[pulseaudio-discuss] [PATCH 0/4] Add support for libsoxr resampler

[Andrey Semashev]

On Wednesday 12 November 2014 20:03:48 Alexander E. Patrakov wrote:
> 12.11.2014 14:26, Alexander E. Patrakov пишет:
> > I will recheck the quality separately later today, in order to verify
> > that it is still as good as in the previous tests. Please don't merge
> > the patches until this is done.
> 
> Done. The -mq, -hq and -vhq variants of the resampler never produce
> audible distortions. The -lq variant sometimes does, by means of
> suppressing very high frequencies, but this is relevant to artificial
> tests only, and only if the listener knows that these frequencies are
> supposed to be there. Thus, quality is on par with speex-float-5, the
> CPU consumption is even better than with speex-float-1. Conclusion:
> 
> *** the patches are generally acceptable ***

Great! And thanks a lot for the quality data and information. I will send v2 
patches in a day or two.

> However, because the low-quality and high-quality versions eat very
> similar amount of CPU time, I'd just expose a single (high or very high)
> quality setting.

Given that -lq is actually slower than -mq in some cases and has worse 
quality, I agree there is no point in keeping it.

However, the other three presets do have different performance and quality. In 
my test results [1] -mq is about 2 times faster than -vhq, and -hq is 
somewhere in between. Performance wise, there should be no problem with -vhq 
on modern CPUs, but maybe the little extra would be desired in embedded domain 
to conserve battery. Do you think we could keep the three presets: -mq, -hq 
and -vhq?

[1]: http://lastique.github.io/src_test/