A-law definition standard
The ITU-T standard
for nonuniform quantising logarithmic compression.
The equation for A-law is
| A | ------- (m/mp) |m/mp| =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 Converting from u-LAW to A-LAW introduces quantising errors. u-law is used in North America and Japan, and A-law is used in Europe and the rest of the world and international routes.
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