[Bug 14717] resampled sound is horrible

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=14717

--- Comment #22 from Alexander E. Patrakov <patrakov at gmail.com> 2010-11-26 10:36:41 CST ---
I have built Wine with the second version of your patch. The sound is not
horrible (in fact, I cannot distinguish it from the one from the best
resampler), but, according to both your plot and the following unscientific
test, your resampler is definitely not the best.

Now the test:

1) Install foobar2000 in wine and JAAA in linux

2) Configure Wine to output sound through JACK at either 96 or 192 kHz sampling
rate, as permitted by your hardware

3) Run foobar2000, play a CD rip. Route its audio output to "jaaa -j" using
something like qjackctl or patchage

4) Inspect the spectrum of wine output in realtime using JAAA. Use the "peak
hold" option. You will see that, on typical contemporary music, the ultrasound
components after your resampler peak at something like -80 dB. This also agrees
with your plot.

Yes, I know that I should really look at distortions below 20 kHz, not at
ultrasound components, but there are no such easy-to-use tools for it.

5) Now enable the resampler plugin in foobar2000's DSP manager (so that your
resampler is out of the way now) and look at the spectrum again. The ultrasound
components are at -120 dB now.

Moreover, without the "peak hold" option, it is obvious that foobar's
ultrasound is noise + occasional glitches, while your resampler's ultrasound is
visibly correlated with the sound that is piped through it.

The default ALSA resamplers can also be compared with your resampler this way.
Use an .asoundrc that routes the audio output from ffplay through a plug plugin
and then to jack. All of the working ones (pph aka speex, and libsamplerate)
keep the ultrasound noise at -120 dB.

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