mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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5e8b9eb005
Original commit message from CVS: Lots of updates. Added a chapter about the autoplugcache. Updated the autoplug example using the autoplugcache. Moved some stuff around. Added an example app for gst_parse_launch. Updated the debug info.
240 lines
6.9 KiB
Text
240 lines
6.9 KiB
Text
<chapter id="cha-programs">
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<title>Programs</title>
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<para>
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</para>
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<sect1>
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<title><command>gstreamer-config</command></title>
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<para>
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<command>gstreamer-config</command> is a script to get information about the installed
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version of <application>GStreamer</application>.
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This program "knows" what compiler switches are needed to compile programs that use
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<application>GStreamer</application>.
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</para>
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<para>
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<command>gstreamer-config</command> accepts the following options:
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<itemizedlist>
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<listitem>
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<para>
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<option>--version</option> Print the currently installed version of
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<application>GStreamer</application> on the standard output.
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</para>
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</listitem>
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<listitem>
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<para>
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<option>--libs</option> Print the linker flags that are necessary to link a
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<application>GStreamer</application> program.
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</para>
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</listitem>
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<listitem>
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<para>
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<option>--cflags</option> Print the compiler flags that are necessary to compile a
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<application>GStreamer</application> program.
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</para>
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</listitem>
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<listitem>
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<para>
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<option>--prefix=<replaceable>PREFIX</replaceable></option>
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If specified, use <replaceable>PREFIX</replaceable> instead of the installation
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prefix that <application>GStreamer</application> was built with when computing the
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output for the <option>--cflags</option> and <option>--libs</option> options.
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This option is also used for the exec prefix if
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<option>--exec-prefix</option> was not specified. This option must be specified before any
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<option>--libs</option> or <option>--cflags</option> options.
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</para>
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</listitem>
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<listitem>
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<para>
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<option>--exec-prefix=<replaceable>PREFIX</replaceable></option>
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If specified, use <replaceable>PREFIX</replaceable> instead of the installation exec
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prefix that <application>GStreamer</application> was built with when computing the
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output for the <option>--cflags</option> and <option>--libs</option> options. This option must be
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specified before any <option>--libs</option> or <option>--cflags</option>
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options.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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A simple <filename>Makefile</filename> will contain something like:
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<programlisting>
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CC = gcc
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helloworld2: helloworld2.c
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$(CC) -Wall `gstreamer-config --cflags --libs` helloworld2.c -o helloworld2
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clean:
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rm -f *.o helloworld2
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</programlisting>
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</para>
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</sect1>
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<sect1>
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<title><command>gstreamer-register</command></title>
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<para>
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<command>gstreamer-register</command> is used to rebuild the database of plugins.
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It is used after a new plugin has been added to the system. The plugin database
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can be found in <filename>/etc/gstreamer/reg.xml</filename>.
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</para>
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</sect1>
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<sect1>
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<title><command>gstreamer-launch</command></title>
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<para>
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This is a tool that will construct pipelines based on a command-line
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syntax.
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</para>
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<para>
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A simple commandline looks like:
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<screen>
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gstreamer-launch disksrc location=hello.mp3 ! mp3parse ! mpg123 ! audiosink
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</screen>
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A more complex pipeline looks like:
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<screen>
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gstreamer-launch disksrc redpill.vob audio_00! (ac3parse ! ac3dec ! audiosink) \
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video_00! (mpeg2dec ! videosink)
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</screen>
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</para>
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<para>
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Note that the parser isn't capable of more complex pipelines yet, including
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the VOB player above. The minor tweaks will be made post 0.2.1.
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</para>
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<para>
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You can also use the the parser in you own code. <application>GStreamer</application>
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provides a function gst_parse_launch () that you can use to construt a pipeline.
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The following programs lets you create an mp3 pipeline using the gst_parse_launch ()
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function:
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</para>
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<programlisting>
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#include <gst/gst.h>
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int
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main (int argc, char *argv[])
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{
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GstElement *pipeline;
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GstElement *disksrc;
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gst_init (&argc, &argv);
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if (argc != 2) {
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g_print ("usage: %s <filename>\n", argv[0]);
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return -1;
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}
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pipeline = gst_pipeline_new ("my_pipeline");
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gst_parse_launch ("disksrc[my_disksrc] ! mp3parse ! mpg123 ! osssink", GST_BIN (pipeline));
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disksrc = gst_bin_get_by_name (GST_BIN (pipeline), "my_disksrc");
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g_object_set (G_OBJECT (disksrc), "location", argv[1], NULL);
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gst_element_set_state (pipeline, GST_STATE_PLAYING);
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while (gst_bin_iterate (GST_BIN (pipeline)));
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gst_element_set_state (pipeline, GST_STATE_NULL);
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return 0;
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}
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</programlisting>
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<para>
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Note how we can retrieve the disksrc element from the constructed bin using the
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element name.
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</para>
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</sect1>
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<sect1>
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<title><command>gstreamer-inspect</command></title>
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<para>
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This is a tool to query a plugin or an element about its properties.
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</para>
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<para>
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To query the information about the element mpg123, you would specify:
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</para>
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<screen>
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gstreamer-inspect mpg123
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</screen>
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<para>
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Below is the output of a query for the audiosink element:
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</para>
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<screen>
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Factory Details:
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Long name: Audio Sink (OSS)
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Class: Sink/Audio
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Description: Output to a sound card via OSS
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Version: 0.1.0
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Author(s): Erik Walthinsen <omega@cse.ogi.edu>
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Copyright: (C) 1999
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Pad Templates:
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SINK template: 'sink'
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Exists: Always
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Capabilities:
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'audiosink_sink':
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MIME type: 'audio/raw':
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format: Integer: 16
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depth: List:
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Integer: 8
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Integer: 16
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rate: Integer range: 8000 - 48000
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channels: Integer range: 1 - 2
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Element Flags:
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GST_ELEMENT_THREADSUGGESTED
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no flags set
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Element Implementation:
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No loopfunc(), must be chain-based or not configured yet
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Has change_state() function
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Pads:
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SINK: 'sink'
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Implementation:
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Has chainfunc(): 0x4001cde8
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Has default eosfunc() gst_pad_eos_func()
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Pad Template: 'sink'
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Capabilities:
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'audiosink_sink':
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MIME type: 'audio/raw':
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format: Integer: 16
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depth: List:
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Integer: 8
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Integer: 16
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rate: Integer range: 8000 - 48000
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channels: Integer range: 1 - 2
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Element Arguments:
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GstAudioSink::mute: Boolean
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GstAudioSink::format: Enum (default 16)
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(8): 8 Bits
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(16): 16 Bits
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GstAudioSink::channels: Enum (default 2)
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(1): Mono
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(2): Stereo
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GstAudioSink::frequency: Integer
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</screen>
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<para>
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To query the information about a plugin, you would do:
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</para>
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<screen>
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gstreamer-inspect gstelements
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</screen>
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</sect1>
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<sect1>
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<title><command>gstmediaplay</command></title>
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<para>
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A sample media player.
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</para>
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</sect1>
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</chapter>
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