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TODO – this section relies on overrides. We need to either add a predefined, move this to snippets (whole section), or violate policy for this section.
Feathered beams are used to indicate that a small group of notes
should be played at an increasing (or decreasing) tempo, without
changing the overall tempo of the piece. The extent of the
feathered beam must be indicated manually using [
and
]
, and the beam feathering is turned on by specifying a
direction to the Beam
property grow-direction
.
If the placement of the notes and the sound in the MIDI output
is to reflect the ritardando or accelerando indicated by the
feathered beam the notes must be grouped as a
music expression delimited by braces and preceded by a
featheredDurations
command which specifies the ratio
between the durations of the first and last notes in the group.
The square brackets show the extent of the beam and the braces show which notes are to have their durations modified. Normally these would delimit the same group of notes, but this is not required: the two commands are independent.
In the following example the eight 16th notes occupy exactly the same time as a half note, but the first note is one half as long as the last one, with the intermediate notes gradually lengthening. The first four 32nd notes gradually speed up, while the last four 32nd notes are at a constant tempo.
\override Beam #'grow-direction = #LEFT \featherDurations #(ly:make-moment 2 1) { c16[ c c c c c c c] } \override Beam #'grow-direction = #RIGHT \featherDurations #(ly:make-moment 2 3) { c32[ d e f] } % revert to non-feathered beams \override Beam #'grow-direction = #'() { g32[ a b c] }
The spacing in the printed output represents the note durations only approximately, but the midi output is exact.
The \featherDurations
command only works with very short
music snippets, and when numbers in the fraction are small.
Snippets: Rhythms.
This page is for LilyPond-2.11.58 (development-branch).
Report errors to http://post.gmane.org/post.php?group=gmane.comp.gnu.lilypond.bugs.
Your suggestions for the documentation are welcome.