import wave
import pyaudio
import numpy as np
import os, copy
import math
from scipy.io.wavfile import write
from scipy.io.wavfile import read
from numpy import cos, sin, pi, absolute, arange, log10
from scipy.signal import kaiserord, lfilter, firwin, freqz, hilbert
from pylab import figure, clf, plot, xlabel, ylabel, xlim, ylim, title, grid, axes, show, semilogx, xticks
import numpy as np
import matplotlib.pyplot as plt

INT16_FAC = (2**15)-1
INT32_FAC = (2**31)-1
INT64_FAC = (2**63)-1
norm_fact = {'int16':INT16_FAC, 'int32':INT32_FAC, 'int64':INT64_FAC,'float32':1.0,'float64':1.0}

def wavread(filename):
    (fs, x) = read(filename)    # read a sound file and return an array with the sound and the sampling rate
    x = np.float32(x)/norm_fact[x.dtype.name]  #scaling down and converting audio into floating point number between range -1 to 1
    return fs, x


if __name__ == '__main__':
    (fs, xin) = wavread('test.wav')

    if (len(xin.shape) == 1):
     print('Mono files unsupported.')
     exit()

    x = xin[:,0]
    N = len(x)

    env1 = 0.0        # lowpass
    y1 = []
    for n in range(N):
      tmp1 = x[n]
      env1 = 0.95 * (env1 - tmp1) + tmp1
      y1.append (env1)

    H = abs(hilbert(y1))     # module of hilbert transform

    plot(range(N),H)
    show()