1 @c -*- coding: utf-8; mode: texinfo; -*-
4 Translation of GIT committish: FILL-IN-HEAD-COMMITTISH
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14 @chapter Music engraving
16 This essay describes why LilyPond was created and how it can produce
17 such beautiful sheet music.
20 @c remove 3mm eps bounding box left padding for Sarabande (This will
21 @c require adding a new snippet option to lilypond-book.py
22 @c check formatting of HTML output
25 * The LilyPond story::
27 * Automated engraving::
29 * Putting LilyPond to work::
30 * Engraved examples (BWV 861)::
33 @node The LilyPond story
34 @section The LilyPond story
36 Long before LilyPond had been used to engrave beautiful performance
37 scores, before it could create university course notes or even simple
38 melodies, before there was a community of users around the world or even
39 an essay on music engraving, LilyPond began with a question:
42 Why does most computer output fail to achieve the beauty and balance of
43 a hand-engraved score?
47 Some of the answers can be found by examining the two scores
52 on the following pages.
54 The first score is a beautiful hand-engraved score from 1950 and the
55 second is a modern, computer-engraved edition.
60 Bärenreiter BA 320, @copyright{}1950:
62 @sourceimage{baer-suite1-fullpage,,,png}
67 Henle no. 666, @copyright{}2000:
69 @sourceimage{henle-suite1-fullpage,,,png}
73 The notes here are identical, taken from Bach's first Suite for solo
74 cello, but the appearance is different, especially if you print them out
75 and view them from a distance.
77 (The PDF version of this manual has high-resolution images suitable for
80 Try reading or playing from each of the scores and you will find that
81 the hand-engraved score is more enjoyable to use. It has flowing lines
82 and movement, and it feels like a living, breathing piece of music,
83 while the newer edition seems cold and mechanical.
85 It is hard to immediately see what makes the difference with the newer
86 edition. Everything looks neat and tiny, possibly even @qq{better}
87 because it looks more computerized and uniform. This really puzzled us
88 for quite a while. We wanted to improve computer notation, but we first
89 had to figure out what was wrong with it.
91 The answer lies in the precise, mathematical uniformity of the newer
92 edition. Find the bar line in the middle of each line: in the
93 hand-engraved score the position of these bar lines has some
94 natural variation, while in the newer version they line up almost
95 perfectly. This is shown in these simplified page layout diagrams,
96 traced from the hand-engraved (left) and computer-generated music
101 @sourceimage{pdf/page-layout-comparison,,,}
104 @sourceimage{page-layout-comparison,,,png}
109 In the computer-generated output, even the individual note heads are
110 aligned in vertical columns, making the contour of the melody disappear
111 into a rigid grid of musical markings.
113 There are other differences as well: in the hand-engraved edition the
114 vertical lines are all stronger, the slurs lie closer to the note heads,
115 and there is more variety in the slopes of the beams. Although such
116 details may seem like nitpicking, the result is a score that is easier
117 to read. In the computer-generated output, each line is nearly identical
118 and if the musician looks away for a moment she will be lost on the
121 LilyPond was designed to solve the problems we found in existing
122 software and to create beautiful music that mimics the finest
123 hand-engraved scores.
128 Bärenreiter BA 320, @copyright{}1950:
130 @sourceimage{baer-suite1-fullpage-hires,16cm,,}
133 Henle no. 666, @copyright{}2000:
135 @sourceimage{henle-suite1-fullpage-hires,16cm,,}
139 @node Engraving details
140 @section Engraving details
143 @cindex typography, music
144 @cindex music typography
145 @cindex plate engraving
146 @cindex music engraving
148 The art of music typography is called @emph{(plate) engraving}, a term
149 that derives from the manual process of music printing@footnote{Early
150 European printers explored several processes, including hand-carved
151 wooden blocks, movable type, and engraved sheets of thin metal.
152 Typesetting had the advantage of being more easily corrected and
153 facilitating the inclusion of text and lyrics, but only engraving
154 offered the ability to do unimpeded layout and unanticipated notation.
155 In the end, hand-engraved scores became the standard for all printed
156 music, with the exception of some hymnals and songbooks where
157 typesetting was justified by its ease and economy, even into the
158 twentieth century.}. Just a few decades ago, sheet music was made by
159 cutting and stamping the music into a zinc or pewter plate in mirror
160 image. The plate would be inked, and the depressions caused by the
161 cutting and stamping would hold ink. An image was formed by pressing
162 paper to the plate. The stamping and cutting was done completely by hand
163 and making a correction was cumbersome, so the engraving had to be
164 nearly perfect in one go. Engraving was a highly specialized skill; a
165 craftsman had to complete around five years of training before earning
166 the title of master engraver, and another five years of experience were
167 necessary to become truly skilled.
171 @sourceimage{hader-slaan,,7cm,}
174 @sourceimage{hader-slaan,,,jpg}
178 LilyPond is inspired by traditional manual engravings published by
179 European music publishers in and towards the end of the first half of
180 the twentieth century, including Bärenreiter, Duhem, Durand,
181 Hofmeister, Peters, and Schott. This is sometimes regarded as the peak
182 of traditional musical engraving practice. As we have studied these
183 editions we have learned a great deal about what goes into a
184 well-engraved score, and the aspects that we wanted to imitate in
187 @c Now all newly printed music is produced with computers. This has
188 @c obvious advantages: prints are cheaper to make, editorial work can be
189 @c delivered by email, and the original data can be easily stored.
190 @c Unfortunately, computer-generated scores rarely match the quality of
191 @c hand-engraved scores. Instead, computer printouts have a bland,
192 @c mechanical look, which makes them unpleasant to play from.
