10 to 8000 milliseconds.
Default is 500 milliseconds.
The Dynamic Audio Normalizer processes the input audio in small chunks,
referred to as frames. This is required, because a peak magnitude has no
meaning for just a single sample value. Instead, we need to determine the
peak magnitude for a contiguous sequence of sample values. While a "standard"
normalizer would simply use the peak magnitude of the complete file, the
Dynamic Audio Normalizer determines the peak magnitude individually for each
frame. The length of a frame is specified in milliseconds. By default, the
Dynamic Audio Normalizer uses a frame length of 500 milliseconds, which has
been found to give good results with most files.
Note that the exact frame length, in number of samples, will be determined
automatically, based on the sampling rate of the individual input audio file.
</p>
</dd>
<dt><samp>g</samp></dt>
<dd><p>Set the Gaussian filter window size. In range from 3 to 301, must be odd
number. Default is 31.
Probably the most important parameter of the Dynamic Audio Normalizer is the
<code>window size</code> of the Gaussian smoothing filter. The filter’s window size
is specified in frames, centered around the current frame. For the sake of
simplicity, this must be an odd number. Consequently, the default value of 31
takes into account the current frame, as well as the 15 preceding frames and
the 15 subsequent frames. Using a larger window results in a stronger
smoothing effect and thus in less gain variation, i.e. slower gain
adaptation. Conversely, using a smaller window results in a weaker smoothing
effect and thus in more gain variation, i.e. faster gain adaptation.
In other words, the more you increase this value, the more the Dynamic Audio
Normalizer will behave like a "traditional" normalization filter. On the
contrary, the more you decrease this value, the more the Dynamic Audio
Normalizer will behave like a dynamic range compressor.
</p>
</dd>
<dt><samp>p</samp></dt>
<dd><p>Set the target peak value. This specifies the highest permissible magnitude
level for the normalized audio input. This filter will try to approach the
target peak magnitude as closely as possible, but at the same time it also
makes sure that the normalized signal will never exceed the peak magnitude.
A frame’s maximum local gain factor is imposed directly by the target peak
magnitude. The default value is 0.95 and thus leaves a headroom of 5%*.
It is not recommended to go above this value.
</p>
</dd>
<dt><samp>m</samp></dt>
<dd><p>Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0.
The Dynamic Audio Normalizer determines the maximum possible (local) gain
factor for each input frame, i.e. the maximum gain factor that does not
result in clipping or distortion. The maximum gain factor is determined by
the frame’s highest magnitude sample. However, the Dynamic Audio Normalizer
additionally bounds the frame’s maximum gain factor by a predetermined
(global) maximum gain factor. This is done in order to avoid excessive gain
factors in "silent" or almost silent frames. By default, the maximum gain
factor is 10.0, For most inputs the default value should be sufficient and
it usually is not recommended to increase this value. Though, for input
with an extremely low overall volume level, it may be necessary to allow even
higher gain factors. Note, however, that the Dynamic Audio Normalizer does
not simply apply a "hard" threshold (i.e. cut off values above the threshold).
Instead, a "sigmoid" threshold function will be applied. This way, the
gain factors will smoothly approach the threshold value, but never exceed that
value.
</p>
</dd>
<dt><samp>r</samp></dt>
<dd><p>Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled.
By default, the Dynamic Audio Normalizer performs "peak" normalization.
This means that the maximum local gain factor for each frame is defined
(only) by the frame’s highest magnitude sample. This way, the samples can
be amplified as much as possible without exceeding the maximum signal
level, i.e. without clipping. Optionally, however, the Dynamic Audio
Normalizer can also take into account the frame’s root mean square,
abbreviated RMS. In electrical engineering, the RMS is commonly used to
determine the power of a time-varying signal. It is therefore considered
that the RMS is a better approximation of the "perceived loudness" than
just looking at the signal’s peak magnitude. Consequently, by adjusting all
frames to a constant RMS value, a uniform "perceived loudness" can be
established. If a target RMS value has been specified, a frame’s local gain
factor is defined as the factor that would result in exactly that RMS value.
Note, however, that the maximum local gain factor is still restricted by the
frame’s highest magnitude sample, in order to prevent clipping.
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>Enable channels coupling. By default is enabled.
By default, the Dynamic Audio Normalizer will amplify all channels by the same
amount. This means the same gain factor will be applied to all channels, i.e.
the maximum possible gain factor is determined by the "loudest" channel.
However, in some recordings, it may happen that the volume of the different
channels is uneven, e.g. one channel may be "quieter" than the other one(s).
In this case, this option can be used to disable the channel coupling. This way,
the gain factor will be determined independently for each channel, depending
only on the individual channel’s highest magnitude sample. This allows for
harmonizing the volume of the different channels.
</p>
</dd>
<dt><samp>c</samp></dt>
<dd><p>Enable DC bias correction. By default is disabled.
An audio signal (in the time domain) is a sequence of sample values.
In the Dynamic Audio Normalizer these sample values are represented in the
-1.0 to 1.0 range, regardless of the original input format. Normally, the
audio signal, or "waveform", should be centered around the zero point.
That means if we calculate the mean value of all samples in a file, or in a
single frame, then the result should be 0.0 or at least very close to that
value. If, however, there is a significant deviation of the mean value from
0.0, in either positive or negative direction, this is referred to as a
DC bias or DC offset. Since a DC bias is clearly undesirable, the Dynamic
Audio Normalizer provides optional DC bias correction.
With DC bias correction enabled, the Dynamic Audio Normalizer will determine
the mean value, or "DC correction" offset, of each input frame and subtract
that value from all of the frame’s sample values which ensures those samples
are centered around 0.0 again. Also, in order to avoid "gaps" at the frame
boundaries, the DC correction offset values will be interpolated smoothly
between neighbouring frames.
</p>
</dd>
<dt><samp>b</samp></dt>
<dd><p>Enable alternative boundary mode. By default is disabled.
The Dynamic Audio Normalizer takes into account a certain neighbourhood
around each frame. This includes the preceding frames as well as the
subsequent frames. However, for the "boundary" frames, located at the very
beginning and at the very end of the audio file, not all neighbouring
frames are available. In particular, for the first few frames in the audio
file, the preceding frames are not known. And, similarly, for the last few
frames in the audio file, the subsequent frames are not known. Thus, the
question arises which gain factors should be assumed for the missing frames
in the "boundary" region. The Dynamic Audio Normalizer implements two modes
to deal with this situation. The default boundary mode assumes a gain factor
of exactly 1.0 for the missing frames, resulting in a smooth "fade in" and
"fade out" at the beginning and at the end of the input, respectively.
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
By default, the Dynamic Audio Normalizer does not apply "traditional"
compression. This means that signal peaks will not be pruned and thus the
full dynamic range will be retained within each local neighbourhood. However,
in some cases it may be desirable to combine the Dynamic Audio Normalizer’s
normalization algorithm with a more "traditional" compression.
For this purpose, the Dynamic Audio Normalizer provides an optional compression
(thresholding) function. If (and only if) the compression feature is enabled,
all input frames will be processed by a soft knee thresholding function prior
to the actual normalization process. Put simply, the thresholding function is
going to prune all samples whose magnitude exceeds a certain threshold value.
However, the Dynamic Audio Normalizer does not simply apply a fixed threshold
value. Instead, the threshold value will be adjusted for each individual
frame.
In general, smaller parameters result in stronger compression, and vice versa.
Values below 3.0 are not recommended, because audible distortion may appear.
</p></dd>
</dl>
<a name="earwax"></a>
<h3 class="section">34.33 earwax<span class="pull-right"><a class="anchor hidden-xs" href="#earwax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-earwax" aria-hidden="true">TOC</a></span></h3>
<p>Make audio easier to listen to on headphones.
</p>
<p>This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
so that when listened to on headphones the stereo image is moved from
inside your head (standard for headphones) to outside and in front of
the listener (standard for speakers).
</p>
<p>Ported from SoX.
</p>
<a name="equalizer"></a>
<h3 class="section">34.34 equalizer<span class="pull-right"><a class="anchor hidden-xs" href="#equalizer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-equalizer" aria-hidden="true">TOC</a></span></h3>
<p>Apply a two-pole peaking equalisation (EQ) filter. With this
filter, the signal-level at and around a selected frequency can
be increased or decreased, whilst (unlike bandpass and bandreject
filters) that at all other frequencies is unchanged.
</p>
<p>In order to produce complex equalisation curves, this filter can
be given several times, each with a different central frequency.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the filter’s central frequency in Hz.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
</p>
</dd>
<dt><samp>gain, g</samp></dt>
<dd><p>Set the required gain or attenuation in dB.
Beware of clipping when using a positive gain.
</p></dd>
</dl>
<a name="Examples-41"></a>
<h4 class="subsection">34.34.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-41" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-41" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
<div class="example">
<pre class="example">equalizer=f=1000:width_type=h:width=200:g=-10
</pre></div>
</li><li> Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
<div class="example">
<pre class="example">equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
</pre></div>
</li></ul>
<a name="flanger"></a>
<h3 class="section">34.35 flanger<span class="pull-right"><a class="anchor hidden-xs" href="#flanger" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-flanger" aria-hidden="true">TOC</a></span></h3>
<p>Apply a flanging effect to the audio.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>delay</samp></dt>
<dd><p>Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
</p>
</dd>
<dt><samp>depth</samp></dt>
<dd><p>Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
</p>
</dd>
<dt><samp>regen</samp></dt>
<dd><p>Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
Default value is 0.
</p>
</dd>
<dt><samp>width</samp></dt>
<dd><p>Set percentage of delayed signal mixed with original. Range from 0 to 100.
Default value is 71.
</p>
</dd>
<dt><samp>speed</samp></dt>
<dd><p>Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
</p>
</dd>
<dt><samp>shape</samp></dt>
<dd><p>Set swept wave shape, can be <var>triangular</var> or <var>sinusoidal</var>.
Default value is <var>sinusoidal</var>.
</p>
</dd>
<dt><samp>phase</samp></dt>
<dd><p>Set swept wave percentage-shift for multi channel. Range from 0 to 100.
Default value is 25.
</p>
</dd>
<dt><samp>interp</samp></dt>
<dd><p>Set delay-line interpolation, <var>linear</var> or <var>quadratic</var>.
Default is <var>linear</var>.
</p></dd>
</dl>
<a name="highpass"></a>
<h3 class="section">34.36 highpass<span class="pull-right"><a class="anchor hidden-xs" href="#highpass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-highpass" aria-hidden="true">TOC</a></span></h3>
<p>Apply a high-pass filter with 3dB point frequency.
The filter can be either single-pole, or double-pole (the default).
The filter roll off at 6dB per pole per octave (20dB per pole per decade).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set frequency in Hz. Default is 3000.
</p>
</dd>
<dt><samp>poles, p</samp></dt>
<dd><p>Set number of poles. Default is 2.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
Applies only to double-pole filter.
The default is 0.707q and gives a Butterworth response.
</p></dd>
</dl>
<a name="join"></a>
<h3 class="section">34.37 join<span class="pull-right"><a class="anchor hidden-xs" href="#join" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-join" aria-hidden="true">TOC</a></span></h3>
<p>Join multiple input streams into one multi-channel stream.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>inputs</samp></dt>
<dd><p>The number of input streams. It defaults to 2.
</p>
</dd>
<dt><samp>channel_layout</samp></dt>
<dd><p>The desired output channel layout. It defaults to stereo.
</p>
</dd>
<dt><samp>map</samp></dt>
<dd><p>Map channels from inputs to output. The argument is a ’|’-separated list of
mappings, each in the <code><var>input_idx</var>.<var>in_channel</var>-<var>out_channel</var></code>
form. <var>input_idx</var> is the 0-based index of the input stream. <var>in_channel</var>
can be either the name of the input channel (e.g. FL for front left) or its
index in the specified input stream. <var>out_channel</var> is the name of the output
channel.
</p></dd>
</dl>
<p>The filter will attempt to guess the mappings when they are not specified
explicitly. It does so by first trying to find an unused matching input channel
and if that fails it picks the first unused input channel.
</p>
<p>Join 3 inputs (with properly set channel layouts):
</p><div class="example">
<pre class="example">ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
</pre></div>
<p>Build a 5.1 output from 6 single-channel streams:
</p><div class="example">
<pre class="example">ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
out
</pre></div>
<a name="ladspa"></a>
<h3 class="section">34.38 ladspa<span class="pull-right"><a class="anchor hidden-xs" href="#ladspa" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ladspa" aria-hidden="true">TOC</a></span></h3>
<p>Load a LADSPA (Linux Audio Developer’s Simple Plugin API) plugin.
</p>
<p>To enable compilation of this filter you need to configure FFmpeg with
<code>--enable-ladspa</code>.
</p>
<dl compact="compact">
<dt><samp>file, f</samp></dt>
<dd><p>Specifies the name of LADSPA plugin library to load. If the environment
variable <code>LADSPA_PATH</code> is defined, the LADSPA plugin is searched in
each one of the directories specified by the colon separated list in
<code>LADSPA_PATH</code>, otherwise in the standard LADSPA paths, which are in
this order: <samp>HOME/.ladspa/lib/</samp>, <samp>/usr/local/lib/ladspa/</samp>,
<samp>/usr/lib/ladspa/</samp>.
</p>
</dd>
<dt><samp>plugin, p</samp></dt>
<dd><p>Specifies the plugin within the library. Some libraries contain only
one plugin, but others contain many of them. If this is not set filter
will list all available plugins within the specified library.
</p>
</dd>
<dt><samp>controls, c</samp></dt>
<dd><p>Set the ’|’ separated list of controls which are zero or more floating point
values that determine the behavior of the loaded plugin (for example delay,
threshold or gain).
Controls need to be defined using the following syntax:
c0=<var>value0</var>|c1=<var>value1</var>|c2=<var>value2</var>|..., where
<var>valuei</var> is the value set on the <var>i</var>-th control.
If <samp>controls</samp> is set to <code>help</code>, all available controls and
their valid ranges are printed.
</p>
</dd>
<dt><samp>sample_rate, s</samp></dt>
<dd><p>Specify the sample rate, default to 44100. Only used if plugin have
zero inputs.
</p>
</dd>
<dt><samp>nb_samples, n</samp></dt>
<dd><p>Set the number of samples per channel per each output frame, default
is 1024. Only used if plugin have zero inputs.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Set the minimum duration of the sourced audio. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
Note that the resulting duration may be greater than the specified duration,
as the generated audio is always cut at the end of a complete frame.
If not specified, or the expressed duration is negative, the audio is
supposed to be generated forever.
Only used if plugin have zero inputs.
</p>
</dd>
</dl>
<a name="Examples-42"></a>
<h4 class="subsection">34.38.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-42" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-42" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> List all available plugins within amp (LADSPA example plugin) library:
<div class="example">
<pre class="example">ladspa=file=amp
</pre></div>
</li><li> List all available controls and their valid ranges for <code>vcf_notch</code>
plugin from <code>VCF</code> library:
<div class="example">
<pre class="example">ladspa=f=vcf:p=vcf_notch:c=help
</pre></div>
</li><li> Simulate low quality audio equipment using <code>Computer Music Toolkit</code> (CMT)
plugin library:
<div class="example">
<pre class="example">ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
</pre></div>
</li><li> Add reverberation to the audio using TAP-plugins
(Tom’s Audio Processing plugins):
<div class="example">
<pre class="example">ladspa=file=tap_reverb:tap_reverb
</pre></div>
</li><li> Generate white noise, with 0.2 amplitude:
<div class="example">
<pre class="example">ladspa=file=cmt:noise_source_white:c=c0=.2
</pre></div>
</li><li> Generate 20 bpm clicks using plugin <code>C* Click - Metronome</code> from the
<code>C* Audio Plugin Suite</code> (CAPS) library:
<div class="example">
<pre class="example">ladspa=file=caps:Click:c=c1=20'
</pre></div>
</li><li> Apply <code>C* Eq10X2 - Stereo 10-band equaliser</code> effect:
<div class="example">
<pre class="example">ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
</pre></div>
</li></ul>
<a name="Commands"></a>
<h4 class="subsection">34.38.2 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>cN</samp></dt>
<dd><p>Modify the <var>N</var>-th control value.
</p>
<p>If the specified value is not valid, it is ignored and prior one is kept.
</p></dd>
</dl>
<a name="lowpass"></a>
<h3 class="section">34.39 lowpass<span class="pull-right"><a class="anchor hidden-xs" href="#lowpass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-lowpass" aria-hidden="true">TOC</a></span></h3>
<p>Apply a low-pass filter with 3dB point frequency.
The filter can be either single-pole or double-pole (the default).
The filter roll off at 6dB per pole per octave (20dB per pole per decade).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set frequency in Hz. Default is 500.
</p>
</dd>
<dt><samp>poles, p</samp></dt>
<dd><p>Set number of poles. Default is 2.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Specify the band-width of a filter in width_type units.
Applies only to double-pole filter.
The default is 0.707q and gives a Butterworth response.
</p></dd>
</dl>
<a name="pan"></a><a name="pan-1"></a>
<h3 class="section">34.40 pan<span class="pull-right"><a class="anchor hidden-xs" href="#pan-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pan-1" aria-hidden="true">TOC</a></span></h3>
<p>Mix channels with specific gain levels. The filter accepts the output
channel layout followed by a set of channels definitions.
</p>
<p>This filter is also designed to efficiently remap the channels of an audio
stream.
</p>
<p>The filter accepts parameters of the form:
"<var>l</var>|<var>outdef</var>|<var>outdef</var>|..."
</p>
<dl compact="compact">
<dt><samp>l</samp></dt>
<dd><p>output channel layout or number of channels
</p>
</dd>
<dt><samp>outdef</samp></dt>
<dd><p>output channel specification, of the form:
"<var>out_name</var>=[<var>gain</var>*]<var>in_name</var>[+[<var>gain</var>*]<var>in_name</var>...]"
</p>
</dd>
<dt><samp>out_name</samp></dt>
<dd><p>output channel to define, either a channel name (FL, FR, etc.) or a channel
number (c0, c1, etc.)
</p>
</dd>
<dt><samp>gain</samp></dt>
<dd><p>multiplicative coefficient for the channel, 1 leaving the volume unchanged
</p>
</dd>
<dt><samp>in_name</samp></dt>
<dd><p>input channel to use, see out_name for details; it is not possible to mix
named and numbered input channels
</p></dd>
</dl>
<p>If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
that specification will be renormalized so that the total is 1, thus
avoiding clipping noise.
</p>
<a name="Mixing-examples"></a>
<h4 class="subsection">34.40.1 Mixing examples<span class="pull-right"><a class="anchor hidden-xs" href="#Mixing-examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Mixing-examples" aria-hidden="true">TOC</a></span></h4>
<p>For example, if you want to down-mix from stereo to mono, but with a bigger
factor for the left channel:
</p><div class="example">
<pre class="example">pan=1c|c0=0.9*c0+0.1*c1
</pre></div>
<p>A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
7-channels surround:
</p><div class="example">
<pre class="example">pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
</pre></div>
<p>Note that <code>ffmpeg</code> integrates a default down-mix (and up-mix) system
that should be preferred (see "-ac" option) unless you have very specific
needs.
</p>
<a name="Remapping-examples"></a>
<h4 class="subsection">34.40.2 Remapping examples<span class="pull-right"><a class="anchor hidden-xs" href="#Remapping-examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Remapping-examples" aria-hidden="true">TOC</a></span></h4>
<p>The channel remapping will be effective if, and only if:
</p>
<ul>
<li> gain coefficients are zeroes or ones,
</li><li> only one input per channel output,
</li></ul>
<p>If all these conditions are satisfied, the filter will notify the user ("Pure
channel mapping detected"), and use an optimized and lossless method to do the
remapping.
</p>
<p>For example, if you have a 5.1 source and want a stereo audio stream by
dropping the extra channels:
</p><div class="example">
<pre class="example">pan="stereo| c0=FL | c1=FR"
</pre></div>
<p>Given the same source, you can also switch front left and front right channels
and keep the input channel layout:
</p><div class="example">
<pre class="example">pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
</pre></div>
<p>If the input is a stereo audio stream, you can mute the front left channel (and
still keep the stereo channel layout) with:
</p><div class="example">
<pre class="example">pan="stereo|c1=c1"
</pre></div>
<p>Still with a stereo audio stream input, you can copy the right channel in both
front left and right:
</p><div class="example">
<pre class="example">pan="stereo| c0=FR | c1=FR"
</pre></div>
<a name="replaygain"></a>
<h3 class="section">34.41 replaygain<span class="pull-right"><a class="anchor hidden-xs" href="#replaygain" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-replaygain" aria-hidden="true">TOC</a></span></h3>
<p>ReplayGain scanner filter. This filter takes an audio stream as an input and
outputs it unchanged.
At end of filtering it displays <code>track_gain</code> and <code>track_peak</code>.
</p>
<a name="resample"></a>
<h3 class="section">34.42 resample<span class="pull-right"><a class="anchor hidden-xs" href="#resample" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-resample" aria-hidden="true">TOC</a></span></h3>
<p>Convert the audio sample format, sample rate and channel layout. It is
not meant to be used directly.
</p>
<a name="sidechaincompress"></a>
<h3 class="section">34.43 sidechaincompress<span class="pull-right"><a class="anchor hidden-xs" href="#sidechaincompress" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sidechaincompress" aria-hidden="true">TOC</a></span></h3>
<p>This filter acts like normal compressor but has the ability to compress
detected signal using second input signal.
It needs two input streams and returns one output stream.
First input stream will be processed depending on second stream signal.
The filtered signal then can be filtered with other filters in later stages of
processing. See <a href="#pan">pan</a> and <a href="#amerge">amerge</a> filter.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>threshold</samp></dt>
<dd><p>If a signal of second stream raises above this level it will affect the gain
reduction of first stream.
By default is 0.125. Range is between 0.00097563 and 1.
</p>
</dd>
<dt><samp>ratio</samp></dt>
<dd><p>Set a ratio about which the signal is reduced. 1:2 means that if the level
raised 4dB above the threshold, it will be only 2dB above after the reduction.
Default is 2. Range is between 1 and 20.
</p>
</dd>
<dt><samp>attack</samp></dt>
<dd><p>Amount of milliseconds the signal has to rise above the threshold before gain
reduction starts. Default is 20. Range is between 0.01 and 2000.
</p>
</dd>
<dt><samp>release</samp></dt>
<dd><p>Amount of milliseconds the signal has to fall below the threshold before
reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
</p>
</dd>
<dt><samp>makeup</samp></dt>
<dd><p>Set the amount by how much signal will be amplified after processing.
Default is 2. Range is from 1 and 64.
</p>
</dd>
<dt><samp>knee</samp></dt>
<dd><p>Curve the sharp knee around the threshold to enter gain reduction more softly.
Default is 2.82843. Range is between 1 and 8.
</p>
</dd>
<dt><samp>link</samp></dt>
<dd><p>Choose if the <code>average</code> level between all channels of side-chain stream
or the louder(<code>maximum</code>) channel of side-chain stream affects the
reduction. Default is <code>average</code>.
</p>
</dd>
<dt><samp>detection</samp></dt>
<dd><p>Should the exact signal be taken in case of <code>peak</code> or an RMS one in case
of <code>rms</code>. Default is <code>rms</code> which is mainly smoother.
</p></dd>
</dl>
<a name="Examples-43"></a>
<h4 class="subsection">34.43.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-43" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-43" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
depending on the signal of 2nd input and later compressed signal to be
merged with 2nd input:
<div class="example">
<pre class="example">ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
</pre></div>
</li></ul>
<a name="silencedetect"></a>
<h3 class="section">34.44 silencedetect<span class="pull-right"><a class="anchor hidden-xs" href="#silencedetect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-silencedetect" aria-hidden="true">TOC</a></span></h3>
<p>Detect silence in an audio stream.
</p>
<p>This filter logs a message when it detects that the input audio volume is less
or equal to a noise tolerance value for a duration greater or equal to the
minimum detected noise duration.
</p>
<p>The printed times and duration are expressed in seconds.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>duration, d</samp></dt>
<dd><p>Set silence duration until notification (default is 2 seconds).
</p>
</dd>
<dt><samp>noise, n</samp></dt>
<dd><p>Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
specified value) or amplitude ratio. Default is -60dB, or 0.001.
</p></dd>
</dl>
<a name="Examples-44"></a>
<h4 class="subsection">34.44.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-44" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-44" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Detect 5 seconds of silence with -50dB noise tolerance:
<div class="example">
<pre class="example">silencedetect=n=-50dB:d=5
</pre></div>
</li><li> Complete example with <code>ffmpeg</code> to detect silence with 0.0001 noise
tolerance in <samp>silence.mp3</samp>:
<div class="example">
<pre class="example">ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
</pre></div>
</li></ul>
<a name="silenceremove"></a>
<h3 class="section">34.45 silenceremove<span class="pull-right"><a class="anchor hidden-xs" href="#silenceremove" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-silenceremove" aria-hidden="true">TOC</a></span></h3>
<p>Remove silence from the beginning, middle or end of the audio.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>start_periods</samp></dt>
<dd><p>This value is used to indicate if audio should be trimmed at beginning of
the audio. A value of zero indicates no silence should be trimmed from the
beginning. When specifying a non-zero value, it trims audio up until it
finds non-silence. Normally, when trimming silence from beginning of audio
the <var>start_periods</var> will be <code>1</code> but it can be increased to higher
values to trim all audio up to specific count of non-silence periods.
Default value is <code>0</code>.
</p>
</dd>
<dt><samp>start_duration</samp></dt>
<dd><p>Specify the amount of time that non-silence must be detected before it stops
trimming audio. By increasing the duration, bursts of noises can be treated
as silence and trimmed off. Default value is <code>0</code>.
</p>
</dd>
<dt><samp>start_threshold</samp></dt>
<dd><p>This indicates what sample value should be treated as silence. For digital
audio, a value of <code>0</code> may be fine but for audio recorded from analog,
you may wish to increase the value to account for background noise.
Can be specified in dB (in case "dB" is appended to the specified value)
or amplitude ratio. Default value is <code>0</code>.
</p>
</dd>
<dt><samp>stop_periods</samp></dt>
<dd><p>Set the count for trimming silence from the end of audio.
To remove silence from the middle of a file, specify a <var>stop_periods</var>
that is negative. This value is then treated as a positive value and is
used to indicate the effect should restart processing as specified by
<var>start_periods</var>, making it suitable for removing periods of silence
in the middle of the audio.
Default value is <code>0</code>.
</p>
</dd>
<dt><samp>stop_duration</samp></dt>
<dd><p>Specify a duration of silence that must exist before audio is not copied any
more. By specifying a higher duration, silence that is wanted can be left in
the audio.
Default value is <code>0</code>.
</p>
</dd>
<dt><samp>stop_threshold</samp></dt>
<dd><p>This is the same as <samp>start_threshold</samp> but for trimming silence from
the end of audio.
Can be specified in dB (in case "dB" is appended to the specified value)
or amplitude ratio. Default value is <code>0</code>.
</p>
</dd>
<dt><samp>leave_silence</samp></dt>
<dd><p>This indicate that <var>stop_duration</var> length of audio should be left intact
at the beginning of each period of silence.
For example, if you want to remove long pauses between words but do not want
to remove the pauses completely. Default value is <code>0</code>.
</p>
</dd>
</dl>
<a name="Examples-45"></a>
<h4 class="subsection">34.45.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-45" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-45" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> The following example shows how this filter can be used to start a recording
that does not contain the delay at the start which usually occurs between
pressing the record button and the start of the performance:
<div class="example">
<pre class="example">silenceremove=1:5:0.02
</pre></div>
</li></ul>
<a name="treble"></a>
<h3 class="section">34.46 treble<span class="pull-right"><a class="anchor hidden-xs" href="#treble" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-treble" aria-hidden="true">TOC</a></span></h3>
<p>Boost or cut treble (upper) frequencies of the audio using a two-pole
shelving filter with a response similar to that of a standard
hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>gain, g</samp></dt>
<dd><p>Give the gain at whichever is the lower of ~22 kHz and the
Nyquist frequency. Its useful range is about -20 (for a large cut)
to +20 (for a large boost). Beware of clipping when using a positive gain.
</p>
</dd>
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the filter’s central frequency and so can be used
to extend or reduce the frequency range to be boosted or cut.
The default value is <code>3000</code> Hz.
</p>
</dd>
<dt><samp>width_type</samp></dt>
<dd><p>Set method to specify band-width of filter.
</p><dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Hz
</p></dd>
<dt><samp>q</samp></dt>
<dd><p>Q-Factor
</p></dd>
<dt><samp>o</samp></dt>
<dd><p>octave
</p></dd>
<dt><samp>s</samp></dt>
<dd><p>slope
</p></dd>
</dl>
</dd>
<dt><samp>width, w</samp></dt>
<dd><p>Determine how steep is the filter’s shelf transition.
</p></dd>
</dl>
<a name="volume"></a>
<h3 class="section">34.47 volume<span class="pull-right"><a class="anchor hidden-xs" href="#volume" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-volume" aria-hidden="true">TOC</a></span></h3>
<p>Adjust the input audio volume.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>volume</samp></dt>
<dd><p>Set audio volume expression.
</p>
<p>Output values are clipped to the maximum value.
</p>
<p>The output audio volume is given by the relation:
</p><div class="example">
<pre class="example"><var>output_volume</var> = <var>volume</var> * <var>input_volume</var>
</pre></div>
<p>The default value for <var>volume</var> is "1.0".
</p>
</dd>
<dt><samp>precision</samp></dt>
<dd><p>This parameter represents the mathematical precision.
</p>
<p>It determines which input sample formats will be allowed, which affects the
precision of the volume scaling.
</p>
<dl compact="compact">
<dt><samp>fixed</samp></dt>
<dd><p>8-bit fixed-point; this limits input sample format to U8, S16, and S32.
</p></dd>
<dt><samp>float</samp></dt>
<dd><p>32-bit floating-point; this limits input sample format to FLT. (default)
</p></dd>
<dt><samp>double</samp></dt>
<dd><p>64-bit floating-point; this limits input sample format to DBL.
</p></dd>
</dl>
</dd>
<dt><samp>replaygain</samp></dt>
<dd><p>Choose the behaviour on encountering ReplayGain side data in input frames.
</p>
<dl compact="compact">
<dt><samp>drop</samp></dt>
<dd><p>Remove ReplayGain side data, ignoring its contents (the default).
</p>
</dd>
<dt><samp>ignore</samp></dt>
<dd><p>Ignore ReplayGain side data, but leave it in the frame.
</p>
</dd>
<dt><samp>track</samp></dt>
<dd><p>Prefer the track gain, if present.
</p>
</dd>
<dt><samp>album</samp></dt>
<dd><p>Prefer the album gain, if present.
</p></dd>
</dl>
</dd>
<dt><samp>replaygain_preamp</samp></dt>
<dd><p>Pre-amplification gain in dB to apply to the selected replaygain gain.
</p>
<p>Default value for <var>replaygain_preamp</var> is 0.0.
</p>
</dd>
<dt><samp>eval</samp></dt>
<dd><p>Set when the volume expression is evaluated.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>once</samp>’</dt>
<dd><p>only evaluate expression once during the filter initialization, or
when the ‘<samp>volume</samp>’ command is sent
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>evaluate expression for each incoming frame
</p></dd>
</dl>
<p>Default value is ‘<samp>once</samp>’.
</p></dd>
</dl>
<p>The volume expression can contain the following parameters.
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>frame number (starting at zero)
</p></dd>
<dt><samp>nb_channels</samp></dt>
<dd><p>number of channels
</p></dd>
<dt><samp>nb_consumed_samples</samp></dt>
<dd><p>number of samples consumed by the filter
</p></dd>
<dt><samp>nb_samples</samp></dt>
<dd><p>number of samples in the current frame
</p></dd>
<dt><samp>pos</samp></dt>
<dd><p>original frame position in the file
</p></dd>
<dt><samp>pts</samp></dt>
<dd><p>frame PTS
</p></dd>
<dt><samp>sample_rate</samp></dt>
<dd><p>sample rate
</p></dd>
<dt><samp>startpts</samp></dt>
<dd><p>PTS at start of stream
</p></dd>
<dt><samp>startt</samp></dt>
<dd><p>time at start of stream
</p></dd>
<dt><samp>t</samp></dt>
<dd><p>frame time
</p></dd>
<dt><samp>tb</samp></dt>
<dd><p>timestamp timebase
</p></dd>
<dt><samp>volume</samp></dt>
<dd><p>last set volume value
</p></dd>
</dl>
<p>Note that when <samp>eval</samp> is set to ‘<samp>once</samp>’ only the
<var>sample_rate</var> and <var>tb</var> variables are available, all other
variables will evaluate to NAN.
</p>
<a name="Commands-1"></a>
<h4 class="subsection">34.47.1 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-1" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>volume</samp></dt>
<dd><p>Modify the volume expression.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
<dt><samp>replaygain_noclip</samp></dt>
<dd><p>Prevent clipping by limiting the gain applied.
</p>
<p>Default value for <var>replaygain_noclip</var> is 1.
</p>
</dd>
</dl>
<a name="Examples-46"></a>
<h4 class="subsection">34.47.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-46" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-46" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Halve the input audio volume:
<div class="example">
<pre class="example">volume=volume=0.5
volume=volume=1/2
volume=volume=-6.0206dB
</pre></div>
<p>In all the above example the named key for <samp>volume</samp> can be
omitted, for example like in:
</p><div class="example">
<pre class="example">volume=0.5
</pre></div>
</li><li> Increase input audio power by 6 decibels using fixed-point precision:
<div class="example">
<pre class="example">volume=volume=6dB:precision=fixed
</pre></div>
</li><li> Fade volume after time 10 with an annihilation period of 5 seconds:
<div class="example">
<pre class="example">volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
</pre></div>
</li></ul>
<a name="volumedetect"></a>
<h3 class="section">34.48 volumedetect<span class="pull-right"><a class="anchor hidden-xs" href="#volumedetect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-volumedetect" aria-hidden="true">TOC</a></span></h3>
<p>Detect the volume of the input video.
</p>
<p>The filter has no parameters. The input is not modified. Statistics about
the volume will be printed in the log when the input stream end is reached.
</p>
<p>In particular it will show the mean volume (root mean square), maximum
volume (on a per-sample basis), and the beginning of a histogram of the
registered volume values (from the maximum value to a cumulated 1/1000 of
the samples).
</p>
<p>All volumes are in decibels relative to the maximum PCM value.
</p>
<a name="Examples-47"></a>
<h4 class="subsection">34.48.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-47" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-47" aria-hidden="true">TOC</a></span></h4>
<p>Here is an excerpt of the output:
</p><div class="example">
<pre class="example">[Parsed_volumedetect_0 0xa23120] mean_volume: -27 dB
[Parsed_volumedetect_0 0xa23120] max_volume: -4 dB
[Parsed_volumedetect_0 0xa23120] histogram_4db: 6
[Parsed_volumedetect_0 0xa23120] histogram_5db: 62
[Parsed_volumedetect_0 0xa23120] histogram_6db: 286
[Parsed_volumedetect_0 0xa23120] histogram_7db: 1042
[Parsed_volumedetect_0 0xa23120] histogram_8db: 2551
[Parsed_volumedetect_0 0xa23120] histogram_9db: 4609
[Parsed_volumedetect_0 0xa23120] histogram_10db: 8409
</pre></div>
<p>It means that:
</p><ul>
<li> The mean square energy is approximately -27 dB, or 10^-2.7.
</li><li> The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
</li><li> There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
</li></ul>
<p>In other words, raising the volume by +4 dB does not cause any clipping,
raising it by +5 dB causes clipping for 6 samples, etc.
</p>
<a name="Audio-Sources"></a>
<h2 class="chapter">35 Audio Sources<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Sources" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Sources" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available audio sources.
</p>
<a name="abuffer"></a>
<h3 class="section">35.1 abuffer<span class="pull-right"><a class="anchor hidden-xs" href="#abuffer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-abuffer" aria-hidden="true">TOC</a></span></h3>
<p>Buffer audio frames, and make them available to the filter chain.
</p>
<p>This source is mainly intended for a programmatic use, in particular
through the interface defined in <samp>libavfilter/asrc_abuffer.h</samp>.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>time_base</samp></dt>
<dd><p>The timebase which will be used for timestamps of submitted frames. It must be
either a floating-point number or in <var>numerator</var>/<var>denominator</var> form.
</p>
</dd>
<dt><samp>sample_rate</samp></dt>
<dd><p>The sample rate of the incoming audio buffers.
</p>
</dd>
<dt><samp>sample_fmt</samp></dt>
<dd><p>The sample format of the incoming audio buffers.
Either a sample format name or its corresponding integer representation from
the enum AVSampleFormat in <samp>libavutil/samplefmt.h</samp>
</p>
</dd>
<dt><samp>channel_layout</samp></dt>
<dd><p>The channel layout of the incoming audio buffers.
Either a channel layout name from channel_layout_map in
<samp>libavutil/channel_layout.c</samp> or its corresponding integer representation
from the AV_CH_LAYOUT_* macros in <samp>libavutil/channel_layout.h</samp>
</p>
</dd>
<dt><samp>channels</samp></dt>
<dd><p>The number of channels of the incoming audio buffers.
If both <var>channels</var> and <var>channel_layout</var> are specified, then they
must be consistent.
</p>
</dd>
</dl>
<a name="Examples-48"></a>
<h4 class="subsection">35.1.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-48" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-48" aria-hidden="true">TOC</a></span></h4>
<div class="example">
<pre class="example">abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
</pre></div>
<p>will instruct the source to accept planar 16bit signed stereo at 44100Hz.
Since the sample format with name "s16p" corresponds to the number
6 and the "stereo" channel layout corresponds to the value 0x3, this is
equivalent to:
</p><div class="example">
<pre class="example">abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
</pre></div>
<a name="aevalsrc"></a>
<h3 class="section">35.2 aevalsrc<span class="pull-right"><a class="anchor hidden-xs" href="#aevalsrc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aevalsrc" aria-hidden="true">TOC</a></span></h3>
<p>Generate an audio signal specified by an expression.
</p>
<p>This source accepts in input one or more expressions (one for each
channel), which are evaluated and used to generate a corresponding
audio signal.
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>exprs</samp></dt>
<dd><p>Set the ’|’-separated expressions list for each separate channel. In case the
<samp>channel_layout</samp> option is not specified, the selected channel layout
depends on the number of provided expressions. Otherwise the last
specified expression is applied to the remaining output channels.
</p>
</dd>
<dt><samp>channel_layout, c</samp></dt>
<dd><p>Set the channel layout. The number of channels in the specified layout
must be equal to the number of specified expressions.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Set the minimum duration of the sourced audio. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
Note that the resulting duration may be greater than the specified
duration, as the generated audio is always cut at the end of a
complete frame.
</p>
<p>If not specified, or the expressed duration is negative, the audio is
supposed to be generated forever.
</p>
</dd>
<dt><samp>nb_samples, n</samp></dt>
<dd><p>Set the number of samples per channel per each output frame,
default to 1024.
</p>
</dd>
<dt><samp>sample_rate, s</samp></dt>
<dd><p>Specify the sample rate, default to 44100.
</p></dd>
</dl>
<p>Each expression in <var>exprs</var> can contain the following constants:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>number of the evaluated sample, starting from 0
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>time of the evaluated sample expressed in seconds, starting from 0
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>sample rate
</p>
</dd>
</dl>
<a name="Examples-49"></a>
<h4 class="subsection">35.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-49" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-49" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Generate silence:
<div class="example">
<pre class="example">aevalsrc=0
</pre></div>
</li><li> Generate a sin signal with frequency of 440 Hz, set sample rate to
8000 Hz:
<div class="example">
<pre class="example">aevalsrc="sin(440*2*PI*t):s=8000"
</pre></div>
</li><li> Generate a two channels signal, specify the channel layout (Front
Center + Back Center) explicitly:
<div class="example">
<pre class="example">aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
</pre></div>
</li><li> Generate white noise:
<div class="example">
<pre class="example">aevalsrc="-2+random(0)"
</pre></div>
</li><li> Generate an amplitude modulated signal:
<div class="example">
<pre class="example">aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
</pre></div>
</li><li> Generate 2.5 Hz binaural beats on a 360 Hz carrier:
<div class="example">
<pre class="example">aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
</pre></div>
</li></ul>
<a name="anullsrc"></a>
<h3 class="section">35.3 anullsrc<span class="pull-right"><a class="anchor hidden-xs" href="#anullsrc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-anullsrc" aria-hidden="true">TOC</a></span></h3>
<p>The null audio source, return unprocessed audio frames. It is mainly useful
as a template and to be employed in analysis / debugging tools, or as
the source for filters which ignore the input data (for example the sox
synth filter).
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>channel_layout, cl</samp></dt>
<dd>
<p>Specifies the channel layout, and can be either an integer or a string
representing a channel layout. The default value of <var>channel_layout</var>
is "stereo".
</p>
<p>Check the channel_layout_map definition in
<samp>libavutil/channel_layout.c</samp> for the mapping between strings and
channel layout values.
</p>
</dd>
<dt><samp>sample_rate, r</samp></dt>
<dd><p>Specifies the sample rate, and defaults to 44100.
</p>
</dd>
<dt><samp>nb_samples, n</samp></dt>
<dd><p>Set the number of samples per requested frames.
</p>
</dd>
</dl>
<a name="Examples-50"></a>
<h4 class="subsection">35.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-50" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-50" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
<div class="example">
<pre class="example">anullsrc=r=48000:cl=4
</pre></div>
</li><li> Do the same operation with a more obvious syntax:
<div class="example">
<pre class="example">anullsrc=r=48000:cl=mono
</pre></div>
</li></ul>
<p>All the parameters need to be explicitly defined.
</p>
<a name="flite"></a>
<h3 class="section">35.4 flite<span class="pull-right"><a class="anchor hidden-xs" href="#flite" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-flite" aria-hidden="true">TOC</a></span></h3>
<p>Synthesize a voice utterance using the libflite library.
</p>
<p>To enable compilation of this filter you need to configure FFmpeg with
<code>--enable-libflite</code>.
</p>
<p>Note that the flite library is not thread-safe.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>list_voices</samp></dt>
<dd><p>If set to 1, list the names of the available voices and exit
immediately. Default value is 0.
</p>
</dd>
<dt><samp>nb_samples, n</samp></dt>
<dd><p>Set the maximum number of samples per frame. Default value is 512.
</p>
</dd>
<dt><samp>textfile</samp></dt>
<dd><p>Set the filename containing the text to speak.
</p>
</dd>
<dt><samp>text</samp></dt>
<dd><p>Set the text to speak.
</p>
</dd>
<dt><samp>voice, v</samp></dt>
<dd><p>Set the voice to use for the speech synthesis. Default value is
<code>kal</code>. See also the <var>list_voices</var> option.
</p></dd>
</dl>
<a name="Examples-51"></a>
<h4 class="subsection">35.4.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-51" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-51" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Read from file <samp>speech.txt</samp>, and synthesize the text using the
standard flite voice:
<div class="example">
<pre class="example">flite=textfile=speech.txt
</pre></div>
</li><li> Read the specified text selecting the <code>slt</code> voice:
<div class="example">
<pre class="example">flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
</pre></div>
</li><li> Input text to ffmpeg:
<div class="example">
<pre class="example">ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
</pre></div>
</li><li> Make <samp>ffplay</samp> speak the specified text, using <code>flite</code> and
the <code>lavfi</code> device:
<div class="example">
<pre class="example">ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
</pre></div>
</li></ul>
<p>For more information about libflite, check:
<a href="http://www.speech.cs.cmu.edu/flite/">http://www.speech.cs.cmu.edu/flite/</a>
</p>
<a name="sine"></a>
<h3 class="section">35.5 sine<span class="pull-right"><a class="anchor hidden-xs" href="#sine" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sine" aria-hidden="true">TOC</a></span></h3>
<p>Generate an audio signal made of a sine wave with amplitude 1/8.
</p>
<p>The audio signal is bit-exact.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>frequency, f</samp></dt>
<dd><p>Set the carrier frequency. Default is 440 Hz.
</p>
</dd>
<dt><samp>beep_factor, b</samp></dt>
<dd><p>Enable a periodic beep every second with frequency <var>beep_factor</var> times
the carrier frequency. Default is 0, meaning the beep is disabled.
</p>
</dd>
<dt><samp>sample_rate, r</samp></dt>
<dd><p>Specify the sample rate, default is 44100.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Specify the duration of the generated audio stream.
</p>
</dd>
<dt><samp>samples_per_frame</samp></dt>
<dd><p>Set the number of samples per output frame, default is 1024.
</p></dd>
</dl>
<a name="Examples-52"></a>
<h4 class="subsection">35.5.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-52" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-52" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Generate a simple 440 Hz sine wave:
<div class="example">
<pre class="example">sine
</pre></div>
</li><li> Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
<div class="example">
<pre class="example">sine=220:4:d=5
sine=f=220:b=4:d=5
sine=frequency=220:beep_factor=4:duration=5
</pre></div>
</li></ul>
<a name="Audio-Sinks"></a>
<h2 class="chapter">36 Audio Sinks<span class="pull-right"><a class="anchor hidden-xs" href="#Audio-Sinks" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Audio-Sinks" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available audio sinks.
</p>
<a name="abuffersink"></a>
<h3 class="section">36.1 abuffersink<span class="pull-right"><a class="anchor hidden-xs" href="#abuffersink" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-abuffersink" aria-hidden="true">TOC</a></span></h3>
<p>Buffer audio frames, and make them available to the end of filter chain.
</p>
<p>This sink is mainly intended for programmatic use, in particular
through the interface defined in <samp>libavfilter/buffersink.h</samp>
or the options system.
</p>
<p>It accepts a pointer to an AVABufferSinkContext structure, which
defines the incoming buffers’ formats, to be passed as the opaque
parameter to <code>avfilter_init_filter</code> for initialization.
</p><a name="anullsink"></a>
<h3 class="section">36.2 anullsink<span class="pull-right"><a class="anchor hidden-xs" href="#anullsink" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-anullsink" aria-hidden="true">TOC</a></span></h3>
<p>Null audio sink; do absolutely nothing with the input audio. It is
mainly useful as a template and for use in analysis / debugging
tools.
</p>
<a name="Video-Filters"></a>
<h2 class="chapter">37 Video Filters<span class="pull-right"><a class="anchor hidden-xs" href="#Video-Filters" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-Filters" aria-hidden="true">TOC</a></span></h2>
<p>When you configure your FFmpeg build, you can disable any of the
existing filters using <code>--disable-filters</code>.
The configure output will show the video filters included in your
build.
</p>
<p>Below is a description of the currently available video filters.
</p>
<a name="alphaextract"></a>
<h3 class="section">37.1 alphaextract<span class="pull-right"><a class="anchor hidden-xs" href="#alphaextract" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-alphaextract" aria-hidden="true">TOC</a></span></h3>
<p>Extract the alpha component from the input as a grayscale video. This
is especially useful with the <var>alphamerge</var> filter.
</p>
<a name="alphamerge"></a>
<h3 class="section">37.2 alphamerge<span class="pull-right"><a class="anchor hidden-xs" href="#alphamerge" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-alphamerge" aria-hidden="true">TOC</a></span></h3>
<p>Add or replace the alpha component of the primary input with the
grayscale value of a second input. This is intended for use with
<var>alphaextract</var> to allow the transmission or storage of frame
sequences that have alpha in a format that doesn’t support an alpha
channel.
</p>
<p>For example, to reconstruct full frames from a normal YUV-encoded video
and a separate video created with <var>alphaextract</var>, you might use:
</p><div class="example">
<pre class="example">movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
</pre></div>
<p>Since this filter is designed for reconstruction, it operates on frame
sequences without considering timestamps, and terminates when either
input reaches end of stream. This will cause problems if your encoding
pipeline drops frames. If you’re trying to apply an image as an
overlay to a video stream, consider the <var>overlay</var> filter instead.
</p>
<a name="ass"></a>
<h3 class="section">37.3 ass<span class="pull-right"><a class="anchor hidden-xs" href="#ass" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ass" aria-hidden="true">TOC</a></span></h3>
<p>Same as the <a href="#subtitles">subtitles</a> filter, except that it doesn’t require libavcodec
and libavformat to work. On the other hand, it is limited to ASS (Advanced
Substation Alpha) subtitles files.
</p>
<p>This filter accepts the following option in addition to the common options from
the <a href="#subtitles">subtitles</a> filter:
</p>
<dl compact="compact">
<dt><samp>shaping</samp></dt>
<dd><p>Set the shaping engine
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>The default libass shaping engine, which is the best available.
</p></dd>
<dt>‘<samp>simple</samp>’</dt>
<dd><p>Fast, font-agnostic shaper that can do only substitutions
</p></dd>
<dt>‘<samp>complex</samp>’</dt>
<dd><p>Slower shaper using OpenType for substitutions and positioning
</p></dd>
</dl>
<p>The default is <code>auto</code>.
</p></dd>
</dl>
<a name="atadenoise"></a>
<h3 class="section">37.4 atadenoise<span class="pull-right"><a class="anchor hidden-xs" href="#atadenoise" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-atadenoise" aria-hidden="true">TOC</a></span></h3>
<p>Apply an Adaptive Temporal Averaging Denoiser to the video input.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>0a</samp></dt>
<dd><p>Set threshold A for 1st plane. Default is 0.02.
Valid range is 0 to 0.3.
</p>
</dd>
<dt><samp>0b</samp></dt>
<dd><p>Set threshold B for 1st plane. Default is 0.04.
Valid range is 0 to 5.
</p>
</dd>
<dt><samp>1a</samp></dt>
<dd><p>Set threshold A for 2nd plane. Default is 0.02.
Valid range is 0 to 0.3.
</p>
</dd>
<dt><samp>1b</samp></dt>
<dd><p>Set threshold B for 2nd plane. Default is 0.04.
Valid range is 0 to 5.
</p>
</dd>
<dt><samp>2a</samp></dt>
<dd><p>Set threshold A for 3rd plane. Default is 0.02.
Valid range is 0 to 0.3.
</p>
</dd>
<dt><samp>2b</samp></dt>
<dd><p>Set threshold B for 3rd plane. Default is 0.04.
Valid range is 0 to 5.
</p>
<p>Threshold A is designed to react on abrupt changes in the input signal and
threshold B is designed to react on continuous changes in the input signal.
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>Set number of frames filter will use for averaging. Default is 33. Must be odd
number in range [5, 129].
</p></dd>
</dl>
<a name="bbox"></a>
<h3 class="section">37.5 bbox<span class="pull-right"><a class="anchor hidden-xs" href="#bbox" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-bbox" aria-hidden="true">TOC</a></span></h3>
<p>Compute the bounding box for the non-black pixels in the input frame
luminance plane.
</p>
<p>This filter computes the bounding box containing all the pixels with a
luminance value greater than the minimum allowed value.
The parameters describing the bounding box are printed on the filter
log.
</p>
<p>The filter accepts the following option:
</p>
<dl compact="compact">
<dt><samp>min_val</samp></dt>
<dd><p>Set the minimal luminance value. Default is <code>16</code>.
</p></dd>
</dl>
<a name="blackdetect"></a>
<h3 class="section">37.6 blackdetect<span class="pull-right"><a class="anchor hidden-xs" href="#blackdetect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-blackdetect" aria-hidden="true">TOC</a></span></h3>
<p>Detect video intervals that are (almost) completely black. Can be
useful to detect chapter transitions, commercials, or invalid
recordings. Output lines contains the time for the start, end and
duration of the detected black interval expressed in seconds.
</p>
<p>In order to display the output lines, you need to set the loglevel at
least to the AV_LOG_INFO value.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>black_min_duration, d</samp></dt>
<dd><p>Set the minimum detected black duration expressed in seconds. It must
be a non-negative floating point number.
</p>
<p>Default value is 2.0.
</p>
</dd>
<dt><samp>picture_black_ratio_th, pic_th</samp></dt>
<dd><p>Set the threshold for considering a picture "black".
Express the minimum value for the ratio:
</p><div class="example">
<pre class="example"><var>nb_black_pixels</var> / <var>nb_pixels</var>
</pre></div>
<p>for which a picture is considered black.
Default value is 0.98.
</p>
</dd>
<dt><samp>pixel_black_th, pix_th</samp></dt>
<dd><p>Set the threshold for considering a pixel "black".
</p>
<p>The threshold expresses the maximum pixel luminance value for which a
pixel is considered "black". The provided value is scaled according to
the following equation:
</p><div class="example">
<pre class="example"><var>absolute_threshold</var> = <var>luminance_minimum_value</var> + <var>pixel_black_th</var> * <var>luminance_range_size</var>
</pre></div>
<p><var>luminance_range_size</var> and <var>luminance_minimum_value</var> depend on
the input video format, the range is [0-255] for YUV full-range
formats and [16-235] for YUV non full-range formats.
</p>
<p>Default value is 0.10.
</p></dd>
</dl>
<p>The following example sets the maximum pixel threshold to the minimum
value, and detects only black intervals of 2 or more seconds:
</p><div class="example">
<pre class="example">blackdetect=d=2:pix_th=0.00
</pre></div>
<a name="blackframe"></a>
<h3 class="section">37.7 blackframe<span class="pull-right"><a class="anchor hidden-xs" href="#blackframe" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-blackframe" aria-hidden="true">TOC</a></span></h3>
<p>Detect frames that are (almost) completely black. Can be useful to
detect chapter transitions or commercials. Output lines consist of
the frame number of the detected frame, the percentage of blackness,
the position in the file if known or -1 and the timestamp in seconds.
