Mixing multiple inputs to multiple outputs with fading time


The Mixer object allows to route multiple inputs to multiple outputs with individual amplitude. A portamento time, defined with the time argument, is applied to amplitude changes to make smooth mixing variations.

The initialization argument outs lets defined the number of available outputs and the argument chnls specifies how many channels per output. If chnls is 2 and a single audio stream is given to an input, the signal will be dupplicated to fill the two channels of the voice.

from pyo import *
import random

s = Server(duplex=0).boot()

# Define some input signals for the mixer.
low = SfPlayer("../snds/flute.aif", speed=0.5, loop=True, mul=0.3)
mid = SfPlayer("../snds/flute.aif", speed=0.75, loop=True, mul=0.3)
hig = SfPlayer("../snds/flute.aif", speed=1.0, loop=True, mul=0.3)

# Mixer with 3 outputs, 2 channels per voice and 0.5 second of amplitude fading time.
mm = Mixer(outs=3, chnls=2, time=0.5)

# Route the mixer's outputs to some effects.
octaveBelow = Harmonizer(mm[0], transpo=-12, feedback=0.25, add=mm[0]).out()
fifthBelow = Harmonizer(mm[1], transpo=-7, feedback=0.25, add=mm[1]).out()
secondAbove = Harmonizer(mm[2], transpo=2, feedback=0.25, add=mm[2]).out()

# Add signals as inputs to the mixer.
mm.addInput(voice=0, input=low)
mm.addInput(voice=1, input=mid)
mm.addInput(voice=2, input=hig)

# Initial assignment of inputs to outputs with amplitude balance.
mm.setAmp(vin=0, vout=0, amp=0.25)
mm.setAmp(vin=1, vout=2, amp=0.25)

# Dictionaries used to print assigment messages.
inputs = {0: "low", 1: "mid", 2: "hig"}
outputs = {0: "Octave below", 1: "Fifth below", 2: "Second above"}

# Dynamic assignation of inputs to outputs with random amplitude.
def assign():
    vin = random.randint(0, 2)
    vout = random.randint(0, 2)
    amp = random.choice([0, 0, 0.25, 0.33, 0.5])
    print("%s -> %s, amp = %f" % (inputs[vin], outputs[vout], amp))
    mm.setAmp(vin=vin, vout=vout, amp=amp)

# Call a new assignment every 3 seconds.
pat = Pattern(function=assign, time=3).play()