A-law


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Related to A-law: Law society, u-Law

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]

A-Law

An ITU standard for converting analog data into digital form using pulse code modulation (PCM). A-Law uses a companding technique that provides more quantizing steps at lower amplitude (volume) than at higher amplitude. Europe uses A-Law, while North America and Japan use mu-Law (µ-Law). See PCM and mu-Law.
References in periodicals archive ?
711, A-law and u-law), although it can also operate at 56 kbps, or 48 kbps, and it is license free, and has better audio frequency response due to 16 kHz sampling and 14 bit resolution, and therefore G.
The WM8950 also supports A-law and u-law compounding for reduced data rates over a wireless link and an integrated PLL allows support for a wider range of clocking rates.
Different encoding formats like [micro]-law, A-law, 16 bit, and 13 bit PCM captures are supported (requires VBA038 License) and also it can process V.
MySoundStudio supports the widest range of file formats available, including WAV (cue point and loop), MP3, AIFF, Next/SUN (AU/SND) PCM, A-Law, mu-Law, ADPCM, 32bit IEEE float, 64bit IEEE float, Video for Windows, RAW and AVI.
For Bluetooth applications, AMBIN FM1072LP provides Serial Port supporting A-Law, u-Law, 13 bit Zero Padding, 13 bit Sign Extension, and 16 bit linear PCM.
The files are recorded in mu-law format for tProbe[TM] T1 and in A-law for tProbe[TM] E1.
A Bluetooth-compliant Synchronous Connection Oriented (SCO) codec incorporated in both ICs supports A-Law, micro-Law and 12-to-16 bit linear CVSD and SCO channel capabilities.
The chip includes complete micron-law and A-Law companders (pin selectable) that are designed to comply with industry specifications ITU-T G.
Kulkarni further added, “The enhancements introduced to Oscilloscope and Power Spectral Display applications include options for displaying all signaling formats - A-Law, Mu-Law, PCM 16 bit, PCM 13 bit, PCM 14 bit, PCM 8 bit and different byte order for INTEL (Little Endian) and MOTOROLA (Big Endian) 16 bit signals sampled at 16 KHz can also be displayed.