Bug Report OBS periodic heavy stutter while capturing a video in a browser window, even when not recording

Dlfade

New Member
My goal is a little bit not orhodox because I'm trying to record video from a browser window. The problem I have is that everything is fine for a while, then I get very heavy stuttering. This stuttering appears in OBS preview window and of course the output video I might record. But the video playing in the browser is instead always smooth.

So it's OBS that starts to lag on its own. It seems to do this regularly. In general it was half an hour, then it stutters for two minutes, and then it fixes itself for another half an hour.

I'm trying to capture video at 25 fps. So I noticed that the only way to have it play smoothly, I have to set my monitor to a similar frequency. I made custom refresh modes, both at 25 and 50 Hz. And they both produce the same output, in what I see in the browser, and the video OBS is recording. So everything's working great. I tried setting OBS at 25 and 50 fps, matching the monitor refresh. No changes.

But again, I have this periodic stutter coming and going. Consider that I started with OBS Classic, and using window capture. I tried EVERYTHING. I messed with all possible settings. I changed the buffering value, I swapped from NVENC to x264. And then I even tried using monitor capture and use a second monitor.

Then I tried the new OBS. And in the meantime I also changed the videocard, from a GTX 770 to a 1080. And I tried ALL browsers.

None of these changes had ANY effect on the stuttering I'm having. CPU oscillating between 8 and 15%, and as I said I have stuttering even while I'm not recording. Just by looking at the preview.

Here's the deal: it seems that for some reason OBS "desynchs" itself from its source. Window capture or monitor capture are the same. I can see the video playing smoothly in the secondary monitor, while it stutters like crazy inside OBS. For a couple of minutes, then everything resynchs. Since this stuttering is happening because of something going wrong between the source and OBS, the problem for sure isn't about recording and encoding. It's OBS not capturing/synching well with the source. No background process using CPU or something like that.

TL;DR
I'm trying to capture the monitor or window output: a browser window playing a video. The video plays smoothly in the secondary monitor, but it periodically stutters heavily in OBS. It's as if OBS doesn't hook well with the source and de-synchs itself periodically for a minute or so. I tried many combinations of monitor refreshes and FPS values in OBS. The only way to have a smooth video is to set OBS at 25 FPS (the FPS of the source video) while setting the monitor refresh at a multiple of that value, so 25 or 50 Hz. Doing this produces a recorded video as smooth as the source video BUT every 15 or 30 minutes I get very heavy stuttering that goes on for 1-2 minutes before fixing itself. The problem is visible in OBS preview even while not recording, while the video in the browser is playing smoothly at the same time.

The only weird thing that seems having some kind of effect on the stuttering is if I open another window capture and begin checking unchecking the "multi adapter compatibility option". I only have one videocard, so this option should have no effect. It also doesn't fix any stutter, whether or not is checked. But *while* it is stuttering it seems to interfere a bit.
 

Dlfade

New Member
Not even a hint about where the problem is?

I noticed that the periodic stuttering shows already in OBS "source window", so it's not happening in the transition from source -> preview.

So I have, the actual program window that is smooth on a secondary monitor, and OBS "source" view of the same window that periodically stutters.

I simply don't understand how it's even possible.
 

Dlfade

New Member
Still trying.

It easy to test but requires time due to the fact the stuttering happens in intervals of 15 minutes or so (and lasts 1-2 minutes).

You just need to put this on a browser:
https://www.vsynctester.com/

Then capture with obs, no need to record, just look at what Obs produces on screen (the stutter happens both with window capture and monitor capture). Monitor set at 50Hz, Obs set at 25 fps. Naturally it's less smooth on Obs, but regular.

Then, when you hit the interval, you can see heavy stuttering within Obs, in Obs source and preview windows BOTH. But if you switch to the browser window when this happens you notice there's no stuttering going on (and I verify this with a secondary monitor).

The stuttering always starts with a few skips, then it gets progressively worse, and then it again decreases until it disappears. It's a regular pattern.

The stuttering is not browser related, or hardware acceleration related. It happens exactly the same in Firefox, Edge or Chrome. It's just about how Obs hooks onto the source, that produces this intervals of heavy jitter.

Isn't there any way to contact a developer who knows how the program works rather than users who obviously don't seem familiar with this? Any way to report the bug that isn't /dev/null?
 
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