Computer Dictionary/A-law

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The ITU-T standard for [[Computer Dictionary/nonuniform quantising

logarithmic compression|nonuniform quantising logarithmic compression]].

The equation for A-law is

     |    A
     | ------- (m/mp)                   |m/mp| =[[Category:Computer Dictionary/ 1/A
     | 1+ln A
 y = |
     | sgn(m)
     | ------ (1 + ln A|m/mp|)   1/A =[[Category:Computer Dictionary/ |m/mp| =[[Category:Computer Dictionary/ 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 [[Category:Computer Dictionary/= x [[Category:Computer Dictionary/= 1.)

Converting from u-LAW to A-LAW introduces [[Computer Dictionary/quantising errors|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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