2 @c This file is part of lilypond.tely
7 LilyPond is a system for formatting music prettily. This chapter
8 discusses the backgrounds of LilyPond. It explains the problem of
9 printing music with computers, and our approach to solving those
15 * Automated engraving::
16 * What symbols to engrave?::
17 * Music representation::
18 * Example applications::
26 The art of music typography is called @emph{(plate) engraving}. The
27 term derives from the traditional process of music printing. Just a
28 few decades ago, sheet music was made by cutting and stamping the
29 music into a zinc or pewter plate in mirror image. The plate would be
30 inked, the depressions caused by the cutting and stamping would hold
31 ink. An image was formed by pressing paper to the plate. The
32 stamping and cutting was completely done by hand. Making a correction
33 was cumbersome, if possible at all, so the engraving had to be perfect
34 in one go. Engraving was a highly specialized skill, a craftsman had
35 to complete around ten years of practical training before he could be
38 Nowadays, all newly printed music is produced with computers. This
39 has obvious advantages; prints are cheaper to make, editorial work can
40 be delivered by email. Unfortunately, the pervasive use of computers
41 has also decreased the graphical quality of scores. Computer
42 printouts have a bland, mechanical look, which makes them unpleasant
46 @c introduce illustrating aspects of engraving, font...
47 The images below illustrate the difference between traditional
48 engraving and typical computer output, and the third picture shows how
49 LilyPond mimics the traditional look. The left picture shows a scan
50 of a flat symbol from a Henle edition published in 2000. The center
51 depicts a symbol from a hand-engraved B@"{a}renreiter edition of the
52 same music. The left scan illustrates typical flaws of computer
53 print: the staff lines are thin, the weight of the flat symbol matches
54 the light lines and it has a straight layout with sharp corners. By
55 contrast, the B@"{a}renreiter flat has a bold, almost voluptuous
56 rounded look. Our flat symbol is designed after, among others, this
57 one. It is rounded, and its weight harmonizes with the thickness of
58 our staff lines, which are also much thicker than Henle's lines.
60 @multitable @columnfractions .05 .3 .3 .3 .05
64 @image{henle-flat-bw,4cm}
67 @image{henle-flat-bw,,,png}
72 @image{baer-flat-bw,4cm}
75 @image{baer-flat-bw,,,png}
80 @image{lily-flat-bw,4cm}
83 @image{lily-flat-bw,,,png}
87 @c workaround for makeinfo-4.6: line breaks and multi-column cookies
88 @image{henle-flat-bw,,,png} @image{baer-flat-bw,,,png} @image{lily-flat-bw,,,png}
94 B@"{a}renreiter (1950)
96 LilyPond Feta font (2003)
101 @cindex musical symbols
106 @c introduce illustrating aspects of engraving, spacing...
107 In spacing, the distribution of space should reflect the durations
108 between notes. However, many modern scores adhere to the durations
109 with mathematical precision, which leads to poor results. In the
110 next example a motive is printed twice. It is printed once using
111 exact mathematical spacing, and once with corrections. Can you
112 spot which fragment is which?
114 @cindex optical spacing
115 @lilypond[quote,noindent]
118 \override Staff.NoteSpacing #'stem-spacing-correction = #0.6
120 \stemDown b'4 e''4 a'4 e''4 | \bar "||"
121 \override Staff.NoteSpacing #'stem-spacing-correction = #0.0
122 \override Staff.StaffSpacing #'stem-spacing-correction = #0.0
123 \stemBoth c'4 e''4 e'4 b'4 |
124 \stemDown b'4 e''4 a'4 e''4 |
126 \paper { raggedright = ##t }
130 @cindex regular rhythms
131 @cindex regular spacing
133 The fragment only uses quarter notes: notes that are played in a
134 constant rhythm. The spacing should reflect that. Unfortunately, the
135 eye deceives us a little; not only does it notice the distance between
136 note heads, it also takes into account the distance between
137 consecutive stems. As a result, the notes of an up-stem/down-stem
138 combination should be put farther apart, and the notes of a down-up
139 combination should be put closer together, all depending on the
140 combined vertical positions of the notes. The first two measures are
141 printed with this correction, the last two measures without. The notes
142 in the last two measures form down-stem/up-stem clumps of notes.
