gstreamer/docs/manual/queues.sgml

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<chapter id="cha-queues">
<title>Queues</title>
<para>
A <classname>GstQueue</classname> is a filter element.
Queues can be used to connect two elements in such way that the data can
be buffered.
</para>
<para>
A buffer that is sinked to a Queue will not automatically be pushed to the
next connected element but will be buffered. It will be pushed to the next
element as soon as gst_connection_push () is called.
</para>
<para>
Queues are mostly used in conjunction with a <classname>GstThread</classname> to
provide an external connection for the thread elements. You could have one
thread feeding buffers into a <classname>GstQueue</classname> and another
thread repeadedly calling gst_connection_push () on the queue to feed its
internal elements.
</para>
<para>
Below is a figure of a two-threaded decoder. We have one thread (the main execution
thread) reading the data from a file, and another thread decoding the data.
</para>
<figure float="1" id="sec-queues-img">
<title>a two-threaded decoder with a queue</title>
<graphic fileref="images/queue" format="png"></graphic>
</figure>
</chapter>