A-law coding/decoding

The A-law coding/decoding table for positive and negative values are given in tab. 1. The coding law is:

Positive values:

• 127 decision values are used (n = 128 is a virtual decision)
• x between decision values [x(n),x(n+1)] is coded as 128+n before the even bit inversion
• the decoder output value will then be:

  y(n)=[x(n-1)+x(n)]/2 for n=1,...,128

Tab. 1a - A-law positive value coding/decoding table.

a)

Negative values:

• 127 decision values are used (n = 128 is a virtual decision)
• x between decision values [x(n),x(n+1)] is coded as n before the even bit inversion
• the decoder output value will then be:

  y(n)=[x(n-1)+x(n)]/2 for n=1,...,128

Tab. 1b - A-law negaitive value coding/decoding table.

b)

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