Here is a transcription of code from an article on music syntax in APL2 and
some simple MIDI
The article reference is in the code. If you have an ACM membership you should
be able to download
The PDF of the article
Tom McGuire
NB. MusicalSyntax.ijs - J implementation of functions from APL90
NB. paper: Friis ES, Jordan S "Musical Syntactic and Semantic
Structures in
NB. APL2"
NB. J Author: Tom McGuire
NB.
splice =: 13 : ',&.>/ y'
scale =: 0 2 4 5 7 9 11
Notes =: 'ABCDEFG'
ChordNames =: (1$'M');(1$'m');'M7';'m7';(1$'o')
ChordTypes =: 'major';'minor';'major7';'minor7';'diminished'
CS =:
(1$'C');'C#';(1$'D');'D#';(1$'E');(1$'F');'F#';(1$'G');'G#';(1$'A');'A#';1$'B'
NB. DTmajor diatonic chords for a major scale
NB. used as indexes into ChordNames and ChordTypes
DTmajor =: 0 1 1 0 0 1 4
M =: 0 4 7
m =: 0 3 7
o =: 0 3 6
M7 =: 0 4 7 11
m7 =: 0 3 7 10
NB. Midi event creation
note_on =: 13 : '144,y,64'
note_off =: 13 : '128,y,64'
Scale =: 60 + scale NB. middle C major scale
NB. diatonic tonalities generates chords of a major scale
DT =: 13 : ' splice"1 (DTmajor { ChordNames),.~ scale { (CS i. <y) |. CS'
NB. arp - arpeggiate a chord into its 3 note pitches
arp =: 13 : '( ". 1}.y) { (CS i. <1{. y) |. CS'
NumToName =: 3 : 0
'octave pc' =. 0 12 #: y
octave =. ": octave - 1
pc =. >pc { CS
pc,octave
)
NB. example usage
NB. NumToName 60 - returns middle C with its octave
NB. NumToName each ;/60 + scale - produces all the notes in middle C with octave
NB. DT 'C' - will produce boxed list of diatonic chords for Cmajor scale
NB. DT each CS - produces all 12 distinct diatonic tonalities
NB. arp each DT 'C' - produces a boxed list of 3 note diatonic tonality chords
NB.
NB. MIDI event parsing
NB. X =: 144 64 64 144 67 64 144 71 64 128 64 64 128 67 64 128 71 64
NB. EVENTS =: _3 <\X
NB.
NB. to get the notes in the EVENTS
NB. 1&{ each (;144&e. each EVENTS)#EVENTS
NB.
NB. to convert the note names:
NB. NumToName each 1&{ each (;144&e. each EVENTS)#EVENTS
> On Mar 28, 2020, at 5:27 PM, Devon McCormick <[email protected]> wrote:
>
> Hi -
> has anyone done work with generating music or musical phrases in J? I'm
> helping someone develop a music training game that starts by generating
> sounds with a particular key, tempo, and phrase length. The idea is to
> help students to train their ears by testing them on their ability to play
> back a randomly-generated musical phrase.
>
> I've told my collaborator that I think the generation part should be
> relatively straightforward but I am not schooled in music, so I'm not sure
> how to start.
> I'm guessing that the second part of comparing the user's response to the
> generated phrase will be more difficult but I'd like to get any kind of
> start I can.
>
> Does anyone have any ideas about this?
>
> Thanks,
>
> Devon
>
> --
>
> Devon McCormick, CFA
>
> Quantitative Consultant
> ----------------------------------------------------------------------
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