Low bitrate decoding/encoding method and apparatus

The present invention relates to a low bit rate encoding / decoding method and apparatus, low-bit-rate encoder, the time / frequency converter for converting the audio signal in the time domain input to the audio signal in the frequency domain; Frequency component processing section that reduces the frequency coefficients of the audio signal from the audio signal in the frequency domain; To the audio signal in the time domain it is accepted model to match the human auditory characteristics, and calculating encoding bit allocation information, the psychoacoustic model unit; A quantization unit for quantizing by assigning a number of bits depending on the encoding bit allocation information to the audio signal applied through the frequency component processing section is applied from the psychoacoustic model unit; And a quantized audio signal to lossless encoding is composed of a lossless encoding and outputting a bitstream. Accordingly, it is possible to provide a high sound quality by efficiently compress data at a low bit rate.