Streaming runs fine for a while, then FPS drops until Alt-tab to OBS and back

[Nightwolf23]

Been starting to get into streaming DCS World on Youtube and having an interesting issue, searched around and found a couple old threads with similar issues but the solutions didn't work for me. Basically the stream runs fine for a while (the less performance intensive the current game scenario, the longer it stays fine), and eventually the framerate in the game itself becomes laggy and stuttery. I can then alt-tab to OBS for a second or two and back to the game, which fixes the framerate and the timer starts again. This is happening at multiple resolutions and bitrates, streaming to Youtube and I think also during recording.

I've tried different process priorities, running OBS as admin, putting it on the same screen as DCS, using display capture and game capture, and of course different resolutions and bitrates, but it still happens. My GPU is usually at 100% in task manager during gameplay, could this be the issue? I don't have any problems using Shadowplay to record, for example, even at much higher bitrates and full resolution and as far as I know that uses the same encoder. The game also runs fine and at full resolution when alt tabbed, it's not like it stops rendering... My temperatures seem under control according to HWInfo64 (CPU is boosting all the way and GPU temps are fine). Also, yes I'm streaming in non-16:9, but setting up a custom stream key makes it work on Youtube's end without adding black bars.

Log file of my most recent session is attached, any ideas are welcome

 

[Nightwolf23]

Tried another stream today, same issue. Log attached. I was checking task manager during it and noticed some interesting behavior. When it's running fine, the game is using up most (~90%) of my GPU, with OBS using ~5-6%. When I zoomed in on an intensive scene or sometimes just approached a more framerate heavy situation, the heavy lag in game starts, and OBS shoots up to ~50% usage with DCS dropping to take up the other 50%. Alt tabbing to OBS for a few seconds returns the game performance and the GPU utilization to the original 90% game 6% OBS.

 

[Nightwolf23]

Well I'm back again. Still happening, same deal with the symptoms. I've tried different encoding settings and different game settings, but still the same deal. I think it does have something to do with the GPU load, because it definitely happens faster in higher demand scenarios. Logs and the latest stream with a framerate + frame time counter is available (side note the audio buffering overload in the log is from the game loading in and lagging hard, didn't happen during the relevant part). I'm playing normally, the frame time doubles, and from watching task manager on my second monitor OBS suddenly starts eating half or more of the GPU. GPU temps stay around 60C the whole time. When I alt tab to OBS, within 10 seconds the frame times go back to normal, my framerate just about doubles (even with OBS still focused and on a second screen, the DCS framerate counter clearly shows 60 FPS), until I alt tab back into DCS for a few seconds to a minute.

I've tried running OBS as admin, changing its process priority, constant bitrate and CQP encoding, removing all other video sources from the scene, and putting OBS on the same monitor as the game. I've tried running the game with Vsync, in fullscreen and windowed, and running the game with lower settings (which helps but only delays the inevitable in the high demand scenarios). I've used shadowplay to stream a few times and it works perfectly the whole time, even with even higher settings. I know that the game is CPU limited due to its lack of multithreading, and like I said shadowplay always works fine for recording and streaming at higher qualities than I'm trying to use in OBS.

I'm running out of ideas. The game can clearly run at 60fps while OBS is streaming because it works great as long as OBS is focused and not DCS. For whatever reason it just can't handle me being focused on DCS while it happens. I haven't had this happen with any other game but I also haven't really played anything that's as resource intensive as DCS in terms of framerates achievable.

 

[JohnPee]

Have a look at the analysis output from one of your log files.

Analyzer | OBS

OBS (Open Broadcaster Software) is free and open source software for video recording and live streaming. Stream to Twitch, YouTube and many other providers or record your own videos with high quality H264 / AAC encoding.

obsproject.com