/usr/share/gtk-doc/html/gst-plugins-good-plugins-1.0/gst-plugins-good-plugins-level.html is in gstreamer1.0-plugins-good-doc 1.2.4-1~ubuntu1.4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>GStreamer Good Plugins 1.0 Plugins Reference Manual: level</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
<link rel="home" href="index.html" title="GStreamer Good Plugins 1.0 Plugins Reference Manual">
<link rel="up" href="ch01.html" title="gst-plugins-good Elements">
<link rel="prev" href="gst-plugins-good-plugins-jpegenc.html" title="jpegenc">
<link rel="next" href="gst-plugins-good-plugins-matroskamux.html" title="matroskamux">
<meta name="generator" content="GTK-Doc V1.20 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="10"><tr valign="middle">
<td width="100%" align="left" class="shortcuts">
<a href="#" class="shortcut">Top</a><span id="nav_description"> <span class="dim">|</span>
<a href="#gst-plugins-good-plugins-level.description" class="shortcut">Description</a></span><span id="nav_hierarchy"> <span class="dim">|</span>
<a href="#gst-plugins-good-plugins-level.object-hierarchy" class="shortcut">Object Hierarchy</a></span><span id="nav_properties"> <span class="dim">|</span>
<a href="#gst-plugins-good-plugins-level.properties" class="shortcut">Properties</a></span>
</td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
<td><a accesskey="u" href="ch01.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
<td><a accesskey="p" href="gst-plugins-good-plugins-jpegenc.html"><img src="left.png" width="16" height="16" border="0" alt="Prev"></a></td>
<td><a accesskey="n" href="gst-plugins-good-plugins-matroskamux.html"><img src="right.png" width="16" height="16" border="0" alt="Next"></a></td>
</tr></table>
<div class="refentry">
<a name="gst-plugins-good-plugins-level"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-level.top_of_page"></a>level</span></h2>
<p>level — RMS/Peak/Decaying Peak Level messager for audio/raw</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.properties"></a><h2>Properties</h2>
<div class="informaltable"><table border="0">
<colgroup>
<col width="150px" class="properties_type">
<col width="300px" class="properties_name">
<col width="200px" class="properties_flags">
</colgroup>
<tbody>
<tr>
<td class="property_type"><span class="type">guint64</span></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--interval" title="The “interval” property">interval</a></td>
<td class="property_flags">Read / Write</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--message" title="The “message” property">message</a></td>
<td class="property_flags">Read / Write</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-falloff" title="The “peak-falloff” property">peak-falloff</a></td>
<td class="property_flags">Read / Write</td>
</tr>
<tr>
<td class="property_type"><span class="type">guint64</span></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-ttl" title="The “peak-ttl” property">peak-ttl</a></td>
<td class="property_flags">Read / Write</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--post-messages" title="The “post-messages” property">post-messages</a></td>
<td class="property_flags">Read / Write</td>
</tr>
</tbody>
</table></div>
</div>
<a name="GstLevel"></a><div class="refsect1">
<a name="gst-plugins-good-plugins-level.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-good-plugins-level.html#GstLevel-struct" title="struct GstLevel">GstLevel</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen"> <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GInitiallyUnowned">GInitiallyUnowned</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstObject.html">GstObject</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstElement.html">GstElement</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gstreamer-libs-1.0/GstBaseTransform.html">GstBaseTransform</a>
<span class="lineart">╰──</span> GstLevel
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.description"></a><h2>Description</h2>
<p>Level analyses incoming audio buffers and, if the <a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--message" title="The “message” property"><span class="type">“message”</span></a> property
is <a href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#TRUE:CAPS"><span class="type">TRUE</span></a>, generates an element message named</p>
<code class="classname">"level"</code>:
<p>after each interval of time given by the <a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--interval" title="The “interval” property"><span class="type">“interval”</span></a> property.
The message's structure contains these fields:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
<code class="classname">"timestamp"</code>:
the timestamp of the buffer that triggered the message.
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
<code class="classname">"stream-time"</code>:
the stream time of the buffer.
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
<code class="classname">"running-time"</code>:
the running_time of the buffer.
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
<code class="classname">"duration"</code>:
the duration of the buffer.
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
<code class="classname">"endtime"</code>:
the end time of the buffer that triggered the message as stream time (this
is deprecated, as it can be calculated from stream-time + duration)
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gobject/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a> of <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>
<code class="classname">"peak"</code>:
the peak power level in dB for each channel
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gobject/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a> of <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>
<code class="classname">"decay"</code>:
the decaying peak power level in dB for each channel
the decaying peak level follows the peak level, but starts dropping
if no new peak is reached after the time given by
the <a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-ttl" title="The “peak-ttl” property">the time to live</a>.
When the decaying peak level drops, it does so at the decay rate
as specified by the
<a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-falloff" title="The “peak-falloff” property">the peak falloff rate</a>.
</p></li>
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gobject/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a> of <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>
<code class="classname">"rms"</code>:
the Root Mean Square (or average power) level in dB for each channel
</p></li>
</ul></div>
<div class="refsect2">
<a name="id-1.2.74.7.6"></a><h3>Example application</h3>
<div class="informalexample"><pre class="programlisting">
/* GStreamer
* Copyright (C) 2000,2001,2002,2003,2005
* Thomas Vander Stichele <thomas at apestaart dot org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <math.h>
#define GLIB_DISABLE_DEPRECATION_WARNINGS
#include <gst/gst.h>
static gboolean
message_handler (GstBus * bus, GstMessage * message, gpointer data)
{
if (message->type == GST_MESSAGE_ELEMENT) {
const GstStructure *s = gst_message_get_structure (message);
const gchar *name = gst_structure_get_name (s);
if (strcmp (name, "level") == 0) {
gint channels;
GstClockTime endtime;
gdouble rms_dB, peak_dB, decay_dB;
gdouble rms;
const GValue *array_val;
const GValue *value;
GValueArray *rms_arr, *peak_arr, *decay_arr;
gint i;
if (!gst_structure_get_clock_time (s, "endtime", &endtime))
g_warning ("Could not parse endtime");
/* the values are packed into GValueArrays with the value per channel */
array_val = gst_structure_get_value (s, "rms");
rms_arr = (GValueArray *) g_value_get_boxed (array_val);
array_val = gst_structure_get_value (s, "peak");
peak_arr = (GValueArray *) g_value_get_boxed (array_val);
array_val = gst_structure_get_value (s, "decay");
decay_arr = (GValueArray *) g_value_get_boxed (array_val);
/* we can get the number of channels as the length of any of the value
* arrays */
channels = rms_arr->n_values;
g_print ("endtime: %" GST_TIME_FORMAT ", channels: %d\n",
GST_TIME_ARGS (endtime), channels);
for (i = 0; i < channels; ++i) {
g_print ("channel %d\n", i);
value = g_value_array_get_nth (rms_arr, i);
rms_dB = g_value_get_double (value);
value = g_value_array_get_nth (peak_arr, i);
peak_dB = g_value_get_double (value);
value = g_value_array_get_nth (decay_arr, i);
decay_dB = g_value_get_double (value);
g_print (" RMS: %f dB, peak: %f dB, decay: %f dB\n",
rms_dB, peak_dB, decay_dB);
/* converting from dB to normal gives us a value between 0.0 and 1.0 */
rms = pow (10, rms_dB / 20);
g_print (" normalized rms value: %f\n", rms);
}
}
}
/* we handled the message we want, and ignored the ones we didn't want.
