[PD] a little pitchshifter

padawan12 padawan12 at obiwannabe.co.uk
Tue Mar 6 18:55:31 CET 2007


Helpfile B.14.sampler.rockafella may be a good place to start.

On Mon, 5 Mar 2007 14:15:26 -0600
"Mike McGonagle" <mjmogo at gmail.com> wrote:

> I don't want to change the subject (and if needed, we can start a new
> thread), but as this might be a related topic, here it is...
> 
> What would it take to turn this into a "Slowdown" abstraction?
> Basically, I am interested in slowing down the tempo of a sound, but
> NOT changing the pitch...
> 
> Am I off-base on this? Or can this be used as the starting point for
> what I described?
> 
> Thanks,
> 
> Mike
> 
> 
> On 3/5/07, Frank Barknecht <fbar at footils.org> wrote:
> > Hallo,
> > Kyle Klipowicz hat gesagt: // Kyle Klipowicz wrote:
> >
> > > Could aliasing be avoided by using a multi-pole low pass filter at
> > > nyquist before sending the signal to the dac?
> >
> > No: Alias frequencies aren't too high, they are wrong frequencies,
> > that have been mirrored at the Nyquist border. As soon as you try to
> > play a sinewave at Nyquist + x, what you get is a sine at Nyquist - x,
> > and you cannot lowpass out this frequency after it has been
> > introduced.
> >
> > You can however upsample your signal first, then use a lowpass filter,
> > then downsample again. See this chapter in The Book for more info:
> > http://crca.ucsd.edu/~msp/techniques/latest/book-html/node194.html
> > and J07.oversampling.pd
> >
> > Ciao
> > --
> >  Frank Barknecht                 _ ______footils.org_ __goto10.org__
> >
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> 
> 
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