The following variants are implemented:
lipshitz noise shaping dither
shibata noise shaping dither
low shibata noise shaping dither
high shibata noise shaping dither
f-weighted noise shaping dither
modified-e-weighted noise shaping dither
improved-e-weighted noise shaping dither

Data tables taken from SOX
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>