Ubuntu 20.04: Device open failed

[gizmo69the2nd]

/dev/video10 is dummy device
sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="OBS Cam" exclusive_caps=1

ffmpeg is able to sink data to /dev/video10
ffmpeg -loop -re -i 2020-09-30\ 14-39-10.mkv -f v4l2 /dev/video10

OBS fails to open the device.
OBS user is the same as ffmpeg user and has permissions to RW /dev/video10

v4l2loopback installed from source and via apt-get, both give the same error

Any help is appreciated.

[ramonfontes]

Same problem here. It stopped working after upgrading the kernel to 5.8.

[tyoc213]

IOn ubuntu with sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="OBS Cam" exclusive_caps=1

modprobe: FATAL: Module v4l2loopback not found in directory /lib/modules/5.4.0-53-generic

[ochen1]

To solve modprobe: FATAL: Module v4l2loopback not found in directory

you have to recompile the v4l2loopback after upgrading kernels

cd ~/Downloads/v4l2loopback && make clean && make && sudo make install
(assuming you downloaded it to Downloads)

And then, you have to copy it or ln -s to /lib/modules, like this:

sudo cp *.ko /lib/modules/$(uname -r)

[ochen1]

and, btw, @tyoc213 im pretty sure you have a totally different problem, not what the OP is having difficulty with. and your issue has already been adressed by others

[ochen1]

@gizmo69the2nd I advise you to manually compile instead of using apt :)

[computer-wizard]

make installs installs the module in /lib/modules/$(uname -r)/extra
You have to run the command 'sudo depmod' afterwards, otherwise it doesn't see it!. (depmod creates modules.dep & map files)
Just copying to /lib/modules/$(uname -r)/ doesn't help. It has to be registered in modules.dep with the sub-directory it is in.
See the man page for depmod. (Tested at Ubuntu)

[ochen1]

Haha, sorry my bad.

Forgot to mention to run a sudo depmod -a afterwards lol

[gizmo69the2nd]

@gizmo69the2nd I advise you to manually compile instead of using apt :)

Can confirm that this works!
Thanks for the support.