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>Chapter 28. Autoplugging</H1
><P
>
<SPAN
CLASS="application"
>GStreamer</SPAN
> provides an API to automatically
construct complex pipelines based on source and destination capabilities.
This feature is very useful if you want to convert type X to type Y but
don't care about the plugins needed to accomplish this task. The
autoplugger will consult the plugin repository, select and link the
elements needed for the conversion.
</P
><P
>
The autoplugger API is implemented in an abstract class. Autoplugger
implementations reside in plugins and are therefore optional and can be
optimized for a specific task. Two types of autopluggers exist: renderer
ones and non-renderer ones. The renderer autopluggers will not have any
source pads while the non-renderer ones do. The renderer autopluggers are
mainly used for media playback while the non renderer ones are used for
arbitrary format conversion.
</P
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><A
NAME="AEN947"
>28.1. Using autoplugging</A
></H1
><P
>
You first need to create a suitable autoplugger with gst_autoplug_factory_make().
The name of the autoplugger must be one of the registered autopluggers..
</P
><P
> A list of all available autopluggers can be obtained with gst_autoplug_factory_get_list().
</P
><P
> If the autoplugger supports the RENDERER API, use the
gst_autoplug_to_renderers() function to create a bin that links
the source caps to the specified render elements. You can then add
the bin to a pipeline and run it.
<PRE
CLASS="programlisting"
>
GstAutoplug *autoplug;
GstElement *element;
GstElement *sink;
/* create a static autoplugger */
autoplug = gst_autoplug_factory_make ("staticrender");
/* create an osssink */
sink = gst_element_factory_make ("osssink", "our_sink");
/* create an element that can play audio/mp3 through osssink */
element = gst_autoplug_to_renderers (autoplug,
gst_caps_new (
"sink_audio_caps",
"audio/mp3",
NULL
),
sink,
NULL);
/* add the element to a bin and link the sink pad */
...
</PRE
>
</P
><P
> If the autoplugger supports the CAPS API, use the gst_autoplug_to_caps()
function to link the source caps to the destination caps. The created
bin will have source and sink pads compatible with the provided caps.
<PRE
CLASS="programlisting"
>
GstAutoplug *autoplug;
GstElement *element;
/* create a static autoplugger */
autoplug = gst_autoplug_factory_make ("static");
/* create an element that converts audio/mp3 to audio/raw */
element = gst_autoplug_to_caps (autoplug,
gst_caps_new (
"sink_audio_caps",
"audio/mp3",
NULL
),
gst_caps_new (
"src_audio_caps",
"audio/raw",
NULL
),
NULL);
/* add the element to a bin and link the src/sink pads */
...
</PRE
>
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