Re: transpositions within a global key setting.

[David Wright]

On Tue 10 Dec 2019 at 07:41:07 (+0100), Urs Liska wrote:
> Am 09.12.19 um 15:24 schrieb N. Andrew Walsh:
> > let us say I have a piece where I want to specify the key
> > signature once for all instruments. I have something like the
> > following:
> > 
> > \version = 2.19.82
> > global= {
> >  \key f \minor
> >  \time 4/8
> >   }
> > %% (and whatever other settings I want)
> > 
> > oDAMusic = \transpose a c {
> >    \relative c''' {
> >      \key as \minor
> >      {{MUSIC}}
> >    }
> > }
> 
> What this code is trying to convey (different from your intentions)
> that MUSIC is some music in as minor that is then transposed to f
> minor.
> 
> What you *need* to say is that the music is in f minor (because that
> is your key signature) but transposed *for display* to as minor. It
> should immediately strike you as odd when you seem to need to write
> \key as \minor when you are not actually having polytonality.
> 
> So the key signature in your music should be the f minor specified in
> the global variable (note BTW that it is not ideal practice naming a
> variable "global"),

But both the LM and NR use this convention frequently; the former
recommends it (§3.2.3).

> and you can simply include that *within* the music
> expression rather than in teh staff definition.

I don't see how that works for anything beyond the trivial, for example:

global = { % with original pagination
  \key f \major
  \time 2/2
  s1 * 3 \break
  s1
  \repeat volta 2 {
    s1 * 3 \break
    s1 * 3 \break
  } \alternative {
    {
      s1 * 2
    } {
      s1 \break
      s1
    } }
  s1 * 3 \break
  \pageBreak
  s1 * 5 \break
  s1 * 3 \break
  s1 * 3 \break
  s1 * 2
  \bar "||"
  \key c \major
  s1 \break
  s1 * 3 \break
  \pageBreak
  s1 * 3 \break
  s1 * 3 \break
  s1 * 3 \break
  s1 * 3 \break
  \bar "||"
  \key df \major
  s1 * 3 \break
  \pageBreak
  s1 * 3 \break
  s1 * 2
  \bar "||"
  \key f \major
  s1 \break
  s1 * 3 \break
  s1 * 3 \break
  s1
  \bar "||"
  s1 s2
  \bar "|."
}

#(set-global-staff-size 18)
\book {
  \bookOutputSuffix "2staves"
  \score {
    \transpose f f
    \new ChoirStaff <<
      \new Staff = stop \with { \consists Bar_number_engraver } <<
        \clef treble \global
        \new Voice { \accident \voiceOne \soprano }
        \addlyrics \with { alignAboveContext = stop } { \sopranofrag }
        \new Voice { \accident \voiceTwo \alto }
        \addlyrics { \altotext }
        \addlyrics { \altotextii }
      >>
      \new Staff = sbot <<
        \clef "bass^8" \global
        \new Voice { \accident \voiceOne \tenor }
        \addlyrics \with { alignAboveContext = sbot } { \tenorfrag }
        \new Voice { \accident \voiceTwo \bass }
        \addlyrics { \bassfrag }
      >>
    >>
    \layout {
      \context {
        \Score
        \remove Bar_number_engraver
      }
    }
  }
}

> You define the music in the original key and then transpose it to the
> key you want it displayed in. If you are dealing with MIDI output (and
> even if not you should consider it) you can then use \transposition to
> re-transpose the MIDI output without affecting the engraved key and
> pitches (see 
> http://lilypond.org/doc/v2.19/Documentation/notation/displaying-pitches#instrument-transpositions
> (which is where you should have looked at)).
> 
> This is what you want to do:
> 
> \version  "2.19.82"
> global= {
>   \key f \minor
>   \time 4/8
> }
> 
> oDAMusic =
> \transpose f as
> \relative c' {
>   \transposition a
>   \global
>   f g as
> }
> 
> \score {
>   \new Staff = "Staff_oboeDA" <<
>     \oDAMusic
>   >>
> }
> 
> > \score {
> > \new Staff = "Staff_oboeDA" <<
> >       \global \oDAMusic
> >     >>
> > }
> > 
> > I've omitted other variables, instrument blocks, and settings. My
> > question is what to do about this instrument, the oboe d'amore,
> > which transposes. According to the NR, here:
> > 
> > http://lilypond.org/doc/v2.19/Documentation/notation/changing-multiple-pitches#transpose
> > 
> > I would need to format the block like this to print the correct
> > key signature. When I do this, however, Lily throws an error about
> > "Two simultaneous key-change events" and that one will be junked.
> > Score output, however, looks fine, with the transposition and
> > key-signature correct.
> > 
> > As a general question, how should I be formatting this so that I
> > don't get an error?

Cheers,
David.