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Weird, worked pretty out of the box here besides some of the v4l2 parameters for application compatibility. My system is a bit outdated though, v4l2loopback-dkms 0.9.1-4ubuntu0.1 and OBS 24.0.3 (64 bit, installed through whatever the quickstart guide suggested for Ubuntu).

I'm using this to initialize the loopback device:

    #!/bin/bash
    set -e
    if lsmod | grep "v4l2loopback" &> /dev/null ; then
        echo "v4l2loopback is loaded"
        lsmod | grep "v4l2loopback"
        sudo rmmod v4l2loopback
    fi
    sudo modprobe v4l2loopback devices=1 video_nr=2 exclusive_caps=1
    lsmod | grep "v4l2loopback"

I think you led me to the problem. I updated the original comment, but I think the issue was that v4l2loopback was being loaded without any options and screwing me up, so rmmod ing it and reloading it seems to help

You can set default module options through a file in /etc/modprobe.d/. If you're using systemd, it can also be configured to load the module automatically on startup. This is what I'm using:

/etc/modprobe.d/v4l2loopback.conf:

    options v4l2loopback devices=1 video_nr=10 card_label="OBS Cam" exclusive_caps=1

/etc/modules-load.d/v4l2loopback.conf:

    v4l2loopback

Working flawlessly so far in Hangouts and Zoom using OBS Studio and the obs-v4lsink plugin.

Anyone else reading this post and wondering if it's worth trying, I was able to get it working on ubuntu 18.04 without much fuss, just followed this post[1] and compiled v4l2loopback from source[2] (needed to have version >=12)

[1] https://srcco.de/posts/using-obs-studio-with-v4l2-for-google...

[2] https://github.com/umlaeute/v4l2loopback/tree/v0.12.3

Some time ago I got it working with ffmpeg with raw video, but I'm afraid it got lost in bash history.

edit: Relevant section from my ~/.config/obs-studio/profiles/Untitled/basic.ini

    [AdvOut]
    TrackIndex=1
    RecType=FFmpeg
    RecTracks=1
    FFOutputToFile=false
    FFFilePath=/dev
    FFURL=tcp://localhost:55555
    FFFormat=rawvideo
    FFFormatMimeType=
    FFExtension=yuv
    FFVEncoderId=13
    FFVEncoder=rawvideo
    FFAEncoderId=0
    FFAEncoder=
    FFAudioMixes=1
    FFVCustom=
    Encoder=obs_x264
    FFVBitrate=15000
    RescaleRes=1600x900
    RecRescaleRes=1600x900
    FFRescaleRes=1600x900
    FFMCustom=
    FFVGOPSize=50
    FFIgnoreCompat=false

In the UI these stuff are set under Output > Recording, Type is "Custom Output (FFmpeg)". It did require some fiddling on the receiving side in my ffmpeg command line.

Did you try purging the dkms version and building the one in the post?

I also spent an inordinate amount of time messing with it, but in the end the actual steps that worked were simple. I couldn't get it to work with my flatpak version, and Debian stable is not fun trying to compile OBS (need more recent version of cmake).

But Ubuntu should be more straightforward... Did you get the option in the Tool menu yet? The other thing I got reading through all the GitHub issues was the need to sometimes change the YUV setting in that dialogue to YU2 (from memory).

Hope you get it cracked without much grief, and I can share what I can remember fwiw.

I did attempt purge DKMS, and confirmed the kernel module is the one I've just compiled.

I have it in the tool menu in OBS Studio. If I start the stream with RGB the camera doesn't work. If I start it with YUV32 as suggested in most guides, OBS just segfaults. switching it to YU2 was a helpful hint -- it just doesn't work as opposed to segfaulting.

Another quick thought, did you check you're using the right device? In that tool menu dialogue you could switch it to 0 instead of 1 etc or try grepping for the device list...

And can you view the device in VLC even when RGB? There are individual settings per input for RGB/YUV etc which I think default to the latter.

I updated the top comment, but you got me looking closer at the device list. It seems that v4l2loopback and my webcam were interfering with each other. rmmod-ing v4l2loopback, running the mopprobe myself, unplugging my webcam and plugging it back in seemed to resolve it.

Eyy, victory. Linux, the OS you love to hate. Wouldn't have it any other way.

Is your system running Wayland? I recall OBS screenshare wasn’t compatible with Wayland at all. I had to log out and log in using the X11 fallback to get it to work. It’s a rather unfortunate condition that past tutorials say “just do XYZ and it works” but they quietly assumed X11.

It's not the screenshare that's the problem, it's the v4l loopback to emulate a webcam

The joys of working with Linux ;)

I'm on RHEL. The install instructions for OBS Studio go on for paragraph after paragraph.