[linux-audio-dev] Re: chebychev

[Steve Harris]

On Thu, Oct 31, 2002 at 05:21:08 -0800, Bill Schottstaedt wrote:
> > there's one problem i see: if we employ a chebyshev, it is going
> > to create harmonics no matter what amplitude our incoming signal
> > [...]
> > it seems hard to come up with a wave shaper that favours higher
> > harmonics,[...]
> 
> I have only been skimming this discussion, but these caught my eye,
> and I'm wondering what you mean by "chebychev" here.  If you're
> driving a sum Chebychev polynomials with the original signal, none of
> these statements is necessarily correct -- you can preload a table
> with the polynomials, so the computational load can be unrelated to the
> harmonic content; the content will depend on the input amplitude; high
> harmonics are easy -- just emphasize the relevant polynomial --
> probably I don't know what you're talking about.

No, we are talking about the same thing, but the computational cost of
evaluating the chebychev depends on the order of the polynomial and
therefore the number of harmincs you want to generate.

The "it seems hard to come up with a wave shaper that favours higher
harmonics" quote was refering to waveshapers other than chebychev derived
ones.

However the reason we aren't using cheby's at the moment is because we
currently have a problem with too many harmonics, rather than too few.

- Steve