[pulseaudio-discuss] Resampler quality evaluation: now with room noise!

[David Henningsson]

On 2014-09-25 21:54, Alexander E. Patrakov wrote:
> The conclusion of that work was that we need to use speex-float-5 to
> match the metric of "never introducing audible distortions" (that other
> operating systems meet by default) when resampling from 44.1 to 48 kHz.
> However, David Henningsson argued that this "never" included a lot of
> unrealistic worst-case conditions, i.e. that the quality achieved in
> proprietary OSes is actually overkill.

To elaborate, I'm not saying they're completely unrealistic, I'm don't 
doubt that the resampler noises are hearable in *some* environments. The 
question is how common it is.

We need to find a balance between quality on one side and CPU 
consumption on the other side.

We used to have speex-float-3 but changed to speex-float-1 because 
distros had changed, which in turn was because people complained that PA 
took too much CPU. So speex-float-3 was causing problems for some people.

So, as a very rough measure, if we have one set of people complaining 
about resampler CPU consumption, and another set of people complaining 
about resampler noises, and the size of those two groups are roughly 
equivalent, we're somewhat on a balance. :-)

I think your findings are very interesting when comparing different 
resamplers though - i e, that speex seems to give best quality, given a 
fixed processing power.

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic