gstreamer/docs/manual/programs.xml

<chapter id="cha-programs">
  <title>Programs</title>
  <para> 
  </para>

  <sect1>
    <title><command>gstreamer-register</command></title>
    <para> 
      <command>gstreamer-register</command> is used to rebuild the database of plugins.
      It is used after a new plugin has been added to the system. The plugin database
      can be found in <filename>/etc/gstreamer/reg.xml</filename>.
    </para>
  </sect1>

  <sect1>
    <title><command>gstreamer-launch</command></title>
    <para> 
      This is a tool that will construct pipelines based on a command-line
      syntax.  
    </para> 
    <para> 
      A simple commandline looks like:

    <screen>
gstreamer-launch filesrc location=hello.mp3 ! mp3parse ! mpg123 ! audiosink
    </screen>

      A more complex pipeline looks like:

    <screen>
gstreamer-launch filesrc redpill.vob audio_00! (ac3parse ! ac3dec ! audiosink) \
video_00! (mpeg2dec ! videosink)
    </screen>

    </para>
    <para>
      Note that the parser isn't capable of more complex pipelines yet, including
      the VOB player above.  The minor tweaks will be made post 0.2.1.
    </para>
    <para>
      You can also use the the parser in you own code. <application>GStreamer</application>
      provides a function gst_parse_launch () that you can use to construt a pipeline. 
      The following programs lets you create an mp3 pipeline using the gst_parse_launch () 
      function:
    </para>
    <programlisting>
#include &lt;gst/gst.h&gt;

int
main (int argc, char *argv[])
{
  GstElement *pipeline;
  GstElement *filesrc;

  gst_init (&amp;argc, &amp;argv);

  if (argc != 2) {
    g_print ("usage: %s &lt;filename&gt;\n", argv[0]);
    return -1;
  }
  pipeline = gst_pipeline_new ("my_pipeline");

  gst_parse_launch ("filesrc[my_filesrc] ! mp3parse ! mpg123 ! osssink", GST_BIN (pipeline));

  filesrc = gst_bin_get_by_name (GST_BIN (pipeline), "my_filesrc");
  g_object_set (G_OBJECT (filesrc), "location", argv[1], NULL);

  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  while (gst_bin_iterate (GST_BIN (pipeline)));

  gst_element_set_state (pipeline, GST_STATE_NULL);

  return 0;
}
    </programlisting>
    <para>
      Note how we can retrieve the filesrc element from the constructed bin using the
      element name.
    </para>
  </sect1>

  <sect1>
    <title><command>gstreamer-inspect</command></title>
    <para> 
      This is a tool to query a plugin or an element about its properties.
    </para> 
    <para> 
      To query the information about the element mpg123, you would specify:
    </para> 

    <screen>
gstreamer-inspect mpg123
    </screen>

    <para> 
      Below is the output of a query for the audiosink element:
    </para> 

    <screen>
Factory Details:
  Long name:	Audio Sink (OSS)
  Class:	Sink/Audio
  Description:	Output to a sound card via OSS
  Version:	0.1.0
  Author(s):	Erik Walthinsen &lt;omega@cse.ogi.edu&gt;
  Copyright:	(C) 1999

Pad Templates:
  SINK template: 'sink'
    Exists: Always
    Capabilities:
      'audiosink_sink':
        MIME type: 'audio/raw':
        format: Integer: 16
        depth: List:
          Integer: 8
          Integer: 16
        rate: Integer range: 8000 - 48000
        channels: Integer range: 1 - 2

Element Flags:
  GST_ELEMENT_THREADSUGGESTED
  no flags set

Element Implementation:
  No loopfunc(), must be chain-based or not configured yet
  Has change_state() function

Pads:
  SINK: 'sink'
    Implementation:
      Has chainfunc(): 0x4001cde8
      Has default eosfunc() gst_pad_eos_func()
    Pad Template: 'sink'
    Capabilities:
      'audiosink_sink':
        MIME type: 'audio/raw':
        format: Integer: 16
        depth: List:
          Integer: 8
          Integer: 16
        rate: Integer range: 8000 - 48000
        channels: Integer range: 1 - 2

Element Arguments:
  GstAudioSink::mute: Boolean
  GstAudioSink::format: Enum (default 16)
    (8): 	8 Bits
    (16): 	16 Bits
  GstAudioSink::channels: Enum (default 2)
    (1): 	Mono
    (2): 	Stereo
  GstAudioSink::frequency: Integer
    </screen>

    <para> 
      To query the information about a plugin, you would do:
    </para> 

    <screen>
gstreamer-inspect gstelements
    </screen>
  </sect1>
  <sect1>
    <title><command>gstmediaplay</command></title>
    <para> 
      A sample media player.
    </para>
  </sect1>

</chapter>