screencast | record-audio | record video | noise cancelation
we want a webcam overlay on the video stream. therefore we are simply opening a non-mirrored cam feed on the screen, which in turn, we capture with ffmpeg.
check available webcams
v4l2-ctl --list-devices
the easy way – however no aspect ratio
xawtv -randr -noalsa -c /dev/video0 &
the hard way
mplayer -really-quiet tv:// -tv device=/dev/video0 -vo xv tv:// &
this does not make it completely silent
# -msglevel all=-1
https://superuser.com/questions/361683/run-mplayer-from-bash-in-background-without-extra-bash
https://unix.stackexchange.com/questions/411617/webcam-xawtv-mplayer
https://raspberrypi.stackexchange.com/questions/29381/mplayer-doent-show-webcam
https://github.com/mpv-player/mpv/issues/852