Issue 5164: Doc: Add usage of OpenType font feature

[lilypond.git] / Documentation / notation / keyboards.itely

@c -*- coding: utf-8; mode: texinfo; -*-
@ignore
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    When revising a translation, copy the HEAD committish of the
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@end ignore

@c \version "2.19.25"

@node Keyboard and other multi-staff instruments
@section Keyboard and other multi-staff instruments

@lilypondfile[quote]{keyboard-headword.ly}

This section discusses several aspects of music notation that are
unique to keyboard instruments and other instruments notated on
many staves, such as harps and vibraphones.  For the purposes of
this section this entire group of multi-staff instruments is called
@qq{keyboards} for short, even though some of them do not have a
keyboard.

@menu
* Common notation for keyboards::
* Piano::
* Accordion::
* Harp::
@end menu

@node Common notation for keyboards
@subsection Common notation for keyboards

This section discusses notation issues that may arise for most
keyboard instruments.

@menu
* References for keyboards::
* Changing staff manually::
* Changing staff automatically::
* Staff-change lines::
* Cross-staff stems::
@end menu

@node References for keyboards
@unnumberedsubsubsec References for keyboards

@cindex piano staves
@cindex staves, piano
@cindex staves, keyboard instruments
@cindex staves, keyed instruments
@cindex keyboard instrument staves
@cindex keyed instrument staves
@cindex keyboard music, centering dynamics
@cindex dynamics, centered in keyboard music
@cindex piano music, centering dynamics
@cindex centered dynamics in piano music

@funindex PianoStaff

Keyboard instruments are usually notated with Piano staves.  These
are two or more normal staves coupled with a brace.  The same
notation is also used for other keyed instruments.
Organ music is normally written with two staves inside a
@code{PianoStaff} group and third, normal staff for the pedals.

The staves in keyboard music are largely independent, but
sometimes voices can cross between the two staves.  This
section discusses notation techniques particular to keyboard
music.

Several common issues in keyboard music are covered elsewhere:

@itemize

@item Keyboard music usually contains multiple voices and the
number of voices may change regularly; this is described in
@ref{Collision resolution}.

@item Keyboard music can be written in parallel, as described in
@ref{Writing music in parallel}.

@item Dynamics may be placed in a @code{Dynamics} context,
between the two @code{Staff} contexts
to align the dynamic marks on a horizontal line
centered between the staves; see @ref{Dynamics}.

@item Fingerings are indicated with @ref{Fingering instructions}.

@item Organ pedal indications are inserted as articulations, see
@ref{List of articulations}.

@item Vertical grid lines can be shown with @ref{Grid lines}.

@item Keyboard music often contains @notation{Laissez vibrer} ties
as well as ties on arpeggios and tremolos, described in
@ref{Ties}.

@item Placing arpeggios across multiple voices and staves is
covered in @ref{Arpeggio}.

@item Tremolo marks are described in @ref{Tremolo repeats}.

@item Several of the tweaks that can occur in keyboard music are
demonstrated in @rlearning{Real music example}.

@item Hidden notes can be used to produce ties that cross voices,
as shown in @rlearning{Other uses for tweaks}.

@end itemize

@c @snippets
@c @lilypondfile[verbatim,quote,texidoc,doctitle]
@c {forcing-visibility-of-systems-with-multi-bar-rests-when-using-\RemoveEmptyStaffContext.ly}
@c http://lsr.di.unimi.it/LSR/Item?u=1&id=312

@seealso
Learning Manual:
@rlearning{Real music example},
@rlearning{Other uses for tweaks}.

Notation Reference:
@ref{Grouping staves},
@ref{Instrument names},
@ref{Collision resolution},
@ref{Writing music in parallel},
@ref{Fingering instructions},
@ref{List of articulations},
@ref{Grid lines},
@ref{Ties},
@ref{Arpeggio},
@ref{Tremolo repeats}.

Internals Reference:
@rinternals{PianoStaff}.

Snippets:
@rlsr{Keyboards}.


@node Changing staff manually
@unnumberedsubsubsec Changing staff manually

@cindex changing staff manually
@cindex manual staff changes
@cindex staff changes, manual
@cindex cross-staff notes
@cindex notes, cross-staff
@cindex cross-staff beams
@cindex beams, cross-staff

@funindex \change

Voices can be switched between staves manually, using the command

@example
\change Staff = @var{staffname}
@end example

@noindent
The string @var{staffname} is the name of the staff.  It switches
the current voice from its current staff to the staff called
@var{staffname}.  Typical values for @var{staffname} are
@code{"up"} and @code{"down"}, or @code{"RH"} and @code{"LH"}.

