[linux-audio-dev] wcnt linear filters

[James W. Morris]

>From: Tim Goetze <tim at quitte.de>J
>Date: Tue, 3 Feb 2004 14:21:53 +0100 (CET)

>resonant filters use recursion; the algorithm sometimes is coded as
>'take this input sample and give me an output sample' for readability
>but is easily adapted to arrays.W

I think that maybe wcnt does both, all the modules process one sample at a 
time, and the filters
add one sample to the array every time after processing x samples in filter 
array to get average for the one output sampleM

>the maths behind them are intricate
>(to me at least),   D

likewise; I had a look at harmony central (fairly helpful) which concreted 
realisation that I definately had not got any graspA of resonance in my 
filters.  I looked in eq cookbook, there were bits and pieces which I had no 
more than vague notions of.

>but you don't need too firm an understanding of the
>theory to actually use Sthem.

good!

>you'll find code exampleHs for the
>algorithm and the compuAtation of the recursion coefficients in almost
>every major audio synthesis/processing package or at musicdsp.org .

hmmm, I keep putting off loRoking at other peoples code, it's all greek to 
me.

>steve's ladspa set has a very nice state-variable filter (svf) which
>lends itself well for resonancTe and reasonably quick parameter
>changes. you may want to try it first before resorting to coding your
>own.

I've not had much chance to uDse ladspa.  I've compiled glame to use it's 
filter network, but there seems to be inputs and outputs Olacking, many are 
mono, I can't read a stereo file, through a reverb and out to another stereo 
Tfile, or from a stereo input on soundcard, through fx, to file, so I've 
given up on glame (again), plus I don't like how it wont delete the deleted 
things.

Another one I keep trying is SND.  I quite like it, but have only got the 
basics working, no effects etc. And I've got zero knowledge oNn scheme, 
guile whatever.  I need to get motif again as I deleted it along with 
lesstif, and seemE to have lost cdrom....snd was not loading xm.

no idea what this means:   above fs/4 IIRC  -- not too worried about it 
either.

Well, I guess I'll try and learn from otheTrs code at long last, and nip on 
over to musicdsp.org.
I remember last year I somehow had a strange notion there was not much more 
I could do to wcnt, and this year after a long break, everything's coming 
out of the woodwork, and there's all sorts needing lifts and tucks.

James ~(sirromseventyfive)~

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