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<h1 class="settitle">avserver Documentation</h1>
<a name="SEC_Contents"></a>
<h1>Table of Contents</h1>
<div class="contents">
<ul class="toc">
<li><a name="toc-Synopsys" href="#Synopsys">1. Synopsys</a></li>
<li><a name="toc-Description" href="#Description">2. Description</a>
<ul class="toc">
<li><a name="toc-How-does-it-work_003f" href="#How-does-it-work_003f">2.1 How does it work?</a></li>
<li><a name="toc-Status-stream" href="#Status-stream">2.2 Status stream</a></li>
<li><a name="toc-What-can-this-do_003f" href="#What-can-this-do_003f">2.3 What can this do?</a></li>
<li><a name="toc-What-do-I-need_003f" href="#What-do-I-need_003f">2.4 What do I need?</a></li>
<li><a name="toc-How-do-I-make-it-work_003f" href="#How-do-I-make-it-work_003f">2.5 How do I make it work?</a></li>
<li><a name="toc-What-happens-next_003f" href="#What-happens-next_003f">2.6 What happens next?</a></li>
<li><a name="toc-Troubleshooting" href="#Troubleshooting">2.7 Troubleshooting</a>
<ul class="toc">
<li><a name="toc-I-don_0027t-hear-any-audio_002c-but-video-is-fine_002e" href="#I-don_0027t-hear-any-audio_002c-but-video-is-fine_002e">2.7.1 I don’t hear any audio, but video is fine.</a></li>
<li><a name="toc-The-audio-and-video-lose-sync-after-a-while_002e" href="#The-audio-and-video-lose-sync-after-a-while_002e">2.7.2 The audio and video lose sync after a while.</a></li>
<li><a name="toc-After-a-long-while_002c-the-video-update-rate-goes-way-down-in-WMP_002e" href="#After-a-long-while_002c-the-video-update-rate-goes-way-down-in-WMP_002e">2.7.3 After a long while, the video update rate goes way down in WMP.</a></li>
<li><a name="toc-WMP-6_002e4-behaves-differently-to-WMP-7_002e" href="#WMP-6_002e4-behaves-differently-to-WMP-7_002e">2.7.4 WMP 6.4 behaves differently to WMP 7.</a></li>
</ul></li>
<li><a name="toc-What-else-can-it-do_003f" href="#What-else-can-it-do_003f">2.8 What else can it do?</a></li>
<li><a name="toc-Tips" href="#Tips">2.9 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">2.10 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">2.11 Does the <code>?date=</code> stuff work.</a></li>
</ul></li>
<li><a name="toc-Options" href="#Options">3. Options</a>
<ul class="toc">
<li><a name="toc-Stream-specifiers-1" href="#Stream-specifiers-1">3.1 Stream specifiers</a></li>
<li><a name="toc-Generic-options" href="#Generic-options">3.2 Generic options</a></li>
<li><a name="toc-AVOptions" href="#AVOptions">3.3 AVOptions</a></li>
<li><a name="toc-Main-options" href="#Main-options">3.4 Main options</a></li>
</ul>
</li>
</ul>
</div>
<a name="Synopsys"></a>
<h1 class="chapter"><a href="avserver.html#toc-Synopsys">1. Synopsys</a></h1>
<p>The generic syntax is:
</p>
<table><tr><td> </td><td><pre class="example">avserver [options]
</pre></td></tr></table>
<a name="Description"></a>
<h1 class="chapter"><a href="avserver.html#toc-Description">2. Description</a></h1>
<p>WARNING: avserver is unmaintained, largely broken and in need of a
complete rewrite. It probably won’t work for you. Use at your own
risk.
</p>
<p>avserver 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 in avserver.conf).
</p>
<p>avserver runs in daemon mode by default; that is, it puts itself in
the background and detaches from its TTY, unless it is launched in
debug mode or a NoDaemon option is specified in the configuration
file.
</p>
<p>This documentation covers only the streaming aspects of avserver /
avconv. All questions about parameters for avconv, codec questions,
etc. are not covered here. Read ‘<tt>avconv.html</tt>’ for more
information.