199 * Why work so hard?::
203 @unnumberedsubsec Music fonts
205 The images below illustrate some differences between traditional
206 engraving and typical computer output. The left picture shows a scan of
207 a flat symbol from a hand-engraved Bärenreiter edition, while the right
208 picture depicts a symbol from an edition of the same music published in
209 2000. Although both images are printed in the same shade of ink, the
210 earlier version looks darker: the staff lines are heavier, and the
211 Bärenreiter flat has a bold, almost voluptuous rounded look. The right
212 scan, on the other hand, has thinner lines and a straight layout with
215 @multitable @columnfractions .25 .25 .25 .25
219 @sourceimage{baer-flat-gray,,4cm,}
222 @sourceimage{baer-flat-gray,,,png}
227 @sourceimage{henle-flat-gray,,4cm,}
230 @sourceimage{henle-flat-gray,,,png}
235 @sourceimage{henle-flat-bw,,,png}
236 @sourceimage{baer-flat-bw,,,png}
237 @sourceimage{lily-flat-bw,,,png}
248 @cindex musical symbols
253 When we wanted to write a computer program to create music typography,
254 there were no musical fonts freely available that could match the
255 elegance of our favorite scores. Undeterred, we created a font of
256 musical symbols, relying on nice printouts of hand-engraved music. The
257 experience helped develop a typographical taste, and it made us
258 appreciate subtle design details. Without that experience, we would not
259 have realized how ugly the fonts were that we admired at first.
261 Below is a sample of two music fonts: the upper set is the default font
262 in the Sibelius software (the @emph{Opus} font), and the lower set is
263 our own LilyPond font.
267 @sourceimage{pdf/OpusAndFeta,,,}
270 @sourceimage{OpusAndFeta,,,png}
274 The LilyPond symbols are heavier and their weight is more consistent,
275 which makes them easier to read. Fine endings, such as the ones on the
276 sides of the quarter rest, should not end in sharp points, but rather
277 in rounded shapes. This is because sharp corners of the punching dies
278 are fragile and quickly wear out when stamping in metal. Taken together,
279 the blackness of the font must be carefully tuned together with the
280 thickness of lines, beams and slurs to give a strong yet balanced
283 Also, notice that our half-note head is not elliptic but slightly diamond
284 shaped. The vertical stem of a flat symbol is slightly brushed, becoming
285 wider at the top. The sharp and the natural are easier to distinguish
286 from a distance because their angled lines have different slopes and the
287 vertical strokes are heavier.
289 @node Optical spacing
290 @unnumberedsubsec Optical spacing
292 In spacing, the distribution of space should reflect the durations
293 between notes. However, as we saw in the Bach Suite above, many modern
294 scores adhere to the durations with mathematical precision, which leads
295 to poor results. In the next example a motive is printed twice: the
296 first time using exact mathematical spacing, and the second with
297 corrections. Which do you prefer?
299 @cindex optical spacing
320 \override NoteSpacing #'stem-spacing-correction = #0.0
321 \override NoteSpacing #'same-direction-correction = #0.0
322 \override StaffSpacing #'stem-spacing-correction = #0.0
348 \override NoteSpacing #'stem-spacing-correction = #0.6
354 @cindex regular rhythms
355 @cindex regular spacing
356 @cindex spacing, regular
358 Each bar in the fragment only uses notes that are played in a constant
359 rhythm. The spacing should reflect that. Unfortunately, the eye deceives
360 us a little; not only does it notice the distance between note heads, it
361 also takes into account the distance between consecutive stems. As a
362 result, the notes of an up-stem/@/down-stem combination should be put
363 farther apart, and the notes of a down-stem/@/up-stem combination should
364 be put closer together, all depending on the combined vertical positions
365 of the notes. The lower two measures are printed with this correction,
366 the upper two measures, however, form down-stem/@/up-stem clumps of
367 notes. A master engraver would adjust the spacing as needed to please
370 The spacing algorithms in LilyPond even take the barlines into account,
371 which is why the final up-stem in the properly spaced example has been
372 given a little more space before the barline to keep it from looking
373 crowded. A down-stem would not need this adjustment.
376 @unnumberedsubsec Ledger lines
381 Ledger lines present a typographical challenge: they make it more
382 difficult to space musical symbols close together and they must be clear
383 enough to identify the pitch at a glance. In the example below, we see
384 that ledger lines should be thicker than normal staff lines and that an
385 expert engraver will shorten a ledger line to allow closer spacing with
386 accidentals. We have included this feature in LilyPond's engraving.
388 @multitable @columnfractions .25 .25 .25 .25
392 @sourceimage{baer-ledger,3cm,,}
395 @sourceimage{baer-ledger,,,png}
401 @sourceimage{lily-ledger,3cm,,}
404 @sourceimage{lily-ledger,,,png}
411 @unnumberedsubsec Optical sizing
413 Music may need to be printed in a range of sizes. Originally, this was
414 accomplished by creating punching dies in each of the required sizes,
415 which meant that each die was designed to look its best at that size.
416 With the advent of digital fonts, a single outline can be mathematically
417 scaled to any size, which is very convenient, but at the smaller sizes
418 the glyphs will appear very light.
420 In LilyPond, we have created fonts in a range of weights, corresponding
421 to a range of music sizes. This is a LilyPond engraving at staff size
426 @sourceimage{pdf/size26,,23mm,}
429 @sourceimage{size26,,,png}
434 and this is the same engraving set at staff size 11, then
435 magnified by 236% to print at the same size as the previous example:
439 @sourceimage{pdf/size11,,23mm,}
442 @sourceimage{size11,,,png}
447 At smaller sizes, LilyPond uses proportionally heavier lines so the
448 music will still read well.
