[sdiy] Polybleps and arbitrary waveforms

Olivier Gillet ol.gillet at gmail.com
Wed Mar 30 12:12:36 CEST 2016

Polybleps are used to band-limit a *discontinuity* in the waveform (or
its derivative, eg for triangle/slope synthesis).

Do we really want to model discontinuities in wavetable data? When
your 256-sample wavetable contains the following data: "... 150, 148,
146..." does it really mean that we should play a sample value of 150,
hold it for f0 / 256, and then play a sample value of 148?

If this is your goal, yes, polybleps are useful. What you describe
would actually synthesize a band-limited version of the signal you
would obtain by using a variable clock rate and a ZOH. Useful for a
Prophet-VS emulation...

For (almost) band-limited wavetable playback I'd recommend this instead:

On Wed, Mar 30, 2016 at 11:38 AM, Gordonjcp <gordonjcp at gjcp.net> wrote:
> I was thinking about polybleps and it occurred to me - if you could compute the polyblep fast enough, could you do that for every sample read from a wavetable and thus antialias any wave you play back?
> --
> Gordonjcp MM0YEQ
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