spectral.py 文件源码

def power_to_db(spectrum: np.ndarray,
                clip_below: float = None,
                clip_above: float = None) -> np.ndarray:
    """
    Convert a spectrogram to the Decibel scale.

    Optionally, frequencies with amplitudes below or above a certain threshold can be clipped.

    Parameters
    ----------
    spectrum: numpy.ndarray
        The spectrogram to convert
    clip_below: float, optional
        Clip frequencies below the specified amplitude in dB
    clip_above: float, optional
        Clip frequencies above the specified amplitude in dB

    Returns
    -------
    numpy.ndarray
        The spectrogram on the Decibel scale
    """
    # there might be zeros, fix them to the lowest non-zero power in the spectrogram
    epsilon = np.min(spectrum[np.where(spectrum > 0)])

    sxx = np.where(spectrum > epsilon, spectrum, epsilon)
    sxx = 10 * np.log10(sxx / np.max(sxx))

    if clip_below is not None:
        sxx = np.maximum(sxx, clip_below)

    if clip_above is not None:
        sxx = np.minimum(sxx, clip_above)

    return sxx