146 Musicians are usually more absorbed with performing than with studying
147 the looks of piece of music; nitpicking about typographical details
148 may seem academical. But it is not. In larger pieces with monotonous
149 rhythms, spacing corrections lead to subtle variations in the layout
150 of every line, giving each one a distinct visual signature. Without
151 this signature all lines would look the same, they become like a
152 labyrinth. If the musician looks away once or has a lapse in his
153 concentration, he will be lost on the page.
156 Similarly, the strong visual look of bold symbols on heavy staff lines
157 stands out better when music is far away from reader, for example, if
158 it is on a music stand. A careful distribution of white space allows
159 music to be set very tightly without cluttering symbols together. The
160 result minimizes the number of page turns, which is a great advantage.
162 This is a common characteristic of typography. Layout should be
163 pretty, not only for its own sake, but especially because it helps the
164 reader in his task. For performance material like sheet music, this is
165 of double importance: musicians have a limited amount of attention. The
166 less attention they need for reading, the more they can focus on
167 playing itself. In other words, better typography translates to better
170 Hopefully, these examples also demonstrate that music typography is an
171 art that is subtle and complex, and to produce it requires
172 considerable expertise, which musicians usually do not have. LilyPond
173 is our effort to bring the graphical excellence of hand-engraved music
174 to the computer age, and make it available to normal musicians. We
175 have tuned our algorithms, font-designs, and program settings to
176 produce prints that match the quality of the old editions we love to
177 see and love to play from.
182 @node Automated engraving
183 @section Automated engraving
185 How do we go about implementing typography? If craftsmen need over
186 ten years to become true masters, how could we simple hackers ever
187 write a program to take over their jobs?
189 The answer is: we cannot. Typography relies on human judgment of
190 appearance, so people cannot be replaced ultimately. However, much of
191 the dull work can be automated. If LilyPond solves most of the common
192 situations correctly, this will be a huge improvement over existing
193 software. The remaining cases can be tuned by hand. Over the course
194 of years, the software can be refined to do more and more
195 automatically, so manual overrides are less and less necessary.
197 When we started we wrote the LilyPond program entirely in the C++
198 programming language; the program's functionality was set in stone by
199 the developers. That proved to be unsatisfactory for a number of
203 @item When LilyPond makes mistakes,
204 users need to override formatting decisions. Therefore, the user must
205 have access to the formatting engine. Hence, rules and settings cannot
206 be fixed by us at compile time but must be accessible for users at
209 @item Engraving is a matter of visual judgment, and therefore a matter of
210 taste. As knowledgeable as we are, users can disagree with our
211 personal decisions. Therefore, the definitions of typographical style
212 must also be accessible to the user.
214 @item Finally, we continually refine the formatting algorithms, so we
215 need a flexible approach to rules. The C++ language forces a certain
216 method of grouping rules that do not match well with how music
220 These problems have been addressed by integrating the GUILE
221 interpreter for the Scheme programming language and rewriting parts of
222 LilyPond in Scheme. The new, flexible formatting is built around the
223 notion of graphical objects, described by Scheme variables and
224 functions. This architecture encompasses formatting rules,
225 typographical style and individual formatting decisions. The user has
226 direct access to most of these controls.
228 Scheme variables control layout decisions. For example, many
229 graphical objects have a direction variable that encodes the choice
230 between up and down (or left and right). Here you see two chords,
231 with accents and arpeggio. In the first chord, the graphical objects
232 have all directions down (or left). The second chord has all
233 directions up (right).
