[linux-audio-dev] XAP: Pitch control

[David Olofson]

On Wednesday 11 December 2002 00.29, Steve Harris wrote:
> On Tue, Dec 10, 2002 at 09:10:01PM +0100, David Olofson wrote:
> > What I'm trying to say is that (1/12)/note certainly doesn't look
> > nice in note oriented code, considering that there's *not*
> > nescessarilly 12 notes per octave:
>
> No, but if theres not 12 notes per octave then you dont need a
> twelve... in 12tET were dealing with 12ths of octaves, so I dont
> htink the 12 will be at all supprising.

You're missing that I'm not talking about 1.0/octave, linear pitch, 
but <something>/note, *note* pitch. That means <something>/note 
should *always* apply, and that <something> should be constant. 
Changing it is totally pointless, since you'd still have note pitch.

Changing the "size" of one note is about as silly as changing the 
"size" of one octave; that's my whole point. (1/12)/note for note 
pitch *is* just as silly as 12.0/octave for linear pitch.


> > ...and to avoid both that *and* have 1.0/octave for linear pitch,
> > we have to do actual conversions whenever connecting these two
> > different kinds of controls.
>
> Well, thats unavoidable for the general case. But, as we know the
> converter for 12tET is trivial.
>
> > The only sensible way of doing that is by using some form of
> > conerter plugins, IMHO. I definitely do not want to force host
> > callbacks into this.
>
> OK, fine, no host callbacks. The host could do implicit conversion
> though it doesn't have to virtually insert a plugin. But this is
> probably a per-host design decistion, it doesn't have to go in the
> API.

Right.

Some plugins think in 1.0/note, and others in 1.0/octave. If you want 
to connect them, you'll need "something" that expresses 1.0/note as 
1.0/octave according to your scale of choice. Just as if you were 
going to connect a MIDI controller to a CV synth.


> Some users (eg. me ;) will probably want to insert there own
> custom scale converter plugins anyway.

Exactly! :-)


//David Olofson - Programmer, Composer, Open Source Advocate

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