Method of and apparatus for encoding and decoding digital video signals by representing orthogonal transform coefficients with respective group values

摘要

Digital signals representing a video image are variable length encoded and decoded by representing a sequence of orthogonal transformation coefficients with respective group numbers that represent groups of values of zero run lengths or groups of values of effective AC coefficients within the sequence. Huffman code values are assigned for each effective AC coefficient or for each zero run length by referencing a set of Huffman coding tables in which the Huffman code values are stored according to the respective group number and its immediately preceding group number in the sequence. The most frequent group numbers are assigned the shortest length Huffman code values and the least frequent group numbers are assigned the greatest length Huffman code values.