451 This also allows staves of different sizes to coexist peacefully when
452 used together on the same page:
454 @c TODO: are the stems in this example the right thickness? How should
455 @c line weights be scaled for small staves?
457 @c Grieg's Violin Sonata Op. 45
458 @lilypond[indent=1.5cm]
468 \override StaffSymbol #'staff-space = #(magstep -4)
469 \override StaffSymbol #'thickness = #(magstep -3)
473 \set Staff.instrumentName = #"Violin"
474 c8.(\f^> b16 c d) ees8.(^> d16 c b)
475 g8.(^> b16 c ees) g8-.^> r r
479 \set PianoStaff.instrumentName = #"Piano"
480 \new Staff \relative c' {
483 s4. s8 r8 r16 <c f aes c>
484 <c f aes c>4.^> <c ees g>8 r r
486 \new Staff \relative c {
491 \once \override DynamicText #'X-offset = #-3
493 <ees g c>4.~ <ees g c>8
496 <c g c,>4.~ <c g c,>8
499 r8 r16 <f, c' aes'>16
500 <f c' aes'>4.-> <c' g'>8 r r
508 @node Why work so hard?
509 @unnumberedsubsec Why work so hard?
511 Musicians are usually more absorbed with performing than with studying
512 the looks of a piece of music, so nitpicking typographical details may
513 seem academic. But it is not. Sheet music is performance material:
514 everything is done to aid the musician in letting her perform better,
515 and anything that is unclear or unpleasant to read is a hindrance.
517 Traditionally engraved music uses bold symbols on heavy staff to create
518 a strong, well-balanced look that stands out well when the music is far
519 away from the reader: for example, if it is on a music stand. A careful
520 distribution of white space allows music to be set very tightly without
521 crowding symbols together. The result minimizes the number of page
522 turns, which is a great advantage.
524 This is a common characteristic of typography. Layout should be pretty,
525 not only for its own sake, but especially because it helps the reader in
526 his task. For sheet music this is of double importance because musicians
527 have a limited amount of attention. The less attention they need for
528 reading, the more they can focus on playing the music. In other words,
529 better typography translates to better performances.
531 These examples demonstrate that music typography is an art that is
532 subtle and complex, and that producing it requires considerable
533 expertise, which musicians usually do not have. LilyPond is our
534 effort to bring the graphical excellence of hand-engraved music to
535 the computer age, and make it available to normal musicians. We
536 have tuned our algorithms, font-designs, and program settings to
537 produce prints that match the quality of the old editions we love
538 to see and love to play from.
541 @node Automated engraving
542 @section Automated engraving
544 @cindex engraving, automated
545 @cindex automated engraving
547 Here we describe what is required to create software that can mimic the
548 layout of engraved scores: a method of describing good layouts to the
549 computer and a lot of detailed comparisons with real engravings.
553 * Improvement by benchmarking::
554 * Getting things right::
557 @node Beauty contests
558 @unnumberedsubsec Beauty contests
560 How do we actually make formatting decisions? In other words, which
561 of the three configurations should we choose for the following slur?
566 \once \override Slur #'positions = #'(1.5 . 1)
567 e8[( f] g[ a b d,)] r4
568 \once \override Slur #'positions = #'(2 . 3)
569 e8[( f] g[ a b d,)] r4
570 e8[( f] g[ a b d,)] r4
574 There are a few books on the art of music engraving
575 available. Unfortunately, they contain simple rules of thumb and some
576 examples. Such rules can be instructive, but they are a far cry from
577 an algorithm that we could readily implement in a computer. Following
578 the instructions from literature leads to algorithms with lots of
579 hand-coded exceptions. Doing all this case analysis is a lot of work,
580 and often not all cases are covered completely:
584 @sourceimage{ross-beam-scan,7cm,,}
587 @sourceimage{ross-beam-scan,,,.jpg}
591 (Image source: Ted Ross, @emph{The Art of Music Engraving})
593 Rather than trying to write detailed layout rules for every possible
594 scenario, we only have to describe the objectives well enough that
595 LilyPond can judge the attractiveness of several alternatives. Then,
596 for each possible configuration we compute an ugliness score and we
597 choose the least ugly configuration.
599 For example, here are three possible slur configurations, and LilyPond
600 has given each one a score in @q{ugly points}. The first example gets
601 15.39 points for grazing one of the noteheads:
606 \once \override Slur #'positions = #'(1.5 . 1)
607 e8[(_"15.39" f] g[ a b d,)] r4
612 second one is nicer, but the slur doesn't start or end on the note heads.
613 It gets 1.71 points for the left side and 9.37 points for the right
614 side, plus another 2 points because the slur ascends while the melody
615 descends for a total of 13.08 ugly points:
620 \once \override Slur #'positions = #'(2 . 3)
621 e8[(_"13.08" f] g[ a b d,)] r4
625 The final slur gets 10.04
626 points for the gap on the right and 2 points for the upward slope, but
627 it is the most attractive of the three configurations, so LilyPond
633 e8[(_"12.04" f] g[ a b d,)] r4
637 This technique is quite general, and is used to make optimal decisions
638 for beam configurations, ties and dots in chords, line breaks, and page
639 breaks. The results of these decisions can be judged by comparison to
642 @node Improvement by benchmarking
643 @unnumberedsubsec Improvement by benchmarking
645 LilyPond's output has improved gradually over time, and it continues to
646 improve by comparing its output to hand-engraved scores.
