Bug Report OBS 64-bit audio chirping issue [I figured it out]

[smite]

Myself and some other casters I've seen around here have been dealing with a high-pitched audio sound [example: https://obsproject.com/forum/threads/weird-audio-popping-noise.56918/ ]

I isolated an area of a game where I was able to reproduce it consistently and tried a variety of settings until I determined the following things about it:

1) OBS Classic works fine. It is OBS Studio causing the problem
2) Further, OBS Studio 32-bit works fine. OBS Studio 64-bit is causing the problem
3) The problem only occurs when the audio bitrate is below 224 kbps specifically, which unfortunately is higher than Twitch permits.
4) X264 or NVENC, CPU Usage... All of these other settings are irrelevant even though I initially suspected them. The only thing that fixes the problem is switching to OBS Classic, OBS Studio 32-bit, or using higher bitrate on the audio than twitch allows.

I haven't been able to reproduce this error under 32-bit OBS Studio, and am inclined to say that 64-bit's audio is the problem for some reason I don't know.

 

[c3r1c3]

That's very detailed. Thank you.

 

[RytoEX]

Can you also post logs? 224 Kbps is the point at which OBS switches to the FFmpeg AAC encoder from the Media Foundation AAC encoder on systems that don't have CoreAudio installed, so I'd guess it's something odd about 64-bit and Media Foundation. Can you reproduce it on 64 Kbps audio? Here's the AAC encoder bitrate mapping from an old log to show what I mean (from an older post of mine):

16:45:26.645: AAC encoder bitrate mapping:
16:45:26.645: 32 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)
16:45:26.645: 64 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)
16:45:26.645: 96 kbit/s: 'Media Foundation AAC Encoder' (mf_aac)
16:45:26.645: 128 kbit/s: 'Media Foundation AAC Encoder' (mf_aac)
16:45:26.645: 160 kbit/s: 'Media Foundation AAC Encoder' (mf_aac)
16:45:26.645: 192 kbit/s: 'Media Foundation AAC Encoder' (mf_aac)
16:45:26.645: 224 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)
16:45:26.645: 256 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)
16:45:26.645: 288 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)
16:45:26.645: 320 kbit/s: 'FFmpeg Default AAC Encoder' (ffmpeg_aac)

 

[smite]

We tried every bitrate of audio from 256 to 96 and had issues with all of the ones lower than 224 kbps. I didn't try 64 kbps because I wouldn't have been willing to go that low even if it solved this one problem.

As for logs, let's see if I can find one.

99% sure that the attached file is one example from when it was not working correctly and doing that sound error.

 

[RytoEX]

We tried every bitrate of audio from 256 to 96 and had issues with all of the ones lower than 224 kbps. I didn't try 64 kbps because I wouldn't have been willing to go that low even if it solved this one problem.

As for logs, let's see if I can find one.

99% sure that the attached file is one example from when it was not working correctly and doing that sound error.

That log also shows that CoreAudio is not installed, which is in line with what I said earlier.

Well, 96, 128, 160, and 192 all use the Media Foundation encoder. I'm not really asking if you would be okay streaming or recording with 64 Kbps or suggesting that you should be okay with that. I just want to make sure that it's only bitrates in the range that Media Foundation covers as that would point to Media Foundation being an integral part of the problem, or the problem itself.

You can probably also solve the problem by installing CoreAudio, which supposedly provides better performance and better quality. You can check this spreadsheet for details on how to do that, courtesy of @Mroczny_Gustaw.

 

[c3r1c3]

CoreAudio is MUCH better then MF and FFMPEG.

 

[smite]

I got ya, I was just saying why I didn't happen to try 64 kbps. I'll try installing this stuff and see if it helps.

 

[smite]

Confirming that core audio seems to fix it too, as far as I can tell. Haven't been able to reproduce it after installing those things at 160 kbps audio on 64-bit OBS.

 

[RytoEX]

Confirming that core audio seems to fix it too, as far as I can tell. Haven't been able to reproduce it after installing those things at 160 kbps audio on 64-bit OBS.

I would imagine not. Once CoreAudio is installed, it takes over audio encoding for all bitrates. If you wanted to see if Media Foundation was related to the issue by testing the lower bitrates, you'd have to do it on a Windows system that doesn't have CoreAudio installed.


Edit: I misread the post I was replying to and thought you were trying to reproduce at 64 Kbps after installing CoreAudio. For anyone wanting to test the lower bitrates without CoreAudio, my point is still valid, so I'll leave the information for others.

 

[Kaotika]

Wow, talk about luck. So I was doing a bit of digging and found this software. I have been looking for something like it for a very long time honestly just not for video games. I was looking for something like this to build some product demo's for work. Now that I found this software I do believe my time at work will be much more efficient. On top of that, being able to locate a solution to the audio pop issue quickly has made my opinion even better of OBS. Bravo to the dev team and the community. I will be using this at work, which will save money for our little non-profit as well as for my side business AND my YouTube Gaming channel. Thank you to everyone here in the community and to the devs of OBS.