obs: depend on v4l2loopback for virtual camera support

[larsgrah]

Testing the changes

• I tested the changes in this PR: YES

This dependency enables virtual camera support

[lemmi]

I'm not a fan of including v4l2loopback as a dependency. Since it is a dkms module, it pulls in a whole bunch of other stuff like gcc and linux-headers that not everybody necessarily needs. Also installing v4l2loopback alone won't magically make virtual cam work. You still need to load the module and configure it. At that point you already need to know enough that I would assume installing a package manually shouldn't be too hard a task.
At the moment this doesn't have my support, but I'm open hearing other opinions.

[larsgrah]

Not entirely sure what you mean, when installing v4l2loopback the modules got configured automatically for me. In what setup would that not work? After starting obs after installing it, virtual camera worked ootb

[lemmi]

I quickly checked again and the module isn't loaded for me by default as far as I can tell. I'm also not sure whether adding exclusive_caps=1 is still required for it to show up in chromium. So no ootb experience for me and the other point of quite a large number of dependencies remains.

[larsgrah]

Hm, unfortunately i cannot reproduce your experience. Currently unsure why it would not be loaded after being installed.

FWIW https://bugs.archlinux.org/task/69918 on arch it is included, not sure if xbps has the concept of optional deps though https://archlinux.org/packages/community/x86_64/obs-studio/

If its not merged based on the added deps its fine too i think, since its easy to solve the problem by manually installing the pkg. Just a bit confusing why the button for remote camera was missing.

[lemmi]

Sadly we don't have optional dependencies, it would definitely be the right use case here. Maybe upstream could be convinced to display an error or hint that the module needs to be installed and loaded for virtual cam to work. Most we can do is display an install message, but I doubt it has the necessary visibility to justify the added spam.
For the moment I considered this closed. Still, thank your for your effort.