On Sun, 2014-09-07 at 16:32 +0600, Alexander E. Patrakov wrote: > [sent only to Tanu by mistake, resending to the list] > > 07.09.2014 15:48, Tanu Kaskinen wrote: > > On Sun, 2014-08-24 at 13:35 +0600, Alexander E. Patrakov wrote: > >> 04.08.2014 19:29, I wrote: > >>> Anyway, I think that the task of objectively testing the resampler > >>> speed and quality also needs to be done, in order to provide such > >>> justifications. Please see > >>> http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-February/019968.html > >>> for the formulation. > >> > >> Now I have the tools for the basic form of quality evaluation (using a > >> linear sine sweep). The tools can compare quality of various resamplers, > >> including those found in proprietary operating systems. However, the end > >> result is still not good enough to answer the question "is this > >> resampler good enough". The (useless) answer is almost always the same: > >> "no, here is a sine wave frequency that it either attenuates audibly or > >> distorts audibly", even though nobody listens to e.g 18 kHz sine waves. > >> > >> I will test the two new resamplers among the others today. > > > > Do we have some kind of a conclusion about whether the soxr and > > libavresample resamplers should be merged? If I understood correctly, > > the libavresample resampler appears to be somehow broken, so I guess > > that should not be merged until the brokenness is fixed. > > Correct. > > > Did the soxr > > resampler end up being the best one in any of the following categories? > > > > 1) Best quality > > The problem with this question is that there are perfect resamplers in > terms of perceived quality. It has no meaning to compare e.g. > speex-float-5 and speex-float-10 in terms of quality. Both are just > perfect when given a task of resampling from 44.1 to 48 kHz. > > At MQ or HQ quality, soxr is perfect, too. > > > 2) Fastest > > Definitely not, at least at quality levels above QQ. And at QQ, I have > not tested, and at that level it is just a cubic interpolator. I think > we don't need a complex library just for cubic interpolation. > > > 3) Fastest without any audible distortions > > Definitely not, by a factor of 10 (over speex). > > > 4) Best compromise between speed and quality > > Definitely not. > > > X) Some of the above when applying licensing constraints > > Definitely not. The winner on all points is speex. At the quality level > of 5, it never creates audible distortions. And at any quality higher > than 2, it eats less CPU than any comparable (in terms of quality) > competitors. Thank you! I'll remove this patch set from the wiki then. > At this point, I also suggest removing libsamplerate-based resampler. Sounds reasonable to me. -- Tanu
