Re: Midi: tremolo vs n:m

[Jean Abou Samra]

Le 16/10/2022 à 21:20, Benjamin Tordoff a écrit :
> Hi all,
>
> My understanding is that "\repeat tremolo 4 {c16}" and "c4:16"  should be 
> equivalent, the latter just being a (welcome) shortcut for the former. In the PDF output (without 
> expanding repeats) they look identical however in the midi playback (with repeats expanded) the 
> former plays as four semi-quavers but the latter as a single crotchet. This seems wrong.
>
> % This should produce 8 semi-quavers:
> \version "2.23.10"
> \score {
>         \unfoldRepeats {
>                 \repeat tremolo 4 {c'16}
>                 c'4:16
>         }
>         \midi {}
> }
>
> Is this a bug, or am I doing something wrong here?



Yes, this is a known issue,

https://gitlab.com/lilypond/lilypond/-/issues/6145

Here's a workaround you could use:

\version "2.23.14"

fixTremolos =
#(define-music-function (music) (ly:music?)
   (music-map
    (lambda (m)
      (let ((event (any (lambda (a)
                          (and (music-is-of-type? a 'tremolo-event)
                               a))
                        (ly:music-property m 'articulations))))
        (if event
            (let* ((total-tremolo-duration (ly:music-property m 'duration))
                   (tremolo-type (ly:music-property event 'tremolo-type))
                   (one-tremolo-note-duration (ly:make-duration 
(ly:intlog2 tremolo-type)))
                   (tremolo-note-count (/ tremolo-type (expt 2 
(ly:duration-log total-tremolo-duration)))))
              (set! (ly:music-property m 'duration)
                    one-tremolo-note-duration)
              (set! (ly:music-property m 'articulations)
                    (delete! event (ly:music-property m 'articulations)))
              (make-music 'TremoloRepeatedMusic
                          'repeat-count tremolo-note-count
                          'element m))
            m)))
    music))

unfoldRepeats = \unfoldRepeats #'() \fixTremolos \etc

%%%

music = { c'2:16 \repeat tremolo 8 c'16 }

\new Score <<
  \new Staff \music
  \new Staff \unfoldRepeats \music
>>



Best,
Jean