[pd] biquad~ yet again

[david golightly]

Thanks, Carmen, that's really informative - exactly what I'm looking for.

David


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homepage:
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>From: carmen <ix at replic.net>
>To: pd-list at iem.at
>Subject: Re: [pd] biquad~ yet again
>Date: Mon, 7 Nov 2005 22:10:24 +0000
>
>On Mon, Nov 07, 2005 at 04:51:19PM -0500, david golightly wrote:
> > Hey list,
> >
> > I just did a search in the list-archive and, yes, I realize that there 
>was
> > a dicussion on biquad~ back in April, but the thread referred to a link
> > that is now broken.  Suffice to say, it seems the programming of this
> > external could be a bit more user-friendly, targeted toward the people 
>who
> > are likely to actually USE pd, not people with advanced degrees in math.
> > (If you fall into both categories, more power to ya).  If I could just 
>get
> > some help here, I'd like:
> >
> > f(x, a) = (ff1, ff2, ff3, fb1, fb2)
> > where these are the biquad coefficients for x = notch frequency and a =
> > attenuation
> >
> > While I understand how it's useful to have tools for building filters in
> > any DSP software, it's too bad this isn't also wrapped up as a more
> > straightforward notch filter.
>
>it is, see /externals/ggee/filters in CVS.. theres a helper object for most 
>of the RBJ biquad types.. i also pasted his formules into a tk script, 
>http://whats-your.name/pd/gui/filter.gif see /extensions/gui/ix/filter.wid.
>
>
>and no, i dont understand the math either, has somethign to do with 
>rectangular-to-polar conversions i think (but for some reason at least in 
>the commercial filter plugins which use biquad its never shown this way)..
>
> > Or maybe I'm just being a wuss here.  I'm
> > sure there's someone out there who could implement this as an external.
> >
> > Thanks,
> >
> > David
> >
> >
> > -  ---=---^---   -^-  -=- - - ^------ - -^---^-  -- --^^  --===
> >
> > homepage:
> > http://www.davidgolightly.net
> >
> >
> >
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