#!/usr/bin/env python
# coding: utf-8

#   This software component is licensed by ST under BSD 3-Clause license,
#   the "License"; You may not use this file except in compliance with the
#   License. You may obtain a copy of the License at:
#                        https://opensource.org/licenses/BSD-3-Clause


"""KWS Feature Extraction example."""

import numpy as np
import librosa
import scipy
from scipy.signal import hann
from scipy.fftpack import dct


def mfcc_col(buff_test):

    window = 2048
    half_window = int(window / 2)
    n_mels = 128
    n_coeff = 13

    assert buff_test.shape == (window,)

    hann_asym_f32 = hann(window, sym=False).astype('float32')
    assert hann_asym_f32.shape == (window,), hann_asym_f32.shape

    buff_hann = buff_test * hann_asym_f32
    assert buff_hann.shape == (window,), buff_hann.shape

    fft = np.fft.fft(buff_hann, window)[:half_window + 1]
    assert fft.shape == (half_window + 1,), fft.shape

    ps = np.abs(fft)**2
    assert ps.shape == (half_window + 1,)

    mel = librosa.filters.mel(sr, window, n_mels)
    assert mel.shape == (n_mels, half_window + 1)

    energy = np.dot(mel, ps)
    assert energy.shape == (n_mels,)

    logamplitude = 10 * np.log10(energy)
    assert logamplitude.shape == (n_mels,)

    dct_out = dct(logamplitude, type=3)
    assert dct_out.shape == (n_mels,)

    return(dct_out[1:(n_coeff + 1)])


# buffer_bus_01 is made of first 2048 samples of "bus.wav" file
sr, ys = scipy.io.wavfile.read("bus.wav")

buffer_01 = ys[0:2048]

mfcc_col = mfcc_col(buffer_01)

print('mfcc = ', mfcc_col[:])