[wdmaudiodev] Re: Capture with USBAudio under Windows 7 noisy
- From: Larry Osterman <Larry.Osterman@xxxxxxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Fri, 23 Jul 2010 02:05:38 +0000
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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