GStreamer

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Revision as of 15:22, 18 October 2007 by MitchellNCharity (talk | contribs) (Moved rest of GStreamer 101 from Programming_the_camera.)
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GStreamer 101

Examples

v4l2src can always be replaced by videotestsrc, and alsasrc by audiotestsrc.

Beginning of a normal video pipeline:

v4l2src ! queue ! videorate ! video/x-raw-yuv,framerate=15/1 ! videoscale ! video/x-raw-yuv,width=160,height=120 ! ...

Beginning of a normal audio pipeline:

alsasrc ! audio/x-raw-int,rate=8000,channels=1,depth=8 ! ...

Video encoding:

... ! ffmpegcolorspace ! theoraenc ! ...

Audio encoding:

... ! audioconvert ! vorbisenc ! ...

Video output:

... ! ffmpegcolorspace ! videoscale ! ximagesink

Audio output:

... ! audioconvert ! alsasink sync=false

Stdout:

... ! fdsink fd=1

Encode video+audio as ogg:

v4l2src ! queue ! ffmpegcolorspace ! theoraenc ! queue ! \
  oggmux name=mux  alsasrc ! queue ! audioconvert ! vorbisenc ! queue ! mux. mux. ! queue ! ...

A long version of videotestsrc ! ximagesink:

videotestsrc ! theoraenc ! oggmux ! oggdemux ! theoradec ! ffmpegcolorspace ! videoscale ! ximagesink

A long version of videotestsrc ! ximagesink &; audiotestsrc ! alsasink:

videotestsrc ! ffmpegcolorspace ! theoraenc ! queue ! \
  oggmux name=mux audiotestsrc ! audioconvert ! vorbisenc ! queue ! mux. mux. ! queue ! \
  oggdemux name=demux ! queue ! theoradec ! ffmpegcolorspace ! \
    ximagesink demux. ! queue ! vorbisdec ! audioconvert ! alsasink
Hangs on current fc6. MitchellNCharity 17:43, 12 June 2007 (EDT)

Live video streaming to an icecast server:

v4l2src ! ffmpegcolorspace ! videoscale ! video/x-raw-yuv,width=320,height=240 ! theoraenc quality=16 ! oggmux ! shout2send ip=192.168.1.100 port=8000 password=hackme mount=olpc.ogg

Live streaming to an icecast server:

v4l2src ! queue ! ffmpegcolorspace ! theoraenc quality=16 ! queue ! oggmux name=mux  alsasrc ! audio/x-raw-int,rate=8000,channels=1,depth=8 ! queue ! audioconvert ! vorbisenc ! queue ! mux. mux. ! \
  queue ! shout2send ip=... port=... password=... mount=/whatever.ogg

Notes

video size, framerate, and theoraenc quality

audio encoding

glive.py used wav rather than vorbis. Why?

Elements

Adapters:

Video characteristics:

Audio characteristics:

File I/O:

Video sources:

Audio sources:

Coding video:

Coding audio:

Wrapping:

Outputing video:

Outputting audio:

Not sure about:

Sending ogg to an icecast streaming server:

... ! shout2send ip=... port=... password=... mount=/whatever.ogg
gst-launch ... ! fdsink | oggfwd host port password mount
Regretabbly, it appears fc6, and thus olpc, does not include shout2send in gst-plugins-good-plugins. Nor does it have rpms for oggfwd, or other possible alternatives. You can grab a random binary of oggfwd from it's site, or compile shout2send from source. :( MitchellNCharity 17:43, 12 June 2007 (EDT)
Correction, shout2send is on the olpc. oggfwd is not. --Damonkohler 23:14, 13 September 2007 (EDT)

Doing live streaming video from an xo

Section TODO

  • Fill in blank sections.
  • Include snapshot recipes.
  • Discuss python interfacing.

See also

Other resources