@end quotation
@noindent
-You may find it useful to review @ruser{Music expressions
+You may find it useful to review @ref{Music expressions
explained}. In that section, we saw how to build big music
expressions from small pieces -- we started from notes, then
chords, etc. Now we're going to start from a big music expression
@}
@end example
-Remember that we use @code{<<} and @code{>>} to show simultaneous
+Remember that we use @code{<<} and @code{>>} to show concurrent
music. And we definitely want to show the vocal part and piano
part at the same time, not one after the other!
@example
melody = @{ @}
-text = @{ @}
-upper = @{ @}
-lower = @{ @}
+text = @{ @}
+upper = @{ @}
+lower = @{ @}
\score @{
@{
<<
@end example
@noindent
-Remember that you can use almost any name you like. The
+Remember that you can use almost any name you like as long
+as it contains just alphabetic characters. The exact
limitations on variable names are detailed in @ruser{File
structure}.
fundamental thing that includes music in lilypond.
@menu
-* I'm seeing Voices::
+* I'm hearing Voices::
* Explicitly instantiating voices::
* Voices and vocals::
@end menu
-@c too cheesy? I'm not certain. -gp
-@node I'm seeing Voices
-@subsection I'm seeing Voices
+@node I'm hearing Voices
+@subsection I'm hearing Voices
@cindex polyphony
+@cindex layers
+@cindex Voice context
+
+The lowest, most fundamental or innermost layers in a LilyPond
+score are called Voices. Voices are sometimes
+called @q{layers} in other notation packages. In LilyPond they
+are called @q{Voice contexts}.
+
+In fact, a Voice layer or context is the only one which can
+contain music. If a Voice context is not explicitly declared
+one is created automatically. Some instruments such as an
+Oboe can play only one note at a time and music written for
+such instruments is monophonic and requires just a single
+voice. Instruments which can play more than one note at a
+time like the piano will often require multiple voices to
+encode the different concurent notes and rhythms they are
+capable of playing.
+
+A single voice can contain many notes in a chord, of course,
+so when exactly are multiple voices needed?
+Let us analyse a short piece of music to see how many voices
+are required. Here are the notes from the first two bars
+of the second of Chopin's Deux Nocturnes, Op 32.
+
+@c The following should appear as music without code
+@lilypond[quote,ragged-right]
+\new Staff \relative c'' {
+ \key aes \major
+ <<
+ { \voiceOne
+ c2 aes4. bes8 } \\
+ { \voiceTwo
+ aes2 f4 fes } \\
+ { \voiceFour
+ \once \override NoteColumn #'force-hshift = #0 <ees c>2
+ \once \override NoteColumn #'force-hshift = #0.5 des2 }
+ >> |
+ <c ees aes c>1 |
+}
+@end lilypond
-TODO: add intro about voices vs. layers vs. whatever.
-
-TODO: sex this up with colors and stuff. -gp
+The direction of the stems is often used to indicate the
+continuity of two concurrent melodic lines. Here the
+stems of the highest notes are all pointing up and the
+stems of the lower notes are all pointing down.
+This is the first indication that more than one voice
+is required.
+
+But the real need for multiple voices arises when notes
+which start at the same time have different durations.
+Look at the notes which start at beat three in the first
+bar. The a-flat is a dotted quarter note, the f is a
+quarter note and the d-flat is a half note. These
+cannot be written as a chord as all the notes in a chord
+must have the same duration. Neither can they be written
+as sequential notes, as they must start at the same time.
+This section of the bar requires three voices, and the
+normal practice would be to write the whole bar as three
+voices, as shown here, where we have coloured the three
+voices differently.
+
+@c The following should appear as music without code
+@lilypond[quote,ragged-right]
+\new Staff \relative c'' {
+ \key aes \major
+ <<
+ { \voiceOne
+ \override NoteHead #'color = #red
+ \override Stem #'color = #red
+ c2 aes4. bes8 } \\
+ { \voiceTwo
+ \override NoteHead #'color = #blue
+ \override Stem #'color = #blue
+ aes2 f4 fes } \\
+ { \voiceFour
+ \override NoteHead #'color = #green
+ \override Stem #'color = #green
+ \once \override NoteColumn #'force-hshift = #0 <ees c>2
+ \once \override NoteColumn #'force-hshift = #0.5 des2 }
+ >> |
+ <c ees aes c>1 |
+}
+@end lilypond
-TODO: actually, a general rewrite is needed. -gp
+Let us see how this is done.
+@funindex \\
The easiest way to enter fragments with more than one voice on a
staff is to enter each voice as a sequence (with @code{@{...@}}),
-and combine them simultaneously, separating the voices with
-@code{\\}
+and combine them concurrently with angle brackets, @code{<<...>>}.
