Harmonix content formula

[mbartkow at ET.PUT.Poznan.PL]

Paul, 

again sorry for replying so late:

> >FT fade is exactly the same as time domain fade, because FT is a linear
> >transformation. You gain nothing interesting this way.
> >
> >m.b.
> 
> Is it?
> 
> If you do a cross fade between a saw and reverse saw, in the middle you get 
> no waveshape at all...

what do you mean by no waveshape ?

> with fourier analysys/transform  in the middle you would get a triangle.

Unfortunatelly, you are wrong. Just do the math or believe what
the books say. Linearity is a fundamental property of the Fourier 
Transform.

Unless by saying "in the middle" you mean something different than A(f)/2+B(f)/2 
(where A(f) and B(f) are the Fourier spectra of the a(t) and b(t) signal),
what you achieve is the spectrum of a(t)/2+b(t)/2 which is a simple and 
boring half-way crossfade. 

Anyway, I recommend you an interesting paper on morphing of audio signals:

http://web.interval.com/frameset.cgi?papers/1995-061/index.html

regards,

mb


--

Maciej Bartkowiak, PhD
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