Wednesday, August 31, 2011

Some notes on capturing video/audio with GLC

Some notes on video/audio capturing with GLC:
  • it's much faster then recordmydesktop, but limited to OpenGL apps, can't capture random desktop regions
  • fast enough for 1280x720 capture on my old computer
  • front buffer capture doesn't work for me, as it includes window borders and distorts the picture, backbuffer capture with "-b back" works
  • audio capture is a bit problematic, installing libsdl1.2debian-alsa, forcing SDL to use alsa with "-j" and killing pulseaudio however seems to have fixed that
  • "-s" captures instantly, otherwise press Shift-F8 to start capture
  • "-i" shows an indicator in the top/left corner when recording, if not given, there is no sign if it's recording or not
  • use "glc-play -i 1 pingus3.glc" to inspect what streams are in a recorded file
  • there are some more options to tweak the compression in glc-capture that I haven't tried
  • gamma in the videos recorded by glc looks wrong, the resulting video is to dark
Complete capture line for Pingus looks like this:

glc-capture -l /dev/stdout -v 3 -i -j -o /tmp/pingus3.glc -b back build/pingus -r opengl -d data/ -g 1280x720

For converting the capture into a regular format one can follow the instructions from the GLC Wiki.

Final video looks like this:



3 comments:

mbue said...

Are you using GLC on a 64bit system? If so, which one and how did you get GLC to run and/or compile?

Cheers,
Martin

Grumbel said...

Nope, I am using it on 32bit Linux. I used the glc-build.sh script provided at:

https://github.com/nullkey/glc/wiki/Install

That page also contains some additional info on 64bit.

mbue said...

Ok, thanks for the info.
I just wondered wh you got it to work so easily.

Yeah, I tried the 64-bit instructions already, but it doesn't really work for me. It seems glc isn't really prepared to be (easily) used on such a system :-/

The glc-build.sh script messes up somewhere because of 32bit stuff (need to look up the details).
I'll try to dig further to find the exact error.