+The fragments must also be separated with double backward slashes,
+@code{\\}, to place them in separate voices. Without these, the
+notes would be entered into a single voice, which would usually
+cause errors. This technique is particularly suited to pieces of
+music which are largely monophonic with occasional short sections
+of polyphony. Here's a simple example:
+
+@lilypond[quote,verbatim,fragment,ragged-right,relative=2]
+\key d \minor
+% Voice "1" Voice "2"
+<< { r4 g g4. a8 } \\ { d,2 d4 g } >> |
+<< { bes4 bes c bes } \\ { g4 g g8( a) g4 } >> |
+<< { a2. r4 } \\ { fis2. s4 } >>
+@end lilypond
-@funindex \\
+This example has just two voices, but the same contruct may be
+used to encode three or more voices by adding more back-slash
+separators.
+
+The Voice contexts bear the names @code{"1"}, @code{"2"}, etc.
+In each of these contexts, vertical direction of slurs, stems, ties,
+dynamics etc., is set appropriately.
@lilypond[quote,verbatim,fragment]
\new Staff \relative c' {
+ % Main voice
c16 d e f
- <<
- { g4 f e | d2 e2 } \\
- { r8 e4 d c8 ~ | c b16 a b8 g ~ g2 } \\
- { s2. | s4 b4 c2 }
- >>
+ % Voice "1" Voice "2" Voice "3"
+ << { g4 f e } \\ { r8 e4 d c8 ~ } >> |
+ << { d2 e2 } \\ { c8 b16 a b8 g ~ g2 } \\ { s4 b4 c2 } >> |
}
@end lilypond
-@cindex layers
-
-The separator causes @internalsref{Voice}
-contexts@footnote{Polyphonic voices are sometimes
-called @q{layers} in other notation packages} to be instantiated.
-They bear the names @code{"1"}, @code{"2"}, etc. In each of these
-contexts, vertical direction of slurs, stems, etc., is set
-appropriately.
-
-These voices are all separate from the voice that contains the
-notes just outside the @code{<< \\ >>} construct. This should be
-noted when making changes at the voice level. This also means
-that slurs and ties cannot go into or out of a @code{<< \\ >>}
+These voices are all separate from the main voice that contains
+the notes just outside the @code{<< \\ >>} construct. Slurs and
+ties may only connect notes within the same voice, so
+slurs and ties cannot go into or out of a @code{<< \\ >>}
construct. Conversely, parallel voices from separate @code{<< \\
->>} constructs on the same staff are the same voice. Here is the
-same example, with different noteheads and colors for each voice.
-Note that the change to the note-head style in the main voice does
+>>} constructs on the same staff are the same voice. Other voice-
+related properties also carry across @code{<< \\ >>} constructs.
+Here is the
+same example, with different colors for each voice.
+Note that changing the colour of the main voice to red does
not affect the inside of the @code{<< \\ >>} constructs. Also,
-the change to the second voice in the first @code{<< \\ >>}
-construct is effective in the second @code{<< \\ >>}, and the
-voice is tied across the two constructs.
-
-@cindex note heads, styles
-
+changing the colour of the second voice to blue in the first
+@code{<< \\ >>} construct is effective in the second
+@code{<< \\ >>} construct. Note that tied notes may be split
+across the same voices in two constructs, shown here in the
+blue voice.
+
+@cindex notehead colour
+@cindex stem colour
+@cindex beam colour
+
+@ignore
+TODO: Consider whether to retain the style changes - I think they
+ spoil the appearance, so I've commented them out. If we are
+ to retain colour, I'd prefer to colour the stems and beams
+ too, as here. -td
+TODO: Check that these color overrides have been introduced
+ earlier in the LM. -td
+@end ignore
@lilypond[quote,verbatim,fragment]
\new Staff \relative c' {
- \override NoteHead #'style = #'cross
+% \override NoteHead #'style = #'cross
\override NoteHead #'color = #red
+ \override Stem #'color = #red
+ \override Beam #'color = #red
c16 d e f
- <<
+ << % Bar 1
{ g4 f e } \\
- { \override NoteHead #'style = #'triangle
+ {
+% \override NoteHead #'style = #'triangle
\override NoteHead #'color = #blue
- r8 e4 d c8 ~ }
+ \override Stem #'color = #blue
+ \override Beam #'color = #blue
+ r8 e4 d c8 ~
+ }
>> |
- <<
+ << % Bar 2
{ d2 e2 } \\
{ c8 b16 a b8 g ~ g2 } \\
- { \override NoteHead #'style = #'slash
+ {
+% \override NoteHead #'style = #'slash
\override NoteHead #'color = #green
- s4 b4 c2 }
+ \override Stem #'color = #green
+ \override Beam #'color = #green
+ s4 b4 c2
+ }
>>
}
@end lilypond
Polyphony does not change the relationship of notes within a
@code{\relative @{ @}} block. Each note is calculated relative to
-the note immediately preceding it.
