Recognise anacrusis in MuseScore, from Lilypond's midi files

Question

I generate midi files in LilyPond and import them into MuseScore for playback.

When there is an anacrusis in the piece, I use LilyPond's \partial command:

\version "2.21.0"
\score {
    {
        \time 4/4
        \partial 4
%  0
            a'8 b' |
%  1
        c''4 4 4 c''8 b' |
%  2
        a'4 4 4 
        \bar "||"
    }
    \layout {}
    \midi {}
}

Compiling the code generates a midi file. Opening this file with MuseScore will render the score, and a "MIDI import panel" will also pop up. Several settings (such as "MuseScore instrument", "Max. Quantisation", etc.) can be adjusted, then clicking "Apply" will re-import the file.

The setting called:
"Recognise anacrusis" [English (GB)] / "Recognize pickup measure" [English (US)]
seems like it should be just what I need to get the anacrusis to render correctly, but it doesn't work. Whether selected or not, MuseScore continues to render the score as if there isn't an anacrusis.

LilyPonds \partial command apparently isn't effecting the midi file in a way that MuseScore understands.

---

I do know how to fix the anacrusis manually:

• Selecting everything, and Cutting,
• Right clicking the first measure and selecting "Bar Properties" / "Measure Properties",
• Changing the setting in "Bar Duration" / "Measure Duration" - "Actual" (e.g. from 4/4 to 1/4),
• Then Pasting everything back in.

This works, but is so tedious.

---

To get MuseScore's "Recognise anacrusis" setting to work, I need to change the LilyPond code:

I have to explicitly write a "bar" with a time signature that corresponds to the length of the anacrusis, and then set the real time signature for the first complete bar. (This makes the \partial command unnecessary.)

To get the pdf to look right, I also have to adjust their appearance of the time signature, and to set the first bar number to zero.

\version "2.21.0"
\score {
    {
        \time 1/4
        \set Staff.timeSignatureFraction = 4/4
        \set Score.currentBarNumber = #0
%  0
            a'8 b' |
%  1
        \time 4/4
        c''4 4 4 c''8 b' |
%  2
        a'4 4 4 
        \bar "||"
    }
    \layout {}
    \midi {}
}

This does work; the code compiles, the pdf is accurate, and MuseScore can recognise the anacrusis. But my problems with this method are, that it isn't really right from a music theory perspective (it's not a bar of 1/4), and it's compromising my LilyPond code.

Why won't LilyPond's \partial command effect the midi file in a way that MuseScore's "Recognise anacrusis" setting will understand?

Is there a simpler way to get MuseScore to understand an anacrusis from LilyPond?

Answer 1

Unfortunately LilyPond's \partial command doesn't actually encode the anacrusis into the midi file. This is because midi files don't even have a way to encode a "real" anacrusis.

This leaves either of the workaround solutions suggested in the question.
The second solution posed in the question (using a bar with a reduced time signature at the start of the piece) is probably the best method, because it works in LilyPond, looks fine in the pdf, and is exactly what MuseScore's "Recognise Anacrusis" is looking for.

I'm not sure why LilyPonds's partial function doesn't implement an anacrusis in the way that MuseScore will recognise, but it doesn't.