22.ex-midi-markov-learner.py

#!/usr/bin/env python3

#------------------------------------------------------------------------
# Parallel markov chain learner:
#
# 1. takes MIDI input, and constructs three markov chains for pitch,
#    duration and amplitude.
# 2. after receiving a keyboard interrupt (ctrl-c), plays back melodies
#    that are statistically similar to the input.
#------------------------------------------------------------------------

from isobar import *
import logging
import time

def main():
    midi_in = MidiInputDevice()
    midi_out = MidiOutputDevice()
    
    learner = MarkovParallelLearners(3)
    clock0 = time.time()
    
    print("Listening for MIDI events...")
    
    try:
        while True:
            message = midi_in.poll()
            if message is not None and message.type == "note_on":
                clock = time.time()
                print("[%f] %s (%d, %d)" % (clock, message, message.note, message.velocity))
    
                velocity = round(message.velocity, -1)
                dur = clock - clock0
                dur = round(dur, 2)
    
                learner.register([message.note, velocity, dur])
                clock0 = clock
    
    except KeyboardInterrupt:
        pass
    
    print("----------------------------------------------------")
    print("Ctrl-C detected, now playing back")
    print("----------------------------------------------------")
    
    chains = learner.chains()
    
    pitch = chains[0]
    amp = chains[1]
    dur = chains[2]
    
    if len(pitch.nodes) == 0:
        print("No notes detected")
    else:
        timeline = Timeline(120, midi_out)
        timeline.schedule({
            "note": pitch,
            "duration": dur,
            "amplitude": amp,
            "channel": 0
        })
        timeline.run()

if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO, format="[%(asctime)s] %(message)s")
    main()