chaotic-feedback-example.py

#!/usr/bin/env python3

#------------------------------------------------------------------------
# SignalFlow: Chaotic feedback from FM self-modulation.
#------------------------------------------------------------------------
from signalflow import *

def main():
    graph = AudioGraph()
    graph.poll(1)

    #------------------------------------------------------------------------
    # Once per second, select a new random frequency (40-20000Hz)
    #------------------------------------------------------------------------
    f0 = RandomExponential(40, 2000, clock=RandomImpulse(1))

    #------------------------------------------------------------------------
    # Allocate a one-second buffer for use in the feedback line.
    #------------------------------------------------------------------------
    buf = Buffer(1, graph.sample_rate)

    #------------------------------------------------------------------------
    # op1 self-modulates by sending its output value to a
    # FeedbackBufferWriter, and reading its previous outputs from a
    # FeedbackBufferReader.
    #------------------------------------------------------------------------
    feedback = FeedbackBufferReader(buf)
    op0 = SineOscillator(f0 + f0 * feedback * 14)

    #------------------------------------------------------------------------
    # Alter the level of self-oscillation once per second.
    # Pass an array to RandomImpulse to generate different randomised
    # sequences in the L/R channels, for stereo output.
    #------------------------------------------------------------------------
    level = Smooth(RandomUniform(0, 1, clock=RandomImpulse([0.5, 0.5])))
    level = ScaleLinExp(level, 0, 1, 0.0001, 1.0)
    op0 = op0 * level
    graph.add_node(FeedbackBufferWriter(buf, op0, 0.5))

    #------------------------------------------------------------------------
    # Use the chaotic output of op0 to modulate a second sine oscillator.
    #------------------------------------------------------------------------
    op1 = SineOscillator(f0 + f0 * op0 * 14)

    graph.play(op1)
    graph.wait()

if __name__ == "__main__":
    main()