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<a href="#gst-plugins-good-plugins-level.synopsis" class="shortcut">Top</a>
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<a href="#gst-plugins-good-plugins-level.description" class="shortcut">Description</a>
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<a href="#gst-plugins-good-plugins-level.object-hierarchy" class="shortcut">Object Hierarchy</a>
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<a href="#gst-plugins-good-plugins-level.properties" class="shortcut">Properties</a>
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<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 valign="top" align="right"></td>
</tr></table></div>
<div class="refsynopsisdiv">
<a name="gst-plugins-good-plugins-level.synopsis"></a><h2>Synopsis</h2>
<a name="GstLevel"></a><pre class="synopsis">struct <a class="link" href="gst-plugins-good-plugins-level.html#GstLevel-struct" title="struct GstLevel">GstLevel</a>;
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="synopsis">
<a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a>
+----<a href="/usr/share/gtk-doc/html/gstreamer-0.10/GstObject.html">GstObject</a>
+----<a href="/usr/share/gtk-doc/html/gstreamer-0.10/GstElement.html">GstElement</a>
+----<a href="/usr/share/gtk-doc/html/gstreamer-libs-0.10/GstBaseTransform.html">GstBaseTransform</a>
+----GstLevel
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.properties"></a><h2>Properties</h2>
<pre class="synopsis">
"<a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--interval" title='The "interval" property'>interval</a>" <span class="type">guint64</span> : Read / Write
"<a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--message" title='The "message" property'>message</a>" <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> : Read / Write
"<a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-falloff" title='The "peak-falloff" property'>peak-falloff</a>" <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> : Read / Write
"<a class="link" href="gst-plugins-good-plugins-level.html#GstLevel--peak-ttl" title='The "peak-ttl" property'>peak-ttl</a>" <span class="type">guint64</span> : Read / Write
</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
<code class="classname">"level"</code>:
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" type="disc">
<li class="listitem"><p>
<a href="/usr/share/gtk-doc/html/gstreamer-0.10/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-0.10/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-0.10/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-0.10/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-0.10/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>
<span class="type">GstValueList</span> 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>
<span class="type">GstValueList</span> 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>
<span class="type">GstValueList</span> 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>
<p>
</p>
<p>
</p>
<div class="refsect2">
<a name="idm14464"></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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <string.h>
#include <math.h>
#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 *list;
const GValue *value;
gint i;
if (!gst_structure_get_clock_time (s, "endtime", &endtime))
g_warning ("Could not parse endtime");
/* we can get the number of channels as the length of any of the value
* lists */
list = gst_structure_get_value (s, "rms");
channels = gst_value_list_get_size (list);
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);
list = gst_structure_get_value (s, "rms");
value = gst_value_list_get_value (list, i);
rms_dB = g_value_get_double (value);
list = gst_structure_get_value (s, "peak");
value = gst_value_list_get_value (list, i);
peak_dB = g_value_get_double (value);
list = gst_structure_get_value (s, "decay");
value = gst_value_list_get_value (list, 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-int,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), "message", 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>
<p>
</p>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="refsect2">
<a name="idp9673152"></a><h3>Element Information</h3>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<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="idp8914288"></a><h3>Element Pads</h3>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<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-int, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], endianness=(int)1234, width=(int){ 8, 16, 32 }, depth=(int){ 8, 16, 32 }, signed=(boolean)true</td>
</tr>
<tr>
<td><p><span class="term"></span></p></td>
<td> audio/x-raw-float, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], endianness=(int)1234, width=(int){ 32, 64 }</td>
</tr>
</tbody>
</table></div>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<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-int, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], endianness=(int)1234, width=(int){ 8, 16, 32 }, depth=(int){ 8, 16, 32 }, signed=(boolean)true</td>
</tr>
<tr>
<td><p><span class="term"></span></p></td>
<td> audio/x-raw-float, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], endianness=(int)1234, width=(int){ 32, 64 }</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<p>
</p>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-level.details"></a><h2>Details</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> : Read / Write</pre>
<p>Interval of time between message posts (in nanoseconds).</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> : Read / Write</pre>
<p>Post a level message for each passed interval.</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> : Read / Write</pre>
<p>Decay rate of decay peak after TTL (in dB/sec).</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> : Read / Write</pre>
<p>Time To Live of decay peak before it falls back (in nanoseconds).</p>
<p>Default value: 300000000</p>
</div>
</div>
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