View source for GST cookbook

In addition to being a powerful multimedia infrastructure for applications Gstreamer is also a useful tool for general manipulations of multimedia data.  By invoking gst-launch from the command-line with a custom pipeline many useful processing steps are possible.

Gstreamer also usually has good support for Xiph-related formats. 

Unfortunately, it can be rather difficult to figure out an appropriate pipeline without a starting point.

Here are some useful examples: <!-- Don't complain about the selection of examples, I started this simply by grepping my shell history. Feel free to submit more and/or improve the existing ones --gmaxwell -->

===Encode a .wav to Vorbis:===
*gst-launch filesrc location="INPUT.wav"  ! wavparse ! audioconvert ! vorbisenc ! oggmux ! filesink location="OUTPUT.ogg"

===Dump a Theora video to PNGs:===
*gst-launch filesrc location="INPUT.ogv" !  oggdemux ! theoradec ! ffmpegcolorspace ! pngenc snapshot=false ! multifilesink location="OUTPUT%04d.png"

===Transmux a MKV (containing vorbis and theora) to Ogg:===
*gst-launch filesrc location="INPUT.mkv" ! matroskademux name=d ! video/x-theora ! queue ! theoraparse ! oggmux name=mux ! filesink location="OUTPUT.ogv" d. ! audio/x-vorbis ! queue ! vorbisparse ! queue ! mux.

===Encode a y4m to lossless Dirac in Ogg:===
*gst-launch filesrc location="INPUT.y4m" ! decodebin ! schroenc force-profile=vc2_main rate-control=lossless ! oggmux ! filesink location="OUTPUT.ogv"

===Pull from a windows media stream, transcode to Ogg/Thera+Vorbis and send to a icecast server:===
(requires purchasing fluendo plugins for decoding the encumbered codecs)
*gst-launch uridecodebin uri=mms://SOURCE.SERVER.COM/path name=d ! queue max-size-time=100000000 ! ffmpegcolorspace ! theoraenc bitrate=800 ! oggmux name=mux ! shout2send ip=YOURICECAST.SERVER.COM port=8000 password=YOURPASSWORD mount=/OUTPUTFILENAME.ogv d. ! queue max-size-time=100000000 ! audioconvert ! vorbisenc ! mux.

===Capture video from a webcam, encode to an Ogg Theora file, decode and display on screen, write to a file whose name is the current date+time, and stream to an IceCast server===
*gst-launch-0.10 --eos-on-shutdown v4l2src ! 'video/x-raw-yuv, width=640, height=480' ! videorate ! 'video/x-raw-yuv, framerate=15/1' ! queue max-size-bytes=100000000 max-size-time=0 ! theoraenc bitrate=150 ! oggmux ! tee name=ogged ! queue max-size-bytes=100000000 max-size-time=0 ! oggdemux ! theoradec ! xvimagesink sync=false force-aspect-ratio=true ogged. ! queue max-size-bytes=100000000 max-size-time=0 ! filesink location=`date +%F_%T`.ogv ogged. ! queue max-size-bytes=100000000 max-size-time=0 ! shout2send ip=YOURICECAST.SERVER.COM port=8000 password=YOURPASSWORD mount=/OUTPUTFILENAME.ogv streamname=YOURSTREAMNAME description=YOURDESCRIPTION genre=YOURGENRE url=YOURSTREAMURL ogged.

===A v4l2 source + ALSA source -> Ogg Theora -> IceCast===
*dov4l -i [0|1] -m NTSC
*gst-launch-0.10 --eos-on-shutdown v4l2src ! videoscale ! video/x-raw-yuv,width=320,height=240,framerate=30000/1001,interlaced=true ! queue max-size-bytes=100000000 max-size-time=0 ! gamma gamma=1.2 ! queue max-size-bytes=100000000 max-size-time=0 ! videobalance saturation=1.9 brightness=0.00 contrast=1.4 hue=0.06 ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0 ! theoraenc bitrate=400 ! queue max-size-bytes=100000000 max-size-time=0 ! oggmux name=mux alsasrc device=hw:1,0 latency-time=100 ! audioconvert ! vorbisenc ! queue max-size-bytes=100000000 max-size-time=0 ! mux. mux. ! queue max-size-bytes=100000000 max-size-time=0 ! shout2send ip=icecast-server.com  password=hackme mount=/mountpoint.ogv
:Note that the above pipeline will slowly lose audio/video synchronization due to hardware-level limitations in audio vs. video capture of media samples.  FireWire and SDI-based capture does not have these limitations.

===Two v4l2 sources combined side-by-side into rectangular video + ALSA -> Ogg Theora -> IceCast===
*mplayer tv:// -tv device=/dev/video0:driver=v4l2:norm=NTSC:width=320:height=240:outfmt=uyvy:input=1:buffersize=16: -ao null
*mplayer tv:// -tv device=/dev/video1:driver=v4l2:norm=NTSC:width=320:height=240:outfmt=uyvy:input=1:buffersize=16: -ao null
*gst-launch --eos-on-shutdown v4l2src device=/dev/video0 ! videoscale ! video/x-raw-yuv,width=320,height=240,interlaced=true ! queue max-size-bytes=100000000 max-size-time=0 ! gamma gamma=1.2 ! queue max-size-bytes=100000000 max-size-time=0 ! videobalance saturation=1.9 brightness=0.00 contrast=1.4 hue=0.06 ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0 ! videorate ! video/x-raw-yuv,framerate=15/1 ! queue max-size-bytes=100000000 max-size-time=0  ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0  ! videomixer name=mix ! queue max-size-bytes=100000000 max-size-time=0 ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0 ! theoraenc bitrate=600 ! queue max-size-bytes=100000000 max-size-time=0 ! oggmux name=mux alsasrc device=hw:1,0 latency-time=100 ! queue max-size-bytes=100000000 max-size-time=0 ! audioconvert ! vorbisenc ! queue max-size-bytes=100000000 max-size-time=0 ! mux. mux. ! queue max-size-bytes=100000000 max-size-time=0  ! shout2send ip=icecast-server.com password=hackme mount=/mountpoint.ogv  v4l2src device=/dev/video1 ! videoscale ! video/x-raw-yuv,width=320,height=240,interlaced=true ! gamma gamma=1.2 ! queue max-size-bytes=100000000 max-size-time=0 ! videobalance saturation=1.9 brightness=0.00 contrast=1.4 hue=0.06 !  queue max-size-bytes=100000000 max-size-time=0 ! videorate ! video/x-raw-yuv,framerate=5/1 ! queue max-size-bytes=100000000 max-size-time=0 ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0  ! videobox border-alpha=0 fill=green left=-320 ! mix.

===Create a video with an alpha channel from a sequence of PNG files===
*gst-launch-0.10 multifilesrc location=images%05d.png caps="image/png,framerate=1/1,pixel-aspect-ratio=1/1" num-buffers=95 ! pngdec ! videorate ! alphacolor ! "video/x-raw-yuv,format=(fourcc)AYUV" ! matroskamux ! filesink location=images_raw.mkv

===Capture from a 1680x1050 GNOME Desktop, Combine with ALSA -> Ogg Theora + Vorbis -> Icecast===
*gst-launch  --eos-on-shutdown ximagesrc ! capsfilter caps=video/x-raw-rgb,framerate=3/1,width=1680,height=1050  ! queue max-size-bytes=100000000 max-size-time=0 ! videoscale ! video/x-raw-rgb, width=1056, height=660 ! queue max-size-bytes=100000000 max-size-time=0 ! ffmpegcolorspace ! queue max-size-bytes=100000000 max-size-time=0 ! theoraenc bitrate=450 keyframe-auto=false keyframe-force=12 keyframe-freq=12 speed-level=0 drop-frames=false ! queue max-size-bytes=100000000 max-size-time=0 ! oggmux name=mux alsasrc device=hw:0,0 ! audio/x-raw-init,rate=44100,channels=1 ! queue max-size-bytes=100000000 ! audioconvert ! vorbisenc ! queue max-size-bytes=100000000 max-size-time=0 ! mux. mux. ! queue max-size-bytes=100000000 max-size-time=0 ! shout2send ip=icecast-server.com  password=hackme mount=/mountpoint.ogv
*Icecast will need to be built from SVN (ver. 2.3.2 fails to relay data due to a bug)
*Viewers will need better-than-average internet connectivity (at least 1.5Mbits/sec down?)
*The simplest way to capture audio events is to place a mic next to computer speakers
*Avoid pipeline underruns by launching 'gnome-at-properties', uncheck 'Enable assistive technologies', launch 'gconf-editor', navigate to 'apps/metacity/general' and check 'reduced_resources'.  This will enable wireframes while dragging windows and reduce other window animations, and is most helpful if slow window dragging spikes CPU usage.