def spectral_flux(d0, d1):
    """
    Computes the spectral flux feature of the current frame
    """
    # compute the spectral flux as the sum of square distances:
    d0 = np.mean(d0, axis=1)
    d1 = np.mean(d1, axis=1)
    nFFT = min(len(d0) // 2, len(d1) // 2)
    X = FFT(d0, nFFT)
    Xprev = FFT(d1, nFFT)

    # L = min(len(X), len(Xprev))

    sumX = np.sum(X + EPSILON)
    sumPrevX = np.sum(Xprev + EPSILON)
    return np.sum((X / sumX - Xprev / sumPrevX) ** 2)
Computes the spectral flux feature of the current frame