05.ex-piano-phase.py

#!/usr/bin/env python3

#------------------------------------------------------------------------
# isobar: ex-piano-phase
# 
# Implementation of Steve Reich's "Piano Phase" (1967):
# Two identical piano lines, one with a slightly longer duration,
# moving in and out of phase with one another.
#------------------------------------------------------------------------

from isobar import *
import logging

def main():
    #------------------------------------------------------------------------
    # Melody line
    #------------------------------------------------------------------------
    sequence = PSequence([-7, -5, 0, 2, 3, -5, -7, 2, 0, -5, 3, 2])
    
    #------------------------------------------------------------------------
    # Create a timeline at 160BPM
    #------------------------------------------------------------------------
    timeline = Timeline(160)
    
    #------------------------------------------------------------------------
    # Schedule two identical melodies.
    # We must copy the note sequence or else the position will be stepped
    # by two every note... try removing the .copy() and see what happens!
    #------------------------------------------------------------------------
    timeline.schedule({
        "note": sequence.copy() + 60,
        "duration": 0.5
    })
    timeline.schedule({
        "note": sequence.copy() + 72,
        "duration": 0.5 * 1.01
    })
    
    #------------------------------------------------------------------------
    # Start playing via default MIDI out, and block forever.
    # Alternatively, use timeline.background() to retain foreground control.
    #------------------------------------------------------------------------
    timeline.run()

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