648 For example, here is one line of a benchmark piece from a
649 hand-engraved edition (Bärenreiter BA320):
652 @sourceimage{baer-sarabande-hires,16cm,,}
655 @sourceimage{baer-sarabande,,,png}
659 and the same quotation as engraved by a very old version of LilyPond
660 (version 1.4, May 2001):
663 @sourceimage{pdf/lily14-sarabande,16cm,,}
666 @sourceimage{lily14-sarabande,,,png}
669 @noindent The LilyPond 1.4 output is certainly readable, but close
670 comparison with the hand-engraved score showed a lot of errors in the
674 @sourceimage{lily14-sarabande-annotated-hires,16cm,,}
677 @sourceimage{lily14-sarabande-annotated,,,png}
681 @item there is too much space before the time signature
682 @item the stems of the beamed notes are too long
683 @item the second and fourth measures are too narrow
684 @item the slur is awkward-looking
685 @item the trill marks are too big
686 @item the stems are too thin
690 (There were also two missing note heads, several missing editorial
691 annotations, and an incorrect pitch!)
693 By adjusting the layout rules and font design, the output has improved
694 considerably. Compare the same reference score and the output
695 from the current version of LilyPond (@version{}):
698 @sourceimage{baer-sarabande-hires,16cm,,}
701 @sourceimage{baer-sarabande,,,png}
704 @lilypond[staffsize=17.5,line-width=15.9\cm]
709 \mergeDifferentlyDottedOn
711 { \slurDashed d8.-\flageolet( e16) e4.-\trill( d16 e) }
716 <f' a, d,>4. e8( d c)
718 bes8 g' f e16( f g_1 a_2 bes_3 d,_2)
720 cis4.-\trill b8_3( a g)
722 { \slurDashed d'8.( e16) e4.-\trill( d16 e) }
730 The current output is not a clone of the reference edition, but it is
731 much closer to publication quality that the earlier output.
733 @node Getting things right
734 @unnumberedsubsec Getting things right
736 We can also measure LilyPond's ability to make music engraving decisions
737 automatically by comparing LilyPond's output to the output of a
738 commercial software product. In this case we have chosen Finale 2008,
739 which is one of the most popular commercial score writers, particularly
740 in North America. Sibelius is their major rival and they appear to be
741 especially strong in the European market.
743 For our comparison we selected Bach's Fugue in G minor from the
744 Well-Tempered Clavier, Book I, BWV 861, whose opening subject is
751 r8 a16 bes c8 bes16 a bes8
757 We made our comparison by engraving the last seven measures of the piece
758 (28--34) in Finale and LilyPond. This is the point in the piece where
759 the subject returns in a three-part stretto and leads into the closing
760 section. In the Finale version, we have resisted the temptation to make
761 any adjustments to the default output because we are trying to show the
762 things that each software package gets right without assistance. The
763 only major edits that we made were adjusting the page size to match this
764 essay and forcing the music onto two systems to make the comparison
765 easier. By default Finale would have engraved two systems of three
766 measures each and a final, full-width system containing a single
769 Many of the differences between the two engravings are visible in
770 measures 28--29, as shown here with Finale first and LilyPond second:
773 @sourceimage{pdf/bwv861mm28-29,14cm,,}
776 @sourceimage{bwv861mm28-29,,,png}
779 @lilypond[staffsize=19.5,line-width=14\cm]
780 global = { \key g \minor }
782 partI = \relative c' {
784 fis8 d' ees g, fis4 g
785 r8 a16 bes c8 bes16 a d8 r r4
788 partII = \relative c' {
790 d4 r4 r8 d'16 c bes8 c16 d
794 partIII = \relative c' {
796 r2 r8 d ees g, fis4 g r8 a16 bes c8 bes16 a
799 partIV = \relative c {
807 % \set Score.barNumberVisibility = #all-bar-numbers-visible
809 \set Score.currentBarNumber = #28
814 \new Voice = "voiceI" { \partI }
815 \new Voice = "voiceII" { \partII }
821 \new Voice = "voiceIII" { \partIII }
822 \new Voice = "voiceIV" { \partIV }
829 \remove "Time_signature_engraver"
833 \override StaffGrouper #'staff-staff-spacing #'padding = #1
839 Some shortcomings in the unedited Finale output include:
841 @item Most of the beams extend too far off the staff. A beam that points
842 towards the center of the staff should have a length of about one
843 octave, but engravers shorten this when the beam points away from the
844 staff in multi-voice music. The Finale beaming can be easily improved
845 with their Patterson Beams plug-in, but we elected to skip that step for
847 @item Finale doesn't adjust the positions of interlocking note heads,
848 which makes the music extremely difficult to read when the upper and
849 lower voices exchange positions temporarily:
852 collide = \once \override NoteColumn #'force-hshift = #0
856 \new Voice = "sample" \relative c''{
859 { \voiceOne g4 \collide g4 }
860 \new Voice { \voiceTwo bes \collide bes }
863 \new Lyrics \lyricsto "sample" \lyricmode { "good " " bad" }
868 @item Finale has placed all of the rests at fixed heights on the staff.
869 The user is free to adjust them as needed, but the software makes no
870 attempt to consider the content of the other voice. As luck would have
871 it, there are no true collisions between notes and rests in this example,
872 but that has more to do with the positions of the notes than the rest.
873 In other words, Bach deserves more credit for avoiding a complete
874 collision than Finale does.
