Hi,
You won't be able to fade between two filtered blocks of complex
(non-sinusoidal) input to the same effect as modulating an arbitrary
single filter's frequency. That said, when modulating an IIR filter such
as a biquad (as shown in your second email's link), you should not need
to compute the z-transform. You may simply modulate the biquad's
parameters repeatedly, and unless you're doing something unusual with
respect to calculating those parameters, the cost will be relatively
low.
Best,
Ariadne Lewis-Towbes
On 2023-04-25 20:37, Yisheng Jiang wrote:
I’m trying to render a note that feed into a IIR filter (2-3 poles)
whose cutoff frequency following an envelope generator, and it’s not
possible for me to compute the z-transform parameters every rendering
block..
Is it approximately the same to generate two pcm streams with the
starting and ending cutoff frequencies, then cross fade them to make
the resultant sound?
