Doc: clarify \header variables (2640)

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

@c -*- coding: utf-8; mode: texinfo; -*-

@ignore
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    When revising a translation, copy the HEAD committish of the
    version that you are working on.  For details, see the Contributors'
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@c \version "2.15.39"

@node General input and output
@chapter General input and output

This section deals with general LilyPond input and output issues,
rather than specific notation.

@menu
* Input structure::
* Titles and headers::
* Working with input files::
* Controlling output::
* MIDI output::
* Extracting musical information::
@end menu


@node Input structure
@section Input structure

The main format of input for LilyPond are text files.  By convention,
these files end with @file{.ly}.

@menu
* Structure of a score::
* Multiple scores in a book::
* Multiple output files from one input file::
* Output file names::
* File structure::
@end menu


@node Structure of a score
@subsection Structure of a score

@funindex \score

A @code{\score} block must contain a single music expression
delimited by curly brackets:

@example
\score @{
...
@}
@end example

@warning{There must be @strong{only one} outer music expression in
a @code{\score} block, and it @strong{must} be surrounded by
curly brackets.}

This single music expression may be of any size, and may contain
other music expressions to any complexity.  All of these examples
are music expressions:

@example
@{ c'4 c' c' c' @}
@end example

@lilypond[verbatim,quote]
{
  { c'4 c' c' c' }
  { d'4 d' d' d' }
}
@end lilypond

@lilypond[verbatim,quote]
<<
  \new Staff { c'4 c' c' c' }
  \new Staff { d'4 d' d' d' }
>>
@end lilypond

@example
@{
  \new GrandStaff <<
    \new StaffGroup <<
      \new Staff @{ \flute @}
      \new Staff @{ \oboe @}
    >>
    \new StaffGroup <<
      \new Staff @{ \violinI @}
      \new Staff @{ \violinII @}
    >>
  >>
@}
@end example

Comments are one exception to this general rule.  (For others see
@ref{File structure}.)  Both single-line comments and comments
delimited by @code{%@{ .. %@}} may be placed anywhere within an
input file.  They may be placed inside or outside a @code{\score}
block, and inside or outside the single music expression within a
@code{\score} block.

Remember that even in a file containing only a @code{\score} block, it
is implicitly enclosed in a \book block.  A \book block in a source
file produces at least one output file, and by default the name of the
output file produced is derived from the name of the input file, so
@file{fandangoforelephants.ly} will produce
@file{fandangoforelephants.pdf}.

(For more details  about @code{\book} blocks, see
@ref{Multiple scores in a book},
@ref{Multiple output files from one input file} @ref{File structure}.)

@seealso
Learning Manual:
@rlearning{Working on input files},
@rlearning{Music expressions explained},
@rlearning{Score is a (single) compound musical expression}.


@node Multiple scores in a book
@subsection Multiple scores in a book

@funindex \book
@cindex movements, multiple

A document may contain multiple pieces of music and text.  Examples
of these are an etude book, or an orchestral part with multiple
movements.  Each movement is entered with a @code{\score} block,

@example
\score @{
  @var{..music..}
@}
@end example

and texts are entered with a @code{\markup} block,

@example
\markup @{
  @var{..text..}
@}
@end example

@funindex \book

All the movements and texts which appear in the same @file{.ly} file
will normally be typeset in the form of a single output file.

@example
\score @{
  @var{..}
@}
\markup @{
  @var{..}
@}
\score @{
  @var{..}
@}
@end example

One important exception is within lilypond-book documents,
where you explicitly have to add a @code{\book} block, otherwise only
the first @code{\score} or @code{\markup} will appear in the output.

The header for each piece of music can be put inside the @code{\score}
block.  The @code{piece} name from the header will be printed before
each movement.  The title for the entire book can be put inside the
@code{\book}, but if it is not present, the @code{\header} which is at
the top of the file is inserted.

@example
\header @{
  title = "Eight miniatures"
  composer = "Igor Stravinsky"
@}
\score @{
  @dots{}
  \header @{ piece = "Romanze" @}
@}
\markup @{
   ..text of second verse..
@}
\markup @{
   ..text of third verse..
@}
\score @{
  @dots{}
  \header @{ piece = "Menuetto" @}
@}
@end example

@funindex \bookpart

Pieces of music may be grouped into book parts using @code{\bookpart}
blocks.  Book parts are separated by a page break, and can start with a
title, like the book itself, by specifying a @code{\header} block.

@example
\bookpart @{
  \header @{
    title = "Book title"
    subtitle = "First part"
  @}
  \score @{ @dots{} @}
  @dots{}
@}
\bookpart @{
  \header @{
    subtitle = "Second part"
  @}
  \score @{ @dots{} @}
  @dots{}
@}
@end example

@node Multiple output files from one input file
@subsection Multiple output files from one input file

If you want multiple output files from the same @file{.ly} file,
then you can add multiple @code{\book} blocks, where each
such \book block will result in a separate output file.
If you do not specify any @code{\book} block in the
input file, LilyPond will implicitly treat the whole
file as a single \book block, see
@ref{File structure}.

When producing multiple files from a single source file, Lilypond
ensures that none of the output files from any @code{\book} block
overwrites the output file produced by a preceding @code{\book} from
the same input file.

It does this by adding a suffix to the output name for each
@code{\book} which uses the default output file name derived from the
input source file.

The default behaviour is to append a version-number suffix for each
name which may clash, so

@example
\book @{
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
@end example

in source file @file{eightminiatures.ly}
will produce

@itemize
@item
@file{eightminiatures.pdf},
@item
@file{eightminiatures-1.pdf} and
@item
@file{eightminiatures-2.pdf}.
@end itemize

@node Output file names
@subsection Output file names

@funindex \bookOutputSuffix
@funindex \bookOutputName

Lilypond provides facilities to allow you to control what file names
are used by the various back-ends when producing output files.

In the previous section, we saw how Lilypond prevents name-clashes when
producing several ouputs from a single source file.  You also have the
ability to specify your own suffixes for each @code{\book} block, so
for example you can produce files called
@file{eightminiatures-Romanze.pdf}, @file{eightminiatures-Menuetto.pdf}
and @file{eightminiatures-Nocturne.pdf} by adding a
@code{\bookOutputSuffix} declaration inside each @code{\book} block.

@example
\book @{
  \bookOutputSuffix "Romanze"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \bookOutputSuffix "Menuetto"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \bookOutputSuffix "Nocturne"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
@end example

You can also specify a different output filename for @code{book} block,
by using @code{\bookOutputName} declarations

@example
\book @{
  \bookOutputName "Romanze"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \bookOutputName "Menuetto"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
\book @{
  \bookOutputName "Nocturne"
  \score @{ @dots{} @}
  \layout @{ @dots{} @}
@}
@end example

The file above will produce these output files:

@itemize
@item
@file{Romanze.pdf},
@item
@file{Menuetto.pdf} and
@item
@file{Nocturne.pdf}.
@end itemize


@node File structure
@subsection File structure

@funindex \paper
@funindex \midi
@funindex \layout
@funindex \header
@funindex \score
@funindex \book
@funindex \bookpart

A @file{.ly} file may contain any number of toplevel expressions, where a
toplevel expression is one of the following:

@itemize
@item
An output definition, such as @code{\paper}, @code{\midi}, and
@code{\layout}.  Such a definition at the toplevel changes the default
book-wide settings.  If more than one such definition of the same type
is entered at the top level the definitions are combined, but in
conflicting situations the later definitions take precedence.  For
details of how this affects the @code{\layout} block see
@ref{The \layout block}.

@item
A direct scheme expression, such as
@code{#(set-default-paper-size "a7" 'landscape)} or
@code{#(ly:set-option 'point-and-click #f)}.

@item
A @code{\header} block.  This sets the global header block.  This
is the block containing the definitions for book-wide settings, like
composer, title, etc.

@item
A @code{\score} block.  This score will be collected with other
toplevel scores, and combined as a single @code{\book}.
This behavior can be changed by setting the variable
@code{toplevel-score-handler} at toplevel.  The default handler is
defined in the init file @file{../scm/lily.scm}.

@item
A @code{\book} block logically combines multiple movements
(i.e., multiple @code{\score} blocks) in one document.  If there
are a number of @code{\score}s, one output file will be created
for each @code{\book} block, in which all corresponding movements
are concatenated.  The only reason to explicitly specify
@code{\book} blocks in a @file{.ly} file is if you wish to create
multiple output files from a single input file.  One exception is
within lilypond-book documents, where you explicitly have to add
a @code{\book} block if you want more than a single @code{\score}
or @code{\markup} in the same example.  This behavior can be
changed by setting the variable @code{toplevel-book-handler} at
toplevel.  The default handler is defined in the init file
@file{../scm/lily.scm}.

@item
A @code{\bookpart} block.  A book may be divided into several parts,
using @code{\bookpart} blocks, in order to ease the page breaking,
or to use different @code{\paper} settings in different parts.

@item
A compound music expression, such as
@example
@{ c'4 d' e'2 @}
@end example

This will add the piece in a @code{\score} and format it in a
single book together with all other toplevel @code{\score}s and music
expressions.  In other words, a file containing only the above
music expression will be translated into

@example
\book @{
  \score @{
    \new Staff @{
      \new Voice @{
        @{ c'4 d' e'2 @}
      @}
    @}
    \layout @{ @}
  @}
  \paper @{ @}
  \header @{ @}
@}
@end example

This behavior can be changed by setting the variable
@code{toplevel-music-handler} at toplevel.  The default handler is
defined in the init file @file{../scm/lily.scm}.

@item
A markup text, a verse for example
@example
\markup @{
   2.  The first line verse two.
@}
@end example

Markup texts are rendered above, between or below the scores or music
expressions, wherever they appear.

@cindex variables

@item
A variable, such as
@example
foo = @{ c4 d e d @}
@end example

This can be used later on in the file by entering @code{\foo}.  The
name of a variable should have alphabetic characters only; no
numbers, underscores or dashes.

