I have successfully set up the virtual camera in OBS:
sudo apt install obs-studio v4l2loopback-dkms
sudo usermod -aG video myuser
The following versions are installed:
v4l2loopback-dkms 0.12.5-1
obs-studio 26.1.2+dfsg1-1~ubuntu20.10.1~ppa1
Kernel: 5.11.0-11-lowlatency
After a reboot, the virtual camera button and settings are showing up in OBS, and clicking the start button creates the following CLI output:
info: Virtual camera started
info: ==== Virtual Camera Start ==========================================
It also seems to work according to v4l2-ctl:
$ v4l2-ctl --list-devices
OBS Virtual Camera (platform:v4l2loopback-000):
/dev/video6
USB 2.0 Camera: USB 2.0 Camera (usb-0000:00:14.0-4.2):
/dev/video4
/dev/video5
/dev/media2
Integrated_Webcam_HD: Integrate (usb-0000:00:14.0-6):
/dev/video0
/dev/video1
/dev/video2
/dev/video3
/dev/media0
/dev/media1
After changing the refresh rate in OBS -> Settings -> Video to 30 fps, the virtual camera also shows up in Cheese, but selecting it there, Cheese can not use it and displays an error There was an error playing video from the webcam. Cheese does not create any CLI output.
In Zoom, the virtual camera does not show up in the selection menu at all.
I also experimented with different color format settings in OBS -> Settings -> Advanced, but to no avail, it doesn't affect the outcome.
Any idea what could be a reason?
[Update:] The virtual camera works when using VLC. This to me indicates a problem with the output format. However, I have tested all possible output resolutions, frame rates, and color formats offered by OBS, and none work with Cheese or Zoom.