jazz chords

[Jeff Henrikson]

I have a couple of comments on jazz chords.  This is stuff I have thought for a 
while, but since this is currently being discussed
I thought I'd mention it.

Let's start here:

>The standard chord structure is the 7th chords. Examples:
>
>C-E-G-B would be notated as C triangle
>C-Eb-G-B =3D Cm triangle
>C-Eb-Gb-Bbb =3D Co (no "/7" as in the american chord style)
>C-Eb-Gb-Bb =3D C slashed o
>C-E-G-A =3D C6 (no "maj" as in the american chord style )

There isn't a standard for this.  For example, I am a student at Berklee 
college of music, where despite independent-thinking jazz
mentality there is a standard is because the faculty force one down students' 
throats.  (Don't ask me how they get themselves to
agree!)  The colloquism here would  disagree on the following points:

- maj is better than the triangle (I personally do like the triangle, esp for 
writing things like C-(maj7))
- C maj/triangle should be reserved for C triad, adding a seventh if
 one is desired.  Also the default meaning for a letter alone is major triad.  
This is not so imporant for folk/rock/whatever where
everything is a triad, but it is important in fusions styles where some chords 
are triads and some aren't, and you want to have the
option of being explcit.
- ditto for minor and diminished triads.  Add a 7th if desired.
- write half diminished as minor 7 b5 (I prefer the circle with the slash, no 7)

As for the issue of tensions (aka extensions - see there isn't even a standard 
name for them) the Berklee convention does quite
well on everything from folk to progressive jazz, and the convention is:

- in a tonal jazz context, _do_ notate tensions if and only if they are _not_ 
diatonic to the key signature.  Notate them by any of
b9, 9, #9, 11, #11 b13, 13 inside parenthesis, usually stacked vertically and 
in order.  Special cases for sus4, #5, b5, "6", and
maj7 on minor triad which are all not considered tensions.  Notating the 
tensions is fairly important for tunes with tensions in
the melody (eg, Chelsea Bridge) and gets more important the more non-improvised 
parts there are to the music.  If a horn section in
a recording session is going to be playing natural 9 on a certain dominant 7 
chord, you want to give the piano player a chance to
play it right by telling him so so he doesn't choose #9 and clam.
- in either a folk/pop/rock (triadic) style or an atonal context, notate all 
tensions.


That said, I don't think anybody should go changing lilypond to compensate for 
the Berklee system or any other for that matter, as
they won't mean anything if nobody uses them.

What I am confused about is why knowing what notes are in the chords is any of 
lilypond's business.  Yeah, it's kind of nice for
certain really simple styles for lilypond -m to bang out block chords in whole 
notes, but considering asking a jazz pianist for F7
ususally results in something like

        Eb - A - D - G - B

I don't know many jazz players/writers who really want to hear F A C Eb.  I am 
doing a jazz arrangement right now and the only way
I am keeping myself sane is to hand edit the score to take out the chord 
include line before running -m.  I did another project
where I just wrote the changes in as ugly text.  Maybe there's some easier way 
but I don't know it.

Basically, I think we should let lily just do notation.  Do it right and handle 
the things that it should, but doesn't (to my quite
limited knowledge- apologies if I am incorrect), such as:


         G        Fmaj7 /            (b13)
        ---            / G        F7 (#9 )     D-7  /  / G7 | Cmaj
         F7
         ^this by the way is the               This is how to notate
          more explicit symbol for             rhythm when the melodic
          the voicing above.  The G            staff is already used
          means G major triad.                 for a different rhythm.
                                               In extremely irregular
                                               cases, "slash"
                                               noteheads are specified
                                               just for a measure

Typset the things as symbols, but don't even pretend to know voicings for 
chords, unless there is a reason, like somebody thinks a
really cool hacking project is to get lilypond to look at the melody and chord 
symbols and generate voicings for two hand piano
that fit, (and play in rhythm?) or else can analyze a score in notation and 
lossily reverse construct the chord symbols or
something.  (Incidentally, there is a whole subject called Berklee chord scale 
theory that would make a nice framework.)  IMHO
totally irrelevant for a music typsetting language, but whatever floats your 
boat.  Just draw the symbols and play silence in MIDI.
(Also make sure you have a reasonable way for getting the changes to appear 
only once on the score but printed on every part.)

Basically, by assuming we know the notes ("voicings", as opposed to "chords") 
we are just binding our hands to never really handle
jazz in an even semi-plausable way.



BTW jazzers- this is a tricky way to get something that looks like slashes on a 
staff.  Really stemless diamond noteheads on the C
space, but:

slash = \notes \transpose c' {
        \property Voice.stemLength =  #0
        \property Thread.noteHeadStyle = "diamond"

        c'4

        \property Voice.stemLength =  #7
        \property Thread.noteHeadStyle = ""
}

of course this is for 4/4 on a treble clef.  Gotta change it if you want dotted 
quarter slashes on a 12/8 on a bass part or
whatever.  By any chance, can anybody see a noninvasive way to hack this into 
the fourth notation example by putting it up onto its
own invisible staff and maybe using (ugly but readable) regular text for chord 
symbols?


Jeff Henrikson