[music-dsp] changing tempo without changing pitch

Joshua Scholar joshscholar at yahoo.com
Tue Jan 6 02:52:00 EST 2004

For an example of relatively high quality tempo changing you can look up
Olli Parianinen's PaceMaker.

It uses a time domain technique and sounds much better than other techniques
for changes of say 25% or less.

As the examples on that timepitch page show, only the proprietary technique
sounds acceptable for stretching by 100% or compressing by much.

The phase technique gargle and echo and FFT based techniques (that I've
heard) destroy all transients, turning them into spread out noise.

I played with trying to tempo change in what was essencially an MPEG level
III domain and the results sounded just like the phasing technique (perhaps
a bit worse).  Even putting in a layer that tried to detect and fix up the
temporal envelopes (multiresolution) to compensate for phasing problems
improved the results significantly but no where near enough.

That timepitch page points at a PHD thesis on a method that probably works
pretty well, but it would be a huge task to implement.

----- Original Message -----
From: "Holger Strauss" <holger.strauss at vcs.de>
To: <music-dsp at shoko.calarts.edu>
Sent: Monday, January 05, 2004 11:29 PM
Subject: AW: [music-dsp] changing tempo without changing pitch

> Try http://www.dspdimension.com/html/timepitch.html and follow the
> references.
> Holger
> > Anyone have pointers to articles or code that related to this?
> dupswapdrop -- the music-dsp mailing list and website:
> subscription info, FAQ, source code archive, list archive, book reviews,
dsp links
> http://shoko.calarts.edu/musicdsp
> http://ceait.calarts.edu/mailman/listinfo/music-dsp

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