shithub: opus

ref: 87cd75f6f4a5ad6c113f4c58f91acfc0e3369009
dir: /dnn/ulaw.py/

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import numpy as np
import math

def ulaw2lin(u):
    s = np.sign(u)
    u = np.abs(u)
    return s*(np.exp(u/128.*math.log(256))-1)/255


def lin2ulaw(x):
    s = np.sign(x)
    x = np.abs(x)
    u = (s*(128*np.log(1+255*x)/math.log(256)))
    u = np.round(u)
    return u.astype('int16')