Manipulating audio signal in input — Pyo 1.0.4 documentation

Pyo 1.0.4 documentation

# Manipulating audio signal in input

02-audio-in.py

The expression illustrated in this example use a phasor signal in input as the running phase of a self-modulated sine wave.

Here is the complete expression:

    (sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))

From inner to outer expression, we have:

    (* $y[-1] 0.8)

Where $y[-1] is the last output sample multiplied by a feedback factor (0.8). Then we have the running phase, $x[0] is the current input sample, rescaled to the range 0 -> 2pi for the sin function:

    (* twopi $x[0])

We add the output delay to the running phase:

    (+ (* twopi $x[0]) (* $y[-1] 0.8))

This gives the modulated running phase driving the sin function:

    (sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))

## Complete example

    from pyo import *

    s = Server().boot()

    expression = """
    // Self-modulated sine wave with running phase given in input.
    // Try different feedback factors between 0 and 1.
    (sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))
    """

    # External signal used as the running phase.
    input = Phasor(86)
    input.ctrl()

    # Create the Expr object and show its expression editor. To
    # re-evaluate the expression hit Ctrl+Enter when the editor
    # has the focus.
    expr = Expr(input, expression, mul=0.5)
    expr.editor()

    # Shows the generated signal.
    sc = Scope(expr)

    # Converts the mono signal to stereo and sends it to the soundcard.
    pan = Pan(expr).out()

    s.gui(locals())