Re: spurious partial in 2nd repeat abc->ly

[Lukas-Fabian Moser]

Hi Joe,

But there is still something wrong with my understanding.  When I compile the attached with 2.22, Lily complains of a barcheck fail at 15,30 :-(

This is caused by \unfoldRepeats in the MIDI version of the score and the conflicting simultaneous \partials you issue in mill_mill_o (begins with \partial 8*2) and mill_mill_o_chords (begins with \partial 8).

Ultimately, the reason is your non-standard (or by usual standards "wrong") notation of a repeat.

    a) \partial makes the current bar "shorter than usual". You only
    have to issue this once in simultaneous layers of music (for
    example, only in the melody, not also in the chords). It's not wrong
    to issue it in each simultaneous layer, but to have \partial 8 and
    \partial 8*2 (which is \partial 4, by the way) simultaneously makes
    no sense.

b) In classical notation, your repeat would have to be considered "wrong" since, at the point where we encounter the :|| sign, we already are at the end of a complete 4/4 bar. The new pickup bar in effect creates a 5/4 bar mid-piece, which is not impossible, but very unusual (and should be written explicitly if really intended).

A standard way of writing repeats in music with pickups (common, for example, in Bach's chorales) would be:

\version "2.22.0"

\relative c' {
  \repeat volta 2 {
    \partial 4
    c8 d |
    e4 e d d |
    c2.
  } e8 d |
  e4 e8 f g4 f8 e
  e4( d)^"etc."
}

Note that the last bar inside the \repeat is incomplete (c2.), but together with the new pickup (c8 d in the repeat, e8 d afterwards) makes for a complete bar.

Lukas