Coding method, decoding method, and apparatuses, programs and recording media therefor

摘要

An object of the present invention is to achieve high coding efficiency for a companded signal sequence and reduce the amount of codes. A coding method according to the present invention includes an analysis step and a signal sequence transformation step. The analysis step is to check whether or not there is a number that is included in a particular range but does not occur in a second signal sequence (a number sequence that indicates the magnitude (magnitude relationship) of original signals) and output information that indicates the number that does not occur. The signal sequence transformation step is to output a transformed second signal sequence (which is formed by assigning new numbers to indicate the magnitudes of original signals (the magnitude relationship among original signals) excluding the magnitude of the original signal indicated by the number that does not occur and replacing the numbers in the second signal sequence with the newly assigned numbers) in the case where it is determined in the analysis step that there is a number that does not occur. The particular range is defined as a number that indicates a positive value having a minimum absolute value and a number that indicates a negative value having a minimum absolute value, for example.