OBS for Linux: Popping and clicking audio

[imrazor]

I’ve been trying to record (not stream) some WINE+DXVK & Steam Play gameplay with OBS for Linux. After some fumbling around, I manage to capture some video. However, there is a problem with the audio; there’s a lot of popping and clicking, even though in-game audio is crystal clear. I’ve put up one example here. It’s not totally horrible, but definitely noticeable.

Has anyone else run into this? If so, did you find any way to fix or at least lessen it?

[FurryJackman]

Got the same issue in GPU passthrough with Crash Bandicoot in a VM, Whenever a level loaded in the VM, my audio started cutting out in the recording. It happened with both Looking Glass and capture card capture regardless of NVENC or not.

This seems like an issue with the recent versions of OBS with heavy load situations. Remember that DXVK along with the multithreading of modern games can tax the CPU quite heavily.

This was my thread on my issues:

Audio dropouts on Pulseaudio capture on the host when the guest has high resource usage?

So with every other game I have tested in my GPU passthrough situation, none have interfered with the host when it’s recording/streaming using OBS… until now. Crash Bandicoot N. Sane Trilogy during load screens manages to use 90% CPU usage on the guest, and it finally caused my host’s Pulseaudio capture at 96000hz to start dropping samples. Tried hugepages in the host and core affinity in the guest to resolve it but it’s still there during loads… I wonder if this is at all common, so I want to conduct an experiment that I want people who own this game and use it in passthrough to try out: Play a 1Khz tone into the Line In of your sound card, which the host should be using. Set the sound card default formats to this in /etc/pulse/daemon.conf: default-sample-format = s32le default-sample-rate = 96000 Launch OBS and just record that input with the default settings, cause this is not testing video encoding CPU usage. Make sure the guest is running at the same time, then run a Crash NST loading screen. Play back the recording or import it into Audacity to see if it dropped samples. I’d be interested to know if using UMA on Threadripper might be able to solve this problem, and if it affects any other high core count CPUs with mitigation steps. A low level examination of the resource use would be helpful to find out why Pulseaudio drops samples ONLY DURING CAPTURE, because it can playback flawlessly when Crash NST is loading a level in the guest VM. I’m suspecting it might not be solely related to CPU because loading a Crash NST level also taxes the memory quite hard. Either that, or it’s a bug in OBS Git. If this is not happening with the default FFmpeg AAC encoder, might be a quirk with libfdk-aac. But I have used that fine for the last 6 months. I have noticed encoder overloads due to slow disk I/O, but even when it’s reading a level from memory, the issues happen, so I don’t think it’s disk I/O.

[imrazor]

@FurryJackman Interesting. I wouldn’t think CPU load would be an issue, since I have an 8C/16T CPU. I’ll try monitoring CPU usage next time I record. I should note that I experienced the static in Fallout 4 which I believe is not a heavily threaded game, so there should be a few free cores/threads for capturing/encoding video & audio. It should be noted that I am not using NVENC either. I tried with both the ‘fast’ and ‘veryfast’ presets @ 1080p/30fps and experienced the same effect at both settings.

There was absolutely NO problem with audio while playing the game(s). It’s only upon reviewing the recording that the audio issues are noticeable. I did try one native Linux game and did not notice the popping, but it wasn’t a very demanding game either.