docs/random/example

   1 Here's a pipeline that does audio/video MPEG streams with a queue on
   2 either side of each decompressor, for a total of 5 threads (read/split,
   3 decode audio, decode video, play audio, play video):
   4
   5 NOTES: mpegsplit is the intelligence in this pipeline, providing an IDL
   6 that allows one to connect things to a GUI.
   7
   8 Pipeline(mpegplay)
   9         Thread(reader)
  10                 Element(:disk_async_src) [StreamerAsyncSrc]
  11                         OutPad(disk1)
  12                 Element(:mpegsplit)
  13                         InPad(disk1)
  14                         OutPad(audio1)
  15                         OutPad(video1)
  16
  17         Queue(audioQ1)
  18                 InPad(audio1)
  19                 OutPad(audio2)
  20         Thread(audiodecode)
  21                 Element(:mpeg_audio_decode) [StreamerVideoFilter]
  22                         InPad(audio2)
  23                         OutPad(audio3)
  24         Queue(audioQ2)
  25                 InPad(audio3)
  26                 OutPad(audio4)
  27         Thread(audioplay)
  28                 Element(:audio_play) [StreamerAudioSink]
  29                         InPad(audio4)
  30
  31         Queue(videoQ1)
  32                 InPad(video1)
  33                 OutPad(video2)
  34         Thread(videodecode)
  35                 Element(:mpeg_video_decode) [StreamerVideoFilter]
  36                         InPad(video2)
  37                         OutPad(video3)
  38         Queue(videoQ2)
  39                 InPad(video3)
  40                 OutPad(video4)
  41         Thread(videoplay)
  42                 Element(:video_play) [StreamerVideoSink]
  43                         InPad(video4)
  44
  45
  46 A simpler pipeline that just does MPEG videos:
  47
  48 Pipeline(mpegplay)
  49         Thread(reader)
  50                 Element(:disk_async_src) [GstAsyncSrc]
  51                         OutPad(disk1)
  52                 Element(:mpeg_control)
  53                         InPad(disk1)
  54                         OutPad(video1)
  55                 Element(:mpeg_video_decode) [GstVideoFilter]
  56                         InPad(video1)
  57                         InPad(video2)
  58         Queue(queue)
  59                 InPad(video2)
  60                 OutPad(video3)
  61         Thread(play)
  62                 Element(:video_play) [GstVideoSink]
  63                         InPad(video3)
  64
  65 The code for the above looks roughly like:
  66
  67 /* all the objects we're worried about */
  68 GstPipeline *mpegplay;
  69 GstThread *reader;
  70 GstSrc *disk_src;
  71 GstControl *mpeg_control;
  72 GstFilter *mpeg_video_decode;
  73 GstQueue *queue;
  74 GstThread *play;
  75 GstSink *video_play;
  76
  77 /*** first we create all of the objects ***/
  78
  79 mpegplay = gst_pipeline_new();
  80 reader = gst_thread_new();
  81 disk_src = gst_async_disk_src_new("filename.mpg");
  82 mpeg_control = gst_mpeg_control_new();
  83 mpeg_video_decode = gst_mpeg_video_decode_new();
  84 queue = gst_queue_new();
  85 play = gst_thread_new();
  86 video_play = gst_video_sink_new();
  87
  88
  89 /*** now we start to create the pipeline ***/
  90
  91 /* first set up the reader thread */
  92 gst_bin_add(reader,disk_src);
  93 gst_object_connect(disk_src,"out",mpeg_control,"in");
  94 gst_object_connect(mpeg_control,"out",mpeg_audio_decode,"in");
  95 gst_bin_ghost_pad(reader,mpeg_audio_decode,"out");
  96
  97 /* then set up the player thread */
  98 gst_bin_add(play,audio_play);
  99 gst_bin_ghost_pad(play,audio_play,"in");
 100
 101 /* now plug them all into the main pipeline */
 102 gst_bin_add(mp3play,reader);
 103 gst_object_connect(reader,"out",queue,"in");
 104 gst_object_connect(queue,"out",play,"in");