Sorry excuse me for coming in half way through this conversation...

Another thing you could consider is the elliptical (IIR I think) filter
available in cmix - although the original code used a fortran coeff
algorithm there are C versions floating around (I can dig up a cleaned f2c
version is someone is interested in dealing with it). This filter allows lp,
bp or hp configurations with good time/accuracy trade-offs.

Ross.

>>>where
>>>iftype : filtertype 1=Butterworth,2=Chebychev,3=Bessel
>>>ibandtype : Bandtype 1=Lowpass , 2=Highpass, 3=Bandpass, 4=Bandstop
>>>iripple : ripple in dB for Chebychev filter
>>>iorder : order of filter
>>>icorner1 : cornerfrequency 1
>>>icorner2 = cornerfrequency 2, for Bandpass/Bandstop filters
>>>
>>>the opcode would then at inittime design the filter and maybe show
>>>a graphic output of freq ,phase and impulse response.
>>>
>>>at http://www.cs.york.ac.uk/~fisher/mkfilter/ there is an online
>>>interactive filter design page.
>>>The source code is available to download too, but I haven't found
anything
>>>about license.
>>>If this is interesting one could off course ask the author if it's okay
>>>to use his sources in csound.
>>>
>>>Roger K
>
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>Erik Spjut (spyoot, rhymes with cute) - Associate Professor of Engineering
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