Cannot start virtual camera in OBS in Ubuntu 24.04.2 LTS on Acer Swift

[alanvoore]

When I press "Start Virtual Camera" a popup shows up saying:

> Starting the output failed. Please check the log for details.

Note: If you are using the NVENC or AMD encoders, make sure your video drivers are up to date.

I have attached the log file for reference. I am using Ubuntu 24.04.2 LTS on Acer Swift. I also tried installing

ffmpeg

using

sudo apt install ffmpeg

but that didn't solve the error. I have also tried changing output setting but that ddin't solve the issue either. So how can I solve this problem. For reference, I installed OBS using the following commands:

sudo apt install v4l2loopback-dkms
sudo add-apt-repository ppa:obsproject/obs-studio
sudo apt update
sudo apt install obs-studio

 

[Tuna]

Most likely https://github.com/obsproject/obs-studio/issues/11891

On the other hand.. does Ubuntu LTS bump v4l2loopback versions? Do you use secure boot?

 

[alanvoore]

@Tuna

When I try the command sudo apt install v4l2loopback-dkms , I get the following output:

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
v4l2loopback-dkms is already the newest version (0.12.7-2ubuntu5).
0 upgraded, 0 newly installed, 0 to remove and 8 not upgraded.

As you can see the v4l2loopback-dkms is already installed with version 0.12.7. Should I downgrad or upgrade that version. How should I proceed? Secure boot is enabled.

 

[Tuna]

Secure boot is probably your issue then. v4l2loopback module is not signed as you build is locally and therefore is rejected when trying to be loaded. Try loading the module manually and I expect it to throw an error.

 

[stephematician]

I don't think secure boot makes a difference when it comes to building and installing v4l2loopback, or loading it.

If you want to check that v4l2loopback works, try the terminal command `sudo modprobe v4l2loopback video_nr=10` (the last part isn't needed, but it means the device will appear at /dev/video10). If that succeeds, then try running OBS and starting the virtual camera. If you want to unload the v4l2loopback module, the terminal command `sudo rmmod v4l2loopback` will do the trick.

I tried to test the fix for this on as many platforms as possible, including with the 0.12.7 loopback module. So if it isn't working, then perhaps I'm not as clever as I think I am!

[EDIT]Also - which version of OBS studio are you using? 31.0.3? Try upgrading to at least 31.0.4 which has the fix I wrote applied. Or 31.1 which has just been released.[/EDIT]