</p>
<p>In order to display the output lines, you need to set the loglevel at
least to the AV_LOG_INFO value.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>amount</samp></dt>
<dd><p>The percentage of the pixels that have to be below the threshold; it defaults to
<code>98</code>.
</p>
</dd>
<dt><samp>threshold, thresh</samp></dt>
<dd><p>The threshold below which a pixel value is considered black; it defaults to
<code>32</code>.
</p>
</dd>
</dl>
<a name="blend_002c-tblend"></a>
<h3 class="section">37.8 blend, tblend<span class="pull-right"><a class="anchor hidden-xs" href="#blend_002c-tblend" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-blend_002c-tblend" aria-hidden="true">TOC</a></span></h3>
<p>Blend two video frames into each other.
</p>
<p>The <code>blend</code> filter takes two input streams and outputs one
stream, the first input is the "top" layer and second input is
"bottom" layer. Output terminates when shortest input terminates.
</p>
<p>The <code>tblend</code> (time blend) filter takes two consecutive frames
from one single stream, and outputs the result obtained by blending
the new frame on top of the old frame.
</p>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>c0_mode</samp></dt>
<dt><samp>c1_mode</samp></dt>
<dt><samp>c2_mode</samp></dt>
<dt><samp>c3_mode</samp></dt>
<dt><samp>all_mode</samp></dt>
<dd><p>Set blend mode for specific pixel component or all pixel components in case
of <var>all_mode</var>. Default value is <code>normal</code>.
</p>
<p>Available values for component modes are:
</p><dl compact="compact">
<dt>‘<samp>addition</samp>’</dt>
<dt>‘<samp>and</samp>’</dt>
<dt>‘<samp>average</samp>’</dt>
<dt>‘<samp>burn</samp>’</dt>
<dt>‘<samp>darken</samp>’</dt>
<dt>‘<samp>difference</samp>’</dt>
<dt>‘<samp>difference128</samp>’</dt>
<dt>‘<samp>divide</samp>’</dt>
<dt>‘<samp>dodge</samp>’</dt>
<dt>‘<samp>exclusion</samp>’</dt>
<dt>‘<samp>glow</samp>’</dt>
<dt>‘<samp>hardlight</samp>’</dt>
<dt>‘<samp>hardmix</samp>’</dt>
<dt>‘<samp>lighten</samp>’</dt>
<dt>‘<samp>linearlight</samp>’</dt>
<dt>‘<samp>multiply</samp>’</dt>
<dt>‘<samp>negation</samp>’</dt>
<dt>‘<samp>normal</samp>’</dt>
<dt>‘<samp>or</samp>’</dt>
<dt>‘<samp>overlay</samp>’</dt>
<dt>‘<samp>phoenix</samp>’</dt>
<dt>‘<samp>pinlight</samp>’</dt>
<dt>‘<samp>reflect</samp>’</dt>
<dt>‘<samp>screen</samp>’</dt>
<dt>‘<samp>softlight</samp>’</dt>
<dt>‘<samp>subtract</samp>’</dt>
<dt>‘<samp>vividlight</samp>’</dt>
<dt>‘<samp>xor</samp>’</dt>
</dl>
</dd>
<dt><samp>c0_opacity</samp></dt>
<dt><samp>c1_opacity</samp></dt>
<dt><samp>c2_opacity</samp></dt>
<dt><samp>c3_opacity</samp></dt>
<dt><samp>all_opacity</samp></dt>
<dd><p>Set blend opacity for specific pixel component or all pixel components in case
of <var>all_opacity</var>. Only used in combination with pixel component blend modes.
</p>
</dd>
<dt><samp>c0_expr</samp></dt>
<dt><samp>c1_expr</samp></dt>
<dt><samp>c2_expr</samp></dt>
<dt><samp>c3_expr</samp></dt>
<dt><samp>all_expr</samp></dt>
<dd><p>Set blend expression for specific pixel component or all pixel components in case
of <var>all_expr</var>. Note that related mode options will be ignored if those are set.
</p>
<p>The expressions can use the following variables:
</p>
<dl compact="compact">
<dt><samp>N</samp></dt>
<dd><p>The sequential number of the filtered frame, starting from <code>0</code>.
</p>
</dd>
<dt><samp>X</samp></dt>
<dt><samp>Y</samp></dt>
<dd><p>the coordinates of the current sample
</p>
</dd>
<dt><samp>W</samp></dt>
<dt><samp>H</samp></dt>
<dd><p>the width and height of currently filtered plane
</p>
</dd>
<dt><samp>SW</samp></dt>
<dt><samp>SH</samp></dt>
<dd><p>Width and height scale depending on the currently filtered plane. It is the
ratio between the corresponding luma plane number of pixels and the current
plane ones. E.g. for YUV4:2:0 the values are <code>1,1</code> for the luma plane, and
<code>0.5,0.5</code> for chroma planes.
</p>
</dd>
<dt><samp>T</samp></dt>
<dd><p>Time of the current frame, expressed in seconds.
</p>
</dd>
<dt><samp>TOP, A</samp></dt>
<dd><p>Value of pixel component at current location for first video frame (top layer).
</p>
</dd>
<dt><samp>BOTTOM, B</samp></dt>
<dd><p>Value of pixel component at current location for second video frame (bottom layer).
</p></dd>
</dl>
</dd>
<dt><samp>shortest</samp></dt>
<dd><p>Force termination when the shortest input terminates. Default is
<code>0</code>. This option is only defined for the <code>blend</code> filter.
</p>
</dd>
<dt><samp>repeatlast</samp></dt>
<dd><p>Continue applying the last bottom frame after the end of the stream. A value of
<code>0</code> disable the filter after the last frame of the bottom layer is reached.
Default is <code>1</code>. This option is only defined for the <code>blend</code> filter.
</p></dd>
</dl>
<a name="Examples-53"></a>
<h4 class="subsection">37.8.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-53" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-53" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply transition from bottom layer to top layer in first 10 seconds:
<div class="example">
<pre class="example">blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
</pre></div>
</li><li> Apply 1x1 checkerboard effect:
<div class="example">
<pre class="example">blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
</pre></div>
</li><li> Apply uncover left effect:
<div class="example">
<pre class="example">blend=all_expr='if(gte(N*SW+X,W),A,B)'
</pre></div>
</li><li> Apply uncover down effect:
<div class="example">
<pre class="example">blend=all_expr='if(gte(Y-N*SH,0),A,B)'
</pre></div>
</li><li> Apply uncover up-left effect:
<div class="example">
<pre class="example">blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
</pre></div>
</li><li> Display differences between the current and the previous frame:
<div class="example">
<pre class="example">tblend=all_mode=difference128
</pre></div>
</li></ul>
<a name="boxblur"></a>
<h3 class="section">37.9 boxblur<span class="pull-right"><a class="anchor hidden-xs" href="#boxblur" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-boxblur" aria-hidden="true">TOC</a></span></h3>
<p>Apply a boxblur algorithm to the input video.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>luma_radius, lr</samp></dt>
<dt><samp>luma_power, lp</samp></dt>
<dt><samp>chroma_radius, cr</samp></dt>
<dt><samp>chroma_power, cp</samp></dt>
<dt><samp>alpha_radius, ar</samp></dt>
<dt><samp>alpha_power, ap</samp></dt>
</dl>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>luma_radius, lr</samp></dt>
<dt><samp>chroma_radius, cr</samp></dt>
<dt><samp>alpha_radius, ar</samp></dt>
<dd><p>Set an expression for the box radius in pixels used for blurring the
corresponding input plane.
</p>
<p>The radius value must be a non-negative number, and must not be
greater than the value of the expression <code>min(w,h)/2</code> for the
luma and alpha planes, and of <code>min(cw,ch)/2</code> for the chroma
planes.
</p>
<p>Default value for <samp>luma_radius</samp> is "2". If not specified,
<samp>chroma_radius</samp> and <samp>alpha_radius</samp> default to the
corresponding value set for <samp>luma_radius</samp>.
</p>
<p>The expressions can contain the following constants:
</p><dl compact="compact">
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>The input width and height in pixels.
</p>
</dd>
<dt><samp>cw</samp></dt>
<dt><samp>ch</samp></dt>
<dd><p>The input chroma image width and height in pixels.
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>The horizontal and vertical chroma subsample values. For example, for the
pixel format "yuv422p", <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p></dd>
</dl>
</dd>
<dt><samp>luma_power, lp</samp></dt>
<dt><samp>chroma_power, cp</samp></dt>
<dt><samp>alpha_power, ap</samp></dt>
<dd><p>Specify how many times the boxblur filter is applied to the
corresponding plane.
</p>
<p>Default value for <samp>luma_power</samp> is 2. If not specified,
<samp>chroma_power</samp> and <samp>alpha_power</samp> default to the
corresponding value set for <samp>luma_power</samp>.
</p>
<p>A value of 0 will disable the effect.
</p></dd>
</dl>
<a name="Examples-54"></a>
<h4 class="subsection">37.9.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-54" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-54" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply a boxblur filter with the luma, chroma, and alpha radii
set to 2:
<div class="example">
<pre class="example">boxblur=luma_radius=2:luma_power=1
boxblur=2:1
</pre></div>
</li><li> Set the luma radius to 2, and alpha and chroma radius to 0:
<div class="example">
<pre class="example">boxblur=2:1:cr=0:ar=0
</pre></div>
</li><li> Set the luma and chroma radii to a fraction of the video dimension:
<div class="example">
<pre class="example">boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
</pre></div>
</li></ul>
<a name="codecview"></a>
<h3 class="section">37.10 codecview<span class="pull-right"><a class="anchor hidden-xs" href="#codecview" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-codecview" aria-hidden="true">TOC</a></span></h3>
<p>Visualize information exported by some codecs.
</p>
<p>Some codecs can export information through frames using side-data or other
means. For example, some MPEG based codecs export motion vectors through the
<var>export_mvs</var> flag in the codec <samp>flags2</samp> option.
</p>
<p>The filter accepts the following option:
</p>
<dl compact="compact">
<dt><samp>mv</samp></dt>
<dd><p>Set motion vectors to visualize.
</p>
<p>Available flags for <var>mv</var> are:
</p>
<dl compact="compact">
<dt>‘<samp>pf</samp>’</dt>
<dd><p>forward predicted MVs of P-frames
</p></dd>
<dt>‘<samp>bf</samp>’</dt>
<dd><p>forward predicted MVs of B-frames
</p></dd>
<dt>‘<samp>bb</samp>’</dt>
<dd><p>backward predicted MVs of B-frames
</p></dd>
</dl>
</dd>
</dl>
<a name="Examples-55"></a>
<h4 class="subsection">37.10.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-55" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-55" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Visualizes multi-directionals MVs from P and B-Frames using <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
</pre></div>
</li></ul>
<a name="colorbalance"></a>
<h3 class="section">37.11 colorbalance<span class="pull-right"><a class="anchor hidden-xs" href="#colorbalance" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-colorbalance" aria-hidden="true">TOC</a></span></h3>
<p>Modify intensity of primary colors (red, green and blue) of input frames.
</p>
<p>The filter allows an input frame to be adjusted in the shadows, midtones or highlights
regions for the red-cyan, green-magenta or blue-yellow balance.
</p>
<p>A positive adjustment value shifts the balance towards the primary color, a negative
value towards the complementary color.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rs</samp></dt>
<dt><samp>gs</samp></dt>
<dt><samp>bs</samp></dt>
<dd><p>Adjust red, green and blue shadows (darkest pixels).
</p>
</dd>
<dt><samp>rm</samp></dt>
<dt><samp>gm</samp></dt>
<dt><samp>bm</samp></dt>
<dd><p>Adjust red, green and blue midtones (medium pixels).
</p>
</dd>
<dt><samp>rh</samp></dt>
<dt><samp>gh</samp></dt>
<dt><samp>bh</samp></dt>
<dd><p>Adjust red, green and blue highlights (brightest pixels).
</p>
<p>Allowed ranges for options are <code>[-1.0, 1.0]</code>. Defaults are <code>0</code>.
</p></dd>
</dl>
<a name="Examples-56"></a>
<h4 class="subsection">37.11.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-56" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-56" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Add red color cast to shadows:
<div class="example">
<pre class="example">colorbalance=rs=.3
</pre></div>
</li></ul>
<a name="colorkey"></a>
<h3 class="section">37.12 colorkey<span class="pull-right"><a class="anchor hidden-xs" href="#colorkey" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-colorkey" aria-hidden="true">TOC</a></span></h3>
<p>RGB colorspace color keying.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>color</samp></dt>
<dd><p>The color which will be replaced with transparency.
</p>
</dd>
<dt><samp>similarity</samp></dt>
<dd><p>Similarity percentage with the key color.
</p>
<p>0.01 matches only the exact key color, while 1.0 matches everything.
</p>
</dd>
<dt><samp>blend</samp></dt>
<dd><p>Blend percentage.
</p>
<p>0.0 makes pixels either fully transparent, or not transparent at all.
</p>
<p>Higher values result in semi-transparent pixels, with a higher transparency
the more similar the pixels color is to the key color.
</p></dd>
</dl>
<a name="Examples-57"></a>
<h4 class="subsection">37.12.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-57" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-57" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Make every green pixel in the input image transparent:
<div class="example">
<pre class="example">ffmpeg -i input.png -vf colorkey=green out.png
</pre></div>
</li><li> Overlay a greenscreen-video on top of a static background image.
<div class="example">
<pre class="example">ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv
</pre></div>
</li></ul>
<a name="colorlevels"></a>
<h3 class="section">37.13 colorlevels<span class="pull-right"><a class="anchor hidden-xs" href="#colorlevels" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-colorlevels" aria-hidden="true">TOC</a></span></h3>
<p>Adjust video input frames using levels.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rimin</samp></dt>
<dt><samp>gimin</samp></dt>
<dt><samp>bimin</samp></dt>
<dt><samp>aimin</samp></dt>
<dd><p>Adjust red, green, blue and alpha input black point.
Allowed ranges for options are <code>[-1.0, 1.0]</code>. Defaults are <code>0</code>.
</p>
</dd>
<dt><samp>rimax</samp></dt>
<dt><samp>gimax</samp></dt>
<dt><samp>bimax</samp></dt>
<dt><samp>aimax</samp></dt>
<dd><p>Adjust red, green, blue and alpha input white point.
Allowed ranges for options are <code>[-1.0, 1.0]</code>. Defaults are <code>1</code>.
</p>
<p>Input levels are used to lighten highlights (bright tones), darken shadows
(dark tones), change the balance of bright and dark tones.
</p>
</dd>
<dt><samp>romin</samp></dt>
<dt><samp>gomin</samp></dt>
<dt><samp>bomin</samp></dt>
<dt><samp>aomin</samp></dt>
<dd><p>Adjust red, green, blue and alpha output black point.
Allowed ranges for options are <code>[0, 1.0]</code>. Defaults are <code>0</code>.
</p>
</dd>
<dt><samp>romax</samp></dt>
<dt><samp>gomax</samp></dt>
<dt><samp>bomax</samp></dt>
<dt><samp>aomax</samp></dt>
<dd><p>Adjust red, green, blue and alpha output white point.
Allowed ranges for options are <code>[0, 1.0]</code>. Defaults are <code>1</code>.
</p>
<p>Output levels allows manual selection of a constrained output level range.
</p></dd>
</dl>
<a name="Examples-58"></a>
<h4 class="subsection">37.13.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-58" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-58" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Make video output darker:
<div class="example">
<pre class="example">colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
</pre></div>
</li><li> Increase contrast:
<div class="example">
<pre class="example">colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
</pre></div>
</li><li> Make video output lighter:
<div class="example">
<pre class="example">colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
</pre></div>
</li><li> Increase brightness:
<div class="example">
<pre class="example">colorlevels=romin=0.5:gomin=0.5:bomin=0.5
</pre></div>
</li></ul>
<a name="colorchannelmixer"></a>
<h3 class="section">37.14 colorchannelmixer<span class="pull-right"><a class="anchor hidden-xs" href="#colorchannelmixer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-colorchannelmixer" aria-hidden="true">TOC</a></span></h3>
<p>Adjust video input frames by re-mixing color channels.
</p>
<p>This filter modifies a color channel by adding the values associated to
the other channels of the same pixels. For example if the value to
modify is red, the output value will be:
</p><div class="example">
<pre class="example"><var>red</var>=<var>red</var>*<var>rr</var> + <var>blue</var>*<var>rb</var> + <var>green</var>*<var>rg</var> + <var>alpha</var>*<var>ra</var>
</pre></div>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rr</samp></dt>
<dt><samp>rg</samp></dt>
<dt><samp>rb</samp></dt>
<dt><samp>ra</samp></dt>
<dd><p>Adjust contribution of input red, green, blue and alpha channels for output red channel.
Default is <code>1</code> for <var>rr</var>, and <code>0</code> for <var>rg</var>, <var>rb</var> and <var>ra</var>.
</p>
</dd>
<dt><samp>gr</samp></dt>
<dt><samp>gg</samp></dt>
<dt><samp>gb</samp></dt>
<dt><samp>ga</samp></dt>
<dd><p>Adjust contribution of input red, green, blue and alpha channels for output green channel.
Default is <code>1</code> for <var>gg</var>, and <code>0</code> for <var>gr</var>, <var>gb</var> and <var>ga</var>.
</p>
</dd>
<dt><samp>br</samp></dt>
<dt><samp>bg</samp></dt>
<dt><samp>bb</samp></dt>
<dt><samp>ba</samp></dt>
<dd><p>Adjust contribution of input red, green, blue and alpha channels for output blue channel.
Default is <code>1</code> for <var>bb</var>, and <code>0</code> for <var>br</var>, <var>bg</var> and <var>ba</var>.
</p>
</dd>
<dt><samp>ar</samp></dt>
<dt><samp>ag</samp></dt>
<dt><samp>ab</samp></dt>
<dt><samp>aa</samp></dt>
<dd><p>Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
Default is <code>1</code> for <var>aa</var>, and <code>0</code> for <var>ar</var>, <var>ag</var> and <var>ab</var>.
</p>
<p>Allowed ranges for options are <code>[-2.0, 2.0]</code>.
</p></dd>
</dl>
<a name="Examples-59"></a>
<h4 class="subsection">37.14.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-59" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-59" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Convert source to grayscale:
<div class="example">
<pre class="example">colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
</pre></div>
</li><li> Simulate sepia tones:
<div class="example">
<pre class="example">colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
</pre></div>
</li></ul>
<a name="colormatrix"></a>
<h3 class="section">37.15 colormatrix<span class="pull-right"><a class="anchor hidden-xs" href="#colormatrix" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-colormatrix" aria-hidden="true">TOC</a></span></h3>
<p>Convert color matrix.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>src</samp></dt>
<dt><samp>dst</samp></dt>
<dd><p>Specify the source and destination color matrix. Both values must be
specified.
</p>
<p>The accepted values are:
</p><dl compact="compact">
<dt>‘<samp>bt709</samp>’</dt>
<dd><p>BT.709
</p>
</dd>
<dt>‘<samp>bt601</samp>’</dt>
<dd><p>BT.601
</p>
</dd>
<dt>‘<samp>smpte240m</samp>’</dt>
<dd><p>SMPTE-240M
</p>
</dd>
<dt>‘<samp>fcc</samp>’</dt>
<dd><p>FCC
</p></dd>
</dl>
</dd>
</dl>
<p>For example to convert from BT.601 to SMPTE-240M, use the command:
</p><div class="example">
<pre class="example">colormatrix=bt601:smpte240m
</pre></div>
<a name="copy"></a>
<h3 class="section">37.16 copy<span class="pull-right"><a class="anchor hidden-xs" href="#copy" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-copy" aria-hidden="true">TOC</a></span></h3>
<p>Copy the input source unchanged to the output. This is mainly useful for
testing purposes.
</p>
<a name="crop"></a>
<h3 class="section">37.17 crop<span class="pull-right"><a class="anchor hidden-xs" href="#crop" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-crop" aria-hidden="true">TOC</a></span></h3>
<p>Crop the input video to given dimensions.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>w, out_w</samp></dt>
<dd><p>The width of the output video. It defaults to <code>iw</code>.
This expression is evaluated only once during the filter
configuration, or when the ‘<samp>w</samp>’ or ‘<samp>out_w</samp>’ command is sent.
</p>
</dd>
<dt><samp>h, out_h</samp></dt>
<dd><p>The height of the output video. It defaults to <code>ih</code>.
This expression is evaluated only once during the filter
configuration, or when the ‘<samp>h</samp>’ or ‘<samp>out_h</samp>’ command is sent.
</p>
</dd>
<dt><samp>x</samp></dt>
<dd><p>The horizontal position, in the input video, of the left edge of the output
video. It defaults to <code>(in_w-out_w)/2</code>.
This expression is evaluated per-frame.
</p>
</dd>
<dt><samp>y</samp></dt>
<dd><p>The vertical position, in the input video, of the top edge of the output video.
It defaults to <code>(in_h-out_h)/2</code>.
This expression is evaluated per-frame.
</p>
</dd>
<dt><samp>keep_aspect</samp></dt>
<dd><p>If set to 1 will force the output display aspect ratio
to be the same of the input, by changing the output sample aspect
ratio. It defaults to 0.
</p></dd>
</dl>
<p>The <var>out_w</var>, <var>out_h</var>, <var>x</var>, <var>y</var> parameters are
expressions containing the following constants:
</p>
<dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The computed values for <var>x</var> and <var>y</var>. They are evaluated for
each new frame.
</p>
</dd>
<dt><samp>in_w</samp></dt>
<dt><samp>in_h</samp></dt>
<dd><p>The input width and height.
</p>
</dd>
<dt><samp>iw</samp></dt>
<dt><samp>ih</samp></dt>
<dd><p>These are the same as <var>in_w</var> and <var>in_h</var>.
</p>
</dd>
<dt><samp>out_w</samp></dt>
<dt><samp>out_h</samp></dt>
<dd><p>The output (cropped) width and height.
</p>
</dd>
<dt><samp>ow</samp></dt>
<dt><samp>oh</samp></dt>
<dd><p>These are the same as <var>out_w</var> and <var>out_h</var>.
</p>
</dd>
<dt><samp>a</samp></dt>
<dd><p>same as <var>iw</var> / <var>ih</var>
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>input sample aspect ratio
</p>
</dd>
<dt><samp>dar</samp></dt>
<dd><p>input display aspect ratio, it is the same as (<var>iw</var> / <var>ih</var>) * <var>sar</var>
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>The number of the input frame, starting from 0.
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>the position in the file of the input frame, NAN if unknown
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>The timestamp expressed in seconds. It’s NAN if the input timestamp is unknown.
</p>
</dd>
</dl>
<p>The expression for <var>out_w</var> may depend on the value of <var>out_h</var>,
and the expression for <var>out_h</var> may depend on <var>out_w</var>, but they
cannot depend on <var>x</var> and <var>y</var>, as <var>x</var> and <var>y</var> are
evaluated after <var>out_w</var> and <var>out_h</var>.
</p>
<p>The <var>x</var> and <var>y</var> parameters specify the expressions for the
position of the top-left corner of the output (non-cropped) area. They
are evaluated for each frame. If the evaluated value is not valid, it
is approximated to the nearest valid value.
</p>
<p>The expression for <var>x</var> may depend on <var>y</var>, and the expression
for <var>y</var> may depend on <var>x</var>.
</p>
<a name="Examples-60"></a>
<h4 class="subsection">37.17.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-60" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-60" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Crop area with size 100x100 at position (12,34).
<div class="example">
<pre class="example">crop=100:100:12:34
</pre></div>
<p>Using named options, the example above becomes:
</p><div class="example">
<pre class="example">crop=w=100:h=100:x=12:y=34
</pre></div>
</li><li> Crop the central input area with size 100x100:
<div class="example">
<pre class="example">crop=100:100
</pre></div>
</li><li> Crop the central input area with size 2/3 of the input video:
<div class="example">
<pre class="example">crop=2/3*in_w:2/3*in_h
</pre></div>
</li><li> Crop the input video central square:
<div class="example">
<pre class="example">crop=out_w=in_h
crop=in_h
</pre></div>
</li><li> Delimit the rectangle with the top-left corner placed at position
100:100 and the right-bottom corner corresponding to the right-bottom
corner of the input image.
<div class="example">
<pre class="example">crop=in_w-100:in_h-100:100:100
</pre></div>
</li><li> Crop 10 pixels from the left and right borders, and 20 pixels from
the top and bottom borders
<div class="example">
<pre class="example">crop=in_w-2*10:in_h-2*20
</pre></div>
</li><li> Keep only the bottom right quarter of the input image:
<div class="example">
<pre class="example">crop=in_w/2:in_h/2:in_w/2:in_h/2
</pre></div>
</li><li> Crop height for getting Greek harmony:
<div class="example">
<pre class="example">crop=in_w:1/PHI*in_w
</pre></div>
</li><li> Apply trembling effect:
<div class="example">
<pre class="example">crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
</pre></div>
</li><li> Apply erratic camera effect depending on timestamp:
<div class="example">
<pre class="example">crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
</pre></div>
</li><li> Set x depending on the value of y:
<div class="example">
<pre class="example">crop=in_w/2:in_h/2:y:10+10*sin(n/10)
</pre></div>
</li></ul>
<a name="Commands-2"></a>
<h4 class="subsection">37.17.2 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-2" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>w, out_w</samp></dt>
<dt><samp>h, out_h</samp></dt>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Set width/height of the output video and the horizontal/vertical position
in the input video.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
</dl>
<a name="cropdetect"></a>
<h3 class="section">37.18 cropdetect<span class="pull-right"><a class="anchor hidden-xs" href="#cropdetect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-cropdetect" aria-hidden="true">TOC</a></span></h3>
<p>Auto-detect the crop size.
</p>
<p>It calculates the necessary cropping parameters and prints the
recommended parameters via the logging system. The detected dimensions
correspond to the non-black area of the input video.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>limit</samp></dt>
<dd><p>Set higher black value threshold, which can be optionally specified
from nothing (0) to everything (255 for 8bit based formats). An intensity
value greater to the set value is considered non-black. It defaults to 24.
You can also specify a value between 0.0 and 1.0 which will be scaled depending
on the bitdepth of the pixel format.
</p>
</dd>
<dt><samp>round</samp></dt>
<dd><p>The value which the width/height should be divisible by. It defaults to
16. The offset is automatically adjusted to center the video. Use 2 to
get only even dimensions (needed for 4:2:2 video). 16 is best when
encoding to most video codecs.
</p>
</dd>
<dt><samp>reset_count, reset</samp></dt>
<dd><p>Set the counter that determines after how many frames cropdetect will
reset the previously detected largest video area and start over to
detect the current optimal crop area. Default value is 0.
</p>
<p>This can be useful when channel logos distort the video area. 0
indicates ’never reset’, and returns the largest area encountered during
playback.
</p></dd>
</dl>
<a name="curves"></a><a name="curves-1"></a>
<h3 class="section">37.19 curves<span class="pull-right"><a class="anchor hidden-xs" href="#curves-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-curves-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply color adjustments using curves.
</p>
<p>This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
component (red, green and blue) has its values defined by <var>N</var> key points
tied from each other using a smooth curve. The x-axis represents the pixel
values from the input frame, and the y-axis the new pixel values to be set for
the output frame.
</p>
<p>By default, a component curve is defined by the two points <var>(0;0)</var> and
<var>(1;1)</var>. This creates a straight line where each original pixel value is
"adjusted" to its own value, which means no change to the image.
</p>
<p>The filter allows you to redefine these two points and add some more. A new
curve (using a natural cubic spline interpolation) will be define to pass
smoothly through all these new coordinates. The new defined points needs to be
strictly increasing over the x-axis, and their <var>x</var> and <var>y</var> values must
be in the <var>[0;1]</var> interval. If the computed curves happened to go outside
the vector spaces, the values will be clipped accordingly.
</p>
<p>If there is no key point defined in <code>x=0</code>, the filter will automatically
insert a <var>(0;0)</var> point. In the same way, if there is no key point defined
in <code>x=1</code>, the filter will automatically insert a <var>(1;1)</var> point.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>preset</samp></dt>
<dd><p>Select one of the available color presets. This option can be used in addition
to the <samp>r</samp>, <samp>g</samp>, <samp>b</samp> parameters; in this case, the later
options takes priority on the preset values.
Available presets are:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dt>‘<samp>color_negative</samp>’</dt>
<dt>‘<samp>cross_process</samp>’</dt>
<dt>‘<samp>darker</samp>’</dt>
<dt>‘<samp>increase_contrast</samp>’</dt>
<dt>‘<samp>lighter</samp>’</dt>
<dt>‘<samp>linear_contrast</samp>’</dt>
<dt>‘<samp>medium_contrast</samp>’</dt>
<dt>‘<samp>negative</samp>’</dt>
<dt>‘<samp>strong_contrast</samp>’</dt>
<dt>‘<samp>vintage</samp>’</dt>
</dl>
<p>Default is <code>none</code>.
</p></dd>
<dt><samp>master, m</samp></dt>
<dd><p>Set the master key points. These points will define a second pass mapping. It
is sometimes called a "luminance" or "value" mapping. It can be used with
<samp>r</samp>, <samp>g</samp>, <samp>b</samp> or <samp>all</samp> since it acts like a
post-processing LUT.
</p></dd>
<dt><samp>red, r</samp></dt>
<dd><p>Set the key points for the red component.
</p></dd>
<dt><samp>green, g</samp></dt>
<dd><p>Set the key points for the green component.
</p></dd>
<dt><samp>blue, b</samp></dt>
<dd><p>Set the key points for the blue component.
</p></dd>
<dt><samp>all</samp></dt>
<dd><p>Set the key points for all components (not including master).
Can be used in addition to the other key points component
options. In this case, the unset component(s) will fallback on this
<samp>all</samp> setting.
</p></dd>
<dt><samp>psfile</samp></dt>
<dd><p>Specify a Photoshop curves file (<code>.asv</code>) to import the settings from.
</p></dd>
</dl>
<p>To avoid some filtergraph syntax conflicts, each key points list need to be
defined using the following syntax: <code>x0/y0 x1/y1 x2/y2 ...</code>.
</p>
<a name="Examples-61"></a>
<h4 class="subsection">37.19.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-61" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-61" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Increase slightly the middle level of blue:
<div class="example">
<pre class="example">curves=blue='0.5/0.58'
</pre></div>
</li><li> Vintage effect:
<div class="example">
<pre class="example">curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
</pre></div>
<p>Here we obtain the following coordinates for each components:
</p><dl compact="compact">
<dt><var>red</var></dt>
<dd><p><code>(0;0.11) (0.42;0.51) (1;0.95)</code>
</p></dd>
<dt><var>green</var></dt>
<dd><p><code>(0;0) (0.50;0.48) (1;1)</code>
</p></dd>
<dt><var>blue</var></dt>
<dd><p><code>(0;0.22) (0.49;0.44) (1;0.80)</code>
</p></dd>
</dl>
</li><li> The previous example can also be achieved with the associated built-in preset:
<div class="example">
<pre class="example">curves=preset=vintage
</pre></div>
</li><li> Or simply:
<div class="example">
<pre class="example">curves=vintage
</pre></div>
</li><li> Use a Photoshop preset and redefine the points of the green component:
<div class="example">
<pre class="example">curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
</pre></div>
</li></ul>
<a name="dctdnoiz"></a>
<h3 class="section">37.20 dctdnoiz<span class="pull-right"><a class="anchor hidden-xs" href="#dctdnoiz" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dctdnoiz" aria-hidden="true">TOC</a></span></h3>
<p>Denoise frames using 2D DCT (frequency domain filtering).
</p>
<p>This filter is not designed for real time.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>sigma, s</samp></dt>
<dd><p>Set the noise sigma constant.
</p>
<p>This <var>sigma</var> defines a hard threshold of <code>3 * sigma</code>; every DCT
coefficient (absolute value) below this threshold with be dropped.
</p>
<p>If you need a more advanced filtering, see <samp>expr</samp>.
</p>
<p>Default is <code>0</code>.
</p>
</dd>
<dt><samp>overlap</samp></dt>
<dd><p>Set number overlapping pixels for each block. Since the filter can be slow, you
may want to reduce this value, at the cost of a less effective filter and the
risk of various artefacts.
</p>
<p>If the overlapping value doesn’t permit processing the whole input width or
height, a warning will be displayed and according borders won’t be denoised.
</p>
<p>Default value is <var>blocksize</var>-1, which is the best possible setting.
</p>
</dd>
<dt><samp>expr, e</samp></dt>
<dd><p>Set the coefficient factor expression.
</p>
<p>For each coefficient of a DCT block, this expression will be evaluated as a
multiplier value for the coefficient.
</p>
<p>If this is option is set, the <samp>sigma</samp> option will be ignored.
</p>
<p>The absolute value of the coefficient can be accessed through the <var>c</var>
variable.
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>Set the <var>blocksize</var> using the number of bits. <code>1<<<var>n</var></code> defines the
<var>blocksize</var>, which is the width and height of the processed blocks.
</p>
<p>The default value is <var>3</var> (8x8) and can be raised to <var>4</var> for a
<var>blocksize</var> of 16x16. Note that changing this setting has huge consequences
on the speed processing. Also, a larger block size does not necessarily means a
better de-noising.
</p></dd>
</dl>
<a name="Examples-62"></a>
<h4 class="subsection">37.20.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-62" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-62" aria-hidden="true">TOC</a></span></h4>
<p>Apply a denoise with a <samp>sigma</samp> of <code>4.5</code>:
</p><div class="example">
<pre class="example">dctdnoiz=4.5
</pre></div>
<p>The same operation can be achieved using the expression system:
</p><div class="example">
<pre class="example">dctdnoiz=e='gte(c, 4.5*3)'
</pre></div>
<p>Violent denoise using a block size of <code>16x16</code>:
</p><div class="example">
<pre class="example">dctdnoiz=15:n=4
</pre></div>
<a name="deband"></a>
<h3 class="section">37.21 deband<span class="pull-right"><a class="anchor hidden-xs" href="#deband" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-deband" aria-hidden="true">TOC</a></span></h3>
<p>Remove banding artifacts from input video.
It works by replacing banded pixels with average value of referenced pixels.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>1thr</samp></dt>
<dt><samp>2thr</samp></dt>
<dt><samp>3thr</samp></dt>
<dt><samp>4thr</samp></dt>
<dd><p>Set banding detection threshold for each plane. Default is 0.02.
Valid range is 0.00003 to 0.5.
If difference between current pixel and reference pixel is less than threshold,
it will be considered as banded.
</p>
</dd>
<dt><samp>range, r</samp></dt>
<dd><p>Banding detection range in pixels. Default is 16. If positive, random number
in range 0 to set value will be used. If negative, exact absolute value
will be used.
The range defines square of four pixels around current pixel.
</p>
</dd>
<dt><samp>direction, d</samp></dt>
<dd><p>Set direction in radians from which four pixel will be compared. If positive,
random direction from 0 to set direction will be picked. If negative, exact of
absolute value will be picked. For example direction 0, -PI or -2*PI radians
will pick only pixels on same row and -PI/2 will pick only pixels on same
column.
</p>
</dd>
<dt><samp>blur</samp></dt>
<dd><p>If enabled, current pixel is compared with average value of all four
surrounding pixels. The default is enabled. If disabled current pixel is
compared with all four surrounding pixels. The pixel is considered banded
if only all four differences with surrounding pixels are less than threshold.
</p></dd>
</dl>
<a name="decimate"></a><a name="decimate-1"></a>
<h3 class="section">37.22 decimate<span class="pull-right"><a class="anchor hidden-xs" href="#decimate-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-decimate-1" aria-hidden="true">TOC</a></span></h3>
<p>Drop duplicated frames at regular intervals.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>cycle</samp></dt>
<dd><p>Set the number of frames from which one will be dropped. Setting this to
<var>N</var> means one frame in every batch of <var>N</var> frames will be dropped.
Default is <code>5</code>.
</p>
</dd>
<dt><samp>dupthresh</samp></dt>
<dd><p>Set the threshold for duplicate detection. If the difference metric for a frame
is less than or equal to this value, then it is declared as duplicate. Default
is <code>1.1</code>
</p>
</dd>
<dt><samp>scthresh</samp></dt>
<dd><p>Set scene change threshold. Default is <code>15</code>.
</p>
</dd>
<dt><samp>blockx</samp></dt>
<dt><samp>blocky</samp></dt>
<dd><p>Set the size of the x and y-axis blocks used during metric calculations.
Larger blocks give better noise suppression, but also give worse detection of
small movements. Must be a power of two. Default is <code>32</code>.
</p>
</dd>
<dt><samp>ppsrc</samp></dt>
<dd><p>Mark main input as a pre-processed input and activate clean source input
stream. This allows the input to be pre-processed with various filters to help
the metrics calculation while keeping the frame selection lossless. When set to
<code>1</code>, the first stream is for the pre-processed input, and the second
stream is the clean source from where the kept frames are chosen. Default is
<code>0</code>.
</p>
</dd>
<dt><samp>chroma</samp></dt>
<dd><p>Set whether or not chroma is considered in the metric calculations. Default is
<code>1</code>.
</p></dd>
</dl>
<a name="deflate"></a>
<h3 class="section">37.23 deflate<span class="pull-right"><a class="anchor hidden-xs" href="#deflate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-deflate" aria-hidden="true">TOC</a></span></h3>
<p>Apply deflate effect to the video.
</p>
<p>This filter replaces the pixel by the local(3x3) average by taking into account
only values lower than the pixel.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>threshold0</samp></dt>
<dt><samp>threshold1</samp></dt>
<dt><samp>threshold2</samp></dt>
<dt><samp>threshold3</samp></dt>
<dd><p>Limit the maximum change for each plane, default is 65535.
If 0, plane will remain unchanged.
</p></dd>
</dl>
<a name="dejudder"></a>
<h3 class="section">37.24 dejudder<span class="pull-right"><a class="anchor hidden-xs" href="#dejudder" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dejudder" aria-hidden="true">TOC</a></span></h3>
<p>Remove judder produced by partially interlaced telecined content.
</p>
<p>Judder can be introduced, for instance, by <a href="#pullup">pullup</a> filter. If the original
source was partially telecined content then the output of <code>pullup,dejudder</code>
will have a variable frame rate. May change the recorded frame rate of the
container. Aside from that change, this filter will not affect constant frame
rate video.
</p>
<p>The option available in this filter is:
</p><dl compact="compact">
<dt><samp>cycle</samp></dt>
<dd><p>Specify the length of the window over which the judder repeats.
</p>
<p>Accepts any integer greater than 1. Useful values are:
</p><dl compact="compact">
<dt>‘<samp>4</samp>’</dt>
<dd><p>If the original was telecined from 24 to 30 fps (Film to NTSC).
</p>
</dd>
<dt>‘<samp>5</samp>’</dt>
<dd><p>If the original was telecined from 25 to 30 fps (PAL to NTSC).
</p>
</dd>
<dt>‘<samp>20</samp>’</dt>
<dd><p>If a mixture of the two.
</p></dd>
</dl>
<p>The default is ‘<samp>4</samp>’.
</p></dd>
</dl>
<a name="delogo"></a>
<h3 class="section">37.25 delogo<span class="pull-right"><a class="anchor hidden-xs" href="#delogo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-delogo" aria-hidden="true">TOC</a></span></h3>
<p>Suppress a TV station logo by a simple interpolation of the surrounding
pixels. Just set a rectangle covering the logo and watch it disappear
(and sometimes something even uglier appear - your mileage may vary).
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Specify the top left corner coordinates of the logo. They must be
specified.
</p>
</dd>
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>Specify the width and height of the logo to clear. They must be
specified.
</p>
</dd>
<dt><samp>band, t</samp></dt>
<dd><p>Specify the thickness of the fuzzy edge of the rectangle (added to
<var>w</var> and <var>h</var>). The default value is 4.
</p>
</dd>
<dt><samp>show</samp></dt>
<dd><p>When set to 1, a green rectangle is drawn on the screen to simplify
finding the right <var>x</var>, <var>y</var>, <var>w</var>, and <var>h</var> parameters.
The default value is 0.
</p>
<p>The rectangle is drawn on the outermost pixels which will be (partly)
replaced with interpolated values. The values of the next pixels
immediately outside this rectangle in each direction will be used to
compute the interpolated pixel values inside the rectangle.
</p>
</dd>
</dl>
<a name="Examples-63"></a>
<h4 class="subsection">37.25.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-63" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-63" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Set a rectangle covering the area with top left corner coordinates 0,0
and size 100x77, and a band of size 10:
<div class="example">
<pre class="example">delogo=x=0:y=0:w=100:h=77:band=10
</pre></div>
</li></ul>
<a name="deshake"></a>
<h3 class="section">37.26 deshake<span class="pull-right"><a class="anchor hidden-xs" href="#deshake" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-deshake" aria-hidden="true">TOC</a></span></h3>
<p>Attempt to fix small changes in horizontal and/or vertical shift. This
filter helps remove camera shake from hand-holding a camera, bumping a
tripod, moving on a vehicle, etc.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>Specify a rectangular area where to limit the search for motion
vectors.
If desired the search for motion vectors can be limited to a
rectangular area of the frame defined by its top left corner, width
and height. These parameters have the same meaning as the drawbox
filter which can be used to visualise the position of the bounding
box.
</p>
<p>This is useful when simultaneous movement of subjects within the frame
might be confused for camera motion by the motion vector search.
</p>
<p>If any or all of <var>x</var>, <var>y</var>, <var>w</var> and <var>h</var> are set to -1
then the full frame is used. This allows later options to be set
without specifying the bounding box for the motion vector search.
</p>
<p>Default - search the whole frame.
</p>
</dd>
<dt><samp>rx</samp></dt>
<dt><samp>ry</samp></dt>
<dd><p>Specify the maximum extent of movement in x and y directions in the
range 0-64 pixels. Default 16.
</p>
</dd>
<dt><samp>edge</samp></dt>
<dd><p>Specify how to generate pixels to fill blanks at the edge of the
frame. Available values are:
</p><dl compact="compact">
<dt>‘<samp>blank, 0</samp>’</dt>
<dd><p>Fill zeroes at blank locations
</p></dd>
<dt>‘<samp>original, 1</samp>’</dt>
<dd><p>Original image at blank locations
</p></dd>
<dt>‘<samp>clamp, 2</samp>’</dt>
<dd><p>Extruded edge value at blank locations
</p></dd>
<dt>‘<samp>mirror, 3</samp>’</dt>
<dd><p>Mirrored edge at blank locations
</p></dd>
</dl>
<p>Default value is ‘<samp>mirror</samp>’.
</p>
</dd>
<dt><samp>blocksize</samp></dt>
<dd><p>Specify the blocksize to use for motion search. Range 4-128 pixels,
default 8.
</p>
</dd>
<dt><samp>contrast</samp></dt>
<dd><p>Specify the contrast threshold for blocks. Only blocks with more than
the specified contrast (difference between darkest and lightest
pixels) will be considered. Range 1-255, default 125.
</p>
</dd>
<dt><samp>search</samp></dt>
<dd><p>Specify the search strategy. Available values are:
</p><dl compact="compact">
<dt>‘<samp>exhaustive, 0</samp>’</dt>
<dd><p>Set exhaustive search
</p></dd>
<dt>‘<samp>less, 1</samp>’</dt>
<dd><p>Set less exhaustive search.
</p></dd>
</dl>
<p>Default value is ‘<samp>exhaustive</samp>’.
</p>
</dd>
<dt><samp>filename</samp></dt>
<dd><p>If set then a detailed log of the motion search is written to the
specified file.
</p>
</dd>
<dt><samp>opencl</samp></dt>
<dd><p>If set to 1, specify using OpenCL capabilities, only available if
FFmpeg was configured with <code>--enable-opencl</code>. Default value is 0.
</p>
</dd>
</dl>
<a name="detelecine"></a>
<h3 class="section">37.27 detelecine<span class="pull-right"><a class="anchor hidden-xs" href="#detelecine" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-detelecine" aria-hidden="true">TOC</a></span></h3>
<p>Apply an exact inverse of the telecine operation. It requires a predefined
pattern specified using the pattern option which must be the same as that passed
to the telecine filter.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>first_field</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>top, t</samp>’</dt>
<dd><p>top field first
</p></dd>
<dt>‘<samp>bottom, b</samp>’</dt>
<dd><p>bottom field first
The default value is <code>top</code>.
</p></dd>
</dl>
</dd>
<dt><samp>pattern</samp></dt>
<dd><p>A string of numbers representing the pulldown pattern you wish to apply.
The default value is <code>23</code>.
</p>
</dd>
<dt><samp>start_frame</samp></dt>
<dd><p>A number representing position of the first frame with respect to the telecine
pattern. This is to be used if the stream is cut. The default value is <code>0</code>.
</p></dd>
</dl>
<a name="dilation"></a>
<h3 class="section">37.28 dilation<span class="pull-right"><a class="anchor hidden-xs" href="#dilation" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dilation" aria-hidden="true">TOC</a></span></h3>
<p>Apply dilation effect to the video.
</p>
<p>This filter replaces the pixel by the local(3x3) maximum.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>threshold0</samp></dt>
<dt><samp>threshold1</samp></dt>
<dt><samp>threshold2</samp></dt>
<dt><samp>threshold3</samp></dt>
<dd><p>Limit the maximum change for each plane, default is 65535.
If 0, plane will remain unchanged.
</p>
</dd>
<dt><samp>coordinates</samp></dt>
<dd><p>Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
pixels are used.
</p>
<p>Flags to local 3x3 coordinates maps like this:
</p>
<p>1 2 3
4 5
6 7 8
</p></dd>
</dl>
<a name="drawbox"></a>
<h3 class="section">37.29 drawbox<span class="pull-right"><a class="anchor hidden-xs" href="#drawbox" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-drawbox" aria-hidden="true">TOC</a></span></h3>
<p>Draw a colored box on the input image.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The expressions which specify the top left corner coordinates of the box. It defaults to 0.
</p>
</dd>
<dt><samp>width, w</samp></dt>
<dt><samp>height, h</samp></dt>
<dd><p>The expressions which specify the width and height of the box; if 0 they are interpreted as
the input width and height. It defaults to 0.
</p>
</dd>
<dt><samp>color, c</samp></dt>
<dd><p>Specify the color of the box to write. For the general syntax of this option,
check the "Color" section in the ffmpeg-utils manual. If the special
value <code>invert</code> is used, the box edge color is the same as the
video with inverted luma.
</p>
</dd>
<dt><samp>thickness, t</samp></dt>
<dd><p>The expression which sets the thickness of the box edge. Default value is <code>3</code>.
</p>
<p>See below for the list of accepted constants.
</p></dd>
</dl>
<p>The parameters for <var>x</var>, <var>y</var>, <var>w</var> and <var>h</var> and <var>t</var> are expressions containing the
following constants:
</p>
<dl compact="compact">
<dt><samp>dar</samp></dt>
<dd><p>The input display aspect ratio, it is the same as (<var>w</var> / <var>h</var>) * <var>sar</var>.
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><samp>in_h, ih</samp></dt>
<dt><samp>in_w, iw</samp></dt>
<dd><p>The input width and height.
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>The input sample aspect ratio.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The x and y offset coordinates where the box is drawn.
</p>
</dd>
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>The width and height of the drawn box.
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>The thickness of the drawn box.
</p>
<p>These constants allow the <var>x</var>, <var>y</var>, <var>w</var>, <var>h</var> and <var>t</var> expressions to refer to
each other, so you may for example specify <code>y=x/dar</code> or <code>h=w/dar</code>.
</p>
</dd>
</dl>
<a name="Examples-64"></a>
<h4 class="subsection">37.29.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-64" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-64" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Draw a black box around the edge of the input image:
<div class="example">
<pre class="example">drawbox
</pre></div>
</li><li> Draw a box with color red and an opacity of 50%:
<div class="example">
<pre class="example">drawbox=10:20:200:60:red@0.5
</pre></div>
<p>The previous example can be specified as:
</p><div class="example">
<pre class="example">drawbox=x=10:y=20:w=200:h=60:color=red@0.5
</pre></div>
</li><li> Fill the box with pink color:
<div class="example">
<pre class="example">drawbox=x=10:y=10:w=100:h=100:color=pink@0.5:t=max
</pre></div>
</li><li> Draw a 2-pixel red 2.40:1 mask:
<div class="example">
<pre class="example">drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
</pre></div>
</li></ul>
<a name="drawgraph_002c-adrawgraph"></a>
<h3 class="section">37.30 drawgraph, adrawgraph<span class="pull-right"><a class="anchor hidden-xs" href="#drawgraph_002c-adrawgraph" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-drawgraph_002c-adrawgraph" aria-hidden="true">TOC</a></span></h3>
<p>Draw a graph using input video or audio metadata.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>m1</samp></dt>
<dd><p>Set 1st frame metadata key from which metadata values will be used to draw a graph.
</p>
</dd>
<dt><samp>fg1</samp></dt>
<dd><p>Set 1st foreground color expression.
</p>
</dd>
<dt><samp>m2</samp></dt>
<dd><p>Set 2nd frame metadata key from which metadata values will be used to draw a graph.
</p>
</dd>
<dt><samp>fg2</samp></dt>
<dd><p>Set 2nd foreground color expression.
</p>
</dd>
<dt><samp>m3</samp></dt>
<dd><p>Set 3rd frame metadata key from which metadata values will be used to draw a graph.
</p>
</dd>
<dt><samp>fg3</samp></dt>
<dd><p>Set 3rd foreground color expression.
</p>
</dd>
<dt><samp>m4</samp></dt>
<dd><p>Set 4th frame metadata key from which metadata values will be used to draw a graph.
</p>
</dd>
<dt><samp>fg4</samp></dt>
<dd><p>Set 4th foreground color expression.
</p>
</dd>
<dt><samp>min</samp></dt>
<dd><p>Set minimal value of metadata value.
</p>
</dd>
<dt><samp>max</samp></dt>
<dd><p>Set maximal value of metadata value.
</p>
</dd>
<dt><samp>bg</samp></dt>
<dd><p>Set graph background color. Default is white.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set graph mode.
</p>
<p>Available values for mode is:
</p><dl compact="compact">
<dt>‘<samp>bar</samp>’</dt>
<dt>‘<samp>dot</samp>’</dt>
<dt>‘<samp>line</samp>’</dt>
</dl>
<p>Default is <code>line</code>.
</p>
</dd>
<dt><samp>slide</samp></dt>
<dd><p>Set slide mode.
</p>
<p>Available values for slide is:
</p><dl compact="compact">
<dt>‘<samp>frame</samp>’</dt>
<dd><p>Draw new frame when right border is reached.
</p>
</dd>
<dt>‘<samp>replace</samp>’</dt>
<dd><p>Replace old columns with new ones.
</p>
</dd>
<dt>‘<samp>scroll</samp>’</dt>
<dd><p>Scroll from right to left.
</p>
</dd>
<dt>‘<samp>rscroll</samp>’</dt>
<dd><p>Scroll from left to right.
</p></dd>
</dl>
<p>Default is <code>frame</code>.
</p>
</dd>
<dt><samp>size</samp></dt>
<dd><p>Set size of graph video. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
The default value is <code>900x256</code>.
</p>
<p>The foreground color expressions can use the following variables:
</p><dl compact="compact">
<dt><samp>MIN</samp></dt>
<dd><p>Minimal value of metadata value.
</p>
</dd>
<dt><samp>MAX</samp></dt>
<dd><p>Maximal value of metadata value.
</p>
</dd>
<dt><samp>VAL</samp></dt>
<dd><p>Current metadata key value.
</p></dd>
</dl>
<p>The color is defined as 0xAABBGGRR.
</p></dd>
</dl>
<p>Example using metadata from <a href="#signalstats">signalstats</a> filter:
</p><div class="example">
<pre class="example">signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
</pre></div>
<p>Example using metadata from <a href="#ebur128">ebur128</a> filter:
</p><div class="example">
<pre class="example">ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
</pre></div>
<a name="drawgrid"></a>
<h3 class="section">37.31 drawgrid<span class="pull-right"><a class="anchor hidden-xs" href="#drawgrid" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-drawgrid" aria-hidden="true">TOC</a></span></h3>
<p>Draw a grid on the input image.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
</p>
</dd>
<dt><samp>width, w</samp></dt>
<dt><samp>height, h</samp></dt>
<dd><p>The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
input width and height, respectively, minus <code>thickness</code>, so image gets
framed. Default to 0.
</p>
</dd>
<dt><samp>color, c</samp></dt>
<dd><p>Specify the color of the grid. For the general syntax of this option,
check the "Color" section in the ffmpeg-utils manual. If the special
value <code>invert</code> is used, the grid color is the same as the
video with inverted luma.
</p>
</dd>
<dt><samp>thickness, t</samp></dt>
<dd><p>The expression which sets the thickness of the grid line. Default value is <code>1</code>.
</p>
<p>See below for the list of accepted constants.
</p></dd>
</dl>
<p>The parameters for <var>x</var>, <var>y</var>, <var>w</var> and <var>h</var> and <var>t</var> are expressions containing the
following constants:
</p>
<dl compact="compact">
<dt><samp>dar</samp></dt>
<dd><p>The input display aspect ratio, it is the same as (<var>w</var> / <var>h</var>) * <var>sar</var>.
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><samp>in_h, ih</samp></dt>
<dt><samp>in_w, iw</samp></dt>
<dd><p>The input grid cell width and height.
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>The input sample aspect ratio.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The x and y coordinates of some point of grid intersection (meant to configure offset).
</p>
</dd>
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>The width and height of the drawn cell.
