[PD] [iemlib] filter click

[julien.breval at tremplin-utc.net]

hello

Still trying to make a block-shaped filter from a HP filter and a LP filter,
with the possibility of changing the cutoff frequencies as fast as possible, I
experimented some patches with Iemlib's Chebychev and Butterworth filters, and
also [lp1~]. 
The sound is very good (especially, the 10th order filters have a very fitting
slope), but I get a sound "artefact" when I change the cutoff, unless the time
interpolation is superior to 30 ms -- which is already too much for my patch (I
want to use this filter inside a kind of realtime granular editing software). 
Is there a solution to avoid this ? For the moment, the original [vcf~] is the
only one I found that can have its cutoff changed very fast. But besides this
"triangle" shape I would like to add a "rectangle" filter to my patch.

-j