OBS Studio
OBS Studio is “free and open source software for video recording and live streaming.”
Main website:
Source Code
OBS Studio is available in many GNU/Linux distributions and also available on their website.
To get the source code for OBS and other dependencies:
git clone --recursive https://github.com/obsproject/obs-studio
git clone --recursive https://github.com/paullouisageneau/libdatachannel
git clone https://github.com/exeldro/obs-downstream-keyer