[linux-audio-dev] Re: Looking for fast integer resampling code

[Kjetil Svalastog Matheussen]

Dave Chapman:
>
> The most common case will be downsampling 48KHz->44.1KHz, but there are
> also users who need upsampling from various lower frequencies (e.g. for
> use with audio books).
>
> So we're looking for pointers to any high quality (but fast!) resampling
> code that could be used.

I recently did a lot of benchmarking between libsamplerate and mus_src
in clm/sndlib. My result was quite interesting, the fastest mus_src sinc
resampler where a lot faster than the fastest libsamplerate resampler.
I don't have the results available right now, but I remember that mus_src
performance wasn't very far from beating the linear resampler in 
libsamplerate.

I did a lot of test with various types of data and compiler-options, so I 
don't think it was a coinsidence. However, it might have been because 
of some optimalization gcc was doing or something to do with the 
cache. The mus_src code is far smaller and easier to read than the one 
for libsamplerate.

I did not hear any difference in soundquality, but I guess there might be
a difference.

Sndlib:
http://ccrma.stanford.edu/software/snd/snd/sndlib.html
mus_src is available in the file clm.c .

libsamplerate:
http://www.mega-nerd.com/SRC/

A third program is the original sinc-resampler from Julius Smith:
http://ccrma-www.stanford.edu/~jos/resample/
I don't know how this one performs compaired to the other two though.


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