Home Articles FAQs XREF Games Software Instant Books BBS About FOLDOC RFCs Feedback Sitemap


You are here: irt.org | FOLDOC | A-law

<standard> The ITU-T standard for nonuniform quantising logarithmic compression.

The equation for A-law is

      |    A
      | ------- (m/mp)                   |m/mp| =< 1/A
      | 1+ln A
  y = |
      | sgn(m)
      | ------ (1 + ln A|m/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 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.

[The Audio File Formats FAQ]


Nearby terms: Alan Shugart « Alan Turing « ALARP « A-law » ALC » Alcool-90 » ALCOR

FOLDOC, Topics, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, ?, ALL

©2018 Martin Webb