Guide to writing abc for abc2midi
---------------------------------

The defining document for abc is the abc version 1.6 specification which can 
be found at http://www.gre.ac.uk/~c.walshaw/abc2mtex/abc.txt . This document
is a description of abc as interpreted by abc2midi.

An abc tune consists of a header followed by a body. Each line in the
header is a different field starting with a letter immediately followed 
by : and then the text of the field. The body of the tune contains lines
of music, though it may also contain certain fields. The end of the tune is
marked by a blank line (so blank lines cannot appear within the tune header
or body). 

Comments are allowed in both the header and the body. A comment starts 
with a % sign and continues to the end of the line. A comment may be on 
a line of its own or at the end of a line of abc.

The header should look something like this :

X:1
T:The Rose Tree
M:4/4
L:1/8
Q:1/4=120
K:G

X: is the reference number (each tune in a file should have a unique reference
number). T: is the title of the tune, M: is the time signature, L: is the
unit note length and K: is the key signature. Q: is the tempo field. In
the above example the tempo is given as 120 quarter-notes per minute. X:
must be the first field and K: must be the last field in the header. 

It is advisable to write the fields M:, L: and Q: in that order. The
reason for this is that M: can set up a unit note length which L:
over-rides and the tempo field Q: can be written in other forms that
depend on unit note length. This order makes the meaning clear and
unambiguous. The original abc specification gives a rule for computing
a default value for the unit note length from the M: field. abc2midi
only uses this rule for choosing a unit note length in the header if
the L: field has been omitted.

Other fields may also appear in the header. Common ones are C: composer 
of the tune, D: discography, H: history of the tune, S: source, N: notes, 
Z: transcription note, A: area from which the tune comes, B: book
and R: rhythm. 

The K: is made up of a base note A-G possibly followed by b for flat or
# for sharp. This specifies a major key. A minor key can be specified
by adding an m while Mixolydian and Dorian modes can be specified by adding
Mix and Dor respectively e.g.

K:Eb
K:EDor
K:EbDor

The following table relates the number of sharps or flats you see on the
stave to what is in the K: field :

7 sharps: C# A#m G#Mix D#Dor
6 sharps: F# D#m C#Mix G#Dor
5 sharps: B  G#m F#Mix C#Dor
4 sharps: E  C#m BMix  F#Dor
3 sharps: A  F#m EMix  BDor
2 sharps: D  Bm  AMix  EDor HP Hp
1 sharp : G  Em  DMix  ADor
0 sharps: C  Am  GMix  DDor
1 flat  : F  Dm  CMix  GDor
2 flats : Bb Gm  FMix  CDor
3 flats : Eb Cm  BbMix FDor
4 flats : Ab Fm  EbMix BbDor
5 flats : Db Bbm AbMix EbDor
6 flats : Gb Ebm DbMix AbDor
7 flats : Cb Abm GbMix DbDor

As an extension, abc2midi also recognizes "Maj" for Major "Min" for Minor,
"Phr" for Phrygian, "Lyd" for Lydian, "Aeo" for Aeolian and "Loc" for
Locrian. Thus CMaj, EPhr, FLyd, AAeo and  BLoc will all generate a stave with 
no sharps or flats. If you use one of these modes in the key signature, it is 
recommended that you add a comment giving the number of sharps or flats for
the benefit of other people who may not be familiar with modes. e.g.

K: DLoc % 3 flats

The key signature may be followed by modifiers. A modifier consists of ^^, ^
=, _ or __ followed by a-g. As an example, ^a means every a should be played
sharp unless otherwise marked in the music. This over-rides whatever has been
set by the key signature. e.g.

K: C ^a

Another extension of the K: field is that it can include a clef specifier and
an octave specifier e.g.