@end itemize

The following example shows three things that may be entered at
toplevel

@example
\layout @{
  % Don't justify the output
  ragged-right = ##t
@}

\header @{
   title = "Do-re-mi"
@}

@{ c'4 d' e2 @}
@end example


At any point in a file, any of the following lexical instructions can
be entered:

@itemize
@item @code{\version}
@item @code{\include}
@item @code{\sourcefilename}
@item @code{\sourcefileline}
@item
A single-line comment, introduced by a leading @code{%} sign.

@item
A multi-line comment delimited by @code{%@{ .. %@}}.

@end itemize

@cindex whitespace

Whitespace between items in the input stream is generally ignored,
and may be freely omitted or extended to enhance readability.
However, whitespace should always be used in the following
circumstances to avoid errors:

@itemize
@item Around every opening and closing curly bracket.
@item After every command or variable, i.e. every item that
begins with a @code{\} sign.
@item After every item that is to be interpreted as a Scheme
expression, i.e. every item that begins with a @code{#}@tie{}sign.
@item To separate all elements of a Scheme expression.
@item In @code{lyricmode} to separate all the terms in both
@code{\override} and @code{\set} commands.  In particular, spaces
must be used around the dot and the equals sign in commands like
@code{\override Score . LyricText #'font-size = #5} and before and
after the entire command.

@end itemize

@seealso
Learning Manual:
@rlearning{How LilyPond input files work}.

Notation Reference:
@ref{The \layout block}.


@node Titles and headers
@section Titles and headers

Almost all printed music includes a title and the composer's name;
some pieces include a lot more information.

@menu
* Creating titles headers and footers::
* Custom headers footers and titles::
* Creating footnotes::
* Reference to page numbers::
* Table of contents::
@end menu


@node Creating titles headers and footers
@subsection Creating titles headers and footers

@menu
* Title blocks explained::
* Default layout of book and score title blocks::
* Default layout of headers and footers::
@end menu


@node Title blocks explained
@unnumberedsubsubsec Title blocks explained

@c TODO: figure out how \bookpart titles work

There are two types of title blocks: the main title block that appears
above of the first @code{\score} of a book, and individual title
blocks that appear within each @code{\score} block.  Text fields for
both types are entered using a @code{\header} block.

If the book only has a single score, the @code{\header} block may be
placed inside or outside of the @code{\score} block.

@warning{Remember when adding a @bs{}@code{header} block inside a
@bs{}@code{score} block, that the music expression must come before the
@bs{}@code{header} block.}

@lilypond[papersize=a5,quote,verbatim,noragged-right]
\header {
  title = "SUITE I."
  composer = "J. S. Bach."
}

\score {
  \new Staff \relative g, {
    \clef bass
    \key g \major
    \repeat unfold 2 { g16( d' b') a b d, b' d, } |
    \repeat unfold 2 { g,16( e' c') b c e, c' e, } |
  }
  \header {
    piece = "Prélude."
  }
}

\score {
  \new Staff \relative b {
    \clef bass
    \key g \major
    \partial 16 b16 |
    <g, d' b'~>4 b'16 a( g fis) g( d e fis) g( a b c) |
    d16( b g fis) g( e d c) b(c d e) fis( g a b) |
  }
  \header {
    piece = "Allemande."
  }
}
@end lilypond

Text fields from the main title block of a book can be displayed in all
@code{\score} blocks, or manually suppressed:

@lilypond[papersize=a5,quote,verbatim,noragged-right]
\book {
  \paper {
    print-all-headers = ##t
  }
  \header {
    title = "DAS WOHLTEMPERIRTE CLAVIER"
    subtitle = "TEIL I"
    % Do not display the tagline for this book
    tagline = ##f
  }
  \markup { \vspace #1 }
  \score {
    \new PianoStaff <<
      \new Staff { s1 }
      \new Staff { \clef "bass" s1 }
    >>
    \header {
      title = "PRAELUDIUM I"
      opus = "BWV 846"
      % Do not display the subtitle for this score
      subtitle = ##f
    }
  }
  \score {
    \new PianoStaff <<
      \new Staff { s1 }
      \new Staff { \clef "bass" s1 }
    >>
    \header {
      title = "FUGA I"
      subsubtitle = "A 4 VOCI"
      opus = "BWV 846"
      % Do not display the subtitle for this score
      subtitle = ##f
    }
  }
}
@end lilypond

@seealso
Notation Reference:
@ref{File structure},
@ref{Custom layout for title blocks}.


@node Default layout of book and score title blocks
@unnumberedsubsubsec Default layout of book and score title blocks

This example demonstrates all @code{\header} variables:

@lilypond[papersize=a7landscape,quote,verbatim,noragged-right]
\book {
  \header {
      % The following fields are centered
    dedication = "Dedication"
    title = "Title"
    subtitle = "Subtitle"
    subsubtitle = "Subsubtitle"
      % The following fields are evenly spread on one line
      % the field "instrument" also appears on following pages
    instrument = \markup \with-color #green "Instrument"
    poet = "Poet"
    composer = "Composer"
      % The following fields are placed at opposite ends of the same line
    meter = "Meter"
    arranger = "Arranger"
      % The following fields are centered at the bottom
    tagline = "tagline goes at the bottom of the last page"
    copyright = "copyright goes at the bottom of the first page"
  }
  \score {
    { s1 }
    \header {
        % The following fields are placed at opposite ends of the same line
      piece = "Piece 1"
      opus = "Opus 1"
    }
  }
  \score {
    { s1 }
    \header {
        % The following fields are placed at opposite ends of the same line
      piece = "Piece 2 on the same page"
      opus = "Opus 2"
    }
  }
  \pageBreak
  \score {
    { s1 }
    \header {
        % The following fields are placed at opposite ends of the same line
      piece = "Piece 3 on a new page"
      opus = "Opus 3"
    }
  }
}
@end lilypond

Note that

@itemize
@item
The instrument name will be repeated on every page.

@item
Only @code{piece} and @code{opus} are printed in a @code{\score}
when the paper variable @code{print-all-headers} is set to
@code{##f} (the default).

@item
@c Is the bit about \null markups true? -mp
Text fields left unset in a @code{\header} block are replaced with
@code{\null} markups so that the space is not wasted.

@item
The default settings for @code{scoreTitleMarkup} place the @code{piece}
and @code{opus} text fields at opposite ends of the same line.

@end itemize

To change the default layout see @ref{Custom layout for title blocks}.

@cindex breakbefore

Use the @code{breakbefore} variable inside a @code{\header} block
that is itself in a @code{\score} block, to make the top-level
@code{\header} block titles appear on the first page on their own, with
the music (defined in the @code{\score} block) starting on the next.

@lilypond[papersize=a8landscape,verbatim,noragged-right]
\book {
  \header {
    title = "This is my Title"
    subtitle = "This is my Subtitle"
    copyright = "This is the bottom of the first page"
  }
  \score {
    \repeat unfold 4 { e'' e'' e'' e'' }
    \header {
      piece = "This is the Music"
      breakbefore = ##t
    }
  }
}
@end lilypond

@seealso
Learning Manual:
@rlearning{How LilyPond input files work},

Notation Reference:
@ref{Custom layout for title blocks},
@ref{File structure}.

Installed Files:
@file{ly/titling-init.ly}.


@node Default layout of headers and footers
@unnumberedsubsubsec Default layout of headers and footers

@emph{Headers} and @emph{footers} are lines of text appearing at
the top and bottom of pages, separate from the main text of a book.
They are controlled by the following @code{\paper} variables:

@itemize
@item @code{oddHeaderMarkup}
@item @code{evenHeaderMarkup}
@item @code{oddFooterMarkup}
@item @code{evenFooterMarkup}
@end itemize

These markup variables can only access text fields from top-level
@code{\header} blocks (which apply to all scores in the book) and are
defined in @file{ly/titling-init.ly}.  By default:

@itemize

@item
page numbers are automatically placed on the top far left (if even) or
top far right (if odd), starting from the second page.

@item
the @code{instrument} text field is placed in the center of every
page, starting from the second page.

@item
the @code{copyright} text is centered on the bottom of the first page.

@item
the @code{tagline} is centered on the bottom of the last page, and below
the @code{copyright} text if there is only a single page.

@end itemize

@lilypond[papersize=a8landscape]
\book {
  \score {
    \relative c' {
      c4 d e f
    }
  }
}
@end lilypond

The default tagline can be changed by adding a @code{tagline} in the
top-level @code{\header} block.

@lilypond[papersize=a8landscape,verbatim]
\book {
  \header {
    tagline = "... music notation for Everyone"
  }
  \score {
    \relative c' {
      c4 d e f
    }
  }
}
@end lilypond

To remove the @code{tagline} set the value to @code{##f}.


@node Custom headers footers and titles
@subsection Custom headers footers and titles

@c TODO: somewhere put a link to header spacing info
@c       (you'll have to explain it more in NR 4).

@menu
* Custom text formatting for title blocks::
* Custom layout for title blocks::
* Custom layout for headers and footers::
@end menu


@node Custom text formatting for title blocks
@unnumberedsubsubsec Custom text formatting for title blocks

Standard @code{\markup} commands can be used to customize any header,
footer and title text within the @code{\header} block.

@lilypond[quote,verbatim,noragged-right]
\score {
  { s1 }
  \header {
    piece = \markup { \fontsize #4 \bold "PRAELUDIUM I" }
    subtitle = \markup { \italic "(Excerpt)" }
  }
}
@end lilypond

@seealso
Notation Reference:
@ref{Formatting text}.


@node Custom layout for title blocks
@unnumberedsubsubsec Custom layout for title blocks

@cindex bookTitleMarkup
@cindex scoreTitleMarkup
@funindex bookTitleMarkup
@funindex scoreTitleMarkup

@code{\markup} commands in the @code{\header} block are useful for
simple text formatting, but they do not allow precise control over the
placement of titles.  To customize the placement of the text fields,
change either or both of the following @code{\paper} variables:

@itemize
@item @code{bookTitleMarkup}
@item @code{scoreTitleMarkup}
@end itemize

The placement of titles when using the default values of these
@code{\markup} variables is shown in the examples in
@ref{Default layout of book and score title blocks}.

The default settings for @code{scoreTitleMarkup} as defined in
@file{ly/titling-init.ly} are:

@example
scoreTitleMarkup = \markup @{ \column @{
  \on-the-fly #print-all-headers @{ \bookTitleMarkup \hspace #1 @}
  \fill-line @{
    \fromproperty #'header:piece
    \fromproperty #'header:opus
  @}
@}
@}
@end example

This places the @code{piece} and @code{opus} text fields at opposite
ends of the same line:

@lilypond[quote,verbatim,noragged-right]
\score {
  { s1 }
  \header {
    piece = "PRAELUDIUM I"
    opus = "BWV 846"
  }
}
@end lilypond

This example redefines @code{scoreTitleMarkup} so that the @code{piece}
text field is centered and in a large, bold font.

@lilypond[papersize=a5,quote,verbatim,noragged-right]
\book {
  \paper {
    indent = 0\mm
    scoreTitleMarkup = \markup {
      \fill-line {
        \null
        \fontsize #4 \bold \fromproperty #'header:piece
        \fromproperty #'header:opus
      }
    }
  }
  \header { tagline = ##f }
  \score {
    { s1 }
    \header {
      piece = "PRAELUDIUM I"
      opus = "BWV 846"
    }
  }
}
@end lilypond

Text fields normally reserved for the main title block can be included
in individual score title blocks with the @code{print-all-headers}
placed inside the @code{\paper} block.  A disadvantage of using this
method is that the text fields that are intended specifically for the
top-level @code{\header} block need to be manually suppressed in every
@code{\score} block.  See @ref{Title blocks explained}.

To avoid this, add the desired text field to the @code{scoreTitleMarkup}
definition.  In the following example, the @code{composer} text field
(normally associated with @code{bookTitleMarkup}) is added to
@code{scoreTitleMarkup}, allowing each score to list a different
composer:

@lilypond[papersize=a5,quote,verbatim,noragged-right]
\book {
  \paper {
    indent = 0\mm
    scoreTitleMarkup = \markup {
      \fill-line {
        \null
        \fontsize #4 \bold \fromproperty #'header:piece
        \fromproperty #'header:composer
      }
    }
  }
  \header { tagline = ##f }
  \score {
    { s1 }
    \header {
      piece = "MENUET"
      composer = "Christian Petzold"
    }
  }
  \score {
    { s1 }
    \header {
      piece = "RONDEAU"
      composer = "François Couperin"
    }
  }
}
@end lilypond

It is also possible to create your own custom text fields, and refer to
them in the markup definition.

@lilypond[papersize=a5,quote,verbatim,noragged-right]
\book {
  \paper {
    indent = 0\mm
    scoreTitleMarkup = \markup {
      \fill-line {
        \null
        \override #`(direction . ,UP) {
          \dir-column {
            \center-align \fontsize #-1 \bold
              \fromproperty #'header:mycustomtext %% User-defined field
            \center-align \fontsize #4 \bold
              \fromproperty #'header:piece
          }
        }
        \fromproperty #'header:opus
      }
    }
  }
  \header { tagline = ##f }
  \score {
    { s1 }
    \header {
      piece = "FUGA I"
      mycustomtext = "A 4 VOCI" %% User-defined field
      opus = "BWV 846"
    }
  }
}
@end lilypond

@seealso
Notation Reference:
@ref{Title blocks explained}.


@node Custom layout for headers and footers
@unnumberedsubsubsec Custom layout for headers and footers

@c can make-header and make-footer be removed from
@c paper-defaults-init.ly? -mp

@code{\markup} commands in the @code{\header} block are useful for
simple text formatting, but they do not allow precise control over the
placement of headers and footers.  To customize the placement of
the text fields, use either or both of the following @code{\paper}
variables:

@itemize
@item @code{oddHeaderMarkup}
@item @code{evenHeaderMarkup}
@item @code{oddFooterMarkup}
@item @code{evenFooterMarkup}
@end itemize

@cindex markup, conditional
@cindex on-the-fly
@funindex \on-the-fly

The @code{\markup} command @code{\on-the-fly} can be used to add
markup conditionally to header and footer text defined within the
@code{\paper} block, using the following syntax:

@example
@code{variable} = @code{\markup} @{
  ...
  @code{\on-the-fly}  #@var{procedure}  @var{markup}
  ...
@}
@end example

The @var{procedure} is called each time the @code{\markup} command
in which it appears is evaluated.  The @var{procedure} should test
for a particular condition and interpret (i.e. print) the
@var{markup} argument if and only if the condition is true.

A number of ready-made procedures for testing various conditions are
provided:

@quotation
@multitable {print-page-number-check-first-----} {should this page be printed-----}

@headitem  Procedure name           @tab  Condition tested

@item print-page-number-check-first @tab  should this page number be printed?
@item create-page-number-stencil    @tab  'print-page-numbers true?
@item print-all-headers             @tab  'print-all-headers true?
@item first-page                    @tab  first page in the book?
@item (on-page nmbr)                @tab  page number = nmbr?
@item last-page                     @tab  last page in the book?
@item not-first-page                @tab  not first page in the book?
@item part-first-page               @tab  first page in the book part?
@item part-last-page                @tab  last page in the book part?
@item not-single-page               @tab  pages in book part > 1?

@end multitable
@end quotation

The following example centers page numbers at the bottom of every
page.  First, the default settings for @code{oddHeaderMarkup} and
@code{evenHeaderMarkup} are removed by defining each as a @emph{null}
markup.  Then, @code{oddFooterMarkup} is redefined with the page
number centered.  Finally, @code{evenFooterMarkup} is given the
same layout by defining it as @code{\oddFooterMarkup}:

@lilypond[papersize=a8,quote,verbatim,noragged-right]
\book {
  \paper {
    print-page-number = ##t
    print-first-page-number = ##t
    oddHeaderMarkup = \markup \null
    evenHeaderMarkup = \markup \null
    oddFooterMarkup = \markup {
      \fill-line {
        \on-the-fly #print-page-number-check-first
        \fromproperty #'page:page-number-string
      }
    }
    evenFooterMarkup = \oddFooterMarkup
  }
  \score {
    \new Staff { s1 \break s1 \break s1 }
  }
}
@end lilypond

Several @code{\on-the-fly} conditions can be combined with an
@q{and} operation, for example,

@example
  @code{\on-the-fly #first-page}
  @code{\on-the-fly #last-page}
  @code{@{ \markup ... \fromproperty #'header: ... @}}
@end example

determines if the output is a single page.

@seealso
Notation Reference:
@ref{Title blocks explained},
@ref{Default layout of book and score title blocks}.

Installed Files:
@file{../ly/titling-init.ly}.


@node Creating footnotes
@subsection Creating footnotes

There are two types of footnotes that can be created; automatic
footnotes and manual footnotes.

@menu
* Footnotes overview::
* Automatic footnotes::
* Manual footnotes::
@end menu

@node Footnotes overview
@unnumberedsubsubsec Footnotes overview

Automatic footnotes create incrementing numerical indicators and manual
footnotes allow a custom indicator to be created instead.  Footnotes are
normally applied like @code{\tweak} and consequently can be placed
directly on grobs (graphical objects) created by most music elements and
post-events.  In cases where this does not work (like with bar lines and
meter changes, where the grobs are produced as a consequence of property
changes), footnotes can also be specified as a standalone music event
affecting all grobs of a given type at a particular time step.

The full form of a footnote command is

@example
\footnote @var{mark} @var{offset} @var{grob-name} @var{footnote}
@var{music}
@end example

The elements are as follows:

@table @var
@item mark
is a markup or string specifying the footnote mark which is used for
both marking the reference point as well as the footnote itself at the
bottom of the page.  It can be omitted (or equivalently replaced with
@code{\default}) in which case a number in sequence will be generated.
@item offset
is a number pair such as @samp{#(2 . 1)} specifying the X and Y offset
from the reference point where the mark will be placed.
@item grob-name
specifies a type of grob to mark (like @samp{#'Flag}).  If it is given,
the respective grob will be used as a reference point even in case that
its @q{cause} is not the referenced @var{music} itself but a grob
created from it.  It can be omitted (or replaced with @code{\default}),
and then only a directly created grob will be annotated.
@item footnote
This markup or string specifies the footnote text to use at the bottom
of the page.
@item music
This is the item, a music event or chord constituent or post-event, that
is being annotated.  While it cannot be omitted, it @emph{can} be
replaced by @code{\default} in which case the footnote is not attached
to a music expression in particular, but rather to a moment of time.  It
is mandatory in this case to use the @var{grob-name} argument for
selecting an affected grob type, like @samp{#'TimeSignature}.
@end table

Like with @code{\tweak}, if your @code{\footnote} is applied to a
post-event or articulation, it will itself have to be preceded with
@code{-} to make the parser attach the result to the preceding note or
rest.

@node Automatic footnotes
@unnumberedsubsubsec Automatic footnotes

Automatic footnotes take four arguments: the @samp{(x . y)} position of
the indicator, the optional @var{grob-name} specifying the layout object
to be annotated, the @var{footnote} markup itself that will appear at
the bottom of the page, and of course the @var{music} to attach the
footnote to.

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \relative c' {
    \footnote #'(0.5 . -2)
      \markup { The first note }
    a'4 b8
    \footnote #'(0.5 . 1) #'Flag
      \markup { The third note }
    e\noBeam c4 d4
  }
}
@end lilypond

Chorded notes pose no particular difficulty:

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \relative c' {
    <
    \footnote #'(1 . -1.25) "Here is a C" c
    \footnote #'(2 . -0.25) \markup { \italic "An E-flat" } es
    \footnote #'(2 . 3) \markup { \bold "This is a G" } g
    >1
  }
}
@end lilypond

@warning {When footnotes have the same vertical position, the footnotes
are printed in order of descendancy; the higher the footnote, the
higher up in the list.}

Here are some more examples of footnoted grobs, also showing the
relative position of the footnotes to the tagline and copyright.

