Windows 7's resampling sucks, How can it be improved? Options

[googlebot]

Playback over WASAPI must match the sample rate of the output device. Thus applications must supply their own resampling if the playback rate does not match. Most applications don't do this but just employ MME or DirectSound, which provide transparent resampling for non-matching rates.

Since some of my content is 44.1 kHz and some 48 kHz I used to set the output rate to 192 kHz so that all audio had to be upsampled. With good software resampling and a cheap onboard codec this could, in theory, even improve the overall result. But the opposite was true. Today I couldn't longer ignore the impression that the resampled output sounded somewhat muffled and did some measurements.

You can view the result here. The upsampled output (44.1 -> 192 kHz) suffers from quite a HF roll-off in comparison to pure 44.1 kHz output.

In Windows XP the SRC quality could be adjusted. I can't find anything comparable in Windows 7. Does anyone know more?

This post has been edited by googlebot: Feb 9 2011, 20:33

[[JAZ]]

Couple of things...

It looks like foobar2000 implementation of WASAPI uses the exclusive mode. (it doesn't allow other apps to make sound when playing)
I've managed to implement the shared mode, and indeed I wasn't right. The documentation doesn't explicitely say that you cannot use another setting than the one returned to you by the call to GetMixFormat() (Ok, it says it in the page you pointed, but that's not explained in the interface definitions). On the other hand, at least the bitdepth is 32bit float.

In this case, you are right that an application using the shared mode would need to have a resampler if it wants to use multiple samplerates.


I also took the time to install rmaa6 and test this laptop's integrated soundcard with a loopback cable. The results I got are like yours, but I still think you exaggerated.
Having 16bit 44Khz in rmaa, 16bit 192Khz in speakers, and 16bit 44Khz in line in gives me the same graphic that you got (the one with smooth rolloff). If I use 16bit 44Khz -> 16bit 96Khz -> 16bit 44Khz, then the rolloff is still stronger, yet not by much more.

Having all three set to 16bit 44Khz in all doesn't give me as good a graphic than you, it is just partially better, and using 16bit 96Khz in all gives me a very nice response.
comparisons
96Khz

This post has been edited by [JAZ]: Feb 11 2011, 01:11