[PD] band limited (anti-alias) techniques

David Medine dmedine at ucsd.edu
Tue Nov 24 18:21:25 CET 2015


Välimäki and Houvilainen have published  a number of articles about 
something called 'differentiated parabolic waveforms'. Basically, you 
square a digital sawtooth and put it through a one-zero differentiating 
filter (y(n) = x(n) - x(n-1)). What you get out is a slightly rounder 
(less aliasing) sawtooth. I've never actually tried this, but it looks 
pretty interesting and could easily be patched. Super simple.

The CMJ paper explains it in full detail. You might need a 
University-style subscription to get the actual PDF:
http://www.mitpressjournals.org/doi/pdf/10.1162/comj.2006.30.2.19
but the reference is:
Välimäki, Vesa, and Antti Huovilainen. "Oscillator and filter algorithms 
for virtual analog synthesis." /Computer Music Journal/ 30.2 (2006): 19-31.


On 11/23/2015 6:07 PM, Christof Ressi wrote:
> I can think of at least two:
>
> 1) wavetables filled with sinesum/cosinesum (possibly blending between different wavetables according to frequency --> many partials for low pitches, few partials for high pitches)
> 2) transition tables (check out 3.audio.examples/J09.bandlimited)
>   
>   
>
> Gesendet: Dienstag, 24. November 2015 um 02:30 Uhr
> Von: "Alexandre Torres Porres" <porres at gmail.com>
> An: "pd-list at lists.iem.at" <pd-list at lists.iem.at>
> Betreff: [PD] band limited (anti-alias) techniques
>
> hi, I know about the oversampling + filtering technique, which you can patch it, but what are other techniques for creating band limited signals you people know (not only those you could do it as a pd patch)? Yes, I'm thinking about oscillators mostly.
>   
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