+the note immediately preceding it, or to the first note of the
+preceding chord.
@example
-\relative @{ noteA << noteB \\ noteC >> noteD @}
+\relative @{ noteA << <noteB noteC> \\ noteD >> noteE @}
@end example
+@code{noteB} is relative to @code{noteA}
@code{noteC} is relative to @code{noteB}, not @code{noteA};
-@code{noteD} is relative to @code{noteC}, not @code{noteB} or
-@code{noteA}.
+@code{noteD} is relative to @code{noteB}, not @code{noteA} or
+@code{noteC}.
+@code{noteE} is relative to @code{noteD}, not @code{noteA}
+
+We are now in a position to return to the first example from
+the Chopin Nocturne to see how this might be encoded. As we
+shall see, this encounters some difficulties. We begin as
+we have learnt, using the @code{<< \\ >>} construct to
+enter the music of the first bar in three voices:
+
+@lilypond[quote,verbatim,fragment,ragged-right]
+\new Staff \relative c'' {
+ \key aes \major
+ <<
+ { c2 aes4. bes8 } \\ { aes2 f4 fes } \\ { <ees c>2 des2 }
+ >> |
+ <c ees aes c>1 |
+}
+@end lilypond
+
+@cindex stem down
+@cindex stem up
+@funindex \stemDown
+@funindex \stemUp
+
+The stem directions are automatically assigned with the
+odd-numbered voices taking upward stems and the even-numbered
+voices downward ones. The stems for voices 1 and 2 are right,
+but the stems in voice 3 should go down in this particular piece
+of music. We can correct this
+by using the @code{\stemDown} command. There is also a
+corresponding @code{\stemUp} command. These may be used
+in any music stream to change the direction of the stems
+of the following notes. Let's use @code{\stemDown} to
+correct our third voice. This result in the following:
+
+@lilypond[quote,verbatim,fragment,ragged-right]
+\new Staff \relative c'' {
+ \key aes \major
+ <<
+ { c2 aes4. bes8 } \\
+ { aes2 f4 fes } \\
+ { \stemDown <ees c>2 des2 }
+ >> |
+ <c ees aes c>1 |
+}
+@end lilypond
+@noindent
+and exposes a problem commonly encountered with multiple
+voices: the stems of notes can collide with noteheads
+in other voices. In laying out the notes, LilyPond allows the
+notes or chords from two voices to occupy the same vertical
+note column provided the stems are in opposite directions, but
+the notes from a third voice are displaced to avoid the stems
+colliding. This often works well, but in this example the
+notes of the third voice are clearly not well placed by default.
+LilyPond provides several ways to adjust the horizontal placing
+of notes. These are described in the Notation Reference.
+We introduce just one here, the @code{force-hshift} property of
+@code{NoteColumn}. The lower two notes of the first chord (i.e,
+those in the third voice) should not be shifted away from the
+note column of the higher two notes. To correct this we set
+@code{force-hshift} of these notes to zero.
+The lower note of the second chord is best placed just to the
+right of the higher notes. We achieve this by setting
+@code{force-hshift} of this note to 0.5, ie half a notehead's
+width to the right of the note column of the higher notes.
+
+Here's the final result:
+
+@lilypond[quote,verbatim,fragment,ragged-right]
+\new Staff \relative c'' {
+ \key aes \major
+ <<
+ { c2 aes4. bes8 } \\
+ { aes2 f4 fes } \\
+ { \stemDown
+ \once \override NoteColumn #'force-hshift = #0 <ees c>2
+ \once \override NoteColumn #'force-hshift = #0.5 des2
+ }
+ >> |
+ <c ees aes c>1 |
+}
+@end lilypond
@node Explicitly instantiating voices
@subsection Explicitly instantiating voices
-TODO: more colors and stuff.
-
-@internalsref{Voice} contexts can also be instantiated manually
+Voice contexts can also be created manually
inside a @code{<< >>} block to create polyphonic music, using
-@code{\voiceOne}, up to @code{\voiceFour} to assign stem
-directions and a horizontal shift for each part.
+@code{\voiceOne}, up to @code{\voiceFour} to automatically assign
+the directions of stems, slurs, etc.
+
+Specifically, the construct @code{<< \\ >>} which we used in
+the previous section:
-Specifically,
@example
<< \upper \\ \lower >>
@end example
@noindent
-is equivalent to
+where @code{upper} and @code{lower} are user-defined variables
+containing the music for the two voices, is equivalent to
@example
<<
ties, articulations, text annotations, augmentation dots of dotted
notes, and fingerings. @code{\voiceOne} and @code{\voiceThree}
make these objects point upwards, while @code{\voiceTwo} and
-@code{\voiceFour} make them point downwards. The command
-@code{\oneVoice} will revert back to the normal setting.
