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@node Introduction
@chapter Introduction
LilyPond is a program to print sheet music. If you have used notation
programs before, then the way to use this program might be surprising
-at first sight. To print music with lilypond, you have to enter
-musical codes in a file. Then you run LilyPond on the file, and the
-music is produced without any further intervention. For example,
-something like this:
+at first sight: in order to print music you have to enter musical
+codes in a file. Then you run the program on the file, and the music
+is produced without any further intervention. For example, something
+like this:
+
-@lilypond[fragment,verbatim, relative 1, intertext="produces this"]
+@lilypond[fragment,verbatim, relative 1, intertext="produces this:
+
+"]
\key c \minor r8 c16 b c8 g as c16 b c8 d | g,4
@end lilypond
effort to learn the codes and the program you will find that it is
easier than it seems. Entering music can be done quickly, and you
never have to remember how you made the program do something
-complicated: it's all in the input code, and you only have to read the
-file to see how it works. Moreover, when you use LilyPond, you are
-rewarded with very nicely looking output.
+complicated: it is all in the input code, and you only have to read
+the file to see how it works. Moreover, you are rewarded with very
+nicely looking output.
In this chapter, we will explain the reasoning behind this unusual
design, and how this approach affects you as a user.
+
+
@menu
-* Batch processing::
-* Music engraving::
-* Music representation::
-* About this manual::
+* Batch processing::
+* Music engraving::
+* Computerized typography ::
+* Music representation::
+* Example applications::
+* About this manual::
@end menu
@node Batch processing
@cindex Batch
@cindex UNIX
+LilyPond is a @emph{batch} program. To use it, one enters commands in a
+file, and runs the program on that file. The output is produced without
+requiring any further interaction.
+
When we started developing LilyPond, we were still studying at the
university. We were interested in music notation, not as publishers
-or musicians, but as students and scientists. We wanted to figure to
-what extent formatting sheet music could be automated. Back then GUIs
-were not as ubiquitous as they are today, and we were immersed in the
-UNIX operating system, where it is very common to use compilers to
-achieve computing tasks, so our computerized music engraving
+or musicians, but as programmers and scientists. We wanted to figure
+to what extent formatting sheet music could be automated. Back then
+GUIs were not as ubiquitous as they are today, and we were immersed in
+the UNIX operating system, where it is very common to use compilers to
+achieve computing tasks. So, our computerized music engraving
experiment took on the form of a compiler.
+
+@ignore
@cindex free software
@cindex sharing software
that bandwagon, and released LilyPond as free software. That is the
reason that you can get LilyPond at no cost and without any strings
attached.
+@end ignore
@node Music engraving
printing. Only a few decades ago, sheet music was made by cutting and
stamping the music into zinc or pewter plates, mirrored. The plate
would be inked, and the depressions caused by the cutting and stamping
-would hold ink. A positive image was formed by pressing paper to the
+would hold ink. An image was formed by pressing paper to the
plate. Stamping and cutting was completely done by hand. Making
corrections was cumbersome, so engraving had to be done correctly in
one go. As you can imagine this was a highly specialized skill, much
more so than the traditional process of printing books.
-
@cindex craftsmanship
@cindex master
-
-The following fact illustrates that. In the traditional German
-craftsmanship six years of full-time training, more than any other
-craft, were required before a student could call himself a master of
-the art. After that many more years of practical experience were
-needed to become an established music engraver. Even today, with the
-use of high-speed computers and advanced software, music requires lots
-of manual fine tuning before it acceptable to be published.
-
-When we wanted to write a computer program to do create music
-typography, we encountered the first problem: there were no sets of
-musical symbols available: either they were not available freely, or
-they didn't look well to our taste. Not let down, we decided to try
-font design ourselves. We created a font of musical symbols, relying
-on nice printouts of hand-engraved music. It was a good decision to
-design our own font. The experience helped develop a typographical
-taste, and it made us appreciate subtle design details. Without that
-experience, we would not have realized how ugly the fonts were that we
-admired at first.
+In the traditional German craftsmanship six years of full-time
+training, more than any other craft, were required before a student
+could call himself a master of the art. After that many more years of
+practical experience were needed to become an established music
+engraver. Even today, with the use of high-speed computers and
+advanced software, music requires lots of manual fine tuning before it
+is acceptable for publication.