</p>
<a name="How-does-it-work_003f"></a>
<h2 class="section"><a href="avserver.html#toc-How-does-it-work_003f">2.1 How does it work?</a></h2>
<p>avserver receives prerecorded files or FFM streams from some avconv
instance as input, then streams them over RTP/RTSP/HTTP.
</p>
<p>An avserver instance will listen on some port as specified in the
configuration file. You can launch one or more instances of avconv and
send one or more FFM streams to the port where avserver is expecting
to receive them. Alternately, you can make avserver launch such avconv
instances at startup.
</p>
<p>Input streams are called feeds, and each one is specified by a <Feed>
section in the configuration file.
</p>
<p>For each feed you can have different output streams in various
formats, each one specified by a <Stream> section in the configuration
file.
</p>
<a name="Status-stream"></a>
<h2 class="section"><a href="avserver.html#toc-Status-stream">2.2 Status stream</a></h2>
<p>avserver 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><table><tr><td> </td><td><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></td></tr></table>
<p>then the server will post a page with the status information when
the special stream ‘<tt>status.html</tt>’ is requested.
</p>
<a name="What-can-this-do_003f"></a>
<h2 class="section"><a href="avserver.html#toc-What-can-this-do_003f">2.3 What can this do?</a></h2>
<p>When properly configured and running, you can capture video and audio in real
time from a suitable capture card, and stream it out over the Internet to
either Windows Media Player or RealAudio player (with some restrictions).
</p>
<p>It can also stream from files, though that is currently broken. Very often, a
web server can be used to serve up the files just as well.
</p>
<p>It can stream prerecorded video from .ffm files, though it is somewhat tricky
to make it work correctly.
</p>
<a name="What-do-I-need_003f"></a>
<h2 class="section"><a href="avserver.html#toc-What-do-I-need_003f">2.4 What do I need?</a></h2>
<p>I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV capture card. I’m
using stock Linux 2.4.17 with the stock drivers. [Actually that isn’t true,
I needed some special drivers for my motherboard-based sound card.]
</p>
<p>I understand that FreeBSD systems work just fine as well.
</p>
<a name="How-do-I-make-it-work_003f"></a>
<h2 class="section"><a href="avserver.html#toc-How-do-I-make-it-work_003f">2.5 How do I make it work?</a></h2>
<p>First, build the kit. It *really* helps to have installed LAME first. Then when
you run the avserver ./configure, make sure that you have the
<code>--enable-libmp3lame</code> flag turned on.
</p>
<p>LAME is important as it allows for streaming audio to Windows Media Player.
Don’t ask why the other audio types do not work.
</p>
<p>As a simple test, just run the following two command lines where INPUTFILE
is some file which you can decode with avconv:
</p>
<table><tr><td> </td><td><pre class="example">./avserver -f doc/avserver.conf &
./avconv -i INPUTFILE http://localhost:8090/feed1.ffm
</pre></td></tr></table>
<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>
<table><tr><td> </td><td><pre class="example"> http://<linuxbox>:8090/test.asf
</pre></td></tr></table>
<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>
<a name="What-happens-next_003f"></a>
<h2 class="section"><a href="avserver.html#toc-What-happens-next_003f">2.6 What happens next?</a></h2>
<p>You should edit the avserver.conf file to suit your needs (in terms of
frame rates etc). Then install avserver and avconv, write a script to start
them up, and off you go.
</p>
<a name="Troubleshooting"></a>
<h2 class="section"><a href="avserver.html#toc-Troubleshooting">2.7 Troubleshooting</a></h2>
<a name="I-don_0027t-hear-any-audio_002c-but-video-is-fine_002e"></a>
<h3 class="subsection"><a href="avserver.html#toc-I-don_0027t-hear-any-audio_002c-but-video-is-fine_002e">2.7.1 I don’t hear any audio, but video is fine.</a></h3>
<p>Maybe you didn’t install LAME, or got your ./configure statement wrong. Check
the avconv output to see if a line referring to MP3 is present. If not, then
your configuration was incorrect. If it is, then maybe your wiring is not
set up correctly. Maybe the sound card is not getting data from the right
input source. Maybe you have a really awful audio interface (like I do)
that only captures in stereo and also requires that one channel be flipped.
