[wdmaudiodev] Re: Windows Vista SP1 and 24-bit audio

  • From: "Daniel E. Germann" <deg@xxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 30 May 2008 16:31:10 -0500

Hi, Jeff.

Thanks for the quick reply!  I made sure my DataRangeIntersection handler
replied "SUCCESS" when MaximumBitsPerSample came in as 24.  Unfortunately,
there must be something else going on, because all the 24-bit formats are
still missing.

I tried returning the resultant wave format with both wBitsPerSample=24 and
wValidBitsPerSample=24, and also wBitsPerSample=32 and
wValidBitsPerSample=24.  Neither did the trick.  I'm making sure to compute
nBlockAlign and nAvgBytesPerSecond properly, and I'm updating
DataFormat.SampleSize to nBlockAlign.

The debug output looks like what I'd expect.  One example is:

  client range PCM 96000-96000 kHz, 24-24 bits, 2 channels
  my range         96000-96000 kHz, 16-32 bits, 2 channels
  negotiated PCM 96000 kHz, 24/32 bits, stereo

That means that with the stated pClientDataRange and pMyDataRange as input,
the resulting WaveFormat was nSamplesPerSec=96000, wBitsPerSample=32,
wValidBitsPerSample=24, and nChannels=2, and that the return was

But 96 kHz, 24 bits/sample does not show up in the control panel.

Like I said before, this driver is working fine on everything from Windows
2000 SP3 to Windows Vista RTM.

Can anyone from Microsoft shed any light on this?  What changes (validation,
error checking, ???) were made in Windows Vista SP1 that might prevent
24-bit data formats from showing up in a driver that's been working until
SP1 was installed?

Best regards,
Dan Germann
Digital Audio Labs

-----Original Message-----
From: "Jeff Pages" <jeff@xxxxxxxxxxxxxxxx>
Subject: [wdmaudiodev] Re: Windows Vista SP1 and 24-bit audio
Date: Fri, 30 May 2008 09:16:58 +1000

Hi Dan,

I had the same problem. Check your DataRangeIntersection handler and make 
sure it's not rejecting PKSDATARANGE_AUDIO requests with 
MaximumBitsPerSample set to 24. Although the WDK documentation (under "PCM 
High Bitdepth Stream Data Range") says that MaximumBitsPerSample is set to 
the container size (in this case 32 bits), Vista doesn't.

In my case it appeared that the RTM build of Vista ignored my 
STATUS_NO_MATCH return, but SP1 didn't and therefore disallowed all 24-bit 
formats. Once I made my DataRangeIntersection handler accept a 
MaximumBitsPerSample value of 24, everything was sweet.

Jeff Pages
Innes Corporation Pty Ltd

----- Original Message ----- 
From: "Daniel E. Germann" <deg@xxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Friday, May 30, 2008 7:29 AM
Subject: [wdmaudiodev] Windows Vista SP1 and 24-bit audio

> We've had several customers report that after installing Windows Vista 
> SP1,
> all the 24-bit formats disappear from the Advanced tab for our devices in
> the Sound control panel.  We checked, and sure enough, all the 24-bit
> formats that used to be there with RTM are gone with SP1.
> Is there anything that would have changed with SP1 that would cause this?
> Thanks,
> -Dan
> --
> Dan Germann
> Digital Audio Labs


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