K:G clef=soprano octave=-1

The clef has no effect on the output of abc2midi, but may be used by typesetting
programs. Recognized clefs are treble, bass, baritone, tenor, alto, mezzo
and soprano. There are also variants of these clefs; treble-8 and treble+8
cover ranges which are an octave below and an octave above the normal treble
clef; there are similar variants for the other clefs. The octave specifier
behaves as described below for the I: field.

abc2midi also recognizes the I: (information) field, which can be used as
an alternative way to select the clef and also to shift the range of a 
notated section of music by a whole number of octaves. The general format is

I: key=value [key=value ... ]

where 'key' is a single word with no spaces, but 'value' is a string which
may include spaces, and one I: field can set both the clef and the octave
parameters. 

e.g. 
I:clef=bass octave=-2

When support for different clefs was added to abc2ps (another widely-used
free utility), the clef command also caused octave jumps in the case of
certain clefs. The idea behind this was to make entering music easier, but
it had the unfortunate effect of making abc which used these clefs 
incompatible with other abc programs. For this reason, abc2midi does not
do transposition on the clef command, but introduces a separate command
(octave) which allows the note represention to be shifted by one or more 
octaves when entering a sequence of very low or very high notes. The
intention is to avoid having to type in lots of commas or lots of 
apostrophes. The standard notation may be restored afterwards with
I:octave=0 .

e.g. the passage  B,,, C,, D,, E,, F,, could be written more compactly as

I:octave=-2
B, C D E F
I:octave=0

In more general terms, after the command I:octave=-N,  c  will represent 
a pitch N octaves below its standard pitch value as given in the abc 
1.6 standard.

The I: field is an extension to the abc version 1.6 specification.

The Body of the Tune
--------------------

Following the header is the tune. This is a textual notation for the things
you might see on a stave :

Notes:

A note consists of a pitch specifier followed by a length. Available pitch
specifiers are :

C, D, E, F, G, A, B, C D E F G A B c d e f g a b c' d' e' f' g' a' b'

This covers 4 octaves. abc2midi allows lower octaves to be reached by
adding extra , characters and higher octaves to be reached by adding
extra ' characters. However, this is not standard abc and may not be
supported by other abc utilities.

You can raise or lower the pitch specifier a semitone by preceding it with
^ or _ respectively. The key signature and preceding sharps, flats and
barlines modify the default pitch in the same way as on a stave. Preceding 
a note with = generates natural pitch and ^^ and __ can be used for double 
sharp and double flat respectively.

The length is in general specified by a fraction following the pitch
specifier. However, the notation is made more concise by allowing much
of the fraction to be omitted.

C  - selects a note of 1 unit note length.
C2 - selects a note of 2 unit note lengths.
C/2 - selects a note of 1/2 unit note length.
C3/4 - selects a note of 3/4 unit note length.

C/ is allowed as an abbreviation of C/2.
C// is allowed as an abbreviation of C/4. However, this is not standard
notation and is not allowed by all abc programs.

No space is allowed within a note, but space may be used to separate
notes in the tune.

Rests are written by using 'z' as the pitch specifier.

z3 - a rest of 3 unit note lengths.

Placing a dot before a note causes it to be played staccato.

.e

Combining notes

Three notes of the same length can be turned into a triplet by prefixing
them with (3. This has the effect of multiplying the note lengths by 2/3.
A chord can be represented by bracketting the notes together within [ and
] e.g. [a2e2]. An older notation which is also supported is to use + symbols
e.g. +a2e2+. The - symbol can be used to tie together notes of the same 
pitch e.g. a2-a; this is equivalent to a3.

From version 1.4 of abc2midi, the support of tuples and chords is
extended to include general tuple notation (p:q:r , [ and ] for chords
and a more flexible system of interpreting chords.

(p:q:r means play the next r notes at q/p of their notated value. Thus
(3:2:3 is equivalent to an ordinary triplet (3 .

