How to send multiple outputs from a single expression — Pyo 1.0.4 documentation

Pyo 1.0.4 documentation

# How to send multiple outputs from a single expression

09-multiple-outputs.py

If the object generates only one channel output (the default), the last expression in the script is the output signal. Otherwise, output signals must be created with the out function.

Here is an example of a script that output four sine waves to four different output channels.

    (define osc (sin (* twopi (~ $1))))
    (out 0 (* (osc 250) 0.2))
    (out 1 (* (osc 500) 0.2))
    (out 2 (* (osc 750) 0.2))
    (out 3 (* (osc 1000) 0.2))

We retrieve the different channels from the Expr object with the bracket syntax (obj[0] is the first channel, obj[1] the second, and so on…).

    from pyo import *

    s = Server().boot()

    expression = """// Lorenz strange attractor.
    // Control variables
    (let #pit 500)      // 1.0 -> 750.0
    (let #chaos 2.0)    // 0.5 -> 3.0
    // Initial constants
    (let #A 10.0)
    (let #B 28.0)

    // Computes the differential variables
    (let #delta (* (/ 1.0 sr) #pit))
    (let #vDX (* (- $y1[-1] $y0[-1]) #A))
    (let #vDY (- (* $y0[-1] (- #B $y2[-1])) $y1[-1]))
    (let #vDZ (- (* $y0[-1] $y1[-1]) (* #chaos $y2[-1])))

    // Three differential equations (the first two are the
    // desired audio signals).
    (out 0 (+ $y0[-1] (* #vDX #delta)))
    (out 1 (+ $y1[-1] (* #vDY #delta)))
    (out 2 (+ $y2[-1] (* #vDZ #delta)))

    """

    # We must tell the Expr object how many signals to output with the `outs` argument.
    # The `initout` argument sets the initial value og output signals (defaults to 0).
    expr = Expr(Sig(0), expression, outs=3, initout=1.0, mul=[0.044, 0.0328, 0.0])
    expr.editor()

    sc = Scope(expr)
    sp = Spectrum(expr)

    pan = Pan(expr, mul=0.3).out()

    s.gui(locals())