Variable length coding unit and variable length decoding unit

Abstract

A variable length encoding unit includes a run-length converter, a table memory, and a variable length encoder. The run-length converter converts block data consisting of a plurality of image signals into a zero-run number and a level value in accordance with a scanning sequence. The table memory stores a VLC (variable length code) and VLC length at an address corresponding to the zero-run number and level value. The variable length encoder reads the VLC and the VLC length from the table memory in response to the zero-run number and level value converted by the run-length converter, and carries out the variable length coding by cutting the VLC from the read data in accordance with the VLC length. The variable length coding unit can flexibly handle various types of variable length coding/decoding schemes including international standard coding methods without insisting on its unique variable length coding.