[wdmaudiodev] Re: Windows 7 :: usbaudio.sys

  • From: "Daniel E. Germann" <deg@xxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Sat, 29 Oct 2011 07:36:50 -0500

Hi, t.

I have been able to successfully play and record under Windows 7 with our USB device, which packs 24-bit samples into 3-byte containers. There are artifacts due to a bug in waveIn/waveOut sample rate conversion, but if the application sample rate matches the sample rate set in the control panel, it works fine.


Unfortunately, the same device can play successfully on Windows XP, but the application gets erroneous data when recording if the device is opened in 24-bit mode. I tried packing the 24-bit data in both 3-byte and 4-byte containers, and the results were the same. The returned sample data is always 000000 or FFFFFF. If the application opens the device in 16-bit mode, valid sample data is returned in the record buffer. This is particularly confusing, since the device always sends 24-bit data.

Are you saying your device is able to play and record in 24-bit mode under Windows XP? If so, would you be willing to email me (off list) the USB descriptors you're using? We've been trying to figure out a solution for this because many of our client's customers still use Windows XP.

Thank you,

Date: Fri, 28 Oct 2011 13:10:46 -0700 (PDT)
From: -t <tge96@xxxxxxxxx>
Subject: [wdmaudiodev] Windows 7 :: usbaudio.sys


I'm wondering if you might know if usbaudio.sys in Windows 7 supports playback of 4-byte subframes with 24-bit resolution?

I have this topology working on my Windows XP 32-bit machine, and MacOS. However, for some reason Windows 7 is giving me mixed results. My record stream shows up in Sound, but my playback stream does not. The only thing I'm doing that's a bit not standard is 4B subframe. I'm planning to try with 3B subframe in the next couple of days or so, just to see if that works.

First, I'd like to confirm whether or not usbaudio.sys in Windows 7 support this topology or not?

Many thanks,


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