[FFmpeg-user] kmsgrab on Intel 8th generation aka h/w accelerated screen capture

Kai Hendry kai.hendry at gmail.com
Mon Jun 25 04:10:29 EEST 2018


Hi ffmpeg users,

Sorry I initially posted my question here:
https://www.reddit.com/r/ffmpeg/comments/8tgejw/kmsgrab_on_intel_8th_generation_aka_hw/

Via https://trac.ffmpeg.org/wiki/Hardware/VAAPI#ScreenCapture I
discovered kmsgrab which astonishingly doesn't seem to drop frames or
over heat my T480s when recording my Xorg display!
Unlike when I record with x11grab & VAAPI:
https://github.com/kaihendry/recordmydesktop2.0/blob/vaapi/x11capture#L55
Also see: http://lists.ffmpeg.org/pipermail/ffmpeg-user/2018-March/039227.html
Same issue on ffmpeg 4.x btw:
https://s.natalian.org/2018-06-25/1529888878.mp4.log

However since kmsgrab requires CAP_SYS_ADMIN as it points out to its
friendly documentation
https://www.ffmpeg.org/ffmpeg-devices.html#kmsgrab I believe I need to
run it with `sudo`. However when I run it as `sudo` I hit a issue
accessing my pulseaudio microphone.
https://stackoverflow.com/questions/51007952/recording-pulse-audio-as-cap-sys-admin-with-ffmpeg

Any tips how to get this all working?
https://github.com/kaihendry/recordmydesktop2.0/blob/kms/x11capture#L54
is my branch of kmsgrab based screen capture cli.


Kind regards,


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