Alaw
<standard> The ITUT standard for nonuniform quantising logarithmic compression.
The equation for Alaw is

A   (m/mp)
m/mp =< 1/A  1+ln A y =   sgn(m)   (1 + ln Am/mp)
1/A =< m/mp =< 1  1+ln A
Values of u=100 and 255, A=87.6, mp is the Peak message value, m is the current quantised message value.
(The formulae get simpler if you substitute x for m/mp and sgn(x) for sgn(m); then 1 <= x <= 1.)
Converting from uLAW to ALAW introduces quantising errors.
ulaw is used in North America and Japan, and Alaw is used in Europe and the rest of the world and international routes.
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