235 @lilypond[quote,raggedright,relative=1]
237 \override SpacingSpanner #'spacing-increment = #3
238 \override TimeSignature #'transparent = ##t
240 \stemDown <e g b>4_>-\arpeggio
241 \override Arpeggio #'direction = #RIGHT
242 \stemUp <e g b>4^>-\arpeggio
246 The process of formatting a score consists of reading and writing the
247 variables of graphical objects.
249 Some variables have a preset value. For example, the thickness of many
250 lines---a characteristic of typographical style---are preset
251 variables. Changing them gives a different typographical impression.
253 @lilypond[quote,raggedright]
256 c'4-~ c'16 as g f e16 g bes c' des'4
262 \override Beam #'thickness = #0.3
263 \override Stem #'thickness = #0.5
264 \override Bar #'thickness = #3.6
265 \override Tie #'thickness = #2.2
266 \override StaffSymbol #'thickness = #3.0
267 \override Tie #'extra-offset = #'(0 . 0.3)
273 Formatting rules are also preset variables: each object has variables
274 containing procedures. These procedures perform the actual formatting,
275 and by substituting different ones, we can change behavior. In the
276 following example, the rule which note head objects use to produce
277 their symbol is changed during the music fragment.
279 @lilypond[quote,raggedright]
280 #(define (mc-squared grob orig current)
281 (let ((interfaces (ly:grob-property grob 'interfaces))
282 (pos (ly:grob-property grob 'staff-position)))
283 (if (and (memq 'note-head-interface interfaces)
284 (memq pos '(-2 -3 -5)))
286 (ly:grob-set-property! grob 'print-function brew-new-markup-stencil)
287 (ly:grob-set-property! grob 'font-family 'roman)
288 (ly:grob-set-property!
293 ((-5) (make-simple-markup "m"))
294 ((-3) (make-simple-markup "c "))
295 ((-2) (make-smaller-markup (make-bold-markup "2")))
296 (else (make-simple-markup "bla")))))))))
299 \notes \context Voice \relative c' {
301 \set autoBeaming = ##f
304 \once \override NoteHead #'print-function = #Note_head::brew_ez_stencil
306 \once \override NoteHead #'style = #'cross
308 \applyoutput #mc-squared
311 { d8[ es-( fis^^ g] fis2-) }
312 \repeat unfold 5 { \applyoutput #mc-squared s8 }
320 @node What symbols to engrave?
321 @section What symbols to engrave?
326 The formatting process in LilyPond decides where to place
327 symbols. However, this can only be done once it is decided @emph{what}
328 symbols should be printed, in other words what notation to use.
330 Common music notation is a system of recording music that has evolved
331 over the past 1000 years. The form that is now in common use, dates
332 from the early renaissance. Although the basic form (i.e., note heads on a
333 5-line staff) has not changed, the details still change to express the
334 innovations of contemporary notation. Hence, it encompasses some 500
335 years of music. Its applications range from monophonic melodies to
336 monstrous counterpoint for large orchestras.
338 How can we get a grip on such a many-headed beast, and force it into
339 the confines of a computer program? We have broken up the problem of
340 notation (as opposed to engraving, i.e., typography) into digestible
341 and programmable chunks: every type of symbol is handled by a separate
342 module, a so-called plug-in. Each plug-in is completely modular and
343 independent, so each can be developed and improved separately. People
344 who translate musical ideas to graphic symbols are called copyists or
345 engravers, so by analogy, each plug-in is called @code{engraver}.
347 In the following example, we see how we start out with a plug-in for
348 note heads, the @code{Note_heads_engraver}.
