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:
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())