It is possible in abc to write notes of different lengths within a chord
e.g. [ab2] . In this case, abc2midi takes the length of the first note 
(or rest) in a chord is taken as the time before the next note is played. 
However, if the music is to be typeset, this notation should be avoided
because the output will be ambiguous. Instead, the same effect can be
achieved using tied notes e.g. [ab2] c is equivalent to [ab-] [bc]. 
A tie sign is always assumed to belong to the immediately previous note.

A run of 2 or more different notes may be grouped together in a slur.
This usually means that the notes are to be played together as smoothly as
possible. In typeset music, a slur looks very similar to a tie, but in
abc, ( marks the start of a slur and ) marks the end. e.g. (ABc) .
abc2midi recognizes slurs, but they have no effect on the MIDI generated.

Barlines :

| is an ordinary barline
|| is a double barline
:| is "repeat last section".
|: is "repeat next section".
:: is "repeat last and next sections".
|1 or |[1 or | [1 is "first repeat ending".
:|2 or :|[2 or :| [2 is "second repeat ending".
|] and [| are variants of ||.

A tune with different ending for the first and second repeats has the
general form:

|:  common body of tune  |1  first ending  :|2  second ending  ||

The notation :: is short for :| followed by |: .

Printed music commonly misses out a start repeat at the beginning of a tune.
abc2midi will try to fix up things if you miss out a start repeat. Where a 
tune starts with an anacrusis, abc2midi will always fix a repeat to start at 
the anacrusis rather than the first barline. abc2midi does not allow nested
repeats. Instead, you can use the more versatile part notation to achieve
multiple repeats.

Variant Endings
---------------
abc2midi has been extended so that it understands variant endings if
you use the P: part notation to repeat a section. For example, if the
header of the tune contains P:A4B4 then parts A and B will each be
played 4 times. To play a different ending each time, you could write

P:A
<notes> | [1  <notes>  || [2 <notes> || [3 <notes> || [4 <notes> ||

The Nth ending starts with [N and ends with one of || :| |] or [|. 
You can also mark a section as being used for more than one ending e.g.

[1,3 <notes> ||

plays on the 1st and 3rd endings and

[1-3 <notes> ||

plays on endings 1, 2 and 3. In general, [ can be followed by any list
of numbers and ranges as long as it contains no spaces e.g.

[1,3,5-7  <notes>  || [2,4,8 <notes> ||


Rhythm field and Broken Rhythm Notation
---------------------------------------

R:hornpipe causes notes written in straight time to be played in dotted 
time. The symbol > can be used to achieve a similar effect.

a>b is notated as a3/2b/2 but played as a4/3b2/3.

The symbols < >> << >>> <<< have similar meanings:

a<b   is notated as a/2b3/2 but played as a2/3b4/3.
a>>b  is notated and played as  a7/4b/4.
a<<b  is notated and played as  a/4b7/4.
a>>>b is notated and played as  a15/8b/8.
a<<<b is notated and played as  a/8b15/8.

These times may be adjusted for < and > using the %%MIDI ratio command
described later.

abc2midi may refuse to apply the dotted time symbol if a and b are
not simple notes. In this case, the note lengths should be written
directly.

Guitar chords :

Anything in quotes is a guitar chord e.g.

"A" "Gm" "B7" "Bm7" "D#aug" "Bbdim7"

Guitar chords must use upper case A-G followed by optional # or b, then
the name of a chord type e.g. "m", "aug", "7". abc2midi currently 
recognizes the following chord names :

 m, 7, m7, maj7, M7, 6, m6, aug, +, aug7, dim, dim7, 9, m9, maj9, M9, 
11, dim9, sus, sus9, 7sus4, 7sus9, 5

You can also add your own; see the %%MIDI chordname command below.

abc2midi automatically generates an accompaniment from the guitar chords.
There are a number of default chord/fundamental rhythms for common time 
signatures which this uses, or you can set up your own. 

Lower case a-g followed by optional # or b will generate a single note,
the fundamental, only.

