import scipy.io.wavfile as wavfile
import scipy
import scipy.fftpack
import numpy as np
from matplotlib import pyplot as plt

fs_rate, signal = wavfile.read("sound.wav")
START = 0
STOP = 4
signal = signal[START*fs_rate:STOP*fs_rate]
print ("Frequency sampling", fs_rate)
l_audio = len(signal.shape)
print ("Channels", l_audio)
if l_audio == 2:
    signal = signal.sum(axis=1) / 2
N = signal.shape[0]
print ("Complete Samplings N", N)
secs = N / float(fs_rate)
print ("secs", secs)
Ts = 1.0/fs_rate
print ("Timestep between samples Ts", Ts)
t = scipy.arange(0, secs, Ts)
FFT = abs(scipy.fft(signal))
FFT_side = FFT[range(N//2)]
freqs = scipy.fftpack.fftfreq(signal.size, t[1]-t[0])
fft_freqs = np.array(freqs)
freqs_side = freqs[range(N//2)]
fft_freqs_side = np.array(freqs_side)
plt.subplot(311)
p1 = plt.plot(t, signal, "g")
plt.xlabel('Time')
plt.ylabel('Amplitude')
plt.subplot(312)
p2 = plt.plot(freqs, FFT, "r")
plt.xlabel('Frequency (Hz)')
plt.ylabel('Count dbl-sided')
plt.subplot(313)
p3 = plt.plot(freqs_side, abs(FFT_side), "b")
plt.xlabel('Frequency (Hz)')
plt.ylabel('Count single-sided')
plt.tight_layout()
plt.show()