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Question about target FPS for recording with OBS

Posted: Mon, 22. Apr 24, 02:41
by user1679
Specs: My system at the moment is CPU bound. I have an RTX 3060 12 GB with an i5 7600 on a B-series board (soon to be upgraded to an i5 1300 and a Z-Series board) and my monitor is a 144 Hz 1080p screen.

I have OBS set to record at a bitrate of 5000 kbps and a constant 30 fps but with the 6.20 update and tweaking some mod settings I am able to reach 50 fps in game (with dips to between 32 and 40 in moderately busy sectors). I understand that recording at a constant 60 fps is obviously going to make the file size larger (though I use nvenc_hevc to offload the work to my GPU) but what happens if I set the recording to 30 fps and I see several minutes of game play at 40 or 50? I realize that extra data will be "lost" but forcing a constant 60 fps would simply be duplicating frames.

So, ignoring file size, would 30 fps with occasional discarded frames produce a smoother / better looking video than 60 fps with often duplicated frames, considering the duplicated frames are not an even multiple of 30 fps (eg: 50 fps only needs 10 duplicated frames to reach 60 fps).


NOTE: I am not streaming, just recording so I can later look for some fun screenshots (maybe).

Re: Question about target FPS for recording with OBS

Posted: Mon, 22. Apr 24, 02:57
by TroubledRabbit
I would use something lighter for pure recording, on Linux there is Simple Screen Recorder (and command line tools) on WIndows I have no idea.

If tweaking the settings is not an option for you - for the recording I would force stable fps in Vulcan (or MangoHUD or whatever you are using) at the desired rate (e.g. 30fps or any multiplicator working).

Re: Question about target FPS for recording with OBS

Posted: Mon, 22. Apr 24, 04:08
by user1679
TroubledRabbit wrote:
Mon, 22. Apr 24, 02:57
I would use something lighter for pure recording, on Linux there is Simple Screen Recorder (and command line tools) on WIndows I have no idea.

If tweaking the settings is not an option for you - for the recording I would force stable fps in Vulcan (or MangoHUD or whatever you are using) at the desired rate (e.g. 30fps or any multiplicator working).
I have two frame limiting options: the nVidia control panel or RTSS which I use with Afterburner to control my fans. I've heard the nVidia limiter can cause micro stutters.

Re: Question about target FPS for recording with OBS

Posted: Mon, 22. Apr 24, 13:52
by TroubledRabbit
for that someone much more familiar with NVidia gimmicks and WIndows shenanigans needs to answer.

In general: the option preferred should be that with the smallest footprint in the system - in theory that should be the drivers (because te game itself does not allow to set fixed fps target which would be the best option). Quality (e.g. fps variance, latency) is the secondary issue to puzzle out after.

Re: Question about target FPS for recording with OBS

Posted: Tue, 23. Apr 24, 06:00
by user1679
TroubledRabbit wrote:
Mon, 22. Apr 24, 13:52
for that someone much more familiar with NVidia gimmicks and WIndows shenanigans needs to answer.

In general: the option preferred should be that with the smallest footprint in the system - in theory that should be the drivers (because te game itself does not allow to set fixed fps target which would be the best option). Quality (e.g. fps variance, latency) is the secondary issue to puzzle out after.
I set the nvidia driver to 30 fps but it made the game completely unplayable. I ended up with an average fps of 18 and input lag was really bad. I decided to leave the game with no vsync and no external frame limiter, then recorded a few 5 minute videos. The videos seemed to play fine, I didn't notice any jitter or frame skipping, and the game was relatively stable.

I guess the recording algorithm must dither the frames it drops instead of just ignoring the last 12 frames. Having edited a few videos in my life, cutting out 12 consecutive frames leaves a noticeable jump.

Re: Question about target FPS for recording with OBS

Posted: Thu, 25. Apr 24, 03:57
by TroubledRabbit
happy got your job done.