The chord notation also allows chords such as "G/B". The note following
the / is interpreted in one of two ways:

If the note following / does not exist as part of the given chord, it
is added to the chord below the root note of the chord (G in the above
example).

If the note following / does exist in the chord, then the notes of the
chord are re-arranged so that it becomes the lowest pitch note of the
chord. This is known as an inversion of the chord.

This notation has been extended so that finger numbers "1" "2" "3", 
"4" or "5" are allowed. abc2midi ignores these, but a typesetting
program might support them.

You may find some abc tunes that abuse this notation and use quotes 
for things that are not guitar chords. Usually these are
tunes which have been typeset but never played by a computer. If you 
don't want to just delete things in quotes, you can insert one of the 
characters _, ^, @, < or > after the first quote e.g. "_Chorus" 
"_Very Loud". This causes abc2midi to ignore the following text. However, 
typesetting programs should recognize the first character as telling
them where to print the following text.

Another extension is to allow musical instructions to appear in exclamation
marks e.g. !pizzicato! abc2midi currently supports the following :
    !ppp! !pp! !p! !mp! !mf! !f! !ff! !fff!
Default volume is equivalent to !f!. In both the " " and ! ! fields, 
abc2midi allows multiple terms separated by semi-colons e.g. "Am;1".

A line of music may contain any number of notes, barlines and guitar
chords. Spaces may be used to separate these.

Some abc fields may appear within the body of the abc tune :

K: - change key
L: - change unit note length
M: - change meter
Q: - change tempo
P: - part label
V: - voice label
w: - words to be matched syllable by syllable to notes

Each field must be on a line by itself. 

Part Notation
-------------

A part label must be a single character in the range A - Z. e.g.

P:A

A parts specifier in the header can be used to define the MIDI output as
some combination of the specified parts e.g.

P:ABACABA

You can use (  )<number> to repeat a part a specified number of times
e.g. P:A(AB)6 is equivalent to P:AABABABABABAB. If there are no brackets,
just the last part is repeated, so P:AAB3 is equicalent to P:AABBB. Dots
may be inserted into the part specifier to make it easier to read
e.g P:A.AB.AC

If there is no parts specifier, the output is simply the parts (or just
the unlabelled music) in the order in which it appears in the tune body.

You may if you wish have multiple voices sounding concurrently within each
part. These are indicated with V:N to indicate voice number N.

e.g.

V:1
<music for voice part 1>
V:2
<music for voice part 2>
and so on.

A part label implicitly starts with V:1, as does the K: field which starts
the tune body, so you are not allowed to place a part label within a voice. 
The duration of each of the voice parts must be the same for them to 
synchronize correctly; abc2midi will warn you if they are not! From version 
1.7 onwards, abc2midi allows any voice apart from voice 1 to be completely 
omitted from a part.

If no V: field appears after the first K:, whatever follows is assumed to
belong to voice 1 (the default voice). The V: field is an extension to 
abc 1.5. 

The lines between one V:N field and the next V: field define a region 
belonging to voice N. Within a part, you may have more than one such
region for each voice. The music for voice N within a part is all 
the voice N regions taken in sequence.

The M:, L: and K: fields in the header apply to all voices. After
the header, these fields apply only to the voice in which they appear.
In previous versions of abc2midi, an L:, for example, would affect 
everything after it appeared up until the next L:, regardless of what
voice changes there were.

The Q: tempo field should only appear in voice 1 and applies to all voices.

Adding Lyrics to a Tune
-----------------------

The W: field (upper case W) can be used for lyrics to be typeset separately
if the abc is printed out. The w: field (lower case w) in the body of a tune 
supplies a line of lyrics to be matched syllable by syllable to the last line 
of notes. These are usually printed below the notes if the abc is typeset.  
abc2midi uses these to generate karaoke MIDI files. A karaoke MIDI file can
only contain one set of lyrics; abc2midi will generate a warning if the abc 
file contains multiple voices with lyrics in. When the karaoke MIDI file 
is played using an appropriate player program, the lyrics appear on the screen 
with the current syllable highlighted. Within the lyrics, the following 
symbols may be used :

<space> break between words
-       break between syllables within a word
|       advance to next bar
_       indicates last syllable is to be held for another note
*       indicates a one note rest for the singer.
~       appears as a space but connects syllables each side into one.
\-      appears as - in the output
\       continuation character. Next w: field is part of the same line.

