“Scribbletune” Ответ

Scribbletune

const scribble = require('scribbletune');
  const clips = ['1032', '2032', '4021', '3052'].map(order =>
    scribble.clip({
      pattern: '[xx][xR]'.repeat(4),
      notes: scribble.arp({
        chords: 'Dm BbM Am FM BbM FM CM Gm',
        count: 8,
        order,
      }),
      accent: 'x-xx--xx',
    })
  );
  scribble.midi([].concat(...clips), 'chords.mid');