Abstract: Provided is an audio encoding method. The audio encoding method includes: acquiring envelopes based on a predetermined sub-band for an audio spectrum; quantizing the envelopes based on the predetermined sub-band; and obtaining a difference value between quantized envelopes for adjacent sub-bands and lossless encoding a difference value of a current sub-band by using a difference value of a previous sub-band as a context. Accordingly, the number of bits required to encode envelope information of an audio spectrum may be reduced in a limited bit range, thereby increasing the number of bits required to encode an actual spectral component.

Abstract: Provided is a method and apparatus for encoding/decoding an audio signal. Sections which are not used to output noise components near important spectral components and sub-bands which are not used to output noise components, are determined to be encoded or decoded, so that the efficiency of encoding and decoding an audio signal increases, and sound quality can be improved using less bits.

Abstract: Provided is a method and apparatus for encoding or decoding a signal corresponding to a high frequency band in an audio signal. The method and apparatus for encoding a high frequency band detects and encodes frequency component(s) according to a pre-set criterion from a signal corresponding to a frequency band higher than a pre-set frequency and encodes energy value(s) of a signal to reconstruct band(s) in which the detected frequency component(s) are included. The method and apparatus for decoding a high frequency band decodes the signal by adjusting a signal to reconstruct a band in which important frequency component(s) are included by considering an energy value of the important frequency component(s). Accordingly, even though encoding or decoding is performed using a small number of bits, there is no degradation in sound quality of a signal corresponding to a high frequency band, and thus coding efficiency can be maximized.

Abstract: Provided is a method and apparatus for encoding/decoding an audio signal. Sections which are not used to output noise components near important spectral components and sub-bands which are not used to output noise components, are determined to be encoded or decoded, so that the efficiency of encoding and decoding an audio signal increases, and sound quality can be improved using less bits.

Abstract: A bit allocating method is provided that includes determining the allocated number of bits in decimal point units based on each frequency band so that a Signal-to-Noise Ratio (SNR) of a spectrum existing in a predetermined frequency band is maximized within a range of the allowable number of bits for a given frame; and adjusting the allocated number of bits based on each frequency band.

Abstract: Provided is a method and apparatus for encoding/decoding an audio signal. Sections which are not used to output noise components near important spectral components and sub-bands which are not used to output noise components, are determined to be encoded or decoded, so that the efficiency of encoding and decoding an audio signal increases, and sound quality can be improved using less bits.

Abstract: Encoding and decoding of an audio signal or a video signal. By performing entropy encoding and decoding based on a tree structure, coding efficiency is increased, complexity is reduced, and additional information can be reduced.

Abstract: A method and apparatus to quantize and dequantize an input signal, and a method and apparatus to encode and decode an input signal. The method of quantizing an input signal includes determining a quantization scale type according to a distribution feature of the input signal, and quantizing the input signal according to the determined quantization scale type. Accordingly, when a number of assigned bits is small in an encoding process, signal distortion can be minimized without an increase in complexity or having to use large sized additional information in order to determine an optimum scale. In addition, the input signal can be encoded by considering a trade-off of a distortion rate corresponding to the number of assigned bits of the input signal.

Abstract: A method and apparatus to encode and decode an audio signal. In the encoding method and apparatus, one or more important frequency components may be detected from an audio signal, the frequency components may be encoded, and then an envelope of the audio signal may be encoded. In the decoding method and apparatus, an audio signal may be decoded by adjusting envelopes at one or more bands containing one or more important frequency components in consideration of the energy values of the frequency components. Accordingly, it is possible to maximize the coding efficiency without degrading the sound quality of the audio signal even if the audio signal is encoded or decoded using a small amount of bits.

Abstract: Provided is a method and apparatus for encoding or decoding a signal corresponding to a high frequency band in an audio signal. The method and apparatus for encoding a high frequency band detects and encodes frequency component(s) according to a pre-set criterion from a signal corresponding to a frequency band higher than a pre-set frequency and encodes energy value(s) of a signal to reconstruct band(s) in which the detected frequency component(s) are included. The method and apparatus for decoding a high frequency band decodes the signal by adjusting a signal to reconstruct a band in which important frequency component(s) are included by considering an energy value of the important frequency component(s). Accordingly, even though encoding or decoding is performed using a small number of bits, there is no degradation in sound quality of a signal corresponding to a high frequency band, and thus coding efficiency can be maximized.

Abstract: Encoding and decoding of an audio signal or a video signal. By performing entropy encoding and decoding based on a tree structure, coding efficiency is increased, complexity is reduced, and additional information can be reduced.

Abstract: Provided is a method and apparatus for encoding/decoding an audio signal. Sections which are not used to output noise components near important spectral components and sub-bands which are not used to output noise components, are determined to be encoded or decoded, so that the efficiency of encoding and decoding an audio signal increases, and sound quality can be improved using less bits.

Abstract: A method and apparatus to quantize and dequantize an input signal, and a method and apparatus to encode and decode an input signal. The method of quantizing an input signal includes determining a quantization scale type according to a distribution feature of the input signal, and quantizing the input signal according to the determined quantization scale type. Accordingly, when a number of assigned bits is small in an encoding process, signal distortion can be minimized without an increase in complexity or having to use large sized additional information in order to determine an optimum scale. In addition, the input signal can be encoded by considering a trade-off of a distortion rate corresponding to the number of assigned bits of the input signal.

Abstract: A low-bitrate encoding system includes: a time-frequency transform unit transforming an input time-domain audio signal into a frequency-domain audio signal; a frequency component processor unit decimating frequency components in the frequency-domain audio signal; a psychoacoustic model unit modeling the received time-domain audio signal on the basis of human auditory characteristics, and calculating encoding bit allocation information; a quantizer unit quantizing the frequency-domain audio signal input from the frequency component processor unit to have a bitrate based on the encoding bit allocation information input from the psychoacoustic model unit; and a lossless encoder unit encoding the quantized audio signal losslessly, and outputting the encoded audio signal in a bitstream format. Using the low-bitrate encoding system, it is possible to effectively compress data at a low bitrate, and thus to provide a high quality audio signal.