Patent ID: 7299174

Claim:
A speech coding apparatus comprising: a base layer coder that codes an input signal and generates first coded information; a base layer decoder that decodes the first coded information and generates a first decoded signal, while generating long term prediction information comprising information representing long term correlation of speech or sound; an adder that obtains a residual signal representing a difference between the input signal and the first decoded signal; and an enhancement layer coder that calculates a long term prediction coefficient using long term prediction information and the residual signal, and codes the long term prediction coefficient and generates second coded information, wherein the enhancement layer coder comprises: an obtainer that obtains a long term prediction lag of an enhancement layer based on long term prediction information; a fetcher that fetches a long term prediction signal back by the long term prediction lag from a previous long term prediction signal sequence stored in a buffer; a first calculator that calculates the long term prediction coefficient using the residual signal and the long term prediction signal; a coder that codes the long term prediction coefficient and generates enhancement layer coded information; a decoder that decodes enhancement layer coded information and generates a decoded long term prediction coefficient; and a second calculator that calculates a new long term prediction signal using the decoded long term prediction coefficient and the long term prediction signal, and updates the buffer using the new long term prediction signal.