[wdmaudiodev] USB Audio/WASAPI channel limits?

  • From: "Jerry Evans" <jerry@xxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Wed, 5 Feb 2014 18:27:04 -0000



I'm developing a USB2 input only audio device that exposes a large (N >= 24)
number of channels. 


The device is recognized and streams correctly on W7x64 at up to 32
channels, 48K sample rate and both 16 and 24 bit sample sizes. Data is
recorded accurately using various commercial WASAPI hosts (Sonar/Tracktion)


Windows, however, appears to baulk at any larger channel count. The various
USB tracers (both stack and wire) show Windows sending a QUERY_CAPABILITIES
every second or so when device is configured with 32 channels. Anything
above that and zero action.


Is there some hard limit or have I missed something?





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