mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-22 17:51:16 +00:00
018a6f381b
Original commit message from CVS: First draft of Chapter 1 (introduction) and Chapter 2 (basic concepts) of the GStreamer manual.
66 lines
2.5 KiB
Text
66 lines
2.5 KiB
Text
<chapter id="cha-bins">
|
|
<title>Bins</title>
|
|
<para>
|
|
A Bin is a container element. You can add elements to a bin. Since a bin is
|
|
an element itself, it can also be added to another bin.
|
|
</para>
|
|
<para>
|
|
Bins allow you to combine connected elements into one logical element. You do
|
|
not deal with the individual elements anymore but with just one element, the bin.
|
|
We will see that this is extremely powerfull when you are going to construct
|
|
complex pipelines since it allows you to break up the pipeline in smaller chunks.
|
|
</para>
|
|
<para>
|
|
The bin will also manage the elements contained in it. It will figure out how
|
|
the data will flow in the bin and generate an optimal plan for that data flow.
|
|
</para>
|
|
|
|
<figure float="1" id="sec-bin-img">
|
|
<title>Visualisation of a <classname>GstBin</classname> element with some elements in it</title>
|
|
<graphic fileref="images/bin-element" format="png"></graphic>
|
|
</figure>
|
|
|
|
<para>
|
|
There are two standard bins available to the GStreamer programmer:
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
A pipeline (<classname>GstPipeline</classname>). Which is a generic container you will
|
|
use most of the time.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
A thread (<classname>GstThread</classname>). All the elements in the thread bin will
|
|
run in a separate thread. You will haver to use this bin if you carfully have to
|
|
synchronize audio and video for example. You will learn more about threads in.. <!-- FIXME -->
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</para>
|
|
|
|
<para>
|
|
The application programmer can create custom bins packed with elements to perform a
|
|
specific task. This allow you to write an MPEG audio decoder with just the follwing lines
|
|
of code:
|
|
|
|
<programlisting>
|
|
|
|
// create the mp3player element
|
|
GstElement *mp3player = gst_elementfactory_make("mp3player","mp3player");
|
|
// set the source mp3 audio file
|
|
gtk_object_set(GTK_OBJECT(mp3player), "location", "helloworld.mp3", NULL);
|
|
// tell the mp3player to prepare itself
|
|
gst_element_set_state(GST_ELEMENT(mp3player),GST_STATE_READY);
|
|
// start playback
|
|
gst_element_set_state(GST_ELEMENT(mp3player),GST_STATE_PLAYING);
|
|
...
|
|
// pause playback
|
|
gst_element_set_state(GST_ELEMENT(mp3player),GST_STATE_PAUSED);
|
|
...
|
|
// stop
|
|
gst_element_set_state(GST_ELEMENT(mp3player),GST_STATE_NULL);
|
|
</programlisting>
|
|
</para>
|
|
</chapter>
|