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>The thickness of the drawn cell.
</p>
<p>These constants allow the <var>x</var>, <var>y</var>, <var>w</var>, <var>h</var> and <var>t</var> expressions to refer to
each other, so you may for example specify <code>y=x/dar</code> or <code>h=w/dar</code>.
</p>
</dd>
</dl>
<a name="Examples-65"></a>
<h4 class="subsection">37.31.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-65" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-65" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
<div class="example">
<pre class="example">drawgrid=width=100:height=100:thickness=2:color=red@0.5
</pre></div>
</li><li> Draw a white 3x3 grid with an opacity of 50%:
<div class="example">
<pre class="example">drawgrid=w=iw/3:h=ih/3:t=2:c=white@0.5
</pre></div>
</li></ul>
<a name="drawtext"></a><a name="drawtext-1"></a>
<h3 class="section">37.32 drawtext<span class="pull-right"><a class="anchor hidden-xs" href="#drawtext-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-drawtext-1" aria-hidden="true">TOC</a></span></h3>
<p>Draw a text string or text from a specified file on top of a video, using the
libfreetype library.
</p>
<p>To enable compilation of this filter, you need to configure FFmpeg with
<code>--enable-libfreetype</code>.
To enable default font fallback and the <var>font</var> option you need to
configure FFmpeg with <code>--enable-libfontconfig</code>.
To enable the <var>text_shaping</var> option, you need to configure FFmpeg with
<code>--enable-libfribidi</code>.
</p>
<a name="Syntax-2"></a>
<h4 class="subsection">37.32.1 Syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Syntax-2" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Syntax-2" aria-hidden="true">TOC</a></span></h4>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>box</samp></dt>
<dd><p>Used to draw a box around text using the background color.
The value must be either 1 (enable) or 0 (disable).
The default value of <var>box</var> is 0.
</p>
</dd>
<dt><samp>boxborderw</samp></dt>
<dd><p>Set the width of the border to be drawn around the box using <var>boxcolor</var>.
The default value of <var>boxborderw</var> is 0.
</p>
</dd>
<dt><samp>boxcolor</samp></dt>
<dd><p>The color to be used for drawing box around text. For the syntax of this
option, check the "Color" section in the ffmpeg-utils manual.
</p>
<p>The default value of <var>boxcolor</var> is "white".
</p>
</dd>
<dt><samp>borderw</samp></dt>
<dd><p>Set the width of the border to be drawn around the text using <var>bordercolor</var>.
The default value of <var>borderw</var> is 0.
</p>
</dd>
<dt><samp>bordercolor</samp></dt>
<dd><p>Set the color to be used for drawing border around text. For the syntax of this
option, check the "Color" section in the ffmpeg-utils manual.
</p>
<p>The default value of <var>bordercolor</var> is "black".
</p>
</dd>
<dt><samp>expansion</samp></dt>
<dd><p>Select how the <var>text</var> is expanded. Can be either <code>none</code>,
<code>strftime</code> (deprecated) or
<code>normal</code> (default). See the <a href="#drawtext_005fexpansion">Text expansion</a> section
below for details.
</p>
</dd>
<dt><samp>fix_bounds</samp></dt>
<dd><p>If true, check and fix text coords to avoid clipping.
</p>
</dd>
<dt><samp>fontcolor</samp></dt>
<dd><p>The color to be used for drawing fonts. For the syntax of this option, check
the "Color" section in the ffmpeg-utils manual.
</p>
<p>The default value of <var>fontcolor</var> is "black".
</p>
</dd>
<dt><samp>fontcolor_expr</samp></dt>
<dd><p>String which is expanded the same way as <var>text</var> to obtain dynamic
<var>fontcolor</var> value. By default this option has empty value and is not
processed. When this option is set, it overrides <var>fontcolor</var> option.
</p>
</dd>
<dt><samp>font</samp></dt>
<dd><p>The font family to be used for drawing text. By default Sans.
</p>
</dd>
<dt><samp>fontfile</samp></dt>
<dd><p>The font file to be used for drawing text. The path must be included.
This parameter is mandatory if the fontconfig support is disabled.
</p>
</dd>
<dt><samp>draw</samp></dt>
<dd><p>This option does not exist, please see the timeline system
</p>
</dd>
<dt><samp>alpha</samp></dt>
<dd><p>Draw the text applying alpha blending. The value can
be either a number between 0.0 and 1.0
The expression accepts the same variables <var>x, y</var> do.
The default value is 1.
Please see fontcolor_expr
</p>
</dd>
<dt><samp>fontsize</samp></dt>
<dd><p>The font size to be used for drawing text.
The default value of <var>fontsize</var> is 16.
</p>
</dd>
<dt><samp>text_shaping</samp></dt>
<dd><p>If set to 1, attempt to shape the text (for example, reverse the order of
right-to-left text and join Arabic characters) before drawing it.
Otherwise, just draw the text exactly as given.
By default 1 (if supported).
</p>
</dd>
<dt><samp>ft_load_flags</samp></dt>
<dd><p>The flags to be used for loading the fonts.
</p>
<p>The flags map the corresponding flags supported by libfreetype, and are
a combination of the following values:
</p><dl compact="compact">
<dt><var>default</var></dt>
<dt><var>no_scale</var></dt>
<dt><var>no_hinting</var></dt>
<dt><var>render</var></dt>
<dt><var>no_bitmap</var></dt>
<dt><var>vertical_layout</var></dt>
<dt><var>force_autohint</var></dt>
<dt><var>crop_bitmap</var></dt>
<dt><var>pedantic</var></dt>
<dt><var>ignore_global_advance_width</var></dt>
<dt><var>no_recurse</var></dt>
<dt><var>ignore_transform</var></dt>
<dt><var>monochrome</var></dt>
<dt><var>linear_design</var></dt>
<dt><var>no_autohint</var></dt>
</dl>
<p>Default value is "default".
</p>
<p>For more information consult the documentation for the FT_LOAD_*
libfreetype flags.
</p>
</dd>
<dt><samp>shadowcolor</samp></dt>
<dd><p>The color to be used for drawing a shadow behind the drawn text. For the
syntax of this option, check the "Color" section in the ffmpeg-utils manual.
</p>
<p>The default value of <var>shadowcolor</var> is "black".
</p>
</dd>
<dt><samp>shadowx</samp></dt>
<dt><samp>shadowy</samp></dt>
<dd><p>The x and y offsets for the text shadow position with respect to the
position of the text. They can be either positive or negative
values. The default value for both is "0".
</p>
</dd>
<dt><samp>start_number</samp></dt>
<dd><p>The starting frame number for the n/frame_num variable. The default value
is "0".
</p>
</dd>
<dt><samp>tabsize</samp></dt>
<dd><p>The size in number of spaces to use for rendering the tab.
Default value is 4.
</p>
</dd>
<dt><samp>timecode</samp></dt>
<dd><p>Set the initial timecode representation in "hh:mm:ss[:;.]ff"
format. It can be used with or without text parameter. <var>timecode_rate</var>
option must be specified.
</p>
</dd>
<dt><samp>timecode_rate, rate, r</samp></dt>
<dd><p>Set the timecode frame rate (timecode only).
</p>
</dd>
<dt><samp>text</samp></dt>
<dd><p>The text string to be drawn. The text must be a sequence of UTF-8
encoded characters.
This parameter is mandatory if no file is specified with the parameter
<var>textfile</var>.
</p>
</dd>
<dt><samp>textfile</samp></dt>
<dd><p>A text file containing text to be drawn. The text must be a sequence
of UTF-8 encoded characters.
</p>
<p>This parameter is mandatory if no text string is specified with the
parameter <var>text</var>.
</p>
<p>If both <var>text</var> and <var>textfile</var> are specified, an error is thrown.
</p>
</dd>
<dt><samp>reload</samp></dt>
<dd><p>If set to 1, the <var>textfile</var> will be reloaded before each frame.
Be sure to update it atomically, or it may be read partially, or even fail.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The expressions which specify the offsets where text will be drawn
within the video frame. They are relative to the top/left border of the
output image.
</p>
<p>The default value of <var>x</var> and <var>y</var> is "0".
</p>
<p>See below for the list of accepted constants and functions.
</p></dd>
</dl>
<p>The parameters for <var>x</var> and <var>y</var> are expressions containing the
following constants and functions:
</p>
<dl compact="compact">
<dt><samp>dar</samp></dt>
<dd><p>input display aspect ratio, it is the same as (<var>w</var> / <var>h</var>) * <var>sar</var>
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><samp>line_h, lh</samp></dt>
<dd><p>the height of each text line
</p>
</dd>
<dt><samp>main_h, h, H</samp></dt>
<dd><p>the input height
</p>
</dd>
<dt><samp>main_w, w, W</samp></dt>
<dd><p>the input width
</p>
</dd>
<dt><samp>max_glyph_a, ascent</samp></dt>
<dd><p>the maximum distance from the baseline to the highest/upper grid
coordinate used to place a glyph outline point, for all the rendered
glyphs.
It is a positive value, due to the grid’s orientation with the Y axis
upwards.
</p>
</dd>
<dt><samp>max_glyph_d, descent</samp></dt>
<dd><p>the maximum distance from the baseline to the lowest grid coordinate
used to place a glyph outline point, for all the rendered glyphs.
This is a negative value, due to the grid’s orientation, with the Y axis
upwards.
</p>
</dd>
<dt><samp>max_glyph_h</samp></dt>
<dd><p>maximum glyph height, that is the maximum height for all the glyphs
contained in the rendered text, it is equivalent to <var>ascent</var> -
<var>descent</var>.
</p>
</dd>
<dt><samp>max_glyph_w</samp></dt>
<dd><p>maximum glyph width, that is the maximum width for all the glyphs
contained in the rendered text
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>the number of input frame, starting from 0
</p>
</dd>
<dt><samp>rand(min, max)</samp></dt>
<dd><p>return a random number included between <var>min</var> and <var>max</var>
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>The input sample aspect ratio.
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>timestamp expressed in seconds, NAN if the input timestamp is unknown
</p>
</dd>
<dt><samp>text_h, th</samp></dt>
<dd><p>the height of the rendered text
</p>
</dd>
<dt><samp>text_w, tw</samp></dt>
<dd><p>the width of the rendered text
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>the x and y offset coordinates where the text is drawn.
</p>
<p>These parameters allow the <var>x</var> and <var>y</var> expressions to refer
each other, so you can for example specify <code>y=x/dar</code>.
</p></dd>
</dl>
<a name="drawtext_005fexpansion"></a><a name="Text-expansion"></a>
<h4 class="subsection">37.32.2 Text expansion<span class="pull-right"><a class="anchor hidden-xs" href="#Text-expansion" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Text-expansion" aria-hidden="true">TOC</a></span></h4>
<p>If <samp>expansion</samp> is set to <code>strftime</code>,
the filter recognizes strftime() sequences in the provided text and
expands them accordingly. Check the documentation of strftime(). This
feature is deprecated.
</p>
<p>If <samp>expansion</samp> is set to <code>none</code>, the text is printed verbatim.
</p>
<p>If <samp>expansion</samp> is set to <code>normal</code> (which is the default),
the following expansion mechanism is used.
</p>
<p>The backslash character ‘<samp>\</samp>’, followed by any character, always expands to
the second character.
</p>
<p>Sequence of the form <code>%{...}</code> are expanded. The text between the
braces is a function name, possibly followed by arguments separated by ’:’.
If the arguments contain special characters or delimiters (’:’ or ’}’),
they should be escaped.
</p>
<p>Note that they probably must also be escaped as the value for the
<samp>text</samp> option in the filter argument string and as the filter
argument in the filtergraph description, and possibly also for the shell,
that makes up to four levels of escaping; using a text file avoids these
problems.
</p>
<p>The following functions are available:
</p>
<dl compact="compact">
<dt><code>expr, e</code></dt>
<dd><p>The expression evaluation result.
</p>
<p>It must take one argument specifying the expression to be evaluated,
which accepts the same constants and functions as the <var>x</var> and
<var>y</var> values. Note that not all constants should be used, for
example the text size is not known when evaluating the expression, so
the constants <var>text_w</var> and <var>text_h</var> will have an undefined
value.
</p>
</dd>
<dt><code>expr_int_format, eif</code></dt>
<dd><p>Evaluate the expression’s value and output as formatted integer.
</p>
<p>The first argument is the expression to be evaluated, just as for the <var>expr</var> function.
The second argument specifies the output format. Allowed values are ‘<samp>x</samp>’,
‘<samp>X</samp>’, ‘<samp>d</samp>’ and ‘<samp>u</samp>’. They are treated exactly as in the
<code>printf</code> function.
The third parameter is optional and sets the number of positions taken by the output.
It can be used to add padding with zeros from the left.
</p>
</dd>
<dt><code>gmtime</code></dt>
<dd><p>The time at which the filter is running, expressed in UTC.
It can accept an argument: a strftime() format string.
</p>
</dd>
<dt><code>localtime</code></dt>
<dd><p>The time at which the filter is running, expressed in the local time zone.
It can accept an argument: a strftime() format string.
</p>
</dd>
<dt><code>metadata</code></dt>
<dd><p>Frame metadata. It must take one argument specifying metadata key.
</p>
</dd>
<dt><code>n, frame_num</code></dt>
<dd><p>The frame number, starting from 0.
</p>
</dd>
<dt><code>pict_type</code></dt>
<dd><p>A 1 character description of the current picture type.
</p>
</dd>
<dt><code>pts</code></dt>
<dd><p>The timestamp of the current frame.
It can take up to two arguments.
</p>
<p>The first argument is the format of the timestamp; it defaults to <code>flt</code>
for seconds as a decimal number with microsecond accuracy; <code>hms</code> stands
for a formatted <var>[-]HH:MM:SS.mmm</var> timestamp with millisecond accuracy.
</p>
<p>The second argument is an offset added to the timestamp.
</p>
</dd>
</dl>
<a name="Examples-66"></a>
<h4 class="subsection">37.32.3 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-66" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-66" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Draw "Test Text" with font FreeSerif, using the default values for the
optional parameters.
<div class="example">
<pre class="example">drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
</pre></div>
</li><li> Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
and y=50 (counting from the top-left corner of the screen), text is
yellow with a red box around it. Both the text and the box have an
opacity of 20%.
<div class="example">
<pre class="example">drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"
</pre></div>
<p>Note that the double quotes are not necessary if spaces are not used
within the parameter list.
</p>
</li><li> Show the text at the center of the video frame:
<div class="example">
<pre class="example">drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"
</pre></div>
</li><li> Show a text line sliding from right to left in the last row of the video
frame. The file <samp>LONG_LINE</samp> is assumed to contain a single line
with no newlines.
<div class="example">
<pre class="example">drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
</pre></div>
</li><li> Show the content of file <samp>CREDITS</samp> off the bottom of the frame and scroll up.
<div class="example">
<pre class="example">drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
</pre></div>
</li><li> Draw a single green letter "g", at the center of the input video.
The glyph baseline is placed at half screen height.
<div class="example">
<pre class="example">drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
</pre></div>
</li><li> Show text for 1 second every 3 seconds:
<div class="example">
<pre class="example">drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
</pre></div>
</li><li> Use fontconfig to set the font. Note that the colons need to be escaped.
<div class="example">
<pre class="example">drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
</pre></div>
</li><li> Print the date of a real-time encoding (see strftime(3)):
<div class="example">
<pre class="example">drawtext='fontfile=FreeSans.ttf:text=%{localtime\:%a %b %d %Y}'
</pre></div>
</li><li> Show text fading in and out (appearing/disappearing):
<div class="example">
<pre class="example">#!/bin/sh
DS=1.0 # display start
DE=10.0 # display end
FID=1.5 # fade in duration
FOD=5 # fade out duration
ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 }"
</pre></div>
</li></ul>
<p>For more information about libfreetype, check:
<a href="http://www.freetype.org/">http://www.freetype.org/</a>.
</p>
<p>For more information about fontconfig, check:
<a href="http://freedesktop.org/software/fontconfig/fontconfig-user.html">http://freedesktop.org/software/fontconfig/fontconfig-user.html</a>.
</p>
<p>For more information about libfribidi, check:
<a href="http://fribidi.org/">http://fribidi.org/</a>.
</p>
<a name="edgedetect"></a>
<h3 class="section">37.33 edgedetect<span class="pull-right"><a class="anchor hidden-xs" href="#edgedetect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-edgedetect" aria-hidden="true">TOC</a></span></h3>
<p>Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>low</samp></dt>
<dt><samp>high</samp></dt>
<dd><p>Set low and high threshold values used by the Canny thresholding
algorithm.
</p>
<p>The high threshold selects the "strong" edge pixels, which are then
connected through 8-connectivity with the "weak" edge pixels selected
by the low threshold.
</p>
<p><var>low</var> and <var>high</var> threshold values must be chosen in the range
[0,1], and <var>low</var> should be lesser or equal to <var>high</var>.
</p>
<p>Default value for <var>low</var> is <code>20/255</code>, and default value for <var>high</var>
is <code>50/255</code>.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Define the drawing mode.
</p>
<dl compact="compact">
<dt>‘<samp>wires</samp>’</dt>
<dd><p>Draw white/gray wires on black background.
</p>
</dd>
<dt>‘<samp>colormix</samp>’</dt>
<dd><p>Mix the colors to create a paint/cartoon effect.
</p></dd>
</dl>
<p>Default value is <var>wires</var>.
</p></dd>
</dl>
<a name="Examples-67"></a>
<h4 class="subsection">37.33.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-67" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-67" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Standard edge detection with custom values for the hysteresis thresholding:
<div class="example">
<pre class="example">edgedetect=low=0.1:high=0.4
</pre></div>
</li><li> Painting effect without thresholding:
<div class="example">
<pre class="example">edgedetect=mode=colormix:high=0
</pre></div>
</li></ul>
<a name="eq"></a>
<h3 class="section">37.34 eq<span class="pull-right"><a class="anchor hidden-xs" href="#eq" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-eq" aria-hidden="true">TOC</a></span></h3>
<p>Set brightness, contrast, saturation and approximate gamma adjustment.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>contrast</samp></dt>
<dd><p>Set the contrast expression. The value must be a float value in range
<code>-2.0</code> to <code>2.0</code>. The default value is "0".
</p>
</dd>
<dt><samp>brightness</samp></dt>
<dd><p>Set the brightness expression. The value must be a float value in
range <code>-1.0</code> to <code>1.0</code>. The default value is "0".
</p>
</dd>
<dt><samp>saturation</samp></dt>
<dd><p>Set the saturation expression. The value must be a float in
range <code>0.0</code> to <code>3.0</code>. The default value is "1".
</p>
</dd>
<dt><samp>gamma</samp></dt>
<dd><p>Set the gamma expression. The value must be a float in range
<code>0.1</code> to <code>10.0</code>. The default value is "1".
</p>
</dd>
<dt><samp>gamma_r</samp></dt>
<dd><p>Set the gamma expression for red. The value must be a float in
range <code>0.1</code> to <code>10.0</code>. The default value is "1".
</p>
</dd>
<dt><samp>gamma_g</samp></dt>
<dd><p>Set the gamma expression for green. The value must be a float in range
<code>0.1</code> to <code>10.0</code>. The default value is "1".
</p>
</dd>
<dt><samp>gamma_b</samp></dt>
<dd><p>Set the gamma expression for blue. The value must be a float in range
<code>0.1</code> to <code>10.0</code>. The default value is "1".
</p>
</dd>
<dt><samp>gamma_weight</samp></dt>
<dd><p>Set the gamma weight expression. It can be used to reduce the effect
of a high gamma value on bright image areas, e.g. keep them from
getting overamplified and just plain white. The value must be a float
in range <code>0.0</code> to <code>1.0</code>. A value of <code>0.0</code> turns the
gamma correction all the way down while <code>1.0</code> leaves it at its
full strength. Default is "1".
</p>
</dd>
<dt><samp>eval</samp></dt>
<dd><p>Set when the expressions for brightness, contrast, saturation and
gamma expressions are evaluated.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>init</samp>’</dt>
<dd><p>only evaluate expressions once during the filter initialization or
when a command is processed
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>evaluate expressions for each incoming frame
</p></dd>
</dl>
<p>Default value is ‘<samp>init</samp>’.
</p></dd>
</dl>
<p>The expressions accept the following parameters:
</p><dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>frame count of the input frame starting from 0
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>byte position of the corresponding packet in the input file, NAN if
unspecified
</p>
</dd>
<dt><samp>r</samp></dt>
<dd><p>frame rate of the input video, NAN if the input frame rate is unknown
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>timestamp expressed in seconds, NAN if the input timestamp is unknown
</p></dd>
</dl>
<a name="Commands-3"></a>
<h4 class="subsection">37.34.1 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-3" aria-hidden="true">TOC</a></span></h4>
<p>The filter supports the following commands:
</p>
<dl compact="compact">
<dt><samp>contrast</samp></dt>
<dd><p>Set the contrast expression.
</p>
</dd>
<dt><samp>brightness</samp></dt>
<dd><p>Set the brightness expression.
</p>
</dd>
<dt><samp>saturation</samp></dt>
<dd><p>Set the saturation expression.
</p>
</dd>
<dt><samp>gamma</samp></dt>
<dd><p>Set the gamma expression.
</p>
</dd>
<dt><samp>gamma_r</samp></dt>
<dd><p>Set the gamma_r expression.
</p>
</dd>
<dt><samp>gamma_g</samp></dt>
<dd><p>Set gamma_g expression.
</p>
</dd>
<dt><samp>gamma_b</samp></dt>
<dd><p>Set gamma_b expression.
</p>
</dd>
<dt><samp>gamma_weight</samp></dt>
<dd><p>Set gamma_weight expression.
</p>
<p>The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p>
</dd>
</dl>
<a name="erosion"></a>
<h3 class="section">37.35 erosion<span class="pull-right"><a class="anchor hidden-xs" href="#erosion" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-erosion" aria-hidden="true">TOC</a></span></h3>
<p>Apply erosion effect to the video.
</p>
<p>This filter replaces the pixel by the local(3x3) minimum.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>threshold0</samp></dt>
<dt><samp>threshold1</samp></dt>
<dt><samp>threshold2</samp></dt>
<dt><samp>threshold3</samp></dt>
<dd><p>Limit the maximum change for each plane, default is 65535.
If 0, plane will remain unchanged.
</p>
</dd>
<dt><samp>coordinates</samp></dt>
<dd><p>Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
pixels are used.
</p>
<p>Flags to local 3x3 coordinates maps like this:
</p>
<p>1 2 3
4 5
6 7 8
</p></dd>
</dl>
<a name="extractplanes"></a>
<h3 class="section">37.36 extractplanes<span class="pull-right"><a class="anchor hidden-xs" href="#extractplanes" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-extractplanes" aria-hidden="true">TOC</a></span></h3>
<p>Extract color channel components from input video stream into
separate grayscale video streams.
</p>
<p>The filter accepts the following option:
</p>
<dl compact="compact">
<dt><samp>planes</samp></dt>
<dd><p>Set plane(s) to extract.
</p>
<p>Available values for planes are:
</p><dl compact="compact">
<dt>‘<samp>y</samp>’</dt>
<dt>‘<samp>u</samp>’</dt>
<dt>‘<samp>v</samp>’</dt>
<dt>‘<samp>a</samp>’</dt>
<dt>‘<samp>r</samp>’</dt>
<dt>‘<samp>g</samp>’</dt>
<dt>‘<samp>b</samp>’</dt>
</dl>
<p>Choosing planes not available in the input will result in an error.
That means you cannot select <code>r</code>, <code>g</code>, <code>b</code> planes
with <code>y</code>, <code>u</code>, <code>v</code> planes at same time.
</p></dd>
</dl>
<a name="Examples-68"></a>
<h4 class="subsection">37.36.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-68" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-68" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Extract luma, u and v color channel component from input video frame
into 3 grayscale outputs:
<div class="example">
<pre class="example">ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
</pre></div>
</li></ul>
<a name="elbg"></a>
<h3 class="section">37.37 elbg<span class="pull-right"><a class="anchor hidden-xs" href="#elbg" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-elbg" aria-hidden="true">TOC</a></span></h3>
<p>Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
</p>
<p>For each input image, the filter will compute the optimal mapping from
the input to the output given the codebook length, that is the number
of distinct output colors.
</p>
<p>This filter accepts the following options.
</p>
<dl compact="compact">
<dt><samp>codebook_length, l</samp></dt>
<dd><p>Set codebook length. The value must be a positive integer, and
represents the number of distinct output colors. Default value is 256.
</p>
</dd>
<dt><samp>nb_steps, n</samp></dt>
<dd><p>Set the maximum number of iterations to apply for computing the optimal
mapping. The higher the value the better the result and the higher the
computation time. Default value is 1.
</p>
</dd>
<dt><samp>seed, s</samp></dt>
<dd><p>Set a random seed, must be an integer included between 0 and
UINT32_MAX. If not specified, or if explicitly set to -1, the filter
will try to use a good random seed on a best effort basis.
</p>
</dd>
<dt><samp>pal8</samp></dt>
<dd><p>Set pal8 output pixel format. This option does not work with codebook
length greater than 256.
</p></dd>
</dl>
<a name="fade"></a>
<h3 class="section">37.38 fade<span class="pull-right"><a class="anchor hidden-xs" href="#fade" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fade" aria-hidden="true">TOC</a></span></h3>
<p>Apply a fade-in/out effect to the input video.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>type, t</samp></dt>
<dd><p>The effect type can be either "in" for a fade-in, or "out" for a fade-out
effect.
Default is <code>in</code>.
</p>
</dd>
<dt><samp>start_frame, s</samp></dt>
<dd><p>Specify the number of the frame to start applying the fade
effect at. Default is 0.
</p>
</dd>
<dt><samp>nb_frames, n</samp></dt>
<dd><p>The number of frames that the fade effect lasts. At the end of the
fade-in effect, the output video will have the same intensity as the input video.
At the end of the fade-out transition, the output video will be filled with the
selected <samp>color</samp>.
Default is 25.
</p>
</dd>
<dt><samp>alpha</samp></dt>
<dd><p>If set to 1, fade only alpha channel, if one exists on the input.
Default value is 0.
</p>
</dd>
<dt><samp>start_time, st</samp></dt>
<dd><p>Specify the timestamp (in seconds) of the frame to start to apply the fade
effect. If both start_frame and start_time are specified, the fade will start at
whichever comes last. Default is 0.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>The number of seconds for which the fade effect has to last. At the end of the
fade-in effect the output video will have the same intensity as the input video,
at the end of the fade-out transition the output video will be filled with the
selected <samp>color</samp>.
If both duration and nb_frames are specified, duration is used. Default is 0
(nb_frames is used by default).
</p>
</dd>
<dt><samp>color, c</samp></dt>
<dd><p>Specify the color of the fade. Default is "black".
</p></dd>
</dl>
<a name="Examples-69"></a>
<h4 class="subsection">37.38.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-69" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-69" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Fade in the first 30 frames of video:
<div class="example">
<pre class="example">fade=in:0:30
</pre></div>
<p>The command above is equivalent to:
</p><div class="example">
<pre class="example">fade=t=in:s=0:n=30
</pre></div>
</li><li> Fade out the last 45 frames of a 200-frame video:
<div class="example">
<pre class="example">fade=out:155:45
fade=type=out:start_frame=155:nb_frames=45
</pre></div>
</li><li> Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
<div class="example">
<pre class="example">fade=in:0:25, fade=out:975:25
</pre></div>
</li><li> Make the first 5 frames yellow, then fade in from frame 5-24:
<div class="example">
<pre class="example">fade=in:5:20:color=yellow
</pre></div>
</li><li> Fade in alpha over first 25 frames of video:
<div class="example">
<pre class="example">fade=in:0:25:alpha=1
</pre></div>
</li><li> Make the first 5.5 seconds black, then fade in for 0.5 seconds:
<div class="example">
<pre class="example">fade=t=in:st=5.5:d=0.5
</pre></div>
</li></ul>
<a name="fftfilt"></a>
<h3 class="section">37.39 fftfilt<span class="pull-right"><a class="anchor hidden-xs" href="#fftfilt" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fftfilt" aria-hidden="true">TOC</a></span></h3>
<p>Apply arbitrary expressions to samples in frequency domain
</p>
<dl compact="compact">
<dt><samp>dc_Y</samp></dt>
<dd><p>Adjust the dc value (gain) of the luma plane of the image. The filter
accepts an integer value in range <code>0</code> to <code>1000</code>. The default
value is set to <code>0</code>.
</p>
</dd>
<dt><samp>dc_U</samp></dt>
<dd><p>Adjust the dc value (gain) of the 1st chroma plane of the image. The
filter accepts an integer value in range <code>0</code> to <code>1000</code>. The
default value is set to <code>0</code>.
</p>
</dd>
<dt><samp>dc_V</samp></dt>
<dd><p>Adjust the dc value (gain) of the 2nd chroma plane of the image. The
filter accepts an integer value in range <code>0</code> to <code>1000</code>. The
default value is set to <code>0</code>.
</p>
</dd>
<dt><samp>weight_Y</samp></dt>
<dd><p>Set the frequency domain weight expression for the luma plane.
</p>
</dd>
<dt><samp>weight_U</samp></dt>
<dd><p>Set the frequency domain weight expression for the 1st chroma plane.
</p>
</dd>
<dt><samp>weight_V</samp></dt>
<dd><p>Set the frequency domain weight expression for the 2nd chroma plane.
</p>
<p>The filter accepts the following variables:
</p></dd>
<dt><samp>X</samp></dt>
<dt><samp>Y</samp></dt>
<dd><p>The coordinates of the current sample.
</p>
</dd>
<dt><samp>W</samp></dt>
<dt><samp>H</samp></dt>
<dd><p>The width and height of the image.
</p></dd>
</dl>
<a name="Examples-70"></a>
<h4 class="subsection">37.39.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-70" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-70" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> High-pass:
<div class="example">
<pre class="example">fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
</pre></div>
</li><li> Low-pass:
<div class="example">
<pre class="example">fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
</pre></div>
</li><li> Sharpen:
<div class="example">
<pre class="example">fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
</pre></div>
</li></ul>
<a name="field"></a>
<h3 class="section">37.40 field<span class="pull-right"><a class="anchor hidden-xs" href="#field" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-field" aria-hidden="true">TOC</a></span></h3>
<p>Extract a single field from an interlaced image using stride
arithmetic to avoid wasting CPU time. The output frames are marked as
non-interlaced.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>type</samp></dt>
<dd><p>Specify whether to extract the top (if the value is <code>0</code> or
<code>top</code>) or the bottom field (if the value is <code>1</code> or
<code>bottom</code>).
</p></dd>
</dl>
<a name="fieldmatch"></a>
<h3 class="section">37.41 fieldmatch<span class="pull-right"><a class="anchor hidden-xs" href="#fieldmatch" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fieldmatch" aria-hidden="true">TOC</a></span></h3>
<p>Field matching filter for inverse telecine. It is meant to reconstruct the
progressive frames from a telecined stream. The filter does not drop duplicated
frames, so to achieve a complete inverse telecine <code>fieldmatch</code> needs to be
followed by a decimation filter such as <a href="#decimate">decimate</a> in the filtergraph.
</p>
<p>The separation of the field matching and the decimation is notably motivated by
the possibility of inserting a de-interlacing filter fallback between the two.
If the source has mixed telecined and real interlaced content,
<code>fieldmatch</code> will not be able to match fields for the interlaced parts.
But these remaining combed frames will be marked as interlaced, and thus can be
de-interlaced by a later filter such as <a href="#yadif">yadif</a> before decimation.
</p>
<p>In addition to the various configuration options, <code>fieldmatch</code> can take an
optional second stream, activated through the <samp>ppsrc</samp> option. If
enabled, the frames reconstruction will be based on the fields and frames from
this second stream. This allows the first input to be pre-processed in order to
help the various algorithms of the filter, while keeping the output lossless
(assuming the fields are matched properly). Typically, a field-aware denoiser,
or brightness/contrast adjustments can help.
</p>
<p>Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
which <code>fieldmatch</code> is based on. While the semantic and usage are very
close, some behaviour and options names can differ.
</p>
<p>The <a href="#decimate">decimate</a> filter currently only works for constant frame rate input.
If your input has mixed telecined (30fps) and progressive content with a lower
framerate like 24fps use the following filterchain to produce the necessary cfr
stream: <code>dejudder,fps=30000/1001,fieldmatch,decimate</code>.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>order</samp></dt>
<dd><p>Specify the assumed field order of the input stream. Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Auto detect parity (use FFmpeg’s internal parity value).
</p></dd>
<dt>‘<samp>bff</samp>’</dt>
<dd><p>Assume bottom field first.
</p></dd>
<dt>‘<samp>tff</samp>’</dt>
<dd><p>Assume top field first.
</p></dd>
</dl>
<p>Note that it is sometimes recommended not to trust the parity announced by the
stream.
</p>
<p>Default value is <var>auto</var>.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set the matching mode or strategy to use. <samp>pc</samp> mode is the safest in the
sense that it won’t risk creating jerkiness due to duplicate frames when
possible, but if there are bad edits or blended fields it will end up
outputting combed frames when a good match might actually exist. On the other
hand, <samp>pcn_ub</samp> mode is the most risky in terms of creating jerkiness,
but will almost always find a good frame if there is one. The other values are
all somewhere in between <samp>pc</samp> and <samp>pcn_ub</samp> in terms of risking
jerkiness and creating duplicate frames versus finding good matches in sections
with bad edits, orphaned fields, blended fields, etc.
</p>
<p>More details about p/c/n/u/b are available in <a href="#p_002fc_002fn_002fu_002fb-meaning">p/c/n/u/b meaning</a> section.
</p>
<p>Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>pc</samp>’</dt>
<dd><p>2-way matching (p/c)
</p></dd>
<dt>‘<samp>pc_n</samp>’</dt>
<dd><p>2-way matching, and trying 3rd match if still combed (p/c + n)
</p></dd>
<dt>‘<samp>pc_u</samp>’</dt>
<dd><p>2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
</p></dd>
<dt>‘<samp>pc_n_ub</samp>’</dt>
<dd><p>2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
still combed (p/c + n + u/b)
</p></dd>
<dt>‘<samp>pcn</samp>’</dt>
<dd><p>3-way matching (p/c/n)
</p></dd>
<dt>‘<samp>pcn_ub</samp>’</dt>
<dd><p>3-way matching, and trying 4th/5th matches if all 3 of the original matches are
detected as combed (p/c/n + u/b)
</p></dd>
</dl>
<p>The parenthesis at the end indicate the matches that would be used for that
mode assuming <samp>order</samp>=<var>tff</var> (and <samp>field</samp> on <var>auto</var> or
<var>top</var>).
</p>
<p>In terms of speed <samp>pc</samp> mode is by far the fastest and <samp>pcn_ub</samp> is
the slowest.
</p>
<p>Default value is <var>pc_n</var>.
</p>
</dd>
<dt><samp>ppsrc</samp></dt>
<dd><p>Mark the main input stream as a pre-processed input, and enable the secondary
input stream as the clean source to pick the fields from. See the filter
introduction for more details. It is similar to the <samp>clip2</samp> feature from
VFM/TFM.
</p>
<p>Default value is <code>0</code> (disabled).
</p>
</dd>
<dt><samp>field</samp></dt>
<dd><p>Set the field to match from. It is recommended to set this to the same value as
<samp>order</samp> unless you experience matching failures with that setting. In
certain circumstances changing the field that is used to match from can have a
large impact on matching performance. Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Automatic (same value as <samp>order</samp>).
</p></dd>
<dt>‘<samp>bottom</samp>’</dt>
<dd><p>Match from the bottom field.
</p></dd>
<dt>‘<samp>top</samp>’</dt>
<dd><p>Match from the top field.
</p></dd>
</dl>
<p>Default value is <var>auto</var>.
</p>
</dd>
<dt><samp>mchroma</samp></dt>
<dd><p>Set whether or not chroma is included during the match comparisons. In most
cases it is recommended to leave this enabled. You should set this to <code>0</code>
only if your clip has bad chroma problems such as heavy rainbowing or other
artifacts. Setting this to <code>0</code> could also be used to speed things up at
the cost of some accuracy.
</p>
<p>Default value is <code>1</code>.
</p>
</dd>
<dt><samp>y0</samp></dt>
<dt><samp>y1</samp></dt>
<dd><p>These define an exclusion band which excludes the lines between <samp>y0</samp> and
<samp>y1</samp> from being included in the field matching decision. An exclusion
band can be used to ignore subtitles, a logo, or other things that may
interfere with the matching. <samp>y0</samp> sets the starting scan line and
<samp>y1</samp> sets the ending line; all lines in between <samp>y0</samp> and
<samp>y1</samp> (including <samp>y0</samp> and <samp>y1</samp>) will be ignored. Setting
<samp>y0</samp> and <samp>y1</samp> to the same value will disable the feature.
<samp>y0</samp> and <samp>y1</samp> defaults to <code>0</code>.
</p>
</dd>
<dt><samp>scthresh</samp></dt>
<dd><p>Set the scene change detection threshold as a percentage of maximum change on
the luma plane. Good values are in the <code>[8.0, 14.0]</code> range. Scene change
detection is only relevant in case <samp>combmatch</samp>=<var>sc</var>. The range for
<samp>scthresh</samp> is <code>[0.0, 100.0]</code>.
</p>
<p>Default value is <code>12.0</code>.
</p>
</dd>
<dt><samp>combmatch</samp></dt>
<dd><p>When <samp>combatch</samp> is not <var>none</var>, <code>fieldmatch</code> will take into
account the combed scores of matches when deciding what match to use as the
final match. Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>No final matching based on combed scores.
</p></dd>
<dt>‘<samp>sc</samp>’</dt>
<dd><p>Combed scores are only used when a scene change is detected.
</p></dd>
<dt>‘<samp>full</samp>’</dt>
<dd><p>Use combed scores all the time.
</p></dd>
</dl>
<p>Default is <var>sc</var>.
</p>
</dd>
<dt><samp>combdbg</samp></dt>
<dd><p>Force <code>fieldmatch</code> to calculate the combed metrics for certain matches and
print them. This setting is known as <samp>micout</samp> in TFM/VFM vocabulary.
Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>No forced calculation.
</p></dd>
<dt>‘<samp>pcn</samp>’</dt>
<dd><p>Force p/c/n calculations.
</p></dd>
<dt>‘<samp>pcnub</samp>’</dt>
<dd><p>Force p/c/n/u/b calculations.
</p></dd>
</dl>
<p>Default value is <var>none</var>.
</p>
</dd>
<dt><samp>cthresh</samp></dt>
<dd><p>This is the area combing threshold used for combed frame detection. This
essentially controls how "strong" or "visible" combing must be to be detected.
Larger values mean combing must be more visible and smaller values mean combing
can be less visible or strong and still be detected. Valid settings are from
<code>-1</code> (every pixel will be detected as combed) to <code>255</code> (no pixel will
be detected as combed). This is basically a pixel difference value. A good
range is <code>[8, 12]</code>.
</p>
<p>Default value is <code>9</code>.
</p>
</dd>
<dt><samp>chroma</samp></dt>
<dd><p>Sets whether or not chroma is considered in the combed frame decision. Only
disable this if your source has chroma problems (rainbowing, etc.) that are
causing problems for the combed frame detection with chroma enabled. Actually,
using <samp>chroma</samp>=<var>0</var> is usually more reliable, except for the case
where there is chroma only combing in the source.
</p>
<p>Default value is <code>0</code>.
</p>
</dd>
<dt><samp>blockx</samp></dt>
<dt><samp>blocky</samp></dt>
<dd><p>Respectively set the x-axis and y-axis size of the window used during combed
frame detection. This has to do with the size of the area in which
<samp>combpel</samp> pixels are required to be detected as combed for a frame to be
declared combed. See the <samp>combpel</samp> parameter description for more info.
Possible values are any number that is a power of 2 starting at 4 and going up
to 512.
</p>
<p>Default value is <code>16</code>.
</p>
</dd>
<dt><samp>combpel</samp></dt>
<dd><p>The number of combed pixels inside any of the <samp>blocky</samp> by
<samp>blockx</samp> size blocks on the frame for the frame to be detected as
combed. While <samp>cthresh</samp> controls how "visible" the combing must be, this
setting controls "how much" combing there must be in any localized area (a
window defined by the <samp>blockx</samp> and <samp>blocky</samp> settings) on the
frame. Minimum value is <code>0</code> and maximum is <code>blocky x blockx</code> (at
which point no frames will ever be detected as combed). This setting is known
as <samp>MI</samp> in TFM/VFM vocabulary.
</p>
<p>Default value is <code>80</code>.
</p></dd>
</dl>
<a name="p_002fc_002fn_002fu_002fb-meaning"></a><a name="p_002fc_002fn_002fu_002fb-meaning-1"></a>
<h4 class="subsection">37.41.1 p/c/n/u/b meaning<span class="pull-right"><a class="anchor hidden-xs" href="#p_002fc_002fn_002fu_002fb-meaning-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-p_002fc_002fn_002fu_002fb-meaning-1" aria-hidden="true">TOC</a></span></h4>
<a name="p_002fc_002fn"></a>
<h4 class="subsubsection">37.41.1.1 p/c/n<span class="pull-right"><a class="anchor hidden-xs" href="#p_002fc_002fn" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-p_002fc_002fn" aria-hidden="true">TOC</a></span></h4>
<p>We assume the following telecined stream:
</p>
<div class="example">
<pre class="example">Top fields: 1 2 2 3 4
Bottom fields: 1 2 3 4 4
</pre></div>
<p>The numbers correspond to the progressive frame the fields relate to. Here, the
first two frames are progressive, the 3rd and 4th are combed, and so on.
</p>
<p>When <code>fieldmatch</code> is configured to run a matching from bottom
(<samp>field</samp>=<var>bottom</var>) this is how this input stream get transformed:
</p>
<div class="example">
<pre class="example">Input stream:
T 1 2 2 3 4
B 1 2 3 4 4 <-- matching reference
Matches: c c n n c
Output stream:
T 1 2 3 4 4
B 1 2 3 4 4
</pre></div>
<p>As a result of the field matching, we can see that some frames get duplicated.
To perform a complete inverse telecine, you need to rely on a decimation filter
after this operation. See for instance the <a href="#decimate">decimate</a> filter.
</p>
<p>The same operation now matching from top fields (<samp>field</samp>=<var>top</var>)
looks like this:
</p>
<div class="example">
<pre class="example">Input stream:
T 1 2 2 3 4 <-- matching reference
B 1 2 3 4 4
Matches: c c p p c
Output stream:
T 1 2 2 3 4
B 1 2 2 3 4
</pre></div>
<p>In these examples, we can see what <var>p</var>, <var>c</var> and <var>n</var> mean;
basically, they refer to the frame and field of the opposite parity:
</p>
<ul>
<li> <var>p</var> matches the field of the opposite parity in the previous frame
</li><li> <var>c</var> matches the field of the opposite parity in the current frame
</li><li> <var>n</var> matches the field of the opposite parity in the next frame
</li></ul>
<a name="u_002fb"></a>
<h4 class="subsubsection">37.41.1.2 u/b<span class="pull-right"><a class="anchor hidden-xs" href="#u_002fb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-u_002fb" aria-hidden="true">TOC</a></span></h4>
<p>The <var>u</var> and <var>b</var> matching are a bit special in the sense that they match
from the opposite parity flag. In the following examples, we assume that we are
currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
’x’ is placed above and below each matched fields.
</p>
<p>With bottom matching (<samp>field</samp>=<var>bottom</var>):
</p><div class="example">
<pre class="example">Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 1 2 2 2
2 2 2 1 3
</pre></div>
<p>With top matching (<samp>field</samp>=<var>top</var>):
</p><div class="example">
<pre class="example">Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 2 2 1 2
2 1 3 2 2
</pre></div>
<a name="Examples-71"></a>
<h4 class="subsection">37.41.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-71" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-71" aria-hidden="true">TOC</a></span></h4>
<p>Simple IVTC of a top field first telecined stream:
</p><div class="example">
<pre class="example">fieldmatch=order=tff:combmatch=none, decimate
</pre></div>
<p>Advanced IVTC, with fallback on <a href="#yadif">yadif</a> for still combed frames:
</p><div class="example">
<pre class="example">fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
</pre></div>
<a name="fieldorder"></a>
<h3 class="section">37.42 fieldorder<span class="pull-right"><a class="anchor hidden-xs" href="#fieldorder" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fieldorder" aria-hidden="true">TOC</a></span></h3>
<p>Transform the field order of the input video.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>order</samp></dt>
<dd><p>The output field order. Valid values are <var>tff</var> for top field first or <var>bff</var>
for bottom field first.
</p></dd>
</dl>
<p>The default value is ‘<samp>tff</samp>’.
</p>
<p>The transformation is done by shifting the picture content up or down
by one line, and filling the remaining line with appropriate picture content.
This method is consistent with most broadcast field order converters.
</p>
<p>If the input video is not flagged as being interlaced, or it is already
flagged as being of the required output field order, then this filter does
not alter the incoming video.
</p>
<p>It is very useful when converting to or from PAL DV material,
which is bottom field first.
</p>
<p>For example:
</p><div class="example">
<pre class="example">ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
</pre></div>
<a name="fifo"></a>
<h3 class="section">37.43 fifo<span class="pull-right"><a class="anchor hidden-xs" href="#fifo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fifo" aria-hidden="true">TOC</a></span></h3>
<p>Buffer input images and send them when they are requested.
</p>
<p>It is mainly useful when auto-inserted by the libavfilter
framework.
</p>
<p>It does not take parameters.
</p>
<a name="find_005frect"></a>
<h3 class="section">37.44 find_rect<span class="pull-right"><a class="anchor hidden-xs" href="#find_005frect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-find_005frect" aria-hidden="true">TOC</a></span></h3>
<p>Find a rectangular object
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>object</samp></dt>
<dd><p>Filepath of the object image, needs to be in gray8.
</p>
</dd>
<dt><samp>threshold</samp></dt>
<dd><p>Detection threshold, default is 0.5.
</p>
</dd>
<dt><samp>mipmaps</samp></dt>
<dd><p>Number of mipmaps, default is 3.
</p>
</dd>
<dt><samp>xmin, ymin, xmax, ymax</samp></dt>
<dd><p>Specifies the rectangle in which to search.
</p></dd>
</dl>
<a name="Examples-72"></a>
<h4 class="subsection">37.44.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-72" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-72" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Generate a representative palette of a given video using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
</pre></div>
</li></ul>
<a name="cover_005frect"></a>
<h3 class="section">37.45 cover_rect<span class="pull-right"><a class="anchor hidden-xs" href="#cover_005frect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-cover_005frect" aria-hidden="true">TOC</a></span></h3>
<p>Cover a rectangular object
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>cover</samp></dt>
<dd><p>Filepath of the optional cover image, needs to be in yuv420.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set covering mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>cover</samp>’</dt>
<dd><p>cover it by the supplied image
</p></dd>
<dt>‘<samp>blur</samp>’</dt>
<dd><p>cover it by interpolating the surrounding pixels
</p></dd>
</dl>
<p>Default value is <var>blur</var>.
</p></dd>
</dl>
<a name="Examples-73"></a>
<h4 class="subsection">37.45.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-73" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-73" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Generate a representative palette of a given video using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
</pre></div>
</li></ul>
<a name="format"></a><a name="format-1"></a>
<h3 class="section">37.46 format<span class="pull-right"><a class="anchor hidden-xs" href="#format-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-format-1" aria-hidden="true">TOC</a></span></h3>
<p>Convert the input video to one of the specified pixel formats.
Libavfilter will try to pick one that is suitable as input to
the next filter.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>pix_fmts</samp></dt>
<dd><p>A ’|’-separated list of pixel format names, such as
"pix_fmts=yuv420p|monow|rgb24".
</p>
</dd>
</dl>
<a name="Examples-74"></a>
<h4 class="subsection">37.46.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-74" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-74" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Convert the input video to the <var>yuv420p</var> format
<div class="example">
<pre class="example">format=pix_fmts=yuv420p
</pre></div>
<p>Convert the input video to any of the formats in the list
</p><div class="example">
<pre class="example">format=pix_fmts=yuv420p|yuv444p|yuv410p
</pre></div>
</li></ul>
<a name="fps"></a><a name="fps-1"></a>
<h3 class="section">37.47 fps<span class="pull-right"><a class="anchor hidden-xs" href="#fps-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fps-1" aria-hidden="true">TOC</a></span></h3>
<p>Convert the video to specified constant frame rate by duplicating or dropping
frames as necessary.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>fps</samp></dt>
<dd><p>The desired output frame rate. The default is <code>25</code>.
</p>
</dd>
<dt><samp>round</samp></dt>
<dd><p>Rounding method.
</p>
<p>Possible values are:
</p><dl compact="compact">
<dt><samp>zero</samp></dt>
<dd><p>zero round towards 0
</p></dd>
<dt><samp>inf</samp></dt>
<dd><p>round away from 0
</p></dd>
<dt><samp>down</samp></dt>
<dd><p>round towards -infinity
</p></dd>
<dt><samp>up</samp></dt>
<dd><p>round towards +infinity
</p></dd>
<dt><samp>near</samp></dt>
<dd><p>round to nearest
</p></dd>
</dl>
<p>The default is <code>near</code>.
</p>
</dd>
<dt><samp>start_time</samp></dt>
<dd><p>Assume the first PTS should be the given value, in seconds. This allows for
padding/trimming at the start of stream. By default, no assumption is made
about the first frame’s expected PTS, so no padding or trimming is done.
For example, this could be set to 0 to pad the beginning with duplicates of
the first frame if a video stream starts after the audio stream or to trim any
frames with a negative PTS.
</p>
</dd>
</dl>
<p>Alternatively, the options can be specified as a flat string:
<var>fps</var>[:<var>round</var>].
</p>
<p>See also the <a href="#setpts">setpts</a> filter.
</p>
<a name="Examples-75"></a>
<h4 class="subsection">37.47.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-75" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-75" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> A typical usage in order to set the fps to 25:
<div class="example">
<pre class="example">fps=fps=25
</pre></div>
</li><li> Sets the fps to 24, using abbreviation and rounding method to round to nearest:
<div class="example">
<pre class="example">fps=fps=film:round=near
</pre></div>
</li></ul>
<a name="framepack"></a>
<h3 class="section">37.48 framepack<span class="pull-right"><a class="anchor hidden-xs" href="#framepack" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-framepack" aria-hidden="true">TOC</a></span></h3>
<p>Pack two different video streams into a stereoscopic video, setting proper
metadata on supported codecs. The two views should have the same size and
framerate and processing will stop when the shorter video ends. Please note
that you may conveniently adjust view properties with the <a href="#scale">scale</a> and
<a href="#fps">fps</a> filters.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>format</samp></dt>
<dd><p>The desired packing format. Supported values are:
</p>
<dl compact="compact">
<dt><samp>sbs</samp></dt>
<dd><p>The views are next to each other (default).
</p>
</dd>
<dt><samp>tab</samp></dt>
<dd><p>The views are on top of each other.
</p>
</dd>
<dt><samp>lines</samp></dt>
<dd><p>The views are packed by line.
</p>
</dd>
<dt><samp>columns</samp></dt>
<dd><p>The views are packed by column.
</p>
</dd>
<dt><samp>frameseq</samp></dt>
<dd><p>The views are temporally interleaved.
</p>
</dd>
</dl>
</dd>
</dl>
<p>Some examples:
</p>
<div class="example">
<pre class="example"># Convert left and right views into a frame-sequential video
ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
# Convert views into a side-by-side video with the same output resolution as the input
ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
</pre></div>
<a name="framerate"></a>
<h3 class="section">37.49 framerate<span class="pull-right"><a class="anchor hidden-xs" href="#framerate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-framerate" aria-hidden="true">TOC</a></span></h3>
<p>Change the frame rate by interpolating new video output frames from the source
frames.
</p>
<p>This filter is not designed to function correctly with interlaced media. If
you wish to change the frame rate of interlaced media then you are required
to deinterlace before this filter and re-interlace after this filter.
</p>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>fps</samp></dt>
<dd><p>Specify the output frames per second. This option can also be specified
as a value alone. The default is <code>50</code>.
</p>
</dd>
<dt><samp>interp_start</samp></dt>
<dd><p>Specify the start of a range where the output frame will be created as a
linear interpolation of two frames. The range is [<code>0</code>-<code>255</code>],
the default is <code>15</code>.
</p>
</dd>
<dt><samp>interp_end</samp></dt>
<dd><p>Specify the end of a range where the output frame will be created as a
linear interpolation of two frames. The range is [<code>0</code>-<code>255</code>],
the default is <code>240</code>.
</p>
</dd>
<dt><samp>scene</samp></dt>
<dd><p>Specify the level at which a scene change is detected as a value between
0 and 100 to indicate a new scene; a low value reflects a low
probability for the current frame to introduce a new scene, while a higher
value means the current frame is more likely to be one.
The default is <code>7</code>.
</p>
</dd>
<dt><samp>flags</samp></dt>
<dd><p>Specify flags influencing the filter process.
</p>
<p>Available value for <var>flags</var> is:
</p>
<dl compact="compact">
<dt><samp>scene_change_detect, scd</samp></dt>
<dd><p>Enable scene change detection using the value of the option <var>scene</var>.
This flag is enabled by default.
</p></dd>
</dl>
</dd>
</dl>
<a name="framestep"></a>
<h3 class="section">37.50 framestep<span class="pull-right"><a class="anchor hidden-xs" href="#framestep" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-framestep" aria-hidden="true">TOC</a></span></h3>
<p>Select one frame every N-th frame.
