estimation.py 文件源码

def pitch_strength_one_candidate(f_erbs, nL, pc):
    """
    Calculates the pitch ``strength'' for a single
    candidate

    Args:
        f_erbs (array):
        nL           : normalized loudness
        pc           : pitch candidate

    Returns:
        s     (float): value of strength for a pitch
    """

    # fix rounds a number *towards* zero
    n = int(np.fix(f_erbs[-1] / pc - 0.75))  # number of harmonics
    if n == 0:
        return np.nan
    k = np.zeros(f_erbs.shape)  # kernel

    # normalize freq w.r.t. candidate
    q = f_erbs / pc

    # create kernel
    primes = np.concatenate((np.ones(1), primes_2_to_n(n)))
    for i in primes:
        a = np.abs(q - i)

        # peak's weight
        p = a < 0.25
        k[p] = np.cos(2 * np.pi * q[p])

        # valley's weight
        v = np.logical_and(0.25 < a, a < 0.75)
        k[v] = k[v] + np.cos(2 * np.pi * q[v]) / 2

    # apply envelope
    k = k * np.sqrt(1 / f_erbs)

    # K+-normalized kernel
    k = k / np.linalg.norm(k[k>0])

    # strength value of pitch
    s = np.dot(k, nL)

    return s