ENCODING DEVICE, ENCODING METHOD, PROGRAM AND RECORDING MEDIUM

摘要

A gain codebook having a plurality of sets stored therein is stored in a gain quantization unit. The sets contain candidates for quantized fixed codebook gains, candidates for quantized pitch gains, and indexes. A plurality of indexes includes indexes with different numbers of bits. Time or frequency intervals are constituted by a plurality of sub-intervals, and for each sub-interval, an index, which is selected by considering both waveform distortion itself caused by gain quantization and the distortion converted from the length of the corresponding code, serves as a gain code. An encoding method is adjusted in at least one sub-interval in which subsequent processing is performed on the basis of the length of the selected gain code.