Variable-length encoded data decoding apparatus and decoding method

A variable-length encoded data decoding method, comprising:

• classifying codewords, whose bit lengths exclusive of common bit patterns on MSB sides are equal to or less than a predetermined value, among used codewords into groups in correspondence with the respective common bit patterns;
• generating a common bit pattern length table for storing bit lengths of the common bit patterns that respectively correspond to the groups;
• generating a decoding table for storing a bit length and decoded data of a codeword in correspondence with the codeword within each of the groups;
• and
• decoding input encoded data by using the common bit pattern length table, and the decoding table.

A program used by a computer decoding variable-length encoded data, causing the computer to execute a process, the process comprising:

• classifying codewords, whose bit lengths exclusive of common bit patterns on MSB sides are equal to or less than a predetermined value, among used codewords into groups in correspondence with the respective common bit patterns;
• generating a common bit pattern length table for storing bit lengths of the common bit patterns that respectively correspond to the groups, and a decoding table for storing a bit length and decoded data of a codeword in correspondence with the codeword within each of the groups;
• and
• decoding input encoded data by using the common bit pattern length table, and the decoding table.

A computer-readable portable storage medium used by a computer decoding variable-length encoded data, on which is recorded a program for causing the computer to execute a process, the process comprising:

• classifying codewords, whose bit lengths exclusive of common bit patterns on MSB sides are equal to or less than a predetermined value, among used codewords into groups in correspondence with the respective common bit patterns;
• generating a common bit pattern length table for storing bit lengths of the common bit patterns that respectively correspond to the groups, and a decoding table for storing a bit length and decoded data of a codeword in correspondence with the codeword within each of the groups;
• and
• decoding input encoded data by using the common bit pattern length table, and the decoding table.