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| <div class="refentry"> |
| <a name="gst-plugins-base-libs-gstaudiometa"></a><div class="titlepage"></div> |
| <div class="refnamediv"><table width="100%"><tr> |
| <td valign="top"> |
| <h2><span class="refentrytitle"><a name="gst-plugins-base-libs-gstaudiometa.top_of_page"></a>gstaudiometa</span></h2> |
| <p>gstaudiometa — Buffer metadata for audio downmix matrix handling</p> |
| </td> |
| <td class="gallery_image" valign="top" align="right"></td> |
| </tr></table></div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.functions"></a><h2>Functions</h2> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="150px" class="functions_return"> |
| <col class="functions_name"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="function_type"> |
| <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="returnvalue">GstAudioDownmixMeta</span></a> * |
| </td> |
| <td class="function_name"> |
| <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#gst-buffer-add-audio-downmix-meta" title="gst_buffer_add_audio_downmix_meta ()">gst_buffer_add_audio_downmix_meta</a> <span class="c_punctuation">()</span> |
| </td> |
| </tr> |
| <tr> |
| <td class="define_keyword">#define</td> |
| <td class="function_name"> |
| <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#gst-buffer-get-audio-downmix-meta" title="gst_buffer_get_audio_downmix_meta()">gst_buffer_get_audio_downmix_meta</a><span class="c_punctuation">()</span> |
| </td> |
| </tr> |
| <tr> |
| <td class="function_type"> |
| <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="returnvalue">GstAudioDownmixMeta</span></a> * |
| </td> |
| <td class="function_name"> |
| <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#gst-buffer-get-audio-downmix-meta-for-channels" title="gst_buffer_get_audio_downmix_meta_for_channels ()">gst_buffer_get_audio_downmix_meta_for_channels</a> <span class="c_punctuation">()</span> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.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-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta">GstAudioDownmixMeta</a></td> |
| </tr></tbody> |
| </table></div> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.includes"></a><h2>Includes</h2> |
| <pre class="synopsis">#include <gst/audio/gstaudiometa.h> |
| </pre> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.description"></a><h2>Description</h2> |
| <p><a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="type">GstAudioDownmixMeta</span></a> defines an audio downmix matrix to be send along with |
| audio buffers. These functions in this module help to create and attach the |
| meta as well as extracting it.</p> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.functions_details"></a><h2>Functions</h2> |
| <div class="refsect2"> |
| <a name="gst-buffer-add-audio-downmix-meta"></a><h3>gst_buffer_add_audio_downmix_meta ()</h3> |
| <pre class="programlisting"><a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="returnvalue">GstAudioDownmixMeta</span></a> * |
| gst_buffer_add_audio_downmix_meta (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBuffer.html"><span class="type">GstBuffer</span></a> *buffer</code></em>, |
| <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstaudiochannels.html#GstAudioChannelPosition" title="enum GstAudioChannelPosition"><span class="type">GstAudioChannelPosition</span></a> *from_position</code></em>, |
| <em class="parameter"><code><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> from_channels</code></em>, |
| <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstaudiochannels.html#GstAudioChannelPosition" title="enum GstAudioChannelPosition"><span class="type">GstAudioChannelPosition</span></a> *to_position</code></em>, |
| <em class="parameter"><code><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> to_channels</code></em>, |
| <em class="parameter"><code>const <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> **matrix</code></em>);</pre> |
| <p>Attaches <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="type">GstAudioDownmixMeta</span></a> metadata to <em class="parameter"><code>buffer</code></em> |
| with the given parameters.</p> |
| <p><em class="parameter"><code>matrix</code></em> |
| is an two-dimensional array of <em class="parameter"><code>to_channels</code></em> |
| times <em class="parameter"><code>from_channels</code></em> |
| |
| coefficients, i.e. the i-th output channels is constructed by multiplicating |
| the input channels with the coefficients in <em class="parameter"><code>matrix</code></em> |
| [i] and taking the sum |
| of the results.</p> |
| <div class="refsect3"> |
| <a name="id-1.2.6.4.7.2.6"></a><h4>Parameters</h4> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="150px" class="parameters_name"> |
| <col class="parameters_description"> |
| <col width="200px" class="parameters_annotations"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="parameter_name"><p>buffer</p></td> |
| <td class="parameter_description"><p>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBuffer.html"><span class="type">GstBuffer</span></a></p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>from_position</p></td> |
| <td class="parameter_description"><p> the channel positions |
| of the source. </p></td> |
| <td class="parameter_annotations"><span class="annotation">[<acronym title="Parameter points to an array of items."><span class="acronym">array</span></acronym> length=from_channels]</span></td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>from_channels</p></td> |
| <td class="parameter_description"><p>The number of channels of the source</p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>to_position</p></td> |
| <td class="parameter_description"><p> the channel positions of |
| the destination. </p></td> |
| <td class="parameter_annotations"><span class="annotation">[<acronym title="Parameter points to an array of items."><span class="acronym">array</span></acronym> length=to_channels]</span></td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>to_channels</p></td> |
| <td class="parameter_description"><p>The number of channels of the destination</p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>matrix</p></td> |
| <td class="parameter_description"><p>The matrix coefficients.</p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <div class="refsect3"> |
| <a name="id-1.2.6.4.7.2.7"></a><h4>Returns</h4> |
| <p> the <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="type">GstAudioDownmixMeta</span></a> on <em class="parameter"><code>buffer</code></em> |
| . </p> |
| <p><span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span></p> |
