Patent ID: 8428956

Claim:
A speech coding apparatus for encoding a stereo signal comprising a first single channel signal and a second single channel signal, the apparatus comprising: a monaural signal generator, comprising a processor, that generates a monaural signal using the first single channel signal and the second single channel signal; a selector, comprising a calculator that calculates a first parameter corresponding to the first single channel signal and a second parameter corresponding to the second single channel signal, the selector compares the first calculated parameter and the second calculated parameter to determine whether a criterion for implementing enhancement layer coding at high efficiency or high sound quality, based upon the comparison of the first calculated parameter and the second calculated parameter, is met, selects the first single channel signal if the criterion is met, and selects the second single channel signal if the criterion is not met; a coder that encodes the generated monaural signal to obtain core layer encoded data, and encodes the selected single channel signal to obtain enhancement layer encoded data corresponding to the core layer encoded data; and an outputter that outputs encoded data so that the encoded data is transmitted to speech decoding apparatus, wherein: the enhancement layer encoded data do not contain encoded data of an unselected single channel signal; and the encoded data includes selection information that represents which of the single channel signals the selector selected, the core layer encoded data and the enhancement layer encoded data.