There are many ways to achieve audio time stretching without transposition . Some time-based methods build on Pierre Schaefer 's Phonogène . Another approach consists in processing the sound in spectral domain, using a phase vocoder . In this case, the audio samples are converted to spectral data through a Fast Fourier Transform (FFT). Then, even if we focus on extreme time stretching, the details of the phase vocoder implementation have important consequences on the sound quality and the tool's flexibility for live usage. Before introducing the Max for Live device Spectral Stretch, let's have a look at a selection of four possible algorithms: Paulstretch Max Live Phase Vocoder Interpolation between recorded spectra Stochastic Re-synthesis from a recorded sonogram Paulstretch Paul's Extreme Sound Stretch , also known as Paulstretch , is an algorithm designed by Paul Nasca for extreme time stretching. You might have heard one application already: to this date,
Groundswell is a wonderful organization dedicated to the development of new music in Winnipeg and the Province of Manitoba, Canada. I've been invited to serve as a member of the committee for their first electroacoustic music competition, along with composer Margaret Schedel and composer William Brunson . It's been a fun and quite interesting adventure. We listened to more than two dozen compositions. I wish we could have included more than 5 finalists: there were a number of atypical nice compositions. To listen, head to the competition page . You'll find links to the finalists' music.
When I discovered electronic music during the Centre Acanthes 2000/Ircam , my favorite topic was real time sound processing in frequency domain. Hans Tutschku taught the wonders of AudioSculpt in Avignon, before Benjamin Thigpen taught Max/MSP in Helsinki. Now, the Computer Music Journal just published an article I wrote about spectral sound processing in real time and performance time ( whereas real-time treatments are applied on a live sound stream, performance-time treatments are transformations of sound files that are generated during a performance ). If you are interested in graphical sound synthesis, phase vocoder , and sonograms (or spectrograms) , I hope you will enjoy this tutorial. The great news is that you can download the article for free on the page of the Computer Music Journal, Issue 32, Volume 3 . Max/MSP/Jitter patches You can readily apply the described techniques in the development environment Max/MSP/Jitter . For a hands-on approach, make sure you download t