Install V4l2 Loopback
GitHub – umlaeute/v4l2loopback: v4l2-loopback device

NB: On Debian/Ubuntu, works best to install the package v4l2loopback-dkms

$ sudo apt-get install v4l2loopback-dkms

Once installed, you should load the virtual cam.
First check which video devices you have.
$ ls -l /dev/vidoe*

For instance on mine I had /dev/video0 to 4 so I then create a virtual cam on 5 using :

$ modprobe v4l2loopback video_nr=5 card_label=“Virtual cam”

Add OBS plugin for loopback output : obs-v4l2sink

NB: Not working yet.

Clone obs-v4l2sink

(If you wanna try without the plugin: check the convo Hello CatxFish… Any way to install OBS-virtual-cam on ubuntu? · Issue #17 · CatxFish/obs-virtual-cam · GitHub )

cmake -DLIBOBS_INCLUDE_DIR="…/…/obs-studio/libobs/" -DLIBOBS_LIB="…/…/obs-studio/libobs" -DCMAKE_INSTALL_PREFIX=/usr …