Method and apparatus for encoding/decoding audio data with scalability

The bitrate controllable audio encoding method, decoding method, encoding apparatus and decoding apparatus is disclosed. The step of encoding the sub information to the encoding method to enable the audio data bit rate control includes (c) for the first layer scale factor information and coding model information in accordance with the present invention; (F) the method comprising in the order of the least significant bit from the most significant bit with reference to the coding model information for a plurality of quantization samples corresponding to the first layer, the arithmetic coding to the N-bit unit from the low frequency in the order of higher frequency; And (g) increasing by the ordinal number added before every time the layers until the encoding of a plurality of layers a predetermined End 1 characterized in that it comprises the step of repeatedly performing the step (c) to (g) step and a (N is an integer greater than or equal to 1). As a result, the frequency resolution in the other hand to provide a more sophisticated FGS even with small amount of data configured similar to the transfer function of the ear of the person helps provide a good quality even at a lower layer.