Let me be clear - I am NOT pushing for ABC to support
precisely the set of things that Muse accepts. I'd prefer
it to be a smaller set. I see no real virtue in having
three (or more?) different ways to write "diminished".
I was aware that the thing in Mike's mail wasn't the abc2midi
spec - that's why I asked for it.
What I would like to see as ABC is as follows
I hope the meta-syntax is obvious, here's a clue
<chord> = A | B[c]
would mean that a chord could be A or B or Bc
with no other possibilities. Here we go...
<guitar chord> = <silence>|<chord>
<silence> = X
<chord> = <root>[<modifier>][/<bass>]
<root> = <note>
<bass> = <note>
<note> = <note letter>[<accid>]
<note letter> = A|B|C|D|E|F|G
<accid> = #|b
<modifier> = m|m7||maj7|dim|aug|!|4|5|6|7|9
This means that there is only one true way to write
G minor, to wit Gm - Gmin may or may not work.
If a program accepts a superset, then it should
ideally emit a warning diagnostic.
Semantics (what it means).
If there is no /<bass> option:
The lowest note in the chord is given by the chord
letter, possibly sharpened or flattened in an obvious
way, in some octave not specified by ABC.
the notes of the chord are given below in
ascending order of pitch for the case of root note C.
For other root notes, all notes in the chord,
including the root are shifted by the same
number of semitones.
[no modifier] => C E G
m => C Eb G
m7 => C Eb G Bb
maj7 => C E G B
dim => C Eb F# A
aug => C E G#
! => C
4 => C F G
5 => C G
6 => C E G A
7 => C E G Bb
9 => C E G D or C E G C D (but not C D E G)
Where the </bass> option is used then
If the <bass> note is in the chord then the chord
is inverted so as to make that note the lowest in
the chord. For instance,
C/G => G C E
D7/C => C D F# A
If the bass note is not in the chord, then it is
added.
e.g. C/A => A C E G
[Does it have to be added as the lowest note
in the chord??
Could C/A be another name for C6??]
Laurie
P.S. I've tried to be even handed. This lot would
give me some implementation work to do in Muse.
I prefer F! to f because
1. it seems more consistent
2. it means that "fine" is not taken as an F chord,
even though it should be written "^fine".
----- Original Message -----
From: Mike Whitaker <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, February 14, 2001 3:52 PM
Subject: Re: [abcusers] Chord notation
On Wed, Feb 14, 2001 at 12:52:44PM -0000, Laurie Griffiths wrote:
> Mike Whitaker said
> "... what Muse does isn't compatible with what abc2midi does..."
>
> Has someone got a description of what abc2midi does?
from abcguide.txt
-----
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,
Lower case a-g followed by optional # or b will generate a single note,
the fundamental, only.
----------
> I noticed someone say that abc2midi uses
me
> f where Muse uses F! to mean the single note.
See above.
> Is there more? Muse seems to me to implement something very close to a
> superset of the draft spec and I don't see any incompatibilities with it.
> To unpick Mike's mail a phrase at a time:
Hold it! That's not me you're quoting, that's the current abc draft.
See below that in my mail for my proposed changes.
> Muse allows in addition
> - or 0 to mean diminished
see my comments about '+' below. Also 'o' gets used for diminished
> ! to mean just the root note
see above
> 6 to mean 6th (was this part of "etc."?)
> +4 to mean root, fourth and fifth e.g. C+4 is C F G
that's usually sus4
> 5 to mean root and fifth only e.g. C5 is C G
> X as a chord name to mean silence.
> / as a chord name to mean "repeat the previous chord". (This could be
> ambiguous where the flow of a song allows two different precursors for
> instance at the start of a repeat. Bad idea to use this at the start of
any
> such section.)
>
> and Muse has a more explicit grammar for the "type", to wit
> [m|min|7|m7|min7|maj7|-|dim|0|+[4]|aug|!|6|5]
>
> or, in future
> [m|min|maj|7|m7|min7|maj7|-|dim|0|+[4]|aug|!|6|5]
I'm *very* twitchy about using "+" at all, since I've seen it mean
'sharpened' 'added' or 'augmented'
so C+9 could mean C(#9): C E G Bb D# (sharpened 9)
Cadd9: C E G D (added 9)
or Caug9: C E G# Bb D (augmented 9)
--
Mike Whitaker | Work: +44 1733 766619 | Work: [EMAIL PROTECTED]
System Architext | Fax: +44 1733 348287 | Home: [EMAIL PROTECTED]
CricInfo Ltd | GSM: +44 7971 977375 | Web: http://www.cricinfo.com/
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