</p>
<p>This filter accepts the following option:
</p><dl compact="compact">
<dt><samp>step</samp></dt>
<dd><p>Select frame after every <code>step</code> frames.
Allowed values are positive integers higher than 0. Default value is <code>1</code>.
</p></dd>
</dl>
<a name="frei0r"></a><a name="frei0r-1"></a>
<h3 class="section">37.51 frei0r<span class="pull-right"><a class="anchor hidden-xs" href="#frei0r-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-frei0r-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply a frei0r effect to the input video.
</p>
<p>To enable the compilation of this filter, you need to install the frei0r
header and configure FFmpeg with <code>--enable-frei0r</code>.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>filter_name</samp></dt>
<dd><p>The name of the frei0r effect to load. If the environment variable
<code>FREI0R_PATH</code> is defined, the frei0r effect is searched for in each of the
directories specified by the colon-separated list in <code>FREIOR_PATH</code>.
Otherwise, the standard frei0r paths are searched, in this order:
<samp>HOME/.frei0r-1/lib/</samp>, <samp>/usr/local/lib/frei0r-1/</samp>,
<samp>/usr/lib/frei0r-1/</samp>.
</p>
</dd>
<dt><samp>filter_params</samp></dt>
<dd><p>A ’|’-separated list of parameters to pass to the frei0r effect.
</p>
</dd>
</dl>
<p>A frei0r effect parameter can be a boolean (its value is either
"y" or "n"), a double, a color (specified as
<var>R</var>/<var>G</var>/<var>B</var>, where <var>R</var>, <var>G</var>, and <var>B</var> are floating point
numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
section in the ffmpeg-utils manual), a position (specified as <var>X</var>/<var>Y</var>, where
<var>X</var> and <var>Y</var> are floating point numbers) and/or a string.
</p>
<p>The number and types of parameters depend on the loaded effect. If an
effect parameter is not specified, the default value is set.
</p>
<a name="Examples-76"></a>
<h4 class="subsection">37.51.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-76" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-76" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply the distort0r effect, setting the first two double parameters:
<div class="example">
<pre class="example">frei0r=filter_name=distort0r:filter_params=0.5|0.01
</pre></div>
</li><li> Apply the colordistance effect, taking a color as the first parameter:
<div class="example">
<pre class="example">frei0r=colordistance:0.2/0.3/0.4
frei0r=colordistance:violet
frei0r=colordistance:0x112233
</pre></div>
</li><li> Apply the perspective effect, specifying the top left and top right image
positions:
<div class="example">
<pre class="example">frei0r=perspective:0.2/0.2|0.8/0.2
</pre></div>
</li></ul>
<p>For more information, see
<a href="http://frei0r.dyne.org">http://frei0r.dyne.org</a>
</p>
<a name="fspp"></a>
<h3 class="section">37.52 fspp<span class="pull-right"><a class="anchor hidden-xs" href="#fspp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-fspp" aria-hidden="true">TOC</a></span></h3>
<p>Apply fast and simple postprocessing. It is a faster version of <a href="#spp">spp</a>.
</p>
<p>It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
processing filter, one of them is performed once per block, not per pixel.
This allows for much higher speed.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>quality</samp></dt>
<dd><p>Set quality. This option defines the number of levels for averaging. It accepts
an integer in the range 4-5. Default value is <code>4</code>.
</p>
</dd>
<dt><samp>qp</samp></dt>
<dd><p>Force a constant quantization parameter. It accepts an integer in range 0-63.
If not set, the filter will use the QP from the video stream (if available).
</p>
</dd>
<dt><samp>strength</samp></dt>
<dd><p>Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
more details but also more artifacts, while higher values make the image smoother
but also blurrier. Default value is <code>0</code> − PSNR optimal.
</p>
</dd>
<dt><samp>use_bframe_qp</samp></dt>
<dd><p>Enable the use of the QP from the B-Frames if set to <code>1</code>. Using this
option may cause flicker since the B-Frames have often larger QP. Default is
<code>0</code> (not enabled).
</p>
</dd>
</dl>
<a name="geq"></a>
<h3 class="section">37.53 geq<span class="pull-right"><a class="anchor hidden-xs" href="#geq" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-geq" aria-hidden="true">TOC</a></span></h3>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>lum_expr, lum</samp></dt>
<dd><p>Set the luminance expression.
</p></dd>
<dt><samp>cb_expr, cb</samp></dt>
<dd><p>Set the chrominance blue expression.
</p></dd>
<dt><samp>cr_expr, cr</samp></dt>
<dd><p>Set the chrominance red expression.
</p></dd>
<dt><samp>alpha_expr, a</samp></dt>
<dd><p>Set the alpha expression.
</p></dd>
<dt><samp>red_expr, r</samp></dt>
<dd><p>Set the red expression.
</p></dd>
<dt><samp>green_expr, g</samp></dt>
<dd><p>Set the green expression.
</p></dd>
<dt><samp>blue_expr, b</samp></dt>
<dd><p>Set the blue expression.
</p></dd>
</dl>
<p>The colorspace is selected according to the specified options. If one
of the <samp>lum_expr</samp>, <samp>cb_expr</samp>, or <samp>cr_expr</samp>
options is specified, the filter will automatically select a YCbCr
colorspace. If one of the <samp>red_expr</samp>, <samp>green_expr</samp>, or
<samp>blue_expr</samp> options is specified, it will select an RGB
colorspace.
</p>
<p>If one of the chrominance expression is not defined, it falls back on the other
one. If no alpha expression is specified it will evaluate to opaque value.
If none of chrominance expressions are specified, they will evaluate
to the luminance expression.
</p>
<p>The expressions can use the following variables and functions:
</p>
<dl compact="compact">
<dt><samp>N</samp></dt>
<dd><p>The sequential number of the filtered frame, starting from <code>0</code>.
</p>
</dd>
<dt><samp>X</samp></dt>
<dt><samp>Y</samp></dt>
<dd><p>The coordinates of the current sample.
</p>
</dd>
<dt><samp>W</samp></dt>
<dt><samp>H</samp></dt>
<dd><p>The width and height of the image.
</p>
</dd>
<dt><samp>SW</samp></dt>
<dt><samp>SH</samp></dt>
<dd><p>Width and height scale depending on the currently filtered plane. It is the
ratio between the corresponding luma plane number of pixels and the current
plane ones. E.g. for YUV4:2:0 the values are <code>1,1</code> for the luma plane, and
<code>0.5,0.5</code> for chroma planes.
</p>
</dd>
<dt><samp>T</samp></dt>
<dd><p>Time of the current frame, expressed in seconds.
</p>
</dd>
<dt><samp>p(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the current
plane.
</p>
</dd>
<dt><samp>lum(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the luminance
plane.
</p>
</dd>
<dt><samp>cb(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the
blue-difference chroma plane. Return 0 if there is no such plane.
</p>
</dd>
<dt><samp>cr(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the
red-difference chroma plane. Return 0 if there is no such plane.
</p>
</dd>
<dt><samp>r(x, y)</samp></dt>
<dt><samp>g(x, y)</samp></dt>
<dt><samp>b(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the
red/green/blue component. Return 0 if there is no such component.
</p>
</dd>
<dt><samp>alpha(x, y)</samp></dt>
<dd><p>Return the value of the pixel at location (<var>x</var>,<var>y</var>) of the alpha
plane. Return 0 if there is no such plane.
</p></dd>
</dl>
<p>For functions, if <var>x</var> and <var>y</var> are outside the area, the value will be
automatically clipped to the closer edge.
</p>
<a name="Examples-77"></a>
<h4 class="subsection">37.53.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-77" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-77" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Flip the image horizontally:
<div class="example">
<pre class="example">geq=p(W-X\,Y)
</pre></div>
</li><li> Generate a bidimensional sine wave, with angle <code>PI/3</code> and a
wavelength of 100 pixels:
<div class="example">
<pre class="example">geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
</pre></div>
</li><li> Generate a fancy enigmatic moving light:
<div class="example">
<pre class="example">nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
</pre></div>
</li><li> Generate a quick emboss effect:
<div class="example">
<pre class="example">format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
</pre></div>
</li><li> Modify RGB components depending on pixel position:
<div class="example">
<pre class="example">geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
</pre></div>
</li><li> Create a radial gradient that is the same size as the input (also see
the <a href="#vignette">vignette</a> filter):
<div class="example">
<pre class="example">geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
</pre></div>
</li><li> Create a linear gradient to use as a mask for another filter, then
compose with <a href="#overlay">overlay</a>. In this example the video will gradually
become more blurry from the top to the bottom of the y-axis as defined
by the linear gradient:
<div class="example">
<pre class="example">ffmpeg -i input.mp4 -filter_complex "geq=lum=255*(Y/H),format=gray[grad];[0:v]boxblur=4[blur];[blur][grad]alphamerge[alpha];[0:v][alpha]overlay" output.mp4
</pre></div>
</li></ul>
<a name="gradfun"></a>
<h3 class="section">37.54 gradfun<span class="pull-right"><a class="anchor hidden-xs" href="#gradfun" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-gradfun" aria-hidden="true">TOC</a></span></h3>
<p>Fix the banding artifacts that are sometimes introduced into nearly flat
regions by truncation to 8bit color depth.
Interpolate the gradients that should go where the bands are, and
dither them.
</p>
<p>It is designed for playback only. Do not use it prior to
lossy compression, because compression tends to lose the dither and
bring back the bands.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>strength</samp></dt>
<dd><p>The maximum amount by which the filter will change any one pixel. This is also
the threshold for detecting nearly flat regions. Acceptable values range from
.51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
valid range.
</p>
</dd>
<dt><samp>radius</samp></dt>
<dd><p>The neighborhood to fit the gradient to. A larger radius makes for smoother
gradients, but also prevents the filter from modifying the pixels near detailed
regions. Acceptable values are 8-32; the default value is 16. Out-of-range
values will be clipped to the valid range.
</p>
</dd>
</dl>
<p>Alternatively, the options can be specified as a flat string:
<var>strength</var>[:<var>radius</var>]
</p>
<a name="Examples-78"></a>
<h4 class="subsection">37.54.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-78" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-78" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply the filter with a <code>3.5</code> strength and radius of <code>8</code>:
<div class="example">
<pre class="example">gradfun=3.5:8
</pre></div>
</li><li> Specify radius, omitting the strength (which will fall-back to the default
value):
<div class="example">
<pre class="example">gradfun=radius=8
</pre></div>
</li></ul>
<a name="haldclut"></a><a name="haldclut-1"></a>
<h3 class="section">37.55 haldclut<span class="pull-right"><a class="anchor hidden-xs" href="#haldclut-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-haldclut-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply a Hald CLUT to a video stream.
</p>
<p>First input is the video stream to process, and second one is the Hald CLUT.
The Hald CLUT input can be a simple picture or a complete video stream.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>shortest</samp></dt>
<dd><p>Force termination when the shortest input terminates. Default is <code>0</code>.
</p></dd>
<dt><samp>repeatlast</samp></dt>
<dd><p>Continue applying the last CLUT after the end of the stream. A value of
<code>0</code> disable the filter after the last frame of the CLUT is reached.
Default is <code>1</code>.
</p></dd>
</dl>
<p><code>haldclut</code> also has the same interpolation options as <a href="#lut3d">lut3d</a> (both
filters share the same internals).
</p>
<p>More information about the Hald CLUT can be found on Eskil Steenberg’s website
(Hald CLUT author) at <a href="http://www.quelsolaar.com/technology/clut.html">http://www.quelsolaar.com/technology/clut.html</a>.
</p>
<a name="Workflow-examples"></a>
<h4 class="subsection">37.55.1 Workflow examples<span class="pull-right"><a class="anchor hidden-xs" href="#Workflow-examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Workflow-examples" aria-hidden="true">TOC</a></span></h4>
<a name="Hald-CLUT-video-stream"></a>
<h4 class="subsubsection">37.55.1.1 Hald CLUT video stream<span class="pull-right"><a class="anchor hidden-xs" href="#Hald-CLUT-video-stream" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Hald-CLUT-video-stream" aria-hidden="true">TOC</a></span></h4>
<p>Generate an identity Hald CLUT stream altered with various effects:
</p><div class="example">
<pre class="example">ffmpeg -f lavfi -i <a href="#haldclutsrc">haldclutsrc</a>=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
</pre></div>
<p>Note: make sure you use a lossless codec.
</p>
<p>Then use it with <code>haldclut</code> to apply it on some random stream:
</p><div class="example">
<pre class="example">ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
</pre></div>
<p>The Hald CLUT will be applied to the 10 first seconds (duration of
<samp>clut.nut</samp>), then the latest picture of that CLUT stream will be applied
to the remaining frames of the <code>mandelbrot</code> stream.
</p>
<a name="Hald-CLUT-with-preview"></a>
<h4 class="subsubsection">37.55.1.2 Hald CLUT with preview<span class="pull-right"><a class="anchor hidden-xs" href="#Hald-CLUT-with-preview" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Hald-CLUT-with-preview" aria-hidden="true">TOC</a></span></h4>
<p>A Hald CLUT is supposed to be a squared image of <code>Level*Level*Level</code> by
<code>Level*Level*Level</code> pixels. For a given Hald CLUT, FFmpeg will select the
biggest possible square starting at the top left of the picture. The remaining
padding pixels (bottom or right) will be ignored. This area can be used to add
a preview of the Hald CLUT.
</p>
<p>Typically, the following generated Hald CLUT will be supported by the
<code>haldclut</code> filter:
</p>
<div class="example">
<pre class="example">ffmpeg -f lavfi -i <a href="#haldclutsrc">haldclutsrc</a>=8 -vf "
pad=iw+320 [padded_clut];
smptebars=s=320x256, split [a][b];
[padded_clut][a] overlay=W-320:h, curves=color_negative [main];
[main][b] overlay=W-320" -frames:v 1 clut.png
</pre></div>
<p>It contains the original and a preview of the effect of the CLUT: SMPTE color
bars are displayed on the right-top, and below the same color bars processed by
the color changes.
</p>
<p>Then, the effect of this Hald CLUT can be visualized with:
</p><div class="example">
<pre class="example">ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
</pre></div>
<a name="hflip"></a>
<h3 class="section">37.56 hflip<span class="pull-right"><a class="anchor hidden-xs" href="#hflip" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hflip" aria-hidden="true">TOC</a></span></h3>
<p>Flip the input video horizontally.
</p>
<p>For example, to horizontally flip the input video with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i in.avi -vf "hflip" out.avi
</pre></div>
<a name="histeq"></a>
<h3 class="section">37.57 histeq<span class="pull-right"><a class="anchor hidden-xs" href="#histeq" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-histeq" aria-hidden="true">TOC</a></span></h3>
<p>This filter applies a global color histogram equalization on a
per-frame basis.
</p>
<p>It can be used to correct video that has a compressed range of pixel
intensities. The filter redistributes the pixel intensities to
equalize their distribution across the intensity range. It may be
viewed as an "automatically adjusting contrast filter". This filter is
useful only for correcting degraded or poorly captured source
video.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>strength</samp></dt>
<dd><p>Determine the amount of equalization to be applied. As the strength
is reduced, the distribution of pixel intensities more-and-more
approaches that of the input frame. The value must be a float number
in the range [0,1] and defaults to 0.200.
</p>
</dd>
<dt><samp>intensity</samp></dt>
<dd><p>Set the maximum intensity that can generated and scale the output
values appropriately. The strength should be set as desired and then
the intensity can be limited if needed to avoid washing-out. The value
must be a float number in the range [0,1] and defaults to 0.210.
</p>
</dd>
<dt><samp>antibanding</samp></dt>
<dd><p>Set the antibanding level. If enabled the filter will randomly vary
the luminance of output pixels by a small amount to avoid banding of
the histogram. Possible values are <code>none</code>, <code>weak</code> or
<code>strong</code>. It defaults to <code>none</code>.
</p></dd>
</dl>
<a name="histogram"></a>
<h3 class="section">37.58 histogram<span class="pull-right"><a class="anchor hidden-xs" href="#histogram" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-histogram" aria-hidden="true">TOC</a></span></h3>
<p>Compute and draw a color distribution histogram for the input video.
</p>
<p>The computed histogram is a representation of the color component
distribution in an image.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Set histogram mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>levels</samp>’</dt>
<dd><p>Standard histogram that displays the color components distribution in an
image. Displays color graph for each color component. Shows distribution of
the Y, U, V, A or R, G, B components, depending on input format, in the
current frame. Below each graph a color component scale meter is shown.
</p>
</dd>
<dt>‘<samp>color</samp>’</dt>
<dd><p>Displays chroma values (U/V color placement) in a two dimensional
graph (which is called a vectorscope). The brighter a pixel in the
vectorscope, the more pixels of the input frame correspond to that pixel
(i.e., more pixels have this chroma value). The V component is displayed on
the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
side being V = 255. The U component is displayed on the vertical (Y) axis,
with the top representing U = 0 and the bottom representing U = 255.
</p>
<p>The position of a white pixel in the graph corresponds to the chroma value of
a pixel of the input clip. The graph can therefore be used to read the hue
(color flavor) and the saturation (the dominance of the hue in the color). As
the hue of a color changes, it moves around the square. At the center of the
square the saturation is zero, which means that the corresponding pixel has no
color. If the amount of a specific color is increased (while leaving the other
colors unchanged) the saturation increases, and the indicator moves towards
the edge of the square.
</p>
</dd>
<dt>‘<samp>color2</samp>’</dt>
<dd><p>Chroma values in vectorscope, similar as <code>color</code> but actual chroma values
are displayed.
</p>
</dd>
<dt>‘<samp>waveform</samp>’</dt>
<dd><p>Per row/column color component graph. In row mode, the graph on the left side
represents color component value 0 and the right side represents value = 255.
In column mode, the top side represents color component value = 0 and bottom
side represents value = 255.
</p></dd>
</dl>
<p>Default value is <code>levels</code>.
</p>
</dd>
<dt><samp>level_height</samp></dt>
<dd><p>Set height of level in <code>levels</code>. Default value is <code>200</code>.
Allowed range is [50, 2048].
</p>
</dd>
<dt><samp>scale_height</samp></dt>
<dd><p>Set height of color scale in <code>levels</code>. Default value is <code>12</code>.
Allowed range is [0, 40].
</p>
</dd>
<dt><samp>step</samp></dt>
<dd><p>Set step for <code>waveform</code> mode. Smaller values are useful to find out how
many values of the same luminance are distributed across input rows/columns.
Default value is <code>10</code>. Allowed range is [1, 255].
</p>
</dd>
<dt><samp>waveform_mode</samp></dt>
<dd><p>Set mode for <code>waveform</code>. Can be either <code>row</code>, or <code>column</code>.
Default is <code>row</code>.
</p>
</dd>
<dt><samp>waveform_mirror</samp></dt>
<dd><p>Set mirroring mode for <code>waveform</code>. <code>0</code> means unmirrored, <code>1</code>
means mirrored. In mirrored mode, higher values will be represented on the left
side for <code>row</code> mode and at the top for <code>column</code> mode. Default is
<code>0</code> (unmirrored).
</p>
</dd>
<dt><samp>display_mode</samp></dt>
<dd><p>Set display mode for <code>waveform</code> and <code>levels</code>.
It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>parade</samp>’</dt>
<dd><p>Display separate graph for the color components side by side in
<code>row</code> waveform mode or one below the other in <code>column</code> waveform mode
for <code>waveform</code> histogram mode. For <code>levels</code> histogram mode,
per color component graphs are placed below each other.
</p>
<p>Using this display mode in <code>waveform</code> histogram mode makes it easy to
spot color casts in the highlights and shadows of an image, by comparing the
contours of the top and the bottom graphs of each waveform. Since whites,
grays, and blacks are characterized by exactly equal amounts of red, green,
and blue, neutral areas of the picture should display three waveforms of
roughly equal width/height. If not, the correction is easy to perform by
making level adjustments the three waveforms.
</p>
</dd>
<dt>‘<samp>overlay</samp>’</dt>
<dd><p>Presents information identical to that in the <code>parade</code>, except
that the graphs representing color components are superimposed directly
over one another.
</p>
<p>This display mode in <code>waveform</code> histogram mode makes it easier to spot
relative differences or similarities in overlapping areas of the color
components that are supposed to be identical, such as neutral whites, grays,
or blacks.
</p></dd>
</dl>
<p>Default is <code>parade</code>.
</p>
</dd>
<dt><samp>levels_mode</samp></dt>
<dd><p>Set mode for <code>levels</code>. Can be either <code>linear</code>, or <code>logarithmic</code>.
Default is <code>linear</code>.
</p>
</dd>
<dt><samp>components</samp></dt>
<dd><p>Set what color components to display for mode <code>levels</code>.
Default is <code>7</code>.
</p></dd>
</dl>
<a name="Examples-79"></a>
<h4 class="subsection">37.58.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-79" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-79" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Calculate and draw histogram:
<div class="example">
<pre class="example">ffplay -i input -vf histogram
</pre></div>
</li></ul>
<a name="hqdn3d"></a><a name="hqdn3d-1"></a>
<h3 class="section">37.59 hqdn3d<span class="pull-right"><a class="anchor hidden-xs" href="#hqdn3d-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hqdn3d-1" aria-hidden="true">TOC</a></span></h3>
<p>This is a high precision/quality 3d denoise filter. It aims to reduce
image noise, producing smooth images and making still images really
still. It should enhance compressibility.
</p>
<p>It accepts the following optional parameters:
</p>
<dl compact="compact">
<dt><samp>luma_spatial</samp></dt>
<dd><p>A non-negative floating point number which specifies spatial luma strength.
It defaults to 4.0.
</p>
</dd>
<dt><samp>chroma_spatial</samp></dt>
<dd><p>A non-negative floating point number which specifies spatial chroma strength.
It defaults to 3.0*<var>luma_spatial</var>/4.0.
</p>
</dd>
<dt><samp>luma_tmp</samp></dt>
<dd><p>A floating point number which specifies luma temporal strength. It defaults to
6.0*<var>luma_spatial</var>/4.0.
</p>
</dd>
<dt><samp>chroma_tmp</samp></dt>
<dd><p>A floating point number which specifies chroma temporal strength. It defaults to
<var>luma_tmp</var>*<var>chroma_spatial</var>/<var>luma_spatial</var>.
</p></dd>
</dl>
<a name="hqx"></a>
<h3 class="section">37.60 hqx<span class="pull-right"><a class="anchor hidden-xs" href="#hqx" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hqx" aria-hidden="true">TOC</a></span></h3>
<p>Apply a high-quality magnification filter designed for pixel art. This filter
was originally created by Maxim Stepin.
</p>
<p>It accepts the following option:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>Set the scaling dimension: <code>2</code> for <code>hq2x</code>, <code>3</code> for
<code>hq3x</code> and <code>4</code> for <code>hq4x</code>.
Default is <code>3</code>.
</p></dd>
</dl>
<a name="hstack"></a>
<h3 class="section">37.61 hstack<span class="pull-right"><a class="anchor hidden-xs" href="#hstack" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hstack" aria-hidden="true">TOC</a></span></h3>
<p>Stack input videos horizontally.
</p>
<p>All streams must be of same pixel format and of same height.
</p>
<p>Note that this filter is faster than using <a href="#overlay">overlay</a> and <a href="#pad">pad</a> filter
to create same output.
</p>
<p>The filter accept the following option:
</p>
<dl compact="compact">
<dt><samp>nb_inputs</samp></dt>
<dd><p>Set number of input streams. Default is 2.
</p></dd>
</dl>
<a name="hue"></a>
<h3 class="section">37.62 hue<span class="pull-right"><a class="anchor hidden-xs" href="#hue" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-hue" aria-hidden="true">TOC</a></span></h3>
<p>Modify the hue and/or the saturation of the input.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>h</samp></dt>
<dd><p>Specify the hue angle as a number of degrees. It accepts an expression,
and defaults to "0".
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>Specify the saturation in the [-10,10] range. It accepts an expression and
defaults to "1".
</p>
</dd>
<dt><samp>H</samp></dt>
<dd><p>Specify the hue angle as a number of radians. It accepts an
expression, and defaults to "0".
</p>
</dd>
<dt><samp>b</samp></dt>
<dd><p>Specify the brightness in the [-10,10] range. It accepts an expression and
defaults to "0".
</p></dd>
</dl>
<p><samp>h</samp> and <samp>H</samp> are mutually exclusive, and can’t be
specified at the same time.
</p>
<p>The <samp>b</samp>, <samp>h</samp>, <samp>H</samp> and <samp>s</samp> option values are
expressions containing the following constants:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>frame count of the input frame starting from 0
</p>
</dd>
<dt><samp>pts</samp></dt>
<dd><p>presentation timestamp of the input frame expressed in time base units
</p>
</dd>
<dt><samp>r</samp></dt>
<dd><p>frame rate of the input video, NAN if the input frame rate is unknown
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>timestamp expressed in seconds, NAN if the input timestamp is unknown
</p>
</dd>
<dt><samp>tb</samp></dt>
<dd><p>time base of the input video
</p></dd>
</dl>
<a name="Examples-80"></a>
<h4 class="subsection">37.62.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-80" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-80" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Set the hue to 90 degrees and the saturation to 1.0:
<div class="example">
<pre class="example">hue=h=90:s=1
</pre></div>
</li><li> Same command but expressing the hue in radians:
<div class="example">
<pre class="example">hue=H=PI/2:s=1
</pre></div>
</li><li> Rotate hue and make the saturation swing between 0
and 2 over a period of 1 second:
<div class="example">
<pre class="example">hue="H=2*PI*t: s=sin(2*PI*t)+1"
</pre></div>
</li><li> Apply a 3 seconds saturation fade-in effect starting at 0:
<div class="example">
<pre class="example">hue="s=min(t/3\,1)"
</pre></div>
<p>The general fade-in expression can be written as:
</p><div class="example">
<pre class="example">hue="s=min(0\, max((t-START)/DURATION\, 1))"
</pre></div>
</li><li> Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
<div class="example">
<pre class="example">hue="s=max(0\, min(1\, (8-t)/3))"
</pre></div>
<p>The general fade-out expression can be written as:
</p><div class="example">
<pre class="example">hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
</pre></div>
</li></ul>
<a name="Commands-4"></a>
<h4 class="subsection">37.62.2 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-4" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-4" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>b</samp></dt>
<dt><samp>s</samp></dt>
<dt><samp>h</samp></dt>
<dt><samp>H</samp></dt>
<dd><p>Modify the hue and/or the saturation and/or brightness of the input video.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
</dl>
<a name="idet"></a>
<h3 class="section">37.63 idet<span class="pull-right"><a class="anchor hidden-xs" href="#idet" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-idet" aria-hidden="true">TOC</a></span></h3>
<p>Detect video interlacing type.
</p>
<p>This filter tries to detect if the input frames as interlaced, progressive,
top or bottom field first. It will also try and detect fields that are
repeated between adjacent frames (a sign of telecine).
</p>
<p>Single frame detection considers only immediately adjacent frames when classifying each frame.
Multiple frame detection incorporates the classification history of previous frames.
</p>
<p>The filter will log these metadata values:
</p>
<dl compact="compact">
<dt><samp>single.current_frame</samp></dt>
<dd><p>Detected type of current frame using single-frame detection. One of:
“tff” (top field first), “bff” (bottom field first),
“progressive”, or “undetermined”
</p>
</dd>
<dt><samp>single.tff</samp></dt>
<dd><p>Cumulative number of frames detected as top field first using single-frame detection.
</p>
</dd>
<dt><samp>multiple.tff</samp></dt>
<dd><p>Cumulative number of frames detected as top field first using multiple-frame detection.
</p>
</dd>
<dt><samp>single.bff</samp></dt>
<dd><p>Cumulative number of frames detected as bottom field first using single-frame detection.
</p>
</dd>
<dt><samp>multiple.current_frame</samp></dt>
<dd><p>Detected type of current frame using multiple-frame detection. One of:
“tff” (top field first), “bff” (bottom field first),
“progressive”, or “undetermined”
</p>
</dd>
<dt><samp>multiple.bff</samp></dt>
<dd><p>Cumulative number of frames detected as bottom field first using multiple-frame detection.
</p>
</dd>
<dt><samp>single.progressive</samp></dt>
<dd><p>Cumulative number of frames detected as progressive using single-frame detection.
</p>
</dd>
<dt><samp>multiple.progressive</samp></dt>
<dd><p>Cumulative number of frames detected as progressive using multiple-frame detection.
</p>
</dd>
<dt><samp>single.undetermined</samp></dt>
<dd><p>Cumulative number of frames that could not be classified using single-frame detection.
</p>
</dd>
<dt><samp>multiple.undetermined</samp></dt>
<dd><p>Cumulative number of frames that could not be classified using multiple-frame detection.
</p>
</dd>
<dt><samp>repeated.current_frame</samp></dt>
<dd><p>Which field in the current frame is repeated from the last. One of “neither”, “top”, or “bottom”.
</p>
</dd>
<dt><samp>repeated.neither</samp></dt>
<dd><p>Cumulative number of frames with no repeated field.
</p>
</dd>
<dt><samp>repeated.top</samp></dt>
<dd><p>Cumulative number of frames with the top field repeated from the previous frame’s top field.
</p>
</dd>
<dt><samp>repeated.bottom</samp></dt>
<dd><p>Cumulative number of frames with the bottom field repeated from the previous frame’s bottom field.
</p></dd>
</dl>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>intl_thres</samp></dt>
<dd><p>Set interlacing threshold.
</p></dd>
<dt><samp>prog_thres</samp></dt>
<dd><p>Set progressive threshold.
</p></dd>
<dt><samp>repeat_thres</samp></dt>
<dd><p>Threshold for repeated field detection.
</p></dd>
<dt><samp>half_life</samp></dt>
<dd><p>Number of frames after which a given frame’s contribution to the
statistics is halved (i.e., it contributes only 0.5 to it’s
classification). The default of 0 means that all frames seen are given
full weight of 1.0 forever.
</p></dd>
<dt><samp>analyze_interlaced_flag</samp></dt>
<dd><p>When this is not 0 then idet will use the specified number of frames to determine
if the interlaced flag is accurate, it will not count undetermined frames.
If the flag is found to be accurate it will be used without any further
computations, if it is found to be inaccurate it will be cleared without any
further computations. This allows inserting the idet filter as a low computational
method to clean up the interlaced flag
</p></dd>
</dl>
<a name="il"></a>
<h3 class="section">37.64 il<span class="pull-right"><a class="anchor hidden-xs" href="#il" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-il" aria-hidden="true">TOC</a></span></h3>
<p>Deinterleave or interleave fields.
</p>
<p>This filter allows one to process interlaced images fields without
deinterlacing them. Deinterleaving splits the input frame into 2
fields (so called half pictures). Odd lines are moved to the top
half of the output image, even lines to the bottom half.
You can process (filter) them independently and then re-interleave them.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>luma_mode, l</samp></dt>
<dt><samp>chroma_mode, c</samp></dt>
<dt><samp>alpha_mode, a</samp></dt>
<dd><p>Available values for <var>luma_mode</var>, <var>chroma_mode</var> and
<var>alpha_mode</var> are:
</p>
<dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>Do nothing.
</p>
</dd>
<dt>‘<samp>deinterleave, d</samp>’</dt>
<dd><p>Deinterleave fields, placing one above the other.
</p>
</dd>
<dt>‘<samp>interleave, i</samp>’</dt>
<dd><p>Interleave fields. Reverse the effect of deinterleaving.
</p></dd>
</dl>
<p>Default value is <code>none</code>.
</p>
</dd>
<dt><samp>luma_swap, ls</samp></dt>
<dt><samp>chroma_swap, cs</samp></dt>
<dt><samp>alpha_swap, as</samp></dt>
<dd><p>Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is <code>0</code>.
</p></dd>
</dl>
<a name="inflate"></a>
<h3 class="section">37.65 inflate<span class="pull-right"><a class="anchor hidden-xs" href="#inflate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-inflate" aria-hidden="true">TOC</a></span></h3>
<p>Apply inflate effect to the video.
</p>
<p>This filter replaces the pixel by the local(3x3) average by taking into account
only values higher than the pixel.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>threshold0</samp></dt>
<dt><samp>threshold1</samp></dt>
<dt><samp>threshold2</samp></dt>
<dt><samp>threshold3</samp></dt>
<dd><p>Limit the maximum change for each plane, default is 65535.
If 0, plane will remain unchanged.
</p></dd>
</dl>
<a name="interlace"></a>
<h3 class="section">37.66 interlace<span class="pull-right"><a class="anchor hidden-xs" href="#interlace" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-interlace" aria-hidden="true">TOC</a></span></h3>
<p>Simple interlacing filter from progressive contents. This interleaves upper (or
lower) lines from odd frames with lower (or upper) lines from even frames,
halving the frame rate and preserving image height.
</p>
<div class="example">
<pre class="example"> Original Original New Frame
Frame 'j' Frame 'j+1' (tff)
========== =========== ==================
Line 0 --------------------> Frame 'j' Line 0
Line 1 Line 1 ----> Frame 'j+1' Line 1
Line 2 ---------------------> Frame 'j' Line 2
Line 3 Line 3 ----> Frame 'j+1' Line 3
... ... ...
New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
</pre></div>
<p>It accepts the following optional parameters:
</p>
<dl compact="compact">
<dt><samp>scan</samp></dt>
<dd><p>This determines whether the interlaced frame is taken from the even
(tff - default) or odd (bff) lines of the progressive frame.
</p>
</dd>
<dt><samp>lowpass</samp></dt>
<dd><p>Enable (default) or disable the vertical lowpass filter to avoid twitter
interlacing and reduce moire patterns.
</p></dd>
</dl>
<a name="kerndeint"></a>
<h3 class="section">37.67 kerndeint<span class="pull-right"><a class="anchor hidden-xs" href="#kerndeint" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-kerndeint" aria-hidden="true">TOC</a></span></h3>
<p>Deinterlace input video by applying Donald Graft’s adaptive kernel
deinterling. Work on interlaced parts of a video to produce
progressive frames.
</p>
<p>The description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>thresh</samp></dt>
<dd><p>Set the threshold which affects the filter’s tolerance when
determining if a pixel line must be processed. It must be an integer
in the range [0,255] and defaults to 10. A value of 0 will result in
applying the process on every pixels.
</p>
</dd>
<dt><samp>map</samp></dt>
<dd><p>Paint pixels exceeding the threshold value to white if set to 1.
Default is 0.
</p>
</dd>
<dt><samp>order</samp></dt>
<dd><p>Set the fields order. Swap fields if set to 1, leave fields alone if
0. Default is 0.
</p>
</dd>
<dt><samp>sharp</samp></dt>
<dd><p>Enable additional sharpening if set to 1. Default is 0.
</p>
</dd>
<dt><samp>twoway</samp></dt>
<dd><p>Enable twoway sharpening if set to 1. Default is 0.
</p></dd>
</dl>
<a name="Examples-81"></a>
<h4 class="subsection">37.67.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-81" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-81" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply default values:
<div class="example">
<pre class="example">kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
</pre></div>
</li><li> Enable additional sharpening:
<div class="example">
<pre class="example">kerndeint=sharp=1
</pre></div>
</li><li> Paint processed pixels in white:
<div class="example">
<pre class="example">kerndeint=map=1
</pre></div>
</li></ul>
<a name="lenscorrection"></a>
<h3 class="section">37.68 lenscorrection<span class="pull-right"><a class="anchor hidden-xs" href="#lenscorrection" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-lenscorrection" aria-hidden="true">TOC</a></span></h3>
<p>Correct radial lens distortion
</p>
<p>This filter can be used to correct for radial distortion as can result from the use
of wide angle lenses, and thereby re-rectify the image. To find the right parameters
one can use tools available for example as part of opencv or simply trial-and-error.
To use opencv use the calibration sample (under samples/cpp) from the opencv sources
and extract the k1 and k2 coefficients from the resulting matrix.
</p>
<p>Note that effectively the same filter is available in the open-source tools Krita and
Digikam from the KDE project.
</p>
<p>In contrast to the <a href="#vignette">vignette</a> filter, which can also be used to compensate lens errors,
this filter corrects the distortion of the image, whereas <a href="#vignette">vignette</a> corrects the
brightness distribution, so you may want to use both filters together in certain
cases, though you will have to take care of ordering, i.e. whether vignetting should
be applied before or after lens correction.
</p>
<a name="Options-68"></a>
<h4 class="subsection">37.68.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-68" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-68" aria-hidden="true">TOC</a></span></h4>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>cx</samp></dt>
<dd><p>Relative x-coordinate of the focal point of the image, and thereby the center of the
distortion. This value has a range [0,1] and is expressed as fractions of the image
width.
</p></dd>
<dt><samp>cy</samp></dt>
<dd><p>Relative y-coordinate of the focal point of the image, and thereby the center of the
distortion. This value has a range [0,1] and is expressed as fractions of the image
height.
</p></dd>
<dt><samp>k1</samp></dt>
<dd><p>Coefficient of the quadratic correction term. 0.5 means no correction.
</p></dd>
<dt><samp>k2</samp></dt>
<dd><p>Coefficient of the double quadratic correction term. 0.5 means no correction.
</p></dd>
</dl>
<p>The formula that generates the correction is:
</p>
<p><var>r_src</var> = <var>r_tgt</var> * (1 + <var>k1</var> * (<var>r_tgt</var> / <var>r_0</var>)^2 + <var>k2</var> * (<var>r_tgt</var> / <var>r_0</var>)^4)
</p>
<p>where <var>r_0</var> is halve of the image diagonal and <var>r_src</var> and <var>r_tgt</var> are the
distances from the focal point in the source and target images, respectively.
</p>
<a name="lut3d"></a><a name="lut3d-1"></a>
<h3 class="section">37.69 lut3d<span class="pull-right"><a class="anchor hidden-xs" href="#lut3d-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-lut3d-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply a 3D LUT to an input video.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>file</samp></dt>
<dd><p>Set the 3D LUT file name.
</p>
<p>Currently supported formats:
</p><dl compact="compact">
<dt>‘<samp>3dl</samp>’</dt>
<dd><p>AfterEffects
</p></dd>
<dt>‘<samp>cube</samp>’</dt>
<dd><p>Iridas
</p></dd>
<dt>‘<samp>dat</samp>’</dt>
<dd><p>DaVinci
</p></dd>
<dt>‘<samp>m3d</samp>’</dt>
<dd><p>Pandora
</p></dd>
</dl>
</dd>
<dt><samp>interp</samp></dt>
<dd><p>Select interpolation mode.
</p>
<p>Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>nearest</samp>’</dt>
<dd><p>Use values from the nearest defined point.
</p></dd>
<dt>‘<samp>trilinear</samp>’</dt>
<dd><p>Interpolate values using the 8 points defining a cube.
</p></dd>
<dt>‘<samp>tetrahedral</samp>’</dt>
<dd><p>Interpolate values using a tetrahedron.
</p></dd>
</dl>
</dd>
</dl>
<a name="lut_002c-lutrgb_002c-lutyuv"></a>
<h3 class="section">37.70 lut, lutrgb, lutyuv<span class="pull-right"><a class="anchor hidden-xs" href="#lut_002c-lutrgb_002c-lutyuv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-lut_002c-lutrgb_002c-lutyuv" aria-hidden="true">TOC</a></span></h3>
<p>Compute a look-up table for binding each pixel component input value
to an output value, and apply it to the input video.
</p>
<p><var>lutyuv</var> applies a lookup table to a YUV input video, <var>lutrgb</var>
to an RGB input video.
</p>
<p>These filters accept the following parameters:
</p><dl compact="compact">
<dt><samp>c0</samp></dt>
<dd><p>set first pixel component expression
</p></dd>
<dt><samp>c1</samp></dt>
<dd><p>set second pixel component expression
</p></dd>
<dt><samp>c2</samp></dt>
<dd><p>set third pixel component expression
</p></dd>
<dt><samp>c3</samp></dt>
<dd><p>set fourth pixel component expression, corresponds to the alpha component
</p>
</dd>
<dt><samp>r</samp></dt>
<dd><p>set red component expression
</p></dd>
<dt><samp>g</samp></dt>
<dd><p>set green component expression
</p></dd>
<dt><samp>b</samp></dt>
<dd><p>set blue component expression
</p></dd>
<dt><samp>a</samp></dt>
<dd><p>alpha component expression
</p>
</dd>
<dt><samp>y</samp></dt>
<dd><p>set Y/luminance component expression
</p></dd>
<dt><samp>u</samp></dt>
<dd><p>set U/Cb component expression
</p></dd>
<dt><samp>v</samp></dt>
<dd><p>set V/Cr component expression
</p></dd>
</dl>
<p>Each of them specifies the expression to use for computing the lookup table for
the corresponding pixel component values.
</p>
<p>The exact component associated to each of the <var>c*</var> options depends on the
format in input.
</p>
<p>The <var>lut</var> filter requires either YUV or RGB pixel formats in input,
<var>lutrgb</var> requires RGB pixel formats in input, and <var>lutyuv</var> requires YUV.
</p>
<p>The expressions can contain the following constants and functions:
</p>
<dl compact="compact">
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>The input width and height.
</p>
</dd>
<dt><samp>val</samp></dt>
<dd><p>The input value for the pixel component.
</p>
</dd>
<dt><samp>clipval</samp></dt>
<dd><p>The input value, clipped to the <var>minval</var>-<var>maxval</var> range.
</p>
</dd>
<dt><samp>maxval</samp></dt>
<dd><p>The maximum value for the pixel component.
</p>
</dd>
<dt><samp>minval</samp></dt>
<dd><p>The minimum value for the pixel component.
</p>
</dd>
<dt><samp>negval</samp></dt>
<dd><p>The negated value for the pixel component value, clipped to the
<var>minval</var>-<var>maxval</var> range; it corresponds to the expression
"maxval-clipval+minval".
</p>
</dd>
<dt><samp>clip(val)</samp></dt>
<dd><p>The computed value in <var>val</var>, clipped to the
<var>minval</var>-<var>maxval</var> range.
</p>
</dd>
<dt><samp>gammaval(gamma)</samp></dt>
<dd><p>The computed gamma correction value of the pixel component value,
clipped to the <var>minval</var>-<var>maxval</var> range. It corresponds to the
expression
"pow((clipval-minval)/(maxval-minval)\,<var>gamma</var>)*(maxval-minval)+minval"
</p>
</dd>
</dl>
<p>All expressions default to "val".
</p>
<a name="Examples-82"></a>
<h4 class="subsection">37.70.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-82" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-82" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Negate input video:
<div class="example">
<pre class="example">lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
</pre></div>
<p>The above is the same as:
</p><div class="example">
<pre class="example">lutrgb="r=negval:g=negval:b=negval"
lutyuv="y=negval:u=negval:v=negval"
</pre></div>
</li><li> Negate luminance:
<div class="example">
<pre class="example">lutyuv=y=negval
</pre></div>
</li><li> Remove chroma components, turning the video into a graytone image:
<div class="example">
<pre class="example">lutyuv="u=128:v=128"
</pre></div>
</li><li> Apply a luma burning effect:
<div class="example">
<pre class="example">lutyuv="y=2*val"
</pre></div>
</li><li> Remove green and blue components:
<div class="example">
<pre class="example">lutrgb="g=0:b=0"
</pre></div>
</li><li> Set a constant alpha channel value on input:
<div class="example">
<pre class="example">format=rgba,lutrgb=a="maxval-minval/2"
</pre></div>
</li><li> Correct luminance gamma by a factor of 0.5:
<div class="example">
<pre class="example">lutyuv=y=gammaval(0.5)
</pre></div>
</li><li> Discard least significant bits of luma:
<div class="example">
<pre class="example">lutyuv=y='bitand(val, 128+64+32)'
</pre></div>
</li></ul>
<a name="mergeplanes"></a>
<h3 class="section">37.71 mergeplanes<span class="pull-right"><a class="anchor hidden-xs" href="#mergeplanes" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mergeplanes" aria-hidden="true">TOC</a></span></h3>
<p>Merge color channel components from several video streams.
</p>
<p>The filter accepts up to 4 input streams, and merge selected input
planes to the output video.
</p>
<p>This filter accepts the following options:
</p><dl compact="compact">
<dt><samp>mapping</samp></dt>
<dd><p>Set input to output plane mapping. Default is <code>0</code>.
</p>
<p>The mappings is specified as a bitmap. It should be specified as a
hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. ’Aa’ describes the
mapping for the first plane of the output stream. ’A’ sets the number of
the input stream to use (from 0 to 3), and ’a’ the plane number of the
corresponding input to use (from 0 to 3). The rest of the mappings is
similar, ’Bb’ describes the mapping for the output stream second
plane, ’Cc’ describes the mapping for the output stream third plane and
’Dd’ describes the mapping for the output stream fourth plane.
</p>
</dd>
<dt><samp>format</samp></dt>
<dd><p>Set output pixel format. Default is <code>yuva444p</code>.
</p></dd>
</dl>
<a name="Examples-83"></a>
<h4 class="subsection">37.71.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-83" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-83" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Merge three gray video streams of same width and height into single video stream:
<div class="example">
<pre class="example">[a0][a1][a2]mergeplanes=0x001020:yuv444p
</pre></div>
</li><li> Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
<div class="example">
<pre class="example">[a0][a1]mergeplanes=0x00010210:yuva444p
</pre></div>
</li><li> Swap Y and A plane in yuva444p stream:
<div class="example">
<pre class="example">format=yuva444p,mergeplanes=0x03010200:yuva444p
</pre></div>
</li><li> Swap U and V plane in yuv420p stream:
<div class="example">
<pre class="example">format=yuv420p,mergeplanes=0x000201:yuv420p
</pre></div>
</li><li> Cast a rgb24 clip to yuv444p:
<div class="example">
<pre class="example">format=rgb24,mergeplanes=0x000102:yuv444p
</pre></div>
</li></ul>
<a name="mcdeint"></a>
<h3 class="section">37.72 mcdeint<span class="pull-right"><a class="anchor hidden-xs" href="#mcdeint" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mcdeint" aria-hidden="true">TOC</a></span></h3>
<p>Apply motion-compensation deinterlacing.
</p>
<p>It needs one field per frame as input and must thus be used together
with yadif=1/3 or equivalent.
</p>
<p>This filter accepts the following options:
</p><dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Set the deinterlacing mode.
</p>
<p>It accepts one of the following values:
</p><dl compact="compact">
<dt>‘<samp>fast</samp>’</dt>
<dt>‘<samp>medium</samp>’</dt>
<dt>‘<samp>slow</samp>’</dt>
<dd><p>use iterative motion estimation
</p></dd>
<dt>‘<samp>extra_slow</samp>’</dt>
<dd><p>like ‘<samp>slow</samp>’, but use multiple reference frames.
</p></dd>
</dl>
<p>Default value is ‘<samp>fast</samp>’.
</p>
</dd>
<dt><samp>parity</samp></dt>
<dd><p>Set the picture field parity assumed for the input video. It must be
one of the following values:
</p>
<dl compact="compact">
<dt>‘<samp>0, tff</samp>’</dt>
<dd><p>assume top field first
</p></dd>
<dt>‘<samp>1, bff</samp>’</dt>
<dd><p>assume bottom field first
</p></dd>
</dl>
<p>Default value is ‘<samp>bff</samp>’.
</p>
</dd>
<dt><samp>qp</samp></dt>
<dd><p>Set per-block quantization parameter (QP) used by the internal
encoder.
</p>
<p>Higher values should result in a smoother motion vector field but less
optimal individual vectors. Default value is 1.
</p></dd>
</dl>
<a name="mpdecimate"></a>
<h3 class="section">37.73 mpdecimate<span class="pull-right"><a class="anchor hidden-xs" href="#mpdecimate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mpdecimate" aria-hidden="true">TOC</a></span></h3>
<p>Drop frames that do not differ greatly from the previous frame in
order to reduce frame rate.
</p>
<p>The main use of this filter is for very-low-bitrate encoding
(e.g. streaming over dialup modem), but it could in theory be used for
fixing movies that were inverse-telecined incorrectly.
</p>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>max</samp></dt>
<dd><p>Set the maximum number of consecutive frames which can be dropped (if
positive), or the minimum interval between dropped frames (if
negative). If the value is 0, the frame is dropped unregarding the
number of previous sequentially dropped frames.
</p>
<p>Default value is 0.
</p>
</dd>
<dt><samp>hi</samp></dt>
<dt><samp>lo</samp></dt>
<dt><samp>frac</samp></dt>
<dd><p>Set the dropping threshold values.
</p>
<p>Values for <samp>hi</samp> and <samp>lo</samp> are for 8x8 pixel blocks and
represent actual pixel value differences, so a threshold of 64
corresponds to 1 unit of difference for each pixel, or the same spread
out differently over the block.
</p>
<p>A frame is a candidate for dropping if no 8x8 blocks differ by more
than a threshold of <samp>hi</samp>, and if no more than <samp>frac</samp> blocks (1
meaning the whole image) differ by more than a threshold of <samp>lo</samp>.
</p>
<p>Default value for <samp>hi</samp> is 64*12, default value for <samp>lo</samp> is
64*5, and default value for <samp>frac</samp> is 0.33.
</p></dd>
</dl>
<a name="negate"></a>
<h3 class="section">37.74 negate<span class="pull-right"><a class="anchor hidden-xs" href="#negate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-negate" aria-hidden="true">TOC</a></span></h3>
<p>Negate input video.
</p>
<p>It accepts an integer in input; if non-zero it negates the
alpha component (if available). The default value in input is 0.
</p>
<a name="noformat"></a>
<h3 class="section">37.75 noformat<span class="pull-right"><a class="anchor hidden-xs" href="#noformat" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-noformat" aria-hidden="true">TOC</a></span></h3>
<p>Force libavfilter not to use any of the specified pixel formats for the
input to the next filter.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>pix_fmts</samp></dt>
<dd><p>A ’|’-separated list of pixel format names, such as
apix_fmts=yuv420p|monow|rgb24".
</p>
</dd>
</dl>
<a name="Examples-84"></a>
<h4 class="subsection">37.75.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-84" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-84" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Force libavfilter to use a format different from <var>yuv420p</var> for the
input to the vflip filter:
<div class="example">
<pre class="example">noformat=pix_fmts=yuv420p,vflip
</pre></div>
</li><li> Convert the input video to any of the formats not contained in the list:
<div class="example">
<pre class="example">noformat=yuv420p|yuv444p|yuv410p
</pre></div>
</li></ul>
<a name="noise-1"></a>
<h3 class="section">37.76 noise<span class="pull-right"><a class="anchor hidden-xs" href="#noise-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-noise-1" aria-hidden="true">TOC</a></span></h3>
<p>Add noise on video input frame.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>all_seed</samp></dt>
<dt><samp>c0_seed</samp></dt>
<dt><samp>c1_seed</samp></dt>
<dt><samp>c2_seed</samp></dt>
<dt><samp>c3_seed</samp></dt>
<dd><p>Set noise seed for specific pixel component or all pixel components in case
of <var>all_seed</var>. Default value is <code>123457</code>.
</p>
</dd>
<dt><samp>all_strength, alls</samp></dt>
<dt><samp>c0_strength, c0s</samp></dt>
<dt><samp>c1_strength, c1s</samp></dt>
<dt><samp>c2_strength, c2s</samp></dt>
<dt><samp>c3_strength, c3s</samp></dt>
<dd><p>Set noise strength for specific pixel component or all pixel components in case
<var>all_strength</var>. Default value is <code>0</code>. Allowed range is [0, 100].
</p>
</dd>
<dt><samp>all_flags, allf</samp></dt>
<dt><samp>c0_flags, c0f</samp></dt>
<dt><samp>c1_flags, c1f</samp></dt>
<dt><samp>c2_flags, c2f</samp></dt>
<dt><samp>c3_flags, c3f</samp></dt>
<dd><p>Set pixel component flags or set flags for all components if <var>all_flags</var>.
Available values for component flags are:
</p><dl compact="compact">
<dt>‘<samp>a</samp>’</dt>
<dd><p>averaged temporal noise (smoother)
</p></dd>
<dt>‘<samp>p</samp>’</dt>
<dd><p>mix random noise with a (semi)regular pattern
</p></dd>
<dt>‘<samp>t</samp>’</dt>
<dd><p>temporal noise (noise pattern changes between frames)
</p></dd>
<dt>‘<samp>u</samp>’</dt>
<dd><p>uniform noise (gaussian otherwise)
</p></dd>
</dl>
</dd>
</dl>
<a name="Examples-85"></a>
<h4 class="subsection">37.76.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-85" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-85" aria-hidden="true">TOC</a></span></h4>
<p>Add temporal and uniform noise to input video:
</p><div class="example">
<pre class="example">noise=alls=20:allf=t+u
</pre></div>
<a name="null-1"></a>
<h3 class="section">37.77 null<span class="pull-right"><a class="anchor hidden-xs" href="#null-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-null-1" aria-hidden="true">TOC</a></span></h3>
<p>Pass the video source unchanged to the output.
</p>
<a name="ocv"></a>
<h3 class="section">37.78 ocv<span class="pull-right"><a class="anchor hidden-xs" href="#ocv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ocv" aria-hidden="true">TOC</a></span></h3>
<p>Apply a video transform using libopencv.
</p>
<p>To enable this filter, install the libopencv library and headers and
configure FFmpeg with <code>--enable-libopencv</code>.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>filter_name</samp></dt>
<dd><p>The name of the libopencv filter to apply.
</p>
</dd>
<dt><samp>filter_params</samp></dt>
<dd><p>The parameters to pass to the libopencv filter. If not specified, the default
values are assumed.
