Path: utzoo!attcan!uunet!samsung!sdd.hp.com!hplabs!hpl-opus!hpnmdla!hpsad!smithj
From: smithj@hpsad.HP.COM (Jim Smith)
Newsgroups: comp.music
Subject: Re: Time change without pitch change
Message-ID: <2650002@hpsad.HP.COM>
Date: 11 Jul 90 00:10:14 GMT
References: <31559@cup.portal.com>
Organization: HP Signal Analysis Division - Rohnert Park, CA
Lines: 23

The cleanest digital algorithm to do what you want is called a Phase Vocoder,
but it is really computationally intensive, as you mentioned.  Here
are a couple of good references:

The Use of the Phase Vocoder in Computer Music Applications
James A. Moorer 
Journal of the Audio Engineering Society
Jan/Feb 1978, V26 N1/2, pp42-45

Implementation of the Digital Phase Vocoder using
the Fast Fourier Transform
Michael R. Portnoff
IEEE Transactions on Acoustics, Speech, and Signal Processing
Vol. ASSP-24, No 3, June 1976

And probably the best first article on the topic;

The Phase Vocoder: A Tutorial
Mark Dolson
Computer Music Journal, Vol.10, No.4, Winter 1986 pp14-27

Mark was with the computer music department at UCSD,
and perhaps they would have reprints.