@c -*- coding: utf-8; mode: texinfo; -*-
@ignore
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@node Repeats
@section Repeats

Repetition is a central concept in music, and multiple notations
exist for repetitions.

@menu
* Writing repeats::             
* Other repeats::               
@end menu

@node Writing repeats
@subsection Writing repeats

Blah blah

@menu
* Normal repeats::              
* Repeat syntax::               
* Manual repeat commands::      
* Repeats and MIDI::            
@end menu

@node Normal repeats
@unnumberedsubsubsec Normal repeats

@cindex volta
@cindex prima volta
@cindex seconda volta
@funindex \repeat

Normal repeats, with or without alternate repeats, may be printed:

@lilypond[quote,ragged-right,fragment,verbatim,relative=2]
\repeat volta 2 { c4 d e f }
\repeat volta 2 { g f e d }
  \alternative {
    { cis2 g' }
    { cis,2 b }
  }
c1
@end lilypond

Repeats with upbeats may be created.

@lilypond[quote,ragged-right,fragment,verbatim,relative=2]
\new Staff {
  \partial 4 e |
  \repeat volta 4 { c2 d2 | e2 f2 | }
  \alternative { { g4 g g e } { a a a a | b2. } }
}
@end lilypond

@noindent
or

@lilypond[quote,ragged-right,fragment,verbatim,relative=2]
\new Staff {
  \partial 4 
  \repeat volta 4 { e | c2 d2 | e2 f2 | }
  \alternative { { \partial 4*3 g4 g g } { a a a a | b2. } }
}
@end lilypond


@funindex \repeatTie

Ties may be added to a second ending,

@lilypond[quote,ragged-right,fragment,verbatim,relative=2]
c1
\repeat volta 2 {c4 d e f ~ }
\alternative { {f2 d} {f\repeatTie f,} }
@end lilypond

It is possible to shorten volta brackets by setting
@code{voltaSpannerDuration}.  In the next example, the bracket
only lasts one measure, which is a duration of 3/4.

@lilypond[verbatim,ragged-right,quote]
\relative c''{
  \time 3/4
  c c c
  \set Score.voltaSpannerDuration = #(ly:make-moment 3 4)
  \repeat volta 5 { d d d }
  \alternative { { e e e f f f }
  { g g g } }
}
@end lilypond

If you want to start a repeat at the beginning of a line and have
a double bar at the end of the previous line, use

@example
@dots{} \bar "||:" \break 
\repeat volta 2 @{ @dots{} 
@end example

see @ref{Bar lines} for more information.

@seealso

Snippets: @lsrdir{repeats}

Internals Reference: @internalsref{VoltaBracket},
@internalsref{RepeatedMusic},
@internalsref{VoltaRepeatedMusic}, and
@internalsref{UnfoldedRepeatedMusic}.

Examples:

Brackets for the repeat are normally only printed over the topmost
staff.  This can be adjusted by moving @code{Volta_engraver} to
the Staff context where you want the brackets to appear; see
@ref{Modifying context plug-ins} and
@lsr{repeats,volta@/-multi@/-staff@/.ly}.


@refbugs

@cindex repeat, ambiguous

A nested repeat like

@example
\repeat @dots{}
\repeat @dots{}
\alternative
@end example

@noindent
is ambiguous, since it is is not clear to which @code{\repeat} the
@code{\alternative} belongs.  This ambiguity is resolved by always
having the @code{\alternative} belong to the inner @code{\repeat}.
For clarity, it is advisable to use braces in such situations.

Timing information is not remembered at the start of an
alternative, so after a repeat timing information must be reset by
hand; for example, by setting @code{Score.measurePosition} or
entering @code{\partial}.  Similarly, slurs or ties are also not
repeated.



@node Repeat syntax
@unnumberedsubsubsec Repeat syntax

@cindex repeats

LilyPond has one syntactic construct for specifying different
types of repeats.  The syntax is

@example
\repeat @var{variant} @var{repeatcount} @var{repeatbody}
@end example

If you have alternative endings, you may add
@funindex \alternative
@example
\alternative @{
  @var{alternative1}
  @var{alternative2}
  @var{alternative3}
  @dots{}
@}
@end example

@noindent
where each @var{alternative} is a music expression.  If you do not
give enough alternatives for all of the repeats, the first
alternative is assumed to be played more than once.

The following types of repetition are supported

@table @code
@item unfold
Repeated music is fully written (played) out.  This is useful when
entering repetitious music.  This is the only kind of repeat that
is included in MIDI output.

@item volta
Repeats are not written out, but alternative endings (volte) are
printed, left to right with brackets.  This is the standard
notation for repeats with alternatives.  These are not played in
MIDI output by default.


@item tremolo
Make tremolo beams.  These are not played in MIDI output by
default.

@item percent
Make beat or measure repeats.  These look like percent signs.
These are not played in MIDI output by default.  Percent repeats
must be declared within a @code{Voice} context.

@end table


@node Manual repeat commands
@unnumberedsubsubsec Manual repeat commands

@funindex repeatCommands

The property @code{repeatCommands} can be used to control the
layout of repeats.  Its value is a Scheme list of repeat commands.

@table @asis
@item @code{start-repeat}
Print a @code{|:} bar line.

@item @code{end-repeat}
Print a @code{:|} bar line.

