[linux-audio-dev] XAP: Control events

[Steve Harris]

On Wed, Dec 18, 2002 at 01:38:53 +0200, Sami P Perttu wrote:
> What about things like filter center frequency, isn't it "unnatural" to
> give these as logarithmic frequencies? Not to mention that most (?)

No, most synth processes use filters with pitch control, eg. modulation
with the envelope and pitch tracking.

A few modular synth filters have FM inputs as well, but its texception,
rather than the rule.

> plugins need to convert to Hz/samplerate anyway, involving an expensive
> exp(). Also, you can't specify negative frequencies in logarithmic Hz, and
> 0 Hz is the awkward minus infinity. But maybe they are not needed.

Yes, but if you do this inside the instrument then it only has to be done
once, if you send frequency data around then you have to keep converting
it back and forwards.

In any case there are well known optimisations for going from float pitch
to float Hz.

- Steve