STRETCH: Time stretching using frame
interpolation. To shrink a sound, use
SHRINK.

For pvoc stretch but using D = I, and interpolating
in the frequency domain. 

The program seems to perform best
when D=I=N, M/N = 8. When D,I < N, the result gets noisier.

thus:
punk> fromsf -H scholar|  stretch -S2 -N2048 -D2048 -I2048 -M16384 | tosf -R44100 tool

not only sounds much better than

punk> fromsf -H scholar| stretch -S2 -N2048 -D512 -I512 -M16384 | tosf -R44100 confetti

but also runs much faster. 

I have gotten good results with stretch factors of
20, without the usual harmonic warbling effect.

This program is mainly of interest due to
working much quicker than the traditional
phase vocoder time stretch where I is set to
some value larger than D. The quality of
resynthesis seems comparable to traditional
time stretching. 

UGLY SECRETS:

Oscillator bank resynthesis is disabled, as is
resynthesis from analysis data. If enough people
complain I might try to change this.
