Re: Lilypond's internal pitch representation and microtonal notation

[Carl Sorensen]

On 9/21/10 9:28 AM, "Joseph Wakeling" <address@hidden> wrote:

> On 09/21/2010 04:52 PM, Carl Sorensen wrote:
>> However, I was wrong in my assumption that something about the key signature
>> should determine which of the enharmonic equivalents should be used.
>> Instead, it appears that the neighboring notes should govern in tonal music.
>> In atonal music, it doesn't matter, except that it does in rapid passages.
>> There's virtually no guidance there that I can see for nontonal music.
> 
> Stone's guidance about the choice of accidentals is IMO something for
> composers to consider rather than Lilypond.  From a Lilypond point of
> view, the issue should simply be: the composer can have the accidentals
> s/he chooses.

This is true as long as the accidentals don't change with transposition.  If
the composer would choose different accidentals in a transposed piece, then
it becomes part of LilyPond's problem.
> 
>> Transposition of exact quarter tones into appropriate notation is likely to
>> remain a *very* tricky problem.
> 
> Why do you think so?  If you're transposing in a regular fashion (i.e.
> by a certain number of semitones) you just transpose the underlying
> notes and preserve the arrows.  If you want to transpose up/down by a
> quarter-tone, you just add an up/down-arrow to all the accidentals that
> don't already have one; all those that do, you bump them up/down to the
> next 'tonal' accidental.

This is true, as long as you are only transposing by a quarter tone.

What if you are transposing by a semitone plus a quarter tone?

And what about the finer gradations of tone, e/g 1/8 tone, etc.

You're clearly much more of an expert in this than I, so I may be wrong.
But it seems like handling quarter-tone accidentals is only easy if the
highest resolution on the transposition is a semitone.  And that may be the
case for practical music notation.  But it's not infinitely extendable, I
think.

> 
> The only thing you have to take into account is that you almost
> certainly need to convert double-sharps and flats to naturals of the
> staff pitches above and below respectively.  That requirement is one
> reason I've been trying to address Lilypond support for chromatic
> transposition recently.

Yes, I can see how this would work.

Thanks,

Carl