+@code{\voiceFour} make them point downwards. These commands also
+generate a horizontal shift for each voice when this is required
+to avoid clashes of note heads. The command @code{\oneVoice}
+reverts the settings back to the normal values for a single voice.
An expression that appears directly inside a @code{<< >>} belongs
to the main voice. This is useful when extra voices appear while
the main voice is playing. Here is a more correct rendition of
-the example from the previous section. The crossed colored
-noteheads demonstrate that the main melody is now in a single
-voice context.
+the example from the previous section. The red-coloured
+notes demonstrate that the main melody is now in a single
+voice context, permitting a phrasing slur to be drawn over them.
@lilypond[quote,ragged-right,verbatim]
\new Staff \relative c' {
- \override NoteHead #'style = #'cross
\override NoteHead #'color = #red
- c16 d e f
- \voiceOne
- <<
- { g4 f e | d2 e2 }
- \new Voice="1" { \voiceTwo
+ \override Stem #'color = #red
+ \override Beam #'color = #red
+ c16^( d e f % These notes are monophonic
+ << % Start concurrent section of three voices
+ { g4 f e | d2 e2) } % Continue the main voice in parallel
+ \new Voice { % Initiate second voice
+ \voiceTwo % Set stems, etc, down
r8 e4 d c8 ~ | c8 b16 a b8 g ~ g2
- \oneVoice
}
- \new Voice { \voiceThree
+ \new Voice { % Initiate third voice
+ \voiceThree % Set stems, etc, up
s2. | s4 b4 c2
- \oneVoice
}
>>
- \oneVoice
}
@end lilypond
-The correct definition of the voices allows the melody to be
-slurred.
-
-@lilypond[quote,ragged-right,verbatim]
-\new Staff \relative c' {
- c16^( d e f
- \voiceOne
- <<
- { g4 f e | d2 e2) }
- \context Voice="1" { \voiceTwo
- r8 e4 d c8 ~ | c8 b16 a b8 g ~ g2
- \oneVoice
- }
- \new Voice { \voiceThree
- s2. s4 b4 c2
- \oneVoice
- }
- >>
- \oneVoice
-}
-@end lilypond
+@cindex nesting music expressions
+@cindex nesting concurrent constructs
-Avoiding the @code{\\} separator also allows nesting polyphony
-constructs, which in some case might be a more natural way to
+More deeply nested polyphony constructs are possible, and if a
+voice appears only briefly this might be a more natural way to
typeset the music.
@lilypond[quote,ragged-right,verbatim]
\new Staff \relative c' {
c16^( d e f
- \voiceOne
<<
{ g4 f e | d2 e2) }
- \context Voice="1" { \voiceTwo
+ \new Voice {
+ \voiceTwo
r8 e4 d c8 ~ |
<<
{c8 b16 a b8 g ~ g2}
- \new Voice { \voiceThree
+ \new Voice {
+ \voiceThree
s4 b4 c2
- \oneVoice
}
>>
- \oneVoice
}
>>
- \oneVoice
}
@end lilypond
+This method of nesting new voices briefly is useful
+when only small sections of the music
+are polyphonic, but when the whole staff is largely polyphonic
+it can be clearer to use multiple voices throughout and use
+spacing notes to step over sections where the voice is silent,
+as here:
+
+@lilypond[quote,ragged-right,verbatim]
+\new Staff \relative c' <<
+ \new Voice { % Initiate first voice
+ \voiceOne
+ c16^( d e f g4 f e | d2 e2) |
+ }
+ \new Voice { % Initiate second voice
+ \voiceTwo % set stems, etc down
+ s4 r8 e4 d c8 ~ | c8 b16 a b8 g ~ g2 |
+ }
+ \new Voice { % Initiate third voice
+ \voiceThree % set stems, etc up
+ s1 | s4 b4 c2 |
+ }
+>>
+@end lilypond
+
+
+
@node Voices and vocals
@subsection Voices and vocals
@menu
* On the un-nestedness of brackets and ties::
-* Up and down::
-* Distances and measurements MAYBE MOVE::
@end menu
@c my name start sucking the more docs I write. -gp
TODO... add more info? Fluff up the first sentence?
-@node Up and down
-@subsection Up and down
-
-TODO: everything
-
-By default, lilypnod does a pretty jazz'n job of picking
-directions. But in some cases, it may be desirable to force a
-direction.
-
-@verbatim
--
-^ _
-@end verbatim
-
-
-@node Distances and measurements MAYBE MOVE
-@subsection Distances and measurements MAYBE MOVE
-
-DISCUSS after working on other sections.
-
-TODO: staff spaces, #UP #DOWN #LEFT #RIGHT. Maybe move into tweaks?
-
-
-
@node Extending the templates
@section Extending the templates
projects / lilypond.git / commitdiff