The staff to which the voice is being switched must exist at the
time of the switch.  If necessary, staves should be @qq{kept alive},
see @ref{Keeping contexts alive}.

Cross-staff notes are beamed automatically:

@lilypond[verbatim,quote]
\new PianoStaff <<
  \new Staff = "up" {
    <e' c'>8
    \change Staff = "down"
    g8 fis g
    \change Staff = "up"
    <g'' c''>8
    \change Staff = "down"
    e8 dis e
    \change Staff = "up"
  }
  \new Staff = "down" {
    \clef bass
    % keep staff alive
    s1
  }
>>
@end lilypond

If the beaming needs to be tweaked, make any changes to the stem
directions first.  The beam positions are then measured from the
center of the staff that is closest to the beam.  For a simple
example of beam tweaking, see @rlearning{Fixing overlapping
notation}.

@cindex cross-staff collisions
@cindex collisions, cross-staff voices

Overlapping notation can result when voices cross staves:

@lilypond[verbatim,quote]
\new PianoStaff <<
  \new Staff = "up" {
    \voiceOne
    % Make space for fingering in the cross-staff voice
    \once\override DynamicLineSpanner.staff-padding = #4
    e''2\p\< d''\>
    c''1\!
  }
  \new Staff = "down" <<
    {
      \clef bass
      s4. e,8\rest g,2\rest
      c1
    } \\ {
      c8\( g c'
      \change Staff = "up"
      e' g' b'-3 a' g'\)
      f'1
    }
  >>
>>
@end lilypond

The stem and slur overlap the intervening line of dynamics
because automatic collision resolution is suspended for beams, slurs
and other spanners that connect notes on different staves,
as well as for stems and articulations if their placement is
affected by a cross-staff spanner.
The resulting collisions must be resolved manually, where necessary,
using the methods in @rlearning{Fixing overlapping notation}.

@seealso
Learning Manual:
@rlearning{Fixing overlapping notation}.

Notation Reference:
@ref{Stems},
@ref{Automatic beams},
@ref{Keeping contexts alive}.

Snippets:
@rlsr{Keyboards}.

Internals Reference:
@rinternals{Beam},
@rinternals{ContextChange}.

@knownissues
Beam collision avoidance does not work for automatic beams that end
right before a change in staff.  In this case use manual beams.


@node Changing staff automatically
@unnumberedsubsubsec Changing staff automatically

@cindex changing staff automatically
@cindex automatic staff changes
@cindex staff changes, automatic

@funindex \autochange
@funindex PianoStaff

Voices can be made to switch automatically between the top and the
bottom staff.  The syntax for this is

@example
\autochange @dots{}@var{music}@dots{}
@end example

@noindent
This will create two staves inside the current staff group
(usually a @code{PianoStaff}), called @code{"up"} and
@code{"down"}.  The lower staff will be in the bass clef by default.
The autochanger switches on the basis of the pitch (middle@tie{}C is the
turning point), and it looks ahead skipping over rests to switch
in advance.

@lilypond[quote,verbatim]
\new PianoStaff {
  \autochange {
    g4 a b c'
    d'4 r a g
  }
}
@end lilypond

@noindent
It is possible to specify other pitches for the turning point.
If the staves are not instantiated explicitly, other clefs may be used.

@lilypond[quote,verbatim]
music = {
  g8 b a c' b8 d' c'8 e'
  d'8 r f' g' a'2
}

\autochange d' \music
\autochange b \with { \clef soprano } \music
\autochange d' \with { \clef alto } \with { \clef tenor } \music
@end lilypond

@cindex relative music and autochange
@cindex autochange and relative music

@funindex \relative

A @code{\relative} section that is outside of @code{\autochange}
has no effect on the pitches of the music, so if necessary, put
@code{\relative} inside @code{\autochange}.

If additional control is needed over the individual staves, they
can be created manually with the names @code{"up"} and
@code{"down"}.  The @code{\autochange} command will then switch
its voice between the existing staves.

@warning{If staves are created manually, they @emph{must} be named
@code{"up"} and @code{"down"}.}

For example, staves must be created manually in order to place a
key signature in the lower staff:

@lilypond[quote,verbatim]
\new PianoStaff <<
  \new Staff = "up" {
    \new Voice = "melOne" {
      \key g \major
      \autochange \relative {
        g8 b a c b d c e
        d8 r fis, g a2
      }
    }
  }
  \new Staff = "down" {
    \key g \major
    \clef bass
  }
>>
@end lilypond

@seealso
Notation Reference:
@ref{Changing staff manually}.

