I haven't specifically seen this issue reported, but I'm using OBS Studio to stream & record our Roll20 sessions. I haven't tried this when *just* streaming, but I see this behaviour when recording... When NOT recording, webcams work fine, I can see mine, others can see mine, I can see theirs. When recording, I can see mine, but not theirs. If I disable broadcasting my cam via Roll20, I can then see theirs, but I can't be broadcasting and receiving at the same time while OBS is recording. If I stop recording, the cams all work. I do NOT have my cam set as a video capture source in OBS, I have it all via Roll20. Has anyone come across this issue? I am using Firefox. I cannot use Chrome because in order to use Window Capture with OBS so I can mask the cams, I need to turn off hardware acceleration in Chrome, which makes Roll20 run like molasses, so stuck with Firefox.
I record all our sessions with OBS, and have not encountered this behavior. I run it with all sorts of setups. When not the DM, I use the web cam set as video capture for me, since the remote players and DM are all in the same room and prefer to use minis on a real table. In this case, I still use Roll20 to run my character but use Skype for video. When DMing, I usually have the feed all from Roll20, maybe with a vignette for the video windows so that they can be enlarged when not using the play surface. I typically am drawing video from anywhere from 1 to 4 sources. The only time I have noticed an impact on Roll20 performance turned out to be an issue with the PageFX script. This may have been been some bad synergy with OBS, causing too much processor resource drain, I don't know, but it stopped when I disabled the script.
Is PageFX a Pro thing, or a browser thing? I'm running Plus, though can't imagine that would have any bearing... Are you using Firefox or Chrome? And how are you pulling your cam sources for the other players? It just seems weird that when OBS is open and doing nothing, it works fine, but when I hit record, it craps on the Roll20 cams that aren't mine. Our DM has the bandwidth set to High.
Page FX is an API Script. Since it's the only thing that has undeniably impacted general performance, and I have stopped using it, I think we can ignore it. I use Chrome for running the game as the GM, and Firefox for a "Camera" account, so I can record the playfield as seen by the players. But I have recorded entirely within Chrome as a player. (I also frequently record just Skype, though I run Roll20 for my personally character sheet, but again, we can discount that, since I am not using Roll20 video for that). I have also used multiple feeds from one instance of Chrome or Firefox to vignette the video chat windows (so that I can make them larger for Theater of the Mind encounters). So long story short, I've used just about every combination of sources over multiple apps and browsers, and haven't run into the issue you are experiencing. I have run into all manner of breakdowns of both Skype and ROll20 video, as many people here have reported, but these seem to be unrelated to whatever OBS is doing. I've never had anything suddenly start or stop working when I've hit any control in OBS. One thing I have not done, and that is live streaming. I figure we deal with enough bandwidth issues