[sdiy] Approximating sine with plain integer math

Richie Burnett rburnett at richieburnett.co.uk
Thu Apr 7 21:38:58 CEST 2016


> I'm just not sure I understand what "ugly"
> is here - are we talking aliasing noise...

Yes.  Frequency components that shouldn't be there and sound discordant.

> Either way, it's something I have to
> think you'd address outside of the oscillator proper, with some kind
> of filtering, which is also going to be involved in the softsynth
> total...

It has to be addressed in the oscillator code because once the aliasing has 
happened it can't be filtered out afterwards.

> Maybe this is just something I'm not understanding due to being a
> programmer with an interest in synthesis rather than a signal analyst
> with a knowledge of programming?

No worries.  There are some excellent papers discussing this particular 
challenge of digital synthesis if you are keen to learn more:

https://ccrma.stanford.edu/~stilti/papers/blit.pdf

http://www.cs.cmu.edu/~eli/papers/icmc01-hardsync.pdf

http://www.musica.ed.ac.uk/wp-content/uploads/Manual_Upload/Valimaki-Virtual-analog.pdf

-Richie, 



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