Bug Report Xcomposite slows down window frame rate

[tacchinotacchi]

Hi all. I'm on Arch Linux, KDE on KDM, I game with bumblebee and nvidia binary. i open games with primusrun and obs with intel card.
I noticed that when I capture a game's window with Xcomposite and set Obs framerate to 30, the game looks like going at 30 fps. The game engine actually shows more fps (eg. 120 fps on osu!) but the game looks 30. This is probably not a performance issue, more like the composite manager limiting the frame rate to the rate at wich obs checks. So a 120 fps stream is ready but only shows 30.
I cloned git and the code seems fairly easy. Now it's 00:03 in my country and I'm not mentally capable of reading code, but tomorrow I'll give an eye too it and look for the problem (if it is a problem)
I'll update, the thread, but if you have a solution or want to help/discourage me, please reply.


The first solution that comes into my mind, is to make the Xcomposite plugin check as many times as the screen refresh rate (or maybe with a personalized tick) and then only give to obs the correct fps count (eg. 30)
Thanks in advance.

 

[ubuntuaddicted]

not sure what your goal is? you have a choice in which FPS you want to stream to the world but if you aren't partnered it's pointless to try to stream 60FPS (some may argue this point) because viewers will only be getting the stream from 1 server. I suggest setting your stream to 1280x720@30FPS. that's what your viewers will see. if you're using kde it has a built in compositing engine called kwin but that gets disabled when you fullscreen a game to the best of my knowledge. sadly i don't know the caveats of the whole bumblebee thingimajigger so I can't help ya there. i've just been told in the irc channel that obs captures at teh same FPS that you're outputting. so despite the game playing at 120FPS let's say, obs is only capturing 30FPS and that's what it will stream out as well.

 

[tacchinotacchi]

I did some other test and it was probably placebo. I was feeling that FPS was being capped to OBS framerate, but know that i have read the code and know for sure there is no part of it that caps FPS, and don't have that feeling anymore.
I guess I am human too :P