+
+When we wanted to write a computer program to create music typography,
+we encountered the first problem: there were no sets of musical
+symbols available: either they were not available freely, or they did
+not look well to our taste. Not let down, we decided to try font
+design ourselves. We created a font of musical symbols, relying on
+nice printouts of hand-engraved music. The experience helped develop
+a typographical taste, and it made us appreciate subtle design
+details. Without that experience, we would not have realized the
+shortcomings of the fonts were that we admired at first.
@lilypond[noindent]
#(define magfact 3.0)
\score { \notes { as'2 r4 }
\paper {
- linewidth = -1.
+ raggedright = ##t
\translator {
\ScoreContext
AccidentalPlacement \override #'right-padding = #3.0
@cindex blackness
@cindex balance
-The figure above shows a few notable glyphs. For example, the
-half-notehead is not elliptic but slightly diamond shaped. The
-vertical stem of a flat symbol should be slightly brushed,
-i.e. becoming wider at the top. Fine endings, such as the one on the
-bottom of the quarter rest, should not end in sharp points, but rather
-in rounded shapes. Taken together, the blackness of the font must be
+
+The figure above shows a few notable glyphs. For example, the
+vertical stem of the flat symbol should be brushed slightly,
+i.e. becoming wider at the top. the half-notehead is not elliptic but
+slightly diamond shaped. Fine endings, such as the one on the bottom
+of the quarter rest, should not end in sharp points, but rather in
+rounded shapes. Taken together, the blackness of the font must be
carefully tuned together with the thickness of lines, beams and slurs
to give a strong yet balanced overall impression.
Producing a strong and balanced look is the real challenge of music
engraving. It is a recurring theme with many variations. In spacing,
-the balance is in a distribution that reflects the character of the
-music. The spacing should not lead to unnatural clusters of black and
-big gaps with white space. The distances between notes should reflect
-the durations between notes, but adhering with mathematical precision
-to the duration will lead to a poor result. Shown here is an example
-of a motive, printed twice. It is printed using both exact,
-mathematical spacing, and with some corrections. Can you spot which is
-which?
+strength and balance are in layout that is `heavy' enough---without
+big gaps of space--- and without big clusters of black. The
+distribution of space should reflect the character of the music.
+
+Spacing is an example of a subtlety of formatting music. The distances
+between notes should reflect the durations between notes, but adhering
+with mathematical precision to the duration will lead to a poor
+result. Shown here is an example of a motive, printed twice. It is
+printed using exact mathematical spacing, and with some
+corrections. Can you spot which fragment is which?
@cindex optical spacing
c'4 e''4 e'4 b'4 |
\stemDown b'4 e''4 a'4 e''4|
}
- \paper { linewidth = -1. } }
+ \paper { raggedright = ##t } }
@end lilypond
@cindex regular rhythms
played in a constant rhythm. The spacing should reflect
that. Unfortunately, the eye deceives us a little: the eye not only
notices the distance between note heads, but also between consecutive
-stems. The notes of a up-stem/down-stem combination should be put
-farther apart, and the notes of a down-up combination should be put
-closer together, all depending on the combined vertical positions of
-the notes. The first two measures are printed with this correction,
-the last two measures without. The notes in the last two measures form
-downstem/upstems clumps of notes.
+stems. As a result, the notes of a up-stem/down-stem combination
+should be put farther apart, and the notes of a down-up combination
+should be put closer together, all depending on the combined vertical
+positions of the notes. The first two measures are printed with this
+correction, the last two measures without. The notes in the last two
+measures form down-stem/up-stems clumps of notes.
+
+@node Computerized typography
+@section Computerized typography
+
+The example in the previous section is one illustration of how subtle
+music engraving can be is a subtle. Producing good engraving requires
+skill and knowledge.
+
+
+It was our challenge to see if we could put typographical knowledge
+into a computer program. Capturing that knowledge has two aspects:
+first, it has to be acquired. Then, it has to be encoded in
+data-structures and algorithms. As the previous example shows, there
+is a lot of subtlety involved in music engraving, and unfortunately,
+only a small fraction of these tiny details are documented.
