04-simple-envelopes.py - ASR and ADSR envelopes.

The Fader object is a simple way to setup an Attack/Sustain/Release envelope. This envelope allows to apply fadein and fadeout on audio streams.

If the dur argument of the Fader object is set to 0 (the default), the object waits for a stop() command before activating the release part of the envelope. Otherwise, the sum of fadein and fadeout must be less than or egal to dur and the envelope runs to the end on a play() command.

The Adsr object (Attack/Decay/Sustain/Release) acts exactly like the Fader object, with a more flexible (and so common) kind of envelope.

from pyo import *
import random

s = Server().boot()

# Infinite sustain for the global envelope.
globalamp = Fader(fadein=2, fadeout=2, dur=0).play()

# Envelope for discrete events, sharp attack, long release.
env = Adsr(attack=0.01, decay=0.1, sustain=0.5, release=1.5, dur=2, mul=0.5)
# setExp method can be used to create exponential or logarithmic envelope.

# Initialize  a simple wave player and apply both envelopes.
sig = SuperSaw(freq=[100, 101], detune=0.6, bal=0.8, mul=globalamp * env).out()

def play_note():
    "Play a new note with random frequency and jitterized envelope."
    freq = random.choice(midiToHz([36, 38, 41, 43, 45]))
    sig.freq = [freq, freq * 1.005]
    env.attack = random.uniform(0.002, 0.01)
    env.decay = random.uniform(0.1, 0.5)
    env.sustain = random.uniform(0.3, 0.6)
    env.release = random.uniform(0.8, 1.4)
    # Start the envelope for the event.

# Periodically call a function.
pat = Pattern(play_note, time=2).play()