Re: Does anybody do MIDI splitting?

[David Kastrup]

Thomas Morley <thomasmorley65@gmail.com> writes:

> Am Mo., 18. Okt. 2021 um 16:14 Uhr schrieb David Kastrup <dak@gnu.org>:
>>
>>
>> Hi,
>>
>> currently entering drum scores for the ensemble I am playing in (getting
>> a note-savvy living drummer for regular practice is comparatively
>> challenging) and I frequently have the situation that there are large
>> pauses in drum play.  At that point in time, I need to cut the MIDI
>> file, take everything up to the last note before the pause into one file
>> and start the next file on beat 1 (sometimes 3) leading to the next note
>> (interestingly, if the next note is on beat 2 or 4 or similar, you still
>> need to start on 1 or 3 since otherwise the "drummer" fails to convey
>> right away the tempo they as opposed to everyone else is aiming for).
>>
>> It's cumbersome writing separate variables and scores manually; it would
>> be nicer to just drop the cutting points in the middle of the score
>> (like in the separate time track) and then some automated thing would
>> slice the score into separate scores for MIDI.
>>
>> Has anybody done anything like that already?
>>
>> --
>> David Kastrup
>>
>
> Years ago I made
> https://archiv.lilypondforum.de/index.php/topic,2012.msg12471.html#msg12471
> Not exactly what you want, maybe a starting point...

Essentially, something like

#(set-object-property! 'segmentKey 'translation-type? key?)

segmentStart =
#(define-music-function (k) (key?)
   #{ \tag midi \context Score \applyContext
  #(lambda (c)
    (set! (ly:context-property c 'skipTypesetting)
                         (not (eqv? (ly:context-property c 'segmentKey) k))))
   #})

segmentStop = \tag midi \set skipTypeSetting = ##t

timeI =
{
  \segmentStart 0
  \time 4/4
  \tempo "Maesto marziale" 4 = 104
  \skip 1*30
  \segmentStart 1
  \mark "A"
  \time 3/4
  \tempo "Allegretto" 4 = 152
  \skip 2.*2 \skip 4
}

[...]

$@(map
(lambda (n)
#{
\score {
  \header
  {
    title = "Rossini"
  }
  \keepWithTag midi
  \new Score \with { segmentKey = #n }
  \articulate << \new DrumStaff  \with { midiInstrument = "orchestra kit" } 
\drumpartI
                 \new Staff  \with { midiInstrument = "timpani" } \timpanipartI
                 \context Staff \timeI
               >>
  \midi {
    \midifixes
  }
}
#}) (iota 2))

appears to do the trick.  Obviously, this is not a minimal example, with
lots of content missing.  And squeezing in the "segmentKey" via a score
property seems rather awkward.

So: <https://gitlab.com/lilypond/lilypond/-/merge_requests/967>

Allows doing it through the \midi block.

-- 
David Kastrup