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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<a href="#GstAggregator.description" class="shortcut">Description</a></span><span id="nav_hierarchy"> <span class="dim">|</span>
<a href="#GstAggregator.object-hierarchy" class="shortcut">Object Hierarchy</a></span>
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<div class="refentry">
<a name="GstAggregator"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="GstAggregator.top_of_page"></a>GstAggregator</span></h2>
<p>GstAggregator — manages a set of pads with the purpose of
aggregating their buffers.</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="GstAggregator.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 href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>
</td>
<td class="function_name">
<a class="link" href="GstAggregator.html#gst-aggregator-finish-buffer" title="gst_aggregator_finish_buffer ()">gst_aggregator_finish_buffer</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="GstAggregator.html#gst-aggregator-set-src-caps" title="gst_aggregator_set_src_caps ()">gst_aggregator_set_src_caps</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
</td>
<td class="function_name">
<a class="link" href="GstAggregator.html#gst-aggregator-iterate-sinkpads" title="gst_aggregator_iterate_sinkpads ()">gst_aggregator_iterate_sinkpads</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="GstAggregator.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="GstAggregator.html#GstAggregator-struct" title="struct GstAggregator">GstAggregator</a></td>
</tr>
<tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="GstAggregator.html#GstAggregatorClass" title="struct GstAggregatorClass">GstAggregatorClass</a></td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="GstAggregator.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen"> <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
<span class="lineart">╰──</span> <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GInitiallyUnowned">GInitiallyUnowned</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a>
<span class="lineart">╰──</span> GstAggregator
<span class="lineart">╰──</span> <a class="link" href="GstVideoAggregator.html" title="GstVideoAggregator">GstVideoAggregator</a>
</pre>
</div>
<div class="refsect1">
<a name="GstAggregator.description"></a><h2>Description</h2>
<p>Manages a set of pads with the purpose of aggregating their buffers.
Control is given to the subclass when all pads have data.</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>
Base class for mixers and muxers. Implementers should at least implement
the <code class="function">aggregate()</code> vmethod.
</p></li>
<li class="listitem"><p>
When data is queued on all pads, tha aggregate vmethod is called.
</p></li>
<li class="listitem"><p>
One can peek at the data on any given GstAggregatorPad with the
<a class="link" href="GstAggregatorPad.html#gst-aggregator-pad-get-buffer" title="gst_aggregator_pad_get_buffer ()"><code class="function">gst_aggregator_pad_get_buffer()</code></a> method, and take ownership of it
with the <a class="link" href="GstAggregatorPad.html#gst-aggregator-pad-steal-buffer" title="gst_aggregator_pad_steal_buffer ()"><code class="function">gst_aggregator_pad_steal_buffer()</code></a> method. When a buffer
has been taken with <code class="function">steal_buffer()</code>, a new buffer can be queued
on that pad.
</p></li>
<li class="listitem"><p>
If the subclass wishes to push a buffer downstream in its aggregate
implementation, it should do so through the
<a class="link" href="GstAggregator.html#gst-aggregator-finish-buffer" title="gst_aggregator_finish_buffer ()"><code class="function">gst_aggregator_finish_buffer()</code></a> method. This method will take care
of sending and ordering mandatory events such as stream start, caps
and segment.
</p></li>
<li class="listitem"><p>
Same goes for EOS events, which should not be pushed directly by the
subclass, it should instead return GST_FLOW_EOS in its aggregate
implementation.
