Reduce audio resampling noise

[cbernier]

Downsampling is better that upsampling, but still it causes a lot of noise. The main reason seem to be because the buffers that get processed (resampled) are very small (~2048 bytes) so the approximations is bad for about 0.1% of the samples. Increasing the decoder output buffer size helps a lot but unfortunately it was not that simple : cbernier@86986f9
Is there a simpler way?