[wdmaudiodev] Re: Windows 7, multi-channel, 16-bit, dither bug?

  • From: "David A. Hoatson" <dhoatson@xxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 28 Dec 2009 08:14:42 -0800

Posted bug with Microsoft Connect.

https://connect.microsoft.com/site148/feedback/ViewFeedback.aspx?FeedbackID=
522288

Thank you,
 
David A. Hoatson
Lynx Studio Technology, Inc.
www.lynxstudio.com
 

> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Frank Yerrace
> Sent: Wednesday, December 23, 2009 1:52 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Windows 7, multi-channel, 16-bit, 
> dither bug?
> 
> Yes, it can't hurt. This is (at least) the second report of 
> this kind I've heard on this list.
> 
> Frank Yerrace
> Microsoft
> 
> This posting is provided "AS IS" with no warranties, and 
> confers no rights.
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of David 
> A. Hoatson
> Sent: Wednesday, December 23, 2009 8:34 AM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Windows 7, multi-channel, 16-bit, 
> dither bug?
> 
> Frank,
> 
> Should I submit a bug report on this one?
> 
> Thank you,
>  
> David A. Hoatson
> Lynx Studio Technology, Inc.
> www.lynxstudio.com
>  
> 
> > -----Original Message-----
> > From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
> > [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of David A. 
> > Hoatson
> > Sent: Sunday, December 20, 2009 3:53 PM
> > To: wdmaudiodev@xxxxxxxxxxxxx
> > Subject: [wdmaudiodev] Re: Windows 7, multi-channel, 16-bit, dither 
> > bug?
> > 
> > Frank,
> > 
> > I am using our Lynx Demo app which I wrote.  It is using MME
> > (waveOutOpen) and the app doesn't touch the audio at all.  
> > Playing a 44.1kHz file and the hardware is also set at 
> 44.1kHz so no 
> > SRC should be occuring in Windows.
> > Our hardware level meters go to -114dB so I can clearly see 
> the extra 
> > bits getting messed with (shows -94dB, so I am seeing 20dB of noise 
> > above the threshold of the meters).
> > Since I wrote the driver & app and it is our hardware the 
> only part we 
> > don't control is between MME and WDM in Windows, which is of course 
> > why I made the post. :-)
> > 
> > We have not seen the same problem in Windows Vista, so it must be 
> > something new in Windows 7.
> > 
> > Thank you,
> >  
> > David A. Hoatson
> > Lynx Studio Technology, Inc.
> > www.lynxstudio.com
> >  
> > 
> > > -----Original Message-----
> > > From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
> > > [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of 
> Frank Yerrace
> > > Sent: Friday, December 18, 2009 2:54 PM
> > > To: wdmaudiodev@xxxxxxxxxxxxx
> > > Subject: [wdmaudiodev] Re: Windows 7, multi-channel, 
> 16-bit, dither 
> > > bug?
> > > 
> > > How are you playing the file? What application? Or if you 
> wrote the 
> > > application, what audio API family is the application calling?
> > > 
> > > Also, just curious, how did you notice this? What 
> tools/process did 
> > > you use?
> > > 
> > > Frank Yerrace
> > > Microsoft
> > >  
> > > This posting is provided "AS IS" with no warranties, and 
> confers no 
> > > rights.
> > > 
> > > -----Original Message-----
> > > From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
> > > [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of David A.
> > > Hoatson
> > > Sent: Friday, December 18, 2009 9:55 AM
> > > To: wdmaudiodev@xxxxxxxxxxxxx
> > > Subject: [wdmaudiodev] Windows 7, multi-channel, 16-bit, 
> dither bug?
> > > 
> > > Hello,
> > >  
> > > It appears that Windows 7 WDM audio sub-system has a strange bug 
> > > (feature?!?).  When in 16-bit multi-channel mode (I'm using
> > 5.1 for my
> > > testing), and playing back a stereo file, there is some 
> audio being 
> > > played back (at a very low level) on channels 3, 4, 5 & 6 when it 
> > > should be streaming zeroes.
> > > It is about 94dB down from the original signal, which leads me to 
> > > think that somehow the audio sub-system is applying dither to the 
> > > channels that should be playing silence.  I haven't tried this on 
> > > Vista yet, so I don't know if it does the same thing.  Windows XP 
> > > obviously doesn't do this.
> > > 24-bit mode works as expected.
> > > 
> > > Any ideas?
> > >  
> > > Thank you,
> > >  
> > > David A. Hoatson
> > > Lynx Studio Technology, Inc.
> > > www.lynxstudio.com
> > > 
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