</p></li>
</ul></div>
</div>
<div class="refsect1">
<a name="GstAggregator.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="gst-aggregator-finish-buffer"></a><h3>gst_aggregator_finish_buffer ()</h3>
<pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>
gst_aggregator_finish_buffer (<em class="parameter"><code><a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a> *agg</code></em>,
<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>);</pre>
<p>This method will take care of sending mandatory events before pushing
the provided buffer.</p>
<div class="refsect3">
<a name="id-1.2.7.2.7.2.5"></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>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>buffer</p></td>
<td class="parameter_description"><p>the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="type">GstBuffer</span></a> to push.</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-aggregator-set-src-caps"></a><h3>gst_aggregator_set_src_caps ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_aggregator_set_src_caps (<em class="parameter"><code><a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a> *agg</code></em>,
<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="type">GstCaps</span></a> *caps</code></em>);</pre>
<p>Sets the caps to be used on the src pad.</p>
<div class="refsect3">
<a name="id-1.2.7.2.7.3.5"></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>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>caps</p></td>
<td class="parameter_description"><p>The <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="type">GstCaps</span></a> to set later on the src pad.</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-aggregator-iterate-sinkpads"></a><h3>gst_aggregator_iterate_sinkpads ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
gst_aggregator_iterate_sinkpads (<em class="parameter"><code><a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a> *self</code></em>,
<em class="parameter"><code><span class="type">GstAggregatorPadForeachFunc</span> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>Iterate the sinkpads of aggregator to call a function on them.</p>
<p>This method guarantees that <em class="parameter"><code>func</code></em>
will be called only once for each
sink pad.</p>
<div class="refsect3">
<a name="id-1.2.7.2.7.4.6"></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>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="GstAggregator.html" title="GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>func</p></td>
<td class="parameter_description"><p>The function to call.</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>user_data</p></td>
<td class="parameter_description"><p>The data to pass to <em class="parameter"><code>func</code></em>
.</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="GstAggregator.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstAggregator-struct"></a><h3>struct GstAggregator</h3>
<pre class="programlisting">struct GstAggregator;</pre>
<p>Collectpads object.</p>
<div class="refsect3">
<a name="id-1.2.7.2.8.2.5"></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></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="GstAggregatorClass"></a><h3>struct GstAggregatorClass</h3>
<pre class="programlisting">struct GstAggregatorClass {
GstElementClass parent_class;
GType sinkpads_type;
GstFlowReturn (*flush) (GstAggregator * aggregator);
GstFlowReturn (*clip) (GstAggregator * agg,
GstAggregatorPad * bpad,
GstBuffer * buf,
GstBuffer ** outbuf);
/* sinkpads virtual methods */
gboolean (*sink_event) (GstAggregator * aggregate,
GstAggregatorPad * bpad,
GstEvent * event);
gboolean (*sink_query) (GstAggregator * aggregate,
GstAggregatorPad * bpad,
GstQuery * query);
/* srcpad virtual methods */
gboolean (*src_event) (GstAggregator * aggregate,
GstEvent * event);
gboolean (*src_query) (GstAggregator * aggregate,
GstQuery * query);
gboolean (*src_activate) (GstAggregator * aggregator,
GstPadMode mode,
gboolean active);
GstFlowReturn (*aggregate) (GstAggregator * aggregator);
gboolean (*stop) (GstAggregator * aggregator);
gboolean (*start) (GstAggregator * aggregator);
};
</pre>
<p>The aggregator base class will handle in a thread-safe way all manners of
concurrent flushes, seeks, pad additions and removals, leaving to the
subclass the responsibility of clipping buffers, and aggregating buffers in
the way the implementor sees fit.</p>
<p>It will also take care of event ordering (stream-start, segment, eos).</p>
<p>Basically, a basic implementation will override <em class="parameter"><code>aggregate</code></em>
, and call
_finish_buffer from inside that function.</p>
<div class="refsect3">
<a name="id-1.2.7.2.8.3.7"></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/GstElement.html#GstElementClass"><span class="type">GstElementClass</span></a> <em class="structfield"><code><a name="GstAggregatorClass.parent-class"></a>parent_class</code></em>;</p></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="struct_member_name"><p><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> <em class="structfield"><code><a name="GstAggregatorClass.sinkpads-type"></a>sinkpads_type</code></em>;</p></td>
<td class="struct_member_description"><p>Optional.
The type of the pads that should be created when
GstElement.request_new_pad is called.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.flush"></a>flush</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called after a succesful flushing seek, once all the flush
stops have been received. Flush pad-specific data in
<a class="link" href="GstAggregatorPad.html" title="GstAggregatorPad"><span class="type">GstAggregatorPad</span></a>->flush.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.clip"></a>clip</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a buffer is received on a sink pad, the task
of clipping it and translating it to the current segment
falls on the subclass.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.sink-event"></a>sink_event</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when an event is received on a sink pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.sink-query"></a>sink_query</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a query is received on a sink pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-event"></a>src_event</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when an event is received on the src pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-query"></a>src_query</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a query is received on the src pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-activate"></a>src_activate</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when the src pad is activated, it will start/stop its
pad task right after that call.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.aggregate"></a>aggregate</code></em> ()</p></td>
<td class="struct_member_description"><p>Mandatory.
Called when buffers are queued on all sinkpads. Classes
should iterate the GstElement->sinkpads and peek or steal
buffers from the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-bad-libs/html/GstAggregatorPad.html"><span class="type">GstAggregatorPads</span></a>. If the subclass returns
GST_FLOW_EOS, sending of the eos event will be taken care
of. Once / if a buffer has been constructed from the
aggregated buffers, the subclass should call _finish_buffer.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.stop"></a>stop</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Should be linked up first. Called when the
element goes from PAUSED to READY. The subclass should free
all resources and reset its state.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.start"></a>start</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Should be linked up first. Called when the element goes from
READY to PAUSED. The subclass should get ready to process
aggregated buffers.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="GstAggregator.see-also"></a><h2>See Also</h2>
<p>gstcollectpads for historical reasons.</p>
</div>
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