A rest is not matched by any lyrics.
A tied note e.g. d2-d2 is treated as 2 notes (or however many parts it
is written as), despite the fact that it only plays as a single note.

abc2midi ignores space characters if they occur either (a) between the 
end of a word/syllable and a hyphen or underscore or (b) between a hyphen or 
underscore and the beginning of a word/syllable. However, some software 
incorrectly treats a hyphen as a separate word if there is a space between 
it and the previous syllable, so, for example, you should write go-ing and 
not go - ing to ensure that your abc is portable between programs.

The following example illustrates most of these :

 gf|e2dc B2A2|B2G2 E2D2|.G2.G2 GABc|d4 B2
w: Sa-ys my au-l' wan to your aul' wan\
w: Will~ye come to the Wa-x-ies dar-gle?

Note that the continuation character is used in a rather strange manner.
One w: field and all continuations will match one line of music, whether
or not the line of music ends with a continuation character. You can
think of the \ in a music line dividing that line into sections and \
in a w: field further dividing these section into sub-sections.

It is possible for a music line to be followed by several w: fields.
This can be used together with the part notation to create verses.
The first w: field is used the first time that part is played, then
the second and so on. If the tune uses repeats, these must be placed
at the end of a line of music in order to make sure that the start of
a w: field matches up with the repeat.

abc2midi-specific commands (%%MIDI)
------------------------------------

abc2midi supports a number of commands of the form

%%MIDI command

Each of these should appear on a line by itself. All of them are allowed 
within the abc tune body. By using these in combination with the part 
notation, one can, for example, play a part transposed or in a different key.

The idea behind this syntax is that other programs will treat it as a
comment and ignore it.

%%MIDI channel n

selects melody channel n (in the range 1-16).

%%MIDI program [c] n

selects program n (in the range 1-128) on channel c. If c is not given, the
program is selected on the current melody channel. Most modern tone
generators follow the General MIDI standard which defines the instrument 
type for each program number. These instrument types are listed at the end
of this document.

%%MIDI beat a b c n

controls the way note velocities are selected. The first note in a bar has
velocity a. Other "strong" notes have velocity b and all the rest have velocity
c. a, b and c must be in the range 0-128. The parameter n determines which
notes are "strong". If the time signature is x/y, then each note is given
a position number k = 0, 1, 2 .. x-1 within each bar. Note that the units for
n are not the unit note length. If k is a multiple of n, then the note is 
"strong". The volume specifiers !ppp! to !fff! are equivalent to the 
following :

!ppp! = %%MIDI beat 30 20 10 1
!pp!  = %%MIDI beat 45 35 20 1
!p!   = %%MIDI beat 60 50 35 1
!mp!  = %%MIDI beat 75 65 50 1
!mf!  = %%MIDI beat 90 80 65 1
!f!   = %%MIDI beat 105 95 80 1
!ff!  = %%MIDI beat 120 110 95 1
!fff! = %%MIDI beat 127 125 110 1

%%MIDI beatstring <string of f, m and p>

This provides an alternative way of specifying where the strong and weak
stresses fall within a bar. 'f' means velocity a (normally strong), 'm' 
means velocity b (medium velocity) and 'p' means velocity c (soft velocity).
For example, if the time signature is 7/8 with stresses on the first, fourth 
and sixth notes in the bar, we could use the following 

%%MIDI beatstring fppmpmp

%%MIDI transpose n

transposes the output by the specified number of semitones. n may be
positive or negative.

