Fix audio input gets muted after a while on android

[AndreiPetrov890]

Fix the buffer underrun situation, which leads to unexpected mute of mic input in android application.

Original bug report: (#86428)

I personally encountered the same problem on my own project.

My solution is to delete mixed_frames correction in AudioStreamMicrophone. In other places of code this correction is used as sign of end of sound source (melody or recordings). But it's mic, folks. Mic stream must work until I stop it by myself, recording ambient sound. So no need to check the end of sound source. Mic source have no end.

Big thanks to @leoyanis, who ponts to problem, and great thanks to @kus04e4ek, who points to roots of the problem.

• Bugsquad edit, fixed: Audio input gets muted after a while on android #86428

[AThousandShips]

See also:

• Make AudioDriverOpenSL's input callback thread-safe #92969
• Make AudioStreamPlaybackMicrophone::_mix_internal be able to run at the same time as input callback for AudioDriverOpenSL #93154

There's already two open PRs for this, and it seems to be threading related

[kus04e4ek]

I don't really like this approach, if this code gets triggered, that means that AudioStremPlaybackMicrophone tries to read data that's not yet written (at least that's when this code is supposed to be executing), this should never happen and if it does that means that safety measures against it should be rethought (input buffer size and playback_delay) or AudioDriver implementation does something wrong. This was however triggered not by the AudioDriver implementation being wrong or safety measures not working, it was triggered by this: #93125. I think this check should stay, as otherwise reading from the input buffer would randomly fail and you would hear silence for a second, which is not ideal. In the PRs AThousandShips linked I added an error message if something like this happens, IMO users should report the error message and not silence, if something goes wrong

[AndreiPetrov890]

if this code gets triggered, that means that AudioStremPlaybackMicrophone tries to read data that's not yet written (at least that's when this code is supposed to be executing), this should never happen

100%, dude!

I guess this happens occasionly due to noise suppressor working in android, which stops recording instead of recording silence. I'm not sure, but that might be the case.

However, this patch works in my project and anyone can use it until a new version of the engine comes out, which I hope will include your patch for this issue.

Best regards!