01-dynamic-range.py - Adjust the dynamic range of the signal. — Pyo 1.0.4 documentation

Pyo 1.0.4 documentation

# 01-dynamic-range.py - Adjust the dynamic range of the signal.

Comparison of three objects used to adjust the dynamic range of the signal.

- Compress : Reduces the dynamic range of an audio signal.

- Expand : Increases the dynamic range of an audio signal.

- Gate : Allows a signal to pass only when its amplitude is above a threshold.

These three objects, by default, process independently each audio stream relatively to its own RMS value. This can be a problem if they are passed a stereo signal (or any multiphonic signals) where both channels should be processed in the same way.

An alternative usage to the one illustrated below is to mix a multi-channel signal prior to the dynamic processor and to tell the object to output the amplitude value that should be applied to all streams at once. Something like this:

    >>> sf = SfPlayer("your/stereo.sound.wav")
    >>> cmp = Compress(sf.mix(1), thresh=-18, ratio=3, outputAmp=True)
    >>> # Compress both signal with the common amplitude curve.
    >>> compressed = sf * cmp

    from pyo import *

    s = Server().boot()

    # The original source.
    src = SfPlayer("../snds/drumloop.wav", loop=True)

    # The three dynamic processing.
    cmp = Compress(src, thresh=-18, ratio=3, risetime=0.005, falltime=0.05, knee=0.5)
    exp = Expand(src, downthresh=-32, upthresh=-12, ratio=3, risetime=0.005, falltime=0.05)
    gat = Gate(src, thresh=-40, risetime=0.005, falltime=0.05)

    # These are labels that are shown as the scope window title.
    labels = ["Original", "Compressed", "Expanded", "Gated"]

    # List of signals to choose from.
    signals = [src, cmp, exp, gat]

    # Selector is used here to choose which signal to listen to.
    output = Selector(signals)

    # Converts the signal from mono to stereo.
    stout = output.mix(2).out()

    # Live oscilloscope of the alternated signals.
    sc = Scope(output, wintitle="=== Original ===")

    # The endOfLoop function cycles through the different signals
    # and change the selection of the Selector object.
    num_of_sigs = len(signals)
    c = 1

    def endOfLoop():
        global c
        output.voice = c
        if sc.viewFrame is not None:
            sc.viewFrame.SetTitle("=== %s ===" % labels[c])
        c = (c + 1) % num_of_sigs

    # endOfLoop is called every time the SfPlayer reaches the end of the sound.
    tf = TrigFunc(src["trig"], endOfLoop)

    s.gui(locals())