%%MIDI rtranspose n

Relative transpose by the specified number of semitones. i.e. 
%%MIDI transpose a followed by %%MIDI rtranspose b results in a
transposition of a+b. %%MIDI transpose b will result in a transposition
of b semitones, regardless of any previous transposition.

%%MIDI c n

specifies the MIDI pitch which corresponds to c. The default is 60. This
number should normally be a multiple of 12.

%%MIDI grace a/b

sets the fraction of the next note that grace notes will take up. a
must be between 1 and b-1.

%%MIDI chordname name n1 n2 n3 n4 n5 n6

Defines how to play a guitar chord called "name". n1 is usually 0 and
n2, n3 to n6 give the pitches of the other notes in semitones relative
to the root note. There may be fewer than 6 notes in the chord, but not 
more.If "name" is already defined, this command re-defines it. Unlike 
most other commands, chordname definitions stay in effect from where they 
are defined to the end of the abc file. The following illustrates how
m, 7, m7 and maj7 could be set up if they were not already defined.
%%MIDI chordname m 0 3 7
%%MIDI chordname 7 0 4 7 10
%%MIDI chordname m7 0 3 7 10
%%MIDI chordname maj7 0 4 7 11

%%MIDI gchord string

sets up how guitar chords are generated. The string is a sequence made of
of z's, c's and f's for rests, chords and fundamental notes respectively.
This specifies how each bar is to be played. An optional length is allowed
to follow the z's, c's and f's  e.g. czf2zf3. If the abc contains guitar 
chords, then abc2midi automatically adds chords and
fundamentals after encountering the first guitar chord. It keeps using that
chord until a new chord is specified in the abc. Whenever the M: field is
encountered in the abc, an appropriate default string is set :

For 2/4 or 4/4 time default is equivalent to :
%%MIDI gchord fzczfzcz

For 3/4 time default is equivalent to :
%%MIDI gchord fzczcz

For 6/8 time default is equivalent to :
%%MIDI gchord fzcfzc

For 9/8 time default is equivalent to :
%%MIDI gchord fzcfzcfzc

%%MIDI chordprog n

Sets the MIDI instrument for the chords to be n.

%%MIDI bassprog n

Sets the MIDI instrument for the bass notes to be n.

%%MIDI chordvol n

Sets the volume (velocity) of the chord notes at n.

%%MIDI bassvol n

Sets the volume (velocity) of the bass notes at n. There is no corresponding
melodyvol command since there are 3 velocity values for melody, set using the
beat command.

%%MIDI gchordon

Turns on guitar chords (they are turned on by default at the start of a
tune).

%%MIDI gchordoff

Turns off guitar chords.

%%MIDI drum string [drum programs] [drum velocities]

This sets up a drum pattern. The string determines when there is a drum beat
and the drum program values determine what each drum strike sounds like.

e.g. %%MIDI drum d2zdd 35 38 38  100 50 50

The string may contain 'd' for a drum strike or 'z' for a rest. By default
a voice starts with no drum pattern and !drum! is needed to enable the
drumming. The drum pattern is repeated during each bar until !nodrum! is
encountered. The %%MIDI drum command may be used within a tune to change
the drum pattern. This command places the drum sounds on channel 10 and
assumes your tone generator complies with the General Midi standard - if
it does not, then you may hear tones instead of drum sounds.

In both the gchord and drum commands, the standard note length of
a single note f,c,z or d is not set by the L: command. Instead it
is adjusted so that the entire gchord string or drum string fits
exactly into one bar. In other words the duration of each note
is divided by the total duration of the string. This means that, 
for example, the drum string "dd" is equivalent to drum string "d4d4".
You cannot currently specify fractions directly (eg. C3/2)
as done in the body of the music, but it is still possible to express
complex rhythms. For example, to indicate a rhythm such as
(3ddd d/d/d/d, you would write the string "d4d4d4d3d3d3d3".

For reference, the percussion instruments defined in the General MIDI 
standard are given below.

