Hi, I have a question for the usbaudio class driver.

 

We have a 2 stereo pair input/output usbaudio class compliant device, and we are seeing a weird problem on the WDM side, on WinXP SP2.  When an external stereo input is connected to our second stereo pair input (channels 3-4, 1 indexed), we are recording a signal using sndrec32 and other simple WDM based software.  But I know that these software packages are using WAVEFORMATEX and NOT WAVEFORMATEXTENSIBLE calls, so I would not expect anything except on channels 1-2 to be recorded.  Since I did not write the WDM driver, I can't say this for a fact, but when I had worked on portcls style drivers in the past, I noticed that these basic applications only recorded on channels 1-2.

 

I've only worked on the ASIO side of this device, not WDM.  I'm pretty sure this is not a hardware issue, because using my ASIO drivers we cannot duplicate this issue at all.

 

Can anyone explain this behaviour?  Why would the usbaudio driver output a mix of all the stereo inputs?

 

thanks,

 

Philip Lukidis