Automatically change durations

shiftDurations can be used to change the note lengths of a piece of music.

It takes two arguments – the scaling factor as a power of two, and the number of dots to be added as a positive integer.

\version "2.24"

music = \relative c'' { a1 b2 c4 d8 r }

{
  \time 4/2
  \music
  \time 4/4
  \shiftDurations 1 0 \music
  \time 2/4
  \shiftDurations 2 0 \music
  \time 4/1
  \shiftDurations -1 0 \music
  \time 8/1
  \shiftDurations -2 0 \music
  \time 6/2
  \shiftDurations 0 1 \music
  \time 7/2
  \shiftDurations 0 2 \music
}