Snippets:
@rlsr{Keyboards}.

Internals Reference:
@rinternals{AutoChangeMusic}.


@knownissues
@cindex chords, splitting across staves with \autochange

The staff switches may not end up in optimal places.  For high
quality output, staff switches should be specified manually.

Chords will not be split across the staves; they will be assigned to a
staff based on the first note named in the chord construct.


@node Staff-change lines
@unnumberedsubsubsec Staff-change lines

@cindex staff-change line
@cindex staff change line
@cindex cross-staff line
@cindex cross staff line
@cindex line, staff-change follower
@cindex line, cross-staff
@cindex line, staff-change
@cindex follow voice
@cindex voice, following
@cindex staff switching
@cindex cross-staff

@funindex followVoice
@funindex \showStaffSwitch
@funindex \hideStaffSwitch

Whenever a voice switches to another staff, a line connecting the
notes can be printed automatically:

@lilypond[quote,verbatim]
\new PianoStaff <<
  \new Staff = "one" {
    \showStaffSwitch
    c'1
    \change Staff = "two"
    b2 a
  }
  \new Staff = "two" {
    \clef bass
    s1*2
  }
>>
@end lilypond


@predefined
@code{\showStaffSwitch},
@code{\hideStaffSwitch}.
@endpredefined

@seealso
Snippets:
@rlsr{Keyboards}.

Internals Reference:
@rinternals{Note_head_line_engraver},
@rinternals{VoiceFollower}.


@node Cross-staff stems
@unnumberedsubsubsec Cross-staff stems

@cindex cross-staff notes
@cindex cross staff notes
@cindex notes, cross-staff
@cindex cross-staff stems
@cindex cross staff stems
@cindex stems, cross-staff
@cindex chords, cross-staff
@cindex cross-staff chords
@cindex cross staff chords

@funindex Stem
@funindex \crossStaff
@funindex \autoBeamOff
@funindex Span_stem_engraver

Chords that cross staves may be produced using the
@code{Span_stem_engraver}. Care must be taken to ensure that
automatic beams do not beam the notes on one staff when it’s not
required on the other.

@lilypondfile[verbatim,quote]
{cross-staff-stems.ly}

For the time being, this engraver can not be specified by its name in
double quotes, but rather prefixing its name with a hash symbol
@code{#}, due to the way it is implemented.

@snippets
@lilypondfile[verbatim,quote,texidoc,doctitle]
{indicating-cross-staff-chords-with-arpeggio-bracket.ly}

@seealso
Snippets:
@rlsr{Keyboards}.

Internals Reference:
@rinternals{Stem}.


@node Piano
@subsection Piano

This section discusses notation issues that relate most directly to the
piano.

@menu
* Piano pedals::
@end menu

@node Piano pedals
@unnumberedsubsubsec Piano pedals

@cindex piano pedals
@cindex pedals, piano
@cindex sustain pedal
@cindex pedal, sustain
@cindex sostenuto pedal
@cindex pedal, sostenuto
@cindex una corda
@cindex tre corde
@cindex sos.
@cindex U.C.

@funindex \sustainOn
@funindex \sustainOff
@funindex \sostenutoOn
@funindex \sostenutoOff
@funindex \unaCorda
@funindex \treCorde

Pianos generally have three pedals that alter the way sound is
produced: @notation{sustain}, @notation{sostenuto}
(@notation{sos.}), and @notation{una corda} (@notation{U.C.}).
Sustain pedals are also found on vibraphones and celestas.

@lilypond[quote,verbatim]
\relative {
  c''4\sustainOn d e g
  <c, f a>1\sustainOff
  c4\sostenutoOn e g c,
  <bes d f>1\sostenutoOff
  c4\unaCorda d e g
  <d fis a>1\treCorde
}
@end lilypond

@cindex pedal indication styles
@cindex pedal indication, text
@cindex pedal indication, bracket
@cindex pedal indication, mixed
@cindex pedal sustain style
@cindex sustain pedal style

@funindex pedalSustainStyle
@funindex mixed
@funindex bracket
@funindex text

There are three styles of pedal indications: text, bracket, and mixed.
The sustain pedal and the una corda pedal use the text style by default
while the sostenuto pedal uses mixed by default.

