Patent ID: 7830921

Claim:
A method of processing an audio signal by an encoder, the method comprising: independently subdividing, by the encoder, at least first and second channels in a frame of the audio signal into blocks if the first and second channels are not correlated with each other; synchronously subdividing, by the encoder, the first and second channels into blocks such that lengths of the blocks into which the second channel is subdivided correspond to lengths of the blocks into which the first channel is subdivided if the first and second channels are correlated with each other and difference coding is used; generating, by the encoder, first information indicating whether the first and second channels are independently subdivided or synchronously subdivided; and generating, by the encoder, second information indicating a number of levels in a subdivision hierarchy, wherein both the independently subdividing step and the synchronously subdividing step subdivide the first and second channels according to the subdivision hierarchy, the subdivision hierarchy has more than one level, and at least two of the blocks in each of the first and second channels for each level have different lengths, wherein the second information indicates whether the subdivision hierarchy includes one of up to three levels, four levels, and five levels, if the second information is 01, the second information indicates the subdivision hierarchy includes up to three levels, if the second information is 10, the second information indicates the subdivision hierarchy includes four levels, and if the second information is 11, the second information indicates the subdivision hierarchy includes five levels.