Apparatus for variable-length coding and variable-length-decoding using a plurality of Huffman coding tables

摘要

An apparatus for variable-length-coding input symbols using a plurality of variable-length-code tables includes N variable-length-code tables each having a symbol-codeword association different from the others according to statistics regarding the symbols and a variable- length-coding device for coding the input symbols according to each of the variable-length-code tables for every block in a predetermined block data unit, for generating codewords, and for providing both table information representing each of the variable-length-code tables utilized in generating the respective codewords and a control signal indicating that variable-length-coding to a predetermined block data unit has been completed. The apparatus also includes buffers which store the codewords generated by the variable-length-coding device, an optimum table determining device receiving the output codewords for controlling the buffer so as to output codewords with a minimum amount of data for the block data unit, for supplying the table information from the variable- length-coding device and for providing table selection information representing a variable-length-code table producing the minimum amount of data for an input block data unit. The apparatus further includes a first switching circuit which receives table selection information and codewords and respectively outputs data in response to the output control signal. The apparatus advantageously can improve data compression efficiency. A complementary decoder, which can be used in building a communication system, is also described.