What are Mu-law and A-law?
• Mu-law and A-law are audio compression schemes (CODECs) defined by CCITT G.711 which compress 16 bit linear PCM data down to 8 bits of logarithmic data. In the encoding process (often referred to logarithmic companding) breaks the PCM data into segments with each progressively higher segment doubling in size. This ensures that the lower amplitude signals (where most of the information is speech takes place) get the highest bit resolution while still allowing enough dynamic range to encode high amplitude signals. Though this method doesn’t provide a very high compression ratio (roughly 2:1), it doesn’t require much processing power to decode. Mu-law (also written uLaw, since the ‘mu’ in question is actually supposed to be a Greek symbol resembling a lower case u) is the encoding scheme used for North America and Japan for voice data traffic and many PBX and IVR systems and much internet radio (via MIME). A-Law (or aLaw) is used in Europe and throughout the rest of the world.