+
+One reason for the time that it takes to become a master engraver, is
+that all these details must be learned either from experience or from
+other engravers: as an engraver gets older and wiser, he will be able
+to produce better and more complex pieces. A similar situation is
+present when putting typography into computer programs. It is not
+possible to come up with a final solution for a problem at the first
+try. Instead, we start out with simple solution that might cover 75%
+of the cases, and gradually refine that solution over the course of
+months or years, so that 90 or 95 % of the cases are handled.
+
+This has an important implication for the design of the
+program. During development, almost every piece of formatting code
+must be considered as temporary. When the need arises, is to be
+replaced a solution that will cover even more cases. A clean way to
+accomplish this, is a ``plug-in'' architecture: an architecture where
+new pieces of code can be inserted in the program dynamically. In
+such a program, a new solution can be developed along-side the
+existing code. It can be perfected separately until it is better than
+the existing solution, at which point, the new solution is switched on
+by default, and the old one is removed.
+
+Until that time, users must have a way to deal with imperfections:
+these 25%, 10% or 5% of the cases that are not handled
+automatically. In these cases, a user must be able to override
+formatting decisions. A way to accomplish this, is to store decisions
+in generic variables, and let the user manipulate these variables.
+For example, consider the following fragment of notation.
+
+@lilypond
+\score { \notes {
+ g'4-\f g4
+ }
+\paper { raggedright = ##t }
+ }
+@end lilypond
+
+@noindent
+The position of the forte symbol is slightly awkward, because it is
+next to the low note, whereas dynamics should be below notes in
+general. This may be remedied by inserting extra space between the
+high note and the `f', as shown in this example
+
+@lilypond
+\score { \notes {
+ \once\property Voice. DynamicLineSpanner \override #'padding = #4.0
+ g'4-\f g4
+ }
+\paper { raggedright = ##t }
+ }
+@end lilypond
+
+This was achieved with the input statement
+@example
+ \property Voice. DynamicLineSpanner \override #'padding = #4.0
+@end example
+which increases the amount of space (@code{padding}) between the note
+and the dynamic symbol to 4.0 (which is measured in staff space, so
+4.0 equals the height of a staff).
+
+Both design aspects, a plug-in architecture, and formatting variables,
+are built on top of GUILE, an interpreter for the programming language
+Scheme, which is a member of the LISP family. Variables are stored as
+Scheme objects, and attached to graphical objects such as note heads
+and stems. The variables are a means to adjust formatting details in
+individual cases, but they are used in a more general manner.
+
+Consider the case of a publisher that is not satisfied with the in the
+default layout, and wants heavier stems. Normally, they are @code{1.3}
+times the thickness of staff lines, but suppose that their editions
+require them to be twice the thickness of the staff lines. The same
+mechanism can be used to adjust a setting globally. By issuing
+@example
+ \property Score.Stem \override #'thickness = #2.0
+@end example
+the entire piece is formatted with thick stems:
+@lilypond
+\score { \notes {
+ \property Score.Stem \override #'thickness = #2.0
+ \once\property Voice. DynamicLineSpanner \override #'padding = #4.0
+ g'4-\f g4
+ }
+\paper { raggedright = ##t }
+ }
+@end lilypond
-We hope that these examples show that music typography is a subtle
-business, and that it requires skill and knowledge to produce good
-engraving. It was our challenge to see if we could put such knowledge
-into a computer program.
+@noindent
+In effect, by setting these variables, users can define their own
+layout styles.
+
+``Plug-ins'' are also implemented using Scheme. A formatting
+``plug-in'' takes the form of a function written in Scheme (or a C++
+function made available as a Scheme function), and it is also stored
+in a variable. For example, the placement of the forte symbol in the
+example above is calculated by the function
+@code{Side_position_interface::aligned_side}. If we want to replace
+this function by a more advanced one, we could issue
+@example
+ \property Voice.DynamicLineSpanner \override #'Y-offset-callbacks
+ = #`(,gee-whiz-gadget)
+@end example
+
+@noindent
+Now, the formatting process will trigger a call to our new
+@code{gee-whiz-gadget} function when the position of the f symbol has
+to be determined.
+
+The full scope of this functionality certainly is intimidating, but
+there is no need to fear: normally, it is not necessary to define
+style-sheets or rewrite formatting functions. In fact, LilyPond gets a
+lot of formatting right automatically, so adjusting individual layout
+situations is not needed very often at all.
