Applications

Gstreamer

Home page
QtMultimedia, FFMpeg, Gstreamer: comparing multimedia frameworks
http://www.einarsundgren.se/gstreamer-basic-real-time-streaming-tutorial/
Original documetation from source code
http://wiki.oz9aec.net/index.php/Gstreamer_cheat_sheet
http://www.cin.ufpe.br/~cinlug/wiki/index.php/Introducing_GStreamer
http://www.jonobacon.org/2006/12/27/using-gnonlin-with-gstreamer-and-python/
https://felipec.wordpress.com/2008/01/19/gstreamer-hello-world/
http://notes.brooks.nu/2011/01/gstreamer-video-crossfade-example/
http://www.oz9aec.net/index.php/gstreamer/366-gstinputselector-to-switch-between-different-cameras
Picture compositing
https://github.com/fthiery/gst-gengui
https://github.com/guijemont/GstStabilizer
http://www.oz9aec.net/index.php/gstreamer/345-a-weekend-with-gstreamer
https://github.com/umlaeute/v4l2loopback/wiki/Gstreamer
http://cgit.freedesktop.org/gstreamer/gst-python/tree/examples/switch.py
Queue after tee
Some tricks to get "easy" stuffs out of GStreamer.
GNonlin example
http://luisbg.blogalia.com/historias/61887
http://www.jonobacon.org/2006/08/28/getting-started-with-gstreamer-with-python/
http://pygstdocs.berlios.de/
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-dynamic-pipelines.html
http://wiki.pitivi.org/wiki/PyGST_Tutorial/Combining_Audio_and_Video
https://answers.opencv.org/question/202017/how-to-use-gstreamer-pipeline-in-opencv/
gst-inference A GStreamer Deep Learning Inference Framework
Creating Gstreamer Multimedia Pipeline With C++ Part 2
Debugging tools
http://lifestyletransfer.com/how-to-use-gstreamer-appsink-in-python/
Implementing an audio plotter

First of all, a video came with two main types of data: audio and video. Since space is important, is important to compress data but since quality is important also, during the years has been developed a lot of codecs (this name came from their functions: coder and encoder). For a technical video overview look at the Xiph videos.

$ gst-launch -v -e  filesrc location="/home/gipi/Video/Nature by Numbers.mp4"  ! \
        qtdemux name=avi ! faad  ! pulsesink

And remember is not only about multimedia: http://www.cita.utoronto.ca/~kcannon/gstlalworkshop/intro_and_setup.html

PIPELINES

Play with guessing

$ gst-launch -v playbin uri="file:///home/gipi/Video/Nature by Numbers.mp4"

Play an image

$ gst-launch-1.0 multifilesrc location=tmp_frames/frame_%02d.png caps="image/png, framerate=1/1" ! \
    pngdec ! \
    videoconvert ! \
    autovideosink

Autodetect streams and play it

$ gst-launch-1.0 -v --gst-debug=4 filesrc location=//streaming.mp4 ! \
        decodebin name=demux \
        demux. ! queue ! autovideosink \
        demux. ! queue ! autoaudiosink

Show your webcam

$ gst-launch-1.0 v4l2src  ! autovideosink

and now composite with a test pattern

$ gst-launch -e v4l2src ! \
        queue ! \
        ffmpegcolorspace ! \
        videoscale ! \
        video/x-raw-yuv, framerate=10/1, width=320, height=240 ! \
        videomixer name=mix ! \
        ffmpegcolorspace ! \
        xvimagesink \
        videotestsrc ! video/x-raw-yuv, framerate=10/1, width=640, height=360 ! mix.

Composite two videos, rescaling them to 900x600 pixels

$ gst-launch-1.0  -v  \
    filesrc location='0870_00_60.mkv' ! \
    decodebin ! \
    queue ! \
    videoscale ! video/x-raw,width=900,height=600 ! \
    queue ! videobox border-alpha=0 left=-900  ! videomixer name=mix ! \
    videoconvert ! timeoverlay ! autovideosink \
    filesrc location='0870_00_60.mkv' ! decodebin ! \
    queue ! \
    videoscale ! video/x-raw,width=900,height=600 ! \
    queue ! videobox border-alpha=0 left=0 ! mix.

