Timbral_Metallic.py 文件源码

def get_spectral_features(audio, fs, lf_limit=20):
    """
     This function calculates the spectral centroid and spectral spread of an audio array.

     :param audio:      Audio array 
     :param fs:         Sample rate of audio file
     :param lf_limit:   Low frequency limit, in Hz, to be analysed.  Defaults to 20Hz.
     :return:           Returns the spectral centroid and spectral spread
    """
    # use a hanning window
    window = np.hanning(len(audio))
    next_pow_2 = int(pow(2, np.ceil(np.log2(len(window)))))
    # get frequency domain representation
    spectrum = np.fft.fft((window * audio), next_pow_2)
    spectrum = np.absolute(spectrum[0:int(len(spectrum) / 2) + 1])
    freq = np.arange(0, len(spectrum), 1) * (fs / (2.0 * (len(spectrum) - 1)))

    # find lowest frequency index, zeros used to unpack result
    lf_limit_idx = np.where(freq >= lf_limit)[0][0]
    spectrum = spectrum[lf_limit_idx:]
    freq = freq[lf_limit_idx:]

    # calculate centroid and spread
    centroid = sum(spectrum * freq) / float(sum(spectrum))
    spread = np.sqrt(sum(((freq - centroid) ** 2) * spectrum) / sum(spectrum))

    return centroid, spread