pitch shifting algorithm

[flatmax <flatmax@xxxxxxxxxxxxxxx>]

Hello,

I am involved with a group of musicians called 'Elefant Traks' who are
based in Sydney Australia.
One member of the Elefant Traks team have produced what was the first web
jamming software called 'Dase' it can be freely downloaded from :
http://www.singularity.net.au/dase/dase.htm

This software requires a good pitch shifting algorithm ... time/frequency
scale modification ....
Can anyone out there suggest algorithm references ?

I was originally thinking of resampling the frequency spectrum based on
frequency warping ... i.e. transforming the fft of the signal into the
perceptual 'pitch' domain and resampling ... then reverse transforming,
but I believe this may induce group phase errors ... any thoughts ?

thanks
Matt