Re: scorditura (or "string-specific transposition")

[Graham Percival]

On 1-Aug-04, at 1:31 AM, Han-Wen Nienhuys wrote:
> address@hidden writes:
> > I know how to display the new tuning for a stringed instrument.  Can
> > Lilypond (almost certainly via scheme) print the noteheads correctly?
> > I mean, can the lilypond input file be written in C, and have
> > Lilypond/scheme transpose only the appropriate notes?
>
> you will need a scheme function for that.
> look at input/test/smart-transpose for inspiration.

Thanks!  For the list archives, here's how to do it:

As it happened, all I had to do was add three lines to the
top of the (naturalise-pitch p) function:

   (cond
     ((or (< o -1) (and (= o -1) (< n 4)))
      (set! a (+ a 2))))

pseudocode: if the note is low enough (a low octave, or the right octave
but a note below G -- F, E, D, or C), then make the note sharp.
(the existing code takes care of making a B# into a C and the like)


Here's my complete test file; again for future googling or maillist
archive searching:

\version "2.3.8"

#(define  (naturalise-pitch p)
  (let* ((o (ly:pitch-octave p))
         (a (ly:pitch-alteration p))
         (n (ly:pitch-notename p)))

   (cond
     ((or (< o -1) (and (= o -1) (< n 4)))
      (set! a (+ a 2))))

    (cond
     ((and (> a 1) (or (eq? n 6) (eq? n 2)))
      (set! a (- a 2))
      (set! n (+ n 1)))
     ((and (< a -1) (or (eq? n 0) (eq? n 3)))
      (set! a (+ a 2))
      (set! n (- n 1))))

    (cond
     ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
     ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))

    (if (< n 0) (begin (set!  o (- o 1)) (set! n (+ n 7))))
    (if (> n 6) (begin (set!  o (+ o 1)) (set! n (- n 7))))

    (ly:make-pitch o n a)))

#(define (naturalise music)
  (let* ((es (ly:music-property music 'elements))
         (e (ly:music-property music 'element))
         (p (ly:music-property music 'pitch)))

    (if (pair? es)
        (ly:music-set-property!
         music 'elements
         (map (lambda (x) (naturalise x)) es)))

    (if (ly:music? e)
        (ly:music-set-property!
         music 'element
         (naturalise e)))

    (if (ly:pitch? p)
        (begin
          (set! p (naturalise-pitch p))
          (ly:music-set-property! music 'pitch p)))

    music))

music =  \relative c' { b4 a g f | e d c b | b c d e | f g a b | }

\score {
   \context Staff {
        \clef alto
    \transpose c c \music
    \applymusic #naturalise \transpose c c \music
  }
}