[sdiy] Wave terrain synthesis (was Re: Generating acyclic waveforms?)

[Scott Nordlund]

> I find it very interesting that this technique makes similar sounds
> to FM, since in my mind it is more closely related to wavetable
> synthesis than either of the nonlinear techniques you mention
> (waveshaping and FM). I can completely imagine that it is difficult
> to control or predict what you'll get out. Experimentation is good,
> but sometimes you're aiming for something particular and it would be
> nice to be able to get closer.
>
> Thanks very much for a practical report on this.
>
> T.

Well the fact that it sounds like FM is at least partly due to the 
way I define the "wave terrain" surface: a function rather than a 
ROM lookup or something.  I thought it would be easier and I wouldn't
have to worry about interpolation or anything, and also it doesn't 
suggest any particular "correct" way to traverse the surface.

I suppose another approach would be to use an interpolating scanner
to crossfade between a number of waveforms, either samples or 
created via additive synthesis (I don't really know of a better way
to make a wavetable in two dimensions).  This could then be scanned
with arbitrary continuous functions, which I think would make it 
sound kind of samey, or at least unpredictably different from the 
original waves.  Or it can be scanned "horizontally" with a fixed
amplitude sawtooth wave, provided all waveforms are well behaved
at their endpoints (assuming you want to avoid discontinuities).
 But this is just a PPG style wavetable with arbitrary "vertical"
modulation.

I haven't messed with it in a while.  I think it's worth further 
effort, even if the novelty of it is ultimately more impressive
than the sound.

 		 	   		  
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