Patent ID: 6026198
Filing Date: 2000-02-15
Classification: G06T,H03M

Abstract:
A data compression system for encoding an input character on the basis of a conditional appearance rate relative to a context of each order orderly from a high-order context that is an immediately preceding long character string to a low-order context that is an immediately preceding short character string, comprising:a plurality of occurrence frequency modeling units, associated with orders, each having a frequency data storage unit in which the conditional appearance rate of an input character to be linked to an immediately preceding character string is registered for each character relative to a context of each order, and operating in parallel with the other modeling units to retrieve the conditional appearance rate of an input character to be linked to an immediately preceding character string that is a context of each order, and to update the contents of said frequency data storage unit; andan entropy coding unit to encode an input character on the basis of a conditional appearance rate relative to a context of each order, which is obtained by each of said plurality of occurrence frequency modeling units, orderly from a large-order context to a small-order context; anda pipeline control unit to enable said plurality of occurrence frequency modeling units and said entropy coding unit to operate in pipelining,wherein said pipeline control unit repeats processes such that, at a first cycle, a head character of an input character string is inputted to said plurality of occurrence frequency modeling units in parallel and a conditional appearance rate of each order is obtained in parallel and, at second and, subsequent cycles, the conditional appearance rate of each order obtained at the first cycle is outputted to said entropy coding unit and is sequentially arithmetically encoded in accordance with the order from the code of the large-order context to the code of the small-order context, a next character of said input character string is inputted to said plurality of occurrence frequency modeling units, and the occurrence frequency of each order is obtained in parallel.