ENCODING METHOD, ENCODER AND RECORDING MEDIUM, AND DECODING METHOD, DECODER AND RECORDING MEDIUM

摘要

It has been very difficult to conduct real-time encoding and decoding, because the necessary quantity of arithmetical processing is very large when inputted image/voice data are encoded and when encoded image/voice data are decoded by a computer. The invention provides a 1st encoding method wherein signal form conversion, orthogonal conversion and variable length encoding are continuously carried out in units of predetermined small regions in a frame, and the frequency of memory access is reduced to thereby realize speed processing; a 2nd encoding method wherein the processing time is shortened by eliminating the orthogonal conversion calculation by using the coefficients subjected to the orthogonal conversion; and a 3rd encoding method wherein the number of registers which are used in the addition and substraction performed in the orthogonal conversion, etc. is reduced, and the frequency of memory access is decreased to realize high speed calculation. The invention also provides a decoding method wherein a table size is not large in variable length decoding, the maximum frequency of table access for one code word is two, and a plurality of code words are decoded by a single table access to realize high speed decoding.