</p>
</dd>
</dl>
<p>Refer to the official libopencv documentation for more precise
information:
<a href="http://docs.opencv.org/master/modules/imgproc/doc/filtering.html">http://docs.opencv.org/master/modules/imgproc/doc/filtering.html</a>
</p>
<p>Several libopencv filters are supported; see the following subsections.
</p>
<a name="dilate"></a><a name="dilate-1"></a>
<h4 class="subsection">37.78.1 dilate<span class="pull-right"><a class="anchor hidden-xs" href="#dilate-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-dilate-1" aria-hidden="true">TOC</a></span></h4>
<p>Dilate an image by using a specific structuring element.
It corresponds to the libopencv function <code>cvDilate</code>.
</p>
<p>It accepts the parameters: <var>struct_el</var>|<var>nb_iterations</var>.
</p>
<p><var>struct_el</var> represents a structuring element, and has the syntax:
<var>cols</var>x<var>rows</var>+<var>anchor_x</var>x<var>anchor_y</var>/<var>shape</var>
</p>
<p><var>cols</var> and <var>rows</var> represent the number of columns and rows of
the structuring element, <var>anchor_x</var> and <var>anchor_y</var> the anchor
point, and <var>shape</var> the shape for the structuring element. <var>shape</var>
must be "rect", "cross", "ellipse", or "custom".
</p>
<p>If the value for <var>shape</var> is "custom", it must be followed by a
string of the form "=<var>filename</var>". The file with name
<var>filename</var> is assumed to represent a binary image, with each
printable character corresponding to a bright pixel. When a custom
<var>shape</var> is used, <var>cols</var> and <var>rows</var> are ignored, the number
or columns and rows of the read file are assumed instead.
</p>
<p>The default value for <var>struct_el</var> is "3x3+0x0/rect".
</p>
<p><var>nb_iterations</var> specifies the number of times the transform is
applied to the image, and defaults to 1.
</p>
<p>Some examples:
</p><div class="example">
<pre class="example"># Use the default values
ocv=dilate
# Dilate using a structuring element with a 5x5 cross, iterating two times
ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
# Read the shape from the file diamond.shape, iterating two times.
# The file diamond.shape may contain a pattern of characters like this
# *
# ***
# *****
# ***
# *
# The specified columns and rows are ignored
# but the anchor point coordinates are not
ocv=dilate:0x0+2x2/custom=diamond.shape|2
</pre></div>
<a name="erode"></a>
<h4 class="subsection">37.78.2 erode<span class="pull-right"><a class="anchor hidden-xs" href="#erode" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-erode" aria-hidden="true">TOC</a></span></h4>
<p>Erode an image by using a specific structuring element.
It corresponds to the libopencv function <code>cvErode</code>.
</p>
<p>It accepts the parameters: <var>struct_el</var>:<var>nb_iterations</var>,
with the same syntax and semantics as the <a href="#dilate">dilate</a> filter.
</p>
<a name="smooth"></a>
<h4 class="subsection">37.78.3 smooth<span class="pull-right"><a class="anchor hidden-xs" href="#smooth" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-smooth" aria-hidden="true">TOC</a></span></h4>
<p>Smooth the input video.
</p>
<p>The filter takes the following parameters:
<var>type</var>|<var>param1</var>|<var>param2</var>|<var>param3</var>|<var>param4</var>.
</p>
<p><var>type</var> is the type of smooth filter to apply, and must be one of
the following values: "blur", "blur_no_scale", "median", "gaussian",
or "bilateral". The default value is "gaussian".
</p>
<p>The meaning of <var>param1</var>, <var>param2</var>, <var>param3</var>, and <var>param4</var>
depend on the smooth type. <var>param1</var> and
<var>param2</var> accept integer positive values or 0. <var>param3</var> and
<var>param4</var> accept floating point values.
</p>
<p>The default value for <var>param1</var> is 3. The default value for the
other parameters is 0.
</p>
<p>These parameters correspond to the parameters assigned to the
libopencv function <code>cvSmooth</code>.
</p>
<a name="overlay"></a><a name="overlay-1"></a>
<h3 class="section">37.79 overlay<span class="pull-right"><a class="anchor hidden-xs" href="#overlay-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-overlay-1" aria-hidden="true">TOC</a></span></h3>
<p>Overlay one video on top of another.
</p>
<p>It takes two inputs and has one output. The first input is the "main"
video on which the second input is overlaid.
</p>
<p>It accepts the following parameters:
</p>
<p>A description of the accepted options follows.
</p>
<dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Set the expression for the x and y coordinates of the overlaid video
on the main video. Default value is "0" for both expressions. In case
the expression is invalid, it is set to a huge value (meaning that the
overlay will not be displayed within the output visible area).
</p>
</dd>
<dt><samp>eof_action</samp></dt>
<dd><p>The action to take when EOF is encountered on the secondary input; it accepts
one of the following values:
</p>
<dl compact="compact">
<dt><samp>repeat</samp></dt>
<dd><p>Repeat the last frame (the default).
</p></dd>
<dt><samp>endall</samp></dt>
<dd><p>End both streams.
</p></dd>
<dt><samp>pass</samp></dt>
<dd><p>Pass the main input through.
</p></dd>
</dl>
</dd>
<dt><samp>eval</samp></dt>
<dd><p>Set when the expressions for <samp>x</samp>, and <samp>y</samp> are evaluated.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>init</samp>’</dt>
<dd><p>only evaluate expressions once during the filter initialization or
when a command is processed
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>evaluate expressions for each incoming frame
</p></dd>
</dl>
<p>Default value is ‘<samp>frame</samp>’.
</p>
</dd>
<dt><samp>shortest</samp></dt>
<dd><p>If set to 1, force the output to terminate when the shortest input
terminates. Default value is 0.
</p>
</dd>
<dt><samp>format</samp></dt>
<dd><p>Set the format for the output video.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>yuv420</samp>’</dt>
<dd><p>force YUV420 output
</p>
</dd>
<dt>‘<samp>yuv422</samp>’</dt>
<dd><p>force YUV422 output
</p>
</dd>
<dt>‘<samp>yuv444</samp>’</dt>
<dd><p>force YUV444 output
</p>
</dd>
<dt>‘<samp>rgb</samp>’</dt>
<dd><p>force RGB output
</p></dd>
</dl>
<p>Default value is ‘<samp>yuv420</samp>’.
</p>
</dd>
<dt><samp>rgb <em>(deprecated)</em></samp></dt>
<dd><p>If set to 1, force the filter to accept inputs in the RGB
color space. Default value is 0. This option is deprecated, use
<samp>format</samp> instead.
</p>
</dd>
<dt><samp>repeatlast</samp></dt>
<dd><p>If set to 1, force the filter to draw the last overlay frame over the
main input until the end of the stream. A value of 0 disables this
behavior. Default value is 1.
</p></dd>
</dl>
<p>The <samp>x</samp>, and <samp>y</samp> expressions can contain the following
parameters.
</p>
<dl compact="compact">
<dt><samp>main_w, W</samp></dt>
<dt><samp>main_h, H</samp></dt>
<dd><p>The main input width and height.
</p>
</dd>
<dt><samp>overlay_w, w</samp></dt>
<dt><samp>overlay_h, h</samp></dt>
<dd><p>The overlay input width and height.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The computed values for <var>x</var> and <var>y</var>. They are evaluated for
each new frame.
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values of the output
format. For example for the pixel format "yuv422p" <var>hsub</var> is 2 and
<var>vsub</var> is 1.
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>the number of input frame, starting from 0
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>the position in the file of the input frame, NAN if unknown
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>The timestamp, expressed in seconds. It’s NAN if the input timestamp is unknown.
</p>
</dd>
</dl>
<p>Note that the <var>n</var>, <var>pos</var>, <var>t</var> variables are available only
when evaluation is done <em>per frame</em>, and will evaluate to NAN
when <samp>eval</samp> is set to ‘<samp>init</samp>’.
</p>
<p>Be aware that frames are taken from each input video in timestamp
order, hence, if their initial timestamps differ, it is a good idea
to pass the two inputs through a <var>setpts=PTS-STARTPTS</var> filter to
have them begin in the same zero timestamp, as the example for
the <var>movie</var> filter does.
</p>
<p>You can chain together more overlays but you should test the
efficiency of such approach.
</p>
<a name="Commands-5"></a>
<h4 class="subsection">37.79.1 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-5" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-5" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Modify the x and y of the overlay input.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
</dl>
<a name="Examples-86"></a>
<h4 class="subsection">37.79.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-86" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-86" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Draw the overlay at 10 pixels from the bottom right corner of the main
video:
<div class="example">
<pre class="example">overlay=main_w-overlay_w-10:main_h-overlay_h-10
</pre></div>
<p>Using named options the example above becomes:
</p><div class="example">
<pre class="example">overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
</pre></div>
</li><li> Insert a transparent PNG logo in the bottom left corner of the input,
using the <code>ffmpeg</code> tool with the <code>-filter_complex</code> option:
<div class="example">
<pre class="example">ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
</pre></div>
</li><li> Insert 2 different transparent PNG logos (second logo on bottom
right corner) using the <code>ffmpeg</code> tool:
<div class="example">
<pre class="example">ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
</pre></div>
</li><li> Add a transparent color layer on top of the main video; <code>WxH</code>
must specify the size of the main input to the overlay filter:
<div class="example">
<pre class="example">color=color=red@.3:size=WxH [over]; [in][over] overlay [out]
</pre></div>
</li><li> Play an original video and a filtered version (here with the deshake
filter) side by side using the <code>ffplay</code> tool:
<div class="example">
<pre class="example">ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
</pre></div>
<p>The above command is the same as:
</p><div class="example">
<pre class="example">ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
</pre></div>
</li><li> Make a sliding overlay appearing from the left to the right top part of the
screen starting since time 2:
<div class="example">
<pre class="example">overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
</pre></div>
</li><li> Compose output by putting two input videos side to side:
<div class="example">
<pre class="example">ffmpeg -i left.avi -i right.avi -filter_complex "
nullsrc=size=200x100 [background];
[0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
[1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
[background][left] overlay=shortest=1 [background+left];
[background+left][right] overlay=shortest=1:x=100 [left+right]
"
</pre></div>
</li><li> Mask 10-20 seconds of a video by applying the delogo filter to a section
<div class="example">
<pre class="example">ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
-vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
masked.avi
</pre></div>
</li><li> Chain several overlays in cascade:
<div class="example">
<pre class="example">nullsrc=s=200x200 [bg];
testsrc=s=100x100, split=4 [in0][in1][in2][in3];
[in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
[in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
[in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
[in3] null, [mid2] overlay=100:100 [out0]
</pre></div>
</li></ul>
<a name="owdenoise"></a>
<h3 class="section">37.80 owdenoise<span class="pull-right"><a class="anchor hidden-xs" href="#owdenoise" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-owdenoise" aria-hidden="true">TOC</a></span></h3>
<p>Apply Overcomplete Wavelet denoiser.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>depth</samp></dt>
<dd><p>Set depth.
</p>
<p>Larger depth values will denoise lower frequency components more, but
slow down filtering.
</p>
<p>Must be an int in the range 8-16, default is <code>8</code>.
</p>
</dd>
<dt><samp>luma_strength, ls</samp></dt>
<dd><p>Set luma strength.
</p>
<p>Must be a double value in the range 0-1000, default is <code>1.0</code>.
</p>
</dd>
<dt><samp>chroma_strength, cs</samp></dt>
<dd><p>Set chroma strength.
</p>
<p>Must be a double value in the range 0-1000, default is <code>1.0</code>.
</p></dd>
</dl>
<a name="pad"></a><a name="pad-1"></a>
<h3 class="section">37.81 pad<span class="pull-right"><a class="anchor hidden-xs" href="#pad-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pad-1" aria-hidden="true">TOC</a></span></h3>
<p>Add paddings to the input image, and place the original input at the
provided <var>x</var>, <var>y</var> coordinates.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>width, w</samp></dt>
<dt><samp>height, h</samp></dt>
<dd><p>Specify an expression for the size of the output image with the
paddings added. If the value for <var>width</var> or <var>height</var> is 0, the
corresponding input size is used for the output.
</p>
<p>The <var>width</var> expression can reference the value set by the
<var>height</var> expression, and vice versa.
</p>
<p>The default value of <var>width</var> and <var>height</var> is 0.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Specify the offsets to place the input image at within the padded area,
with respect to the top/left border of the output image.
</p>
<p>The <var>x</var> expression can reference the value set by the <var>y</var>
expression, and vice versa.
</p>
<p>The default value of <var>x</var> and <var>y</var> is 0.
</p>
</dd>
<dt><samp>color</samp></dt>
<dd><p>Specify the color of the padded area. For the syntax of this option,
check the "Color" section in the ffmpeg-utils manual.
</p>
<p>The default value of <var>color</var> is "black".
</p></dd>
</dl>
<p>The value for the <var>width</var>, <var>height</var>, <var>x</var>, and <var>y</var>
options are expressions containing the following constants:
</p>
<dl compact="compact">
<dt><samp>in_w</samp></dt>
<dt><samp>in_h</samp></dt>
<dd><p>The input video width and height.
</p>
</dd>
<dt><samp>iw</samp></dt>
<dt><samp>ih</samp></dt>
<dd><p>These are the same as <var>in_w</var> and <var>in_h</var>.
</p>
</dd>
<dt><samp>out_w</samp></dt>
<dt><samp>out_h</samp></dt>
<dd><p>The output width and height (the size of the padded area), as
specified by the <var>width</var> and <var>height</var> expressions.
</p>
</dd>
<dt><samp>ow</samp></dt>
<dt><samp>oh</samp></dt>
<dd><p>These are the same as <var>out_w</var> and <var>out_h</var>.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>The x and y offsets as specified by the <var>x</var> and <var>y</var>
expressions, or NAN if not yet specified.
</p>
</dd>
<dt><samp>a</samp></dt>
<dd><p>same as <var>iw</var> / <var>ih</var>
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>input sample aspect ratio
</p>
</dd>
<dt><samp>dar</samp></dt>
<dd><p>input display aspect ratio, it is the same as (<var>iw</var> / <var>ih</var>) * <var>sar</var>
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>The horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p></dd>
</dl>
<a name="Examples-87"></a>
<h4 class="subsection">37.81.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-87" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-87" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Add paddings with the color "violet" to the input video. The output video
size is 640x480, and the top-left corner of the input video is placed at
column 0, row 40
<div class="example">
<pre class="example">pad=640:480:0:40:violet
</pre></div>
<p>The example above is equivalent to the following command:
</p><div class="example">
<pre class="example">pad=width=640:height=480:x=0:y=40:color=violet
</pre></div>
</li><li> Pad the input to get an output with dimensions increased by 3/2,
and put the input video at the center of the padded area:
<div class="example">
<pre class="example">pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
</pre></div>
</li><li> Pad the input to get a squared output with size equal to the maximum
value between the input width and height, and put the input video at
the center of the padded area:
<div class="example">
<pre class="example">pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
</pre></div>
</li><li> Pad the input to get a final w/h ratio of 16:9:
<div class="example">
<pre class="example">pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
</pre></div>
</li><li> In case of anamorphic video, in order to set the output display aspect
correctly, it is necessary to use <var>sar</var> in the expression,
according to the relation:
<div class="example">
<pre class="example">(ih * X / ih) * sar = output_dar
X = output_dar / sar
</pre></div>
<p>Thus the previous example needs to be modified to:
</p><div class="example">
<pre class="example">pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
</pre></div>
</li><li> Double the output size and put the input video in the bottom-right
corner of the output padded area:
<div class="example">
<pre class="example">pad="2*iw:2*ih:ow-iw:oh-ih"
</pre></div>
</li></ul>
<a name="palettegen"></a><a name="palettegen-1"></a>
<h3 class="section">37.82 palettegen<span class="pull-right"><a class="anchor hidden-xs" href="#palettegen-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-palettegen-1" aria-hidden="true">TOC</a></span></h3>
<p>Generate one palette for a whole video stream.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>max_colors</samp></dt>
<dd><p>Set the maximum number of colors to quantize in the palette.
Note: the palette will still contain 256 colors; the unused palette entries
will be black.
</p>
</dd>
<dt><samp>reserve_transparent</samp></dt>
<dd><p>Create a palette of 255 colors maximum and reserve the last one for
transparency. Reserving the transparency color is useful for GIF optimization.
If not set, the maximum of colors in the palette will be 256. You probably want
to disable this option for a standalone image.
Set by default.
</p>
</dd>
<dt><samp>stats_mode</samp></dt>
<dd><p>Set statistics mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>full</samp>’</dt>
<dd><p>Compute full frame histograms.
</p></dd>
<dt>‘<samp>diff</samp>’</dt>
<dd><p>Compute histograms only for the part that differs from previous frame. This
might be relevant to give more importance to the moving part of your input if
the background is static.
</p></dd>
</dl>
<p>Default value is <var>full</var>.
</p></dd>
</dl>
<p>The filter also exports the frame metadata <code>lavfi.color_quant_ratio</code>
(<code>nb_color_in / nb_color_out</code>) which you can use to evaluate the degree of
color quantization of the palette. This information is also visible at
<var>info</var> logging level.
</p>
<a name="Examples-88"></a>
<h4 class="subsection">37.82.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-88" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-88" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Generate a representative palette of a given video using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i input.mkv -vf palettegen palette.png
</pre></div>
</li></ul>
<a name="paletteuse"></a>
<h3 class="section">37.83 paletteuse<span class="pull-right"><a class="anchor hidden-xs" href="#paletteuse" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-paletteuse" aria-hidden="true">TOC</a></span></h3>
<p>Use a palette to downsample an input video stream.
</p>
<p>The filter takes two inputs: one video stream and a palette. The palette must
be a 256 pixels image.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>dither</samp></dt>
<dd><p>Select dithering mode. Available algorithms are:
</p><dl compact="compact">
<dt>‘<samp>bayer</samp>’</dt>
<dd><p>Ordered 8x8 bayer dithering (deterministic)
</p></dd>
<dt>‘<samp>heckbert</samp>’</dt>
<dd><p>Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
Note: this dithering is sometimes considered "wrong" and is included as a
reference.
</p></dd>
<dt>‘<samp>floyd_steinberg</samp>’</dt>
<dd><p>Floyd and Steingberg dithering (error diffusion)
</p></dd>
<dt>‘<samp>sierra2</samp>’</dt>
<dd><p>Frankie Sierra dithering v2 (error diffusion)
</p></dd>
<dt>‘<samp>sierra2_4a</samp>’</dt>
<dd><p>Frankie Sierra dithering v2 "Lite" (error diffusion)
</p></dd>
</dl>
<p>Default is <var>sierra2_4a</var>.
</p>
</dd>
<dt><samp>bayer_scale</samp></dt>
<dd><p>When <var>bayer</var> dithering is selected, this option defines the scale of the
pattern (how much the crosshatch pattern is visible). A low value means more
visible pattern for less banding, and higher value means less visible pattern
at the cost of more banding.
</p>
<p>The option must be an integer value in the range [0,5]. Default is <var>2</var>.
</p>
</dd>
<dt><samp>diff_mode</samp></dt>
<dd><p>If set, define the zone to process
</p>
<dl compact="compact">
<dt>‘<samp>rectangle</samp>’</dt>
<dd><p>Only the changing rectangle will be reprocessed. This is similar to GIF
cropping/offsetting compression mechanism. This option can be useful for speed
if only a part of the image is changing, and has use cases such as limiting the
scope of the error diffusal <samp>dither</samp> to the rectangle that bounds the
moving scene (it leads to more deterministic output if the scene doesn’t change
much, and as a result less moving noise and better GIF compression).
</p></dd>
</dl>
<p>Default is <var>none</var>.
</p></dd>
</dl>
<a name="Examples-89"></a>
<h4 class="subsection">37.83.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-89" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-89" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use a palette (generated for example with <a href="#palettegen">palettegen</a>) to encode a GIF
using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
</pre></div>
</li></ul>
<a name="perspective"></a>
<h3 class="section">37.84 perspective<span class="pull-right"><a class="anchor hidden-xs" href="#perspective" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-perspective" aria-hidden="true">TOC</a></span></h3>
<p>Correct perspective of video not recorded perpendicular to the screen.
</p>
<p>A description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>x0</samp></dt>
<dt><samp>y0</samp></dt>
<dt><samp>x1</samp></dt>
<dt><samp>y1</samp></dt>
<dt><samp>x2</samp></dt>
<dt><samp>y2</samp></dt>
<dt><samp>x3</samp></dt>
<dt><samp>y3</samp></dt>
<dd><p>Set coordinates expression for top left, top right, bottom left and bottom right corners.
Default values are <code>0:0:W:0:0:H:W:H</code> with which perspective will remain unchanged.
If the <code>sense</code> option is set to <code>source</code>, then the specified points will be sent
to the corners of the destination. If the <code>sense</code> option is set to <code>destination</code>,
then the corners of the source will be sent to the specified coordinates.
</p>
<p>The expressions can use the following variables:
</p>
<dl compact="compact">
<dt><samp>W</samp></dt>
<dt><samp>H</samp></dt>
<dd><p>the width and height of video frame.
</p></dd>
</dl>
</dd>
<dt><samp>interpolation</samp></dt>
<dd><p>Set interpolation for perspective correction.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>linear</samp>’</dt>
<dt>‘<samp>cubic</samp>’</dt>
</dl>
<p>Default value is ‘<samp>linear</samp>’.
</p>
</dd>
<dt><samp>sense</samp></dt>
<dd><p>Set interpretation of coordinate options.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>0, source</samp>’</dt>
<dd>
<p>Send point in the source specified by the given coordinates to
the corners of the destination.
</p>
</dd>
<dt>‘<samp>1, destination</samp>’</dt>
<dd>
<p>Send the corners of the source to the point in the destination specified
by the given coordinates.
</p>
<p>Default value is ‘<samp>source</samp>’.
</p></dd>
</dl>
</dd>
</dl>
<a name="phase"></a>
<h3 class="section">37.85 phase<span class="pull-right"><a class="anchor hidden-xs" href="#phase" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-phase" aria-hidden="true">TOC</a></span></h3>
<p>Delay interlaced video by one field time so that the field order changes.
</p>
<p>The intended use is to fix PAL movies that have been captured with the
opposite field order to the film-to-video transfer.
</p>
<p>A description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Set phase mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>t</samp>’</dt>
<dd><p>Capture field order top-first, transfer bottom-first.
Filter will delay the bottom field.
</p>
</dd>
<dt>‘<samp>b</samp>’</dt>
<dd><p>Capture field order bottom-first, transfer top-first.
Filter will delay the top field.
</p>
</dd>
<dt>‘<samp>p</samp>’</dt>
<dd><p>Capture and transfer with the same field order. This mode only exists
for the documentation of the other options to refer to, but if you
actually select it, the filter will faithfully do nothing.
</p>
</dd>
<dt>‘<samp>a</samp>’</dt>
<dd><p>Capture field order determined automatically by field flags, transfer
opposite.
Filter selects among ‘<samp>t</samp>’ and ‘<samp>b</samp>’ modes on a frame by frame
basis using field flags. If no field information is available,
then this works just like ‘<samp>u</samp>’.
</p>
</dd>
<dt>‘<samp>u</samp>’</dt>
<dd><p>Capture unknown or varying, transfer opposite.
Filter selects among ‘<samp>t</samp>’ and ‘<samp>b</samp>’ on a frame by frame basis by
analyzing the images and selecting the alternative that produces best
match between the fields.
</p>
</dd>
<dt>‘<samp>T</samp>’</dt>
<dd><p>Capture top-first, transfer unknown or varying.
Filter selects among ‘<samp>t</samp>’ and ‘<samp>p</samp>’ using image analysis.
</p>
</dd>
<dt>‘<samp>B</samp>’</dt>
<dd><p>Capture bottom-first, transfer unknown or varying.
Filter selects among ‘<samp>b</samp>’ and ‘<samp>p</samp>’ using image analysis.
</p>
</dd>
<dt>‘<samp>A</samp>’</dt>
<dd><p>Capture determined by field flags, transfer unknown or varying.
Filter selects among ‘<samp>t</samp>’, ‘<samp>b</samp>’ and ‘<samp>p</samp>’ using field flags and
image analysis. If no field information is available, then this works just
like ‘<samp>U</samp>’. This is the default mode.
</p>
</dd>
<dt>‘<samp>U</samp>’</dt>
<dd><p>Both capture and transfer unknown or varying.
Filter selects among ‘<samp>t</samp>’, ‘<samp>b</samp>’ and ‘<samp>p</samp>’ using image analysis only.
</p></dd>
</dl>
</dd>
</dl>
<a name="pixdesctest"></a>
<h3 class="section">37.86 pixdesctest<span class="pull-right"><a class="anchor hidden-xs" href="#pixdesctest" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pixdesctest" aria-hidden="true">TOC</a></span></h3>
<p>Pixel format descriptor test filter, mainly useful for internal
testing. The output video should be equal to the input video.
</p>
<p>For example:
</p><div class="example">
<pre class="example">format=monow, pixdesctest
</pre></div>
<p>can be used to test the monowhite pixel format descriptor definition.
</p>
<a name="pp"></a>
<h3 class="section">37.87 pp<span class="pull-right"><a class="anchor hidden-xs" href="#pp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pp" aria-hidden="true">TOC</a></span></h3>
<p>Enable the specified chain of postprocessing subfilters using libpostproc. This
library should be automatically selected with a GPL build (<code>--enable-gpl</code>).
Subfilters must be separated by ’/’ and can be disabled by prepending a ’-’.
Each subfilter and some options have a short and a long name that can be used
interchangeably, i.e. dr/dering are the same.
</p>
<p>The filters accept the following options:
</p>
<dl compact="compact">
<dt><samp>subfilters</samp></dt>
<dd><p>Set postprocessing subfilters string.
</p></dd>
</dl>
<p>All subfilters share common options to determine their scope:
</p>
<dl compact="compact">
<dt><samp>a/autoq</samp></dt>
<dd><p>Honor the quality commands for this subfilter.
</p>
</dd>
<dt><samp>c/chrom</samp></dt>
<dd><p>Do chrominance filtering, too (default).
</p>
</dd>
<dt><samp>y/nochrom</samp></dt>
<dd><p>Do luminance filtering only (no chrominance).
</p>
</dd>
<dt><samp>n/noluma</samp></dt>
<dd><p>Do chrominance filtering only (no luminance).
</p></dd>
</dl>
<p>These options can be appended after the subfilter name, separated by a ’|’.
</p>
<p>Available subfilters are:
</p>
<dl compact="compact">
<dt><samp>hb/hdeblock[|difference[|flatness]]</samp></dt>
<dd><p>Horizontal deblocking filter
</p><dl compact="compact">
<dt><samp>difference</samp></dt>
<dd><p>Difference factor where higher values mean more deblocking (default: <code>32</code>).
</p></dd>
<dt><samp>flatness</samp></dt>
<dd><p>Flatness threshold where lower values mean more deblocking (default: <code>39</code>).
</p></dd>
</dl>
</dd>
<dt><samp>vb/vdeblock[|difference[|flatness]]</samp></dt>
<dd><p>Vertical deblocking filter
</p><dl compact="compact">
<dt><samp>difference</samp></dt>
<dd><p>Difference factor where higher values mean more deblocking (default: <code>32</code>).
</p></dd>
<dt><samp>flatness</samp></dt>
<dd><p>Flatness threshold where lower values mean more deblocking (default: <code>39</code>).
</p></dd>
</dl>
</dd>
<dt><samp>ha/hadeblock[|difference[|flatness]]</samp></dt>
<dd><p>Accurate horizontal deblocking filter
</p><dl compact="compact">
<dt><samp>difference</samp></dt>
<dd><p>Difference factor where higher values mean more deblocking (default: <code>32</code>).
</p></dd>
<dt><samp>flatness</samp></dt>
<dd><p>Flatness threshold where lower values mean more deblocking (default: <code>39</code>).
</p></dd>
</dl>
</dd>
<dt><samp>va/vadeblock[|difference[|flatness]]</samp></dt>
<dd><p>Accurate vertical deblocking filter
</p><dl compact="compact">
<dt><samp>difference</samp></dt>
<dd><p>Difference factor where higher values mean more deblocking (default: <code>32</code>).
</p></dd>
<dt><samp>flatness</samp></dt>
<dd><p>Flatness threshold where lower values mean more deblocking (default: <code>39</code>).
</p></dd>
</dl>
</dd>
</dl>
<p>The horizontal and vertical deblocking filters share the difference and
flatness values so you cannot set different horizontal and vertical
thresholds.
</p>
<dl compact="compact">
<dt><samp>h1/x1hdeblock</samp></dt>
<dd><p>Experimental horizontal deblocking filter
</p>
</dd>
<dt><samp>v1/x1vdeblock</samp></dt>
<dd><p>Experimental vertical deblocking filter
</p>
</dd>
<dt><samp>dr/dering</samp></dt>
<dd><p>Deringing filter
</p>
</dd>
<dt><samp>tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer</samp></dt>
<dd><dl compact="compact">
<dt><samp>threshold1</samp></dt>
<dd><p>larger -> stronger filtering
</p></dd>
<dt><samp>threshold2</samp></dt>
<dd><p>larger -> stronger filtering
</p></dd>
<dt><samp>threshold3</samp></dt>
<dd><p>larger -> stronger filtering
</p></dd>
</dl>
</dd>
<dt><samp>al/autolevels[:f/fullyrange], automatic brightness / contrast correction</samp></dt>
<dd><dl compact="compact">
<dt><samp>f/fullyrange</samp></dt>
<dd><p>Stretch luminance to <code>0-255</code>.
</p></dd>
</dl>
</dd>
<dt><samp>lb/linblenddeint</samp></dt>
<dd><p>Linear blend deinterlacing filter that deinterlaces the given block by
filtering all lines with a <code>(1 2 1)</code> filter.
</p>
</dd>
<dt><samp>li/linipoldeint</samp></dt>
<dd><p>Linear interpolating deinterlacing filter that deinterlaces the given block by
linearly interpolating every second line.
</p>
</dd>
<dt><samp>ci/cubicipoldeint</samp></dt>
<dd><p>Cubic interpolating deinterlacing filter deinterlaces the given block by
cubically interpolating every second line.
</p>
</dd>
<dt><samp>md/mediandeint</samp></dt>
<dd><p>Median deinterlacing filter that deinterlaces the given block by applying a
median filter to every second line.
</p>
</dd>
<dt><samp>fd/ffmpegdeint</samp></dt>
<dd><p>FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
second line with a <code>(-1 4 2 4 -1)</code> filter.
</p>
</dd>
<dt><samp>l5/lowpass5</samp></dt>
<dd><p>Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
block by filtering all lines with a <code>(-1 2 6 2 -1)</code> filter.
</p>
</dd>
<dt><samp>fq/forceQuant[|quantizer]</samp></dt>
<dd><p>Overrides the quantizer table from the input with the constant quantizer you
specify.
</p><dl compact="compact">
<dt><samp>quantizer</samp></dt>
<dd><p>Quantizer to use
</p></dd>
</dl>
</dd>
<dt><samp>de/default</samp></dt>
<dd><p>Default pp filter combination (<code>hb|a,vb|a,dr|a</code>)
</p>
</dd>
<dt><samp>fa/fast</samp></dt>
<dd><p>Fast pp filter combination (<code>h1|a,v1|a,dr|a</code>)
</p>
</dd>
<dt><samp>ac</samp></dt>
<dd><p>High quality pp filter combination (<code>ha|a|128|7,va|a,dr|a</code>)
</p></dd>
</dl>
<a name="Examples-90"></a>
<h4 class="subsection">37.87.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-90" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-90" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply horizontal and vertical deblocking, deringing and automatic
brightness/contrast:
<div class="example">
<pre class="example">pp=hb/vb/dr/al
</pre></div>
</li><li> Apply default filters without brightness/contrast correction:
<div class="example">
<pre class="example">pp=de/-al
</pre></div>
</li><li> Apply default filters and temporal denoiser:
<div class="example">
<pre class="example">pp=default/tmpnoise|1|2|3
</pre></div>
</li><li> Apply deblocking on luminance only, and switch vertical deblocking on or off
automatically depending on available CPU time:
<div class="example">
<pre class="example">pp=hb|y/vb|a
</pre></div>
</li></ul>
<a name="pp7"></a>
<h3 class="section">37.88 pp7<span class="pull-right"><a class="anchor hidden-xs" href="#pp7" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pp7" aria-hidden="true">TOC</a></span></h3>
<p>Apply Postprocessing filter 7. It is variant of the <a href="#spp">spp</a> filter,
similar to spp = 6 with 7 point DCT, where only the center sample is
used after IDCT.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>qp</samp></dt>
<dd><p>Force a constant quantization parameter. It accepts an integer in range
0 to 63. If not set, the filter will use the QP from the video stream
(if available).
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set thresholding mode. Available modes are:
</p>
<dl compact="compact">
<dt>‘<samp>hard</samp>’</dt>
<dd><p>Set hard thresholding.
</p></dd>
<dt>‘<samp>soft</samp>’</dt>
<dd><p>Set soft thresholding (better de-ringing effect, but likely blurrier).
</p></dd>
<dt>‘<samp>medium</samp>’</dt>
<dd><p>Set medium thresholding (good results, default).
</p></dd>
</dl>
</dd>
</dl>
<a name="psnr"></a>
<h3 class="section">37.89 psnr<span class="pull-right"><a class="anchor hidden-xs" href="#psnr" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-psnr" aria-hidden="true">TOC</a></span></h3>
<p>Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
Ratio) between two input videos.
</p>
<p>This filter takes in input two input videos, the first input is
considered the "main" source and is passed unchanged to the
output. The second input is used as a "reference" video for computing
the PSNR.
</p>
<p>Both video inputs must have the same resolution and pixel format for
this filter to work correctly. Also it assumes that both inputs
have the same number of frames, which are compared one by one.
</p>
<p>The obtained average PSNR is printed through the logging system.
</p>
<p>The filter stores the accumulated MSE (mean squared error) of each
frame, and at the end of the processing it is averaged across all frames
equally, and the following formula is applied to obtain the PSNR:
</p>
<div class="example">
<pre class="example">PSNR = 10*log10(MAX^2/MSE)
</pre></div>
<p>Where MAX is the average of the maximum values of each component of the
image.
</p>
<p>The description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>stats_file, f</samp></dt>
<dd><p>If specified the filter will use the named file to save the PSNR of
each individual frame.
</p></dd>
</dl>
<p>The file printed if <var>stats_file</var> is selected, contains a sequence of
key/value pairs of the form <var>key</var>:<var>value</var> for each compared
couple of frames.
</p>
<p>A description of each shown parameter follows:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>sequential number of the input frame, starting from 1
</p>
</dd>
<dt><samp>mse_avg</samp></dt>
<dd><p>Mean Square Error pixel-by-pixel average difference of the compared
frames, averaged over all the image components.
</p>
</dd>
<dt><samp>mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a</samp></dt>
<dd><p>Mean Square Error pixel-by-pixel average difference of the compared
frames for the component specified by the suffix.
</p>
</dd>
<dt><samp>psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a</samp></dt>
<dd><p>Peak Signal to Noise ratio of the compared frames for the component
specified by the suffix.
</p></dd>
</dl>
<p>For example:
</p><div class="example">
<pre class="example">movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
[main][ref] psnr="stats_file=stats.log" [out]
</pre></div>
<p>On this example the input file being processed is compared with the
reference file <samp>ref_movie.mpg</samp>. The PSNR of each individual frame
is stored in <samp>stats.log</samp>.
</p>
<a name="pullup"></a><a name="pullup-1"></a>
<h3 class="section">37.90 pullup<span class="pull-right"><a class="anchor hidden-xs" href="#pullup-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-pullup-1" aria-hidden="true">TOC</a></span></h3>
<p>Pulldown reversal (inverse telecine) filter, capable of handling mixed
hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
content.
</p>
<p>The pullup filter is designed to take advantage of future context in making
its decisions. This filter is stateless in the sense that it does not lock
onto a pattern to follow, but it instead looks forward to the following
fields in order to identify matches and rebuild progressive frames.
</p>
<p>To produce content with an even framerate, insert the fps filter after
pullup, use <code>fps=24000/1001</code> if the input frame rate is 29.97fps,
<code>fps=24</code> for 30fps and the (rare) telecined 25fps input.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>jl</samp></dt>
<dt><samp>jr</samp></dt>
<dt><samp>jt</samp></dt>
<dt><samp>jb</samp></dt>
<dd><p>These options set the amount of "junk" to ignore at the left, right, top, and
bottom of the image, respectively. Left and right are in units of 8 pixels,
while top and bottom are in units of 2 lines.
The default is 8 pixels on each side.
</p>
</dd>
<dt><samp>sb</samp></dt>
<dd><p>Set the strict breaks. Setting this option to 1 will reduce the chances of
filter generating an occasional mismatched frame, but it may also cause an
excessive number of frames to be dropped during high motion sequences.
Conversely, setting it to -1 will make filter match fields more easily.
This may help processing of video where there is slight blurring between
the fields, but may also cause there to be interlaced frames in the output.
Default value is <code>0</code>.
</p>
</dd>
<dt><samp>mp</samp></dt>
<dd><p>Set the metric plane to use. It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>l</samp>’</dt>
<dd><p>Use luma plane.
</p>
</dd>
<dt>‘<samp>u</samp>’</dt>
<dd><p>Use chroma blue plane.
</p>
</dd>
<dt>‘<samp>v</samp>’</dt>
<dd><p>Use chroma red plane.
</p></dd>
</dl>
<p>This option may be set to use chroma plane instead of the default luma plane
for doing filter’s computations. This may improve accuracy on very clean
source material, but more likely will decrease accuracy, especially if there
is chroma noise (rainbow effect) or any grayscale video.
The main purpose of setting <samp>mp</samp> to a chroma plane is to reduce CPU
load and make pullup usable in realtime on slow machines.
</p></dd>
</dl>
<p>For best results (without duplicated frames in the output file) it is
necessary to change the output frame rate. For example, to inverse
telecine NTSC input:
</p><div class="example">
<pre class="example">ffmpeg -i input -vf pullup -r 24000/1001 ...
</pre></div>
<a name="qp"></a>
<h3 class="section">37.91 qp<span class="pull-right"><a class="anchor hidden-xs" href="#qp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-qp" aria-hidden="true">TOC</a></span></h3>
<p>Change video quantization parameters (QP).
</p>
<p>The filter accepts the following option:
</p>
<dl compact="compact">
<dt><samp>qp</samp></dt>
<dd><p>Set expression for quantization parameter.
</p></dd>
</dl>
<p>The expression is evaluated through the eval API and can contain, among others,
the following constants:
</p>
<dl compact="compact">
<dt><var>known</var></dt>
<dd><p>1 if index is not 129, 0 otherwise.
</p>
</dd>
<dt><var>qp</var></dt>
<dd><p>Sequentional index starting from -129 to 128.
</p></dd>
</dl>
<a name="Examples-91"></a>
<h4 class="subsection">37.91.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-91" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-91" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Some equation like:
<div class="example">
<pre class="example">qp=2+2*sin(PI*qp)
</pre></div>
</li></ul>
<a name="random"></a>
<h3 class="section">37.92 random<span class="pull-right"><a class="anchor hidden-xs" href="#random" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-random" aria-hidden="true">TOC</a></span></h3>
<p>Flush video frames from internal cache of frames into a random order.
No frame is discarded.
Inspired by <a href="#frei0r">frei0r</a> nervous filter.
</p>
<dl compact="compact">
<dt><samp>frames</samp></dt>
<dd><p>Set size in number of frames of internal cache, in range from <code>2</code> to
<code>512</code>. Default is <code>30</code>.
</p>
</dd>
<dt><samp>seed</samp></dt>
<dd><p>Set seed for random number generator, must be an integer included between
<code>0</code> and <code>UINT32_MAX</code>. If not specified, or if explicitly set to
less than <code>0</code>, the filter will try to use a good random seed on a
best effort basis.
</p></dd>
</dl>
<a name="removegrain"></a>
<h3 class="section">37.93 removegrain<span class="pull-right"><a class="anchor hidden-xs" href="#removegrain" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-removegrain" aria-hidden="true">TOC</a></span></h3>
<p>The removegrain filter is a spatial denoiser for progressive video.
</p>
<dl compact="compact">
<dt><samp>m0</samp></dt>
<dd><p>Set mode for the first plane.
</p>
</dd>
<dt><samp>m1</samp></dt>
<dd><p>Set mode for the second plane.
</p>
</dd>
<dt><samp>m2</samp></dt>
<dd><p>Set mode for the third plane.
</p>
</dd>
<dt><samp>m3</samp></dt>
<dd><p>Set mode for the fourth plane.
</p></dd>
</dl>
<p>Range of mode is from 0 to 24. Description of each mode follows:
</p>
<dl compact="compact">
<dt><var>0</var></dt>
<dd><p>Leave input plane unchanged. Default.
</p>
</dd>
<dt><var>1</var></dt>
<dd><p>Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
</p>
</dd>
<dt><var>2</var></dt>
<dd><p>Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
</p>
</dd>
<dt><var>3</var></dt>
<dd><p>Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
</p>
</dd>
<dt><var>4</var></dt>
<dd><p>Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
This is equivalent to a median filter.
</p>
</dd>
<dt><var>5</var></dt>
<dd><p>Line-sensitive clipping giving the minimal change.
</p>
</dd>
<dt><var>6</var></dt>
<dd><p>Line-sensitive clipping, intermediate.
</p>
</dd>
<dt><var>7</var></dt>
<dd><p>Line-sensitive clipping, intermediate.
</p>
</dd>
<dt><var>8</var></dt>
<dd><p>Line-sensitive clipping, intermediate.
</p>
</dd>
<dt><var>9</var></dt>
<dd><p>Line-sensitive clipping on a line where the neighbours pixels are the closest.
</p>
</dd>
<dt><var>10</var></dt>
<dd><p>Replaces the target pixel with the closest neighbour.
</p>
</dd>
<dt><var>11</var></dt>
<dd><p>[1 2 1] horizontal and vertical kernel blur.
</p>
</dd>
<dt><var>12</var></dt>
<dd><p>Same as mode 11.
</p>
</dd>
<dt><var>13</var></dt>
<dd><p>Bob mode, interpolates top field from the line where the neighbours
pixels are the closest.
</p>
</dd>
<dt><var>14</var></dt>
<dd><p>Bob mode, interpolates bottom field from the line where the neighbours
pixels are the closest.
</p>
</dd>
<dt><var>15</var></dt>
<dd><p>Bob mode, interpolates top field. Same as 13 but with a more complicated
interpolation formula.
</p>
</dd>
<dt><var>16</var></dt>
<dd><p>Bob mode, interpolates bottom field. Same as 14 but with a more complicated
interpolation formula.
</p>
</dd>
<dt><var>17</var></dt>
<dd><p>Clips the pixel with the minimum and maximum of respectively the maximum and
minimum of each pair of opposite neighbour pixels.
</p>
</dd>
<dt><var>18</var></dt>
<dd><p>Line-sensitive clipping using opposite neighbours whose greatest distance from
the current pixel is minimal.
</p>
</dd>
<dt><var>19</var></dt>
<dd><p>Replaces the pixel with the average of its 8 neighbours.
</p>
</dd>
<dt><var>20</var></dt>
<dd><p>Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
</p>
</dd>
<dt><var>21</var></dt>
<dd><p>Clips pixels using the averages of opposite neighbour.
</p>
</dd>
<dt><var>22</var></dt>
<dd><p>Same as mode 21 but simpler and faster.
</p>
</dd>
<dt><var>23</var></dt>
<dd><p>Small edge and halo removal, but reputed useless.
</p>
</dd>
<dt><var>24</var></dt>
<dd><p>Similar as 23.
</p></dd>
</dl>
<a name="removelogo"></a>
<h3 class="section">37.94 removelogo<span class="pull-right"><a class="anchor hidden-xs" href="#removelogo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-removelogo" aria-hidden="true">TOC</a></span></h3>
<p>Suppress a TV station logo, using an image file to determine which
pixels comprise the logo. It works by filling in the pixels that
comprise the logo with neighboring pixels.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>filename, f</samp></dt>
<dd><p>Set the filter bitmap file, which can be any image format supported by
libavformat. The width and height of the image file must match those of the
video stream being processed.
</p></dd>
</dl>
<p>Pixels in the provided bitmap image with a value of zero are not
considered part of the logo, non-zero pixels are considered part of
the logo. If you use white (255) for the logo and black (0) for the
rest, you will be safe. For making the filter bitmap, it is
recommended to take a screen capture of a black frame with the logo
visible, and then using a threshold filter followed by the erode
filter once or twice.
</p>
<p>If needed, little splotches can be fixed manually. Remember that if
logo pixels are not covered, the filter quality will be much
reduced. Marking too many pixels as part of the logo does not hurt as
much, but it will increase the amount of blurring needed to cover over
the image and will destroy more information than necessary, and extra
pixels will slow things down on a large logo.
</p>
<a name="repeatfields"></a>
<h3 class="section">37.95 repeatfields<span class="pull-right"><a class="anchor hidden-xs" href="#repeatfields" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-repeatfields" aria-hidden="true">TOC</a></span></h3>
<p>This filter uses the repeat_field flag from the Video ES headers and hard repeats
fields based on its value.
</p>
<a name="reverse_002c-areverse"></a>
<h3 class="section">37.96 reverse, areverse<span class="pull-right"><a class="anchor hidden-xs" href="#reverse_002c-areverse" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-reverse_002c-areverse" aria-hidden="true">TOC</a></span></h3>
<p>Reverse a clip.
</p>
<p>Warning: This filter requires memory to buffer the entire clip, so trimming
is suggested.
</p>
<a name="Examples-92"></a>
<h4 class="subsection">37.96.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-92" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-92" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Take the first 5 seconds of a clip, and reverse it.
<div class="example">
<pre class="example">trim=end=5,reverse
</pre></div>
</li></ul>
<a name="rotate"></a>
<h3 class="section">37.97 rotate<span class="pull-right"><a class="anchor hidden-xs" href="#rotate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-rotate" aria-hidden="true">TOC</a></span></h3>
<p>Rotate video by an arbitrary angle expressed in radians.
</p>
<p>The filter accepts the following options:
</p>
<p>A description of the optional parameters follows.
</p><dl compact="compact">
<dt><samp>angle, a</samp></dt>
<dd><p>Set an expression for the angle by which to rotate the input video
clockwise, expressed as a number of radians. A negative value will
result in a counter-clockwise rotation. By default it is set to "0".
</p>
<p>This expression is evaluated for each frame.
</p>
</dd>
<dt><samp>out_w, ow</samp></dt>
<dd><p>Set the output width expression, default value is "iw".
This expression is evaluated just once during configuration.
</p>
</dd>
<dt><samp>out_h, oh</samp></dt>
<dd><p>Set the output height expression, default value is "ih".
This expression is evaluated just once during configuration.
</p>
</dd>
<dt><samp>bilinear</samp></dt>
<dd><p>Enable bilinear interpolation if set to 1, a value of 0 disables
it. Default value is 1.
</p>
</dd>
<dt><samp>fillcolor, c</samp></dt>
<dd><p>Set the color used to fill the output area not covered by the rotated
image. For the general syntax of this option, check the "Color" section in the
ffmpeg-utils manual. If the special value "none" is selected then no
background is printed (useful for example if the background is never shown).
</p>
<p>Default value is "black".
</p></dd>
</dl>
<p>The expressions for the angle and the output size can contain the
following constants and functions:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>sequential number of the input frame, starting from 0. It is always NAN
before the first frame is filtered.
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>time in seconds of the input frame, it is set to 0 when the filter is
configured. It is always NAN before the first frame is filtered.
</p>
</dd>
<dt><samp>hsub</samp></dt>
<dt><samp>vsub</samp></dt>
<dd><p>horizontal and vertical chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><samp>in_w, iw</samp></dt>
<dt><samp>in_h, ih</samp></dt>
<dd><p>the input video width and height
</p>
</dd>
<dt><samp>out_w, ow</samp></dt>
<dt><samp>out_h, oh</samp></dt>
<dd><p>the output width and height, that is the size of the padded area as
specified by the <var>width</var> and <var>height</var> expressions
</p>
</dd>
<dt><samp>rotw(a)</samp></dt>
<dt><samp>roth(a)</samp></dt>
<dd><p>the minimal width/height required for completely containing the input
video rotated by <var>a</var> radians.
</p>
<p>These are only available when computing the <samp>out_w</samp> and
<samp>out_h</samp> expressions.
</p></dd>
</dl>
<a name="Examples-93"></a>
<h4 class="subsection">37.97.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-93" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-93" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Rotate the input by PI/6 radians clockwise:
<div class="example">
<pre class="example">rotate=PI/6
</pre></div>
</li><li> Rotate the input by PI/6 radians counter-clockwise:
<div class="example">
<pre class="example">rotate=-PI/6
</pre></div>
</li><li> Rotate the input by 45 degrees clockwise:
<div class="example">
<pre class="example">rotate=45*PI/180
</pre></div>
</li><li> Apply a constant rotation with period T, starting from an angle of PI/3:
<div class="example">
<pre class="example">rotate=PI/3+2*PI*t/T
</pre></div>
</li><li> Make the input video rotation oscillating with a period of T
seconds and an amplitude of A radians:
<div class="example">
<pre class="example">rotate=A*sin(2*PI/T*t)
</pre></div>
</li><li> Rotate the video, output size is chosen so that the whole rotating
input video is always completely contained in the output:
<div class="example">
<pre class="example">rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
</pre></div>
</li><li> Rotate the video, reduce the output size so that no background is ever
shown:
<div class="example">
<pre class="example">rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
</pre></div>
</li></ul>
<a name="Commands-6"></a>
<h4 class="subsection">37.97.2 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-6" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-6" aria-hidden="true">TOC</a></span></h4>
<p>The filter supports the following commands:
</p>
<dl compact="compact">
<dt><samp>a, angle</samp></dt>
<dd><p>Set the angle expression.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
</dl>
<a name="sab"></a>
<h3 class="section">37.98 sab<span class="pull-right"><a class="anchor hidden-xs" href="#sab" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sab" aria-hidden="true">TOC</a></span></h3>
<p>Apply Shape Adaptive Blur.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>luma_radius, lr</samp></dt>
<dd><p>Set luma blur filter strength, must be a value in range 0.1-4.0, default
value is 1.0. A greater value will result in a more blurred image, and
in slower processing.
</p>
</dd>
<dt><samp>luma_pre_filter_radius, lpfr</samp></dt>
<dd><p>Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
value is 1.0.
</p>
</dd>
<dt><samp>luma_strength, ls</samp></dt>
<dd><p>Set luma maximum difference between pixels to still be considered, must
be a value in the 0.1-100.0 range, default value is 1.0.
</p>
</dd>
<dt><samp>chroma_radius, cr</samp></dt>
<dd><p>Set chroma blur filter strength, must be a value in range 0.1-4.0. A
greater value will result in a more blurred image, and in slower
processing.
</p>
</dd>
<dt><samp>chroma_pre_filter_radius, cpfr</samp></dt>
<dd><p>Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
</p>
</dd>
<dt><samp>chroma_strength, cs</samp></dt>
<dd><p>Set chroma maximum difference between pixels to still be considered,
must be a value in the 0.1-100.0 range.
</p></dd>
</dl>
<p>Each chroma option value, if not explicitly specified, is set to the
corresponding luma option value.
</p>
<a name="scale"></a><a name="scale-1"></a>
<h3 class="section">37.99 scale<span class="pull-right"><a class="anchor hidden-xs" href="#scale-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-scale-1" aria-hidden="true">TOC</a></span></h3>
<p>Scale (resize) the input video, using the libswscale library.
</p>
<p>The scale filter forces the output display aspect ratio to be the same
of the input, by changing the output sample aspect ratio.
</p>
<p>If the input image format is different from the format requested by
the next filter, the scale filter will convert the input to the
requested format.
</p>
<a name="Options-69"></a>
<h4 class="subsection">37.99.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-69" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-69" aria-hidden="true">TOC</a></span></h4>
<p>The filter accepts the following options, or any of the options
supported by the libswscale scaler.
</p>
<p>See <a href="ffmpeg-scaler.html#scaler_005foptions">(ffmpeg-scaler)the ffmpeg-scaler manual</a> for
the complete list of scaler options.
</p>
<dl compact="compact">
<dt><samp>width, w</samp></dt>
<dt><samp>height, h</samp></dt>
<dd><p>Set the output video dimension expression. Default value is the input
dimension.
</p>
<p>If the value is 0, the input width is used for the output.
</p>
<p>If one of the values is -1, the scale filter will use a value that
maintains the aspect ratio of the input image, calculated from the
other specified dimension. If both of them are -1, the input size is
used
</p>
<p>If one of the values is -n with n > 1, the scale filter will also use a value
that maintains the aspect ratio of the input image, calculated from the other
specified dimension. After that it will, however, make sure that the calculated
dimension is divisible by n and adjust the value if necessary.
</p>
<p>See below for the list of accepted constants for use in the dimension
expression.
</p>
</dd>
<dt><samp>interl</samp></dt>
<dd><p>Set the interlacing mode. It accepts the following values:
</p>
<dl compact="compact">
<dt>‘<samp>1</samp>’</dt>
<dd><p>Force interlaced aware scaling.
</p>
</dd>
<dt>‘<samp>0</samp>’</dt>
<dd><p>Do not apply interlaced scaling.
</p>
</dd>
<dt>‘<samp>-1</samp>’</dt>
<dd><p>Select interlaced aware scaling depending on whether the source frames
are flagged as interlaced or not.
