[sdiy] Generating acyclic waveforms?

[Scott Nordlund]

> Simon Brouwer wrote:
>> I see two other ways:
>> - using wavetables (very long ones)
> I'd discounted wavetables just because they would have to be very long,
> but memory is cheap, so why not.
>
> What about Wave Terrain synthesis? Is there an sdiy implementation
> anywhere? Load up a 2-d matrix with a surface of choice and then read
> linear subsections. Altering the start and end coordinates over time to
> vary the output waveform.
>
> -Dave

I've tried wave terrain synthesis in Pure Data.  It's neat to think about,
but the results I've gotten aren't drastically different from FM or 
waveshaping or similar things (you could kind of consider waveshaping and 
FM to be subsets of wave terrain).  My implementation scanned a surface 
(defined by an arbitrary equation, F(x,y)) with a sort of lissajous figure
that could be scaled, rotated, offset, etc.  To get something decent 
sounding, I limited the surface and modulation to continuous, bounded 
functions (lots of sin, cos, atan).  A surface with discontinuities or 
singularities isn't going to sound so great.

Anyway, yes, there's plenty of room for inharmonics and animated and 
complex sounding things, and it's nice that any of the inputs can be used
with envelopes or slow or fast modulation or whatever, but there's also 
a lot of unintuitive messing about to avoid sudden and "unmusical" timbral
changes, or just to generally come up with something interesting.

The end result resembles something that might be more easily obtained from
FM/waveshaping with arbitrary waveforms.  In fact that might be a better
approach, because it's difficult to make an equation for an interesting
surface.

I'm not saying it's not interesting or potentially rewarding, but it's not
the revelation that I'd hoped for.  Imagine FM with several added layers
of confusion and obfuscation and you won't be too far off.
 		 	   		  
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