[PD] Anti-aliasing filter

[julien.breval at tremplin-utc.net]

Selon Martin Peach <martinrp at vax2.concordia.ca>:

> julien.breval at tremplin-utc.net wrote:
> 
> > Another solution is to calculate the highest partial that won't produce 
> > aliasing, in function of the fundamental.
> > If we call F the fundamental, the k-th partial will have a frequency of F +
> k*F 
> > (if you chose another harmonicity system, you may adapt this formula). 
> > Therefore the maximum number of computable partials of the F fundamental is
> the 
> > integer part of (22050-F)/F. 
> > For F = 10 Hz, you can compute 2204 partials
> > For F = 1000 Hz, you can only compute 21 partials 
> > The idea, here, is to limit the number of partials to the maximum (you can
> 
> > evaluate this maximum in realtime, in function of the fundamental). You can
> 
> > either mute the partials that outpass the limit (the most simple solution)
> or 
> > not even calculate them.
> 
> The effect of ultrasonic partials can be very audible. The sound seems 
> to come from intermodulation distortion in the ear sensors themselves, 
> which is causing lower frequency artefacts. Any calculation to simulate 
> this effect (e.g. multiply together the ultrasonic partials while adding 
> the audible ones) would perhaps add realism to the sound of higher 
> frequency complex tones.

of course

(but I'm not looking forward to use additive synthesis for emulating other 
sounds)