Show an overlay over the video

$ gst-launch-1.0 videotestsrc ! timeoverlay font-desc=60px ! xvimagesink

Resize the output

$ gst-launch-1.0 -v filesrc location=assange-ecuador.mp4 ! decodebin ! \
        videoscale ! \
        video/x-raw,width=\(int\)320,height=\(int\)200 ! \
        autovideosink filter-caps=video/x-raw

Create a video stream from an image

$ gst-launch-1.0 filesrc location=image001.jpg ! jpegdec ! imagefreeze ! autovideosink

Remote resource via HTTP

$ gst-launch-1.0 souphttpsrc location=http://foo.com/miao.mp3 ! autoaudiosink

Attach to a mountpoint of icecast

$ gst-launch -v filesrc location=audio/04\ -\ Blu\ di\ metilene.ogg ! \
        decodebin ! \
        audioconvert ! \
        vorbisenc  !  \
        oggmux ! \
        shout2send ip=localhost port=8000 mount=/lov

Icecast, you know

$ gst-launch v4l2src ! \
        queue ! \
        ffmpegcolorspace ! \
        videoscale ! \
        video/x-raw-yuv,width=320,height=240 ! \
        tee name=tscreen ! \
        queue ! \
        autovideosink \
        tscreen. ! \
        queue ! \
        videorate ! \
        video/x-raw-yuv,framerate=25/2 ! \
        queue ! \
        theoraenc quality=16 ! \
        queue ! \
        oggmux name=mux \
        alsasrc ! \
        queue ! \
        audioconvert ! \
        vorbisenc quality=0.2 ! \
        queue ! \
        queue ! \
        mux. \
        mux. ! \
        queue ! \
        tee name=tfile ! \
        queue ! \
        filesink location=stream.ogg tfile. ! \
        queue ! \
        shout2send ip=192.168.0.5 port=8000 mount=test.ogv password=sourcepassword

From an IP camera that serves JPEG images (multipartdemux is useless)

$ gst-launch souphttpsrc location=http://192.168.1.5:8080/videofeed ! \
    multipartdemux ! \
    jpegdec ! \
    xvimagesink

A simple test with audio

$ gst-launch -v audiotestsrc  wave=ticks ! audioconvert !  pulsesink

Send audio to a given pulse device

$ gst-launch -v filesrc location="yet-another-amazing-song.mp3" ! \
 decodebin ! \
 audioconvert ! \
 pulsesink device=nullsinkname

(the device can be a null sink created with pactl load-module module-null-sink sink_name=nullsinkname)

Screencast

$ gst-launch-1.0 ximagesrc ! \
    videoconvert ! \
    queue ! \
    vp8enc  ! mux. \
   pulsesrc ! audio/x-raw ! \
    queue ! \
    audioconvert ! \
    vorbisenc ! \
   mux. webmmux name=mux ! filesink location=screencast.webm

$ gst-launch-1.0 --eos-on-shutdown  ximagesrc xid=0x9400014 show-pointer=true use-damage=false  ! \
  videoconvert ! \
  queue ! \
  x264enc pass=5 quantizer=26 speed-preset=6 ! \
  mp4mux fragment-duration=500 ! \
  filesink location=output.mp4

Tee

gst-launch-1.0 \
 multifilesrc location=tmp_frames/frame_%02d.png caps="image/png, framerate=1/1" ! \
 pngdec ! \
 videoconvert ! \
 video/x-raw ! \
 queue ! tee name=t ! \
 queue ! videoconvert ! autovideosink \
 t. ! queue ! autovideosink

Muxing

$ gst-launch-1.0 -v -e v4l2src ! \
  video/x-raw ! \
  videoconvert ! \
  vp8enc ! tee name=t ! \
  queue ! \
  matroskamux name=m ! filesink location=1.mkv  \
  pulsesrc ! vorbisenc ! \
  m.   \
  t. ! \
  queue ! webmmux ! filesink location=1.webm

Build from source

Using scripts/create-uninstalled-setup.sh is possible to create a checkout of the sources needed in ~/gst; in that directory a script gst-head is created: this is useful in order to configure all the environment variables correctly and make the build success.

Tmux

By default uses Ctrl-b as a control sequence

Command	Description
new	create new session
attach	attach to an already created session
ls

Sessions

Key	Description
`s`	visualize sessions and allow to switch between them
`$`	rename session
`(`	move to the previous session
`)`	move to the next session

Windows

Key	Description
`c`	create
`w`	list
`n`	next
`p`	previous
`f`	find
`,`	name
`&`	kill
`l`	last

Panes

Key	Description
`%`	vertical split
`"`	horizontal split
`o`	swap
`q`	show pane number
`+`	break pane into windows
`-`	restore pane from window
`z`	maximize
`<space>`	switch between layouts
`{`	move pan to the left
`}`	move pan to the right
`t`	big clock

Clipboard

tmux has its own clipboard and it's useful to copy and paste stuff from a window/pane to another.

Key	Description
`[`	enter copy mode
`space`	start selection
`]`	paste

An unusual key binding here is for copying into the tmux's clipboard that is Alt + w. Otherwise enter is good enough but exit from copy mode altogether.

ImageMagick

Create a 2x2 composite image

$ convert \
    \( 1.jpeg 2.jpeg +append \) \
    \( 3.jpeg 4.jpeg +append \) \
    -append output.jpg