If you are one of these people, then export ’AUDIO_FLIP_LEFT=1’ before
starting avconv.
</p>
<a name="The-audio-and-video-lose-sync-after-a-while_002e"></a>
<h3 class="subsection"><a href="avserver.html#toc-The-audio-and-video-lose-sync-after-a-while_002e">2.7.2 The audio and video lose sync after a while.</a></h3>
<p>Yes, they do.
</p>
<a name="After-a-long-while_002c-the-video-update-rate-goes-way-down-in-WMP_002e"></a>
<h3 class="subsection"><a href="avserver.html#toc-After-a-long-while_002c-the-video-update-rate-goes-way-down-in-WMP_002e">2.7.3 After a long while, the video update rate goes way down in WMP.</a></h3>
<p>Yes, it does. Who knows why?
</p>
<a name="WMP-6_002e4-behaves-differently-to-WMP-7_002e"></a>
<h3 class="subsection"><a href="avserver.html#toc-WMP-6_002e4-behaves-differently-to-WMP-7_002e">2.7.4 WMP 6.4 behaves differently to WMP 7.</a></h3>
<p>Yes, it does. Any thoughts on this would be gratefully received. These
differences extend to embedding WMP into a web page. [There are two
object IDs that you can use: The old one, which does not play well, and
the new one, which does (both tested on the same system). However,
I suspect that the new one is not available unless you have installed WMP 7].
</p>
<a name="What-else-can-it-do_003f"></a>
<h2 class="section"><a href="avserver.html#toc-What-else-can-it-do_003f">2.8 What else can it do?</a></h2>
<p>You can replay video from .ffm files that was recorded earlier.
However, there are a number of caveats, including the fact that the
avserver parameters must match the original parameters used to record the
file. If they do not, then avserver 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
avserver.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>
<h2 class="section"><a href="avserver.html#toc-Tips">2.9 Tips</a></h2>
<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, avserver (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 avserver.conf that will
add the 15 second prebuffering on all requests that do not otherwise
specify a time. In addition, avserver will skip frames until a key_frame
is found. This further reduces the startup delay by not transferring data
that will be discarded.
</p>
<p>* You may want to adjust the MaxBandwidth in the avserver.conf to limit
the amount of bandwidth consumed by live streams.
</p>
<a name="Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f"></a>
<h2 class="section"><a href="avserver.html#toc-Why-does-the-_003fbuffer-_002f-Preroll-stop-working-after-a-time_003f">2.10 Why does the ?buffer / Preroll stop working after a time?</a></h2>
<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>
<h2 class="section"><a href="avserver.html#toc-Does-the-_003fdate_003d-stuff-work_002e">2.11 Does the <code>?date=</code> stuff work.</a></h2>
<p>Yes (subject to the limitation outlined above). Also note that whenever you
start avserver, 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>
<table><tr><td> </td><td><pre class="example">* YYYY-MM-DDTHH:MM:SS (localtime)
* YYYY-MM-DDTHH:MM:SSZ (UTC)
</pre></td></tr></table>
<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>
<h1 class="chapter"><a href="avserver.html#toc-Options">3. Options</a></h1>
<p>All the numerical options, if not specified otherwise, accept in input
a string representing a number, which may contain one of the
International System number postfixes, for example ’K’, ’M’, ’G’.
If ’i’ is appended after the postfix, powers of 2 are used instead of
powers of 10. The ’B’ postfix multiplies the value for 8, and can be
appended after another postfix or used alone. This allows using for
example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
</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
with "no" the option name, for example using "-nofoo" in the
command line will set to false the boolean option with name "foo".
</p>
<p><a name="Stream-specifiers"></a>
</p><a name="Stream-specifiers-1"></a>
<h2 class="section"><a href="avserver.html#toc-Stream-specifiers-1">3.1 Stream specifiers</a></h2>
<p>Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
are used to precisely specify which stream(s) does a given option belong 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> option contains
<code>a:1</code> stream specifer, 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 stream, the option is then 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: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
’d’ for data and ’t’ for attachments. If <var>stream_index</var> is given, then
matches stream number <var>stream_index</var> of this type. Otherwise 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 matches stream number <var>stream_index</var> in
program with id <var>program_id</var>. Otherwise matches all streams in this program.
