[pd] FFT sine to saw oscilator (was:[pd] hanning window + fft)

[Mathieu Bouchard]

On Mon, 4 Sep 2006, mami music wrote:

> Hey guys thanks for the explanation!. goin further in the study of fft 
> and applications, iam designing an oscilator that is capable to go from 
> pure sine tone (fundamental harmonic) to a saw (all harmonics)...

Try a spectrum made like s(k) = k^(-1/p). When p=1 it'll give f^-1, the 
spectrum of (one kind of) saw wave at base frequency. When p goes towards 
0, it goes through k^-2, k^-3, etc. with gradually less powerful 
harmonics. with p=0, it gives a division by zero, but the limit of s(k) 
when p->0 is s(0)=1 and s(rest)=0, which is a sinewave.

to produce a spectrum for a frequency multiple of the base frequency, just 
space out the s(k) using zeros. for a frequency not multiple of the base 
frequency, a lot of extra processing is necessary.

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| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada