25 Aug
2013
25 Aug
'13
12:24 a.m.
[Fons Adriaensen]
I'm planning to evade this problem by crossfading between two parallel
static filters. Some phase mismatch issues can probably be expected
when the parameter sweep covers a larger range, but I'm hopeful it
will turn out not to be much of a problem in actual practice, and that
we will find out soon. It really needs a fix.
Tim
I've learned to mute monitoring while doing such
tests...
I was suspecting you had :)
It adds to the
evidence that implementing thorough control
smoothening is inevitable in the long run.
That may or not solve the problem. You have 3 input parameters
(P), and 5 biquad coefficients (C). Interpolating the C can
make a biquad unstable, and if this happens it doesn't matter
how fast or slow you do it. The only solution is to interpolate
the C only between sets of values that correspond to values of
the P that are not too far apart. So you need two levels, first
on the P to limit the rate of change of the parameters, then on
the C to avoid zipper noise.