distorted audio on Apple devices

[richard-vd]

In recent releases of Apple software (macOS Big Sur using Safari 14.0.1, iOS 14.2 and iPadOS 14.2) the audio of my RTSP stream starts heavily distorted when using WebRTC (Opus audio). After some time audio becomes clean but it can go back to the distorted state later on. I already tried changing from stereo to mono audio and using a low audio bit rate, but it makes no difference. It does not happen when using MSE or HLS.

Older Apple software works fine, and other browsers on macOS Big Sur work fine too (Firefox, Chrome).

Could it be that the timestamps on the audio are a little too early? I have a feeling that tweaking the PTS offset on the Opus audio encoder might improve this.

I can share the URLs privately.

 

[Max]

Similar bug is reported for iOS 14.2:

218762 – Stuttering audio from WebRTC in iOS 14.2

bugs.webkit.org

No workarounds found for now. Waiting for webkit fix.

14.0.1 should work. You can try to increase Opus bitrate on server.
Won't help for 14.2 though.

opus.encoder.bitrate=64000

 

[richard-vd]

That's exactly the issue I have, thanks for pointing me to this bug report. The test case provided there is spot on: https://jsfiddle.net/juberti/bnmfvjo0/

 

[richard-vd]

Looks like they're on it: Safari Technology Preview 116 is generally okay!
Only right after starting the stream there is still a brief moment of this distortion, after that it remains stable.

 

[Max]

Looks like they're on it: Safari Technology Preview 116 is generally okay!
Only right after starting the stream there is still a brief moment of this distortion, after that it remains stable.

Good news, waiting for them to release the fix.

 

[richard-vd]

This issue has been fixed in macOS Big Sur 11.1 (Safari 14.0.2), iOS 14.3 and iPadOS 14.3.

 

[Max]

This issue has been fixed in macOS Big Sur 11.1 (Safari 14.0.2), iOS 14.3 and iPadOS 14.3.

We confirm audio distortion issue is resolved while playing WebRTC with Opus audio in these browsers.