Mu-law algorithm

The mu-law algorithm, also written mu-law or u-law, is a companding algorithm used mainly in eight-bit pulse-code-modulation digital telecommunications systems in North America and Japan. It is one of the two companding algorithms in the ITU-T G.711 standard, the other being the similar A-law, which is used where digital telecommunication signals are carried on E-1 circuits, for example in Europe. Companding reduces the dynamic range of an audio signal; in analog systems this can raise the signal-to-noise ratio, and in the digital domain it reduces quantization error, a gain that can be traded for lower bandwidth. At the cost of a lower peak signal-to-noise ratio, the non-linear quantization of mu-law effectively increases dynamic range by 33 dB, so that a 14-bit input signal can be compressed into eight bits.