350 @lilypond[quote,raggedright]
351 \include "engraver-example.lyinc"
358 \remove "Stem_engraver"
359 \remove "Phrasing_slur_engraver"
360 \remove "Slur_engraver"
361 \remove "Script_engraver"
362 \remove "Beam_engraver"
363 \remove "Auto_beam_engraver"
367 \remove "Accidental_engraver"
368 \remove "Key_engraver"
369 \remove "Clef_engraver"
370 \remove "Bar_engraver"
371 \remove "Time_signature_engraver"
372 \remove "Staff_symbol_engraver"
373 \consists "Pitch_squash_engraver"
380 Then a @code{Staff_symbol_engraver} adds the staff
382 @lilypond[quote,raggedright]
383 \include "engraver-example.lyinc"
390 \remove "Stem_engraver"
391 \remove "Phrasing_slur_engraver"
392 \remove "Slur_engraver"
393 \remove "Script_engraver"
394 \remove "Beam_engraver"
395 \remove "Auto_beam_engraver"
399 \remove "Accidental_engraver"
400 \remove "Key_engraver"
401 \remove "Clef_engraver"
402 \remove "Bar_engraver"
403 \consists "Pitch_squash_engraver"
404 \remove "Time_signature_engraver"
411 the @code{Clef_engraver} defines a reference point for the staff
413 @lilypond[quote,raggedright]
414 \include "engraver-example.lyinc"
421 \remove "Stem_engraver"
422 \remove "Phrasing_slur_engraver"
423 \remove "Slur_engraver"
424 \remove "Script_engraver"
425 \remove "Beam_engraver"
426 \remove "Auto_beam_engraver"
430 \remove "Accidental_engraver"
431 \remove "Key_engraver"
432 \remove "Bar_engraver"
433 \remove "Time_signature_engraver"
440 and the @code{Stem_engraver} adds stems.
442 @lilypond[quote,raggedright]
443 \include "engraver-example.lyinc"
450 \remove "Phrasing_slur_engraver"
451 \remove "Slur_engraver"
452 \remove "Script_engraver"
453 \remove "Beam_engraver"
454 \remove "Auto_beam_engraver"
458 \remove "Accidental_engraver"
459 \remove "Key_engraver"
460 \remove "Bar_engraver"
461 \remove "Time_signature_engraver"
467 The @code{Stem_engraver} is notified of any note head coming along.
468 Every time one (or more, for a chord) note head is seen, a stem
469 object is created and connected to the note head.
470 By adding engravers for beams, slurs, accents, accidentals, bar lines,
471 time signature, and key signature, we get a complete piece of
474 @lilypond[quote,raggedright]
475 \include "engraver-example.lyinc"
479 This system works well for monophonic music, but what about
480 polyphony? In polyphonic notation, many voices can share a staff.
482 @lilypond[quote,raggedright]
483 \include "engraver-example.lyinc"
484 \score { \context Staff << \topVoice \\ \botVoice >> }
487 In this situation, the accidentals and staff are shared, but the
488 stems, slurs, beams, etc., are private to each voice. Hence, engravers
489 should be grouped. The engravers for note heads, stems, slurs, etc., go
490 into a group called `Voice context,' while the engravers for key,
491 accidental, bar, etc., go into a group called `Staff context.' In the
492 case of polyphony, a single Staff context contains more than one Voice
493 context. In polyphonic notation, many voices can share a staff.
