Ubuntu 20.04 Virtual Camera is blank

[teledyn]

Everything seems to be in order, I have obs-studio 26.1.2, v4l2loopback-dkms and disabled the MOK in my bios, modprobe loads the loopback without complaining

$ v4l2-ctl --list-devices
Dummy video device (0x0000) (platform:v4l2loopback-000):
/dev/video3
$ ls -l /dev/video3
crw-rw----+ 1 root video 81, 3 Apr 16 16:27 /dev/video3

just in case obs can't write to video3, I also added my user to the 'video' group but it didn't help.

the log simply shows:
info: Virtual camera started
info: ==== Virtual Camera Start ==========================================

but when I go into zoom.us/test, I can select 'dummy video device', but there is no video; if I go into meet.google.com, it shows three of my 5 cameras (I'm experimenting with advanced switcher!) but does not show the dummy device, and I get the same behaviour in Chrome and Firefox. The only suspicious item that stands out in the console log doesn't seem relevant:

[swscaler @ 0x558f2ff6e680] Warning: data is not aligned! This can lead to a speed loss

Is there something I am forgetting to do?

 

[teledyn]

Oh, could it be something about zoom and meet? I just tried https://appr.tc/ and it proves my virtual camera is fine.

 

[Tuna]

Try one of the common camera resolutions first. 852x480 seems uncommon and apps may not support/ignore the virtual camera then.

 

[teledyn]

Try one of the common camera resolutions first. 852x480 seems uncommon and apps may not support/ignore the virtual camera then.

That was exactly right, thanks! I don't know where it got that aspect, maybe from my laptop screen, but switching canvas and output aspects to a 16:9 solved it.