block filters (was Re: [PD] [erratum] question about [lop~] and [hip~])

[julien.breval at tremplin-utc.net]

Actually, I am making a kind of brick-shaped band pass filter, as an alternative
to [vcf~] which has a triangular shape. If this kind of filter already exists in
a library, I will use it but I haven't found anything yet. 
The first solution is to use first a series of [lop~] and to pass it into a
series of [hip~]. I still have some DSP problems with all this when I change the
frequencies (I got surprisingly high levels sometimes). Maybe another solution
is to use a kind of narrow filter bank using some [vcf~], but it's not very easy
to control as I would need lots of filters, like in FFTs.
The FFT is not a good solution here either, because time precision is very
important.

> > > I may want to change the cutoff very fast, with big jumps
> > 
> > hmm, this is worrying then.
> > Are there not any low-pass or high-pass filters in the latest iemlib that
> > take signal inputs for the cutoff freqs?  I'm sorry, I haven't got Pd
> here
> > at work, so I can't check.  But I must say I HAVE noticed clicks even
> using
> > the control (ie. non signal) version of [line].  
> 
> that's what I feared actually
> 
> > I think my block size was
> > 64, but whatever this value is the output from [line] will always be a
> > significant jump compared to using [line~] - unless you make the [line]
> > change REALLY slowly of course!
> 
> I will try to use [line] with a very small time grain
> 
> 
> thanks for your help
> 
> -j
> 


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