Scordatura

[Jean Abou Samra]

Bonjour Martial,

Suite à ta question à la fondue Lily en visio tout à l'heure,
je propose une solution pour obtenir un rendu MIDI adapté à
la scordatura :



\version "2.23.9"

#(set-object-property! 'scordaturaTuning 'translation-type? list?)

%% Converted from articulations.cc
#(use-modules (ice-9 match))
#(define (articulation-list note-events articulation-events type)
   (let loop ((note-events note-events)
              (articulation-events articulation-events)
              (acc '()))
     (match note-events
       (()
        (reverse! acc))
       ((note-event . rest)
        (let ((found (find (lambda (ev)
                             (memq type (ly:event-property ev 'class)))
                           (ly:event-property note-event 'articulations))))
          (cond
           (found
            (loop rest
                  articulation-events
                  (cons found acc)))
           ((pair? articulation-events)
            (loop rest
                  (cdr articulation-events)
                  (cons (car articulation-events)
                        acc)))
           (else
            (loop rest
                  '()
                  (cons '() acc)))))))))


#(define (Scordaturize_performer context)
   (let ((note-evs '())
         (string-number-evs '())
         (fingering-evs '()))
     (make-performer
      (listeners
       ((note-event engraver event)
        (set! note-evs (cons event note-evs)))
       ((string-number-event engraver event)
        (set! string-number-evs (cons event string-number-evs)))
       ((fingering-event engraver event)
        (set! fingering-evs (cons event fingering-evs))))
      ((pre-process-music engraver)
       (let* ((tab-strings (articulation-list note-evs 
string-number-evs 'string-number-event))
              (defined-fingers (articulation-list note-evs 
fingering-evs 'fingering-event))
              (func (ly:context-property context 'noteToFretFunction))
              (string-fret-finger (func context note-evs (list 
tab-strings defined-fingers)))
              (scordatura-tuning (ly:context-property context 
'scordaturaTuning)))
         (for-each
          (lambda (ev elems)
            (match-let*
                  (((string-number fret-number _) elems)
                   (tuning-base (list-ref scordatura-tuning (1- 
string-number)))

                   ;; Don't care about enharmony, it's about MIDI.
                   (fret-diff (ly:make-pitch 0 0 (* 1/2 fret-number)))
                   (sounding-pitch (ly:pitch-transpose tuning-base 
fret-diff)))
              (ly:event-set-property! ev 'pitch sounding-pitch)))
          note-evs
          string-fret-finger)))
      ((stop-translation-timestep engraver)
       (set! note-evs '())
       (set! string-number-evs '())
       (set! fingering-evs '())))))

\midi {
  \context {
    \Voice
    \consists #Scordaturize_performer
    noteToFretFunction = #determine-frets
    predefinedDiagramTable = ##f
    stringTunings = #guitar-tuning
  }
}

mus = {
  \clef bass
  e, fis, a, b, d e g a b cis' e' fis'
  a,\6
}

\score {
  \new Staff \with {
    scordaturaTuning = \stringTuning <e fis b e' b' e''>
  } \mus
  \midi { }
  \layout { }
}

\new TabStaff \mus


Cordialement,
Jean