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { copyright = \markup { "Copyright 1970" } }
  \relative c' {
    a'4-\footnote #'(-3 . 0) \markup { \bold Forte } \f
    -\footnote #'(0 . 1.5) \markup { A slur } (
    b8)-\footnote #'(0 . -2) \markup { Beam } [ e]
    \footnote #'(1 . -1) #'Stem
      \markup  { \teeny { This is a stem } }
    c4
    \footnote #'(0 . 0.5) #'AccidentalCautionary
      \markup \italic { A cautionary accidental }
    \footnote #'(1 . 1) "The note itself"
    dis?4-\footnote #'(0.5 . -0.5) \markup \italic { Slow Down }
         _"rit."
  }
}
@end lilypond

For top-level @code{\markup}, the @code{\auto-footnote} command is
required:

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \markup { \auto-footnote "A simple tune" \italic "By me" }
  \relative c' {
    a'4 b8 e c4 d
  }
}
@end lilypond


@node Manual footnotes
@unnumberedsubsubsec Manual footnotes

@cindex footnotes, manual

Manually marked footnotes take an additional first markup argument
@var{mark} for making the reference mark.  In contrast to automatically
generated footnote marks, they will not appear before the @var{footnote}
markup at the bottom of the page: establishing the visual connection is
left to the user.  LilyPond will only make sure that the corresponding
markup appears on the bottom of the same page.

Other than that, the use is identical to that of automatically numbered
footnotes.

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \relative c' {
    \footnote
          "1" #'(0.5 . -2)
          \markup { \italic "1. The first note" }
    a'4
    b8
    \footnote
          \markup { \bold "2" } #'(0.5 . 1)
          "2. The second note"
    e
    c4
    d-\footnote "3" #'(0.5 . -1) "3. Piano" \p
  }
}
@end lilypond

To annotate chorded notes with manual footnotes:

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \relative c' {
    <
    \footnote "1" #'(1 . -1.25) "1. C" c
    \footnote
       \markup { \bold "b" } #'(2 . -0.25) "b. E-flat" es
    \footnote "3" #'(2 . 3) \markup { \italic "iii. G" } g
    >1
  }
}
@end lilypond

@warning {When footnotes have the same vertical position, the footnotes
are printed in order of descendancy; the higher the footnote, the
higher up in the list.}

Here are some examples of manually footnoted grobs, also showing
the relative position of the footnotes to the tagline and copyright

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \relative c' {
    a'4-\footnote
      \markup { \teeny 1 } #'(-3 . 0)
      \markup { 1. \bold Forte } \f
    -\footnote
      \markup { \teeny b } #'(0 . 1.5)
      \markup { b. A slur } (
    b8)-\footnote
      \markup { \teeny 3 } #'(0 . -2)
      \markup { 3. Beam } [
    e]
    \footnote
      \markup { 4 } #'(1 . -1) #'Stem
      \markup  { \bold 4. { This is a stem } }
    c4
    \footnote
      \markup \concat \teeny { "sharp (v)" }
          #'(0 . 0.5) #'AccidentalCautionary
      \markup \italic { v. A cautionary accidental }
    dis?4-\footnote
      \markup \concat \teeny { "a" } #'(0.5 . -0.5)
      \markup \italic { a. Slow Down } _"rit."
    \footnote
      \markup { \teeny \musicglyph #"rests.4" }
          #'(1.5 . -0.25)
      \markup { \null } \breathe
  }
}
@end lilypond

To manually footnote a top-level @code{\markup}:

@lilypond[verbatim,quote,ragged-right,papersize=a8]
\book {
  \header { tagline = ##f }
  \markup { "A simple tune" \footnote "*" \italic "* By me" }
  \relative c' {
    a'4 b8 e c4 d4
  }
}
@end lilypond

@seealso
Learning Manual:
@rlearning{Objects and interfaces}.

Notation Reference:
@ref{Balloon help},
@ref{Page layout},
@ref{Text marks},
@ref{Text scripts},
@ref{Titles and headers}.

Internals Reference:
@rinternals{FootnoteEvent},
@rinternals{FootnoteItem},
@rinternals{FootnoteSpanner},
@rinternals{Footnote_engraver}.

@knownissues
Multiple footnotes for the same page can only be stacked, one on top of
the other, and cannot be printed on the same line.  Footnotes cannot be
attached to @code{MultiMeasureRests} and may collide with @code{Staff},
@code{\markup} objects and other @code{footnote} annotations.  When
using any manual @code{footnote} command a @code{\paper} block
containing @code{footnote-auto-number = ##f} is required.


@node Reference to page numbers
@subsection Reference to page numbers

A particular place of a score can be marked using the @code{\label}
command, either at top-level or inside music.  This label can then be
referred to in a markup, to get the number of the page where the marked
point is placed, using the @code{\page-ref} markup command.

@lilypond[verbatim,papersize=a8landscape]
\header { tagline = ##f }
\book {
  \label #'firstScore
  \score {
    {
      c'1
      \pageBreak \mark A \label #'markA
      c'1
    }
  }
  \markup { The first score begins on page \page-ref #'firstScore "0" "?" }
  \markup { Mark A is on page \page-ref #'markA "0" "?" }
}
@end lilypond

The @code{\page-ref} markup command takes three arguments:
@enumerate
@item the label, a scheme symbol, eg. @code{#'firstScore};
@item a markup that will be used as a gauge to estimate the dimensions
of the markup;
@item a markup that will be used in place of the page number if the label
is not known;
@end enumerate

The reason why a gauge is needed is that, at the time markups are
interpreted, the page breaking has not yet occurred, so the page numbers
are not yet known.  To work around this issue, the actual markup
interpretation is delayed to a later time; however, the dimensions of
the markup have to be known before, so a gauge is used to decide these
dimensions.  If the book has between 10 and 99 pages, it may be "00",
ie. a two digit number.


@predefined
@funindex \label
@code{\label},
@funindex \page-ref
@code{\page-ref}.
@endpredefined


@node Table of contents
@subsection Table of contents
A table of contents is included using the @code{\markuplist \table-of-contents}
command.  The elements which should appear in the table of contents are
entered with the @code{\tocItem} command, which may be used either at
top-level, or inside a music expression.

@verbatim
\markuplist \table-of-contents
\pageBreak

\tocItem \markup "First score"
\score {
  {
    c'4  % ...
    \tocItem \markup "Some particular point in the first score"
    d'4  % ...
  }
}

\tocItem \markup "Second score"
\score {
  {
    e'4 % ...
  }
}
@end verbatim

The markups which are used to format the table of contents are defined
in the @code{\paper} block.  The default ones are @code{tocTitleMarkup},
for formatting the title of the table, and @code{tocItemMarkup}, for
formatting the toc elements, composed of the element title and page
number.  These variables may be changed by the user:

@verbatim
\paper {
  %% Translate the toc title into French:
  tocTitleMarkup = \markup \huge \column {
    \fill-line { \null "Table des matières" \null }
    \hspace #1
  }
  %% use larger font size
  tocItemMarkup = \markup \large \fill-line {
    \fromproperty #'toc:text \fromproperty #'toc:page
  }
}
@end verbatim

Note how the toc element text and page number are referred to in
the @code{tocItemMarkup} definition.

New commands and markups may also be defined to build more elaborated
table of contents:
@itemize
@item first, define a new markup variable in the @code{\paper} block
@item then, define a music function which aims at adding a toc element
using this markup paper variable.
@end itemize

In the following example, a new style is defined for entering act names
in the table of contents of an opera:

@verbatim
\paper {
  tocActMarkup = \markup \large \column {
    \hspace #1
    \fill-line { \null \italic \fromproperty #'toc:text \null }
    \hspace #1
  }
}

tocAct =
#(define-music-function (parser location text) (markup?)
   (add-toc-item! 'tocActMarkup text))
@end verbatim

@lilypond[line-width=10.0\cm]
\header { tagline = ##f }
\paper {
  tocActMarkup = \markup \large \column {
    \hspace #1
    \fill-line { \null \italic \fromproperty #'toc:text \null }
    \hspace #1
  }
}

tocAct =
#(define-music-function (parser location text) (markup?)
   (add-toc-item! 'tocActMarkup text))

\book {
  \markuplist \table-of-contents
  \tocAct \markup { Atto Primo }
  \tocItem \markup { Coro. Viva il nostro Alcide }
  \tocItem \markup { Cesare. Presti omai l'Egizzia terra }
  \tocAct \markup { Atto Secondo }
  \tocItem \markup { Sinfonia }
  \tocItem \markup { Cleopatra. V'adoro, pupille, saette d'Amore }
  \markup \null
}
@end lilypond

Dots can be added to fill the line between an item and its page number:

@lilypond[verbatim,line-width=10.0\cm]
\header { tagline = ##f }
\paper {
  tocItemMarkup = \tocItemWithDotsMarkup
}

\book {
  \markuplist \table-of-contents
  \tocItem \markup { Allegro }
  \tocItem \markup { Largo }
  \markup \null
}
@end lilypond

@seealso
Installed Files:
@file{ly/toc-init.ly}.

@predefined
@funindex \table-of-contents
@code{\table-of-contents},
@funindex \tocItem
@code{\tocItem}.
@endpredefined


@node Working with input files
@section Working with input files

@menu
* Including LilyPond files::
* Different editions from one source::
* Special characters::
@end menu


@node Including LilyPond files
@subsection Including LilyPond files

@funindex \include
@cindex including files

A large project may be split up into separate files.  To refer to
another file, use

@example
\include "otherfile.ly"
@end example

The line @code{\include "otherfile.ly"} is equivalent to pasting the
contents of @file{otherfile.ly} into the current file at the place
where the @code{\include} appears.  For example, in a large
project you might write separate files for each instrument part
and create a @qq{full score} file which brings together the
individual instrument files.  Normally the included file will
define a number of variables which then become available
for use in the full score file.  Tagged sections can be
marked in included files to assist in making them usable in
different places in a score, see @ref{Different editions from
one source}.

