Re: [LAD] Prototyping algorithms and ideas

On Fri, Feb 01, 2008 at 07:37:33PM +0100, Albert Graef wrote:

> > But what about resampling? The main main signal usually needs to
> > be resampled up 5-10 times to get a decent sound. Can I do that
> > with faust? Something like:
> >
> > process = resample(5,d)
>
> I want that, too. :) There's no (easy) way to do resampling inside Faust
> right now, because Faust doesn't support multirate processing yet. I
> know that Yann has this on his TODO list, as we already discussed it
> last summer. Once multirate processing is there, adding samplerate
> conversion (either programmed in Faust or by calling an external C
> routine) shouldn't be a big deal any more.

Won't be easy I'd think. Both resampling and fractional
sample delay lead to the same problem with different
constraints - interpolation. And you can't do high quality
interpolation without delay: the simple fact is that
the value halfway between two samples depends on _all_
the samples, past and future. The dependency goes down
with distance and you can ignore it at some point. Yet
for good results at 48 kHz you need at least something
like 24 samples forward and back. There is no such thing
as 'instant' resampling, which is what you would want
if it's part of a language. Any resample operator would
need to have an 'arbitrary' delay built-in...

Ciao,

-- 
FA
Laboratorio di Acustica ed Elettroacustica
Parma, Italia
Lascia la spina, cogli la rosa.
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