35  Acoustic Bass Drum  59  Ride Cymbal 2
36  Bass Drum 1         60  Hi Bongo
37  Side Stick          61  Low Bongo
38  Acoustic Snare      62  Mute Hi Conga
39  Hand Clap           63  Open Hi Conga
40  Electric Snare      64   Low Conga
41  Low Floor Tom       65   High Timbale
42  Closed Hi Hat       66  Low Timbale
43  High Floor Tom      67  High Agogo
44  Pedal Hi-Hat        68  Low Agogo
45  Low Tom             69  Cabasa
46  Open Hi-Hat         70  Maracas
47  Low-Mid Tom         71  Short Whistle
48  Hi Mid Tom          72  Long Whistle
49  Crash Cymbal 1      73  Short Guiro
50  High Tom            74  Long Guiro
51  Ride Cymbal 1       75  Claves
52  Chinese Cymbal      76  Hi Wood Block
53  Ride Bell           77  Low Wood Block
54  Tambourine          78  Mute Cuica
55  Splash Cymbal       79  Open Cuica
56  Cowbell             80  Mute Triangle
57  Crash Cymbal 2      81  Open Triangle
58  Vibraslap    

%%MIDI control [bass/chord] n1 n2 

This generates a MIDI control event. If the word "control" is followed by
"bass" or "chord", the event will be applied to the bass or chord channel,
otherwise it will be applied to the melody channel. n1 and n2 are numbers
in the range 0-127. Generally, n1 selects a control parameter and n2 is
the value to which it is set. A couple of examples :

%%MIDI control 7 50

will set the main volume of the channel to 50

%%MIDI control 10 0

will set the pan parameter (left/right balance) to 0.

See the manual for your MIDI tone generator to find out what control events 
are supported.

%%MIDI nobarlines

This is a somewhat obscure option to support early music without barlines.
Normally, an accidental applied to one note e.g. ^c will apply to every note
at the same point in the scale until the end of the bar (so C,, C, C c c'
would all be sharpened). This option turns off this behaviour, so that an
accidental applies only to the next note. It should be used in the header of
any tune requiring this behaviour.

%%MIDI barlines

This turns off the effect of %%MIDI nobarlines in the middle of a tune. This
is the default behaviour assumed at the start of every tune.

%%MIDI ratio n m

This sets the ratio of note lengths in broken rhythm (e.g. a>b).
The default behaviour is for note a to sound for twice as long as note b.
This can be achieved with

%%MIDI ratio 2 1

and hornpipes are commonly played with approximately this ratio. However,
for other musical styles, a different ratio may be appropriate. If you
are using abc2midi to export music to another program for printing, then
you may wish to use a ratio of 3:1 which is how hornpipes are usually
notated. This can be achieved with

%%MIDI ratio 3 1


Typesetting abc
---------------
If you want to typeset your abc, there are some more features of abc syntax
that you need to know:

If 2 notes appear consecutively with no space between them, they will be
grouped together under the same beam. A space between them prevents them
sharing a beam.

A new line of stave music is generated by the newline at the end of a 
line of abc music. To suppress this, put a \ character at the end of the 
abc music line.

An abc music line should end either at a bar line or at the space
between two notes which indicates they do not share a beam. This is true
whether or not the abc line ends with a \ character.

Error Messages and Warnings
---------------------------

abc2midi attempts to perform various checks on the abc and
reports any problems via error and warning messages:

A warning message indicates there is something strange in the abc - 
possibly an error or possibly non-standard usage.

An error message means that abc2midi thinks there is definitely an 
error in the abc and the MIDI generated may not be correct.

In a small number of cases, an error may cause abc2midi to stop.
This is usually either because it has run out of memory or because
there is some problem with reading or writing a file.