</p></dd>
</dl>
<a name="Generic-options"></a>
<h2 class="section"><a href="avserver.html#toc-Generic-options">3.2 Generic options</a></h2>
<p>These options are shared amongst the av* tools.
</p>
<dl compact="compact">
<dt> ‘<samp>-L</samp>’</dt>
<dd><p>Show license.
</p>
</dd>
<dt> ‘<samp>-h, -?, -help, --help</samp>’</dt>
<dd><p>Show help.
</p>
</dd>
<dt> ‘<samp>-version</samp>’</dt>
<dd><p>Show version.
</p>
</dd>
<dt> ‘<samp>-formats</samp>’</dt>
<dd><p>Show available formats.
</p>
<p>The fields preceding the format names have the following meanings:
</p><dl compact="compact">
<dt> ‘<samp>D</samp>’</dt>
<dd><p>Decoding available
</p></dd>
<dt> ‘<samp>E</samp>’</dt>
<dd><p>Encoding available
</p></dd>
</dl>
</dd>
<dt> ‘<samp>-codecs</samp>’</dt>
<dd><p>Show available codecs.
</p>
<p>The fields preceding the codec names have the following meanings:
</p><dl compact="compact">
<dt> ‘<samp>D</samp>’</dt>
<dd><p>Decoding available
</p></dd>
<dt> ‘<samp>E</samp>’</dt>
<dd><p>Encoding available
</p></dd>
<dt> ‘<samp>V/A/S</samp>’</dt>
<dd><p>Video/audio/subtitle codec
</p></dd>
<dt> ‘<samp>S</samp>’</dt>
<dd><p>Codec supports slices
</p></dd>
<dt> ‘<samp>D</samp>’</dt>
<dd><p>Codec supports direct rendering
</p></dd>
<dt> ‘<samp>T</samp>’</dt>
<dd><p>Codec can handle input truncated at random locations instead of only at frame boundaries
</p></dd>
</dl>
</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>-loglevel <var>loglevel</var> | -v <var>loglevel</var></samp>’</dt>
<dd><p>Set the logging level used by the library.
<var>loglevel</var> is a number or a string containing one of the following values:
</p><dl compact="compact">
<dt> ‘<samp>quiet</samp>’</dt>
<dt> ‘<samp>panic</samp>’</dt>
<dt> ‘<samp>fatal</samp>’</dt>
<dt> ‘<samp>error</samp>’</dt>
<dt> ‘<samp>warning</samp>’</dt>
<dt> ‘<samp>info</samp>’</dt>
<dt> ‘<samp>verbose</samp>’</dt>
<dt> ‘<samp>debug</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 Libav version.
</p>
</dd>
</dl>
<a name="AVOptions"></a>
<h2 class="section"><a href="avserver.html#toc-AVOptions">3.3 AVOptions</a></h2>
<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><table><tr><td> </td><td><pre class="example">avconv -i input.flac -id3v2_version 3 out.mp3
</pre></td></tr></table>
<p>All codec AVOptions are obviously per-stream, so the chapter on stream
specifiers applies to them
</p>
<p>Note ‘<samp>-nooption</samp>’ syntax cannot be used for boolean AVOptions,
use ‘<samp>-option 0</samp>’/‘<samp>-option 1</samp>’.
</p>
<p>Note2 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>
<h2 class="section"><a href="avserver.html#toc-Main-options">3.4 Main options</a></h2>
<dl compact="compact">
<dt> ‘<samp>-f <var>configfile</var></samp>’</dt>
<dd><p>Use ‘<tt>configfile</tt>’ instead of ‘<tt>/etc/avserver.conf</tt>’.
</p></dd>
<dt> ‘<samp>-n</samp>’</dt>
<dd><p>Enable no-launch mode. This option disables all the Launch directives
within the various <Stream> sections. Since avserver will not launch
any avconv 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, directs log
messages to stdout and causes avserver to run in the foreground
rather than as a daemon.
</p></dd>
</dl>
<div id="footer">
<p>
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This document was generated by <em>Build Daemon user</em> on <em>March 22, 2012</em> using <a href="http://www.nongnu.org/texi2html/"><em>texi2html 1.82</em></a>.
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