<p>An apparatus encodes or decodes an audio signal using a method by which compatibility with a player of a general mono or stereo audio signal can be provided in coding an audio signal and by which spatial information for a multi-channel audio signal can be stored or transmitted without a presence of an auxiliary data area. The present invention includes extracting side information embedded in non-recognizable component of audio signal components and decoding the audio signal using the extracted side information.</p>
