Reference channel adaptation method considering subband spatial cues for multi-channel audio signal

A method of applying a variable reference channel to a multi-channel audio signal using spatial information of each sub-band is provided to represent a spatial information bit stream in an efficient manner using a variable reference channel for spatial information in consideration of characteristics of the multi-channel audio signal to improve encoding, transmission and decoding efficiency of the multi-channel audio signal. A multi-channel audio signal is down-mixed and spatial information of the multi-channel audio signal is extracted by sub-bands(315,316). Reference channels are set for respective sub-bands using the spatial information, and spatial information of the other channels is re-extracted using spatial information of the set reference channels(318). The entire bit stream is constructed using the down-mixed audio signal and the re-extracted spatial information(321).