[LAD] Click-free fade-in algorithm for synths?

Fons Adriaensen fons at linuxaudio.org
Wed Sep 25 11:29:43 CEST 2019

On Tue, Sep 24, 2019 at 02:26:53PM -0600, Paul Davis wrote:
> There's fundamentally no such thing as a zero crossing. You might have two
> samples on either side of zero, but you still don't have a sample *at*
> zero, so in the general case, truncating one of them to zero and
> starting/ending there is still going to give you distortion and/or noise.
> Obviously there may be cases where one of them is close enough to zero for
> this not to be be an issue, but it's not a general method.

Even if you would have an exact zero sample, that would not avoid a
click. It would only ensure that the click has a 1/f^2 spectrum
instead of 1/f (so it would contain less HF).

>From a synth I'd expect a controllable and precisely defined fade-in,
not something that tries to be clever. If the fade-in time has to
depend on frequency (it usually does if the frequency can change over
a large range), that should be programmable or 'voltage controlled'
just as anything else.



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