trwnh
### Description:
  • Using an audio interface with a mono input plugged into Channel 2 leads to no audio being detected by VRChat. Every other application works fine -- it is
    only
    VRChat that has this issue. In general, it seems that the downmixing to mono is causing the issue.
### Proposed solution
  • Downmix correctly using both stereo channels instead of only the left channel.
### Testing Environment:
  • OS: Windows 10, Windows 11
  • Audio device: Steinberg UR12, MOTU M4, Yamaha MG16XU
  • Other applications: Discord, OBS, Mumble, Telegram, Firefox, Windows Audio Settings
### Wiring:
  • Typical setup: Mono XLR microphones wired into Channels 1, 2, 3 of the MG16XU analog mixer, plus stereo line 1/4" TRS inputs wired into Channels 9-10, 11-12, 13-14, plus USB audio from the PC into Channels 15-16. The microphones from Channels 1, 2, 3 are also sent out to AUX 1, which is connected to Channel 2 of the Steinberg UR12 via a mono 1/4" TS cable.
  • Minimal setup: Mono XLR microphone wired into Channel 2, then Channel 1 of the MOTU M4 digital interface.
### Further details:
  • I'd rather not buy new hardware or rewire my analog setup just because VRChat is incorrectly downmixing my mic input while every other application I've tested has worked flawlessly.
  • It just works on Linux. I assume Pipewire is downmixing properly before it reaches VRChat. No such luck on Windows.
  • As a workaround, you can use something like Voicemeeter to downmix to mono, then use a virtual output to wire it into a virtual audio cable. But it would be nice to have this working natively in VRChat.