Subject: Re: [linux-audio-dev] Re: [linux-audio-user] Bandlimited oscillator plugins for LADSPA ('blop-0.1.0')
From: mike rawes (mike_rawes_AT_yahoo.co.uk)
Date: Fri May 17 2002 - 16:37:02 EEST
--- Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk> wrote:
> On Fri, May 17, 2002 at 12:52:27 +0100, mike rawes
> wrote:
> > > How efficient are these techniques?
> >
> > At the moment, not very:
>
> That's pretty much what I do, except I dont use a
> tree, I use a large
> vector (so there are no duplicates) and a lookup
> table.
I don't have any duplicates either: each successive
table has a decreasing number of harmonics and less
samples per period - although the smallest tables
needed oversampling to remove noise at very high
frequencies. I was thinking of using a lookup table
too, using some multiple of (long)frequency as key.
My understanding of cubic splines is fairly poor, so I
don't know how to improve this (yet). I've used the
code from the musicdsp archives. Applying algrebraic
methods to reduce the number of multiplies is the best
I can do right now.
How do you do your speed tests?
Mike
>
> With gcc, linear interp it takes about 20 PIII
> cycles per sample, cubic
> takes about 50.
>
> I should use a faster cubic algorithm though.
>
> - Steve
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