tree 45300badf92767cdacc05caf0f8adc541f413d64
parent c35e060b0ea65d6a77efca0b72f96f45e841291a
author Ryan C. Gordon <icculus@icculus.org> 1505976674 -0400
committer Ryan C. Gordon <icculus@icculus.org> 1505976674 -0400

audio: Replaced the resampler. Again.

This time it's using real math from a real whitepaper instead of my previous
amateur, fast-but-low-quality attempt. The new resampler does "bandlimited
interpolation," as described here: https://ccrma.stanford.edu/~jos/resample/

The output appears to sound cleaner, especially at high frequencies, and of
course works with non-power-of-two rate conversions.

There are some obvious optimizations to be done to this still, and there is
other fallout: this doesn't resample a buffer in-place, the 2-channels-Sint16
fast path is gone because this resampler does a _lot_ of floating point math.
There is a nasty hack to make it work with SDL_AudioCVT.

It's possible these issues are solvable, but they aren't solved as of yet.
Still, I hope this effort is slouching in the right direction.

--HG--
extra : rebase_source : 2178d7f422d118dfb76608964f63d290b18c7408
extra : histedit_source : 5461b7f3025ed6c09213910a563318c95d185bf3%2C4a6a6c4c38784b4bc5f241d963c0d752c73ea5b9