WASAPI with multi channel audio causes sync issue

[Loeher0629]

First and foremost consider this:

• Only RetroArch bugs should be filed here. Not core bugs or game bugs
• This is not a forum or a help section, this is strictly developer oriented

Description

WASAPI with multi-channel audio causes sync issue (about 75% underrun). If sound device is set to output 2 channels, the problem will disappear, everything is fine.

Expected behavior

WASAPI with multi channel audio with 0% underrun.

Actual behavior

WASAPI with multi channel audio with 75% underrun.

Steps to reproduce the bug

1. set audio device to output multi channels (ie. 5.1)
2. run any game with any core.
3. reproduce the bug.

Bisect Results

RetroArch 1.16 and newer

Version/Commit

• RetroArch: 1.19.1 Stable
• OS: Windows 11