* so the core can unref the message for us */
return TRUE;
}
int
main (int argc, char *argv[])
{
GstElement *audiotestsrc, *audioconvert, *level, *fakesink;
GstElement *pipeline;
GstCaps *caps;
GstBus *bus;
guint watch_id;
GMainLoop *loop;
gst_init (&argc, &argv);
caps = gst_caps_from_string ("audio/x-raw,channels=2");
pipeline = gst_pipeline_new (NULL);
g_assert (pipeline);
audiotestsrc = gst_element_factory_make ("audiotestsrc", NULL);
g_assert (audiotestsrc);
audioconvert = gst_element_factory_make ("audioconvert", NULL);
g_assert (audioconvert);
level = gst_element_factory_make ("level", NULL);
g_assert (level);
fakesink = gst_element_factory_make ("fakesink", NULL);
g_assert (fakesink);
gst_bin_add_many (GST_BIN (pipeline), audiotestsrc, audioconvert, level,
fakesink, NULL);
if (!gst_element_link (audiotestsrc, audioconvert))
g_error ("Failed to link audiotestsrc and audioconvert");
if (!gst_element_link_filtered (audioconvert, level, caps))
g_error ("Failed to link audioconvert and level");
if (!gst_element_link (level, fakesink))
g_error ("Failed to link level and fakesink");
/* make sure we'll get messages */
g_object_set (G_OBJECT (level), "post-messages", TRUE, NULL);
/* run synced and not as fast as we can */
g_object_set (G_OBJECT (fakesink), "sync", TRUE, NULL);
bus = gst_element_get_bus (pipeline);
watch_id = gst_bus_add_watch (bus, message_handler, NULL);
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* we need to run a GLib main loop to get the messages */
loop = g_main_loop_new (NULL, FALSE);
g_main_loop_run (loop);
g_source_remove (watch_id);
g_main_loop_unref (loop);
return 0;
}
</pre></div>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="refsect2">
<a name="id-1.2.74.7.7.1"></a><h3>Element Information</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">plugin</span></p></td>
<td>
<a class="link" href="gst-plugins-good-plugins-plugin-level.html#plugin-level">level</a>
</td>
</tr>
<tr>
<td><p><span class="term">author</span></p></td>
<td>Thomas Vander Stichele <thomas at apestaart dot org></td>
</tr>
<tr>
<td><p><span class="term">class</span></p></td>
<td>Filter/Analyzer/Audio</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="id-1.2.74.7.7.2"></a><h3>Element Pads</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>audio/x-raw, format=(string){ S8, S16LE, S32LE, F32LE, F64LE }, layout=(string)interleaved, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]</td>
</tr>
</tbody>
</table></div>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>src</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>source</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>audio/x-raw, format=(string){ S8, S16LE, S32LE, F32LE, F64LE }, layout=(string)interleaved, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<p>
</p>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.functions_details"></a><h2>Functions</h2>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstLevel-struct"></a><h3>struct GstLevel</h3>
<pre class="programlisting">struct GstLevel;</pre>
<p>Opaque data structure.</p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.property-details"></a><h2>Property Details</h2>
<div class="refsect2">
<a name="GstLevel--interval"></a><h3>The <code class="literal">“interval”</code> property</h3>
<pre class="programlisting"> “interval” <span class="type">guint64</span></pre>
<p>Interval of time between message posts (in nanoseconds).</p>
<p>Flags: Read / Write</p>
<p>Allowed values: >= 1</p>
<p>Default value: 100000000</p>
</div>
<hr>
<div class="refsect2">
<a name="GstLevel--message"></a><h3>The <code class="literal">“message”</code> property</h3>
<pre class="programlisting"> “message” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></pre>
<p>Post a 'level' message for each passed interval (deprecated).</p>
<p>Flags: Read / Write</p>
<p>Default value: TRUE</p>
</div>
<hr>
<div class="refsect2">
<a name="GstLevel--peak-falloff"></a><h3>The <code class="literal">“peak-falloff”</code> property</h3>
<pre class="programlisting"> “peak-falloff” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a></pre>
<p>Decay rate of decay peak after TTL (in dB/sec).</p>
<p>Flags: Read / Write</p>
<p>Allowed values: >= 0</p>
<p>Default value: 10</p>
</div>
<hr>
<div class="refsect2">
<a name="GstLevel--peak-ttl"></a><h3>The <code class="literal">“peak-ttl”</code> property</h3>
<pre class="programlisting"> “peak-ttl” <span class="type">guint64</span></pre>
<p>Time To Live of decay peak before it falls back (in nanoseconds).</p>
<p>Flags: Read / Write</p>
<p>Default value: 300000000</p>
</div>
<hr>
<div class="refsect2">
<a name="GstLevel--post-messages"></a><h3>The <code class="literal">“post-messages”</code> property</h3>
<pre class="programlisting"> “post-messages” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></pre>
<p>Post messages on the bus with level information.</p>
<div class="warning">
<p><code class="literal">GstLevel:post-messages</code> is deprecated and should not be used in newly-written code.</p>
<p>use the <a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--post-messages" title="The “post-messages” property"><span class="type">“post-messages”</span></a> property</p>
</div>
<p>Flags: Read / Write</p>
<p>Default value: TRUE</p>
<p class="since">Since 1.1.0</p>
</div>
</div>
</div>
<div class="footer">
<hr>
Generated by GTK-Doc V1.20</div>
</body>
</html>
|