layers.py 文件源码

def mu_law_encode_nonlinear(audio, quantization_channels=256):
    '''
    Compress the waveform amplitudes using mu-law non-linearity. 
    NOTE: This mu-law functions as a non-linear function as opposed to 
          quantization.
    '''
    with tf.name_scope('encode'):
        mu = tf.to_float(quantization_channels - 1)
        # Perform mu-law companding transformation (ITU-T, 1988).
        # Minimum operation is here to deal with rare large amplitudes caused
        # by resampling.
        safe_audio_abs = tf.minimum(tf.abs(audio), 1.0)
        magnitude = tf.log1p(mu * safe_audio_abs) / tf.log1p(mu)
        signal = tf.multiply(tf.sign(audio), magnitude, name='mulaw')
        # Quantize signal to the specified number of levels.
        # return tf.to_int32((signal + 1) / 2 * mu + 0.5)
        return signal