Re: Microtonal midi output

[Jean Abou Samra]

Le 08/05/2021 à 20:33, brahim.pro a écrit :
> Hello,
>
> I would like to define a scale, let's say A minor, and slightly change 
> the frequency of the notes in the output MIDI file. I have trouble 
> finding this feature in the documentation. So does this feature exist 
> and how to do that?
>
> Thanks,
>
> Brahim


Hello,

You can always implement it in Scheme... Something like this,
tampering with the pitches:

\version "2.22.0"

tuneMIDI =
#(define-music-function (scale music) (list? ly:music?)
   (for-some-music
     (lambda (m)
       (let ((pitch (ly:music-property m 'pitch)))
         (if (ly:pitch? pitch)
             (let* ((tones (ly:pitch-tones pitch))
                    (r (ly:moment-main
                         (ly:moment-mod
                           (ly:make-moment tones 0)
                           (ly:make-moment 6 0))))
                    (offset (assv-ref scale r)))
               (ly:message "~s" r)
               (if offset
                   (let* ((transpose-pitch (ly:make-pitch 0 0 offset))
                          (new-pitch (ly:pitch-transpose pitch 
transpose-pitch)))
                     (ly:music-set-property! m 'pitch new-pitch)
                     #t)
                   #f))
             #f)))
     music)
   music)

myNotes = \relative { a b c d e f gis a b c d e f gis a }

{ \myNotes }

\score {
  \tuneMIDI
    #'(
       ; Lower F (5/2 tones above C) by 1/10 tone.
       (5/2 . -1/10)
       ; Raise G# by 1/10 tone.
       (4 . 1/10)
       )
    \myNotes
  \midi { }
}

Note how this requires separating out MIDI generation in
a dedicated \score block.

I was told that my email client inserts non-breaking
spaces in my code examples. If this happens and you
can't compile the file, please use the attachment.

Best,
Jean

midi-frequency.ly
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