Accessing Sox Audio Effects from Python via Pysox

apply_sox_effect.py

import pysox
import librosa
import numpy as np

def apply_sox_effect(signal, sr, fxstr):
    # This writes signal to a .wav file, processes it sox to another file, loads that and returns it.
    #
    # signal:  a numpy list of numbers; the audio signal
    # sr:      the sample rate in Hz, must be an integer
    # fxstr:   a semicolon-separated string starting with the effect name followed by parameter values in order
    #          e.g., "lowpass;500" or "vol;18dB" or 'compand;0.3,0.8;-50', or if you're feeling ambitious,..
    #                fxstr='ladspa;/usr/lib/ladspa/mbeq_1197.so;mbeq;-2;-3;-3;-6;-9;-9;-10;-8;-6;-5;-4;-3;-1;0;0;0' 
    #          See the sox docs for more on effects: http://sox.sourceforge.net/sox.html#EFFECTS
    #          (Why semicolon-separated?  Because sox looks for both commas and colons!)
    inpath, outpath = 'in.wav', 'out.wav'
    librosa.output.write_wav(inpath, signal, sr)                     # write the input audio to a file
    tmp = fxstr.split(';')
    fxname = tmp[0]
    fxvals = [str.encode(x) for x in tmp[1:]]
    effectparams = [(fxname, fxvals),]
    app = pysox.CSoxApp(inpath, outpath, effectparams=effectparams)   # apply the sox effect & get new file
    app.flow()

    out_signal, sr = librosa.load(outpath, sr)
    return out_signal



sr = 44100
noise = np.random.rand(4*sr) - 0.5     # 4 seconds of noise
new_noise = apply_sox_effect(noise, sr, 'lowpass;500')