</p></dd>
</dl>
<p>Default value is ‘<samp>0</samp>’.
</p>
</dd>
<dt><samp>flags</samp></dt>
<dd><p>Set libswscale scaling flags. See
<a href="ffmpeg-scaler.html#sws_005fflags">(ffmpeg-scaler)the ffmpeg-scaler manual</a> for the
complete list of values. If not explicitly specified the filter applies
the default flags.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set the video size. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
</dd>
<dt><samp>in_color_matrix</samp></dt>
<dt><samp>out_color_matrix</samp></dt>
<dd><p>Set in/output YCbCr color space type.
</p>
<p>This allows the autodetected value to be overridden as well as allows forcing
a specific value used for the output and encoder.
</p>
<p>If not specified, the color space type depends on the pixel format.
</p>
<p>Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Choose automatically.
</p>
</dd>
<dt>‘<samp>bt709</samp>’</dt>
<dd><p>Format conforming to International Telecommunication Union (ITU)
Recommendation BT.709.
</p>
</dd>
<dt>‘<samp>fcc</samp>’</dt>
<dd><p>Set color space conforming to the United States Federal Communications
Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
</p>
</dd>
<dt>‘<samp>bt601</samp>’</dt>
<dd><p>Set color space conforming to:
</p>
<ul>
<li> ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
</li><li> ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
</li><li> Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
</li></ul>
</dd>
<dt>‘<samp>smpte240m</samp>’</dt>
<dd><p>Set color space conforming to SMPTE ST 240:1999.
</p></dd>
</dl>
</dd>
<dt><samp>in_range</samp></dt>
<dt><samp>out_range</samp></dt>
<dd><p>Set in/output YCbCr sample range.
</p>
<p>This allows the autodetected value to be overridden as well as allows forcing
a specific value used for the output and encoder. If not specified, the
range depends on the pixel format. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Choose automatically.
</p>
</dd>
<dt>‘<samp>jpeg/full/pc</samp>’</dt>
<dd><p>Set full range (0-255 in case of 8-bit luma).
</p>
</dd>
<dt>‘<samp>mpeg/tv</samp>’</dt>
<dd><p>Set "MPEG" range (16-235 in case of 8-bit luma).
</p></dd>
</dl>
</dd>
<dt><samp>force_original_aspect_ratio</samp></dt>
<dd><p>Enable decreasing or increasing output video width or height if necessary to
keep the original aspect ratio. Possible values:
</p>
<dl compact="compact">
<dt>‘<samp>disable</samp>’</dt>
<dd><p>Scale the video as specified and disable this feature.
</p>
</dd>
<dt>‘<samp>decrease</samp>’</dt>
<dd><p>The output video dimensions will automatically be decreased if needed.
</p>
</dd>
<dt>‘<samp>increase</samp>’</dt>
<dd><p>The output video dimensions will automatically be increased if needed.
</p>
</dd>
</dl>
<p>One useful instance of this option is that when you know a specific device’s
maximum allowed resolution, you can use this to limit the output video to
that, while retaining the aspect ratio. For example, device A allows
1280x720 playback, and your video is 1920x800. Using this option (set it to
decrease) and specifying 1280x720 to the command line makes the output
1280x533.
</p>
<p>Please note that this is a different thing than specifying -1 for <samp>w</samp>
or <samp>h</samp>, you still need to specify the output resolution for this option
to work.
</p>
</dd>
</dl>
<p>The values of the <samp>w</samp> and <samp>h</samp> options are expressions
containing the following constants:
</p>
<dl compact="compact">
<dt><var>in_w</var></dt>
<dt><var>in_h</var></dt>
<dd><p>The input width and height
</p>
</dd>
<dt><var>iw</var></dt>
<dt><var>ih</var></dt>
<dd><p>These are the same as <var>in_w</var> and <var>in_h</var>.
</p>
</dd>
<dt><var>out_w</var></dt>
<dt><var>out_h</var></dt>
<dd><p>The output (scaled) width and height
</p>
</dd>
<dt><var>ow</var></dt>
<dt><var>oh</var></dt>
<dd><p>These are the same as <var>out_w</var> and <var>out_h</var>
</p>
</dd>
<dt><var>a</var></dt>
<dd><p>The same as <var>iw</var> / <var>ih</var>
</p>
</dd>
<dt><var>sar</var></dt>
<dd><p>input sample aspect ratio
</p>
</dd>
<dt><var>dar</var></dt>
<dd><p>The input display aspect ratio. Calculated from <code>(iw / ih) * sar</code>.
</p>
</dd>
<dt><var>hsub</var></dt>
<dt><var>vsub</var></dt>
<dd><p>horizontal and vertical input chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p>
</dd>
<dt><var>ohsub</var></dt>
<dt><var>ovsub</var></dt>
<dd><p>horizontal and vertical output chroma subsample values. For example for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p></dd>
</dl>
<a name="Examples-94"></a>
<h4 class="subsection">37.99.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-94" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-94" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Scale the input video to a size of 200x100
<div class="example">
<pre class="example">scale=w=200:h=100
</pre></div>
<p>This is equivalent to:
</p><div class="example">
<pre class="example">scale=200:100
</pre></div>
<p>or:
</p><div class="example">
<pre class="example">scale=200x100
</pre></div>
</li><li> Specify a size abbreviation for the output size:
<div class="example">
<pre class="example">scale=qcif
</pre></div>
<p>which can also be written as:
</p><div class="example">
<pre class="example">scale=size=qcif
</pre></div>
</li><li> Scale the input to 2x:
<div class="example">
<pre class="example">scale=w=2*iw:h=2*ih
</pre></div>
</li><li> The above is the same as:
<div class="example">
<pre class="example">scale=2*in_w:2*in_h
</pre></div>
</li><li> Scale the input to 2x with forced interlaced scaling:
<div class="example">
<pre class="example">scale=2*iw:2*ih:interl=1
</pre></div>
</li><li> Scale the input to half size:
<div class="example">
<pre class="example">scale=w=iw/2:h=ih/2
</pre></div>
</li><li> Increase the width, and set the height to the same size:
<div class="example">
<pre class="example">scale=3/2*iw:ow
</pre></div>
</li><li> Seek Greek harmony:
<div class="example">
<pre class="example">scale=iw:1/PHI*iw
scale=ih*PHI:ih
</pre></div>
</li><li> Increase the height, and set the width to 3/2 of the height:
<div class="example">
<pre class="example">scale=w=3/2*oh:h=3/5*ih
</pre></div>
</li><li> Increase the size, making the size a multiple of the chroma
subsample values:
<div class="example">
<pre class="example">scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
</pre></div>
</li><li> Increase the width to a maximum of 500 pixels,
keeping the same aspect ratio as the input:
<div class="example">
<pre class="example">scale=w='min(500\, iw*3/2):h=-1'
</pre></div>
</li></ul>
<a name="Commands-7"></a>
<h4 class="subsection">37.99.3 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-7" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-7" aria-hidden="true">TOC</a></span></h4>
<p>This filter supports the following commands:
</p><dl compact="compact">
<dt><samp>width, w</samp></dt>
<dt><samp>height, h</samp></dt>
<dd><p>Set the output video dimension expression.
The command accepts the same syntax of the corresponding option.
</p>
<p>If the specified expression is not valid, it is kept at its current
value.
</p></dd>
</dl>
<a name="scale2ref"></a>
<h3 class="section">37.100 scale2ref<span class="pull-right"><a class="anchor hidden-xs" href="#scale2ref" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-scale2ref" aria-hidden="true">TOC</a></span></h3>
<p>Scale (resize) the input video, based on a reference video.
</p>
<p>See the scale filter for available options, scale2ref supports the same but
uses the reference video instead of the main input as basis.
</p>
<a name="Examples-95"></a>
<h4 class="subsection">37.100.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-95" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-95" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Scale a subtitle stream to match the main video in size before overlaying
<div class="example">
<pre class="example">'scale2ref[b][a];[a][b]overlay'
</pre></div>
</li></ul>
<a name="separatefields"></a>
<h3 class="section">37.101 separatefields<span class="pull-right"><a class="anchor hidden-xs" href="#separatefields" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-separatefields" aria-hidden="true">TOC</a></span></h3>
<p>The <code>separatefields</code> takes a frame-based video input and splits
each frame into its components fields, producing a new half height clip
with twice the frame rate and twice the frame count.
</p>
<p>This filter use field-dominance information in frame to decide which
of each pair of fields to place first in the output.
If it gets it wrong use <a href="#setfield">setfield</a> filter before <code>separatefields</code> filter.
</p>
<a name="setdar_002c-setsar"></a>
<h3 class="section">37.102 setdar, setsar<span class="pull-right"><a class="anchor hidden-xs" href="#setdar_002c-setsar" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-setdar_002c-setsar" aria-hidden="true">TOC</a></span></h3>
<p>The <code>setdar</code> filter sets the Display Aspect Ratio for the filter
output video.
</p>
<p>This is done by changing the specified Sample (aka Pixel) Aspect
Ratio, according to the following equation:
</p><div class="example">
<pre class="example"><var>DAR</var> = <var>HORIZONTAL_RESOLUTION</var> / <var>VERTICAL_RESOLUTION</var> * <var>SAR</var>
</pre></div>
<p>Keep in mind that the <code>setdar</code> filter does not modify the pixel
dimensions of the video frame. Also, the display aspect ratio set by
this filter may be changed by later filters in the filterchain,
e.g. in case of scaling or if another "setdar" or a "setsar" filter is
applied.
</p>
<p>The <code>setsar</code> filter sets the Sample (aka Pixel) Aspect Ratio for
the filter output video.
</p>
<p>Note that as a consequence of the application of this filter, the
output display aspect ratio will change according to the equation
above.
</p>
<p>Keep in mind that the sample aspect ratio set by the <code>setsar</code>
filter may be changed by later filters in the filterchain, e.g. if
another "setsar" or a "setdar" filter is applied.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>r, ratio, dar (<code>setdar</code> only), sar (<code>setsar</code> only)</samp></dt>
<dd><p>Set the aspect ratio used by the filter.
</p>
<p>The parameter can be a floating point number string, an expression, or
a string of the form <var>num</var>:<var>den</var>, where <var>num</var> and
<var>den</var> are the numerator and denominator of the aspect ratio. If
the parameter is not specified, it is assumed the value "0".
In case the form "<var>num</var>:<var>den</var>" is used, the <code>:</code> character
should be escaped.
</p>
</dd>
<dt><samp>max</samp></dt>
<dd><p>Set the maximum integer value to use for expressing numerator and
denominator when reducing the expressed aspect ratio to a rational.
Default value is <code>100</code>.
</p>
</dd>
</dl>
<p>The parameter <var>sar</var> is an expression containing
the following constants:
</p>
<dl compact="compact">
<dt><samp>E, PI, PHI</samp></dt>
<dd><p>These are approximated values for the mathematical constants e
(Euler’s number), pi (Greek pi), and phi (the golden ratio).
</p>
</dd>
<dt><samp>w, h</samp></dt>
<dd><p>The input width and height.
</p>
</dd>
<dt><samp>a</samp></dt>
<dd><p>These are the same as <var>w</var> / <var>h</var>.
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>The input sample aspect ratio.
</p>
</dd>
<dt><samp>dar</samp></dt>
<dd><p>The input display aspect ratio. It is the same as
(<var>w</var> / <var>h</var>) * <var>sar</var>.
</p>
</dd>
<dt><samp>hsub, vsub</samp></dt>
<dd><p>Horizontal and vertical chroma subsample values. For example, for the
pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
</p></dd>
</dl>
<a name="Examples-96"></a>
<h4 class="subsection">37.102.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-96" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-96" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> To change the display aspect ratio to 16:9, specify one of the following:
<div class="example">
<pre class="example">setdar=dar=1.77777
setdar=dar=16/9
setdar=dar=1.77777
</pre></div>
</li><li> To change the sample aspect ratio to 10:11, specify:
<div class="example">
<pre class="example">setsar=sar=10/11
</pre></div>
</li><li> To set a display aspect ratio of 16:9, and specify a maximum integer value of
1000 in the aspect ratio reduction, use the command:
<div class="example">
<pre class="example">setdar=ratio=16/9:max=1000
</pre></div>
</li></ul>
<a name="setfield"></a><a name="setfield-1"></a>
<h3 class="section">37.103 setfield<span class="pull-right"><a class="anchor hidden-xs" href="#setfield-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-setfield-1" aria-hidden="true">TOC</a></span></h3>
<p>Force field for the output video frame.
</p>
<p>The <code>setfield</code> filter marks the interlace type field for the
output frames. It does not change the input frame, but only sets the
corresponding property, which affects how the frame is treated by
following filters (e.g. <code>fieldorder</code> or <code>yadif</code>).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>Keep the same field property.
</p>
</dd>
<dt>‘<samp>bff</samp>’</dt>
<dd><p>Mark the frame as bottom-field-first.
</p>
</dd>
<dt>‘<samp>tff</samp>’</dt>
<dd><p>Mark the frame as top-field-first.
</p>
</dd>
<dt>‘<samp>prog</samp>’</dt>
<dd><p>Mark the frame as progressive.
</p></dd>
</dl>
</dd>
</dl>
<a name="showinfo"></a>
<h3 class="section">37.104 showinfo<span class="pull-right"><a class="anchor hidden-xs" href="#showinfo" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showinfo" aria-hidden="true">TOC</a></span></h3>
<p>Show a line containing various information for each input video frame.
The input video is not modified.
</p>
<p>The shown line contains a sequence of key/value pairs of the form
<var>key</var>:<var>value</var>.
</p>
<p>The following values are shown in the output:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>The (sequential) number of the input frame, starting from 0.
</p>
</dd>
<dt><samp>pts</samp></dt>
<dd><p>The Presentation TimeStamp of the input frame, expressed as a number of
time base units. The time base unit depends on the filter input pad.
</p>
</dd>
<dt><samp>pts_time</samp></dt>
<dd><p>The Presentation TimeStamp of the input frame, expressed as a number of
seconds.
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>The position of the frame in the input stream, or -1 if this information is
unavailable and/or meaningless (for example in case of synthetic video).
</p>
</dd>
<dt><samp>fmt</samp></dt>
<dd><p>The pixel format name.
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>The sample aspect ratio of the input frame, expressed in the form
<var>num</var>/<var>den</var>.
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>The size of the input frame. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
</dd>
<dt><samp>i</samp></dt>
<dd><p>The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
for bottom field first).
</p>
</dd>
<dt><samp>iskey</samp></dt>
<dd><p>This is 1 if the frame is a key frame, 0 otherwise.
</p>
</dd>
<dt><samp>type</samp></dt>
<dd><p>The picture type of the input frame ("I" for an I-frame, "P" for a
P-frame, "B" for a B-frame, or "?" for an unknown type).
Also refer to the documentation of the <code>AVPictureType</code> enum and of
the <code>av_get_picture_type_char</code> function defined in
<samp>libavutil/avutil.h</samp>.
</p>
</dd>
<dt><samp>checksum</samp></dt>
<dd><p>The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
</p>
</dd>
<dt><samp>plane_checksum</samp></dt>
<dd><p>The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
expressed in the form "[<var>c0</var> <var>c1</var> <var>c2</var> <var>c3</var>]".
</p></dd>
</dl>
<a name="showpalette"></a>
<h3 class="section">37.105 showpalette<span class="pull-right"><a class="anchor hidden-xs" href="#showpalette" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showpalette" aria-hidden="true">TOC</a></span></h3>
<p>Displays the 256 colors palette of each frame. This filter is only relevant for
<var>pal8</var> pixel format frames.
</p>
<p>It accepts the following option:
</p>
<dl compact="compact">
<dt><samp>s</samp></dt>
<dd><p>Set the size of the box used to represent one palette color entry. Default is
<code>30</code> (for a <code>30x30</code> pixel box).
</p></dd>
</dl>
<a name="shuffleplanes"></a>
<h3 class="section">37.106 shuffleplanes<span class="pull-right"><a class="anchor hidden-xs" href="#shuffleplanes" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-shuffleplanes" aria-hidden="true">TOC</a></span></h3>
<p>Reorder and/or duplicate video planes.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>map0</samp></dt>
<dd><p>The index of the input plane to be used as the first output plane.
</p>
</dd>
<dt><samp>map1</samp></dt>
<dd><p>The index of the input plane to be used as the second output plane.
</p>
</dd>
<dt><samp>map2</samp></dt>
<dd><p>The index of the input plane to be used as the third output plane.
</p>
</dd>
<dt><samp>map3</samp></dt>
<dd><p>The index of the input plane to be used as the fourth output plane.
</p>
</dd>
</dl>
<p>The first plane has the index 0. The default is to keep the input unchanged.
</p>
<p>Swap the second and third planes of the input:
</p><div class="example">
<pre class="example">ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
</pre></div>
<a name="signalstats"></a><a name="signalstats-1"></a>
<h3 class="section">37.107 signalstats<span class="pull-right"><a class="anchor hidden-xs" href="#signalstats-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-signalstats-1" aria-hidden="true">TOC</a></span></h3>
<p>Evaluate various visual metrics that assist in determining issues associated
with the digitization of analog video media.
</p>
<p>By default the filter will log these metadata values:
</p>
<dl compact="compact">
<dt><samp>YMIN</samp></dt>
<dd><p>Display the minimal Y value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>YLOW</samp></dt>
<dd><p>Display the Y value at the 10% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>YAVG</samp></dt>
<dd><p>Display the average Y value within the input frame. Expressed in range of
[0-255].
</p>
</dd>
<dt><samp>YHIGH</samp></dt>
<dd><p>Display the Y value at the 90% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>YMAX</samp></dt>
<dd><p>Display the maximum Y value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>UMIN</samp></dt>
<dd><p>Display the minimal U value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>ULOW</samp></dt>
<dd><p>Display the U value at the 10% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>UAVG</samp></dt>
<dd><p>Display the average U value within the input frame. Expressed in range of
[0-255].
</p>
</dd>
<dt><samp>UHIGH</samp></dt>
<dd><p>Display the U value at the 90% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>UMAX</samp></dt>
<dd><p>Display the maximum U value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>VMIN</samp></dt>
<dd><p>Display the minimal V value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>VLOW</samp></dt>
<dd><p>Display the V value at the 10% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>VAVG</samp></dt>
<dd><p>Display the average V value within the input frame. Expressed in range of
[0-255].
</p>
</dd>
<dt><samp>VHIGH</samp></dt>
<dd><p>Display the V value at the 90% percentile within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>VMAX</samp></dt>
<dd><p>Display the maximum V value contained within the input frame. Expressed in
range of [0-255].
</p>
</dd>
<dt><samp>SATMIN</samp></dt>
<dd><p>Display the minimal saturation value contained within the input frame.
Expressed in range of [0-~181.02].
</p>
</dd>
<dt><samp>SATLOW</samp></dt>
<dd><p>Display the saturation value at the 10% percentile within the input frame.
Expressed in range of [0-~181.02].
</p>
</dd>
<dt><samp>SATAVG</samp></dt>
<dd><p>Display the average saturation value within the input frame. Expressed in range
of [0-~181.02].
</p>
</dd>
<dt><samp>SATHIGH</samp></dt>
<dd><p>Display the saturation value at the 90% percentile within the input frame.
Expressed in range of [0-~181.02].
</p>
</dd>
<dt><samp>SATMAX</samp></dt>
<dd><p>Display the maximum saturation value contained within the input frame.
Expressed in range of [0-~181.02].
</p>
</dd>
<dt><samp>HUEMED</samp></dt>
<dd><p>Display the median value for hue within the input frame. Expressed in range of
[0-360].
</p>
</dd>
<dt><samp>HUEAVG</samp></dt>
<dd><p>Display the average value for hue within the input frame. Expressed in range of
[0-360].
</p>
</dd>
<dt><samp>YDIF</samp></dt>
<dd><p>Display the average of sample value difference between all values of the Y
plane in the current frame and corresponding values of the previous input frame.
Expressed in range of [0-255].
</p>
</dd>
<dt><samp>UDIF</samp></dt>
<dd><p>Display the average of sample value difference between all values of the U
plane in the current frame and corresponding values of the previous input frame.
Expressed in range of [0-255].
</p>
</dd>
<dt><samp>VDIF</samp></dt>
<dd><p>Display the average of sample value difference between all values of the V
plane in the current frame and corresponding values of the previous input frame.
Expressed in range of [0-255].
</p></dd>
</dl>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>stat</samp></dt>
<dt><samp>out</samp></dt>
<dd>
<p><samp>stat</samp> specify an additional form of image analysis.
<samp>out</samp> output video with the specified type of pixel highlighted.
</p>
<p>Both options accept the following values:
</p>
<dl compact="compact">
<dt>‘<samp>tout</samp>’</dt>
<dd><p>Identify <var>temporal outliers</var> pixels. A <var>temporal outlier</var> is a pixel
unlike the neighboring pixels of the same field. Examples of temporal outliers
include the results of video dropouts, head clogs, or tape tracking issues.
</p>
</dd>
<dt>‘<samp>vrep</samp>’</dt>
<dd><p>Identify <var>vertical line repetition</var>. Vertical line repetition includes
similar rows of pixels within a frame. In born-digital video vertical line
repetition is common, but this pattern is uncommon in video digitized from an
analog source. When it occurs in video that results from the digitization of an
analog source it can indicate concealment from a dropout compensator.
</p>
</dd>
<dt>‘<samp>brng</samp>’</dt>
<dd><p>Identify pixels that fall outside of legal broadcast range.
</p></dd>
</dl>
</dd>
<dt><samp>color, c</samp></dt>
<dd><p>Set the highlight color for the <samp>out</samp> option. The default color is
yellow.
</p></dd>
</dl>
<a name="Examples-97"></a>
<h4 class="subsection">37.107.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-97" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-97" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Output data of various video metrics:
<div class="example">
<pre class="example">ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
</pre></div>
</li><li> Output specific data about the minimum and maximum values of the Y plane per frame:
<div class="example">
<pre class="example">ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
</pre></div>
</li><li> Playback video while highlighting pixels that are outside of broadcast range in red.
<div class="example">
<pre class="example">ffplay example.mov -vf signalstats="out=brng:color=red"
</pre></div>
</li><li> Playback video with signalstats metadata drawn over the frame.
<div class="example">
<pre class="example">ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
</pre></div>
<p>The contents of signalstat_drawtext.txt used in the command are:
</p><div class="example">
<pre class="example">time %{pts:hms}
Y (%{metadata:lavfi.signalstats.YMIN}-%{metadata:lavfi.signalstats.YMAX})
U (%{metadata:lavfi.signalstats.UMIN}-%{metadata:lavfi.signalstats.UMAX})
V (%{metadata:lavfi.signalstats.VMIN}-%{metadata:lavfi.signalstats.VMAX})
saturation maximum: %{metadata:lavfi.signalstats.SATMAX}
</pre></div>
</li></ul>
<a name="smartblur"></a><a name="smartblur-1"></a>
<h3 class="section">37.108 smartblur<span class="pull-right"><a class="anchor hidden-xs" href="#smartblur-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-smartblur-1" aria-hidden="true">TOC</a></span></h3>
<p>Blur the input video without impacting the outlines.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>luma_radius, lr</samp></dt>
<dd><p>Set the luma radius. The option value must be a float number in
the range [0.1,5.0] that specifies the variance of the gaussian filter
used to blur the image (slower if larger). Default value is 1.0.
</p>
</dd>
<dt><samp>luma_strength, ls</samp></dt>
<dd><p>Set the luma strength. The option value must be a float number
in the range [-1.0,1.0] that configures the blurring. A value included
in [0.0,1.0] will blur the image whereas a value included in
[-1.0,0.0] will sharpen the image. Default value is 1.0.
</p>
</dd>
<dt><samp>luma_threshold, lt</samp></dt>
<dd><p>Set the luma threshold used as a coefficient to determine
whether a pixel should be blurred or not. The option value must be an
integer in the range [-30,30]. A value of 0 will filter all the image,
a value included in [0,30] will filter flat areas and a value included
in [-30,0] will filter edges. Default value is 0.
</p>
</dd>
<dt><samp>chroma_radius, cr</samp></dt>
<dd><p>Set the chroma radius. The option value must be a float number in
the range [0.1,5.0] that specifies the variance of the gaussian filter
used to blur the image (slower if larger). Default value is 1.0.
</p>
</dd>
<dt><samp>chroma_strength, cs</samp></dt>
<dd><p>Set the chroma strength. The option value must be a float number
in the range [-1.0,1.0] that configures the blurring. A value included
in [0.0,1.0] will blur the image whereas a value included in
[-1.0,0.0] will sharpen the image. Default value is 1.0.
</p>
</dd>
<dt><samp>chroma_threshold, ct</samp></dt>
<dd><p>Set the chroma threshold used as a coefficient to determine
whether a pixel should be blurred or not. The option value must be an
integer in the range [-30,30]. A value of 0 will filter all the image,
a value included in [0,30] will filter flat areas and a value included
in [-30,0] will filter edges. Default value is 0.
</p></dd>
</dl>
<p>If a chroma option is not explicitly set, the corresponding luma value
is set.
</p>
<a name="ssim"></a>
<h3 class="section">37.109 ssim<span class="pull-right"><a class="anchor hidden-xs" href="#ssim" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ssim" aria-hidden="true">TOC</a></span></h3>
<p>Obtain the SSIM (Structural SImilarity Metric) between two input videos.
</p>
<p>This filter takes in input two input videos, the first input is
considered the "main" source and is passed unchanged to the
output. The second input is used as a "reference" video for computing
the SSIM.
</p>
<p>Both video inputs must have the same resolution and pixel format for
this filter to work correctly. Also it assumes that both inputs
have the same number of frames, which are compared one by one.
</p>
<p>The filter stores the calculated SSIM of each frame.
</p>
<p>The description of the accepted parameters follows.
</p>
<dl compact="compact">
<dt><samp>stats_file, f</samp></dt>
<dd><p>If specified the filter will use the named file to save the SSIM of
each individual frame.
</p></dd>
</dl>
<p>The file printed if <var>stats_file</var> is selected, contains a sequence of
key/value pairs of the form <var>key</var>:<var>value</var> for each compared
couple of frames.
</p>
<p>A description of each shown parameter follows:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>sequential number of the input frame, starting from 1
</p>
</dd>
<dt><samp>Y, U, V, R, G, B</samp></dt>
<dd><p>SSIM of the compared frames for the component specified by the suffix.
</p>
</dd>
<dt><samp>All</samp></dt>
<dd><p>SSIM of the compared frames for the whole frame.
</p>
</dd>
<dt><samp>dB</samp></dt>
<dd><p>Same as above but in dB representation.
</p></dd>
</dl>
<p>For example:
</p><div class="example">
<pre class="example">movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
[main][ref] ssim="stats_file=stats.log" [out]
</pre></div>
<p>On this example the input file being processed is compared with the
reference file <samp>ref_movie.mpg</samp>. The SSIM of each individual frame
is stored in <samp>stats.log</samp>.
</p>
<p>Another example with both psnr and ssim at same time:
</p><div class="example">
<pre class="example">ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
</pre></div>
<a name="stereo3d"></a>
<h3 class="section">37.110 stereo3d<span class="pull-right"><a class="anchor hidden-xs" href="#stereo3d" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-stereo3d" aria-hidden="true">TOC</a></span></h3>
<p>Convert between different stereoscopic image formats.
</p>
<p>The filters accept the following options:
</p>
<dl compact="compact">
<dt><samp>in</samp></dt>
<dd><p>Set stereoscopic image format of input.
</p>
<p>Available values for input image formats are:
</p><dl compact="compact">
<dt>‘<samp>sbsl</samp>’</dt>
<dd><p>side by side parallel (left eye left, right eye right)
</p>
</dd>
<dt>‘<samp>sbsr</samp>’</dt>
<dd><p>side by side crosseye (right eye left, left eye right)
</p>
</dd>
<dt>‘<samp>sbs2l</samp>’</dt>
<dd><p>side by side parallel with half width resolution
(left eye left, right eye right)
</p>
</dd>
<dt>‘<samp>sbs2r</samp>’</dt>
<dd><p>side by side crosseye with half width resolution
(right eye left, left eye right)
</p>
</dd>
<dt>‘<samp>abl</samp>’</dt>
<dd><p>above-below (left eye above, right eye below)
</p>
</dd>
<dt>‘<samp>abr</samp>’</dt>
<dd><p>above-below (right eye above, left eye below)
</p>
</dd>
<dt>‘<samp>ab2l</samp>’</dt>
<dd><p>above-below with half height resolution
(left eye above, right eye below)
</p>
</dd>
<dt>‘<samp>ab2r</samp>’</dt>
<dd><p>above-below with half height resolution
(right eye above, left eye below)
</p>
</dd>
<dt>‘<samp>al</samp>’</dt>
<dd><p>alternating frames (left eye first, right eye second)
</p>
</dd>
<dt>‘<samp>ar</samp>’</dt>
<dd><p>alternating frames (right eye first, left eye second)
</p>
<p>Default value is ‘<samp>sbsl</samp>’.
</p></dd>
</dl>
</dd>
<dt><samp>out</samp></dt>
<dd><p>Set stereoscopic image format of output.
</p>
<p>Available values for output image formats are all the input formats as well as:
</p><dl compact="compact">
<dt>‘<samp>arbg</samp>’</dt>
<dd><p>anaglyph red/blue gray
(red filter on left eye, blue filter on right eye)
</p>
</dd>
<dt>‘<samp>argg</samp>’</dt>
<dd><p>anaglyph red/green gray
(red filter on left eye, green filter on right eye)
</p>
</dd>
<dt>‘<samp>arcg</samp>’</dt>
<dd><p>anaglyph red/cyan gray
(red filter on left eye, cyan filter on right eye)
</p>
</dd>
<dt>‘<samp>arch</samp>’</dt>
<dd><p>anaglyph red/cyan half colored
(red filter on left eye, cyan filter on right eye)
</p>
</dd>
<dt>‘<samp>arcc</samp>’</dt>
<dd><p>anaglyph red/cyan color
(red filter on left eye, cyan filter on right eye)
</p>
</dd>
<dt>‘<samp>arcd</samp>’</dt>
<dd><p>anaglyph red/cyan color optimized with the least squares projection of dubois
(red filter on left eye, cyan filter on right eye)
</p>
</dd>
<dt>‘<samp>agmg</samp>’</dt>
<dd><p>anaglyph green/magenta gray
(green filter on left eye, magenta filter on right eye)
</p>
</dd>
<dt>‘<samp>agmh</samp>’</dt>
<dd><p>anaglyph green/magenta half colored
(green filter on left eye, magenta filter on right eye)
</p>
</dd>
<dt>‘<samp>agmc</samp>’</dt>
<dd><p>anaglyph green/magenta colored
(green filter on left eye, magenta filter on right eye)
</p>
</dd>
<dt>‘<samp>agmd</samp>’</dt>
<dd><p>anaglyph green/magenta color optimized with the least squares projection of dubois
(green filter on left eye, magenta filter on right eye)
</p>
</dd>
<dt>‘<samp>aybg</samp>’</dt>
<dd><p>anaglyph yellow/blue gray
(yellow filter on left eye, blue filter on right eye)
</p>
</dd>
<dt>‘<samp>aybh</samp>’</dt>
<dd><p>anaglyph yellow/blue half colored
(yellow filter on left eye, blue filter on right eye)
</p>
</dd>
<dt>‘<samp>aybc</samp>’</dt>
<dd><p>anaglyph yellow/blue colored
(yellow filter on left eye, blue filter on right eye)
</p>
</dd>
<dt>‘<samp>aybd</samp>’</dt>
<dd><p>anaglyph yellow/blue color optimized with the least squares projection of dubois
(yellow filter on left eye, blue filter on right eye)
</p>
</dd>
<dt>‘<samp>irl</samp>’</dt>
<dd><p>interleaved rows (left eye has top row, right eye starts on next row)
</p>
</dd>
<dt>‘<samp>irr</samp>’</dt>
<dd><p>interleaved rows (right eye has top row, left eye starts on next row)
</p>
</dd>
<dt>‘<samp>ml</samp>’</dt>
<dd><p>mono output (left eye only)
</p>
</dd>
<dt>‘<samp>mr</samp>’</dt>
<dd><p>mono output (right eye only)
</p></dd>
</dl>
<p>Default value is ‘<samp>arcd</samp>’.
</p></dd>
</dl>
<a name="Examples-98"></a>
<h4 class="subsection">37.110.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-98" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-98" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Convert input video from side by side parallel to anaglyph yellow/blue dubois:
<div class="example">
<pre class="example">stereo3d=sbsl:aybd
</pre></div>
</li><li> Convert input video from above below (left eye above, right eye below) to side by side crosseye.
<div class="example">
<pre class="example">stereo3d=abl:sbsr
</pre></div>
</li></ul>
<a name="spp"></a><a name="spp-1"></a>
<h3 class="section">37.111 spp<span class="pull-right"><a class="anchor hidden-xs" href="#spp-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-spp-1" aria-hidden="true">TOC</a></span></h3>
<p>Apply a simple postprocessing filter that compresses and decompresses the image
at several (or - in the case of <samp>quality</samp> level <code>6</code> - all) shifts
and average the results.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>quality</samp></dt>
<dd><p>Set quality. This option defines the number of levels for averaging. It accepts
an integer in the range 0-6. If set to <code>0</code>, the filter will have no
effect. A value of <code>6</code> means the higher quality. For each increment of
that value the speed drops by a factor of approximately 2. Default value is
<code>3</code>.
</p>
</dd>
<dt><samp>qp</samp></dt>
<dd><p>Force a constant quantization parameter. If not set, the filter will use the QP
from the video stream (if available).
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set thresholding mode. Available modes are:
</p>
<dl compact="compact">
<dt>‘<samp>hard</samp>’</dt>
<dd><p>Set hard thresholding (default).
</p></dd>
<dt>‘<samp>soft</samp>’</dt>
<dd><p>Set soft thresholding (better de-ringing effect, but likely blurrier).
</p></dd>
</dl>
</dd>
<dt><samp>use_bframe_qp</samp></dt>
<dd><p>Enable the use of the QP from the B-Frames if set to <code>1</code>. Using this
option may cause flicker since the B-Frames have often larger QP. Default is
<code>0</code> (not enabled).
</p></dd>
</dl>
<a name="subtitles"></a><a name="subtitles-1"></a>
<h3 class="section">37.112 subtitles<span class="pull-right"><a class="anchor hidden-xs" href="#subtitles-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-subtitles-1" aria-hidden="true">TOC</a></span></h3>
<p>Draw subtitles on top of input video using the libass library.
</p>
<p>To enable compilation of this filter you need to configure FFmpeg with
<code>--enable-libass</code>. This filter also requires a build with libavcodec and
libavformat to convert the passed subtitles file to ASS (Advanced Substation
Alpha) subtitles format.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>filename, f</samp></dt>
<dd><p>Set the filename of the subtitle file to read. It must be specified.
</p>
</dd>
<dt><samp>original_size</samp></dt>
<dd><p>Specify the size of the original video, the video for which the ASS file
was composed. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
correctly scale the fonts if the aspect ratio has been changed.
</p>
</dd>
<dt><samp>fontsdir</samp></dt>
<dd><p>Set a directory path containing fonts that can be used by the filter.
These fonts will be used in addition to whatever the font provider uses.
</p>
</dd>
<dt><samp>charenc</samp></dt>
<dd><p>Set subtitles input character encoding. <code>subtitles</code> filter only. Only
useful if not UTF-8.
</p>
</dd>
<dt><samp>stream_index, si</samp></dt>
<dd><p>Set subtitles stream index. <code>subtitles</code> filter only.
</p>
</dd>
<dt><samp>force_style</samp></dt>
<dd><p>Override default style or script info parameters of the subtitles. It accepts a
string containing ASS style format <code>KEY=VALUE</code> couples separated by ",".
</p></dd>
</dl>
<p>If the first key is not specified, it is assumed that the first value
specifies the <samp>filename</samp>.
</p>
<p>For example, to render the file <samp>sub.srt</samp> on top of the input
video, use the command:
</p><div class="example">
<pre class="example">subtitles=sub.srt
</pre></div>
<p>which is equivalent to:
</p><div class="example">
<pre class="example">subtitles=filename=sub.srt
</pre></div>
<p>To render the default subtitles stream from file <samp>video.mkv</samp>, use:
</p><div class="example">
<pre class="example">subtitles=video.mkv
</pre></div>
<p>To render the second subtitles stream from that file, use:
</p><div class="example">
<pre class="example">subtitles=video.mkv:si=1
</pre></div>
<p>To make the subtitles stream from <samp>sub.srt</samp> appear in transparent green
<code>DejaVu Serif</code>, use:
</p><div class="example">
<pre class="example">subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
</pre></div>
<a name="super2xsai"></a>
<h3 class="section">37.113 super2xsai<span class="pull-right"><a class="anchor hidden-xs" href="#super2xsai" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-super2xsai" aria-hidden="true">TOC</a></span></h3>
<p>Scale the input by 2x and smooth using the Super2xSaI (Scale and
Interpolate) pixel art scaling algorithm.
</p>
<p>Useful for enlarging pixel art images without reducing sharpness.
</p>
<a name="swapuv"></a>
<h3 class="section">37.114 swapuv<span class="pull-right"><a class="anchor hidden-xs" href="#swapuv" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-swapuv" aria-hidden="true">TOC</a></span></h3>
<p>Swap U & V plane.
</p>
<a name="telecine"></a>
<h3 class="section">37.115 telecine<span class="pull-right"><a class="anchor hidden-xs" href="#telecine" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-telecine" aria-hidden="true">TOC</a></span></h3>
<p>Apply telecine process to the video.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>first_field</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>top, t</samp>’</dt>
<dd><p>top field first
</p></dd>
<dt>‘<samp>bottom, b</samp>’</dt>
<dd><p>bottom field first
The default value is <code>top</code>.
</p></dd>
</dl>
</dd>
<dt><samp>pattern</samp></dt>
<dd><p>A string of numbers representing the pulldown pattern you wish to apply.
The default value is <code>23</code>.
</p></dd>
</dl>
<div class="example">
<pre class="example">Some typical patterns:
NTSC output (30i):
27.5p: 32222
24p: 23 (classic)
24p: 2332 (preferred)
20p: 33
18p: 334
16p: 3444
PAL output (25i):
27.5p: 12222
24p: 222222222223 ("Euro pulldown")
16.67p: 33
16p: 33333334
</pre></div>
<a name="thumbnail"></a>
<h3 class="section">37.116 thumbnail<span class="pull-right"><a class="anchor hidden-xs" href="#thumbnail" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-thumbnail" aria-hidden="true">TOC</a></span></h3>
<p>Select the most representative frame in a given sequence of consecutive frames.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>Set the frames batch size to analyze; in a set of <var>n</var> frames, the filter
will pick one of them, and then handle the next batch of <var>n</var> frames until
the end. Default is <code>100</code>.
</p></dd>
</dl>
<p>Since the filter keeps track of the whole frames sequence, a bigger <var>n</var>
value will result in a higher memory usage, so a high value is not recommended.
</p>
<a name="Examples-99"></a>
<h4 class="subsection">37.116.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-99" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-99" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Extract one picture each 50 frames:
<div class="example">
<pre class="example">thumbnail=50
</pre></div>
</li><li> Complete example of a thumbnail creation with <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
</pre></div>
</li></ul>
<a name="tile"></a>
<h3 class="section">37.117 tile<span class="pull-right"><a class="anchor hidden-xs" href="#tile" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tile" aria-hidden="true">TOC</a></span></h3>
<p>Tile several successive frames together.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>layout</samp></dt>
<dd><p>Set the grid size (i.e. the number of lines and columns). For the syntax of
this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
</dd>
<dt><samp>nb_frames</samp></dt>
<dd><p>Set the maximum number of frames to render in the given area. It must be less
than or equal to <var>w</var>x<var>h</var>. The default value is <code>0</code>, meaning all
the area will be used.
</p>
</dd>
<dt><samp>margin</samp></dt>
<dd><p>Set the outer border margin in pixels.
</p>
</dd>
<dt><samp>padding</samp></dt>
<dd><p>Set the inner border thickness (i.e. the number of pixels between frames). For
more advanced padding options (such as having different values for the edges),
refer to the pad video filter.
</p>
</dd>
<dt><samp>color</samp></dt>
<dd><p>Specify the color of the unused area. For the syntax of this option, check the
"Color" section in the ffmpeg-utils manual. The default value of <var>color</var>
is "black".
</p></dd>
</dl>
<a name="Examples-100"></a>
<h4 class="subsection">37.117.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-100" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-100" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Produce 8x8 PNG tiles of all keyframes (<samp>-skip_frame nokey</samp>) in a movie:
<div class="example">
<pre class="example">ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
</pre></div>
<p>The <samp>-vsync 0</samp> is necessary to prevent <code>ffmpeg</code> from
duplicating each output frame to accommodate the originally detected frame
rate.
</p>
</li><li> Display <code>5</code> pictures in an area of <code>3x2</code> frames,
with <code>7</code> pixels between them, and <code>2</code> pixels of initial margin, using
mixed flat and named options:
<div class="example">
<pre class="example">tile=3x2:nb_frames=5:padding=7:margin=2
</pre></div>
</li></ul>
<a name="tinterlace"></a>
<h3 class="section">37.118 tinterlace<span class="pull-right"><a class="anchor hidden-xs" href="#tinterlace" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-tinterlace" aria-hidden="true">TOC</a></span></h3>
<p>Perform various types of temporal field interlacing.
</p>
<p>Frames are counted starting from 1, so the first input frame is
considered odd.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Specify the mode of the interlacing. This option can also be specified
as a value alone. See below for a list of values for this option.
</p>
<p>Available values are:
</p>
<dl compact="compact">
<dt>‘<samp>merge, 0</samp>’</dt>
<dd><p>Move odd frames into the upper field, even into the lower field,
generating a double height frame at half frame rate.
</p><div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 33333
22222 44444
11111 33333
22222 44444
11111 33333
22222 44444
11111 33333
22222 44444
</pre></div>
</dd>
<dt>‘<samp>drop_odd, 1</samp>’</dt>
<dd><p>Only output even frames, odd frames are dropped, generating a frame with
unchanged height at half frame rate.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
22222 44444
22222 44444
22222 44444
22222 44444
</pre></div>
</dd>
<dt>‘<samp>drop_even, 2</samp>’</dt>
<dd><p>Only output odd frames, even frames are dropped, generating a frame with
unchanged height at half frame rate.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 33333
11111 33333
11111 33333
11111 33333
</pre></div>
</dd>
<dt>‘<samp>pad, 3</samp>’</dt>
<dd><p>Expand each frame to full height, but pad alternate lines with black,
generating a frame with double height at the same input frame rate.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
</pre></div>
</dd>
<dt>‘<samp>interleave_top, 4</samp>’</dt>
<dd><p>Interleave the upper field from odd frames with the lower field from
even frames, generating a frame with unchanged height at half frame rate.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
Output:
11111 33333
22222 44444
11111 33333
22222 44444
</pre></div>
</dd>
<dt>‘<samp>interleave_bottom, 5</samp>’</dt>
<dd><p>Interleave the lower field from odd frames with the upper field from
even frames, generating a frame with unchanged height at half frame rate.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
Output:
22222 44444
11111 33333
22222 44444
11111 33333
</pre></div>
</dd>
<dt>‘<samp>interlacex2, 6</samp>’</dt>
<dd><p>Double frame rate with unchanged height. Frames are inserted each
containing the second temporal field from the previous input frame and
the first temporal field from the next input frame. This mode relies on
the top_field_first flag. Useful for interlaced video displays with no
field synchronisation.
</p>
<div class="example">
<pre class="example"> ------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 22222 22222 33333 33333 44444 44444
11111 11111 22222 22222 33333 33333 44444
11111 22222 22222 33333 33333 44444 44444
11111 11111 22222 22222 33333 33333 44444
</pre></div>
</dd>
</dl>
<p>Numeric values are deprecated but are accepted for backward
compatibility reasons.
</p>
<p>Default mode is <code>merge</code>.
</p>
</dd>
<dt><samp>flags</samp></dt>
<dd><p>Specify flags influencing the filter process.
</p>
<p>Available value for <var>flags</var> is:
</p>
<dl compact="compact">
<dt><samp>low_pass_filter, vlfp</samp></dt>
<dd><p>Enable vertical low-pass filtering in the filter.
Vertical low-pass filtering is required when creating an interlaced
destination from a progressive source which contains high-frequency
vertical detail. Filtering will reduce interlace ’twitter’ and Moire
patterning.
</p>
<p>Vertical low-pass filtering can only be enabled for <samp>mode</samp>
<var>interleave_top</var> and <var>interleave_bottom</var>.
</p>
</dd>
</dl>
</dd>
</dl>
<a name="transpose"></a>
<h3 class="section">37.119 transpose<span class="pull-right"><a class="anchor hidden-xs" href="#transpose" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-transpose" aria-hidden="true">TOC</a></span></h3>
<p>Transpose rows with columns in the input video and optionally flip it.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>dir</samp></dt>
<dd><p>Specify the transposition direction.
</p>
<p>Can assume the following values:
</p><dl compact="compact">
<dt>‘<samp>0, 4, cclock_flip</samp>’</dt>
<dd><p>Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
</p><div class="example">
<pre class="example">L.R L.l
. . -> . .
l.r R.r
</pre></div>
</dd>
<dt>‘<samp>1, 5, clock</samp>’</dt>
<dd><p>Rotate by 90 degrees clockwise, that is:
</p><div class="example">
<pre class="example">L.R l.L
. . -> . .
l.r r.R
</pre></div>
</dd>
<dt>‘<samp>2, 6, cclock</samp>’</dt>
<dd><p>Rotate by 90 degrees counterclockwise, that is:
</p><div class="example">
<pre class="example">L.R R.r
. . -> . .
l.r L.l
</pre></div>
</dd>
<dt>‘<samp>3, 7, clock_flip</samp>’</dt>
<dd><p>Rotate by 90 degrees clockwise and vertically flip, that is:
</p><div class="example">
<pre class="example">L.R r.R
. . -> . .
l.r l.L
</pre></div>
</dd>
</dl>
<p>For values between 4-7, the transposition is only done if the input
video geometry is portrait and not landscape. These values are
deprecated, the <code>passthrough</code> option should be used instead.
</p>
<p>Numerical values are deprecated, and should be dropped in favor of
symbolic constants.
</p>
</dd>
<dt><samp>passthrough</samp></dt>
<dd><p>Do not apply the transposition if the input geometry matches the one
specified by the specified value. It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>Always apply transposition.
</p></dd>
<dt>‘<samp>portrait</samp>’</dt>
<dd><p>Preserve portrait geometry (when <var>height</var> >= <var>width</var>).
</p></dd>
<dt>‘<samp>landscape</samp>’</dt>
<dd><p>Preserve landscape geometry (when <var>width</var> >= <var>height</var>).
</p></dd>
</dl>
<p>Default value is <code>none</code>.
</p></dd>
</dl>
<p>For example to rotate by 90 degrees clockwise and preserve portrait
layout:
</p><div class="example">
<pre class="example">transpose=dir=1:passthrough=portrait
</pre></div>
<p>The command above can also be specified as:
</p><div class="example">
<pre class="example">transpose=1:portrait
</pre></div>
<a name="trim"></a>
<h3 class="section">37.120 trim<span class="pull-right"><a class="anchor hidden-xs" href="#trim" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-trim" aria-hidden="true">TOC</a></span></h3>
<p>Trim the input so that the output contains one continuous subpart of the input.
</p>
<p>It accepts the following parameters:
</p><dl compact="compact">
<dt><samp>start</samp></dt>
<dd><p>Specify the time of the start of the kept section, i.e. the frame with the
timestamp <var>start</var> will be the first frame in the output.
</p>
</dd>
<dt><samp>end</samp></dt>
<dd><p>Specify the time of the first frame that will be dropped, i.e. the frame
immediately preceding the one with the timestamp <var>end</var> will be the last
frame in the output.
</p>
</dd>
<dt><samp>start_pts</samp></dt>
<dd><p>This is the same as <var>start</var>, except this option sets the start timestamp
in timebase units instead of seconds.
</p>
</dd>
<dt><samp>end_pts</samp></dt>
<dd><p>This is the same as <var>end</var>, except this option sets the end timestamp
in timebase units instead of seconds.
</p>
</dd>
<dt><samp>duration</samp></dt>
<dd><p>The maximum duration of the output in seconds.
</p>
</dd>
<dt><samp>start_frame</samp></dt>
<dd><p>The number of the first frame that should be passed to the output.
</p>
</dd>
<dt><samp>end_frame</samp></dt>
<dd><p>The number of the first frame that should be dropped.
</p></dd>
</dl>
<p><samp>start</samp>, <samp>end</samp>, and <samp>duration</samp> are expressed as time
duration specifications; see
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
</p>
<p>Note that the first two sets of the start/end options and the <samp>duration</samp>
option look at the frame timestamp, while the _frame variants simply count the
frames that pass through the filter. Also note that this filter does not modify
the timestamps. If you wish for the output timestamps to start at zero, insert a
setpts filter after the trim filter.
</p>
<p>If multiple start or end options are set, this filter tries to be greedy and
keep all the frames that match at least one of the specified constraints. To keep
only the part that matches all the constraints at once, chain multiple trim
filters.
</p>
<p>The defaults are such that all the input is kept. So it is possible to set e.g.
just the end values to keep everything before the specified time.
</p>
<p>Examples:
</p><ul>
<li> Drop everything except the second minute of input:
<div class="example">
<pre class="example">ffmpeg -i INPUT -vf trim=60:120
</pre></div>
</li><li> Keep only the first second:
<div class="example">
<pre class="example">ffmpeg -i INPUT -vf trim=duration=1
</pre></div>
</li></ul>
<a name="unsharp"></a><a name="unsharp-1"></a>
<h3 class="section">37.121 unsharp<span class="pull-right"><a class="anchor hidden-xs" href="#unsharp-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-unsharp-1" aria-hidden="true">TOC</a></span></h3>
<p>Sharpen or blur the input video.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>luma_msize_x, lx</samp></dt>
<dd><p>Set the luma matrix horizontal size. It must be an odd integer between
3 and 63. The default value is 5.
</p>
</dd>
<dt><samp>luma_msize_y, ly</samp></dt>
<dd><p>Set the luma matrix vertical size. It must be an odd integer between 3
and 63. The default value is 5.
</p>
</dd>
<dt><samp>luma_amount, la</samp></dt>
<dd><p>Set the luma effect strength. It must be a floating point number, reasonable
values lay between -1.5 and 1.5.
</p>
<p>Negative values will blur the input video, while positive values will
sharpen it, a value of zero will disable the effect.
</p>
<p>Default value is 1.0.
</p>
</dd>
<dt><samp>chroma_msize_x, cx</samp></dt>
<dd><p>Set the chroma matrix horizontal size. It must be an odd integer
between 3 and 63. The default value is 5.
</p>
</dd>
<dt><samp>chroma_msize_y, cy</samp></dt>
<dd><p>Set the chroma matrix vertical size. It must be an odd integer
between 3 and 63. The default value is 5.
</p>
</dd>
<dt><samp>chroma_amount, ca</samp></dt>
<dd><p>Set the chroma effect strength. It must be a floating point number, reasonable
values lay between -1.5 and 1.5.
</p>
<p>Negative values will blur the input video, while positive values will
sharpen it, a value of zero will disable the effect.
</p>
<p>Default value is 0.0.
</p>
</dd>
<dt><samp>opencl</samp></dt>
<dd><p>If set to 1, specify using OpenCL capabilities, only available if
FFmpeg was configured with <code>--enable-opencl</code>. Default value is 0.
</p>
</dd>
</dl>
<p>All parameters are optional and default to the equivalent of the
string ’5:5:1.0:5:5:0.0’.
</p>
<a name="Examples-101"></a>
<h4 class="subsection">37.121.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-101" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-101" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply strong luma sharpen effect:
<div class="example">
<pre class="example">unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
</pre></div>
</li><li> Apply a strong blur of both luma and chroma parameters:
<div class="example">
<pre class="example">unsharp=7:7:-2:7:7:-2
</pre></div>
</li></ul>
<a name="uspp"></a>
<h3 class="section">37.122 uspp<span class="pull-right"><a class="anchor hidden-xs" href="#uspp" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-uspp" aria-hidden="true">TOC</a></span></h3>
<p>Apply ultra slow/simple postprocessing filter that compresses and decompresses
the image at several (or - in the case of <samp>quality</samp> level <code>8</code> - all)
shifts and average the results.
</p>
<p>The way this differs from the behavior of spp is that uspp actually encodes &
decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
DCT similar to MJPEG.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>quality</samp></dt>
<dd><p>Set quality. This option defines the number of levels for averaging. It accepts
an integer in the range 0-8. If set to <code>0</code>, the filter will have no
effect. A value of <code>8</code> means the higher quality. For each increment of
that value the speed drops by a factor of approximately 2. Default value is
<code>3</code>.
</p>
</dd>
<dt><samp>qp</samp></dt>
<dd><p>Force a constant quantization parameter. If not set, the filter will use the QP
from the video stream (if available).
</p></dd>
</dl>
<a name="vectorscope"></a>
<h3 class="section">37.123 vectorscope<span class="pull-right"><a class="anchor hidden-xs" href="#vectorscope" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vectorscope" aria-hidden="true">TOC</a></span></h3>
<p>Display 2 color component values in the two dimensional graph (which is called
a vectorscope).
