Re: [Denemo-devel] Denemo Hooks

[Richard Shann]

On Tue, 2011-06-28 at 00:16 +0200, Nils Gey wrote:
> > Hmm, I'm not totally convinced that looking at the key signature would
> > be a good overall strategy to decide enhamonic selection. I.e. in the
> > key of A minor, how would you select between C# (often in cadences on
> > the final with major third - so called 'picardian third') and Db (as
> > the minor six above the forth degree in the bass - neapolitan sixt)? I
> > could come quite a lot of similar probematic cases. I _do_ agree that
> > it would be nice to have some way of controlling enharmonic selection,
> > and selection by key signature would be a good default candidate.  For
> > my use-cases, being able to manually switch the "tonal center" would
> > be fine.
> 
> 
> Then please tell a few of the other reasons.
> Picardian third is a not a problem. The natural order of notes is the pillar 
> of fifths. cis is much nearer than des so its an obvious choice. This also 
> reflects musical practise.
> The neapolitan sixt of the subdominant is not something needed very often 
> compared to the major third of the tonic. 
> Its also obvious in A minor if its <e gis b> or <e as b> (Dominant), which is 
> Gis because its 5 steps away and As is 7. 
> 
> The obvious problem here is 6 steps, which is the tritone interval in both 
> directions. Here math can't help but it should be the higher variant (Dis in 
> A minor) because Es conflicts with the natural fifths of a minor which is 
> very unlikely that anybody wants that regulary.
> 
> The last time I thought about this I came across very few cases where there 
> is no obvious choice. I would be able to program a system to check the music 
> while playing so that you get both C# and Db when you need it, but this 
> requires a lot more work and there are more urgent things to do.
> 
> Modulations are of course a problem, especially if you follow a more 
> traditional way and not change the keysig. 
In fact, I intend for this implementation to be less mathematical and
more pragmatic. I will limit the shifting of the tonal centre on the
basis that the pieces I am interested in will likely modulate sharpwise
if they are in extremely flat keys and vice versa. The framework will be
there for others to use in other ways (the beauty of scheme) of course.

Richard

> 
> In Denemos case there are some options:
>       -Shifting functions like we have currently. Those could be relative to 
> the keysig in the future
>       -No-Lilypond Keysigs that can be placed anywhere so that the score has 
> more theoretical background and logic in Denemo. 
>       -Analysis of the surrounding music in real time. Possible but maybe not 
> worth the work yet.
> 
> 
> Nils