[linux-audio-dev] wcnt linear filters

[Tim Goetze]

James W. Morris wrote:

>>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

whatever you need to do to get the job done .. but it's usually
better to unify.

>>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.

the cookbook is a bitch to read without the background. i guess it's
meant to serve as a quick lookup sheet for people who know the stuff
but can't remember the exact numbers. if you're looking for bi-quads,
those in ecasound seem to follow the cookbook iirc.

>>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.

that's not good, if i may say so. use the source, luke ... you know
that drill. there's truth to it. read it, dig it, make it yours.

>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.

why not implement ladspa support in your application? it's quite
simple to do, and opens a world of sound manipulation.

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

1/4 sampling rate, or 11 kHz in a 44 kHz system. i'm not worried about
it either since i never run the svf even near that high a cutoff
frequency.

>Well, I guess I'll try and learn from otheTrs code at long last, and nip on
>over to musicdsp.org.

yes! do so. :)

tim