[Class]
midi-key-signature

A MIDI key signature event.

midi-key-signature supports the following slot initializations:

:time number
The start time of the object.
:key integer
An integer -7-7, where -7 means seven flats, 0 means no sharps or flats, and 7 means seven sharps. The default value is 0.
:mode integer
An integer 0-1, where 0 means major and 1 means minor. The default value is 0.

Examples:

Example 1. The midi-key-signature event. 

;;; Ab major
(new midi-key-signature :time 0 :key -4)

;;; A# minor
(new midi-key-signature :time 0 :key 7 :mode 1)

Example 2. Generating time and key signatures. 

(define major (new mode :degrees '(c d e f g a b c)))

(define (gen-measures mea tempo )
  ;; generate measures, each with own time and key signatures
  (let ((tonics (new heap :of '((c 0) (cs 7) (d 2) (ef -3)
                                (e 4) (f -1) (fs 6) (g 1)))))
    (process with rhy = (rhythm 'e tempo)
             repeat mea
             for bpm = (pick 2 3 4 5) ; beats in measure
             for ton = (next tonics)  ; keysig info
             do (transpose major (first ton)) ; shift mode
             output (new midi-key-signature :time (now)
                         :key (second ton))
             output (new midi-time-signature :time (now)
                         :numerator bpm :denominator 4)
             each k = (between 28 42) ; modal keynums 48-72
             as i below (1- (* bpm 2))
             output (new midi :time (+ (now) (* rhy i))
                         :keynum (keynum k :in major)
                         :duration rhy)
             wait (* rhy bpm))))

(events (gen-measures 8 120) "test.mid")
⇒ "test.mid"
(midi-file-print "test.mid")

See also: