
NAME

     Octaves --  how to do pitches

DESCRIPTION

     The LilyPond input language, Mudela (help, silly name),
should be easy to read and write.  In my  experience  Mudela
is  already quite convenient for entering music.  Every time
I've entered a substantial piece of music, however, I  found
that  I  made quite a few mistakes.  The MIDI output helps a
lot with locating and correcting the  errors.   There's  one
type  of  error that seems to be frequent, stubborn and hard
to catch, and that's the  octavation  error.   The  relative
octave  feature is an attempt to make Mudela a bit easier to
write.  In addition, this feature makes it  harder  to  make
octavation  mistakes, yet if you made one, its a lot simpler
to find and correct.  Here's how it works.

o    forget the old "\octave c';" command

o    forget the old octave boundaries with octaves c  ..  c'
     You  can  enter  a  piece of music in relative mode, by
     typing

              \melodic \relative c { ... }

From then on, the pitch of a note will be the closest to the
last  one, assuming that large intervals are a lot more rare
than small ones.  Thus, you can enter a scale without  using
octavation quotes:

         c d e f g a b c

the  last  c  being an octave higher than the first.  If you
have to enter an interval that is greater than a fourth, you
must specify whether the pitch goes up, using post-quotes:

         c c' % octave up
         c g' % fourth up

or down, using pre-quotes:

         c c, % octave down
         c f, % fourth down

CONVERTING

To  convert  a  piece  of music from the old absolute-octave
notation to relative  octaves,  lilypond  provides  the  -Q,
--find-fourths  feature  to locate all big intervals in your
music (sorry, fully automated convert is too complex).

First, edit the .ly file, add "\relative c" to  all  melodic
chunks:

         foo = \melodic \relative c { ... }

and  remove  all  "\octave " commands.  See the example file
input/test/find-fourths.ly.

Use lily to find the fourths

         lilypond -Q find-fourths.ly 2>&1 | tee fourths
         ...
         find-fourths.ly:3:18: warning: Interval greater than fourth, relative: g':
                 c d c f c g
                          c b, c g, c f, c c'' c

         find-fourths.ly:3:20: warning: Interval greater than fourth, relative: c,:
                 c d c f c g c
                         b, c g, c f, c c'' c

Then, load a copy  of  the  original  mudela  file  in  your
favourite  editor,  and let it parse the 'error file' inter-
vals.  First you remove all octavation quotes.  Then,  jump-
ing  from  warning to warning, you enter quotes as suggested
by LilyPond.
