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Shifting tempo but not pitch…

May 17, 2010 | 4:01 am

I’m looking to be able to shift the speed of a sample without changing the pitch of the playback. I’m wondering if anyone has done anything like this in Max or if anybody has any idea’s about how to approach the problem.


May 17, 2010 | 6:07 am

I think I may have just answered my own question. I found some great stuff on spectral analysis by Jean-Francois Charles here:

http://www.cycling74.com/share.html


May 17, 2010 | 6:09 am

You could shift the pitch with gizmo~ by a factor that’s the inverse of the speed factor.


May 17, 2010 | 6:46 am

I would use gizmo~ too, since it generally gives you decent results and is very simple to use. The more traditional way of approaching this (without FFT) would be to split the sound in small grains with a windowing function, then discard some of the grains (e.g. discard half of them if you want twice the tempo) and join them together again. (While experimenting a bit with different overlaps and window functions to get a smooth result.)

In the opposite case of making the sound play back -slower-, you’d simply repeat certain grains instead of discarding them.


May 17, 2010 | 7:41 am

I just tried the gizmo~ setup and it works pretty well for standard tempo shifting. However I’m trying to slow WAAAAAAAY down. Somewhere in the neighborhood of 0.001 of the original speed. Essentially where a momentary snare drum hit would turn into a soundscape.

Jean-francois’s "3-record-play-speed-control" that I found on the above link is more the type of thing I was thinking about. Although, clearly I’m going to be spending some time in the Jitter tutorials to understand what he has going on!


May 17, 2010 | 8:14 am

Hello, you should also try this :

http://cycling74.com/2006/11/02/the-phase-vocoder-%E2%80%93-part-i/

http://cycling74.com/2007/07/02/the-phase-vocoder-part-ii/

It is perfect for what you want to do !

Have a nice day

Mathieu


May 17, 2010 | 9:04 am

A simpler route would be granulation; there’s a very clean granulator from GMEM, called GMU (google); i’ve also built my own here:

poly sub:

– Pasted Max Patch, click to expand. –

main:

– Pasted Max Patch, click to expand. –

Brendan


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