| </div> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="gst-buffer-get-audio-downmix-meta"></a><h3>gst_buffer_get_audio_downmix_meta()</h3> |
| <pre class="programlisting">#define gst_buffer_get_audio_downmix_meta(b) ((GstAudioDownmixMeta*)gst_buffer_get_meta((b),GST_AUDIO_DOWNMIX_META_INFO)) |
| </pre> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="gst-buffer-get-audio-downmix-meta-for-channels"></a><h3>gst_buffer_get_audio_downmix_meta_for_channels ()</h3> |
| <pre class="programlisting"><a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="returnvalue">GstAudioDownmixMeta</span></a> * |
| gst_buffer_get_audio_downmix_meta_for_channels |
| (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBuffer.html"><span class="type">GstBuffer</span></a> *buffer</code></em>, |
| <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstaudiochannels.html#GstAudioChannelPosition" title="enum GstAudioChannelPosition"><span class="type">GstAudioChannelPosition</span></a> *to_position</code></em>, |
| <em class="parameter"><code><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> to_channels</code></em>);</pre> |
| <p>Find the <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="type">GstAudioDownmixMeta</span></a> on <em class="parameter"><code>buffer</code></em> |
| for the given destination |
| channel positions.</p> |
| <div class="refsect3"> |
| <a name="id-1.2.6.4.7.4.5"></a><h4>Parameters</h4> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="150px" class="parameters_name"> |
| <col class="parameters_description"> |
| <col width="200px" class="parameters_annotations"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="parameter_name"><p>buffer</p></td> |
| <td class="parameter_description"><p>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBuffer.html"><span class="type">GstBuffer</span></a></p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>to_position</p></td> |
| <td class="parameter_description"><p> the channel positions of |
| the destination. </p></td> |
| <td class="parameter_annotations"><span class="annotation">[<acronym title="Parameter points to an array of items."><span class="acronym">array</span></acronym> length=to_channels]</span></td> |
| </tr> |
| <tr> |
| <td class="parameter_name"><p>to_channels</p></td> |
| <td class="parameter_description"><p>The number of channels of the destination</p></td> |
| <td class="parameter_annotations"> </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <div class="refsect3"> |
| <a name="id-1.2.6.4.7.4.6"></a><h4>Returns</h4> |
| <p> the <a class="link" href="gst-plugins-base-libs-gstaudiometa.html#GstAudioDownmixMeta" title="struct GstAudioDownmixMeta"><span class="type">GstAudioDownmixMeta</span></a> on <em class="parameter"><code>buffer</code></em> |
| . </p> |
| <p><span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span></p> |
| </div> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstaudiometa.other_details"></a><h2>Types and Values</h2> |
| <div class="refsect2"> |
| <a name="GstAudioDownmixMeta"></a><h3>struct GstAudioDownmixMeta</h3> |
| <pre class="programlisting">struct GstAudioDownmixMeta { |
| GstMeta meta; |
| |
| GstAudioChannelPosition *from_position; |
| GstAudioChannelPosition *to_position; |
| gint from_channels, to_channels; |
| gfloat **matrix; |
| }; |
| </pre> |
| <p>Extra buffer metadata describing audio downmixing matrix. This metadata is |
| attached to audio buffers and contains a matrix to downmix the buffer number |
| of channels to <em class="parameter"><code>channels</code></em> |
| .</p> |
| <p><em class="parameter"><code>matrix</code></em> |
| is an two-dimensional array of <em class="parameter"><code>to_channels</code></em> |
| times <em class="parameter"><code>from_channels</code></em> |
| |
| coefficients, i.e. the i-th output channels is constructed by multiplicating |
| the input channels with the coefficients in <em class="parameter"><code>matrix</code></em> |
| [i] and taking the sum |
| of the results.</p> |
| <div class="refsect3"> |
| <a name="id-1.2.6.4.8.2.6"></a><h4>Members</h4> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="300px" class="struct_members_name"> |
| <col class="struct_members_description"> |
| <col width="200px" class="struct_members_annotations"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="struct_member_name"><p><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstMeta.html#GstMeta"><span class="type">GstMeta</span></a> <em class="structfield"><code><a name="GstAudioDownmixMeta.meta"></a>meta</code></em>;</p></td> |
| <td class="struct_member_description"><p>parent <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstMeta.html#GstMeta"><span class="type">GstMeta</span></a></p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="struct_member_name"><p><a class="link" href="gst-plugins-base-libs-gstaudiochannels.html#GstAudioChannelPosition" title="enum GstAudioChannelPosition"><span class="type">GstAudioChannelPosition</span></a> *<em class="structfield"><code><a name="GstAudioDownmixMeta.from-position"></a>from_position</code></em>;</p></td> |
| <td class="struct_member_description"><p>the channel positions of the source</p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="struct_member_name"><p><a class="link" href="gst-plugins-base-libs-gstaudiochannels.html#GstAudioChannelPosition" title="enum GstAudioChannelPosition"><span class="type">GstAudioChannelPosition</span></a> *<em class="structfield"><code><a name="GstAudioDownmixMeta.to-position"></a>to_position</code></em>;</p></td> |
| <td class="struct_member_description"><p>the channel positions of the destination</p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="struct_member_name"><p><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> <em class="structfield"><code><a name="GstAudioDownmixMeta.from-channels"></a>from_channels</code></em>;</p></td> |
| <td class="struct_member_description"><p>the number of channels of the source</p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="struct_member_name"><p><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> <em class="structfield"><code><a name="GstAudioDownmixMeta.to-channels"></a>to_channels</code></em>;</p></td> |
| <td class="struct_member_description"><p>the number of channels of the destination</p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="struct_member_name"><p><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> **<em class="structfield"><code><a name="GstAudioDownmixMeta.matrix"></a>matrix</code></em>;</p></td> |
| <td class="struct_member_description"><p>the matrix coefficients.</p></td> |
| <td class="struct_member_annotations"> </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| </div> |
| </div> |
| </div> |
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