OBS won't use camera unless another program uses it first

[d4hines]

I'm getting some odd behavior where OBS won't use my web cam at first (no LED indicator light, just a black box shown for the output of the camera). Only after I close OBS and open another program that uses the camera (specifically I've been using Google Meet on Google Chrome) will the camera start working. I then close the browser and open OBS, and it displays the camera output as expected.

It happens every time. I've captured the logs here: https://gist.github.com/d4hines/88f78ae74b21674f5bb869a4c80a7b80 The two files correspond to the first (unsuccessful) and second (successful) runs of OBS.

I'm running Arch Linux, with OBS 27.1.3. I posted about it on Github but the devs say it's not a bug. I suspect there's some extra setup that Chrome does that OBS does not do - perhaps the initialization of some driver or daemon. I'm not sure where to start looking for such a thing though.

Any advice would be appreciated.

 

[d4hines]

I made some progress on this. I noticed that when I go to the video capture settings in OBS and change the video format from it's default to BGR3 (emulated), the video works. In fact, it then continues to work after that for other formats. I'm not sure whether leaving it set to BGR3 is a sufficient fix. This was a clue that led me to this blog post: https://jpetazzo.github.io/2020/06/27/streaming-part-4-linux/, which mentions issues similar to mine.