audio_processor.py

import librosa
import numpy as np


def compute_melgram(audio_path):
    ''' Compute a mel-spectrogram and returns it in a shape of (1,1,96,1366), where
    96 == #mel-bins and 1366 == #time frame

    parameters
    ----------
    audio_path: path for the audio file.
                Any format supported by audioread will work.
    More info: http://librosa.github.io/librosa/generated/librosa.core.load.html#librosa.core.load

    '''

    # mel-spectrogram parameters
    SR = 12000
    N_FFT = 512
    N_MELS = 96
    HOP_LEN = 256
    DURA = 29.12  # to make it 1366 frame..

    src, sr = librosa.load(audio_path, sr=SR)  # whole signal
    n_sample = src.shape[0]
    n_sample_fit = int(DURA*SR)

    if n_sample < n_sample_fit:  # if too short
        src = np.hstack((src, np.zeros((int(DURA*SR) - n_sample,))))
    elif n_sample > n_sample_fit:  # if too long
        src = src[(n_sample-n_sample_fit)/2:(n_sample+n_sample_fit)/2]
    logam = librosa.logamplitude
    melgram = librosa.feature.melspectrogram
    ret = logam(melgram(y=src, sr=SR, hop_length=HOP_LEN,
                        n_fft=N_FFT, n_mels=N_MELS)**2,
                ref_power=1.0)
    ret = ret[np.newaxis, np.newaxis, :]
    return ret