General MIDI Program Number/Instrument Name

 1. Acoustic Grand Piano
 2. Bright Acoustic Piano 
 3. Electric Grand Piano
 4. Honky-tonk Piano 
 5. Electric Piano 1 
 6. Electric Piano 2 
 7. Harpsichord 
 8. Clavi 
 9. Celesta 
 10. Glockenspiel 
 11. Music Box 
 12. Vibraphone 
 13. Marimba 
 14. Xylophone 
 15. Tubular Bells 
 16. Dulcimer 
 17. Drawbar Organ 
 18. Percussive Organ 
 19. Rock Organ 
 20. Church Organ 
 21. Reed Organ 
 22. Accordion 
 23. Harmonica 
 24. Tango Accordion 
 25. Acoustic Guitar (nylon) 
 26. Acoustic Guitar (steel) 
 27. Electric Guitar (jazz) 
 28. Electric Guitar (clean) 
 29. Electric Guitar (muted) 
 30. Overdriven Guitar 
 31. Distortion Guitar 
 32. Guitar harmonics 
 33. Acoustic Bass 
 34. Electric Bass (finger) 
 35. Electric Bass (pick) 
 36. Fretless Bass 
 37. Slap Bass 1 
 38. Slap Bass 2 
 39. Synth Bass 1 
 40. Synth Bass 2 
 41. Violin 
 42. Viola
 43. Cello 
 44. Contrabass 
 45. Tremolo Strings 
 46. Pizzicato Strings 
 47. Orchestral Harp 
 48. Timpani 
 49. String Ensemble 1 
 50. String Ensemble 2 
 51. SynthStrings 1 
 52. SynthStrings 2 
 53. Choir Aahs 
 54. Voice Oohs 
 55. Synth Voice 
 56. Orchestra Hit 
 57. Trumpet 
 58. Trombone 
 59. Tuba 
 60. Muted Trumpet 
 61. French Horn 
 62. Brass Section 
 63. SynthBrass 1 
 64. SynthBrass 2 
 65. Soprano Sax
 66. Alto Sax 
 67. Tenor Sax 
 68. Baritone Sax 
 69. Oboe 
 70. English Horn
 71. Bassoon 
 72. Clarinet 
 73. Piccolo
 74. Flute 
 75. Recorder 
 76. Pan Flute
 77. Blown Bottle
 78. Shakuhachi 
 79. Whistle 
 80. Ocarina 
 81. Lead 1 (square) 
 82. Lead 2 (sawtooth)
 83. Lead 3 (calliope) 
 84. Lead 4 (chiff) 
 85. Lead 5 (charang) 
 86. Lead 6 (voice) 
 87. Lead 7 (fifths) 
 88. Lead 8 (bass + lead)
 89. Pad 1 (new age)
 90. Pad 2 (warm) 
 91. Pad 3 (polysynth)
 92. Pad 4 (choir) 
 93. Pad 5 (bowed) 
 94. Pad 6 (metallic) 
 95. Pad 7 (halo) 
 96. Pad 8 (sweep) 
 97. FX 1 (rain) 
 98. FX 2 (soundtrack) 
 99. FX 3 (crystal) 
 100. FX 4 (atmosphere) 
 101. FX 5 (brightness) 
 102. FX 6 (goblins) 
 103. FX 7 (echoes) 
 104. FX 8 (sci-fi) 
 105. Sitar 
 106. Banjo 
 107. Shamisen 
 108. Koto 
 109. Kalimba 
 110. Bag pipe 
 111. Fiddle 
 112. Shanai 
 113. Tinkle Bell 
 114. Agogo 
 115. Steel Drums 
 116. Woodblock 
 117. Taiko Drum 
 118. Melodic Tom 
 119. Synth Drum 
 120. Reverse Cymbal 
 121. Guitar Fret Noise 
 122. Breath Noise 
 123. Seashore 
 124. Bird Tweet 
 125. Telephone Ring 
 126. Helicopter 
 127. Applause 
 128. Gunshot

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This reference written 1995-1998 by James Allwright