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode, m</samp></dt>
<dd><p>Set vectorscope mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>gray</samp>’</dt>
<dd><p>Gray values are displayed on graph, higher brightness means more pixels have
same component color value on location in graph. This is the default mode.
</p>
</dd>
<dt>‘<samp>color</samp>’</dt>
<dd><p>Gray values are displayed on graph. Surrounding pixels values which are not
present in video frame are drawn in gradient of 2 color components which are
set by option <code>x</code> and <code>y</code>.
</p>
</dd>
<dt>‘<samp>color2</samp>’</dt>
<dd><p>Actual color components values present in video frame are displayed on graph.
</p>
</dd>
<dt>‘<samp>color3</samp>’</dt>
<dd><p>Similar as color2 but higher frequency of same values <code>x</code> and <code>y</code>
on graph increases value of another color component, which is luminance by
default values of <code>x</code> and <code>y</code>.
</p>
</dd>
<dt>‘<samp>color4</samp>’</dt>
<dd><p>Actual colors present in video frame are displayed on graph. If two different
colors map to same position on graph then color with higher value of component
not present in graph is picked.
</p></dd>
</dl>
</dd>
<dt><samp>x</samp></dt>
<dd><p>Set which color component will be represented on X-axis. Default is <code>1</code>.
</p>
</dd>
<dt><samp>y</samp></dt>
<dd><p>Set which color component will be represented on Y-axis. Default is <code>2</code>.
</p>
</dd>
<dt><samp>intensity, i</samp></dt>
<dd><p>Set intensity, used by modes: gray, color and color3 for increasing brightness
of color component which represents frequency of (X, Y) location in graph.
</p>
</dd>
<dt><samp>envelope, e</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>No envelope, this is default.
</p>
</dd>
<dt>‘<samp>instant</samp>’</dt>
<dd><p>Instant envelope, even darkest single pixel will be clearly highlighted.
</p>
</dd>
<dt>‘<samp>peak</samp>’</dt>
<dd><p>Hold maximum and minimum values presented in graph over time. This way you
can still spot out of range values without constantly looking at vectorscope.
</p>
</dd>
<dt>‘<samp>peak+instant</samp>’</dt>
<dd><p>Peak and instant envelope combined together.
</p></dd>
</dl>
</dd>
</dl>
<a name="vidstabdetect"></a><a name="vidstabdetect-1"></a>
<h3 class="section">37.124 vidstabdetect<span class="pull-right"><a class="anchor hidden-xs" href="#vidstabdetect-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vidstabdetect-1" aria-hidden="true">TOC</a></span></h3>
<p>Analyze video stabilization/deshaking. Perform pass 1 of 2, see
<a href="#vidstabtransform">vidstabtransform</a> for pass 2.
</p>
<p>This filter generates a file with relative translation and rotation
transform information about subsequent frames, which is then used by
the <a href="#vidstabtransform">vidstabtransform</a> filter.
</p>
<p>To enable compilation of this filter you need to configure FFmpeg with
<code>--enable-libvidstab</code>.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>result</samp></dt>
<dd><p>Set the path to the file used to write the transforms information.
Default value is <samp>transforms.trf</samp>.
</p>
</dd>
<dt><samp>shakiness</samp></dt>
<dd><p>Set how shaky the video is and how quick the camera is. It accepts an
integer in the range 1-10, a value of 1 means little shakiness, a
value of 10 means strong shakiness. Default value is 5.
</p>
</dd>
<dt><samp>accuracy</samp></dt>
<dd><p>Set the accuracy of the detection process. It must be a value in the
range 1-15. A value of 1 means low accuracy, a value of 15 means high
accuracy. Default value is 15.
</p>
</dd>
<dt><samp>stepsize</samp></dt>
<dd><p>Set stepsize of the search process. The region around minimum is
scanned with 1 pixel resolution. Default value is 6.
</p>
</dd>
<dt><samp>mincontrast</samp></dt>
<dd><p>Set minimum contrast. Below this value a local measurement field is
discarded. Must be a floating point value in the range 0-1. Default
value is 0.3.
</p>
</dd>
<dt><samp>tripod</samp></dt>
<dd><p>Set reference frame number for tripod mode.
</p>
<p>If enabled, the motion of the frames is compared to a reference frame
in the filtered stream, identified by the specified number. The idea
is to compensate all movements in a more-or-less static scene and keep
the camera view absolutely still.
</p>
<p>If set to 0, it is disabled. The frames are counted starting from 1.
</p>
</dd>
<dt><samp>show</samp></dt>
<dd><p>Show fields and transforms in the resulting frames. It accepts an
integer in the range 0-2. Default value is 0, which disables any
visualization.
</p></dd>
</dl>
<a name="Examples-102"></a>
<h4 class="subsection">37.124.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-102" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-102" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use default values:
<div class="example">
<pre class="example">vidstabdetect
</pre></div>
</li><li> Analyze strongly shaky movie and put the results in file
<samp>mytransforms.trf</samp>:
<div class="example">
<pre class="example">vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
</pre></div>
</li><li> Visualize the result of internal transformations in the resulting
video:
<div class="example">
<pre class="example">vidstabdetect=show=1
</pre></div>
</li><li> Analyze a video with medium shakiness using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
</pre></div>
</li></ul>
<a name="vidstabtransform"></a><a name="vidstabtransform-1"></a>
<h3 class="section">37.125 vidstabtransform<span class="pull-right"><a class="anchor hidden-xs" href="#vidstabtransform-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vidstabtransform-1" aria-hidden="true">TOC</a></span></h3>
<p>Video stabilization/deshaking: pass 2 of 2,
see <a href="#vidstabdetect">vidstabdetect</a> for pass 1.
</p>
<p>Read a file with transform information for each frame and
apply/compensate them. Together with the <a href="#vidstabdetect">vidstabdetect</a>
filter this can be used to deshake videos. See also
<a href="http://public.hronopik.de/vid.stab">http://public.hronopik.de/vid.stab</a>. It is important to also use
the <a href="#unsharp">unsharp</a> filter, see below.
</p>
<p>To enable compilation of this filter you need to configure FFmpeg with
<code>--enable-libvidstab</code>.
</p>
<a name="Options-70"></a>
<h4 class="subsection">37.125.1 Options<span class="pull-right"><a class="anchor hidden-xs" href="#Options-70" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Options-70" aria-hidden="true">TOC</a></span></h4>
<dl compact="compact">
<dt><samp>input</samp></dt>
<dd><p>Set path to the file used to read the transforms. Default value is
<samp>transforms.trf</samp>.
</p>
</dd>
<dt><samp>smoothing</samp></dt>
<dd><p>Set the number of frames (value*2 + 1) used for lowpass filtering the
camera movements. Default value is 10.
</p>
<p>For example a number of 10 means that 21 frames are used (10 in the
past and 10 in the future) to smoothen the motion in the video. A
larger value leads to a smoother video, but limits the acceleration of
the camera (pan/tilt movements). 0 is a special case where a static
camera is simulated.
</p>
</dd>
<dt><samp>optalgo</samp></dt>
<dd><p>Set the camera path optimization algorithm.
</p>
<p>Accepted values are:
</p><dl compact="compact">
<dt>‘<samp>gauss</samp>’</dt>
<dd><p>gaussian kernel low-pass filter on camera motion (default)
</p></dd>
<dt>‘<samp>avg</samp>’</dt>
<dd><p>averaging on transformations
</p></dd>
</dl>
</dd>
<dt><samp>maxshift</samp></dt>
<dd><p>Set maximal number of pixels to translate frames. Default value is -1,
meaning no limit.
</p>
</dd>
<dt><samp>maxangle</samp></dt>
<dd><p>Set maximal angle in radians (degree*PI/180) to rotate frames. Default
value is -1, meaning no limit.
</p>
</dd>
<dt><samp>crop</samp></dt>
<dd><p>Specify how to deal with borders that may be visible due to movement
compensation.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>keep</samp>’</dt>
<dd><p>keep image information from previous frame (default)
</p></dd>
<dt>‘<samp>black</samp>’</dt>
<dd><p>fill the border black
</p></dd>
</dl>
</dd>
<dt><samp>invert</samp></dt>
<dd><p>Invert transforms if set to 1. Default value is 0.
</p>
</dd>
<dt><samp>relative</samp></dt>
<dd><p>Consider transforms as relative to previous frame if set to 1,
absolute if set to 0. Default value is 0.
</p>
</dd>
<dt><samp>zoom</samp></dt>
<dd><p>Set percentage to zoom. A positive value will result in a zoom-in
effect, a negative value in a zoom-out effect. Default value is 0 (no
zoom).
</p>
</dd>
<dt><samp>optzoom</samp></dt>
<dd><p>Set optimal zooming to avoid borders.
</p>
<p>Accepted values are:
</p><dl compact="compact">
<dt>‘<samp>0</samp>’</dt>
<dd><p>disabled
</p></dd>
<dt>‘<samp>1</samp>’</dt>
<dd><p>optimal static zoom value is determined (only very strong movements
will lead to visible borders) (default)
</p></dd>
<dt>‘<samp>2</samp>’</dt>
<dd><p>optimal adaptive zoom value is determined (no borders will be
visible), see <samp>zoomspeed</samp>
</p></dd>
</dl>
<p>Note that the value given at zoom is added to the one calculated here.
</p>
</dd>
<dt><samp>zoomspeed</samp></dt>
<dd><p>Set percent to zoom maximally each frame (enabled when
<samp>optzoom</samp> is set to 2). Range is from 0 to 5, default value is
0.25.
</p>
</dd>
<dt><samp>interpol</samp></dt>
<dd><p>Specify type of interpolation.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>no</samp>’</dt>
<dd><p>no interpolation
</p></dd>
<dt>‘<samp>linear</samp>’</dt>
<dd><p>linear only horizontal
</p></dd>
<dt>‘<samp>bilinear</samp>’</dt>
<dd><p>linear in both directions (default)
</p></dd>
<dt>‘<samp>bicubic</samp>’</dt>
<dd><p>cubic in both directions (slow)
</p></dd>
</dl>
</dd>
<dt><samp>tripod</samp></dt>
<dd><p>Enable virtual tripod mode if set to 1, which is equivalent to
<code>relative=0:smoothing=0</code>. Default value is 0.
</p>
<p>Use also <code>tripod</code> option of <a href="#vidstabdetect">vidstabdetect</a>.
</p>
</dd>
<dt><samp>debug</samp></dt>
<dd><p>Increase log verbosity if set to 1. Also the detected global motions
are written to the temporary file <samp>global_motions.trf</samp>. Default
value is 0.
</p></dd>
</dl>
<a name="Examples-103"></a>
<h4 class="subsection">37.125.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-103" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-103" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Use <code>ffmpeg</code> for a typical stabilization with default values:
<div class="example">
<pre class="example">ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
</pre></div>
<p>Note the use of the <a href="#unsharp">unsharp</a> filter which is always recommended.
</p>
</li><li> Zoom in a bit more and load transform data from a given file:
<div class="example">
<pre class="example">vidstabtransform=zoom=5:input="mytransforms.trf"
</pre></div>
</li><li> Smoothen the video even more:
<div class="example">
<pre class="example">vidstabtransform=smoothing=30
</pre></div>
</li></ul>
<a name="vflip"></a>
<h3 class="section">37.126 vflip<span class="pull-right"><a class="anchor hidden-xs" href="#vflip" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vflip" aria-hidden="true">TOC</a></span></h3>
<p>Flip the input video vertically.
</p>
<p>For example, to vertically flip a video with <code>ffmpeg</code>:
</p><div class="example">
<pre class="example">ffmpeg -i in.avi -vf "vflip" out.avi
</pre></div>
<a name="vignette"></a><a name="vignette-1"></a>
<h3 class="section">37.127 vignette<span class="pull-right"><a class="anchor hidden-xs" href="#vignette-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vignette-1" aria-hidden="true">TOC</a></span></h3>
<p>Make or reverse a natural vignetting effect.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>angle, a</samp></dt>
<dd><p>Set lens angle expression as a number of radians.
</p>
<p>The value is clipped in the <code>[0,PI/2]</code> range.
</p>
<p>Default value: <code>"PI/5"</code>
</p>
</dd>
<dt><samp>x0</samp></dt>
<dt><samp>y0</samp></dt>
<dd><p>Set center coordinates expressions. Respectively <code>"w/2"</code> and <code>"h/2"</code>
by default.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set forward/backward mode.
</p>
<p>Available modes are:
</p><dl compact="compact">
<dt>‘<samp>forward</samp>’</dt>
<dd><p>The larger the distance from the central point, the darker the image becomes.
</p>
</dd>
<dt>‘<samp>backward</samp>’</dt>
<dd><p>The larger the distance from the central point, the brighter the image becomes.
This can be used to reverse a vignette effect, though there is no automatic
detection to extract the lens <samp>angle</samp> and other settings (yet). It can
also be used to create a burning effect.
</p></dd>
</dl>
<p>Default value is ‘<samp>forward</samp>’.
</p>
</dd>
<dt><samp>eval</samp></dt>
<dd><p>Set evaluation mode for the expressions (<samp>angle</samp>, <samp>x0</samp>, <samp>y0</samp>).
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>init</samp>’</dt>
<dd><p>Evaluate expressions only once during the filter initialization.
</p>
</dd>
<dt>‘<samp>frame</samp>’</dt>
<dd><p>Evaluate expressions for each incoming frame. This is way slower than the
‘<samp>init</samp>’ mode since it requires all the scalers to be re-computed, but it
allows advanced dynamic expressions.
</p></dd>
</dl>
<p>Default value is ‘<samp>init</samp>’.
</p>
</dd>
<dt><samp>dither</samp></dt>
<dd><p>Set dithering to reduce the circular banding effects. Default is <code>1</code>
(enabled).
</p>
</dd>
<dt><samp>aspect</samp></dt>
<dd><p>Set vignette aspect. This setting allows one to adjust the shape of the vignette.
Setting this value to the SAR of the input will make a rectangular vignetting
following the dimensions of the video.
</p>
<p>Default is <code>1/1</code>.
</p></dd>
</dl>
<a name="Expressions"></a>
<h4 class="subsection">37.127.1 Expressions<span class="pull-right"><a class="anchor hidden-xs" href="#Expressions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Expressions" aria-hidden="true">TOC</a></span></h4>
<p>The <samp>alpha</samp>, <samp>x0</samp> and <samp>y0</samp> expressions can contain the
following parameters.
</p>
<dl compact="compact">
<dt><samp>w</samp></dt>
<dt><samp>h</samp></dt>
<dd><p>input width and height
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>the number of input frame, starting from 0
</p>
</dd>
<dt><samp>pts</samp></dt>
<dd><p>the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
<var>TB</var> units, NAN if undefined
</p>
</dd>
<dt><samp>r</samp></dt>
<dd><p>frame rate of the input video, NAN if the input frame rate is unknown
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in seconds, NAN if undefined
</p>
</dd>
<dt><samp>tb</samp></dt>
<dd><p>time base of the input video
</p></dd>
</dl>
<a name="Examples-104"></a>
<h4 class="subsection">37.127.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-104" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-104" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Apply simple strong vignetting effect:
<div class="example">
<pre class="example">vignette=PI/4
</pre></div>
</li><li> Make a flickering vignetting:
<div class="example">
<pre class="example">vignette='PI/4+random(1)*PI/50':eval=frame
</pre></div>
</li></ul>
<a name="vstack"></a>
<h3 class="section">37.128 vstack<span class="pull-right"><a class="anchor hidden-xs" href="#vstack" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-vstack" aria-hidden="true">TOC</a></span></h3>
<p>Stack input videos vertically.
</p>
<p>All streams must be of same pixel format and of same width.
</p>
<p>Note that this filter is faster than using <a href="#overlay">overlay</a> and <a href="#pad">pad</a> filter
to create same output.
</p>
<p>The filter accept the following option:
</p>
<dl compact="compact">
<dt><samp>nb_inputs</samp></dt>
<dd><p>Set number of input streams. Default is 2.
</p></dd>
</dl>
<a name="w3fdif"></a>
<h3 class="section">37.129 w3fdif<span class="pull-right"><a class="anchor hidden-xs" href="#w3fdif" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-w3fdif" aria-hidden="true">TOC</a></span></h3>
<p>Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
Deinterlacing Filter").
</p>
<p>Based on the process described by Martin Weston for BBC R&D, and
implemented based on the de-interlace algorithm written by Jim
Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
uses filter coefficients calculated by BBC R&D.
</p>
<p>There are two sets of filter coefficients, so called "simple":
and "complex". Which set of filter coefficients is used can
be set by passing an optional parameter:
</p>
<dl compact="compact">
<dt><samp>filter</samp></dt>
<dd><p>Set the interlacing filter coefficients. Accepts one of the following values:
</p>
<dl compact="compact">
<dt>‘<samp>simple</samp>’</dt>
<dd><p>Simple filter coefficient set.
</p></dd>
<dt>‘<samp>complex</samp>’</dt>
<dd><p>More-complex filter coefficient set.
</p></dd>
</dl>
<p>Default value is ‘<samp>complex</samp>’.
</p>
</dd>
<dt><samp>deint</samp></dt>
<dd><p>Specify which frames to deinterlace. Accept one of the following values:
</p>
<dl compact="compact">
<dt>‘<samp>all</samp>’</dt>
<dd><p>Deinterlace all frames,
</p></dd>
<dt>‘<samp>interlaced</samp>’</dt>
<dd><p>Only deinterlace frames marked as interlaced.
</p></dd>
</dl>
<p>Default value is ‘<samp>all</samp>’.
</p></dd>
</dl>
<a name="waveform"></a>
<h3 class="section">37.130 waveform<span class="pull-right"><a class="anchor hidden-xs" href="#waveform" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-waveform" aria-hidden="true">TOC</a></span></h3>
<p>Video waveform monitor.
</p>
<p>The waveform monitor plots color component intensity. By default luminance
only. Each column of the waveform corresponds to a column of pixels in the
source video.
</p>
<p>It accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode, m</samp></dt>
<dd><p>Can be either <code>row</code>, or <code>column</code>. Default is <code>column</code>.
In row mode, the graph on the left side represents color component value 0 and
the right side represents value = 255. In column mode, the top side represents
color component value = 0 and bottom side represents value = 255.
</p>
</dd>
<dt><samp>intensity, i</samp></dt>
<dd><p>Set intensity. Smaller values are useful to find out how many values of the same
luminance are distributed across input rows/columns.
Default value is <code>0.04</code>. Allowed range is [0, 1].
</p>
</dd>
<dt><samp>mirror, r</samp></dt>
<dd><p>Set mirroring mode. <code>0</code> means unmirrored, <code>1</code> means mirrored.
In mirrored mode, higher values will be represented on the left
side for <code>row</code> mode and at the top for <code>column</code> mode. Default is
<code>1</code> (mirrored).
</p>
</dd>
<dt><samp>display, d</samp></dt>
<dd><p>Set display mode.
It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>overlay</samp>’</dt>
<dd><p>Presents information identical to that in the <code>parade</code>, except
that the graphs representing color components are superimposed directly
over one another.
</p>
<p>This display mode makes it easier to spot relative differences or similarities
in overlapping areas of the color components that are supposed to be identical,
such as neutral whites, grays, or blacks.
</p>
</dd>
<dt>‘<samp>parade</samp>’</dt>
<dd><p>Display separate graph for the color components side by side in
<code>row</code> mode or one below the other in <code>column</code> mode.
</p>
<p>Using this display mode makes it easy to spot color casts in the highlights
and shadows of an image, by comparing the contours of the top and the bottom
graphs of each waveform. Since whites, grays, and blacks are characterized
by exactly equal amounts of red, green, and blue, neutral areas of the picture
should display three waveforms of roughly equal width/height. If not, the
correction is easy to perform by making level adjustments the three waveforms.
</p></dd>
</dl>
<p>Default is <code>parade</code>.
</p>
</dd>
<dt><samp>components, c</samp></dt>
<dd><p>Set which color components to display. Default is 1, which means only luminance
or red color component if input is in RGB colorspace. If is set for example to
7 it will display all 3 (if) available color components.
</p>
</dd>
<dt><samp>envelope, e</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>No envelope, this is default.
</p>
</dd>
<dt>‘<samp>instant</samp>’</dt>
<dd><p>Instant envelope, minimum and maximum values presented in graph will be easily
visible even with small <code>step</code> value.
</p>
</dd>
<dt>‘<samp>peak</samp>’</dt>
<dd><p>Hold minimum and maximum values presented in graph across time. This way you
can still spot out of range values without constantly looking at waveforms.
</p>
</dd>
<dt>‘<samp>peak+instant</samp>’</dt>
<dd><p>Peak and instant envelope combined together.
</p></dd>
</dl>
</dd>
<dt><samp>filter, f</samp></dt>
<dd><dl compact="compact">
<dt>‘<samp>lowpass</samp>’</dt>
<dd><p>No filtering, this is default.
</p>
</dd>
<dt>‘<samp>flat</samp>’</dt>
<dd><p>Luma and chroma combined together.
</p>
</dd>
<dt>‘<samp>aflat</samp>’</dt>
<dd><p>Similar as above, but shows difference between blue and red chroma.
</p>
</dd>
<dt>‘<samp>chroma</samp>’</dt>
<dd><p>Displays only chroma.
</p>
</dd>
<dt>‘<samp>achroma</samp>’</dt>
<dd><p>Similar as above, but shows difference between blue and red chroma.
</p>
</dd>
<dt>‘<samp>color</samp>’</dt>
<dd><p>Displays actual color value on waveform.
</p></dd>
</dl>
</dd>
</dl>
<a name="xbr"></a>
<h3 class="section">37.131 xbr<span class="pull-right"><a class="anchor hidden-xs" href="#xbr" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-xbr" aria-hidden="true">TOC</a></span></h3>
<p>Apply the xBR high-quality magnification filter which is designed for pixel
art. It follows a set of edge-detection rules, see
<a href="http://www.libretro.com/forums/viewtopic.php?f=6&t=134">http://www.libretro.com/forums/viewtopic.php?f=6&t=134</a>.
</p>
<p>It accepts the following option:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>Set the scaling dimension: <code>2</code> for <code>2xBR</code>, <code>3</code> for
<code>3xBR</code> and <code>4</code> for <code>4xBR</code>.
Default is <code>3</code>.
</p></dd>
</dl>
<a name="yadif"></a><a name="yadif-1"></a>
<h3 class="section">37.132 yadif<span class="pull-right"><a class="anchor hidden-xs" href="#yadif-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-yadif-1" aria-hidden="true">TOC</a></span></h3>
<p>Deinterlace the input video ("yadif" means "yet another deinterlacing
filter").
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>The interlacing mode to adopt. It accepts one of the following values:
</p>
<dl compact="compact">
<dt><samp>0, send_frame</samp></dt>
<dd><p>Output one frame for each frame.
</p></dd>
<dt><samp>1, send_field</samp></dt>
<dd><p>Output one frame for each field.
</p></dd>
<dt><samp>2, send_frame_nospatial</samp></dt>
<dd><p>Like <code>send_frame</code>, but it skips the spatial interlacing check.
</p></dd>
<dt><samp>3, send_field_nospatial</samp></dt>
<dd><p>Like <code>send_field</code>, but it skips the spatial interlacing check.
</p></dd>
</dl>
<p>The default value is <code>send_frame</code>.
</p>
</dd>
<dt><samp>parity</samp></dt>
<dd><p>The picture field parity assumed for the input interlaced video. It accepts one
of the following values:
</p>
<dl compact="compact">
<dt><samp>0, tff</samp></dt>
<dd><p>Assume the top field is first.
</p></dd>
<dt><samp>1, bff</samp></dt>
<dd><p>Assume the bottom field is first.
</p></dd>
<dt><samp>-1, auto</samp></dt>
<dd><p>Enable automatic detection of field parity.
</p></dd>
</dl>
<p>The default value is <code>auto</code>.
If the interlacing is unknown or the decoder does not export this information,
top field first will be assumed.
</p>
</dd>
<dt><samp>deint</samp></dt>
<dd><p>Specify which frames to deinterlace. Accept one of the following
values:
</p>
<dl compact="compact">
<dt><samp>0, all</samp></dt>
<dd><p>Deinterlace all frames.
</p></dd>
<dt><samp>1, interlaced</samp></dt>
<dd><p>Only deinterlace frames marked as interlaced.
</p></dd>
</dl>
<p>The default value is <code>all</code>.
</p></dd>
</dl>
<a name="zoompan"></a>
<h3 class="section">37.133 zoompan<span class="pull-right"><a class="anchor hidden-xs" href="#zoompan" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-zoompan" aria-hidden="true">TOC</a></span></h3>
<p>Apply Zoom & Pan effect.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>zoom, z</samp></dt>
<dd><p>Set the zoom expression. Default is 1.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Set the x and y expression. Default is 0.
</p>
</dd>
<dt><samp>d</samp></dt>
<dd><p>Set the duration expression in number of frames.
This sets for how many number of frames effect will last for
single input image.
</p>
</dd>
<dt><samp>s</samp></dt>
<dd><p>Set the output image size, default is ’hd720’.
</p></dd>
</dl>
<p>Each expression can contain the following constants:
</p>
<dl compact="compact">
<dt><samp>in_w, iw</samp></dt>
<dd><p>Input width.
</p>
</dd>
<dt><samp>in_h, ih</samp></dt>
<dd><p>Input height.
</p>
</dd>
<dt><samp>out_w, ow</samp></dt>
<dd><p>Output width.
</p>
</dd>
<dt><samp>out_h, oh</samp></dt>
<dd><p>Output height.
</p>
</dd>
<dt><samp>in</samp></dt>
<dd><p>Input frame count.
</p>
</dd>
<dt><samp>on</samp></dt>
<dd><p>Output frame count.
</p>
</dd>
<dt><samp>x</samp></dt>
<dt><samp>y</samp></dt>
<dd><p>Last calculated ’x’ and ’y’ position from ’x’ and ’y’ expression
for current input frame.
</p>
</dd>
<dt><samp>px</samp></dt>
<dt><samp>py</samp></dt>
<dd><p>’x’ and ’y’ of last output frame of previous input frame or 0 when there was
not yet such frame (first input frame).
</p>
</dd>
<dt><samp>zoom</samp></dt>
<dd><p>Last calculated zoom from ’z’ expression for current input frame.
</p>
</dd>
<dt><samp>pzoom</samp></dt>
<dd><p>Last calculated zoom of last output frame of previous input frame.
</p>
</dd>
<dt><samp>duration</samp></dt>
<dd><p>Number of output frames for current input frame. Calculated from ’d’ expression
for each input frame.
</p>
</dd>
<dt><samp>pduration</samp></dt>
<dd><p>number of output frames created for previous input frame
</p>
</dd>
<dt><samp>a</samp></dt>
<dd><p>Rational number: input width / input height
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>sample aspect ratio
</p>
</dd>
<dt><samp>dar</samp></dt>
<dd><p>display aspect ratio
</p>
</dd>
</dl>
<a name="Examples-105"></a>
<h4 class="subsection">37.133.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-105" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-105" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
<div class="example">
<pre class="example">zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360
</pre></div>
</li><li> Zoom-in up to 1.5 and pan always at center of picture:
<div class="example">
<pre class="example">zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
</pre></div>
</li></ul>
<a name="Video-Sources"></a>
<h2 class="chapter">38 Video Sources<span class="pull-right"><a class="anchor hidden-xs" href="#Video-Sources" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-Sources" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available video sources.
</p>
<a name="buffer"></a>
<h3 class="section">38.1 buffer<span class="pull-right"><a class="anchor hidden-xs" href="#buffer" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-buffer" aria-hidden="true">TOC</a></span></h3>
<p>Buffer video frames, and make them available to the filter chain.
</p>
<p>This source is mainly intended for a programmatic use, in particular
through the interface defined in <samp>libavfilter/vsrc_buffer.h</samp>.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>video_size</samp></dt>
<dd><p>Specify the size (width and height) of the buffered video frames. For the
syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
</dd>
<dt><samp>width</samp></dt>
<dd><p>The input video width.
</p>
</dd>
<dt><samp>height</samp></dt>
<dd><p>The input video height.
</p>
</dd>
<dt><samp>pix_fmt</samp></dt>
<dd><p>A string representing the pixel format of the buffered video frames.
It may be a number corresponding to a pixel format, or a pixel format
name.
</p>
</dd>
<dt><samp>time_base</samp></dt>
<dd><p>Specify the timebase assumed by the timestamps of the buffered frames.
</p>
</dd>
<dt><samp>frame_rate</samp></dt>
<dd><p>Specify the frame rate expected for the video stream.
</p>
</dd>
<dt><samp>pixel_aspect, sar</samp></dt>
<dd><p>The sample (pixel) aspect ratio of the input video.
</p>
</dd>
<dt><samp>sws_param</samp></dt>
<dd><p>Specify the optional parameters to be used for the scale filter which
is automatically inserted when an input change is detected in the
input size or format.
</p></dd>
</dl>
<p>For example:
</p><div class="example">
<pre class="example">buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
</pre></div>
<p>will instruct the source to accept video frames with size 320x240 and
with format "yuv410p", assuming 1/24 as the timestamps timebase and
square pixels (1:1 sample aspect ratio).
Since the pixel format with name "yuv410p" corresponds to the number 6
(check the enum AVPixelFormat definition in <samp>libavutil/pixfmt.h</samp>),
this example corresponds to:
</p><div class="example">
<pre class="example">buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
</pre></div>
<p>Alternatively, the options can be specified as a flat string, but this
syntax is deprecated:
</p>
<p><var>width</var>:<var>height</var>:<var>pix_fmt</var>:<var>time_base.num</var>:<var>time_base.den</var>:<var>pixel_aspect.num</var>:<var>pixel_aspect.den</var>[:<var>sws_param</var>]
</p>
<a name="cellauto"></a>
<h3 class="section">38.2 cellauto<span class="pull-right"><a class="anchor hidden-xs" href="#cellauto" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-cellauto" aria-hidden="true">TOC</a></span></h3>
<p>Create a pattern generated by an elementary cellular automaton.
</p>
<p>The initial state of the cellular automaton can be defined through the
<samp>filename</samp>, and <samp>pattern</samp> options. If such options are
not specified an initial state is created randomly.
</p>
<p>At each new frame a new row in the video is filled with the result of
the cellular automaton next generation. The behavior when the whole
frame is filled is defined by the <samp>scroll</samp> option.
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>filename, f</samp></dt>
<dd><p>Read the initial cellular automaton state, i.e. the starting row, from
the specified file.
In the file, each non-whitespace character is considered an alive
cell, a newline will terminate the row, and further characters in the
file will be ignored.
</p>
</dd>
<dt><samp>pattern, p</samp></dt>
<dd><p>Read the initial cellular automaton state, i.e. the starting row, from
the specified string.
</p>
<p>Each non-whitespace character in the string is considered an alive
cell, a newline will terminate the row, and further characters in the
string will be ignored.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Set the video rate, that is the number of frames generated per second.
Default is 25.
</p>
</dd>
<dt><samp>random_fill_ratio, ratio</samp></dt>
<dd><p>Set the random fill ratio for the initial cellular automaton row. It
is a floating point number value ranging from 0 to 1, defaults to
1/PHI.
</p>
<p>This option is ignored when a file or a pattern is specified.
</p>
</dd>
<dt><samp>random_seed, seed</samp></dt>
<dd><p>Set the seed for filling randomly the initial row, must be an integer
included between 0 and UINT32_MAX. If not specified, or if explicitly
set to -1, the filter will try to use a good random seed on a best
effort basis.
</p>
</dd>
<dt><samp>rule</samp></dt>
<dd><p>Set the cellular automaton rule, it is a number ranging from 0 to 255.
Default value is 110.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set the size of the output video. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
<p>If <samp>filename</samp> or <samp>pattern</samp> is specified, the size is set
by default to the width of the specified initial state row, and the
height is set to <var>width</var> * PHI.
</p>
<p>If <samp>size</samp> is set, it must contain the width of the specified
pattern string, and the specified pattern will be centered in the
larger row.
</p>
<p>If a filename or a pattern string is not specified, the size value
defaults to "320x518" (used for a randomly generated initial state).
</p>
</dd>
<dt><samp>scroll</samp></dt>
<dd><p>If set to 1, scroll the output upward when all the rows in the output
have been already filled. If set to 0, the new generated row will be
written over the top row just after the bottom row is filled.
Defaults to 1.
</p>
</dd>
<dt><samp>start_full, full</samp></dt>
<dd><p>If set to 1, completely fill the output with generated rows before
outputting the first frame.
This is the default behavior, for disabling set the value to 0.
</p>
</dd>
<dt><samp>stitch</samp></dt>
<dd><p>If set to 1, stitch the left and right row edges together.
This is the default behavior, for disabling set the value to 0.
</p></dd>
</dl>
<a name="Examples-106"></a>
<h4 class="subsection">38.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-106" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-106" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Read the initial state from <samp>pattern</samp>, and specify an output of
size 200x400.
<div class="example">
<pre class="example">cellauto=f=pattern:s=200x400
</pre></div>
</li><li> Generate a random initial row with a width of 200 cells, with a fill
ratio of 2/3:
<div class="example">
<pre class="example">cellauto=ratio=2/3:s=200x200
</pre></div>
</li><li> Create a pattern generated by rule 18 starting by a single alive cell
centered on an initial row with width 100:
<div class="example">
<pre class="example">cellauto=p=@:s=100x400:full=0:rule=18
</pre></div>
</li><li> Specify a more elaborated initial pattern:
<div class="example">
<pre class="example">cellauto=p='@@ @ @@':s=100x400:full=0:rule=18
</pre></div>
</li></ul>
<a name="mandelbrot"></a>
<h3 class="section">38.3 mandelbrot<span class="pull-right"><a class="anchor hidden-xs" href="#mandelbrot" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mandelbrot" aria-hidden="true">TOC</a></span></h3>
<p>Generate a Mandelbrot set fractal, and progressively zoom towards the
point specified with <var>start_x</var> and <var>start_y</var>.
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>end_pts</samp></dt>
<dd><p>Set the terminal pts value. Default value is 400.
</p>
</dd>
<dt><samp>end_scale</samp></dt>
<dd><p>Set the terminal scale value.
Must be a floating point value. Default value is 0.3.
</p>
</dd>
<dt><samp>inner</samp></dt>
<dd><p>Set the inner coloring mode, that is the algorithm used to draw the
Mandelbrot fractal internal region.
</p>
<p>It shall assume one of the following values:
</p><dl compact="compact">
<dt><samp>black</samp></dt>
<dd><p>Set black mode.
</p></dd>
<dt><samp>convergence</samp></dt>
<dd><p>Show time until convergence.
</p></dd>
<dt><samp>mincol</samp></dt>
<dd><p>Set color based on point closest to the origin of the iterations.
</p></dd>
<dt><samp>period</samp></dt>
<dd><p>Set period mode.
</p></dd>
</dl>
<p>Default value is <var>mincol</var>.
</p>
</dd>
<dt><samp>bailout</samp></dt>
<dd><p>Set the bailout value. Default value is 10.0.
</p>
</dd>
<dt><samp>maxiter</samp></dt>
<dd><p>Set the maximum of iterations performed by the rendering
algorithm. Default value is 7189.
</p>
</dd>
<dt><samp>outer</samp></dt>
<dd><p>Set outer coloring mode.
It shall assume one of following values:
</p><dl compact="compact">
<dt><samp>iteration_count</samp></dt>
<dd><p>Set iteration cound mode.
</p></dd>
<dt><samp>normalized_iteration_count</samp></dt>
<dd><p>set normalized iteration count mode.
</p></dd>
</dl>
<p>Default value is <var>normalized_iteration_count</var>.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Set frame rate, expressed as number of frames per second. Default
value is "25".
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set frame size. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "640x480".
</p>
</dd>
<dt><samp>start_scale</samp></dt>
<dd><p>Set the initial scale value. Default value is 3.0.
</p>
</dd>
<dt><samp>start_x</samp></dt>
<dd><p>Set the initial x position. Must be a floating point value between
-100 and 100. Default value is -0.743643887037158704752191506114774.
</p>
</dd>
<dt><samp>start_y</samp></dt>
<dd><p>Set the initial y position. Must be a floating point value between
-100 and 100. Default value is -0.131825904205311970493132056385139.
</p></dd>
</dl>
<a name="mptestsrc"></a>
<h3 class="section">38.4 mptestsrc<span class="pull-right"><a class="anchor hidden-xs" href="#mptestsrc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-mptestsrc" aria-hidden="true">TOC</a></span></h3>
<p>Generate various test patterns, as generated by the MPlayer test filter.
</p>
<p>The size of the generated video is fixed, and is 256x256.
This source is useful in particular for testing encoding features.
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rate, r</samp></dt>
<dd><p>Specify the frame rate of the sourced video, as the number of frames
generated per second. It has to be a string in the format
<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a floating point
number or a valid video frame rate abbreviation. The default value is
"25".
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Set the duration of the sourced video. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
</p>
<p>If not specified, or the expressed duration is negative, the video is
supposed to be generated forever.
</p>
</dd>
<dt><samp>test, t</samp></dt>
<dd>
<p>Set the number or the name of the test to perform. Supported tests are:
</p><dl compact="compact">
<dt><samp>dc_luma</samp></dt>
<dt><samp>dc_chroma</samp></dt>
<dt><samp>freq_luma</samp></dt>
<dt><samp>freq_chroma</samp></dt>
<dt><samp>amp_luma</samp></dt>
<dt><samp>amp_chroma</samp></dt>
<dt><samp>cbp</samp></dt>
<dt><samp>mv</samp></dt>
<dt><samp>ring1</samp></dt>
<dt><samp>ring2</samp></dt>
<dt><samp>all</samp></dt>
</dl>
<p>Default value is "all", which will cycle through the list of all tests.
</p></dd>
</dl>
<p>Some examples:
</p><div class="example">
<pre class="example">mptestsrc=t=dc_luma
</pre></div>
<p>will generate a "dc_luma" test pattern.
</p>
<a name="frei0r_005fsrc"></a>
<h3 class="section">38.5 frei0r_src<span class="pull-right"><a class="anchor hidden-xs" href="#frei0r_005fsrc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-frei0r_005fsrc" aria-hidden="true">TOC</a></span></h3>
<p>Provide a frei0r source.
</p>
<p>To enable compilation of this filter you need to install the frei0r
header and configure FFmpeg with <code>--enable-frei0r</code>.
</p>
<p>This source accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>size</samp></dt>
<dd><p>The size of the video to generate. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
</dd>
<dt><samp>framerate</samp></dt>
<dd><p>The framerate of the generated video. It may be a string of the form
<var>num</var>/<var>den</var> or a frame rate abbreviation.
</p>
</dd>
<dt><samp>filter_name</samp></dt>
<dd><p>The name to the frei0r source to load. For more information regarding frei0r and
how to set the parameters, read the <a href="#frei0r">frei0r</a> section in the video filters
documentation.
</p>
</dd>
<dt><samp>filter_params</samp></dt>
<dd><p>A ’|’-separated list of parameters to pass to the frei0r source.
</p>
</dd>
</dl>
<p>For example, to generate a frei0r partik0l source with size 200x200
and frame rate 10 which is overlaid on the overlay filter main input:
</p><div class="example">
<pre class="example">frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
</pre></div>
<a name="life"></a>
<h3 class="section">38.6 life<span class="pull-right"><a class="anchor hidden-xs" href="#life" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-life" aria-hidden="true">TOC</a></span></h3>
<p>Generate a life pattern.
</p>
<p>This source is based on a generalization of John Conway’s life game.
</p>
<p>The sourced input represents a life grid, each pixel represents a cell
which can be in one of two possible states, alive or dead. Every cell
interacts with its eight neighbours, which are the cells that are
horizontally, vertically, or diagonally adjacent.
</p>
<p>At each interaction the grid evolves according to the adopted rule,
which specifies the number of neighbor alive cells which will make a
cell stay alive or born. The <samp>rule</samp> option allows one to specify
the rule to adopt.
</p>
<p>This source accepts the following options:
</p>
<dl compact="compact">
<dt><samp>filename, f</samp></dt>
<dd><p>Set the file from which to read the initial grid state. In the file,
each non-whitespace character is considered an alive cell, and newline
is used to delimit the end of each row.
</p>
<p>If this option is not specified, the initial grid is generated
randomly.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Set the video rate, that is the number of frames generated per second.
Default is 25.
</p>
</dd>
<dt><samp>random_fill_ratio, ratio</samp></dt>
<dd><p>Set the random fill ratio for the initial random grid. It is a
floating point number value ranging from 0 to 1, defaults to 1/PHI.
It is ignored when a file is specified.
</p>
</dd>
<dt><samp>random_seed, seed</samp></dt>
<dd><p>Set the seed for filling the initial random grid, must be an integer
included between 0 and UINT32_MAX. If not specified, or if explicitly
set to -1, the filter will try to use a good random seed on a best
effort basis.
</p>
</dd>
<dt><samp>rule</samp></dt>
<dd><p>Set the life rule.
</p>
<p>A rule can be specified with a code of the kind "S<var>NS</var>/B<var>NB</var>",
where <var>NS</var> and <var>NB</var> are sequences of numbers in the range 0-8,
<var>NS</var> specifies the number of alive neighbor cells which make a
live cell stay alive, and <var>NB</var> the number of alive neighbor cells
which make a dead cell to become alive (i.e. to "born").
"s" and "b" can be used in place of "S" and "B", respectively.
</p>
<p>Alternatively a rule can be specified by an 18-bits integer. The 9
high order bits are used to encode the next cell state if it is alive
for each number of neighbor alive cells, the low order bits specify
the rule for "borning" new cells. Higher order bits encode for an
higher number of neighbor cells.
For example the number 6153 = <code>(12<<9)+9</code> specifies a stay alive
rule of 12 and a born rule of 9, which corresponds to "S23/B03".
</p>
<p>Default value is "S23/B3", which is the original Conway’s game of life
rule, and will keep a cell alive if it has 2 or 3 neighbor alive
cells, and will born a new cell if there are three alive cells around
a dead cell.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set the size of the output video. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
</p>
<p>If <samp>filename</samp> is specified, the size is set by default to the
same size of the input file. If <samp>size</samp> is set, it must contain
the size specified in the input file, and the initial grid defined in
that file is centered in the larger resulting area.
</p>
<p>If a filename is not specified, the size value defaults to "320x240"
(used for a randomly generated initial grid).
</p>
</dd>
<dt><samp>stitch</samp></dt>
<dd><p>If set to 1, stitch the left and right grid edges together, and the
top and bottom edges also. Defaults to 1.
</p>
</dd>
<dt><samp>mold</samp></dt>
<dd><p>Set cell mold speed. If set, a dead cell will go from <samp>death_color</samp> to
<samp>mold_color</samp> with a step of <samp>mold</samp>. <samp>mold</samp> can have a
value from 0 to 255.
</p>
</dd>
<dt><samp>life_color</samp></dt>
<dd><p>Set the color of living (or new born) cells.
</p>
</dd>
<dt><samp>death_color</samp></dt>
<dd><p>Set the color of dead cells. If <samp>mold</samp> is set, this is the first color
used to represent a dead cell.
</p>
</dd>
<dt><samp>mold_color</samp></dt>
<dd><p>Set mold color, for definitely dead and moldy cells.
</p>
<p>For the syntax of these 3 color options, check the "Color" section in the
ffmpeg-utils manual.
</p></dd>
</dl>
<a name="Examples-107"></a>
<h4 class="subsection">38.6.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-107" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-107" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Read a grid from <samp>pattern</samp>, and center it on a grid of size
300x300 pixels:
<div class="example">
<pre class="example">life=f=pattern:s=300x300
</pre></div>
</li><li> Generate a random grid of size 200x200, with a fill ratio of 2/3:
<div class="example">
<pre class="example">life=ratio=2/3:s=200x200
</pre></div>
</li><li> Specify a custom rule for evolving a randomly generated grid:
<div class="example">
<pre class="example">life=rule=S14/B34
</pre></div>
</li><li> Full example with slow death effect (mold) using <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
</pre></div>
</li></ul>
<a name="allrgb"></a><a name="allyuv"></a><a name="color"></a><a name="haldclutsrc"></a><a name="nullsrc"></a><a name="rgbtestsrc"></a><a name="smptebars"></a><a name="smptehdbars"></a><a name="testsrc"></a><a name="allrgb_002c-allyuv_002c-color_002c-haldclutsrc_002c-nullsrc_002c-rgbtestsrc_002c-smptebars_002c-smptehdbars_002c-testsrc"></a>
<h3 class="section">38.7 allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc<span class="pull-right"><a class="anchor hidden-xs" href="#allrgb_002c-allyuv_002c-color_002c-haldclutsrc_002c-nullsrc_002c-rgbtestsrc_002c-smptebars_002c-smptehdbars_002c-testsrc" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-allrgb_002c-allyuv_002c-color_002c-haldclutsrc_002c-nullsrc_002c-rgbtestsrc_002c-smptebars_002c-smptehdbars_002c-testsrc" aria-hidden="true">TOC</a></span></h3>
<p>The <code>allrgb</code> source returns frames of size 4096x4096 of all rgb colors.
</p>
<p>The <code>allyuv</code> source returns frames of size 4096x4096 of all yuv colors.
</p>
<p>The <code>color</code> source provides an uniformly colored input.
</p>
<p>The <code>haldclutsrc</code> source provides an identity Hald CLUT. See also
<a href="#haldclut">haldclut</a> filter.
</p>
<p>The <code>nullsrc</code> source returns unprocessed video frames. It is
mainly useful to be employed in analysis / debugging tools, or as the
source for filters which ignore the input data.
</p>
<p>The <code>rgbtestsrc</code> source generates an RGB test pattern useful for
detecting RGB vs BGR issues. You should see a red, green and blue
stripe from top to bottom.
</p>
<p>The <code>smptebars</code> source generates a color bars pattern, based on
the SMPTE Engineering Guideline EG 1-1990.
</p>
<p>The <code>smptehdbars</code> source generates a color bars pattern, based on
the SMPTE RP 219-2002.
</p>
<p>The <code>testsrc</code> source generates a test video pattern, showing a
color pattern, a scrolling gradient and a timestamp. This is mainly
intended for testing purposes.
</p>
<p>The sources accept the following parameters:
</p>
<dl compact="compact">
<dt><samp>color, c</samp></dt>
<dd><p>Specify the color of the source, only available in the <code>color</code>
source. For the syntax of this option, check the "Color" section in the
ffmpeg-utils manual.
</p>
</dd>
<dt><samp>level</samp></dt>
<dd><p>Specify the level of the Hald CLUT, only available in the <code>haldclutsrc</code>
source. A level of <code>N</code> generates a picture of <code>N*N*N</code> by <code>N*N*N</code>
pixels to be used as identity matrix for 3D lookup tables. Each component is
coded on a <code>1/(N*N)</code> scale.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Specify the size of the sourced video. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
The default value is <code>320x240</code>.
</p>
<p>This option is not available with the <code>haldclutsrc</code> filter.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Specify the frame rate of the sourced video, as the number of frames
generated per second. It has to be a string in the format
<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a floating point
number or a valid video frame rate abbreviation. The default value is
"25".
</p>
</dd>
<dt><samp>sar</samp></dt>
<dd><p>Set the sample aspect ratio of the sourced video.
</p>
</dd>
<dt><samp>duration, d</samp></dt>
<dd><p>Set the duration of the sourced video. See
<a href="ffmpeg-utils.html#time-duration-syntax">(ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual</a>
for the accepted syntax.
</p>
<p>If not specified, or the expressed duration is negative, the video is
supposed to be generated forever.
</p>
</dd>
<dt><samp>decimals, n</samp></dt>
<dd><p>Set the number of decimals to show in the timestamp, only available in the
<code>testsrc</code> source.
</p>
<p>The displayed timestamp value will correspond to the original
timestamp value multiplied by the power of 10 of the specified
value. Default value is 0.
</p></dd>
</dl>
<p>For example the following:
</p><div class="example">
<pre class="example">testsrc=duration=5.3:size=qcif:rate=10
</pre></div>
<p>will generate a video with a duration of 5.3 seconds, with size
176x144 and a frame rate of 10 frames per second.
</p>
<p>The following graph description will generate a red source
with an opacity of 0.2, with size "qcif" and a frame rate of 10
frames per second.
</p><div class="example">
<pre class="example">color=c=red@0.2:s=qcif:r=10
</pre></div>
<p>If the input content is to be ignored, <code>nullsrc</code> can be used. The
following command generates noise in the luminance plane by employing
the <code>geq</code> filter:
</p><div class="example">
<pre class="example">nullsrc=s=256x256, geq=random(1)*255:128:128
</pre></div>
<a name="Commands-8"></a>
<h4 class="subsection">38.7.1 Commands<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-8" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-8" aria-hidden="true">TOC</a></span></h4>
<p>The <code>color</code> source supports the following commands:
</p>
<dl compact="compact">
<dt><samp>c, color</samp></dt>
<dd><p>Set the color of the created image. Accepts the same syntax of the
corresponding <samp>color</samp> option.
</p></dd>
</dl>
<a name="Video-Sinks"></a>
<h2 class="chapter">39 Video Sinks<span class="pull-right"><a class="anchor hidden-xs" href="#Video-Sinks" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-Sinks" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available video sinks.
</p>
<a name="buffersink"></a>
<h3 class="section">39.1 buffersink<span class="pull-right"><a class="anchor hidden-xs" href="#buffersink" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-buffersink" aria-hidden="true">TOC</a></span></h3>
<p>Buffer video frames, and make them available to the end of the filter
graph.
</p>
<p>This sink is mainly intended for programmatic use, in particular
through the interface defined in <samp>libavfilter/buffersink.h</samp>
or the options system.
</p>
<p>It accepts a pointer to an AVBufferSinkContext structure, which
defines the incoming buffers’ formats, to be passed as the opaque
parameter to <code>avfilter_init_filter</code> for initialization.
</p>
<a name="nullsink"></a>
<h3 class="section">39.2 nullsink<span class="pull-right"><a class="anchor hidden-xs" href="#nullsink" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-nullsink" aria-hidden="true">TOC</a></span></h3>
<p>Null video sink: do absolutely nothing with the input video. It is
mainly useful as a template and for use in analysis / debugging
tools.
</p>
<a name="Multimedia-Filters"></a>
<h2 class="chapter">40 Multimedia Filters<span class="pull-right"><a class="anchor hidden-xs" href="#Multimedia-Filters" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Multimedia-Filters" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available multimedia filters.
</p>
<a name="aphasemeter"></a>
<h3 class="section">40.1 aphasemeter<span class="pull-right"><a class="anchor hidden-xs" href="#aphasemeter" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-aphasemeter" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a video output, displaying the audio phase.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rate, r</samp></dt>
<dd><p>Set the output frame rate. Default value is <code>25</code>.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set the video size for the output. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default value is <code>800x400</code>.
</p>
</dd>
<dt><samp>rc</samp></dt>
<dt><samp>gc</samp></dt>
<dt><samp>bc</samp></dt>
<dd><p>Specify the red, green, blue contrast. Default values are <code>2</code>,
<code>7</code> and <code>1</code>.
Allowed range is <code>[0, 255]</code>.
</p>
</dd>
<dt><samp>mpc</samp></dt>
<dd><p>Set color which will be used for drawing median phase. If color is
<code>none</code> which is default, no median phase value will be drawn.
</p></dd>
</dl>
<p>The filter also exports the frame metadata <code>lavfi.aphasemeter.phase</code> which
represents mean phase of current audio frame. Value is in range <code>[-1, 1]</code>.
The <code>-1</code> means left and right channels are completely out of phase and
<code>1</code> means channels are in phase.
</p>
<a name="avectorscope"></a>
<h3 class="section">40.2 avectorscope<span class="pull-right"><a class="anchor hidden-xs" href="#avectorscope" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-avectorscope" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a video output, representing the audio vector
scope.
</p>
<p>The filter is used to measure the difference between channels of stereo
audio stream. A monoaural signal, consisting of identical left and right
signal, results in straight vertical line. Any stereo separation is visible
as a deviation from this line, creating a Lissajous figure.
If the straight (or deviation from it) but horizontal line appears this
indicates that the left and right channels are out of phase.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>mode, m</samp></dt>
<dd><p>Set the vectorscope mode.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>lissajous</samp>’</dt>
<dd><p>Lissajous rotated by 45 degrees.
</p>
</dd>
<dt>‘<samp>lissajous_xy</samp>’</dt>
<dd><p>Same as above but not rotated.
</p>
</dd>
<dt>‘<samp>polar</samp>’</dt>
<dd><p>Shape resembling half of circle.
</p></dd>
</dl>
<p>Default value is ‘<samp>lissajous</samp>’.
</p>
</dd>
<dt><samp>size, s</samp></dt>
<dd><p>Set the video size for the output. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default value is <code>400x400</code>.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Set the output frame rate. Default value is <code>25</code>.
</p>
</dd>
<dt><samp>rc</samp></dt>
<dt><samp>gc</samp></dt>
<dt><samp>bc</samp></dt>
<dt><samp>ac</samp></dt>
<dd><p>Specify the red, green, blue and alpha contrast. Default values are <code>40</code>,
<code>160</code>, <code>80</code> and <code>255</code>.
Allowed range is <code>[0, 255]</code>.
</p>
</dd>
<dt><samp>rf</samp></dt>
<dt><samp>gf</samp></dt>
<dt><samp>bf</samp></dt>
<dt><samp>af</samp></dt>
<dd><p>Specify the red, green, blue and alpha fade. Default values are <code>15</code>,
<code>10</code>, <code>5</code> and <code>5</code>.