@item @code{(volta @var{text})}
Print a volta bracket saying @var{text}: The text can be specified
as a text string or as a markup text, see @ref{Text markup}.  Do
not forget to change the font, as the default number font does not
contain alphabetic characters;

@item @code{(volta #f)}
Stop a running volta bracket.
@end table

@lilypond[quote,ragged-right,verbatim,fragment,relative=2]
c4
  \set Score.repeatCommands = #'((volta "93") end-repeat)
c4 c4
  \set Score.repeatCommands = #'((volta #f))
c4 c4
@end lilypond


@seealso

Snippets: @lsrdir{repeats}

Internals Reference: @internalsref{VoltaBracket},
@internalsref{RepeatedMusic}, @internalsref{VoltaRepeatedMusic},
and @internalsref{UnfoldedRepeatedMusic}.

@node Repeats and MIDI
@unnumberedsubsubsec Repeats and MIDI

@cindex expanding repeats
@funindex \unfoldRepeats

With a little bit of tweaking, all types of repeats can be present
in the MIDI output.  This is achieved by applying the
@code{\unfoldRepeats} music function.  This function changes all
repeats to unfold repeats.

@lilypond[quote,verbatim,fragment,line-width=8.0\cm]
\unfoldRepeats {
  \repeat tremolo 8 {c'32 e' }
  \repeat percent 2 { c''8 d'' }
  \repeat volta 2 {c'4 d' e' f'}
  \alternative {
    { g' a' a' g' }
    {f' e' d' c' }
  }
}
\bar "|."
@end lilypond

When creating a score file using @code{\unfoldRepeats} for MIDI,
it is necessary to make two @code{\score} blocks: one for MIDI
(with unfolded repeats) and one for notation (with volta, tremolo,
and percent repeats).  For example,

@example
\score @{
  @var{..music..}
  \layout @{ .. @}
@}
\score @{
  \unfoldRepeats @var{..music..}
  \midi @{ .. @}
@}
@end example


@node Other repeats
@subsection Other repeats

@menu
* Tremolo repeats::             
* Tremolo subdivisions::        
* Measure repeats::             
@end menu

@node Tremolo repeats
@unnumberedsubsubsec Tremolo repeats

@cindex tremolo beams

To place tremolo marks between notes, use @code{\repeat} with
tremolo style

@lilypond[quote,verbatim,ragged-right]
\new Voice \relative c' {
  \repeat tremolo 8 { c16 d16 }
  \repeat tremolo 4 { c16 d16 }
  \repeat tremolo 2 { c16 d16 }
}
@end lilypond

Tremolo marks can also be put on a single note.  In this case, the
note should not be surrounded by braces.

@lilypond[quote,verbatim,ragged-right]
\repeat tremolo 4 c'16
@end lilypond

Similar output is obtained using the tremolo subdivision,
described in @ref{Tremolo subdivisions}.


@seealso

In this manual: @ref{Tremolo subdivisions}, @ref{Repeats}.

Snippets: @lsrdir{repeats}

Internals Reference: @internalsref{Beam},
@internalsref{StemTremolo}.


@node Tremolo subdivisions
@unnumberedsubsubsec Tremolo subdivisions

@cindex tremolo marks
@funindex tremoloFlags

Tremolo marks can be printed on a single note by adding
@q{@code{:}[@var{number}]} after the note.  The number indicates
the duration of the subdivision, and it must be at least 8.  A
@var{length} value of 8 gives one line across the note stem.  If
the length is omitted, the last value (stored in
@code{tremoloFlags}) is used

@lilypond[quote,ragged-right,verbatim,fragment]
c'2:8 c':32 | c': c': |
@end lilypond


@refbugs

Tremolos entered in this way do not carry over into the MIDI
output.


@seealso

In this manual: @ref{Tremolo repeats}.

Snippets: @lsrdir{repeats}

Elsewhere: @internalsref{StemTremolo}.


@node Measure repeats
@unnumberedsubsubsec Measure repeats

@cindex percent repeats
@cindex measure repeats

In the @code{percent} style, a note pattern can be repeated.  It
is printed once, and then the pattern is replaced with a special
sign.  Patterns of one and two measures are replaced by
percent-like signs, patterns that divide the measure length are
replaced by slashes.  Percent repeats must be declared within a
@code{Voice} context.

@lilypond[quote,verbatim,ragged-right]
\new Voice \relative c' {
  \repeat percent 4 { c4 }
  \repeat percent 2 { c2 es2 f4 fis4 g4 c4 }
}
@end lilypond

Measure repeats of more than 2 measures get a counter, if you
switch on the @code{countPercentRepeats} property,

@lilypond[relative=2,fragment,quote,verbatim,ragged-right]
\new Voice {
\set countPercentRepeats = ##t
  \repeat percent 4 { c1 }
}
@end lilypond



Isolated percents can also be printed.  This is done by putting a
multi-measure rest with a different print function,

@lilypond[fragment,verbatim,quote]
\override MultiMeasureRest #'stencil
  = #ly:multi-measure-rest::percent
R1
@end lilypond




@seealso

Snippets: @lsrdir{repeats}

Internals Reference: @internalsref{RepeatSlash},
@internalsref{PercentRepeat}, @internalsref{DoublePercentRepeat},
@internalsref{DoublePercentRepeatCounter},
@internalsref{PercentRepeatCounter},
@internalsref{PercentRepeatedMusic}.