[wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy

  • From: "Markus Bollinger" <bollinger@xxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 23 Jul 2010 14:34:17 +0200

Thank you Jeff for your pdf file.
I think I observe the same thing.

My test capture gets conversion artefacts at about 4kHz and -72dB

@Tim : I can provide the WAV file if you like. I used CoolEditPro's Frequency 
Analysis


> -----Message d'origine-----
> De : wdmaudiodev-bounce@xxxxxxxxxxxxx 
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] De la part de Jeff Pages
> Envoyé : vendredi 23 juillet 2010 06:35
> À : wdmaudiodev@xxxxxxxxxxxxx
> Objet : [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> Hi Frank,
> 
> I first raised it here on the 14th May 2007, and Hakon 
> Strande replied:
> 
> >Vista RTM shipped with a float-int conversion bug where we 
> truncate instead
> of rounding.
> >This could be the cause of what you are seeing. Please tests 
> with SP1 beta
> when it ships
> >(no, I don't know when that is) to see if this has been 
> addressed with
> those bits. If not, please report back.
> 
> After SP1 was released, I tested it and found the problem was still
> occurring, so I sent another query on the 7th December 2007. 
> Hakon replied,
> asking for more information, but for some reason his reply 
> ended up in my
> spam folder and I didn't see it until I was clearing it out 
> some six months
> later. I e-mailed him off-list then (29th May 2008) but 
> didn't hear back.
> 
> In August 2008 Andrew Elder asked about Vista's SRC quality 
> and on the 5th
> September I replied with a link to some screen shots showing 
> the artefacts I
> was observing (the link is
> http://www.innescorp.com.au/uploads/downloads/other/vistacaptu
> resrc.pdf),
> but the discussion fizzled out soon after that.
> 
> So far it hasn't been anything more than a curiosity for us, 
> as none of our
> customers have complained yet, but I keep raising it whenever 
> the subject of
> SRCs comes up in the hope that maybe eventually there'll be a 
> solution.
> 
> Jeff
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Frank Yerrace
> Sent: Friday, 23 July 2010 2:08 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> Yes you are correct about WASAPI's IAudioClient::Initialize.
> 
> Jeff- just curious- when you reported the problems, how did 
> you go about
> reporting them, and approximately when?
> 
>  
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jeff Pages
> Sent: Thursday, July 22, 2010 7:18 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> Doesn't the IAudioClient::Initialize function in WASAPI 
> require in shared
> mode that the sampling rate be the same as what the audio 
> engine is set to,
> or in exclusive mode be a rate that the hardware supports, so that the
> Windows SRC is never invoked?
> 
> In any case, WASAPI isn't supported on XP, so the 
> applications our customers
> are using are unlikely to be using that API for a long time 
> to come. What do
> we tell them when they start complaining about capture 
> artefacts on Windows
> 7?
> 
> Jeff
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Larry Osterman
> Sent: Friday, 23 July 2010 12:06 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> Sure - use WASAPI for capture - that will use the same 
> resampler as is used
> for output. 
> 
> DSound uses the same resampler, but when capturing mono 
> inputs, because
> DSound is primarily a game API, it tunes the resampler for 
> performance, not
> fidelity (I don't know if there are knobs to make the DSound resampler
> operate at a higher fidelity).
> 
> Larry
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jeff Pages
> Sent: Thursday, July 22, 2010 6:47 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> The applications I've used include Cooledit and Adobe 
> Audition, as well as a
> spectrum analyser program I wrote which used the wave API. On 
> XP I believe
> capture always used the "best" converter regardless of API, 
> and I don't see
> the problem on that platform (all the converter artefacts are 
> below -96dB).
> Is there any way in Vista or Windows 7 to force it to use a 
> better quality
> converter on capture?
> 
> Jeff
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Larry Osterman
> Sent: Friday, 23 July 2010 11:29 AM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> What API are you using to capture?  It's possible that you're 
> using one of
> the lower quality resamplers in the box (for instance if 
> you're using the
> wave APIs, I believe you'll use the ACM resampler which is 
> basically the
> same resampler used in XP).
> 
> Larry
> 
> 
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jeff Pages
> Sent: Thursday, July 22, 2010 4:20 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> 
> Tim wrote:
> >The purists might disagree, but it has been my experience that the 
> >Windows sample rate converter is pretty good for most purposes.  How 
> >are you detecting the noise at 4 kHz?  Are you injecting a 
> pure signal 
> >and doing a spectrum analysis on the result?
> 
> While the render sampling rate converter in Windows 7 is very 
> good, the
> capture converter is a different matter entirely. It has conversion
> artefacts at about -65dB on a pure tone. I first noticed this 
> back when
> Vista was released and tried reporting it a couple of times 
> but got nowhere,
> and the problem has persisted into Windows 7.
> 
> Jeff
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