sudo LIBVA_DRIVER_NAME=iHD ffmpeg -crtc_id 69 -framerate 60 -f kmsgrab -i - -vaapi_device /dev/dri/renderD128 -filter:v hwmap,scale_vaapi=w=1920:h=1200:format=nv12 -c:v h264_vaapi -profile:v constrained_baseline -level:v 3.1 -b:v 20000k test.mp4
LIBVA_DRIVER_NAME=iHD ffmpeg -device /dev/dri/card0 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -c:v h264_vaapi -vstats output.mp4
Unsafe but needed
sudo setcap cap_sys_admin+ep $(which ffmpeg)
Src: https://ffmpeg.org/pipermail/ffmpeg-user/2018-June/040338.html
https://github.com/ammen99/wf-recorder might be of help :)