@node Music representation
@section Music representation
-One of the big questions when making programs, is what kind of input
-the program should expect. Many music notation programs offer a
+One of the big questions when writing batch programs, is what kind of
+input the program should expect. Many music notation programs offer a
graphical interface that shows notation, and allow you to enter the
-music by placing notes on a staff. Although this is a obvious way to
-design a program, from our point of view, it is cheating. After all,
-the core message of a piece of music notation simply is the music
-itself. If you start by offering notation to the user, you have
-already skipped one conversion, even if it is implicit. If we want to
-generate music notation from something else, then the obvious
-candidate for the source is the music itself.
+music by placing notes on a staff. From our point of view, this design
+is a form of cheating. After all, the core message of a piece of music
+notation simply is the music itself. If you start by offering notation
+to the user, you have already skipped one conversion, even if it is
+implicit. If we want to generate music notation from something else,
+then the obvious candidate for the source is the music itself.
On paper this theory sounds very good. In practice, it opens a can of
worms. What really @emph{is} music? Many philosophical treatises must
-have been written on the subject. Even if you are more practically
-inclined, you will notice that there exist an enormous number of ways
-to represent music in a computer, and they are much more incompatible
-than the formats for word processors and spreadsheets. Anyone who has
-tried to exchange data files from between different notation programs
-can attest to this.
-
-@cindex music representation
-@cindex music expressions
-@cindex input format
-
-This problem is caused by the two-dimensional nature of music: in
-polyphonic music, notes have time and pitch as their two coordinates,
-and they often are related in both directions. Computer files on the
-other hand are essentially one-dimensional: they are a long stream of
-characters. When you represent music in a file, then you have to
-flatten this two-dimensional information breaking either timing or
-pitch relations, and there is no universal agreement on how to do
-this.
-
-Fortunately, we have a concrete application, so we don't run the risk
-of loosing ourselves in philosophical arguments over the essence of
-music. We want to produce a printed score from a music
-representation, so this gives us a nice guide for designing a format:
-we need a format containing mainly musical elements, such as pitch and
-duration, but also enough information to print a score. Our users
-have to key in the music into the file directly, so the input format
-should have a friendly syntax. Finally, we as programmers and
-scientists want a clean formal definition. After all, producing music
-notation is a difficult problem, and in the scientific world, problems
-can only be solved if they are well-specified. Moreover, formally
-defined formats are easier to write programs for.
+have been written on the subject. Instead of losing ourselves in
+philosophical arguments over the essence of music, we have reversed
+the question to yield a more practical approach. Our assumption is
+that the printed score contains all of the music of piece. We build a
+program that uses some input format to produce such a score. Over the
+course of time, the program evolves. While this happens, we can remove
+more and more elements of the input format: as the program improves,
+it can fill in irrelevant details of the input by itself. At some
+(hypothetical) point, the program is finished: there is no possibility
+to remove any more elements from the syntax. What we have left is by
+definition exactly the musical meaning of the score.
+
+There are also more practical concerns. Our users have to key in the
+music into the file directly, so the input format should have a
+friendly syntax. As programmers and scientists, we want a
+clean formal definition. After all, producing music notation is a
+difficult problem, and in the scientific world, problems can only be
+solved if they are well-specified. Moreover, formally defined formats
+are easier to write programs for.
These ideas shaped our music representation: it is a compact format
that can easily be typed by hand. It complex musical constructs from
simple entities like notes and rests, in much the same way that one
builds complex formulas from simple expressions such as numbers and
-mathematical operators. The strict separation between musical
-information and typesetting also gives a blueprint of the program:
-first it reads the music representation, then it interprets the
-music---reading it `left-to-right', and translating the musical
-information to a layout specification. When the layout is computed,
-the resulting symbols are written to an output file.
+mathematical operators.
+
+@node Example applications
+@section Example applications
+
+As programmers and hedonists we enjoy beauty in code, and code that
+produces beautiful typeset music, but nevertheless this program can
+applied to do useful things. In this section, we show a few small
+examples of what is possible.
+
+The simplest application is printing notes.
+
+@lilypond[relative=1]
+ \time 2/4 c4 c g'4 g a4 a g2
+@end lilypond
+
+To these notes, chord names and lyrics may be added, yielding
+a lead sheet.
