Abstract: A method and apparatus for shaping quantization noise generated when compressing audio data at a low bit rate is disclosed. A predetermined quantization noise threshold allowed during quantization of sampled audio data and quantization noise energy information of a quantized MDCT coefficient are received in all frequency bands of an audio frequency. The quantization noise energy of the quantized MDCT coefficient is attenuated in a predetermined number of frequency bands in which a difference between the predetermined quantization noise threshold and the quantization noise energy of the quantized MDCT coefficient is large.

Abstract: A method and apparatus for shaping quantization noise generated when compressing audio data at a low bit rate is disclosed. A predetermined quantization noise threshold allowed during quantization of sampled audio data and quantization noise energy information of a quantized MDCT coefficient are received in all frequency bands of an audio frequency. The quantization noise energy of the quantized MDCT coefficient is attenuated in a predetermined number of frequency bands in which a difference between the predetermined quantization noise threshold and the quantization noise energy of the quantized MDCT coefficient is large.

Abstract: An apparatus and method for encoding audio data with a small amount of computation are provided. The audio data encoding apparatus includes: a time-to-frequency converting unit that receives a time domain audio signal and converts the same to a frequency domain audio signal; a spectral processor that performs spectral processing on the frequency domain audio signal; a masking threshold calculator that calculates an energy level for each frequency band of the frequency domain audio signal, approximates an energy distribution curve connecting the calculated energy levels to a distribution pattern similar to that of noise threshold levels calculated by a conventional psychoacoustic model, and calculates a scalefactor band gain for each band; and a quantization noise curve adjuster that adjusts a common gain to meet a target bit rate and matches a quantization noise curve to the approximated energy distribution curve while fixing the scalefactor gain for each frequency band.

Abstract: An improved Huffman decoding method and an apparatus thereof are provided. The method includes (a) obtaining index information from a first bit of a codeword formed with bits of a part of a received encoded bit stream, and accessing an entry of the look-up table corresponding to the obtained index information, and (b) determining a type of the entry based on an internal value of the accessed entry.

Abstract: An improved Huffman decoding method and an apparatus thereof are provided. The method includes (a) obtaining index information from a first bit of a codeword formed with bits of a part of a received encoded bit stream, and accessing an entry of the look-up table corresponding to the obtained index information, and (b) determining a type of the entry based on an internal value of the accessed entry.