Files in the current working directory may be referenced by
specifying just the file name after the @code{\include} command.
Files in other locations may be included by giving either a full
path reference or a relative path reference (but use the UNIX
forward slash, /, rather than the DOS/Windows back slash, \, as the
directory separator.)  For example, if @file{stuff.ly} is located
one directory higher than the current working directory, use

@example
\include "../stuff.ly"
@end example

@noindent
or if the included orchestral parts files are all located in a
subdirectory called @file{parts} within the current directory, use

@example
\include "parts/VI.ly"
\include "parts/VII.ly"
... etc
@end example

Files which are to be included can also contain @code{\include}
statements of their own.  By default, these second-level
@code{\include} statements are not interpreted until they have
been brought into the main file, so the file names they specify
must all be relative to the directory containing the main file,
not the directory containing the included file.  However,
this behavior can be changed by passing the option
@option{-drelative-includes} option at the command line
(or by adding @code{#(ly:set-option 'relative-includes #t)}
at the top of the main input file).  With @code{relative-includes}
set, the path for each @code{\include} command will be taken
relative to the file containing that command.  This behavior is
recommended and it will become the default behavior in a future
version of lilypond.

Files can also be included from a directory in a search path
specified as an option when invoking LilyPond from the command
line.  The included files are then specified using just their
file name.  For example, to compile @file{main.ly} which includes
files located in a subdirectory called @file{parts} by this method,
cd to the directory containing @file{main.ly} and enter

@example
lilypond --include=parts main.ly
@end example

and in main.ly write

@example
\include "VI.ly"
\include "VII.ly"
... etc
@end example

Files which are to be included in many scores may be placed in
the LilyPond directory @file{../ly}.  (The location of this
directory is installation-dependent - see
@rlearning{Other sources of information}).  These files can then
be included simply by naming them on an @code{\include} statement.
This is how the language-dependent files like @file{english.ly} are
included.

LilyPond includes a number of files by default when you start
the program.  These includes are not apparent to the user, but the
files may be identified by running @code{lilypond --verbose} from
the command line.  This will display a list of paths and files that
LilyPond uses, along with much other information.  Alternatively,
the more important of these files are discussed in
@rlearning{Other sources of information}.  These files may be
edited, but changes to them will be lost on installing a new
version of LilyPond.

Some simple examples of using @code{\include} are shown in
@rlearning{Scores and parts}.

@seealso
Learning Manual:
@rlearning{Other sources of information},
@rlearning{Scores and parts}.

@knownissues
If an included file is given a name which is the same as one in
LilyPond's installation files, LilyPond's file from the
installation files takes precedence.


@node Different editions from one source
@subsection Different editions from one source

Several methods can be used to generate different versions of a score
from the same music source.  Variables are perhaps the most useful for
combining lengthy sections of music and/or annotation.  Tags are more
useful for selecting one section from several alternative shorter
sections of music, and can also be used for splicing pieces of music
together at different points.

Whichever method is used, separating the notation from the structure of
the score will make it easier to change the structure while leaving the
notation untouched.

@menu
* Using variables::
* Using tags::
* Using global settings::
@end menu

@node Using variables
@unnumberedsubsubsec Using variables

@cindex variables, use of

If sections of the music are defined in variables they can be
reused in different parts of the score, see @rlearning{Organizing
pieces with variables}.  For example, an @notation{a cappella}
vocal score frequently includes a piano reduction of the parts
for rehearsal purposes which is identical to the vocal music, so
the music need be entered only once.  Music from two variables
may be combined on one staff, see @ref{Automatic part combining}.
Here is an example:

@lilypond[verbatim,quote]
sopranoMusic = \relative c'' { a4 b c b8( a) }
altoMusic = \relative g' { e4 e e f }
tenorMusic = \relative c' { c4 b e d8( c) }
bassMusic = \relative c' { a4 gis a d, }
allLyrics = \lyricmode {King of glo -- ry }
<<
  \new Staff = "Soprano" \sopranoMusic
  \new Lyrics \allLyrics
  \new Staff = "Alto" \altoMusic
  \new Lyrics \allLyrics
  \new Staff = "Tenor" {
    \clef "treble_8"
    \tenorMusic
  }
  \new Lyrics \allLyrics
  \new Staff = "Bass" {
    \clef "bass"
    \bassMusic
  }
  \new Lyrics \allLyrics
  \new PianoStaff <<
    \new Staff = "RH" {
      \set Staff.printPartCombineTexts = ##f
      \partcombine
      \sopranoMusic
      \altoMusic
    }
    \new Staff = "LH" {
      \set Staff.printPartCombineTexts = ##f
      \clef "bass"
      \partcombine
      \tenorMusic
      \bassMusic
    }
  >>
>>
@end lilypond

Separate scores showing just the vocal parts or just the piano
part can be produced by changing just the structural statements,
leaving the musical notation unchanged.

For lengthy scores, the variable definitions may be placed in
separate files which are then included, see @ref{Including
LilyPond files}.

@node Using tags
@unnumberedsubsubsec Using tags

@funindex \tag
@funindex \keepWithTag
@funindex \removeWithTag
@funindex \pushToTag
@funindex \appendToTag
@cindex tag
@cindex keep tagged music
@cindex remove tagged music
@cindex splice into tagged music

The @code{\tag #'@var{partA}} command marks a music expression
with the name @var{partA}.
Expressions tagged in this way can be selected or filtered out by
name later, using either @code{\keepWithTag #'@var{name}} or
@code{\removeWithTag #'@var{name}}.  The result of applying these filters
to tagged music is as follows:
@multitable @columnfractions .5 .5
@headitem Filter
  @tab Result
@item
Tagged music preceded by @code{\keepWithTag #'@var{name}}
  @tab Untagged music and music tagged with @var{name} is included;
       music tagged with any other tag name is excluded.
@item
Tagged music preceded by @code{\removeWithTag #'@var{name}}
@tab Untagged music and music tagged with any tag name other than
     @var{name} is included; music tagged with @var{name} is
     excluded.
@item
Tagged music not preceded by either @code{\keepWithTag} or
@code{\removeWithTag}
@tab All tagged and untagged music is included.
@end multitable

The arguments of the @code{\tag}, @code{\keepWithTag} and
@code{\removeWithTag} commands should be a symbol
(such as @code{#'score} or @code{#'part}), followed
by a music expression.

In the following example, we see two versions of a piece of music,
one showing trills with the usual notation, and one with trills
explicitly expanded:

@lilypond[verbatim,quote]
music = \relative g' {
  g8. c32 d
  \tag #'trills { d8.\trill }
  \tag #'expand { \repeat unfold 3 { e32 d } }
  c32 d
 }

\score {
  \keepWithTag #'trills \music
}
\score {
  \keepWithTag #'expand \music
}
@end lilypond

@noindent
Alternatively, it is sometimes easier to exclude sections of music:

@lilypond[verbatim,quote]
music = \relative g' {
  g8. c32 d
  \tag #'trills { d8.\trill }
  \tag #'expand {\repeat unfold 3 { e32 d } }
  c32 d
 }

\score {
  \removeWithTag #'expand
  \music
}
\score {
  \removeWithTag #'trills
  \music
}
@end lilypond

Tagged filtering can be applied to articulations, texts, etc. by
prepending

@example
-\tag #'@var{your-tag}
@end example

to an articulation.  For example, this would define a note with a
conditional fingering indication and a note with a conditional
annotation:

@example
c1-\tag #'finger ^4
c1-\tag #'warn ^"Watch!"
@end example

Multiple tags may be placed on expressions with multiple
@code{\tag} entries:

@lilypond[quote,verbatim]
music = \relative c'' {
  \tag #'a \tag #'both { a4 a a a }
  \tag #'b \tag #'both { b4 b b b }
}
<<
\keepWithTag #'a \music
\keepWithTag #'b \music
\keepWithTag #'both \music
>>
@end lilypond

Multiple @code{\removeWithTag} filters may be applied to a single
music expression to remove several differently named tagged sections:

@lilypond[verbatim,quote]
music = \relative c'' {
\tag #'A { a4 a a a }
\tag #'B { b4 b b b }
\tag #'C { c4 c c c }
\tag #'D { d4 d d d }
}
{
\removeWithTag #'B
\removeWithTag #'C
\music
}
@end lilypond

Two or more @code{\keepWithTag} filters applied to a single music
expression will cause @emph{all} tagged sections to be removed, as
the first filter will remove all tagged sections except the one
named, and the second filter will remove even that tagged section.

Sometimes you want to splice some music at a particular place in an
existing music expression.  You can use @code{\pushToTag} and
@code{\appendToTag} for adding material at the front or end of the
@code{elements} of an existing music construct.  Not every music
construct has @code{elements}, but sequential and simultaneous music are
safe bets:

@lilypond[verbatim,quote]
test = { \tag #'here { \tag #'here <<c''>> } }

{
  \pushToTag #'here c'
  \pushToTag #'here e'
  \pushToTag #'here g' \test
  \appendToTag #'here c'
  \appendToTag #'here e'
  \appendToTag #'here g' \test
}
@end lilypond

Both commands get a tag, the material to splice in at every occurence of
the tag, and the tagged expression.  The commands make sure to
copy everything that they change so that the original @code{\test}
retains its meaning.

@seealso
Learning Manual:
@rlearning{Organizing pieces with variables}.

Notation Reference:
@ref{Automatic part combining},
@ref{Including LilyPond files}.

@ignore
@c This warning is more general than this placement implies.
@c Rests are not merged whether or not they come from tagged sections.
@c Should be deleted?  -td

@knownissues
Multiple rests are not merged if you create a score with more
than one tagged section at the same place.

@end ignore


@node Using global settings
@unnumberedsubsubsec Using global settings

@cindex include-settings

Global settings can be included from a separate file:

@example
lilypond -dinclude-settings=MY_SETTINGS.ly MY_SCORE.ly
@end example

Groups of settings such as page size, font or type face can be stored
in separate files. This allows different editions from the same score
as well as standard settings to be applied to many scores, simply by
specifying the proper settings file.

This technique also works well with the use of style sheets, as
discussed in @rlearning{Style sheets}.

