gstreamer/docs/manual/programs.sgml

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

  <sect1>
    <title><command>gstreamer-config</command></title>
    <para> 
      <command>gstreamer-config</command> is a script to get information about the installed 
      version of <application>GStreamer</application>.
      This program "knows" what compiler switches are needed to compile programs that use 
      <application>GStreamer</application>. 
    </para>
      
    <para> 
      <command>gstreamer-config</command> accepts the following options:
 
     <itemizedlist>
       <listitem>
         <para>
          <option>--version</option> Print the currently installed version of 
	     <application>GStreamer</application> on the standard output. 
         </para>
       </listitem>
       <listitem>
         <para>
          <option>--libs</option> Print the linker flags that are necessary to link a 
	    <application>GStreamer</application> program. 
         </para>
       </listitem>
       <listitem>
         <para>
           <option>--cflags</option> Print the compiler flags that are necessary to compile a 
	     <application>GStreamer</application> program. 
         </para>
       </listitem>
       <listitem>
         <para>
           <option>--prefix=<replaceable>PREFIX</replaceable></option>
             If specified, use <replaceable>PREFIX</replaceable> instead of the installation 
	     prefix that <application>GStreamer</application> was built with when computing the
             output for the <option>--cflags</option> and <option>--libs</option> options. 
	     This option is also used for the exec prefix if 
	     <option>--exec-prefix</option> was not specified. This option must be specified before any 
	     <option>--libs</option> or <option>--cflags</option> options. 
         </para>
       </listitem>
       <listitem>
         <para>
           <option>--exec-prefix=<replaceable>PREFIX</replaceable></option> 
             If specified, use <replaceable>PREFIX</replaceable> instead of the installation exec 
	     prefix that <application>GStreamer</application> was built with when computing the
             output for the <option>--cflags</option> and <option>--libs</option> options. This option must be 
	     specified before any <option>--libs</option> or <option>--cflags</option>
             options. 
         </para>
       </listitem>
     </itemizedlist>
    </para>
    <para>
      A simple <filename>Makefile</filename> will contain something like:
      <programlisting>
CC = gcc

helloworld2: helloworld2.c
   $(CC) -Wall `gstreamer-config --cflags --libs` helloworld2.c -o helloworld2

clean:
   rm -f *.o helloworld2
      </programlisting>
    </para>
  </sect1>

  <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 disksrc location=hello.mp3 ! mp3parse ! mpg123 ! audiosink
    </screen>

      A more complex pipeline looks like:

    <screen>
gstreamer-launch disksrc 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 0.1.0.
    </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 code of gstreamer-launch actually looks like:
    </para>
    <programlisting>
#include &lt;gst/gst.h&gt;
#include &lt;string.h&gt;
#include &lt;stdlib.h&gt;

int 
main(int argc, char *argv[]) 
{
  GstElement *pipeline;
  char **argvn;
  gchar *cmdline;
  int i;

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

  pipeline = gst_pipeline_new("launch");

  // make a null-terminated version of argv
  argvn = g_new0(char *,argc);
  memcpy(argvn,argv+1,sizeof(char*)*(argc-1));
  // join the argvs together
  cmdline = g_strjoinv(" ",argvn);
  // free the null-terminated argv
  g_free(argvn);

  gst_parse_launch(cmdline,pipeline);

  fprintf(stderr,"RUNNING pipeline\n");
  gst_element_set_state(pipeline,GST_STATE_PLAYING);

  while (1)
    gst_bin_iterate (GST_BIN (pipeline));

  return 0;
}
    </programlisting>
  </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>