878 This example is not intended to suggest that Finale cannot be used to
879 produce publication-quality output. On the contrary, in the hands of a
880 skilled user it can and does, but it requires skill and time. One of the
881 fundamental differences between LilyPond and commercial scorewriters is
882 that LilyPond hopes to reduce the amount of human intervention to an
883 absolute minimum, while other packages try to provide an attractive
884 interface in which to make these types of edits.
886 One particularly glaring omission we found from Finale is a missing flat
891 @sourceimage{pdf/bwv861mm33-34-annotate,7.93cm,,}
894 @sourceimage{bwv861mm33-34-annotate,,,png}
899 The flat symbol is required to cancel out the natural in the same
900 measure, but Finale misses it because it occurred in a different voice.
901 So in addition to running a beaming plug-in and checking the spacing on
902 the noteheads and rests, the user must also check each measure for
903 cross-voice accidentals to avoid interrupting a rehearsal over an
906 If you are interested in examining these examples in more detail, the
907 full seven-measure excerpt can be found at the end of this essay along
908 with four different published engravings. Close examination reveals that
909 there is some acceptable variation among the hand-engravings, but that
910 LilyPond compares reasonably well to that acceptable range. There are
911 still some shortcomings in the LilyPond output, for example, it appears
912 a bit too aggressive in shortening some of the stems, so there is room
913 for further development and fine-tuning.
915 Of course, typography relies on human judgment of appearance, so people
916 cannot be replaced completely. However, much of the dull work can be
917 automated. If LilyPond solves most of the common situations correctly,
918 this will be a huge improvement over existing software. Over the course
919 of years, the software can be refined to do more and more things
920 automatically, so manual overrides are less and less necessary. Where
921 manual adjustments are needed, LilyPond's structure has been designed
922 with that flexibility in mind.
924 @node Building software
925 @section Building software
927 This section describes some of the programming decisions that we made
928 when designing LilyPond.
931 * Music representation::
932 * What symbols to engrave?::
933 * Flexible architecture::
937 @node Music representation
938 @unnumberedsubsec Music representation
941 @cindex recursive structures
943 Ideally, the input format for any high-level formatting system is
944 an abstract description of the content. In this case, that would
945 be the music itself. This poses a formidable problem: how can we
946 define what music really is? Instead of trying to find an answer,
947 we have reversed the question. We write a program capable of
948 producing sheet music, and adjust the format to be as lean as
949 possible. When the format can no longer be trimmed down, by
950 definition we are left with content itself. Our program serves as
951 a formal definition of a music document.
953 The syntax is also the user-interface for LilyPond, hence it is
963 to create a quarter note on middle C (C1) and an eighth note on
964 the D above middle C (D1).
972 On a microscopic scale, such syntax is easy to use. On a larger
973 scale, syntax also needs structure. How else can you enter
974 complex pieces like symphonies and operas? The structure is
975 formed by the concept of music expressions: by combining small
976 fragments of music into larger ones, more complex music can be
977 expressed. For example
979 @lilypond[quote,verbatim,fragment,relative=1]
984 Simultaneous notes can be constructed by enclosing them with
985 @code{<<} and @code{>>}:
991 @lilypond[quote,fragment,relative=1]
992 \new Voice { <<c4 d4 e>> }
996 This expression is put in sequence by enclosing it in curly braces
997 @code{@{@tie{}@dots{}@tie{}@}}:
1000 @{ f4 <<c4 d4 e4>> @}
1003 @lilypond[quote,relative=1,fragment]
1008 The above is also an expression, and so it may be combined again
1009 with another simultaneous expression (a half note) using
1010 @code{<<}, @code{\\}, and @code{>>}:
1013 << g2 \\ @{ f4 <<c4 d4 e4>> @} >>
1016 @lilypond[quote,fragment,relative=2]
1017 \new Voice { << g2 \\ { f4 <<c d e>> } >> }
1020 Such recursive structures can be specified neatly and formally in
1021 a context-free grammar. The parsing code is also generated from
1022 this grammar. In other words, the syntax of LilyPond is clearly
1023 and unambiguously defined.
1025 User-interfaces and syntax are what people see and deal with most.
1026 They are partly a matter of taste, and also the subject of much
1027 discussion. Although discussions on taste do have their merit,
1028 they are not very productive. In the larger picture of LilyPond,
1029 the importance of input syntax is small: inventing neat syntax is
1030 easy, while writing decent formatting code is much harder. This
1031 is also illustrated by the line-counts for the respective
1032 components: parsing and representation take up less than 10% of
1035 When designing the structures used in LilyPond, we made some different
1036 decisions than are apparent in other software. Consider the hierarchical
1037 nature of music notation:
1039 @lilypond[quote,fragment]
1041 \new Staff \relative c'' {
1044 d4 g,8 a b c d4 g, g
1046 \new Staff \relative c' {
1054 In this case, there are pitches grouped into chords that belong to
1055 measures, which belong to staves. This resembles a tidy structure of
1060 @sourceimage{pdf/nestedboxes,,4cm,}
1063 @sourceimage{nestedboxes,,,png}
1067 Unfortunately, the structure is tidy because it is based on some
1068 excessively restrictive assumptions. This becomes apparent if we
1069 consider a more complicated musical example:
1075 \remove "Timing_translator"
1076 \remove "Default_bar_line_engraver"
1080 \consists "Timing_translator"
1081 \consists "Default_bar_line_engraver"
1086 \new Staff = "RH" <<
1087 \new Voice = "I" \relative c''' {
1090 \times 6/7 { g8 g g g g g g }
1092 r4 <b,, fis' g bes> r4\fermata
1094 \new Voice = "II" \relative c' {
1099 \change Staff = "LH" \oneVoice
1102 \override Stem #'cross-staff = ##t
1103 \override Stem #'length = #12
1107 \new Staff = "LH" <<
1108 \new Voice = "III" \relative c' {
1118 In this example, staves start and stop at will, voices jump around
1119 between staves, and the staves have different time signatures. Many
1120 software packages would struggle with reproducing this example because
1121 they are built on the nested box structure. With LilyPond, on the other
1122 hand, we have tried to keep the input format and the structure as
1123 flexible as possible.