@seealso
Learning Manual:
@rlearning{Organizing pieces with variables},
@rlearning{Style sheets}.

Notation Reference:
@ref{Including LilyPond files}.


@node Special characters
@subsection Special characters

@cindex special characters
@cindex non-ASCII characters

@menu
* Text encoding::
* Unicode::
* ASCII aliases::
@end menu


@node Text encoding
@unnumberedsubsubsec Text encoding

@cindex UTF-8

LilyPond uses the character repertoire defined by the Unicode
consortium and ISO/IEC 10646.  This defines a unique name and
code point for the character sets used in virtually all modern
languages and many others too.  Unicode can be implemented using
several different encodings.  LilyPond uses the UTF-8 encoding
(UTF stands for Unicode Transformation Format) which represents
all common Latin characters in one byte, and represents other
characters using a variable length format of up to four bytes.

The actual appearance of the characters is determined by the
glyphs defined in the particular fonts available - a font defines
the mapping of a subset of the Unicode code points to glyphs.
LilyPond uses the Pango library to layout and render multi-lingual
texts.

LilyPond does not perform any input-encoding conversions.  This
means that any text, be it title, lyric text, or musical
instruction containing non-ASCII characters, must be encoded in
UTF-8.  The easiest way to enter such text is by using a
Unicode-aware editor and saving the file with UTF-8 encoding.  Most
popular modern editors have UTF-8 support, for example, vim, Emacs,
jEdit, and GEdit do.  All MS Windows systems later than NT use
Unicode as their native character encoding, so even Notepad can
edit and save a file in UTF-8 format.  A more functional
alternative for Windows is BabelPad.

If a LilyPond input file containing a non-ASCII character is not
saved in UTF-8 format the error message

@example
FT_Get_Glyph_Name () error: invalid argument
@end example

will be generated.

Here is an example showing Cyrillic, Hebrew and Portuguese
text:

@lilypond[quote]
%c No verbatim here as the code does not display correctly in PDF
% Cyrillic
bulgarian = \lyricmode {
  Жълтата дюля беше щастлива, че пухът, който цъфна, замръзна като гьон.
}

% Hebrew
hebrew = \lyricmode {
  זה כיף סתם לשמוע איך תנצח קרפד עץ טוב בגן.
}

% Portuguese
portuguese = \lyricmode {
  à vo -- cê uma can -- ção legal
}

\relative c' {
  c2 d e f g f e
}
\addlyrics { \bulgarian }
\addlyrics { \hebrew }
\addlyrics { \portuguese }
@end lilypond


@node Unicode
@unnumberedsubsubsec Unicode

@cindex Unicode

To enter a single character for which the Unicode code point is
known but which is not available in the editor being used, use
either @code{\char ##xhhhh} or @code{\char #dddd} within a
@code{\markup} block, where @code{hhhh} is the hexadecimal code for
the character required and @code{dddd} is the corresponding decimal
value.  Leading zeroes may be omitted, but it is usual to specify
all four characters in the hexadecimal representation.  (Note that
the UTF-8 encoding of the code point should @emph{not} be used
after @code{\char}, as UTF-8 encodings contain extra bits indicating
the number of octets.)  Unicode code charts and a character name
index giving the code point in hexadecimal for any character can be
found on the Unicode Consortium website,
@uref{http://www.unicode.org/}.

For example, @code{\char ##x03BE} and @code{\char #958} would both
enter the Unicode U+03BE character, which has the Unicode name
@qq{Greek Small Letter Xi}.

Any Unicode code point may be entered in this way and if all special
characters are entered in this format it is not necessary to save
the input file in UTF-8 format.  Of course, a font containing all
such encoded characters must be installed and available to LilyPond.

The following example shows Unicode hexadecimal values being entered
in four places -- in a rehearsal mark, as articulation text, in
lyrics and as stand-alone text below the score:

@lilypond[quote,verbatim]
\score {
  \relative c'' {
    c1 \mark \markup { \char ##x03EE }
    c1_\markup { \tiny { \char ##x03B1 " to " \char ##x03C9 } }
  }
  \addlyrics { O \markup { \concat { Ph \char ##x0153 be! } } }
}
\markup { "Copyright 2008--2012" \char ##x00A9 }
@end lilypond

@cindex copyright sign

To enter the copyright sign in the copyright notice use:

@example
\header @{
  copyright = \markup @{ \char ##x00A9 "2008" @}
@}
@end example


@node ASCII aliases
@unnumberedsubsubsec ASCII aliases

A list of ASCII aliases for special characters can be included:

@lilypond[quote,verbatim]
\paper {
  #(include-special-characters)
}

\markup "&flqq; &ndash; &OE;uvre incomplète&hellip; &frqq;"

\score {
  \new Staff { \repeat unfold 9 a'4 }
  \addlyrics {
    This is al -- so wor -- kin'~in ly -- rics: &ndash;_&OE;&hellip;
  }
}

\markup \column {
  "The replacement can be disabled:"
  "&ndash; &OE; &hellip;"
  \override #'(replacement-alist . ()) "&ndash; &OE; &hellip;"
}
@end lilypond

You can also make your own aliases, either globally:

@lilypond[quote,verbatim]
\paper {
  #(add-text-replacements!
    '(("100" . "hundred")
      ("dpi" . "dots per inch")))
}
\markup "A 100 dpi."
@end lilypond

or locally:

@lilypond[quote,verbatim]
\markup \replace #'(("100" . "hundred")
                    ("dpi" . "dots per inch")) "A 100 dpi."
@end lilypond

@seealso
Notation Reference:
@ref{List of special characters}.

Installed Files:
@file{ly/text-replacements.ly}.


@node Controlling output
@section Controlling output

@menu
* Extracting fragments of music::
* Skipping corrected music::
* Alternative output formats::
* Replacing the notation font::
@end menu

@node Extracting fragments of music
@subsection Extracting fragments of music

It is possible to quote small fragments of a large score directly from
the output.  This can be compared to clipping a piece of a paper score
with scissors.

This is done by defining the measures that need to be cut out
separately.  For example, including the following definition


@verbatim
\layout {
  clip-regions
  = #(list
      (cons
       (make-rhythmic-location 5 1 2)
       (make-rhythmic-location 7 3 4)))
}
@end verbatim

@noindent
will extract a fragment starting halfway the fifth measure, ending in
the seventh measure.  The meaning of @code{5 1 2} is: after a 1/2 note
in measure 5, and @code{7 3 4} after 3 quarter notes in measure 7.

More clip regions can be defined by adding more pairs of
rhythmic-locations to the list.

In order to use this feature, LilyPond must be invoked with
@option{-dclip-systems}.  The clips are output as EPS files, and are
converted to PDF and PNG if these formats are switched on as well.

For more information on output formats, see @rprogram{Invoking lilypond}.

@node Skipping corrected music
@subsection Skipping corrected music


@funindex skipTypesetting
@funindex showFirstLength
@funindex showLastLength

When entering or copying music, usually only the music near the end (where
you
are adding notes) is interesting to view and correct.  To speed up
this correction process, it is possible to skip typesetting of all but
the last few measures.  This is achieved by putting

@verbatim
showLastLength = R1*5
\score { ... }
@end verbatim

@noindent
in your source file.  This will render only the last 5 measures
(assuming 4/4 time signature) of every @code{\score} in the input
file.  For longer pieces, rendering only a small part is often an order
of magnitude quicker than rendering it completely.  When working on the
beginning of a score you have already typeset (e.g. to add a new part),
the @code{showFirstLength} property may be useful as well.

Skipping parts of a score can be controlled in a more fine-grained
fashion with the property @code{Score.skipTypesetting}.  When it is
set, no typesetting is performed at all.

This property is also used to control output to the MIDI file.  Note that
it skips all events, including tempo and instrument changes.  You have
been warned.

@lilypond[quote,relative=2,ragged-right,verbatim]
c8 d
\set Score.skipTypesetting = ##t
e8 e e e e e e e
\set Score.skipTypesetting = ##f
c8 d b bes a g c2
@end lilypond

In polyphonic music, @code{Score.skipTypesetting} will affect all
voices and staves, saving even more time.

@node Alternative output formats
@subsection Alternative output formats

@cindex scalable vector graphics output
@cindex SVG output
@cindex encapsulated postscript output
@cindex EPS output

The default output formats for the printed score are Portable
Document Format (PDF) and PostScript (PS).  Scalable Vector
Graphics (SVG), Encapsulated PostScript (EPS) and Portable
Network Graphics (PNG) output formats are also available through
command line options, see
@rprogram{Basic command line options for LilyPond}.


@node Replacing the notation font
@subsection Replacing the notation font

Gonville is an alternative to the Feta font used in LilyPond and can
be downloaded from:
@example
@uref{http://www.chiark.greenend.org.uk/~sgtatham/gonville/ ,http://www.chiark.greenend.org.uk/~sgtatham/gonville/}
@end example

Here are a few sample bars of music set in Gonville:

@c NOTE: these images are a bit big, but that's important
@c       for the font comparison.  -gp
@sourceimage{Gonville_after,,,}

Here are a few sample bars of music set in LilyPond's Feta font:

@sourceimage{Gonville_before,,,}

@subsubheading Installation Instructions for MacOS

Download and extract the zip file.  Copy the @code{lilyfonts}
directory to @file{@var{SHARE_DIR}/lilypond/current}; for more
information, see @rlearning{Other sources of information}.  Rename the
existing @code{fonts} directory to @code{fonts_orig} and the
@code{lilyfonts} directory to @code{fonts}.  To revert back to Feta,
reverse the process.

@seealso
Learning Manual:
@rlearning{Other sources of information}.

@knownissues
Gonville cannot be used to typeset @q{Ancient Music} notation and it is
likely newer glyphs in later releases of LilyPond may not exist in the
Gonville font family.  Please refer to the author's website for more
information on these and other specifics, including licensing of
Gonville.