Allowed range is <code>[0, 255]</code>.
</p>
</dd>
<dt><samp>zoom</samp></dt>
<dd><p>Set the zoom factor. Default value is <code>1</code>. Allowed range is <code>[1, 10]</code>.
</p></dd>
</dl>
<a name="Examples-108"></a>
<h4 class="subsection">40.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-108" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-108" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Complete example using <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
</pre></div>
</li></ul>
<a name="concat-3"></a>
<h3 class="section">40.3 concat<span class="pull-right"><a class="anchor hidden-xs" href="#concat-3" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-concat-3" aria-hidden="true">TOC</a></span></h3>
<p>Concatenate audio and video streams, joining them together one after the
other.
</p>
<p>The filter works on segments of synchronized video and audio streams. All
segments must have the same number of streams of each type, and that will
also be the number of streams at output.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>Set the number of segments. Default is 2.
</p>
</dd>
<dt><samp>v</samp></dt>
<dd><p>Set the number of output video streams, that is also the number of video
streams in each segment. Default is 1.
</p>
</dd>
<dt><samp>a</samp></dt>
<dd><p>Set the number of output audio streams, that is also the number of audio
streams in each segment. Default is 0.
</p>
</dd>
<dt><samp>unsafe</samp></dt>
<dd><p>Activate unsafe mode: do not fail if segments have a different format.
</p>
</dd>
</dl>
<p>The filter has <var>v</var>+<var>a</var> outputs: first <var>v</var> video outputs, then
<var>a</var> audio outputs.
</p>
<p>There are <var>n</var>x(<var>v</var>+<var>a</var>) inputs: first the inputs for the first
segment, in the same order as the outputs, then the inputs for the second
segment, etc.
</p>
<p>Related streams do not always have exactly the same duration, for various
reasons including codec frame size or sloppy authoring. For that reason,
related synchronized streams (e.g. a video and its audio track) should be
concatenated at once. The concat filter will use the duration of the longest
stream in each segment (except the last one), and if necessary pad shorter
audio streams with silence.
</p>
<p>For this filter to work correctly, all segments must start at timestamp 0.
</p>
<p>All corresponding streams must have the same parameters in all segments; the
filtering system will automatically select a common pixel format for video
streams, and a common sample format, sample rate and channel layout for
audio streams, but other settings, such as resolution, must be converted
explicitly by the user.
</p>
<p>Different frame rates are acceptable but will result in variable frame rate
at output; be sure to configure the output file to handle it.
</p>
<a name="Examples-109"></a>
<h4 class="subsection">40.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-109" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-109" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Concatenate an opening, an episode and an ending, all in bilingual version
(video in stream 0, audio in streams 1 and 2):
<div class="example">
<pre class="example">ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
'[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
concat=n=3:v=1:a=2 [v] [a1] [a2]' \
-map '[v]' -map '[a1]' -map '[a2]' output.mkv
</pre></div>
</li><li> Concatenate two parts, handling audio and video separately, using the
(a)movie sources, and adjusting the resolution:
<div class="example">
<pre class="example">movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
[v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
</pre></div>
<p>Note that a desync will happen at the stitch if the audio and video streams
do not have exactly the same duration in the first file.
</p>
</li></ul>
<a name="ebur128"></a><a name="ebur128-1"></a>
<h3 class="section">40.4 ebur128<span class="pull-right"><a class="anchor hidden-xs" href="#ebur128-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-ebur128-1" aria-hidden="true">TOC</a></span></h3>
<p>EBU R128 scanner filter. This filter takes an audio stream as input and outputs
it unchanged. By default, it logs a message at a frequency of 10Hz with the
Momentary loudness (identified by <code>M</code>), Short-term loudness (<code>S</code>),
Integrated loudness (<code>I</code>) and Loudness Range (<code>LRA</code>).
</p>
<p>The filter also has a video output (see the <var>video</var> option) with a real
time graph to observe the loudness evolution. The graphic contains the logged
message mentioned above, so it is not printed anymore when this option is set,
unless the verbose logging is set. The main graphing area contains the
short-term loudness (3 seconds of analysis), and the gauge on the right is for
the momentary loudness (400 milliseconds).
</p>
<p>More information about the Loudness Recommendation EBU R128 on
<a href="http://tech.ebu.ch/loudness">http://tech.ebu.ch/loudness</a>.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>video</samp></dt>
<dd><p>Activate the video output. The audio stream is passed unchanged whether this
option is set or no. The video stream will be the first output stream if
activated. Default is <code>0</code>.
</p>
</dd>
<dt><samp>size</samp></dt>
<dd><p>Set the video size. This option is for video only. For the syntax of this
option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default and minimum resolution is <code>640x480</code>.
</p>
</dd>
<dt><samp>meter</samp></dt>
<dd><p>Set the EBU scale meter. Default is <code>9</code>. Common values are <code>9</code> and
<code>18</code>, respectively for EBU scale meter +9 and EBU scale meter +18. Any
other integer value between this range is allowed.
</p>
</dd>
<dt><samp>metadata</samp></dt>
<dd><p>Set metadata injection. If set to <code>1</code>, the audio input will be segmented
into 100ms output frames, each of them containing various loudness information
in metadata. All the metadata keys are prefixed with <code>lavfi.r128.</code>.
</p>
<p>Default is <code>0</code>.
</p>
</dd>
<dt><samp>framelog</samp></dt>
<dd><p>Force the frame logging level.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>info</samp>’</dt>
<dd><p>information logging level
</p></dd>
<dt>‘<samp>verbose</samp>’</dt>
<dd><p>verbose logging level
</p></dd>
</dl>
<p>By default, the logging level is set to <var>info</var>. If the <samp>video</samp> or
the <samp>metadata</samp> options are set, it switches to <var>verbose</var>.
</p>
</dd>
<dt><samp>peak</samp></dt>
<dd><p>Set peak mode(s).
</p>
<p>Available modes can be cumulated (the option is a <code>flag</code> type). Possible
values are:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>Disable any peak mode (default).
</p></dd>
<dt>‘<samp>sample</samp>’</dt>
<dd><p>Enable sample-peak mode.
</p>
<p>Simple peak mode looking for the higher sample value. It logs a message
for sample-peak (identified by <code>SPK</code>).
</p></dd>
<dt>‘<samp>true</samp>’</dt>
<dd><p>Enable true-peak mode.
</p>
<p>If enabled, the peak lookup is done on an over-sampled version of the input
stream for better peak accuracy. It logs a message for true-peak.
(identified by <code>TPK</code>) and true-peak per frame (identified by <code>FTPK</code>).
This mode requires a build with <code>libswresample</code>.
</p></dd>
</dl>
</dd>
</dl>
<a name="Examples-110"></a>
<h4 class="subsection">40.4.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-110" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-110" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Real-time graph using <code>ffplay</code>, with a EBU scale meter +18:
<div class="example">
<pre class="example">ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
</pre></div>
</li><li> Run an analysis with <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
</pre></div>
</li></ul>
<a name="interleave_002c-ainterleave"></a>
<h3 class="section">40.5 interleave, ainterleave<span class="pull-right"><a class="anchor hidden-xs" href="#interleave_002c-ainterleave" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-interleave_002c-ainterleave" aria-hidden="true">TOC</a></span></h3>
<p>Temporally interleave frames from several inputs.
</p>
<p><code>interleave</code> works with video inputs, <code>ainterleave</code> with audio.
</p>
<p>These filters read frames from several inputs and send the oldest
queued frame to the output.
</p>
<p>Input streams must have a well defined, monotonically increasing frame
timestamp values.
</p>
<p>In order to submit one frame to output, these filters need to enqueue
at least one frame for each input, so they cannot work in case one
input is not yet terminated and will not receive incoming frames.
</p>
<p>For example consider the case when one input is a <code>select</code> filter
which always drop input frames. The <code>interleave</code> filter will keep
reading from that input, but it will never be able to send new frames
to output until the input will send an end-of-stream signal.
</p>
<p>Also, depending on inputs synchronization, the filters will drop
frames in case one input receives more frames than the other ones, and
the queue is already filled.
</p>
<p>These filters accept the following options:
</p>
<dl compact="compact">
<dt><samp>nb_inputs, n</samp></dt>
<dd><p>Set the number of different inputs, it is 2 by default.
</p></dd>
</dl>
<a name="Examples-111"></a>
<h4 class="subsection">40.5.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-111" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-111" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Interleave frames belonging to different streams using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
</pre></div>
</li><li> Add flickering blur effect:
<div class="example">
<pre class="example">select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
</pre></div>
</li></ul>
<a name="perms_002c-aperms"></a>
<h3 class="section">40.6 perms, aperms<span class="pull-right"><a class="anchor hidden-xs" href="#perms_002c-aperms" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-perms_002c-aperms" aria-hidden="true">TOC</a></span></h3>
<p>Set read/write permissions for the output frames.
</p>
<p>These filters are mainly aimed at developers to test direct path in the
following filter in the filtergraph.
</p>
<p>The filters accept the following options:
</p>
<dl compact="compact">
<dt><samp>mode</samp></dt>
<dd><p>Select the permissions mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>Do nothing. This is the default.
</p></dd>
<dt>‘<samp>ro</samp>’</dt>
<dd><p>Set all the output frames read-only.
</p></dd>
<dt>‘<samp>rw</samp>’</dt>
<dd><p>Set all the output frames directly writable.
</p></dd>
<dt>‘<samp>toggle</samp>’</dt>
<dd><p>Make the frame read-only if writable, and writable if read-only.
</p></dd>
<dt>‘<samp>random</samp>’</dt>
<dd><p>Set each output frame read-only or writable randomly.
</p></dd>
</dl>
</dd>
<dt><samp>seed</samp></dt>
<dd><p>Set the seed for the <var>random</var> mode, must be an integer included between
<code>0</code> and <code>UINT32_MAX</code>. If not specified, or if explicitly set to
<code>-1</code>, the filter will try to use a good random seed on a best effort
basis.
</p></dd>
</dl>
<p>Note: in case of auto-inserted filter between the permission filter and the
following one, the permission might not be received as expected in that
following filter. Inserting a <a href="#format">format</a> or <a href="#aformat">aformat</a> filter before the
perms/aperms filter can avoid this problem.
</p>
<a name="select_002c-aselect"></a>
<h3 class="section">40.7 select, aselect<span class="pull-right"><a class="anchor hidden-xs" href="#select_002c-aselect" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-select_002c-aselect" aria-hidden="true">TOC</a></span></h3>
<p>Select frames to pass in output.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>expr, e</samp></dt>
<dd><p>Set expression, which is evaluated for each input frame.
</p>
<p>If the expression is evaluated to zero, the frame is discarded.
</p>
<p>If the evaluation result is negative or NaN, the frame is sent to the
first output; otherwise it is sent to the output with index
<code>ceil(val)-1</code>, assuming that the input index starts from 0.
</p>
<p>For example a value of <code>1.2</code> corresponds to the output with index
<code>ceil(1.2)-1 = 2-1 = 1</code>, that is the second output.
</p>
</dd>
<dt><samp>outputs, n</samp></dt>
<dd><p>Set the number of outputs. The output to which to send the selected
frame is based on the result of the evaluation. Default value is 1.
</p></dd>
</dl>
<p>The expression can contain the following constants:
</p>
<dl compact="compact">
<dt><samp>n</samp></dt>
<dd><p>The (sequential) number of the filtered frame, starting from 0.
</p>
</dd>
<dt><samp>selected_n</samp></dt>
<dd><p>The (sequential) number of the selected frame, starting from 0.
</p>
</dd>
<dt><samp>prev_selected_n</samp></dt>
<dd><p>The sequential number of the last selected frame. It’s NAN if undefined.
</p>
</dd>
<dt><samp>TB</samp></dt>
<dd><p>The timebase of the input timestamps.
</p>
</dd>
<dt><samp>pts</samp></dt>
<dd><p>The PTS (Presentation TimeStamp) of the filtered video frame,
expressed in <var>TB</var> units. It’s NAN if undefined.
</p>
</dd>
<dt><samp>t</samp></dt>
<dd><p>The PTS of the filtered video frame,
expressed in seconds. It’s NAN if undefined.
</p>
</dd>
<dt><samp>prev_pts</samp></dt>
<dd><p>The PTS of the previously filtered video frame. It’s NAN if undefined.
</p>
</dd>
<dt><samp>prev_selected_pts</samp></dt>
<dd><p>The PTS of the last previously filtered video frame. It’s NAN if undefined.
</p>
</dd>
<dt><samp>prev_selected_t</samp></dt>
<dd><p>The PTS of the last previously selected video frame. It’s NAN if undefined.
</p>
</dd>
<dt><samp>start_pts</samp></dt>
<dd><p>The PTS of the first video frame in the video. It’s NAN if undefined.
</p>
</dd>
<dt><samp>start_t</samp></dt>
<dd><p>The time of the first video frame in the video. It’s NAN if undefined.
</p>
</dd>
<dt><samp>pict_type <em>(video only)</em></samp></dt>
<dd><p>The type of the filtered frame. It can assume one of the following
values:
</p><dl compact="compact">
<dt><samp>I</samp></dt>
<dt><samp>P</samp></dt>
<dt><samp>B</samp></dt>
<dt><samp>S</samp></dt>
<dt><samp>SI</samp></dt>
<dt><samp>SP</samp></dt>
<dt><samp>BI</samp></dt>
</dl>
</dd>
<dt><samp>interlace_type <em>(video only)</em></samp></dt>
<dd><p>The frame interlace type. It can assume one of the following values:
</p><dl compact="compact">
<dt><samp>PROGRESSIVE</samp></dt>
<dd><p>The frame is progressive (not interlaced).
</p></dd>
<dt><samp>TOPFIRST</samp></dt>
<dd><p>The frame is top-field-first.
</p></dd>
<dt><samp>BOTTOMFIRST</samp></dt>
<dd><p>The frame is bottom-field-first.
</p></dd>
</dl>
</dd>
<dt><samp>consumed_sample_n <em>(audio only)</em></samp></dt>
<dd><p>the number of selected samples before the current frame
</p>
</dd>
<dt><samp>samples_n <em>(audio only)</em></samp></dt>
<dd><p>the number of samples in the current frame
</p>
</dd>
<dt><samp>sample_rate <em>(audio only)</em></samp></dt>
<dd><p>the input sample rate
</p>
</dd>
<dt><samp>key</samp></dt>
<dd><p>This is 1 if the filtered frame is a key-frame, 0 otherwise.
</p>
</dd>
<dt><samp>pos</samp></dt>
<dd><p>the position in the file of the filtered frame, -1 if the information
is not available (e.g. for synthetic video)
</p>
</dd>
<dt><samp>scene <em>(video only)</em></samp></dt>
<dd><p>value between 0 and 1 to indicate a new scene; a low value reflects a low
probability for the current frame to introduce a new scene, while a higher
value means the current frame is more likely to be one (see the example below)
</p>
</dd>
</dl>
<p>The default value of the select expression is "1".
</p>
<a name="Examples-112"></a>
<h4 class="subsection">40.7.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-112" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-112" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Select all frames in input:
<div class="example">
<pre class="example">select
</pre></div>
<p>The example above is the same as:
</p><div class="example">
<pre class="example">select=1
</pre></div>
</li><li> Skip all frames:
<div class="example">
<pre class="example">select=0
</pre></div>
</li><li> Select only I-frames:
<div class="example">
<pre class="example">select='eq(pict_type\,I)'
</pre></div>
</li><li> Select one frame every 100:
<div class="example">
<pre class="example">select='not(mod(n\,100))'
</pre></div>
</li><li> Select only frames contained in the 10-20 time interval:
<div class="example">
<pre class="example">select=between(t\,10\,20)
</pre></div>
</li><li> Select only I frames contained in the 10-20 time interval:
<div class="example">
<pre class="example">select=between(t\,10\,20)*eq(pict_type\,I)
</pre></div>
</li><li> Select frames with a minimum distance of 10 seconds:
<div class="example">
<pre class="example">select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
</pre></div>
</li><li> Use aselect to select only audio frames with samples number > 100:
<div class="example">
<pre class="example">aselect='gt(samples_n\,100)'
</pre></div>
</li><li> Create a mosaic of the first scenes:
<div class="example">
<pre class="example">ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
</pre></div>
<p>Comparing <var>scene</var> against a value between 0.3 and 0.5 is generally a sane
choice.
</p>
</li><li> Send even and odd frames to separate outputs, and compose them:
<div class="example">
<pre class="example">select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
</pre></div>
</li></ul>
<a name="sendcmd_002c-asendcmd"></a>
<h3 class="section">40.8 sendcmd, asendcmd<span class="pull-right"><a class="anchor hidden-xs" href="#sendcmd_002c-asendcmd" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-sendcmd_002c-asendcmd" aria-hidden="true">TOC</a></span></h3>
<p>Send commands to filters in the filtergraph.
</p>
<p>These filters read commands to be sent to other filters in the
filtergraph.
</p>
<p><code>sendcmd</code> must be inserted between two video filters,
<code>asendcmd</code> must be inserted between two audio filters, but apart
from that they act the same way.
</p>
<p>The specification of commands can be provided in the filter arguments
with the <var>commands</var> option, or in a file specified by the
<var>filename</var> option.
</p>
<p>These filters accept the following options:
</p><dl compact="compact">
<dt><samp>commands, c</samp></dt>
<dd><p>Set the commands to be read and sent to the other filters.
</p></dd>
<dt><samp>filename, f</samp></dt>
<dd><p>Set the filename of the commands to be read and sent to the other
filters.
</p></dd>
</dl>
<a name="Commands-syntax"></a>
<h4 class="subsection">40.8.1 Commands syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Commands-syntax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Commands-syntax" aria-hidden="true">TOC</a></span></h4>
<p>A commands description consists of a sequence of interval
specifications, comprising a list of commands to be executed when a
particular event related to that interval occurs. The occurring event
is typically the current frame time entering or leaving a given time
interval.
</p>
<p>An interval is specified by the following syntax:
</p><div class="example">
<pre class="example"><var>START</var>[-<var>END</var>] <var>COMMANDS</var>;
</pre></div>
<p>The time interval is specified by the <var>START</var> and <var>END</var> times.
<var>END</var> is optional and defaults to the maximum time.
</p>
<p>The current frame time is considered within the specified interval if
it is included in the interval [<var>START</var>, <var>END</var>), that is when
the time is greater or equal to <var>START</var> and is lesser than
<var>END</var>.
</p>
<p><var>COMMANDS</var> consists of a sequence of one or more command
specifications, separated by ",", relating to that interval. The
syntax of a command specification is given by:
</p><div class="example">
<pre class="example">[<var>FLAGS</var>] <var>TARGET</var> <var>COMMAND</var> <var>ARG</var>
</pre></div>
<p><var>FLAGS</var> is optional and specifies the type of events relating to
the time interval which enable sending the specified command, and must
be a non-null sequence of identifier flags separated by "+" or "|" and
enclosed between "[" and "]".
</p>
<p>The following flags are recognized:
</p><dl compact="compact">
<dt><samp>enter</samp></dt>
<dd><p>The command is sent when the current frame timestamp enters the
specified interval. In other words, the command is sent when the
previous frame timestamp was not in the given interval, and the
current is.
</p>
</dd>
<dt><samp>leave</samp></dt>
<dd><p>The command is sent when the current frame timestamp leaves the
specified interval. In other words, the command is sent when the
previous frame timestamp was in the given interval, and the
current is not.
</p></dd>
</dl>
<p>If <var>FLAGS</var> is not specified, a default value of <code>[enter]</code> is
assumed.
</p>
<p><var>TARGET</var> specifies the target of the command, usually the name of
the filter class or a specific filter instance name.
</p>
<p><var>COMMAND</var> specifies the name of the command for the target filter.
</p>
<p><var>ARG</var> is optional and specifies the optional list of argument for
the given <var>COMMAND</var>.
</p>
<p>Between one interval specification and another, whitespaces, or
sequences of characters starting with <code>#</code> until the end of line,
are ignored and can be used to annotate comments.
</p>
<p>A simplified BNF description of the commands specification syntax
follows:
</p><div class="example">
<pre class="example"><var>COMMAND_FLAG</var> ::= "enter" | "leave"
<var>COMMAND_FLAGS</var> ::= <var>COMMAND_FLAG</var> [(+|"|")<var>COMMAND_FLAG</var>]
<var>COMMAND</var> ::= ["[" <var>COMMAND_FLAGS</var> "]"] <var>TARGET</var> <var>COMMAND</var> [<var>ARG</var>]
<var>COMMANDS</var> ::= <var>COMMAND</var> [,<var>COMMANDS</var>]
<var>INTERVAL</var> ::= <var>START</var>[-<var>END</var>] <var>COMMANDS</var>
<var>INTERVALS</var> ::= <var>INTERVAL</var>[;<var>INTERVALS</var>]
</pre></div>
<a name="Examples-113"></a>
<h4 class="subsection">40.8.2 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-113" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-113" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Specify audio tempo change at second 4:
<div class="example">
<pre class="example">asendcmd=c='4.0 atempo tempo 1.5',atempo
</pre></div>
</li><li> Specify a list of drawtext and hue commands in a file.
<div class="example">
<pre class="example"># show text in the interval 5-10
5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
# desaturate the image in the interval 15-20
15.0-20.0 [enter] hue s 0,
[enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
[leave] hue s 1,
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
# apply an exponential saturation fade-out effect, starting from time 25
25 [enter] hue s exp(25-t)
</pre></div>
<p>A filtergraph allowing to read and process the above command list
stored in a file <samp>test.cmd</samp>, can be specified with:
</p><div class="example">
<pre class="example">sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
</pre></div>
</li></ul>
<a name="setpts"></a><a name="setpts_002c-asetpts"></a>
<h3 class="section">40.9 setpts, asetpts<span class="pull-right"><a class="anchor hidden-xs" href="#setpts_002c-asetpts" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-setpts_002c-asetpts" aria-hidden="true">TOC</a></span></h3>
<p>Change the PTS (presentation timestamp) of the input frames.
</p>
<p><code>setpts</code> works on video frames, <code>asetpts</code> on audio frames.
</p>
<p>This filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>expr</samp></dt>
<dd><p>The expression which is evaluated for each frame to construct its timestamp.
</p>
</dd>
</dl>
<p>The expression is evaluated through the eval API and can contain the following
constants:
</p>
<dl compact="compact">
<dt><samp>FRAME_RATE</samp></dt>
<dd><p>frame rate, only defined for constant frame-rate video
</p>
</dd>
<dt><samp>PTS</samp></dt>
<dd><p>The presentation timestamp in input
</p>
</dd>
<dt><samp>N</samp></dt>
<dd><p>The count of the input frame for video or the number of consumed samples,
not including the current frame for audio, starting from 0.
</p>
</dd>
<dt><samp>NB_CONSUMED_SAMPLES</samp></dt>
<dd><p>The number of consumed samples, not including the current frame (only
audio)
</p>
</dd>
<dt><samp>NB_SAMPLES, S</samp></dt>
<dd><p>The number of samples in the current frame (only audio)
</p>
</dd>
<dt><samp>SAMPLE_RATE, SR</samp></dt>
<dd><p>The audio sample rate.
</p>
</dd>
<dt><samp>STARTPTS</samp></dt>
<dd><p>The PTS of the first frame.
</p>
</dd>
<dt><samp>STARTT</samp></dt>
<dd><p>the time in seconds of the first frame
</p>
</dd>
<dt><samp>INTERLACED</samp></dt>
<dd><p>State whether the current frame is interlaced.
</p>
</dd>
<dt><samp>T</samp></dt>
<dd><p>the time in seconds of the current frame
</p>
</dd>
<dt><samp>POS</samp></dt>
<dd><p>original position in the file of the frame, or undefined if undefined
for the current frame
</p>
</dd>
<dt><samp>PREV_INPTS</samp></dt>
<dd><p>The previous input PTS.
</p>
</dd>
<dt><samp>PREV_INT</samp></dt>
<dd><p>previous input time in seconds
</p>
</dd>
<dt><samp>PREV_OUTPTS</samp></dt>
<dd><p>The previous output PTS.
</p>
</dd>
<dt><samp>PREV_OUTT</samp></dt>
<dd><p>previous output time in seconds
</p>
</dd>
<dt><samp>RTCTIME</samp></dt>
<dd><p>The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
instead.
</p>
</dd>
<dt><samp>RTCSTART</samp></dt>
<dd><p>The wallclock (RTC) time at the start of the movie in microseconds.
</p>
</dd>
<dt><samp>TB</samp></dt>
<dd><p>The timebase of the input timestamps.
</p>
</dd>
</dl>
<a name="Examples-114"></a>
<h4 class="subsection">40.9.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-114" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-114" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Start counting PTS from zero
<div class="example">
<pre class="example">setpts=PTS-STARTPTS
</pre></div>
</li><li> Apply fast motion effect:
<div class="example">
<pre class="example">setpts=0.5*PTS
</pre></div>
</li><li> Apply slow motion effect:
<div class="example">
<pre class="example">setpts=2.0*PTS
</pre></div>
</li><li> Set fixed rate of 25 frames per second:
<div class="example">
<pre class="example">setpts=N/(25*TB)
</pre></div>
</li><li> Set fixed rate 25 fps with some jitter:
<div class="example">
<pre class="example">setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
</pre></div>
</li><li> Apply an offset of 10 seconds to the input PTS:
<div class="example">
<pre class="example">setpts=PTS+10/TB
</pre></div>
</li><li> Generate timestamps from a "live source" and rebase onto the current timebase:
<div class="example">
<pre class="example">setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
</pre></div>
</li><li> Generate timestamps by counting samples:
<div class="example">
<pre class="example">asetpts=N/SR/TB
</pre></div>
</li></ul>
<a name="settb_002c-asettb"></a>
<h3 class="section">40.10 settb, asettb<span class="pull-right"><a class="anchor hidden-xs" href="#settb_002c-asettb" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-settb_002c-asettb" aria-hidden="true">TOC</a></span></h3>
<p>Set the timebase to use for the output frames timestamps.
It is mainly useful for testing timebase configuration.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>expr, tb</samp></dt>
<dd><p>The expression which is evaluated into the output timebase.
</p>
</dd>
</dl>
<p>The value for <samp>tb</samp> is an arithmetic expression representing a
rational. The expression can contain the constants "AVTB" (the default
timebase), "intb" (the input timebase) and "sr" (the sample rate,
audio only). Default value is "intb".
</p>
<a name="Examples-115"></a>
<h4 class="subsection">40.10.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-115" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-115" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Set the timebase to 1/25:
<div class="example">
<pre class="example">settb=expr=1/25
</pre></div>
</li><li> Set the timebase to 1/10:
<div class="example">
<pre class="example">settb=expr=0.1
</pre></div>
</li><li> Set the timebase to 1001/1000:
<div class="example">
<pre class="example">settb=1+0.001
</pre></div>
</li><li> Set the timebase to 2*intb:
<div class="example">
<pre class="example">settb=2*intb
</pre></div>
</li><li> Set the default timebase value:
<div class="example">
<pre class="example">settb=AVTB
</pre></div>
</li></ul>
<a name="showcqt"></a>
<h3 class="section">40.11 showcqt<span class="pull-right"><a class="anchor hidden-xs" href="#showcqt" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showcqt" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a video output representing
frequency spectrum logarithmically (using constant Q transform with
Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves).
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>volume</samp></dt>
<dd><p>Specify transform volume (multiplier) expression. The expression can contain
variables:
</p><dl compact="compact">
<dt><samp>frequency, freq, f</samp></dt>
<dd><p>the frequency where transform is evaluated
</p></dd>
<dt><samp>timeclamp, tc</samp></dt>
<dd><p>value of timeclamp option
</p></dd>
</dl>
<p>and functions:
</p><dl compact="compact">
<dt><samp>a_weighting(f)</samp></dt>
<dd><p>A-weighting of equal loudness
</p></dd>
<dt><samp>b_weighting(f)</samp></dt>
<dd><p>B-weighting of equal loudness
</p></dd>
<dt><samp>c_weighting(f)</samp></dt>
<dd><p>C-weighting of equal loudness
</p></dd>
</dl>
<p>Default value is <code>16</code>.
</p>
</dd>
<dt><samp>tlength</samp></dt>
<dd><p>Specify transform length expression. The expression can contain variables:
</p><dl compact="compact">
<dt><samp>frequency, freq, f</samp></dt>
<dd><p>the frequency where transform is evaluated
</p></dd>
<dt><samp>timeclamp, tc</samp></dt>
<dd><p>value of timeclamp option
</p></dd>
</dl>
<p>Default value is <code>384/f*tc/(384/f+tc)</code>.
</p>
</dd>
<dt><samp>timeclamp</samp></dt>
<dd><p>Specify the transform timeclamp. At low frequency, there is trade-off between
accuracy in time domain and frequency domain. If timeclamp is lower,
event in time domain is represented more accurately (such as fast bass drum),
otherwise event in frequency domain is represented more accurately
(such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is <code>0.17</code>.
</p>
</dd>
<dt><samp>coeffclamp</samp></dt>
<dd><p>Specify the transform coeffclamp. If coeffclamp is lower, transform is
more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0].
Default value is <code>1.0</code>.
</p>
</dd>
<dt><samp>gamma</samp></dt>
<dd><p>Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma
makes the spectrum having more range. Acceptable value is [1.0, 7.0].
Default value is <code>3.0</code>.
</p>
</dd>
<dt><samp>gamma2</samp></dt>
<dd><p>Specify gamma of bargraph. Acceptable value is [1.0, 7.0].
Default value is <code>1.0</code>.
</p>
</dd>
<dt><samp>fontfile</samp></dt>
<dd><p>Specify font file for use with freetype. If not specified, use embedded font.
</p>
</dd>
<dt><samp>fontcolor</samp></dt>
<dd><p>Specify font color expression. This is arithmetic expression that should return
integer value 0xRRGGBB. The expression can contain variables:
</p><dl compact="compact">
<dt><samp>frequency, freq, f</samp></dt>
<dd><p>the frequency where transform is evaluated
</p></dd>
<dt><samp>timeclamp, tc</samp></dt>
<dd><p>value of timeclamp option
</p></dd>
</dl>
<p>and functions:
</p><dl compact="compact">
<dt><samp>midi(f)</samp></dt>
<dd><p>midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
</p></dd>
<dt><samp>r(x), g(x), b(x)</samp></dt>
<dd><p>red, green, and blue value of intensity x
</p></dd>
</dl>
<p>Default value is <code>st(0, (midi(f)-59.5)/12);
st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
r(1-ld(1)) + b(ld(1))</code>
</p>
</dd>
<dt><samp>fullhd</samp></dt>
<dd><p>If set to 1 (the default), the video size is 1920x1080 (full HD),
if set to 0, the video size is 960x540. Use this option to make CPU usage lower.
</p>
</dd>
<dt><samp>fps</samp></dt>
<dd><p>Specify video fps. Default value is <code>25</code>.
</p>
</dd>
<dt><samp>count</samp></dt>
<dd><p>Specify number of transform per frame, so there are fps*count transforms
per second. Note that audio data rate must be divisible by fps*count.
Default value is <code>6</code>.
</p>
</dd>
</dl>
<a name="Examples-116"></a>
<h4 class="subsection">40.11.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-116" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-116" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Playing audio while showing the spectrum:
<div class="example">
<pre class="example">ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
</pre></div>
</li><li> Same as above, but with frame rate 30 fps:
<div class="example">
<pre class="example">ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
</pre></div>
</li><li> Playing at 960x540 and lower CPU usage:
<div class="example">
<pre class="example">ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]'
</pre></div>
</li><li> A1 and its harmonics: A1, A2, (near)E3, A3:
<div class="example">
<pre class="example">ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
asplit[a][out1]; [a] showcqt [out0]'
</pre></div>
</li><li> Same as above, but with more accuracy in frequency domain (and slower):
<div class="example">
<pre class="example">ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
</pre></div>
</li><li> B-weighting of equal loudness
<div class="example">
<pre class="example">volume=16*b_weighting(f)
</pre></div>
</li><li> Lower Q factor
<div class="example">
<pre class="example">tlength=100/f*tc/(100/f+tc)
</pre></div>
</li><li> Custom fontcolor, C-note is colored green, others are colored blue
<div class="example">
<pre class="example">fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))'
</pre></div>
</li><li> Custom gamma, now spectrum is linear to the amplitude.
<div class="example">
<pre class="example">gamma=2:gamma2=2
</pre></div>
</li></ul>
<a name="showfreqs"></a>
<h3 class="section">40.12 showfreqs<span class="pull-right"><a class="anchor hidden-xs" href="#showfreqs" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showfreqs" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to video output representing the audio power spectrum.
Audio amplitude is on Y-axis while frequency is on X-axis.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>size, s</samp></dt>
<dd><p>Specify size of video. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default is <code>1024x512</code>.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set display mode.
This set how each frequency bin will be represented.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>line</samp>’</dt>
<dt>‘<samp>bar</samp>’</dt>
<dt>‘<samp>dot</samp>’</dt>
</dl>
<p>Default is <code>bar</code>.
</p>
</dd>
<dt><samp>ascale</samp></dt>
<dd><p>Set amplitude scale.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>lin</samp>’</dt>
<dd><p>Linear scale.
</p>
</dd>
<dt>‘<samp>sqrt</samp>’</dt>
<dd><p>Square root scale.
</p>
</dd>
<dt>‘<samp>cbrt</samp>’</dt>
<dd><p>Cubic root scale.
</p>
</dd>
<dt>‘<samp>log</samp>’</dt>
<dd><p>Logarithmic scale.
</p></dd>
</dl>
<p>Default is <code>log</code>.
</p>
</dd>
<dt><samp>fscale</samp></dt>
<dd><p>Set frequency scale.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>lin</samp>’</dt>
<dd><p>Linear scale.
</p>
</dd>
<dt>‘<samp>log</samp>’</dt>
<dd><p>Logarithmic scale.
</p>
</dd>
<dt>‘<samp>rlog</samp>’</dt>
<dd><p>Reverse logarithmic scale.
</p></dd>
</dl>
<p>Default is <code>lin</code>.
</p>
</dd>
<dt><samp>win_size</samp></dt>
<dd><p>Set window size.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>w16</samp>’</dt>
<dt>‘<samp>w32</samp>’</dt>
<dt>‘<samp>w64</samp>’</dt>
<dt>‘<samp>w128</samp>’</dt>
<dt>‘<samp>w256</samp>’</dt>
<dt>‘<samp>w512</samp>’</dt>
<dt>‘<samp>w1024</samp>’</dt>
<dt>‘<samp>w2048</samp>’</dt>
<dt>‘<samp>w4096</samp>’</dt>
<dt>‘<samp>w8192</samp>’</dt>
<dt>‘<samp>w16384</samp>’</dt>
<dt>‘<samp>w32768</samp>’</dt>
<dt>‘<samp>w65536</samp>’</dt>
</dl>
<p>Default is <code>w2048</code>
</p>
</dd>
<dt><samp>win_func</samp></dt>
<dd><p>Set windowing function.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>rect</samp>’</dt>
<dt>‘<samp>bartlett</samp>’</dt>
<dt>‘<samp>hanning</samp>’</dt>
<dt>‘<samp>hamming</samp>’</dt>
<dt>‘<samp>blackman</samp>’</dt>
<dt>‘<samp>welch</samp>’</dt>
<dt>‘<samp>flattop</samp>’</dt>
<dt>‘<samp>bharris</samp>’</dt>
<dt>‘<samp>bnuttall</samp>’</dt>
<dt>‘<samp>bhann</samp>’</dt>
<dt>‘<samp>sine</samp>’</dt>
<dt>‘<samp>nuttall</samp>’</dt>
</dl>
<p>Default is <code>hanning</code>.
</p>
</dd>
<dt><samp>overlap</samp></dt>
<dd><p>Set window overlap. In range <code>[0, 1]</code>. Default is <code>1</code>,
which means optimal overlap for selected window function will be picked.
</p>
</dd>
<dt><samp>averaging</samp></dt>
<dd><p>Set time averaging. Setting this to 0 will display current maximal peaks.
Default is <code>1</code>, which means time averaging is disabled.
</p>
</dd>
<dt><samp>color</samp></dt>
<dd><p>Specify list of colors separated by space or by ’|’ which will be used to
draw channel frequencies. Unrecognized or missing colors will be replaced
by white color.
</p></dd>
</dl>
<a name="showspectrum"></a>
<h3 class="section">40.13 showspectrum<span class="pull-right"><a class="anchor hidden-xs" href="#showspectrum" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showspectrum" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a video output, representing the audio frequency
spectrum.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>size, s</samp></dt>
<dd><p>Specify the video size for the output. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default value is <code>640x512</code>.
</p>
</dd>
<dt><samp>slide</samp></dt>
<dd><p>Specify how the spectrum should slide along the window.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>replace</samp>’</dt>
<dd><p>the samples start again on the left when they reach the right
</p></dd>
<dt>‘<samp>scroll</samp>’</dt>
<dd><p>the samples scroll from right to left
</p></dd>
<dt>‘<samp>fullframe</samp>’</dt>
<dd><p>frames are only produced when the samples reach the right
</p></dd>
</dl>
<p>Default value is <code>replace</code>.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Specify display mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>combined</samp>’</dt>
<dd><p>all channels are displayed in the same row
</p></dd>
<dt>‘<samp>separate</samp>’</dt>
<dd><p>all channels are displayed in separate rows
</p></dd>
</dl>
<p>Default value is ‘<samp>combined</samp>’.
</p>
</dd>
<dt><samp>color</samp></dt>
<dd><p>Specify display color mode.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>channel</samp>’</dt>
<dd><p>each channel is displayed in a separate color
</p></dd>
<dt>‘<samp>intensity</samp>’</dt>
<dd><p>each channel is is displayed using the same color scheme
</p></dd>
</dl>
<p>Default value is ‘<samp>channel</samp>’.
</p>
</dd>
<dt><samp>scale</samp></dt>
<dd><p>Specify scale used for calculating intensity color values.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>lin</samp>’</dt>
<dd><p>linear
</p></dd>
<dt>‘<samp>sqrt</samp>’</dt>
<dd><p>square root, default
</p></dd>
<dt>‘<samp>cbrt</samp>’</dt>
<dd><p>cubic root
</p></dd>
<dt>‘<samp>log</samp>’</dt>
<dd><p>logarithmic
</p></dd>
</dl>
<p>Default value is ‘<samp>sqrt</samp>’.
</p>
</dd>
<dt><samp>saturation</samp></dt>
<dd><p>Set saturation modifier for displayed colors. Negative values provide
alternative color scheme. <code>0</code> is no saturation at all.
Saturation must be in [-10.0, 10.0] range.
Default value is <code>1</code>.
</p>
</dd>
<dt><samp>win_func</samp></dt>
<dd><p>Set window function.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>none</samp>’</dt>
<dd><p>No samples pre-processing (do not expect this to be faster)
</p></dd>
<dt>‘<samp>hann</samp>’</dt>
<dd><p>Hann window
</p></dd>
<dt>‘<samp>hamming</samp>’</dt>
<dd><p>Hamming window
</p></dd>
<dt>‘<samp>blackman</samp>’</dt>
<dd><p>Blackman window
</p></dd>
</dl>
<p>Default value is <code>hann</code>.
</p></dd>
</dl>
<p>The usage is very similar to the showwaves filter; see the examples in that
section.
</p>
<a name="Examples-117"></a>
<h4 class="subsection">40.13.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-117" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-117" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Large window with logarithmic color scaling:
<div class="example">
<pre class="example">showspectrum=s=1280x480:scale=log
</pre></div>
</li><li> Complete example for a colored and sliding spectrum per channel using <code>ffplay</code>:
<div class="example">
<pre class="example">ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
</pre></div>
</li></ul>
<a name="showvolume"></a>
<h3 class="section">40.14 showvolume<span class="pull-right"><a class="anchor hidden-xs" href="#showvolume" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showvolume" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio volume to a video output.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>rate, r</samp></dt>
<dd><p>Set video rate.
</p>
</dd>
<dt><samp>b</samp></dt>
<dd><p>Set border width, allowed range is [0, 5]. Default is 1.
</p>
</dd>
<dt><samp>w</samp></dt>
<dd><p>Set channel width, allowed range is [40, 1080]. Default is 400.
</p>
</dd>
<dt><samp>h</samp></dt>
<dd><p>Set channel height, allowed range is [1, 100]. Default is 20.
</p>
</dd>
<dt><samp>f</samp></dt>
<dd><p>Set fade, allowed range is [1, 255]. Default is 20.
</p>
</dd>
<dt><samp>c</samp></dt>
<dd><p>Set volume color expression.
</p>
<p>The expression can use the following variables:
</p>
<dl compact="compact">
<dt><samp>VOLUME</samp></dt>
<dd><p>Current max volume of channel in dB.
</p>
</dd>
<dt><samp>CHANNEL</samp></dt>
<dd><p>Current channel number, starting from 0.
</p></dd>
</dl>
</dd>
<dt><samp>t</samp></dt>
<dd><p>If set, displays channel names. Default is enabled.
</p></dd>
</dl>
<a name="showwaves"></a>
<h3 class="section">40.15 showwaves<span class="pull-right"><a class="anchor hidden-xs" href="#showwaves" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showwaves" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a video output, representing the samples waves.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>size, s</samp></dt>
<dd><p>Specify the video size for the output. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default value is <code>600x240</code>.
</p>
</dd>
<dt><samp>mode</samp></dt>
<dd><p>Set display mode.
</p>
<p>Available values are:
</p><dl compact="compact">
<dt>‘<samp>point</samp>’</dt>
<dd><p>Draw a point for each sample.
</p>
</dd>
<dt>‘<samp>line</samp>’</dt>
<dd><p>Draw a vertical line for each sample.
</p>
</dd>
<dt>‘<samp>p2p</samp>’</dt>
<dd><p>Draw a point for each sample and a line between them.
</p>
</dd>
<dt>‘<samp>cline</samp>’</dt>
<dd><p>Draw a centered vertical line for each sample.
</p></dd>
</dl>
<p>Default value is <code>point</code>.
</p>
</dd>
<dt><samp>n</samp></dt>
<dd><p>Set the number of samples which are printed on the same column. A
larger value will decrease the frame rate. Must be a positive
integer. This option can be set only if the value for <var>rate</var>
is not explicitly specified.
</p>
</dd>
<dt><samp>rate, r</samp></dt>
<dd><p>Set the (approximate) output frame rate. This is done by setting the
option <var>n</var>. Default value is "25".
</p>
</dd>
<dt><samp>split_channels</samp></dt>
<dd><p>Set if channels should be drawn separately or overlap. Default value is 0.
</p>
</dd>
</dl>
<a name="Examples-118"></a>
<h4 class="subsection">40.15.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-118" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-118" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Output the input file audio and the corresponding video representation
at the same time:
<div class="example">
<pre class="example">amovie=a.mp3,asplit[out0],showwaves[out1]
</pre></div>
</li><li> Create a synthetic signal and show it with showwaves, forcing a
frame rate of 30 frames per second:
<div class="example">
<pre class="example">aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
</pre></div>
</li></ul>
<a name="showwavespic"></a>
<h3 class="section">40.16 showwavespic<span class="pull-right"><a class="anchor hidden-xs" href="#showwavespic" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-showwavespic" aria-hidden="true">TOC</a></span></h3>
<p>Convert input audio to a single video frame, representing the samples waves.
</p>
<p>The filter accepts the following options:
</p>
<dl compact="compact">
<dt><samp>size, s</samp></dt>
<dd><p>Specify the video size for the output. For the syntax of this option, check the
<a href="ffmpeg-utils.html#video-size-syntax">(ffmpeg-utils)"Video size" section in the ffmpeg-utils manual</a>.
Default value is <code>600x240</code>.
</p>
</dd>
<dt><samp>split_channels</samp></dt>
<dd><p>Set if channels should be drawn separately or overlap. Default value is 0.
</p></dd>
</dl>
<a name="Examples-119"></a>
<h4 class="subsection">40.16.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-119" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-119" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Extract a channel split representation of the wave form of a whole audio track
in a 1024x800 picture using <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
</pre></div>
</li></ul>
<a name="split_002c-asplit"></a>
<h3 class="section">40.17 split, asplit<span class="pull-right"><a class="anchor hidden-xs" href="#split_002c-asplit" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-split_002c-asplit" aria-hidden="true">TOC</a></span></h3>
<p>Split input into several identical outputs.
</p>
<p><code>asplit</code> works with audio input, <code>split</code> with video.
</p>
<p>The filter accepts a single parameter which specifies the number of outputs. If
unspecified, it defaults to 2.
</p>
<a name="Examples-120"></a>
<h4 class="subsection">40.17.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-120" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-120" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Create two separate outputs from the same input:
<div class="example">
<pre class="example">[in] split [out0][out1]
</pre></div>
</li><li> To create 3 or more outputs, you need to specify the number of
outputs, like in:
<div class="example">
<pre class="example">[in] asplit=3 [out0][out1][out2]
</pre></div>
</li><li> Create two separate outputs from the same input, one cropped and
one padded:
<div class="example">
<pre class="example">[in] split [splitout1][splitout2];
[splitout1] crop=100:100:0:0 [cropout];
[splitout2] pad=200:200:100:100 [padout];
</pre></div>
</li><li> Create 5 copies of the input audio with <code>ffmpeg</code>:
<div class="example">
<pre class="example">ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
</pre></div>
</li></ul>
<a name="zmq_002c-azmq"></a>
<h3 class="section">40.18 zmq, azmq<span class="pull-right"><a class="anchor hidden-xs" href="#zmq_002c-azmq" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-zmq_002c-azmq" aria-hidden="true">TOC</a></span></h3>
<p>Receive commands sent through a libzmq client, and forward them to
filters in the filtergraph.
</p>
<p><code>zmq</code> and <code>azmq</code> work as a pass-through filters. <code>zmq</code>
must be inserted between two video filters, <code>azmq</code> between two
audio filters.
</p>
<p>To enable these filters you need to install the libzmq library and
headers and configure FFmpeg with <code>--enable-libzmq</code>.
</p>
<p>For more information about libzmq see:
<a href="http://www.zeromq.org/">http://www.zeromq.org/</a>
</p>
<p>The <code>zmq</code> and <code>azmq</code> filters work as a libzmq server, which
receives messages sent through a network interface defined by the
<samp>bind_address</samp> option.
</p>
<p>The received message must be in the form:
</p><div class="example">
<pre class="example"><var>TARGET</var> <var>COMMAND</var> [<var>ARG</var>]
</pre></div>
<p><var>TARGET</var> specifies the target of the command, usually the name of
the filter class or a specific filter instance name.
</p>
<p><var>COMMAND</var> specifies the name of the command for the target filter.
</p>
<p><var>ARG</var> is optional and specifies the optional argument list for the
given <var>COMMAND</var>.
</p>
<p>Upon reception, the message is processed and the corresponding command
is injected into the filtergraph. Depending on the result, the filter
will send a reply to the client, adopting the format:
</p><div class="example">
<pre class="example"><var>ERROR_CODE</var> <var>ERROR_REASON</var>
<var>MESSAGE</var>
</pre></div>
<p><var>MESSAGE</var> is optional.
</p>
<a name="Examples-121"></a>
<h4 class="subsection">40.18.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-121" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-121" aria-hidden="true">TOC</a></span></h4>
<p>Look at <samp>tools/zmqsend</samp> for an example of a zmq client which can
be used to send commands processed by these filters.
</p>
<p>Consider the following filtergraph generated by <code>ffplay</code>
</p><div class="example">
<pre class="example">ffplay -dumpgraph 1 -f lavfi "
color=s=100x100:c=red [l];
color=s=100x100:c=blue [r];
nullsrc=s=200x100, zmq [bg];
[bg][l] overlay [bg+l];
[bg+l][r] overlay=x=100 "
</pre></div>
<p>To change the color of the left side of the video, the following
command can be used:
</p><div class="example">
<pre class="example">echo Parsed_color_0 c yellow | tools/zmqsend
</pre></div>
<p>To change the right side:
</p><div class="example">
<pre class="example">echo Parsed_color_1 c pink | tools/zmqsend
</pre></div>
<a name="Multimedia-Sources"></a>
<h2 class="chapter">41 Multimedia Sources<span class="pull-right"><a class="anchor hidden-xs" href="#Multimedia-Sources" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Multimedia-Sources" aria-hidden="true">TOC</a></span></h2>
<p>Below is a description of the currently available multimedia sources.
</p>
<a name="amovie"></a>
<h3 class="section">41.1 amovie<span class="pull-right"><a class="anchor hidden-xs" href="#amovie" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-amovie" aria-hidden="true">TOC</a></span></h3>
<p>This is the same as <a href="#movie">movie</a> source, except it selects an audio
stream by default.
</p>
<a name="movie"></a><a name="movie-1"></a>
<h3 class="section">41.2 movie<span class="pull-right"><a class="anchor hidden-xs" href="#movie-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-movie-1" aria-hidden="true">TOC</a></span></h3>
<p>Read audio and/or video stream(s) from a movie container.
</p>
<p>It accepts the following parameters:
</p>
<dl compact="compact">
<dt><samp>filename</samp></dt>
<dd><p>The name of the resource to read (not necessarily a file; it can also be a
device or a stream accessed through some protocol).
</p>
</dd>
<dt><samp>format_name, f</samp></dt>
<dd><p>Specifies the format assumed for the movie to read, and can be either
the name of a container or an input device. If not specified, the
format is guessed from <var>movie_name</var> or by probing.
</p>
</dd>
<dt><samp>seek_point, sp</samp></dt>
<dd><p>Specifies the seek point in seconds. The frames will be output
starting from this seek point. The parameter is evaluated with
<code>av_strtod</code>, so the numerical value may be suffixed by an IS
postfix. The default value is "0".
</p>
</dd>
<dt><samp>streams, s</samp></dt>
<dd><p>Specifies the streams to read. Several streams can be specified,
separated by "+". The source will then have as many outputs, in the
same order. The syntax is explained in the “Stream specifiers”
section in the ffmpeg manual. Two special names, "dv" and "da" specify
respectively the default (best suited) video and audio stream. Default
is "dv", or "da" if the filter is called as "amovie".
</p>
</dd>
<dt><samp>stream_index, si</samp></dt>
<dd><p>Specifies the index of the video stream to read. If the value is -1,
the most suitable video stream will be automatically selected. The default
value is "-1". Deprecated. If the filter is called "amovie", it will select
audio instead of video.
</p>
</dd>
<dt><samp>loop</samp></dt>
<dd><p>Specifies how many times to read the stream in sequence.
If the value is less than 1, the stream will be read again and again.
Default value is "1".
</p>
<p>Note that when the movie is looped the source timestamps are not
changed, so it will generate non monotonically increasing timestamps.
</p></dd>
</dl>
<p>It allows overlaying a second video on top of the main input of
a filtergraph, as shown in this graph:
</p><div class="example">
<pre class="example">input -----------> deltapts0 --> overlay --> output
^
|
movie --> scale--> deltapts1 -------+
</pre></div>
<a name="Examples-122"></a>
<h4 class="subsection">41.2.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-122" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-122" aria-hidden="true">TOC</a></span></h4>
<ul>
<li> Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
on top of the input labelled "in":
<div class="example">
<pre class="example">movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
</pre></div>
</li><li> Read from a video4linux2 device, and overlay it on top of the input
labelled "in":
<div class="example">
<pre class="example">movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
</pre></div>
</li><li> Read the first video stream and the audio stream with id 0x81 from
dvd.vob; the video is connected to the pad named "video" and the audio is
connected to the pad named "audio":
<div class="example">
<pre class="example">movie=dvd.vob:s=v:0+#0x81 [video] [audio]
</pre></div>
</li></ul>
<a name="See-Also"></a>
<h2 class="chapter">42 See Also<span class="pull-right"><a class="anchor hidden-xs" href="#See-Also" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-See-Also" aria-hidden="true">TOC</a></span></h2>
<p><a href="ffserver.html">ffserver</a>,
the <samp>doc/ffserver.conf</samp> example,
<a href="ffmpeg.html">ffmpeg</a>, <a href="ffplay.html">ffplay</a>, <a href="ffprobe.html">ffprobe</a>,
<a href="ffmpeg-utils.html">ffmpeg-utils</a>,
<a href="ffmpeg-scaler.html">ffmpeg-scaler</a>,
<a href="ffmpeg-resampler.html">ffmpeg-resampler</a>,
<a href="ffmpeg-codecs.html">ffmpeg-codecs</a>,
<a href="ffmpeg-bitstream-filters.html">ffmpeg-bitstream-filters</a>,
<a href="ffmpeg-formats.html">ffmpeg-formats</a>,
<a href="ffmpeg-devices.html">ffmpeg-devices</a>,
<a href="ffmpeg-protocols.html">ffmpeg-protocols</a>,
<a href="ffmpeg-filters.html">ffmpeg-filters</a>
</p>
<a name="Authors"></a>
<h2 class="chapter">43 Authors<span class="pull-right"><a class="anchor hidden-xs" href="#Authors" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Authors" aria-hidden="true">TOC</a></span></h2>
<p>The FFmpeg developers.
</p>
<p>For details about the authorship, see the Git history of the project
(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
<code>git log</code> in the FFmpeg source directory, or browsing the
online repository at <a href="http://source.ffmpeg.org">http://source.ffmpeg.org</a>.
</p>
<p>Maintainers for the specific components are listed in the file
<samp>MAINTAINERS</samp> in the source code tree.
</p>
<p style="font-size: small;">
This document was generated using <a href="http://www.gnu.org/software/texinfo/"><em>makeinfo</em></a>.
</p>
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