05-control-change.py - Adding control changes to our MIDI synthesizer class.

This example adds three continuous MIDI controllers to the previous one (04-simple-midi-synth.py). The first one applied the pitch bend to the transpo argument, which multiply the pitches from the Notein object. The second is a continuous controller used to change the cutoff frequency (hfdamp argument) of the lowpass filter. The last one sets the speed (lfofreq argument) of moving notche oscillations in the spectrum.

from pyo import *
from random import random

class Synth:
    # Added some arguments that will be controlled with MIDI controllers.
    def __init__(self, transpo=1, hfdamp=5000, lfofreq=0.2, mul=1):
        # Transposition factor.
        self.transpo = Sig(transpo)
        # Receive midi notes, convert pitch to Hz and manage 10 voices of polyphony.
        self.note = Notein(poly=10, scale=1, first=0, last=127)

        # Handle pitch and velocity (Notein outputs normalized amplitude (0 -> 1)).
        self.pit = self.note["pitch"] * self.transpo
        self.amp = MidiAdsr(self.note["velocity"], attack=0.001, decay=0.1, sustain=0.7, release=1, mul=0.1,)

        # Anti-aliased stereo square waves, mixed from 10 streams to 1 stream
        # to avoid channel alternation on new notes.
        self.osc1 = LFO(self.pit, sharp=0.5, type=2, mul=self.amp).mix(1)
        self.osc2 = LFO(self.pit * 0.997, sharp=0.5, type=2, mul=self.amp).mix(1)

        # Stereo mix.
        self.mix = Mix([self.osc1, self.osc2], voices=2)

        # High frequencies damping, use argument `hfdamp` to allow MIDI control.
        self.damp = ButLP(self.mix, freq=hfdamp)

        # Moving notches, use argument `lfofreq` to allow MIDI control.
        self.lfo = Sine(lfofreq, phase=[random(), random()]).range(250, 4000)
        self.notch = ButBR(self.damp, self.lfo, mul=mul)

    def out(self):
        "Sends the synth's signal to the audio output and return the object itself."
        return self

    def sig(self):
        "Returns the synth's signal for future processing."
        return self.notch

s = Server()
s.setMidiInputDevice(99)  # Open all input devices.

### Setup the MIDI controllers.

# Bendin can output MIDI note values or transposition factors (scale=1).
# A value of 2 to `brange` argument means that the bending range will be
# 2 semitones above and below the current note.
transpo = Bendin(brange=2, scale=1)

# High frequency damping mapped to controller number 1.
hfdamp = Midictl(ctlnumber=1, minscale=500, maxscale=10000, init=5000)

# Frequency of the LFO applied to the speed of the moving notches.
lfofreq = Midictl(ctlnumber=2, minscale=0.1, maxscale=8, init=0.2)

# Create the midi synth.
a1 = Synth(transpo, hfdamp, lfofreq)

# Send the synth's signal into a reverb processor.
rev = STRev(a1.sig(), inpos=[0.1, 0.9], revtime=2, cutoff=4000, bal=0.15).out()