1125 @node What symbols to engrave?
1126 @unnumberedsubsec What symbols to engrave?
1133 The formatting process decides where to place symbols. However,
1134 this can only be done once it is decided @emph{what} symbols
1135 should be printed -- in other words, what notation to use.
1137 Common music notation is a system of recording music that has
1138 evolved over the past 1000 years. The form that is now in common
1139 use dates from the early Renaissance. Although the basic form
1140 (i.e., note heads on a 5-line staff) has not changed, the details
1141 still evolve to express the innovations of contemporary notation.
1142 Hence, common music notation encompasses some 500 years of music.
1143 Its applications range from monophonic melodies to monstrous
1144 counterpoints for a large orchestra.
1146 How can we get a grip on such a seven-headed beast, and force it
1147 into the confines of a computer program? Our solution is to break
1148 up the problem of notation (as opposed to engraving, i.e.,
1149 typography) into digestible and programmable chunks: every type of
1150 symbol is handled by a separate module, a so-called plug-in. Each
1151 plug-in is completely modular and independent, so each can be
1152 developed and improved separately. Such plug-ins are called
1153 @code{engraver}s, by analogy with craftsmen who translate musical
1154 ideas to graphic symbols.
1156 In the following example, we start out with a plug-in for note
1157 heads, the @code{Note_heads_engraver}.
1159 @lilypond[quote,ragged-right]
1160 \include "engraver-example.ily"
1167 \remove "Stem_engraver"
1168 \remove "Phrasing_slur_engraver"
1169 \remove "Slur_engraver"
1170 \remove "Script_engraver"
1171 \remove "Beam_engraver"
1172 \remove "Auto_beam_engraver"
1176 \remove "Accidental_engraver"
1177 \remove "Key_engraver"
1178 \remove "Clef_engraver"
1179 \remove "Bar_engraver"
1180 \remove "Time_signature_engraver"
1181 \remove "Staff_symbol_engraver"
1182 \consists "Pitch_squash_engraver"
1189 Then a @code{Staff_symbol_engraver} adds the staff,
1191 @lilypond[quote,ragged-right]
1192 \include "engraver-example.ily"
1199 \remove "Stem_engraver"
1200 \remove "Phrasing_slur_engraver"
1201 \remove "Slur_engraver"
1202 \remove "Script_engraver"
1203 \remove "Beam_engraver"
1204 \remove "Auto_beam_engraver"
1208 \remove "Accidental_engraver"
1209 \remove "Key_engraver"
1210 \remove "Clef_engraver"
1211 \remove "Bar_engraver"
1212 \consists "Pitch_squash_engraver"
1213 \remove "Time_signature_engraver"
1220 the @code{Clef_engraver} defines a reference point for the staff,
1222 @lilypond[quote,ragged-right]
1223 \include "engraver-example.ily"
1230 \remove "Stem_engraver"
1231 \remove "Phrasing_slur_engraver"
1232 \remove "Slur_engraver"
1233 \remove "Script_engraver"
1234 \remove "Beam_engraver"
1235 \remove "Auto_beam_engraver"
1239 \remove "Accidental_engraver"
1240 \remove "Key_engraver"
1241 \remove "Bar_engraver"
1242 \remove "Time_signature_engraver"
1249 and the @code{Stem_engraver} adds stems.
1251 @lilypond[quote,ragged-right]
1252 \include "engraver-example.ily"
1259 \remove "Phrasing_slur_engraver"
1260 \remove "Slur_engraver"
1261 \remove "Script_engraver"
1262 \remove "Beam_engraver"
1263 \remove "Auto_beam_engraver"
1267 \remove "Accidental_engraver"
1268 \remove "Key_engraver"
1269 \remove "Bar_engraver"
1270 \remove "Time_signature_engraver"
1277 The @code{Stem_engraver} is notified of any note head coming
1278 along. Every time one (or more, for a chord) note head is seen, a
1279 stem object is created and connected to the note head. By adding
1280 engravers for beams, slurs, accents, accidentals, bar lines, time
1281 signature, and key signature, we get a complete piece of notation.
1283 @lilypond[quote,ragged-right]
1284 \include "engraver-example.ily"
1285 \score { \topVoice }
1289 @cindex engraving multiple voices
1292 This system works well for monophonic music, but what about
1293 polyphony? In polyphonic notation, many voices can share a staff.
1295 @lilypond[quote,ragged-right]
1296 \include "engraver-example.ily"
1297 \new Staff << \topVoice \\ \botVoice >>
1300 In this situation, the accidentals and staff are shared, but the
1301 stems, slurs, beams, etc., are private to each voice. Hence,
1302 engravers should be grouped. The engravers for note heads, stems,
1303 slurs, etc., go into a group called @q{Voice context}, while the
1304 engravers for key, accidental, bar, etc., go into a group called
1305 @q{Staff context}. In the case of polyphony, a single Staff
1306 context contains more than one Voice context. Similarly, multiple
1307 Staff contexts can be put into a single Score context. The Score
1308 context is the top level notation context.
