Re: [Linuxsampler-devel] Envelopes , filtering and zipper noise

[Benno S. <be...@ga...>]

Hi,
the shapes do look nice, I was wondering about two things:
What the ideal coefficients would be so that very fast envelopes can
be achieved while slower ones are smoothed out so that no zipper noise 
is audibile.
BTW since in most of cases (in absence of envelopes) the LP smoothing is
not needed, it would be wise to skip that code (to save cycles) when the
envelope reached the final point (up to a very small epsilon since we
are talking of exponentials). What do you suggest here ?

Regarding adding a let's say resonant LP filter to the sample output:
I guess the coefficients need to be smoothed out in some way too,
otherwise zipper noise will probably show up again.
I've found these interesting msgs on the saol-users list but I do not
have a deep understanding of the things mentioned in these mails.

http://sound.media.mit.edu/mpeg4/saol-users/0179.html
http://sound.media.mit.edu/mpeg4/saol-users/0178.html

What would a good tradeoff for achieving low-CPU usage zippernoise-free
filter modulation would be ? (some kind of interpolation of precomputed
coefficients ?)

Benno


On Thu, 2002-11-14 at 13:28, Steve Harris wrote:
> Hi all,
> 
> Benno and I were discussing envelope generation last night, I think that
> the right way to generate an exponential envelope (I checked some synths
> outputs too and it looks like this is that way its done) is to feed a
> constant value into a LP filter with different parameters for each stage.
> 

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