[wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
- From: Hakon Strande <hakons@xxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 4 Aug 2010 20:03:37 -0700
Jeff,
Sorry that your second query went unanswered back then in 2008. I am not sure
why - I may have had email issues same as you. :-) I do try hard not to drop
issues on the floor.
These days I am not working on audio but you are in good hands with Frank.
My apologies again,
Hakon Strande, PM - MS Hardware
> From: jeff@xxxxxxxxxxxxxxxx
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
> Date: Fri, 23 Jul 2010 14:34:55 +1000
>
> 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/vistacapturesrc.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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