+
+
+@node Extracting musical information
+@section Extracting musical information
+
+In addition to creating graphical output and MIDI, LilyPond can
+display musical information as text.
+
+@menu
+* Displaying LilyPond notation::
+* Displaying scheme music expressions::
+* Saving music events to a file::
+@end menu
+
+@node Displaying LilyPond notation
+@subsection Displaying LilyPond notation
+
+@funindex \displayLilyMusic
+Displaying a music expression in LilyPond notation can be
+done with the music function @code{\displayLilyMusic} but only when
+using the command line. For example,
+
+@example
+@{
+ \displayLilyMusic \transpose c a, @{ c4 e g a bes @}
+@}
+@end example
+
+will display
+
+@example
+@{ a,4 cis e fis g @}
+@end example
+
+By default, LilyPond will print these messages to the console
+along with all the other LilyPond compilation messages. To split
+up these messages and save the results of @code{\display@{STUFF@}},
+redirect the output to a file.
+
+@example
+lilypond file.ly >display.txt
+@end example
+
+
+@node Displaying scheme music expressions
+@subsection Displaying scheme music expressions
+
+See @rextend{Displaying music expressions}.
+
+
+@node Saving music events to a file
+@subsection Saving music events to a file
+
+Music events can be saved to a file on a per-staff basis by
+including a file in your main score.
+
+@example
+\include "event-listener.ly"
+@end example
+
+This will create file(s) called @file{FILENAME-STAFFNAME.notes} or
+@file{FILENAME-unnamed-staff.notes} for each staff. Note that if
+you have multiple unnamed staves, the events for all staves will
+be mixed together in the same file. The output looks like this:
+
+@example
+0.000 note 57 4 p-c 2 12
+0.000 dynamic f
+0.250 note 62 4 p-c 7 12
+0.500 note 66 8 p-c 9 12
+0.625 note 69 8 p-c 14 12
+0.750 rest 4
+0.750 breathe
+@end example
+
+The syntax is a tab-delimited line, with two fixed fields on each
+line followed by optional parameters.
+
+@example
+@var{time} @var{type} @var{...params...}
+@end example
+
+This information can easily be read into other programs such as
+python scripts, and can be very useful for researchers wishing to
+perform musical analysis or playback experiments with LilyPond.
+
+
+@knownissues
+
+Not all lilypond music events are supported by
+@file{event-listener.ly}. It is intended to be a well-crafted
+@qq{proof of concept}. If some events that you want to see are
+not included, copy @file{event-listener.ly} into your lilypond
+directory and modify the file so that it outputs the information
+you want.