Subject: Re: Fwd: Re: [linux-audio-dev] XAP: Pitch control
From: David Olofson (david_AT_olofson.net)
Date: Thu Dec 12 2002 - 21:16:07 EET
On Thursday 12 December 2002 15.26, Steve Harris wrote:
> On Thu, Dec 12, 2002 at 01:46:29PM +0100, David Olofson wrote:
> > > and arpegiate for non ET scales is a hard
> > > problem anyway, providing note numbers doesn't help.
> >
> > Yes it does, since you need to deal *only* with the note number.
> > The scale converter then generates the correct pitch for the
> > notes in the scale that you reference. That's the whole point
> > with using note_pitch and scale converters at all.
>
> I dont think that arpegiation from a non ET scale will fall exactly
> on a note anyway - though I'd have to think about that.
Why wouldn't it? It sure does if you *play* the arpeggio on a real
instrument...
> I guess it
> depends what key you're in... which can't be expressed in a note
> number anyway, so I still think its redundant.
Well, then we're into this "tweaking notes for better harmonies"
thing again... That's indeed hairy stuff, and plugins that want to
actually *do* that (rather than just switching between whatever notes
they get in an input chord) will have to understand quite a bit more
than notes. You'll need to either operate entirely in linear pitch,
or hint the plugin a little about what scale you're using. The latter
is what a MIDI solution would do (unless it just assumes 12tET), but
obviously, it's rather silly to do it that way if you can just work
in the linear_pitch domain, after the scale converter, instead. After
all, *perfect* harmonies are not strictly bound to scales anyway.
> Now I think about it you wouldn't want to do arpegiation using note
> numbers, what you're interested in the the pitch coefficient to get
> the correct harmonic relation.
In some cases, yes - but remember that the arpeggiator is not the
*only* plugin in the system. If you play other synths as well, you'll
probably want the arpeggiator to respect the scales used for those,
rather than trying to find "perfect" harmonies all on it's own. With
notes + scales, you make this trivial, even with non-ET scales, since
all you have to do is use the same scale everywhere.
//David Olofson - Programmer, Composer, Open Source Advocate
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