[music-dsp] Wavetable/anti aliasing-2
James W. Morris
sirrom75 at hotmail.com
Thu Mar 25 16:38:58 EST 2004
I'd like to be able to understand what you've been discussing in the Re:
[music-dsp] Wavetable synthesis/anti aliasing thread, but I'm not that
However, I've written a user definable wave form where the user inserts
'vertex's (as many as required) which consist of a horizontal part - degree,
and, a vertical part - level. The levels are just ramped from one vertex to
the next to create the shape.
It gives a similiar problem to that being discussed (i think): more complex
shapes and/or high frequencies cause some vertices to drop out (if
deg_difference_as_samples < 1, skip to next) which causes a kind of burping
noise. (although I'm the type of person who'd try and take advantage of it)
Just to give you some idea of my level of dsp knowledge: the lowpass filter
I've written calculates the average level of n samples stored in an array,
where n is directly proportional to the cutoff frequency. - ie limited to
fairly basic maths and algorithms.
What i'm considering for my problem is calculating the highest frequency the
waveform can operate at (using a minimum noof samples between 2 vertices as
a guide), and then automatically creating substitute wave forms for the
higher frequencies... but the construction of these I'm not quite sure about
- choosing which vertices can be thrown out without too much loss of
I probably won't be trying to tackle it for a while though, like >six
months, giving programming a break, very soon, just after....
Just thought I'd mention it.
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