Coding method, decoding method, apparatus, program, and recording medium

Abstract

A normalization value calculatorcalculates a normalization value that is representative of a predetermined number of input samples. A normalization value quantizerquantizes the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value. An quantization-candidate calculatorsubtracts a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, sets the difference value as an quantization candidate corresponding to the sample. When the difference value is positive and the value of each of the samples is negative, the quantization-candidate calculatorreverses the sign of the difference value and setting the sign-reversed value as an quantization candidate corresponding to the sample. When the difference value is not positive, the quantization-candidate calculatorsets 0 as an quantization candidate corresponding to the sample. A vector quantizerjointly vector-quantizes a plurality of quantization candidates corresponding to a plurality of samples to obtain a vector quantization index.