https://github.com/pauloimon/gnome-screenshort-cut-extension
https://github.com/EasyScreenCast/EasyScreenCast
$sudo apt install ffmpeg
$pactl list sources short
$ffmpeg \
-f pulse -i alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
-f x11grab -r 30 -s $(xdpyinfo | awk '/dimensions:/{print $2}') -i :0 \
-c:v libx264 -preset superfast -crf 23 \
-c:a libopus -b:a 128k \
-pix_fmt yuv420p \
~/recording.mkv
ffmpeg -i incomplete.mkv -c copy complete.mkv