4.2 KiB
Basics (GStreamer command-line cheat sheet)
Playing content
These examples assume that bash variable SRC to be set to a video file (e.g. an mp4 file). You can do this by, e.g.
export SRC=/home/me/videos/test.mp4
Play a video (with audio)
The magical element playbin can play anything:
gst-launch-1.0 playbin uri=file://$SRC
This works with video, audio, RTMP streams, and so much more.
The 'bin' in 'playbin' means that under-the-hood, it's a collection of elements. We could split it down into the individual components:
gst-launch-1.0 filesrc location=$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=$SRC ! decodebin ! tee name=t ! queue ! audioconvert ! wavescope style=color-lines shade-amount=0x00080402 ! alpha alpha=0.5 ! videomixer name=m background=black ! videoconvert ! vertigotv ! autovideosink t. ! queue ! audioconvert ! spacescope style=color-lines shade-amount=0x00080402 ! alpha alpha=0.5 ! m. t. ! queue ! autoaudiosink
Add filters
Here's the 'vertigo' filter:
gst-launch-1.0 -v filesrc location="$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)
Add a clock
gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! clockoverlay font-desc="Sans, 48" ! videoconvert ! autovideosink
Resize video
gst-launch-1.0 -v filesrc location="$SRC" ! decodebin ! videoconvert ! videoscale ! video/x-raw,width=100 ! autovideosink
Change framerate
Changing framerate is quiet common, as the world does not have a consistent standard. Facebook Live wants 30fps, for example.
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
Play an MP3 audio file
Set the environment variable $AUDIO_SRC to be the location of the MP3 file. Then:
# All three of these do the same thing:
gst-launch-1.0 playbin uri=file://$AUDIO_SRC
gst-launch-1.0 -v uridecodebin uri="file://$AUDIO_SRC" ! autoaudiosink
gst-launch-1.0 -v filesrc location=$AUDIO_SRC ! mpegaudioparse ! decodebin ! autoaudiosink
Play files back to back
See (https://coaxion.net/blog/2014/08/concatenate-multiple-streams-gaplessly-with-gstreamer/)[https://coaxion.net/blog/2014/08/concatenate-multiple-streams-gaplessly-with-gstreamer/]
Jumping to a certain point in a video/audio (seek/rewind/restart)
As far as I know, this isn't possible on the command-line. But it is possible as code. Here is a simple Python example: