Patent ID: 7979148

Claim:
An audio signal encoding apparatus comprising: means for converting first multiple-channel digital audio signals into audio signals of stereophonic 2 channels through down mixing; means for implementing matrix operation among the first multiple-channel digital audio signals to generate second multiple-channel audio signals correlating with each other, the first multiple-channel digital audio signals relating to a sampling frequency and a quantization bit number, the second multiple-channel audio signals lacking 2 channels corresponding to the stereophonic 2 channels; means for compressing the stereophonic 2-channel audio signals and the second multiple-channel digital audio signals into compression-resultant multiple-channel signals respectively, the compression-resultant multiple-channel signals relating to a smallest prediction-error basis lossless compression; and means for formatting the compression-resultant multiple-channel signals into a formatting-resultant signal, the formatting-resultant signal containing an access unit composed of a sub packet and a sync information portion, the sub packet containing at least portions of the compression-resultant multiple-channel signals, the sync information portion containing the signal representative of the sampling frequency and the signal representative of the quantization bit number, wherein said access unit is of variable length and said compression-resultant multiple-channel signals are compressed with a variable bit rate.