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An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, ''i.e.,'' modify, the dynamic range of an analog signal for digitizing. It is similar to the μ-law algorithm used in North America and Japan. For a given input ''x'', the equation for A-law encoding is as follows, : where ''A'' is the compression parameter. In Europe, . A-law expansion is given by the inverse function, : The reason for this encoding is that the wide dynamic range of speech does not lend itself well to efficient linear digital encoding. A-law encoding effectively reduces the dynamic range of the signal, thereby increasing the coding efficiency and resulting in a signal-to-distortion ratio that is superior to that obtained by linear encoding for a given number of bits. == Comparison to μ-law == The μ-law algorithm provides a greater larger dynamic range than the A-law at the cost of worse proportional distortion for small signals. By convention, A-law is used for an international connection if at least one country uses it. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「A-law algorithm」の詳細全文を読む スポンサード リンク
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