Using a virtual camera is a relatively common method to use a digital avatar as your webcam output. This is useful for example for streaming or for video calls where you don't want to show your face or you want to be identified as your digital avatar.

If you first open OBS Studio, put any source in it, trigger the Start Virtual Camera button, and then attempt to show your webcam on some website (like https://meet.kde.org or https://mozilla.github.io/webrtc-landing/gum_test.html), the virtual camera does not get detected.

This happens only when you use pipewire libcamera (the new default). This does not happen when you set media.webrtc.capture.camera.allow-pipewire to false.

Reproducible: Always

Steps to Reproduce:
1. Set up rpmfusion to get the necessary bits for virtual camera to work on OBS Studio (v4l2loopback)
2. Ensure the v4l2loopback is loaded
3. Open OBS Studio and create any scene
4. Click on Start Virtual Camera
5. Open a website that can record your webcam output
6. Check the available list of webcams available
Actual Results:
Virtual camera from OBS does not show up

Expected Results:
Virtual camera from OBS shows up

Additional Information:
I am using distro packaged Firefox and OBS. I tested this months ago as well and IIRC this also happens with the flatpak versions.

Additionally, if you already have something using your Webcam aside from OBS (like VSeeFace from WINE or the OpenSeeFace Python script) and then follow the above steps, you just don't get any available device at all, even though the physical webcam device is properly named in meet.kde.org and the webrtc test says Success.

I also have the following in ~/.config/wireplumber/wireplumber.conf.d/99-libcamera.conf to force libcamera:

wireplumber.profiles = {
  main = {
    monitor.v4l2 = disabled
  }
}

Relevant links:
* https://jgrulich.cz/2024/08/19/making-pipewire-default-option-for-firefox-camera-handling/
* https://jgrulich.cz/2024/12/13/when-your-webcam-doesnt-work-solving-firefox-and-pipewire-issues/
* https://www.vseeface.icu/ (to make it run you just create a WINE Bottle and put it inside the prefix then run it, you can use the default avatar to test)
* https://github.com/emilianavt/OpenSeeFace
* https://youtu.be/1URl-yS4UP8 (an example of myself using a digital avatar as webcam output)