Re: unfoldRepeats for midi

[Mark Polesky]

Paul Scott wrote:
> It doesn't work.  At first I didn't use \unfoldRepeats for the
> graphical output as you show above.  But adding the
> \unfoldRepeats to the first (graphical) part the graphical music
> is unfolded in a strange way.  The graphical music is generated
> with the repeat signs omitted but nothing unfolded.  The music
> would be 16 bars long and it is but the last 6 bars are blank.


Okay, I looked into this, and here's what I've learned.

> global = { \repeat volta 2 s1*6 \alternative { { s1*2 } { s1*2 } } }

Change s1*6 to { s1*6 }. The \repeat syntax is
  \repeat volta repeatcount musicexpr
and all music expressions require curly braces.


> \score {
> <<
>   \new Staff = soprano <<
>     \context Voice = soprano { << { \unfoldRepeats \global } \melody >> }
>   >>
> >>
> \layout{ }
> }

If you're going to use \unfoldRepeats in a \score with \layout, it
doesn't make sense to apply it to only one music expression if
there are other simultaneous expressions. Since \global and
\melody are simultaneous expressions, move \unfoldRepeats outside:

\score {
  <<
  \new Staff = soprano
    <<
    \context Voice = soprano
      \unfoldRepeats { << \global \melody >> }
    >>
  >>
  \layout{ }
}

However, it may make even more sense to apply \unfoldRepeats to
the whole score, so you don't have to keep applying it to other
voices (should there be any)...

\score {
  \unfoldRepeats
  <<
  \new Staff = soprano
    <<
    \context Voice = soprano { << \global \melody >> }
    >>
  >>
  \layout{ }
}

Also consider Staff and Voice naming. Are you going to have
non-soprano Voices in the soprano Staff? If not, you probably
don't need the \context Voice = soprano since a Voice context is
implicitly created with any music expression (though there are
reasons for explicitly instantiating the Voice context). Either
way (and honestly I don't know if this makes a difference), I
wouldn't want two different contexts with the same name, even if
they are nested within each other. You might consider sopranoStaff
and sopranoVoice, for instance.

Also, << and >> are only needed when there's more than one
simultaneous expression. So if sopranoStaff will only contain
sopranoVoice, you could do this:

\score {
  \unfoldRepeats
  <<
  \new Staff = sopranoStaff
    \context Voice = sopranoVoice { << \global \melody >> }
  >>
  \layout { }
}

And if << and >> enclose simultaneous expressions which already
have curly braces built into their definition -- like \global and
\melody do, you don't need an extra pair of curly braces around
the << >>.

\score {
  \unfoldRepeats
  <<
  \new Staff = sopranoStaff
    \context Voice = sopranoVoice << \global \melody >>
  >>
  \layout { }
}

I've left the outer << >> with the assumption that other voices
will eventually be added, but if not, you could remove those too.

Unfortunately, after all this, I've learned that \unfoldRepeats
doesn't natively work when the repeats are in an expression
separate from the notes, even if they're funneled together before
calling \unfoldRepeats. See
http://lists.gnu.org/archive/html/lilypond-devel/2009-06/msg00161.html
for a response to my post on the developers mailing-list regarding
this question.

So you must do something like this:

global = { \key d \major }
melody = \relative c' {  
  \repeat volta 2 {
    fs2 fs4. fs8
    g4 fs e d
    d2( ~ d8 e8 d4)
    a2 a8 b d4
    fs e2.
    fs4 e d e
  }
  \alternative {
    {
      fs2 ~ fs8 g fs4
      e1
    } {
      e8 d ~ d2. ~
      d1
    }
  }
}

\score {
  \unfoldRepeats
  <<
  \new Staff = sopranoStaff
    \context Voice = sopranoVoice << \global \melody >>
  >>
  \layout { }
}

Also, in your \score with the \midi block, you have this line:
> \new Score{ << { \unfoldRepeats \global } \melody >> }

I don't think \new Score is used anymore. You could reduce this
line to 

  \unfoldRepeats 
  <<
  \melody
  >>

I've left the << >> with the assumption that other voices will 
eventually be added, and if so, consider renaming "melody" to
something like "sopMusic". If "melody" is the only voice, then of
course you don't need the << >>, and you can just do

  \unfoldRepeats \melody


\score {
  \unfoldRepeats 
  <<
  \melody
  >>
  \midi {
    \context {
      \Score tempoWholesPerMinute = #(ly:make-moment 120 4)
    }
  }
}

Also, use \new instead of \context when a Voice first appears. Not
strictly necessary, but in complex scores, it's helpful to be able
to find the first instance of a specific context.

One last note: it may save space to put a lot of notes on one line
in your ly file, but it's easier for others to read your code if
it's nicely indented.

I've attached a working version of the file.

HTH.
- Mark

unfold-repeats.ly
Description: Text Data