WASAPI shows only 1–2 channels for custom USB Audio Class 1.0 microphone on Windows with 4 channels

Audacity 3 Help Forum Windows
1

Hello,

I am testing a custom USB Audio Class 1.0 (Full-Speed) microphone device on Windows. The device is correctly detected by Windows and appears as a multi-channel microphone in the Sound Control Panel, but when using Audacity with the WASAPI host, only 1–2 input channels are visible and recording cannot be started.

I would like to understand whether this limitation is expected behavior on the Audacity side or the Windows WASAPI side. In particular, does Audacity rely strictly on the WASAPI device format exposed by Windows, even if the underlying USB audio device supports more channels? Are there known limitations in Audacity/PortAudio regarding UAC1.0 Full-Speed multi-channel microphones on Windows?

Additionally, are there any specific requirements (such as mandatory control support or format negotiation behavior) that Audacity expects in order to open a WASAPI input stream successfully?

Any insight into how Audacity determines the available channel count for WASAPI input devices, or whether this is entirely controlled by Windows, would be very helpful.

2

From what I’ve seen here on the forum very few people are successful multitracking with Audacity.

I assume ASIO works better if you know how to compile Audacity with ASIO and you have a device with ASIO drivers.

3

Since Nov 2025 Audacity with ASIO compatibility is available … Download Audacity with ASIO – Leo Wattenberg

4

Cool!!! I read somewhere that ASIO licensing had loosened-up so I was wondering if that was coming. (I don’t have any ASiO hardware mysl e f e but it’s always been a missing feature.