494 Similarly, more Staff contexts can be put into a single Score context.
496 @lilypond[quote,raggedright]
497 \include "engraver-example.lyinc"
500 \new Staff << \topVoice \\ \botVoice >>
501 \new Staff << \pah \\ \hoom >>
506 @node Music representation
507 @section Music representation
509 Ideally, the input format for any high-level formatting system is an
510 abstract description of the content. In this case, that would be the
511 music itself. This poses a formidable problem: how can we define what
512 music really is? Instead of trying to find an answer, we have reversed
513 the question. We write a program capable of producing sheet music,
514 and adjust the format to be as lean as possible. When the format can
515 no longer be trimmed down, by definition we are left with content
516 itself. Our program serves as a formal definition of a music
519 The syntax is also the user-interface for LilyPond, hence it is easy
527 a quarter note C1 (middle C) and an eighth note D1 (D above middle C)
529 @lilypond[quote,fragment]
533 On a microscopic scale, such syntax is easy to use. On a larger
534 scale, syntax also needs structure. How else can you enter complex
535 pieces like symphonies and operas? The structure is formed by the
536 concept of music expressions: by combining small fragments of music
537 into larger ones, more complex music can be expressed. For example
539 @lilypond[quote,verbatim,fragment,relative=1]
544 Chords can be constructed with < and > enclosing the notes
550 @lilypond[quote,fragment,relative=1]
551 \new Voice { <c d e>4 }
555 This expression is put in sequence by enclosing it in curly braces
556 @code{@{@tie{}@dots{}@tie{}@}}
562 @lilypond[quote,relative=1]
563 \new Voice { <c d e>4 f4 }
567 The above is an expression also, and thus it may be combined again with
568 another simultaneous expression (a half note) using <<, @code{\\}, and >>
571 << g2 \\ @{ <c d e>4 f4 @} >>
574 @lilypond[quote,fragment,relative=2]
575 \new Voice { << g2 \\ { <c d e>4 f4 } >> }
578 Such recursive structures can be specified neatly and formally in a
579 context-free grammar. The parsing code is also generated from this
580 grammar. In other words, the syntax of LilyPond is clearly and
581 unambiguously defined.
583 User-interfaces and syntax are what people see and deal with
584 most. They are partly a matter of taste, and also subject of much
585 discussion. Although discussions on taste do have their merit, they
586 are not very productive. In the larger picture of LilyPond, the
587 importance of input syntax is small: inventing neat syntax is easy,
588 writing decent formatting code is much harder. This is also
589 illustrated by the line-counts for the respective components: parsing
590 and representation take up less than 10% of the code.
593 @node Example applications
594 @section Example applications
596 We have written LilyPond as an experiment of how to condense the art
597 of music engraving into a computer program. Thanks to all that hard
598 work, the program can now be used to perform useful tasks. The
599 simplest application is printing notes.
601 @lilypond[quote,relative=1]
602 \time 2/4 c4 c g'4 g a4 a g2
606 By adding chord names and lyrics we obtain a lead sheet.
608 @lilypond[quote,raggedright]
611 \context ChordNames \chords { c2 c f2 c }
612 \new Staff \notes \relative c' { \time 2/4 c4 c g'4 g a4 a g2 }
613 \context Lyrics \lyrics { twin4 kle twin kle lit tle star2 }
618 Polyphonic notation and piano music can also be printed. The following
619 example combines some more exotic constructs.
621 @lilypondfile[quote,raggedright]{screech-boink.ly}
623 The fragments shown above have all been written by hand, but that is
624 not a requirement. Since the formatting engine is mostly automatic, it
625 can serve as an output means for other programs that manipulate
626 music. For example, it can also be used to convert databases of
627 musical fragments to images for use on websites and multimedia
630 This manual also shows an application: the input format is text, and
631 can therefore be easily embedded in other text-based formats such as
632 La@TeX{}, HTML, or in the case of this manual, Texinfo. By means of a
633 special program, the input fragments can be replaced by music images
634 in the resulting PostScript or HTML output files. This makes it easy
635 to mix music and text in documents.
639 @node About this manual
640 @section About this manual
642 The manual is divided into the following chapters:
649 @emph{@ref{Tutorial}}
650 gives a gentle introduction to typesetting music.
651 First time users should start here.
657 @emph{@ref{Notation manual}}
658 discusses topics grouped by notation construct. Once you master the
659 basics, this is the place to look up details.
665 @emph{@ref{Changing defaults}}
666 explains how to fine tune layout.
672 @emph{@ref{Invoking LilyPond}} shows how to run LilyPond and its helper
679 @emph{@ref{lilypond-book manual}}
680 explains the details behind creating documents with in-line music
681 examples (like this manual).