@node MIDI output
@section MIDI output

@cindex Sound
@cindex MIDI

MIDI (Musical Instrument Digital Interface) is a standard for
connecting and controlling digital instruments.  A MIDI file is a
series of notes in a number of tracks.  It is not an actual
sound file; you need special software to translate between the
series of notes and actual sounds.

Pieces of music can be converted to MIDI files, so you can listen to
what was entered.  This is convenient for checking the music; octaves
that are off or accidentals that were mistyped stand out very much
when listening to the MIDI output.

Standard MIDI output is somewhat crude; optionally, an enhanced and
more realistic MIDI output is available by means of
@ref{The Articulate script}.

The MIDI output allocates a channel for each staff, and reserves channel
10 for drums.  There are only 16 MIDI channels per device, so if the
score contains more than 15 staves, MIDI channels will be reused.

@menu
* Creating MIDI files::
* MIDI block::
* What goes into the MIDI output?::
* Repeats in MIDI::
* Controlling MIDI dynamics::
* Percussion in MIDI::
* The Articulate script::
@end menu

@node Creating MIDI files
@subsection Creating MIDI files

To create a MIDI output file from a LilyPond input file, add a
@code{\midi} block to a score, for example,

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

If there is a @code{\midi} block in a @code{\score} with no
@code{\layout} block, only MIDI output will be produced.  When
notation is needed too, a @code{\layout} block must also be
present.

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

Pitches, rhythms, ties, dynamics, and tempo changes are interpreted
and translated correctly to the MIDI output.  Dynamic marks,
crescendi and decrescendi translate into MIDI volume levels.
Dynamic marks translate to a fixed fraction of the available MIDI
volume range.  Crescendi and decrescendi make the volume vary
linearly between their two extremes.  The effect of dynamic markings
on the MIDI output can be removed completely, see @ref{MIDI block}.

The initial tempo and later tempo changes can be specified
with the @code{\tempo} command within the music notation.  These
are reflected in tempo changes in the MIDI output.  This command
will normally result in the metronome mark being printed, but this
can be suppressed, see @ref{Metronome marks}.  An alternative way
of specifying the initial or overall MIDI tempo is described below,
see @ref{MIDI block}.

Due to some limitations on Windows, the default extension for
MIDI files on Windows is @code{.mid}.  Other operating systems still
use the extension @code{.midi}.  If a different extension is preferred,
insert the following line at the top-level of the input file,
before the start of any @code{\book}, @code{\bookpart} or @code{\score} blocks:

@example
#(ly:set-option 'midi-extension "midi")
@end example

The line above will set the default extension for MIDI files to
@code{.midi}.

Alternatively, this option can also be supplied on the command line:

@example
lilypond … -dmidi-extension=midi lilyFile.ly
@end example


@unnumberedsubsubsec Instrument names

@cindex instrument names
@funindex Staff.midiInstrument

The MIDI instrument to be used is specified by setting the
@code{Staff.midiInstrument} property to the instrument name.
The name should be chosen from the list in @ref{MIDI instruments}.

@example
\new Staff @{
  \set Staff.midiInstrument = #"glockenspiel"
  @var{...notes...}
@}
@end example

@example
\new Staff \with @{midiInstrument = #"cello"@} @{
  @var{...notes...}
@}
@end example

If the selected instrument does not exactly match an instrument from
the list of MIDI instruments, the Grand Piano (@code{"acoustic grand"})
instrument is used.


@snippets

@lilypondfile[verbatim,quote,ragged-right,texidoc,doctitle]
{changing-midi-output-to-one-channel-per-voice.ly}

@knownissues

@c In 2.11 the following no longer seems to be a problem -td
@ignore
Unterminated (de)crescendos will not render properly in the midi file,
resulting in silent passages of music.  The workaround is to explicitly
terminate the (de)crescendo.  For example,

@example
@{ a4\< b c d\f @}
@end example

@noindent
will not work properly but

@example
@{ a4\< b c d\!\f @}
@end example

@noindent
will.
@end ignore

Changes in the MIDI volume take place only on starting a note, so
crescendi and decrescendi cannot affect the volume of a
single note.

Not all midi players correctly handle tempo changes in the midi
output.  Players that are known to work include MS Windows Media
Player and @uref{http://@/timidity@/.sourceforge@/.net/,timidity}.

@node MIDI block
@subsection MIDI block
@cindex MIDI block

A @code{\midi} block must appear within a score block if MIDI output
is required.  It is analogous to the layout block, but somewhat
simpler.  Often, the @code{\midi} block is left empty, but it
can contain context rearrangements, new context definitions or code
to set the values of properties.  For example, the following will
set the initial tempo exported to a MIDI file without causing a tempo
indication to be printed:

@example
\score @{
  @var{...music...}
  \midi @{
    \tempo 4 = 72
  @}
@}
@end example

In this example the tempo is set to 72 quarter note
beats per minute.  @code{\tempo} is actually a music command for
setting properties during the interpretation of music: in the
context of output definitions like a @code{\midi} block, as a matter of
courtesy those are reinterpreted as if they were context modifications.

@cindex MIDI context definitions

Context definitions follow precisely the same syntax as those
within a @code{\layout} block.  Translation modules for sound are
called performers.  The contexts for MIDI output are defined in
@file{../ly/performer-init.ly},
see @rlearning{Other sources of information}.
For example, to remove the effect of dynamics
from the MIDI output, insert the following lines in the
@code{\midi@{ @}} block.

@example
\midi @{
  ...
  \context @{
    \Voice
    \remove "Dynamic_performer"
  @}
@}
@end example

MIDI output is created only when a @code{\midi} block is included
within a score block defined with a @code{\score} command.

@example
\score @{
  @{ @dots{}notes@dots{} @}
  \midi @{ @}
@}
@end example

@node What goes into the MIDI output?
@subsection What goes into the MIDI output?

@c TODO Check grace notes - timing is suspect?

@unnumberedsubsubsec Supported in MIDI

@cindex Pitches in MIDI
@cindex MIDI, Pitches
@cindex Quarter tones in MIDI
@cindex MIDI, quarter tones
@cindex Microtones in MIDI
@cindex MIDI, microtones
@cindex Chord names in MIDI
@cindex MIDI, chord names
@cindex Rhythms in MIDI
@cindex MIDI, Rhythms
@cindex Articlulate scripts
@cindex MIDI, articulations
@cindex articulations in MIDI
@cindex trills in MIDI
@cindex turns in MIDI
@cindex rallentando in MIDI
@cindex accelerando in MIDI
@c TODO etc

The following items of notation are reflected in the MIDI output:

@itemize
@item Pitches
@item Microtones (See @ref{Accidentals}.  Rendering needs a
player that supports pitch bend.)
@item Chords entered as chord names
@item Rhythms entered as note durations, including tuplets
@item Tremolos entered without @q{@code{:}[@var{number}]}
@item Ties
@item Dynamic marks
@item Crescendi, decrescendi over multiple notes
@item Tempo changes entered with a tempo marking
@item Lyrics
@end itemize

Using @ref{The Articulate script}, a number of items are added to the
above list:

@itemize
@item Articulations (slurs, staccato, etc)
@item Trills, turns
@item Rallentando and accelerando
@end itemize


@unnumberedsubsubsec Unsupported in MIDI

@c TODO index as above

The following items of notation have no effect on the MIDI output,
unless you use @ref{The Articulate script}:

@itemize
@item Rhythms entered as annotations, e.g. swing
@item Tempo changes entered as annotations with no tempo marking
@item Staccato and other articulations and ornamentations
@item Slurs and Phrasing slurs
@item Crescendi, decrescendi over a single note
@item Tremolos entered with @q{@code{:}[@var{number}]}
@item Figured bass
@item Microtonal chords
@end itemize


@node Repeats in MIDI
@subsection Repeats in MIDI

@cindex repeats in MIDI
@funindex \unfoldRepeats

With a few minor additions, all types of repeats can be represented
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]
\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

In scores containing multiple voices, unfolding of repeats in MIDI
output will only occur correctly if @emph{each} voice contains fully
notated repeat indications.

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 Controlling MIDI dynamics
@subsection Controlling MIDI dynamics

MIDI dynamics are implemented by the Dynamic_performer which lives
by default in the Voice context.  It is possible to control the
overall MIDI volume, the relative volume of dynamic markings and
the relative volume of different instruments.

@unnumberedsubsubsec Dynamic marks

Dynamic marks are translated to a fixed fraction of the available
MIDI volume range.  The default fractions range from 0.25 for
@notation{ppppp} to 0.95 for @notation{fffff}.  The set of dynamic
marks and the associated fractions can be seen in
@file{../scm/midi.scm}, see @rlearning{Other sources of information}.
This set of fractions may be changed or extended by providing a
function which takes a dynamic mark as its argument and returns the
required fraction, and setting
@code{Score.dynamicAbsoluteVolumeFunction} to this function.

For example, if a @notation{rinforzando} dynamic marking,
@code{\rfz}, is required, this will not by default
have any effect on the MIDI volume, as this dynamic marking is not
included in the default set.  Similarly, if a new dynamic marking
has been defined with @code{make-dynamic-script} that too will not
be included in the default set.  The following example shows how the
MIDI volume for such dynamic markings might be added.  The Scheme
function sets the fraction to 0.9 if a dynamic mark of rfz is
found, or calls the default function otherwise.

@lilypond[verbatim,quote]
#(define (myDynamics dynamic)
    (if (equal? dynamic "rfz")
      0.9
      (default-dynamic-absolute-volume dynamic)))

\score {
  \new Staff {
    \set Staff.midiInstrument = #"cello"
    \set Score.dynamicAbsoluteVolumeFunction = #myDynamics
    \new Voice {
      \relative c'' {
        a4\pp b c-\rfz
      }
    }
  }
  \layout {}
  \midi {}
}
@end lilypond

Alternatively, if the whole table of fractions needs to be
redefined, it would be better to use the
@notation{default-dynamic-absolute-volume} procedure in
@file{../scm/midi.scm} and the associated table as a model.
The final example in this section shows how this might be done.