1310 @lilypond[quote,ragged-right]
1311 \include "engraver-example.ily"
1314 \new Staff << \topVoice \\ \botVoice >>
1315 \new Staff << \pah \\ \hoom >>
1321 Internals Reference: @rinternals{Contexts}.
1323 @node Flexible architecture
1324 @unnumberedsubsec Flexible architecture
1326 When we started, we wrote the LilyPond program entirely in the C++
1327 programming language; the program's functionality was set in stone
1328 by the developers. That proved to be unsatisfactory for a number
1333 @item When LilyPond makes mistakes, users need to override
1334 formatting decisions. Therefore, the user must have access to the
1335 formatting engine. Hence, rules and settings cannot be fixed by
1336 us at compile-time but must be accessible for users at run-time.
1338 @item Engraving is a matter of visual judgment, and therefore a
1339 matter of taste. As knowledgeable as we are, users can disagree
1340 with our personal decisions. Therefore, the definitions of
1341 typographical style must also be accessible to the user.
1343 @item Finally, we continually refine the formatting algorithms, so
1344 we need a flexible approach to rules. The C++ language forces a
1345 certain method of grouping rules that cannot readily be applied to
1346 formatting music notation.
1350 @cindex Scheme programming language
1352 These problems have been addressed by integrating an interpreter
1353 for the Scheme programming language and rewriting parts of
1354 LilyPond in Scheme. The current formatting architecture is built
1355 around the notion of graphical objects, described by Scheme
1356 variables and functions. This architecture encompasses formatting
1357 rules, typographical style and individual formatting decisions.
1358 The user has direct access to most of these controls.
1360 Scheme variables control layout decisions. For example, many
1361 graphical objects have a direction variable that encodes the
1362 choice between up and down (or left and right). Here you see two
1363 chords, with accents and arpeggios. In the first chord, the
1364 graphical objects have all directions down (or left). The second
1365 chord has all directions up (right).
1367 @lilypond[quote,ragged-right]
1370 \stemDown <e g b>4_>-\arpeggio
1371 \override Arpeggio #'direction = #RIGHT
1372 \stemUp <e g b>4^>-\arpeggio
1377 \override SpacingSpanner #'spacing-increment = #3
1378 \override TimeSignature #'transparent = ##t
1384 @cindex score formatting
1385 @cindex formatting a score
1386 @cindex formatting rules
1389 The process of formatting a score consists of reading and writing
1390 the variables of graphical objects. Some variables have a preset
1391 value. For example, the thickness of many lines -- a
1392 characteristic of typographical style -- is a variable with a
1393 preset value. You are free to alter this value, giving your score
1394 a different typographical impression.
1396 @lilypond[quote,ragged-right]
1399 c'4-~ c'16 as g f e16 g bes c' des'4
1402 \new Staff \fragment
1404 \override Beam #'beam-thickness = #0.3
1405 \override Stem #'thickness = #0.5
1406 \override Bar #'thickness = #3.6
1407 \override Tie #'thickness = #2.2
1408 \override StaffSymbol #'thickness = #3.0
1409 \override Tie #'extra-offset = #'(0 . 0.3)
1415 Formatting rules are also preset variables: each object has
1416 variables containing procedures. These procedures perform the
1417 actual formatting, and by substituting different ones, we can
1418 change the appearance of objects. In the following example, the
1419 rule governing which note head objects are used to produce the
1420 note head symbol is changed during the music fragment.
1422 @lilypond[quote,ragged-right]
1423 #(set-global-staff-size 30)
1425 #(define (mc-squared grob orig current)
1426 (let* ((interfaces (ly:grob-interfaces grob))
1427 (pos (ly:grob-property grob 'staff-position)))
1428 (if (memq 'note-head-interface interfaces)
1430 (ly:grob-set-property! grob 'stencil
1431 (grob-interpret-markup grob
1432 (make-lower-markup 0.5
1436 ((-2) (make-smaller-markup (make-bold-markup "2")))
1437 (else "bla")))))))))
1439 \new Voice \relative c' {
1441 \set autoBeaming = ##f
1444 \once \override NoteHead #'stencil = #note-head::brew-ez-stencil
1445 \once \override NoteHead #'font-size = #-7
1446 \once \override NoteHead #'font-family = #'sans
1447 \once \override NoteHead #'font-series = #'bold
1449 \once \override NoteHead #'style = #'cross
1451 \applyOutput #'Voice #mc-squared
1454 { d8[ es-( fis^^ g] fis2-) }
1455 \repeat unfold 5 { \applyOutput #'Voice #mc-squared s8 }
1462 @node Putting LilyPond to work
1463 @section Putting LilyPond to work
1465 @cindex simple examples
1466 @cindex examples, simple
1468 We have written LilyPond as an experiment of how to condense the
1469 art of music engraving into a computer program. Thanks to all
1470 that hard work, the program can now be used to perform useful
1471 tasks. The simplest application is printing notes.
1473 @lilypond[quote,relative=1]
1481 By adding chord names and lyrics we obtain a lead sheet.
1483 @lilypond[quote,ragged-right]
1485 \chords { c2 c f2 c }
1491 \addlyrics { twin -- kle twin -- kle lit -- tle star }
1495 Polyphonic notation and piano music can also be printed. The
1496 following example combines some more exotic constructs.
