Patent ID: 8078475

Claim:
An audio signal decoder which decodes a first coded stream and outputs audio signals, comprising: a processor; an extraction unit configured to extract, from the first coded stream, a second coded stream representing at least one mixed signal having less than a plurality of pre-mixing audio signals mixed into the mixed signal, and to extract, from the first coded stream, supplementary information for reverting the mixed signal to the pre-mixing audio signals, said extraction unit using said processor to extract the second coded stream and the supplementary information; a decoding unit configured to decode the second coded stream representing the mixed signal; a signal separating unit configured to separate the mixed signal generated by said decoding unit based on the extracted supplementary information, and to generate a plurality of audio signals which are acoustically approximate to the plurality of pre-mixing audio signals; and a reproducing unit configured to reproduce the decoded mixed signal or the plurality of audio signals generated by said signal separating unit, wherein the supplementary information includes linear prediction coefficients for representing at least one of the plurality of pre-mixing audio signals as a function of the mixed signal, wherein said signal separating unit includes a no-correlation signal calculating unit configured to calculate a no-correlation signal representing, as a function of the mixed signal, a reference signal that is one of the plurality of pre-mixing audio signals by using the linear prediction coefficients in the supplementary information, wherein the supplementary information includes a flag indicating a degree of correlation between the plurality of pre-mixing audio signals, and wherein, in a case where the flag included in the supplementary information indicates that the plurality of pre-mixing audio signals have a low correlation, said signal separating unit is configured to generate the plurality of pre-mixing audio signals other than the reference signal by removing the no-correlation signal from the mixed signal.