+
+@lilypond[raggedright]
+\score { <
+ \context ChordNames \chords { c2 c f2 c }
+ \notes \relative c' { \time 2/4 c4 c g'4 g a4 a g2 }
+ \context Lyrics \lyrics { twin4 kle twin kle lit tle star2 } > }
+@end lilypond
+
+The following example combines some more exotic uses of notation
+
+@lilypondfile{screech-boink.ly}
+
+The fragments shown above have all been written by hand, but that is not
+a requirement. Since the formatting engine is mostly automatic, it can
+serve as an output means for other programs that manipulate music. It
+can also be used to convert databases of musical fragments to images for
+use on websites on multimedia presentations.
+
+This manual also shows an application: the input format is plain text,
+and can therefore be easily embedded in other text-based formats, such
+as La@TeX{}, HTML or in the case of this manual, Texinfo. By means of a
+special program, the input fragments can be replaced by music images in
+the resulting PostScript or HTML output files. This makes it easy to
+mix music and text in documents.
+
@node About this manual
@section About this manual
+The manual is divided into the following chapters
+@itemize @bullet
+@item
+@ifhtml The
+@end ifhtml
+@emph{@ref{Tutorial}}
+gives a gentle introduction into typesetting music.
+First time users should start here.
+@item
+@ifhtml
+The
+@end ifhtml
+@emph{@ref{Notation manual}}
+discusses topics grouped by notation construct.
+@item
+@ifhtml
+ The
+ @end ifhtml
+@emph{@ref{Technical manual}}
+@c
+discusses the general design of the program, and how to extend
+functionality.
+@item
+@ifhtml
+ The chapter
+@end ifhtml
+@emph{@ref{Invoking LilyPond}} explains how to run LilyPond and its helper
+programs.
+@end itemize
+
+Once you are experienced, you can simply use the manual as reference:
+there is an extensive index@footnote{If you are looking for something,
+and you cannot find it by using the index, that is considered a bug.
+In that case, please file a bug report.}, but the document is also
+available in
+@ifnothtml
+a big HTML page,
+@end ifnothtml
+@ifhtml
+@uref{../lilypond.html, a big HTML page}
+@end ifhtml
+which can be searched easily using the search facility of a web
+browser.
+@cindex search in manual
+@cindex using the manual
-As you will notice in the coming pages the program makes good
-decisions in a lot of cases: what comes out of LilyPond generally
-looks good. The default layout of lilypond even is suitable for
-publication for some specific files. However, some aspects of the
-formatting are not yet very good. For us programmers, this gives
-inspiration for improving the program. However, most users are more
-interested in improving their printouts, and then they have to make
-manual adjustments to the output. Another aspect of our system of
-encoding through ASCII then shows: it can be complicated to fine tune
-the layout of a piece. There is no graphical user interface, where you
-can simply click and drag a symbol. On the other hand, if you have
-written the code for tuning one specific aspect of the layout, then
-you can simply store the file on disk, retrieve it when you need it:
-there is no need to remember how you did it, since it is all in the
-input file.
-
+@c TODO: advise to buy a book on notation?
+
+If you are not familiar with music notation, or music terminology
+(especially if you are a foreigner), then it is advisable to consult
+the glossary as well. The glossary explains musical terms, and
+includes translations to various languages. It is a
+@ifhtml
+@uref{../glossary.html,separate document}
+@end ifhtml
+@ifnothtml
+separate document, available in HTML and PDF and can be printed as
+well.
+@end ifnothtml
+@cindex idiom
+@cindex jargon
+@cindex terminology
+@cindex foreign languages
+@cindex language
+
+
+This manual is not complete without a number of other documents. They
+are not available in print, but should be included with the
+documentation package for your platform
+
+@itemize @bullet
+@item
+Generated internal documentation.
+@ifhtml
+available @uref{../lilypond-internals/lilypond-internals.html,here}
+@end ifhtml
+
+Almost all formatting functionality that is used internally, is
+available directly to the user. For example, all variables that
+control thicknesses, distances, etc, can be changed in input
+files. There are a huge number of formatting options, and it would be
+impossible to describe them all in a hand-written manual. The
+generated internal documentation is a heavily crosslinked HTML
+document, produced directly from the formatting definitions used. It
+documents the nit-gritty details of each and every LilyPond class, object and
+function.
