| 摘要 |
PURPOSE: A method and an apparatus for encoding or decoding an audio signal that is processed by using multiple subbands and overlapping window functions are provided to encode or decode the audio signal processed by using extended subband signal window switching configurations. CONSTITUTION: In MPEG-1 audio layer 3 following a 'window_switching_flag', the corresponding 2-bit value of 'block_type' is sent repeatedly although a decoder knows already from the occurrence of the parameter 'window_switching_flag' that a sequence of 'start block', 'short windows', 'stop block' and 'long window' will follow. Therefore, the changing parameter 'block_type' is redundant information. A superfluous parameter 'block_type' flag is not sent for block type signalling purposes. Instead, two corresponding bits are used for notifying the decoder of different subband signal window switching configuration types. The configuration types define how many subbands among the used total subbands are affected, or not affected by above parameter 'window_switching_flag'. These configuration types further define various subband groups fixed or variable within the total number of subbands, that are affected by the parameter 'window_switching_flag'.
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