687 @emph{@ref{Converting from other formats}}
688 explains how to run the conversion programs. These programs
689 are supplied with the LilyPond package, and convert a variety of music
690 formats to the @code{.ly} format. In addition, this section explains
691 how to upgrade input files from previous versions of LilyPond.
697 @emph{@ref{Literature list}}
698 contains a set of useful reference books, for those who wish to know
699 more on notation and engraving.
702 Once you are an experienced user, you can use the manual as reference:
703 there is an extensive index@footnote{If you are looking for something,
704 and you cannot find it in the manual, that is considered a bug. In
705 that case, please file a bug report.}, but the document is also
711 @uref{../lilypond.html, a big HTML page}
713 which can be searched easily using the search facility of a web
715 @cindex search in manual
716 @cindex using the manual
719 @c add/integrate glossary, put in list above
720 If you are not familiar with music notation or music terminology
721 (especially if you are a non-native English speaker), it is advisable
722 to consult the glossary as well. The glossary explains musical terms,
723 and includes translations to various languages. It is a
725 @uref{../music-glossary.html,separate document}.
728 separate document, available in HTML and PDF.
733 @cindex foreign languages
737 This manual is not complete without a number of other documents. They
738 are not available in print, but should be included with the
739 documentation package for your platform:
745 (available @uref{../lilypond-internals/lilypond-internals.html,here})
748 The program reference is a set of heavily cross linked HTML pages,
749 which document the nit-gritty details of each and every LilyPond
750 class, object, and function. It is produced directly from the
751 formatting definitions used.
753 Almost all formatting functionality that is used internally, is
754 available directly to the user. For example, all variables that
755 control thickness values, distances, etc., can be changed in input
756 files. There are a huge number of formatting options, and all of them
757 are described in the generated documentation. Each section of the
758 notation manual has a @b{See also} subsection, which refers to the
759 the generated documentation. In the HTML document, these subsections
760 have clickable links.
765 (available @uref{../../../../input/template/out-www/collated-files.html,here})
768 After you have gone through the tutorial, you should be able to write
769 input files. In practice, writing files from scratch turns out to be
770 intimidating. To give you a head start, we have collected a number of
771 often-used formats in example files; simply copy the template and add
772 notes in the appropriate places.
775 Various input examples
777 (available @uref{../../../../input/test/out-www/collated-files.html,here})
781 This collection of files shows various tips and tricks, and is
782 available as a big HTML document, with pictures and explanatory texts
788 (available @uref{../../../../input/regression/out-www/collated-files.html,here})
791 This collection of files tests each notation and engraving feature of
792 LilyPond in one file. The collection is primarily there to help us
793 debug problems, but it can be instructive to see how we exercise the
794 program. The format is similar to the the tips and tricks document.
798 In all HTML documents that have music fragments embedded, the LilyPond
799 input that was used to produce that image can be viewed by clicking
802 The location of the documentation files that are mentioned here can
803 vary from system to system. On occasion, this manual refers to
804 initialization and example files. Throughout this manual, we refer to
805 input files relative to the top-directory of the source archive. For
806 example, @file{input/test/bla.ly} may refer to the file
807 @file{lilypond-1.7.19/input/test/bla.ly}. On binary packages for the
808 Unix platform, the documentation and examples can typically be found
809 somewhere below @file{/usr/share/doc/lilypond/}. Initialization files,
810 for example @file{scm/lily.scm}, or @file{ly/engraver-init.ly}, are
811 usually found in the directory @file{/usr/share/lilypond/}.
813 @cindex adjusting output
816 @cindex lilypond-internals
817 @cindex internal documentation
819 @cindex extending lilypond
823 Finally, this and all other manuals, are available online both as PDF
824 files and HTML from the web site, which can be found at
825 @uref{http://www.lilypond.org/}.