+
+Each section of the reference manual has a @b{See also}
+subsection, with links (in the HTML document, at least) to the
+generated documentation.
+
+@item
+ Templates
+@ifhtml
+(available @uref{../../../input/templates/out-www/collated-files.html,here})
+@end ifhtml
+
+When you have gone through the tutorial, in theory you are able to
+start writing input files. In practice, writing files from scratch
+turns out to be intimidating. To give a headstart, we have collected
+a number of often-used formats in example files. These files can be
+used as a start, by copying the template, and adding notes in the
+appropriate places.
+
+@item
+ Various input examples
+@ifhtml
+available @uref{../../../input/test/out-www/collated-files.html,here}
+@end ifhtml
@cindex snippets
-@cindex adjusting output
-Lilypond also comes with a huge collection of snippets that show all
-kinds of tricks. This collection is much needed, because of the way
-LilyPond is structured. It is a large program, but almost all of the
-internal functionality is exported: that is, the variables that are
-internally used for formatting the sheet music are available directly
-to the user. These are variables to control thicknesses, distances,
-and other formatting options. There are a huge number of them, and it
-would be impossible to describe them all in a hand-written
-manual. There is no need to despair, there is an `automatic' manual,
-that lists all of the variables that are available. It is directly
-generated from the definitions that LilyPond itself uses, so it is
-always up to date. If you are reading this from a screen: it is
-available from the web, and is included with most binary
-distributions. If you're reading this from paper, then we advise you
-to use the digital version anyway: the hyperlinks make finding topics
-in the lilypond-internals manual much easier.
+These small files show various tips and tricks, and are available as a
+big HTML document, with pictures and explanatory texts included.
+
+
+@item
+ The regression test
+@ifhtml
+available @uref{../../../input/regression/out-www/collated-files.html,here}
+@end ifhtml
+
+We strive to test each feature in one test file. This collection of is
+primarily to help us debug problems, but it can be instructive to see
+how we excercise the program. The format is like the input examples.
+
+@end itemize
+
+The location of the documentation files that are mentioned here can
+vary from system to system. On occasion, this manual refers to
+initialization and example files. Throughout this manual, we refer to
+input files relative to the top-directory of the source archive. For
+example, @file{input/test/bla.ly} may refer to the file
+@file{lilypond-1.7.19/input/test/bla.ly}. On binary packages for the
+Unix platform, the documentation and examples can typically be found
+somewhere below @file{/usr/share/doc/lilypond/}. Initialization files,
+for example @file{scm/lily.scm}, or @file{ly/engraver-init.ly}, are
+usually found in the directory @file{/usr/share/lilypond/}.
+
+@cindex adjusting output
@cindex variables
@cindex properties
@cindex lilypond-internals
@cindex internal documentation
-
-For those who really want to get their hands dirty: it is even
-possible to add your own functionality, by extending LilyPond in the
-built-in scripting language, a dialect of the powerful programming
-language Scheme. There is no real distinction between what a user can
-do and what a programmer is allowed to do.
-
@cindex Scheme
@cindex extending lilypond
-
-In summary, this manual does not pretend to be exhaustive, but it is
-merely a guide that tries to explain the most important principles,
-and shows popular input idioms. The rest of the manual is structured
-as follows: it starts with a tutorial that explains how to use
-lilypond. In the tutorial, a number of fragments of increasing
-complexity are shown and explained. Then comes the reference manual,
-which gives more detailed information on all features. If you're new
-to lilypond, then you should start reading the tutorial, and
-experiment for yourself. If you already have some experience, then
-you can simply use the manual as reference: there is an extensive
-index@footnote{If you are looking for something, and you can't find it
-by using the index, that is considered a bug. In that case, please
-file a bug report}, but the document is also available in One Big Page,
-@c should have hyperlink?
-which is is available for text search using your browser's search
-facility.
-
-@cindex searchin manual
-@cindex using the manual
@cindex bugreport
@cindex index
-@cindex tutorial
-@cindex overview of manual
-@cindex idiom
-
+Finally, this and all other manuals, are available online both as PDF
+files for print and HTML files for browsing. They are available from
+the web site, which can be found at @uref{http://www.lilypond.org/}.
+@cindex website
+@cindex URL
projects / lilypond.git / blobdiff