[PD] band limited (anti-alias) techniques

Charles Z Henry czhenry at gmail.com
Tue Nov 24 18:14:31 CET 2015

I have an external for an anti-aliasing table reader (tabread4a~),
which is almost certainly more efficient than upsampling+filtering,
works on any table, and doesn't require analysis/synthesis.  It's
computing cost scales linearly with increases in playback speed faster
than simple playback.  It scales all the way up to Nyquist where the
signal just quietly vanishes (although at substantial cpu load. For a
256 point table, it's equivalent to the cost of running 128 tabread4~
readers when scaled up to the Nyquist freq).

It needs some updating, was never written optimally, and I never was
satisfied with the method of numerical differentiation used to compute
playback speed from the index array.

Anyway... the point of which is generality (yay math)--the method is
not comparably great for oscillators that you already know in advance.

On Tue, Nov 24, 2015 at 10:46 AM, Alexandre Torres Porres
<porres at gmail.com> wrote:
> I didn't think about other solutions in a patch besides oversampling +
> filtering and I considered it too expensive and not perfect. I assumed most
> of the techniques for bandlimiting wouldn't be possible as patches and/or
> would be inefficient.
> But you (all) tell me :)

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