Basics (GStreamer command-line cheat sheet)

Playing content

For these,set SRC to be e.g. an mp4 file., e.g.

export SRC=/home/me/videos/test.mp4

### Play a video (with audio)

playbin is a magical element that can play anything:

gst-launch-1.0 playbin uri=file://$SRC

This works with video, audio, RTMP streams, and so much more.

The 'bin' in 'playbin' means that under-the-hood, it's a collection of elements. For example, we can achieve the same thing by going to the next level of elements, which separate the decoding part from the playing part:

gst-launch-1.0 filesrc location=$SRC ! decodebin ! playsink

Or, we can split down even further:

gst-launch-1.0 filesrc location=$SRC ! \
    qtdemux name=demux  demux.audio_0 ! queue ! decodebin ! audioconvert ! audioresample ! \
    autoaudiosink \
    demux.video_0 ! queue ! \
    decodebin ! videoconvert ! videoscale ! autovideosink

Play a video (no audio)

gst-launch-1.0 -v uridecodebin uri="file://$SRC" ! autovideosink

which could also have been done as:

gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! autovideosink

### Play just the audio from a video

gst-launch-1.0 -v uridecodebin uri="file://$SRC" ! autoaudiosink

### Visualise the audio:

gst-launch-1.0 filesrc location=$SRC ! qtdemux name=demux  demux.audio_0 ! queue ! decodebin ! audioconvert ! wavescope ! autovideosink

(or replace ‘wavescope with spectrascope or synaescope or spacescope)

Or even better visualisation:

gst-launch-1.0 filesrc location=$SRC ! decodebin ! tee name=t ! queue ! audioconvert ! wavescope style=color-lines shade-amount=0x00080402 ! alpha alpha=0.5 ! videomixer name=m background=black ! videoconvert ! vertigotv ! autovideosink t. ! queue ! audioconvert ! spacescope style=color-lines shade-amount=0x00080402 ! alpha alpha=0.5 ! m. t. ! queue ! autoaudiosink

Add filters

Go slightly mad:

gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! videoconvert ! vertigotv ! autovideosink

Try also ‘rippletv’, ‘streaktv’, ‘radioactv’, ‘optv’, ‘quarktv’, ‘revtv’, ‘shagadelictv’, ‘warptv’ (I like), ‘dicetv’, ‘agingtv’ (great), ‘edgetv’ (could be great on real stuff)

Resize video

gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! videoconvert ! videoscale ! video/x-raw,width=100 ! autovideosink

Change framerate

gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! videoconvert !  videorate ! video/x-raw,framerate=5/1  ! autovideosink

And of course you can resize the video and change the framerate:

gst-launch-1.0 -v \
    filesrc location="$SRC” ! \
    decodebin ! videoconvert ! videoscale ! video/x-raw,width=100 ! videorate ! video/x-raw,framerate=5/1  ! \
    autovideosink

Here's a more complete example, that keeps the audio, and changes the size and framerate:

gst-launch-1.0 filesrc location=$SRC ! \
    qtdemux name=demux  demux.audio_0 ! queue ! decodebin ! audioconvert ! audioresample ! \
    autoaudiosink \
    demux.video_0 ! queue ! \
    decodebin ! videoconvert ! videoscale ! videorate ! \
    'video/x-raw, format=(string)I420,  width=(int)320, height=(int)240, framerate=(fraction)30/1' ! \
    autovideosink

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