Method and device for decoding an audio signal that has a base layer and an enhancement layer

The invention claims with a substrate layer part and a level part the audio signal lock and decoding method. The audio signal to be with BL and EL, EL expression is opposite BL audio content of additional information. The decoding of a double-layer signal typically comprises a BL data the decoding (21), recovery (22) via frequency band, a frequency band a returning maps (23) is formed on the MDCT domain, the EL adding of a frequency band and decoding a map, and executing counter is MDCT. The invention further provided with a complexity decoding method, comprising: Decoding to the EL data and a counter maps (45), and a (42) is the EL BL data of data part and decoding of a mapping, and is the counter BL filter device for and method for filter.