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Changing time signatures inside a polymetric section using \scaleDurations

Flexible polymeter with unaligned measures

To support explicit creation of independently measured contexts, remove the Timing_translator from Score context and define a TimingStaffGroup context that has Timing_translator. This makes Timing an alias for TimingStaffGroup, targeting \time commands to the enclosing TimingStaffGroup.

Unlike LilyPond’s built-in \enablePerStaffTiming command, this approach requires the explicit creation of TimingStaffGroup contexts; in exchange, it allows creating multiple Staff contexts that jointly follow the measure defined in their enclosing TimingStaffGroup.

Locally scaled time signatures

Use the unscalable \time command to establish a measure of the desired length in Timing, a.k.a. TimingStaffGroup. In this snippet, all staves below TimingStaffGroup use a scaled time signature, so any time signature with the desired measure length is as good as any other. If there were an enclosed context that did not use a scaled time signature, the choice of time signature to set in Timing would matter in that context.

Use the \polymetric \time command to set scalable metric properties in contexts below Timing, and use the \scaleDurations command to scale both the local meter and the notes to fit the measure.

\layout {
  \context {
    \Score
    \remove "Timing_translator"
    \accepts TimingStaffGroup
  }
  \context {
    \StaffGroup
    \name TimingStaffGroup
    \alias StaffGroup
    \consists "Timing_translator"
  }
}

<<
  \new TimingStaffGroup <<
    \new Staff {
      \scaleDurations 8/5 {
        \time 6/5 % to set measure length in Timing
        \context Staff \polymetric \time 6/8
        b8 b b b b b
        \time 4/5 % to set measure length in Timing
        \context Staff \polymetric \time 2/4
        b4 b
      }
    }
  >>
  \new TimingStaffGroup <<
    \new Staff {
      \clef bass
      \time 2/4
      c2 d e f
    }
  >>
>>