1498 @lilypond[quote,line-width=15.9\cm]
1500 title = "Screech and boink"
1501 subtitle = "Random complex notation"
1502 composer = "Han-Wen Nienhuys"
1506 \context PianoStaff <<
1511 \revert Stem #'direction
1512 \change Staff = down
1513 \set subdivideBeams = ##t
1517 \change Staff = down
1521 \change Staff = down
1525 \set followVoice = ##t
1526 c'''32([ b''16 a''16 gis''16 g''32)]
1528 s4 \times 2/3 { d'16[ f' g'] } as'32[ b''32 e'' d'']
1530 s4 \autoBeamOff d''8.. f''32
1536 \new Staff = "down" {
1539 \set subdivideBeams = ##f
1540 \override Stem #'french-beaming = ##t
1541 \override Beam #'beam-thickness = #0.3
1542 \override Stem #'thickness = #4.0
1543 g'16[ b16 fis16 g16]
1549 \override Staff.Arpeggio #'arpeggio-direction =#down
1550 <cis, e, gis, b, cis>4\arpeggio
1557 tempoWholesPerMinute = #(ly:make-moment 60 8)
1563 \consists Horizontal_bracket_engraver
1569 The fragments shown above have all been written by hand, but that
1570 is not a requirement. Since the formatting engine is mostly
1571 automatic, it can serve as an output means for other programs that
1572 manipulate music. For example, it can also be used to convert
1573 databases of musical fragments to images for use on websites and
1574 multimedia presentations.
1576 This manual also shows an application: the input format is text, and can
1577 therefore be easily embedded in other text-based formats such as
1578 @LaTeX{}, HTML, or in the case of this manual, Texinfo. Using the
1579 @command{lilypond-book} program, included with LilyPond, the input
1580 fragments can be replaced by music images in the resulting PDF or HTML
1581 output files. Another example is the third-party OOoLilyPond extension
1582 for OpenOffice.org, which makes it extremely easy to embed musical
1583 examples in documents.
1585 For more examples of LilyPond in action, full documentation, and the
1586 software itself, see our main website: www.lilypond.org.
1589 @node Engraved examples (BWV 861)
1590 @section Engraved examples (BWV 861)
1592 This section contains four reference engravings and two
1593 software-engraved versions of Bach's Fugue in G minor from the
1594 Well-Tempered Clavier, Book I, BWV 861 (the last seven measures).
1597 Bärenreiter BA5070 (Neue Ausgabe Sämtlicher Werke, Serie V, Band 6.1,
1601 @sourceimage{bwv861-baer,16cm,,}
1604 @sourceimage{bwv861-baer-small,,,png}
1608 Bärenreiter BA5070 (Neue Ausgabe Sämtlicher Werke, Serie V, Band 6.1,
1609 1989), an alternate musical source. Aside from the textual differences,
1610 this demonstrates slight variations in the engraving decisions, even
1611 from the same publisher and edition:
1614 @sourceimage{bwv861-baer-alt,16cm,,}
1617 @sourceimage{bwv861-baer-alt-small,,,png}
1621 Breitkopf & Härtel, edited by Ferruccio Busoni (Wiesbaden, 1894), also
1622 available from the Petrucci Music Library (IMSLP #22081). The editorial
1623 markings (fingerings, articulations, etc.) have been removed for clearer
1624 comparison with the other editions here:
1627 @sourceimage{bwv861-breitkopf,16cm,,}
1630 @sourceimage{bwv861-breitkopf-small,,,png}
1634 Bach-Gesellschaft edition (Leipzig, 1866), available from the Petrucci
1635 Music Library (IMSPL #02221):
1638 @sourceimage{bwv861-gessellschaft,16cm,,}
1641 @sourceimage{bwv861-gessellschaft-small,,,png}
1648 @sourceimage{pdf/bwv861-finale2008a,,,}
1651 @sourceimage{bwv861-finale2008a,,,png}
1656 LilyPond, version @version{}:
1658 @lilypond[staffsize=14.3,line-width=15.9\cm]
1659 global = {\key g \minor}
1661 partI = \relative c' {
1663 fis8 d' ees g, fis4 g
1664 r8 a16 bes c8 bes16 a d8 r r4
1665 r2 r8 d16 ees f8 ees16 d
1666 ees4 ~ ees16 d c bes a4 r8 ees'16 d
1667 c8 d16 ees d8 e16 fis g8 fis16 g a4 ~
1668 a8 d, g f ees d c bes
1669 a2 g\fermata \bar "|."
1672 partII = \relative c' {
1674 d4 r4 r8 d'16 c bes8 c16 d
1675 ees8 d c ees a, r r4
1676 r8 fis16 g a8 g16 fis g2 ~
1678 fis4 g r8 a16 bes c8 bes16 a
1679 bes4. <g b>8 <a c> r <d, g> r
1682 partIII = \relative c' {
1684 r2 r8 d ees g, fis4 g r8 a16 bes c8 bes16 a
1685 bes2 ~ bes8 b16 a g8 a16 b
1689 r8 a16 bes c8 bes16 a b2
1691 partIV = \relative c {
1695 d,8 d'16 c bes8 c16 d ees2 ~
1696 ees8 ees16 d c8 d16 ees fis,8 a16 g fis8 g16 a
1697 d,8 d'16 c bes8 c16 d ees8 c a fis'
1704 % \set Score.barNumberVisibility = #all-bar-numbers-visible
1706 \set Score.currentBarNumber = #28
1709 \new Staff = "RH" <<
1711 \new Voice = "voiceI" { \partI }
1712 \new Voice = "voiceII" { \partII }
1715 \new Staff = "LH" <<
1718 \new Voice = "voiceIII" { \partIII }
1719 \new Voice = "voiceIV" { \partIV }
1726 \remove "Time_signature_engraver"
1730 \override StaffGrouper #'staff-staff-spacing #'padding = #1