Encoding method and device, and decoding method and device

摘要

In an encoding apparatus (10), a code table group exchange judgment unit (12) selects a group of code tables from a plurality of groups of code tables according to the property such as tonality of a spectrum signal D11, and a quantization unit (15) encodes quantization coefficients using a code table included in the selected group. Then, a multiplexer (18) multiplexes a group index D12 together with coefficient data D 17. Furthermore, in case resources for an encoder is small, and sound quality may have to be somewhat degraded so as to realize practical encoding speed, a code table number change judgment unit (17) changes or reduces the number of code tables to be used.