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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
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 is 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.
+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::
+* Computerized typography ::
* Music representation::
-* Program design::
* Example applications::
* About this manual::
@end menu
@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.
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
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.
+is acceptable for publication.
-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 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 how ugly
-the fonts were that we admired at first.
+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]
@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
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
-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
+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
+
+@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. From our point of view, this design
is a form of cheating. After all, the core message of a piece of music
@node Example applications
@section Example applications
-As programmers and hedonists enjoy beautifully written code, and
-beautifully printed music, but this program can applied to
-do useful things. In this section, we show a few small examples of
-what is possible.
+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.
-[todo: show examples]
+The simplest application is printing notes.
+@lilypond[relative=1]
+ \time 2/4 c4 c g'4 g a4 a g2
+@end lilypond
-The following example combines some more exotic uses of notation
+To these notes, chord names and lyrics may be added, yielding
+a lead sheet.
-@lilypondfile{screech-boink.ly}
+@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.
@section About this manual
The manual is divided into the following chapters
-@table @strong
-@item Tutorial
- Gives a gentle introduction into typesetting music.
- Start here if you have never used lilypond before.
-@item Reference manual
- Here, each aspect of typesetting music is discussed.
-@item Internals
- This chapter discusses how it works from the inside, and how you can
- extend the program.
-@item Invoking
- This chapter explains how to runn LilyPond and its helper programs.
-@end itemize
-
-Once you are experienced with, 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
+@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
-One Big Page,
+ 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
-@uref{One Big Page,../lilypond.html}
+a big HTML page,
@end ifnothtml
-which is is available for text search using your browser's search
-facility.
+@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
+@c TODO: advise to buy a book on notation?
-If you are familiar with music notation, and music terminology
+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. This documents explains many terms, and includes
-translations to various languages. It is a
+the glossary as well. The glossary explains musical terms, and
+includes translations to various languages. It is a
@ifhtml
-@uref{separate document,../glossary.html}
+@uref{../glossary.html,separate document}
@end ifhtml
@ifnothtml
-separate document, and can be printed as well.
+separate document, available in HTML and PDF and can be printed as
+well.
@end ifnothtml
@cindex idiom
@cindex jargon
@item
Generated internal documentation.
@ifhtml
-available @uref{here,../lilypond-internals/lilypond-internals.html}
+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 from input
+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
-the nit-gritty details of each and every LilyPond class, object and
+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}
@item
Templates
@ifhtml
-available @uref{here,../../../input/templates/out-www/collated-files.html}
+(available @uref{../../../input/templates/out-www/collated-files.html,here})
@end ifhtml
- When you have gone through the tutorial, you theoretically should be
-able to start writing input files. However, this turns out to be a
-little intimidating. To give you a headstart, we have collected a
-number of often-used formats in example files. You can take one of
-these example files, and add notes in the appropriate places to
-generate output.
+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{here,../../../input/test/out-www/collated-files.html}
+available @uref{../../../input/test/out-www/collated-files.html,here}
@end ifhtml
@cindex snippets
-These small files show various applications of lilypond, and are
-available as a big HTML document, with pictures and explanatory texts
-included.
+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{here,../../../input/regression/out-www/collated-files.html}
+available @uref{../../../input/regression/out-www/collated-files.html,here}
@end ifhtml
-We strive to test each feature in a collection of input snippets. This
-is primarily to help us debug the program, but it can be instructive
-to see how we excercise the program. The format is like the input
-examples.
+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 extending lilypond
@cindex bugreport
@cindex index
+
+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