Setting audio object parameter’s value with portamento

The set() method of the PyoObject lets the user define a new value for a given parameter with a portamento time to reach the target. Optionally, a function to call at the end of the ramp can be given to the callback argument.

The signature of the method is:

PyoObject.set(attr, value, port=0.03, callback=None)


  • attr is the name of the attribute as a string.

  • value is the target value (can be a list if object has multiple streams).

  • port is the portamento time in seconds.

  • callback is a function to call when the ramp is done.

from pyo import *
from random import uniform

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

# 10 frequency modulations with random parameters.
a = FM(
    carrier=[uniform(197, 203) for i in range(10)],
    ratio=[uniform(0.99, 1.01) for i in range(10)],
    index=[uniform(5, 10) for i in range(10)],

def go():
    "Linear ramps between the current values and the new ones in 9.5 sec."
    # Choose new targets and start the ramps.
    a.set("carrier", [uniform(395, 405) for i in range(10)], 9.5)
    a.set("ratio", [uniform(0.49, 0.51) for i in range(10)], 9.5)
    # Call the reset() function when portamentos are done.
    a.set("index", [uniform(10, 15) for i in range(10)], 9.5, callback=reset)

def reset():
    "Instantaneous jumps to new values."
    a.carrier = [uniform(197, 203) for i in range(10)]
    a.ratio = [uniform(0.99, 1.01) for i in range(10)]
    a.index = [uniform(5, 10) for i in range(10)]

# Call the go() function every 10 seconds.
pat = Pattern(go, time=10).play()