@lilypond[quote,verbatim]
\relative {
  c''4\sustainOn g c2\sustainOff
  \set Staff.pedalSustainStyle = #'mixed
  c4\sustainOn g c d
  d\sustainOff\sustainOn g, c2\sustainOff
  \set Staff.pedalSustainStyle = #'bracket
  c4\sustainOn g c d
  d\sustainOff\sustainOn g, c2
  \bar "|."
}
@end lilypond

The placement of the pedal commands matches the physical movement of the
sustain pedal during piano performance.  Pedalling to the final bar line
is indicated by omitting the final pedal off command.

Pedal indications may be placed in a @code{Dynamics} context,
which aligns them on a horizontal line.

@seealso
Notation Reference:
@ref{Ties}.

Snippets:
@rlsr{Keyboards}.

Internals Reference:
@rinternals{SustainPedal},
@rinternals{SustainPedalLineSpanner},
@rinternals{SustainEvent},
@rinternals{SostenutoPedal},
@rinternals{SostenutoPedalLineSpanner},
@rinternals{SostenutoEvent},
@rinternals{UnaCordaPedal},
@rinternals{UnaCordaPedalLineSpanner},
@rinternals{UnaCordaEvent},
@rinternals{PianoPedalBracket},
@rinternals{Piano_pedal_engraver}.


@node Accordion
@subsection Accordion

@cindex accordion

This section discusses notation that is unique to the accordion.

@menu
* Discant symbols::
@end menu

@node Discant symbols
@unnumberedsubsubsec Discant symbols

@cindex accordion discant symbols
@cindex discant symbols, accordion
@cindex accordion shifts
@cindex accordion shift symbols

Accordions are often built with more than one set of reeds that may be
in unison with, an octave above, or an octave below the written pitch.
Each accordion maker has different names for the @notation{shifts} that
select the various reed combinations, such as @notation{oboe},
@notation{musette}, or @notation{bandonium}, so a system of symbols has
come into use to simplify the performance instructions.

@snippets

@lilypondfile[verbatim,quote,texidoc,doctitle]
{accordion-register-symbols.ly}

@seealso
Snippets:
@rlsr{Keyboards}.


@node Harp
@subsection Harp

This section discusses notation issues that are unique to the harp.

@menu
* References for harps::
* Harp pedals::
@end menu

@node References for harps
@unnumberedsubsubsec References for harps
@cindex harps
@cindex bisbiglando

Some common characteristics of harp music are covered elsewhere:

@itemize

@item The glissando is the most characteristic harp technique,
@ref{Glissando}.

@item A @notation{bisbigliando} is written as a tremelo @ref{Tremolo
repeats}.

@item Natural harmonics are covered under @ref{Harmonics}.

@item For directional arpeggios and non-arpeggios, see @ref{Arpeggio}.

@end itemize

@seealso
Notation Reference:
@ref{Tremolo repeats},
@ref{Glissando},
@ref{Arpeggio},
@ref{Harmonics}.


@node Harp pedals
@unnumberedsubsubsec Harp pedals

@cindex harp pedals
@cindex harp pedal diagrams
@cindex pedals, harp
@cindex pedal diagrams, harp

Harps have seven strings per octave that may be sounded at the natural,
flattened, or sharpened pitch.  In lever harps, each string is adjusted
individually, but in pedal harps every string with the same pitch name
is controlled by a single pedal.  From the player's left to right, the
pedals are D, C, and B on the left and E, F, G, and A on the right.
The position of the pedals may be indicated with text marks:

@lilypond[quote,verbatim,fragment]
\textLengthOn
cis''1_\markup \concat \vcenter {
  [D \flat C \sharp B|E \sharp F \sharp G A \flat] }
c''!1_\markup \concat \vcenter {
  [ C \natural ] }
@end lilypond

or pedal diagrams:

@lilypond[quote,verbatim,fragment]
\textLengthOn
cis''1_\markup { \harp-pedal #"^v-|vv-^" }
c''!1_\markup { \harp-pedal #"^o--|vv-^" }
@end lilypond

The @code{\harp-pedal} command accepts a string of characters, where
@code{^} is the highest pedal position (flattened pitch), @code{-} is
the middle pedal position (natural pitch), @code{v} is the lowest pedal
position (sharpened pitch), and @code{|} is the divider.  A prefixed
@code{o} will circle the following pedal symbol.

@seealso
Notation Reference:
@ref{Text scripts},
@ref{Instrument Specific Markup}.