@unnumberedsubsubsec Overall MIDI volume

The minimum and maximum overall volume of MIDI dynamic markings is
controlled by setting the properties @code{midiMinimumVolume} and
@code{midiMaximumVolume} at the @code{Score} level.  These
properties have an effect only on dynamic marks, so if they
are to apply from the start of the score a dynamic mark must be
placed there.  The fraction corresponding to each dynamic mark is
modified with this formula

@example
midiMinimumVolume + (midiMaximumVolume - midiMinimumVolume) * fraction
@end example

In the following example the dynamic range of the overall MIDI
volume is limited to the range 0.2 - 0.5.

@lilypond[verbatim,quote]
\score {
  <<
    \new Staff {
      \key g \major
      \time 2/2
      \set Staff.midiInstrument = #"flute"
      \new Voice \relative c''' {
        r2 g\mp g fis~
        fis4 g8 fis e2~
        e4 d8 cis d2
      }
    }
    \new Staff {
      \key g \major
      \set Staff.midiInstrument = #"clarinet"
      \new Voice \relative c'' {
        b1\p a2. b8 a
        g2. fis8 e
        fis2 r
      }
    }
  >>
  \layout {}
  \midi {
    \tempo 2 = 72
    \context {
      \Score
      midiMinimumVolume = #0.2
      midiMaximumVolume = #0.5
    }
  }
}
@end lilypond

@unnumberedsubsubsec Equalizing different instruments (i)

If the minimum and maximum MIDI volume properties are set in
the @code{Staff} context the relative volumes of the MIDI
instruments can be controlled.  This gives a basic instrument
equalizer, which can enhance the quality of the MIDI output
remarkably.

In this example the volume of the clarinet is reduced relative
to the volume of the flute.  There must be a dynamic
mark on the first note of each instrument for this to work
correctly.

@lilypond[verbatim,quote]
\score {
  <<
    \new Staff {
      \key g \major
      \time 2/2
      \set Staff.midiInstrument = #"flute"
      \set Staff.midiMinimumVolume = #0.7
      \set Staff.midiMaximumVolume = #0.9
      \new Voice \relative c''' {
        r2 g\mp g fis~
        fis4 g8 fis e2~
        e4 d8 cis d2
      }
    }
    \new Staff {
      \key g \major
      \set Staff.midiInstrument = #"clarinet"
      \set Staff.midiMinimumVolume = #0.3
      \set Staff.midiMaximumVolume = #0.6
      \new Voice \relative c'' {
        b1\p a2. b8 a
        g2. fis8 e
        fis2 r
      }
    }
  >>
  \layout {}
  \midi {
    \tempo 2 = 72
  }
}
@end lilypond

@unnumberedsubsubsec Equalizing different instruments (ii)

If the MIDI minimum and maximum volume properties are not set
LilyPond will, by default, apply a small degree of equalization
to a few instruments.  The instruments and the equalization
applied are shown in the table @notation{instrument-equalizer-alist}
in @file{../scm/midi.scm}.

This basic default equalizer can be replaced by setting
@code{instrumentEqualizer} in the @code{Score} context to a new
Scheme procedure which accepts a MIDI instrument name as its only
argument and returns a pair of fractions giving the minimum and
maximum volumes to be applied to that instrument.  This replacement
is done in the same way as shown for resetting the
@code{dynamicAbsoluteVolumeFunction} at the start of this section.
The default equalizer, @notation{default-instrument-equalizer}, in
@file{../scm/midi.scm} shows how such a procedure might be written.

The following example sets the relative flute and clarinet volumes
to the same values as the previous example.

@lilypond[verbatim,quote]
#(define my-instrument-equalizer-alist '())

#(set! my-instrument-equalizer-alist
  (append
    '(
      ("flute" . (0.7 . 0.9))
      ("clarinet" . (0.3 . 0.6)))
    my-instrument-equalizer-alist))

#(define (my-instrument-equalizer s)
  (let ((entry (assoc s my-instrument-equalizer-alist)))
    (if entry
      (cdr entry))))

\score {
  <<
    \new Staff {
      \key g \major
      \time 2/2
      \set Score.instrumentEqualizer = #my-instrument-equalizer
      \set Staff.midiInstrument = #"flute"
      \new Voice \relative c''' {
        r2 g\mp g fis~
        fis4 g8 fis e2~
        e4 d8 cis d2
      }
    }
    \new Staff {
      \key g \major
      \set Staff.midiInstrument = #"clarinet"
      \new Voice \relative c'' {
        b1\p a2. b8 a
        g2. fis8 e
        fis2 r
      }
    }
  >>
  \layout { }
  \midi {
    \tempo 2 = 72
  }
}
@end lilypond

@ignore
@c Delete when satisfied this is adequately covered elsewhere -td

@n ode Microtones in MIDI
@s ubsection Microtones in MIDI

@cindex microtones in MIDI

Microtones consisting of half sharps and half flats are exported
to the MIDI file and render correctly in MIDI players which support
pitch bending.  See @ref{Note names in other languages}.  Here is
an example showing all the half sharps and half flats.  It can be
copied out and compiled to test microtones in your MIDI player.

@lilypond[verbatim,quote]
\score {
  \relative c' {
    c4 cih cis cisih
    d4 dih ees eeh
    e4 eih f fih
    fis4 fisih g gih
    gis4 gisih a aih
    bes4 beh b bih
  }
  \layout {}
  \midi {}
}
@end lilypond
@end ignore


@node Percussion in MIDI
@subsection Percussion in MIDI

Percussion instruments are generally notated in a @code{DrumStaff}
context and when notated in this way they are outputted correctly
to MIDI channel@tie{}10, but some pitched percussion instruments,
like the xylophone, marimba, vibraphone, timpani, etc., are
treated like @qq{normal} instruments and music for these instruments
should be entered in a normal @code{Staff} context, not a
@code{DrumStaff} context, to obtain the correct MIDI output.

Some non-pitched percussion sounds included in the general MIDI
standard, like melodic tom, taiko drum, synth drum, etc., cannot
be reached via MIDI channel@tie{}10, so the notation for such
instruments should also be entered in a normal @code{Staff}
context, using suitable normal pitches.

Many percussion instruments are not included in the general MIDI
standard, e.g. castanets.  The easiest, although unsatisfactory,
method of producing some MIDI output when writing for such
instruments is to substitute the nearest sound from the standard
set.

@c TODO Expand with examples, and any other issues

@knownissues

Because the general MIDI standard does not contain rim shots, the
sidestick is used for this purpose instead.

@node The Articulate script
@subsection The Articulate script

A more realistic MIDI output is possible when using the Articulate
script.  It tries to take articulations (slurs, staccato, etc) into
account, by replacing notes with sequential music of suitably
time-scaled note plus skip.  It also tries to unfold trills turns
etc., and take rallentando and accelerando into account.

To use the Articulate script, you have to include it at the top of
your input file,

@example
\include "articulate.ly"
@end example

and in the @code{\score} section do

@example
\unfoldRepeats \articulate <<
        all the rest of the score...
>>
@end example

After altering your input file this way, the visual output is heavily
altered, but the standard @code{\midi} block will produce a better
MIDI file.

Although not essential for the Articulate script to work, you may want
to insert the @code{\unfoldRepeats} command as it appears in the
example shown above as it enables performing abbreviatures such as
@notation{trills}.

@knownissues

Articulate shortens chords and some music (esp. organ music) could
sound worse.


@node Extracting musical information
@section Extracting musical information

In addition to creating graphical output and MIDI, LilyPond can
display musical information as text.

@menu
* Displaying LilyPond notation::
* Displaying scheme music expressions::
* Saving music events to a file::
@end menu

@node Displaying LilyPond notation
@subsection Displaying LilyPond notation

@funindex \displayLilyMusic
Displaying a music expression in LilyPond notation can be
done with the music function @code{\displayLilyMusic}.  To see the
output, you will typically want to call LilyPond using the command
line.  For example,

@example
@{
  \displayLilyMusic \transpose c a, @{ c4 e g a bes @}
@}
@end example

will display

@example
@{ a,4 cis e fis g @}
@end example

By default, LilyPond will print these messages to the console
along with all the other LilyPond compilation messages.  To split
up these messages and save the results of @code{\display@{STUFF@}},
redirect the output to a file.

@example
lilypond file.ly >display.txt
@end example

@funindex \void
Note that Lilypond does not just display the music expression, but
also interprets it (since @code{\displayLilyMusic} returns it in
addition to displaying it).  This is convenient since you can just
insert @code{\displayLilyMusic} into existing music in order to get
information about it.  If you don't actually want Lilypond to
interpret the displayed music as well as display it, use @code{\void}
in order to have it ignored:

@example
@{
  \void \displayLilyMusic \transpose c a, @{ c4 e g a bes @}
@}
@end example


@node Displaying scheme music expressions
@subsection Displaying scheme music expressions

See @rextend{Displaying music expressions}.


@node Saving music events to a file
@subsection Saving music events to a file

Music events can be saved to a file on a per-staff basis by
including a file in your main score.

@example
\include "event-listener.ly"
@end example

This will create file(s) called @file{FILENAME-STAFFNAME.notes} or
@file{FILENAME-unnamed-staff.notes} for each staff.  Note that if
you have multiple unnamed staves, the events for all staves will
be mixed together in the same file.  The output looks like this:

@example
0.000   note     57       4   p-c 2 12
0.000   dynamic  f
0.250   note     62       4   p-c 7 12
0.500   note     66       8   p-c 9 12
0.625   note     69       8   p-c 14 12
0.750   rest     4
0.750   breathe
@end example

The syntax is a tab-delimited line, with two fixed fields on each
line followed by optional parameters.

@example
@var{time}  @var{type}  @var{...params...}
@end example

This information can easily be read into other programs such as
python scripts, and can be very useful for researchers wishing to
perform musical analysis or playback experiments with LilyPond.


@knownissues

Not all lilypond music events are supported by
@file{event-listener.ly}.  It is intended to be a well-crafted
@qq{proof of concept}.  If some events that you want to see are
not included, copy @file{event-listener.ly} into your lilypond
directory and modify the file so that it outputs the information
you want.