batchdispenser.py 文件源码

def apply_cmvn(utt, mean, variance, reverse=False):
    """Apply mean and variance normalisation based on previously computed statistics.

    Args:
        utt: The utterance feature numpy matrix.
        stats: A numpy array containing the mean and variance statistics.
            The first row contains the sum of all the fautures and as a last
            element the total numbe of features. The second row contains the
            squared sum of the features and a zero at the end

    Returns:
        A numpy array containing the mean and variance normalized features
    """
    if not reverse:
        #return mean and variance normalised utterance
        return np.divide(np.subtract(utt, mean), np.sqrt(variance))
    else:
        #reversed normalization
        return np.add(np.multiply(utt, np.sqrt(variance)), mean)