sequencing-example.py

#!/usr/bin/env python3

#------------------------------------------------------------------------
# SignalFlow: Sequencing example.
#
# Complex sequencing is best achieved using a counterpart library
# that is specifically designed for control sequences
# (e.g. https://github.com/ideoforms/isobar). For simple sequences,
# SignalFlow includes several nodes for producing patterns and structure
# within the DSP graph.
#------------------------------------------------------------------------
from signalflow import *
import numpy as np

def main():
    #------------------------------------------------------------------------
    # Create the global processing graph.
    #------------------------------------------------------------------------
    graph = AudioGraph()
    graph.poll(1)

    class SquareArpPatch (Patch):
        #------------------------------------------------------------------------
        # Simple patch that iterates through a sequence of MIDI notes
        # following the given clock
        #------------------------------------------------------------------------
        def __init__(self, clock, seq, fundamental, pan=0.0):
            super().__init__()
            sequence = Sequence(np.array(seq), clock)
            frequency = MidiNoteToFrequency(sequence + fundamental)
            square = SquareOscillator(frequency, width=SineLFO([0.1, 0.11], 0.05, 0.5))
            filter_env = ScaleLinExp(ASREnvelope(0.001, 0.01, 0.1, clock=clock) ** 3, 0, 1, 100, 5000)
            filtered = SVFilter(square, "low_pass", filter_env, resonance=0.2) * 0.2
            balanced = StereoBalance(filtered, pan)
            self.set_output(balanced)

    class HiHatPatch (Patch):
        #------------------------------------------------------------------------
        # Minimum viable hi-hat
        #------------------------------------------------------------------------
        def __init__(self, clock, amp=1.0):
            super().__init__()
            noise = WhiteNoise()
            noise = SVFilter(noise, "high_pass", 8000)
            env = ASREnvelope(0.001, 0.01, 0.1, clock=clock)
            pan = SineLFO(0.5, -0.3, 0.3)
            output = StereoPanner(noise * env * amp, pan)
            self.set_output(output)

    #------------------------------------------------------------------------
    # Create a 16th-beat clock
    #------------------------------------------------------------------------
    bpm = 110
    clock = Impulse(4 * bpm/60)

    #------------------------------------------------------------------------
    # Shared sequence that is used to transpose MIDI notes
    #------------------------------------------------------------------------
    fundamental = Sequence([ 0, -4, -5 ], Impulse(1/4))

    #------------------------------------------------------------------------
    # Create three parallel arpeggios
    #------------------------------------------------------------------------
    graph.play(SquareArpPatch(clock, np.array([ 0, 0, 0, 0, 7, 12, 0, 7 ]) + 36, fundamental))
    graph.play(SquareArpPatch(clock, np.array([ 3, 2, 0, -2, 0]) + 60, fundamental, pan=-0.75))
    graph.play(SquareArpPatch(clock, np.array([ 7, 3, 5, 2, 3, 0 ]) + 72, fundamental, pan=0.75))

    #------------------------------------------------------------------------
    # Add a simple hi-hat sequence
    #------------------------------------------------------------------------
    amp_sequence = Sequence([ 0.1, 0.25, 0.5, 0.1 ], clock=clock)
    graph.play(HiHatPatch(clock, amp=amp_sequence))

    #------------------------------------------------------------------------
    # Run indefinitely.
    #------------------------------------------------------------------------
    graph.wait()

if __name__ == "__main__":
    main()