Patent ID: 6215906
Filing Date: 2001-04-10
Classification: G06T,H03M

Abstract:
A data compression system for encoding an input character on the basis of a conditional appearance rate obtained in relation to an immediately preceding character string, comprising:an occurrence frequency modeling unit 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, retrieving the conditional appearance rate of an input character to be linked to an immediately preceding character string by referencing said frequency data storage unit, and updating the contents of said frequency data storage unit;an entropy coding unit for encoding an input character according to a conditional appearance rate obtained from said occurrence frequency modeling unit; anda pipeline control unit for enabling said occurrence frequency modeling unit and entropy coding unit to operate in pipelining,wherein said pipeline control unit repeats processes such that, at a first cycle, a head character of the input character string is inputted to said occurrence frequency modeling unit and the conditional appearance rate of said input character is obtained and, at each cycle after a second cycle, a next character of said character string is inputted to said occurrence frequency modeling unit, a conditional appearance rate of said input character is obtained, the conditional appearance rate of the character obtained at a previous cycle is inputted to said entropy coding unit, and the occurrence frequency of said input character is encoded.