Just been away at a totally brilliant folk music camp.
Catching up...
John Chambers said
> I've been looking at it from the viewpoint of
> my "tune finder"
The "spectral code" Sigge reported sounds good.
The breachthnaqgh (how do you spell that?) scheme as
outlined seems to require that one determine what key
something is "really" in and where the beats "really" fall.
As tunes can be written with wrong key signatures, wrong
bar lines etc. I would like to modify that to say that you
FIRST record the time spent measure on each note
INCLUDING any accidentals (because I've seen a lot of
modal tunes written in Dm with every single Bb then
naturalised all through the tune.
You probably need to restrict it to "nearest semitone" or
it gets out of hand. You then try to identify the scale from
the pattern of semitones that you get. (This step requires
some research - I want an algorithm which always gives
the same answer (doesn't matter if it's "right") for
a. tunes will all notes of major scale and the *odd* accidental
b. Gapped scales
In fact a tune could be catalogued more than once i.e.
"this is the spectral code that you'd get if you thought it was
really in D and this is what you'd get if it was in A").
You could squeeze into 32 bits a 4 bit precision for
each of the seven degrees of the scale and 4 bits left over.
pre-calculating and storing one 32 bit number for each tune
should be OK.
Next step is a fast algorithm for comparing closeness.
Easy - just the distance in 7 dimensions.
(a^2 +b^2 +c^2 +...+g^2).
Getting through 100,000 of these and picking the
nearest (say) 10 shouldn't take too long.
Sigge said
>So a tune could actually evolve that way.
What do you mean "could". Tens of thousands *have*.
>play some of them in the opposite order
This is rare (Bach sometimes did it) and the result is usually
an unrecognisably different tune. Try and spot them by
*listening* to Bach's Musical Offering. Impossible!
Laurie
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