Abstract: Provided are a methods and apparatuses for encoding/decoding an audio signal to efficiently encode/decode a harmonic envelope. The method of encoding an audio signal includes performing harmonic analysis with respect to an input signal to determine harmonic parameters with respect to harmonic signals; correlating the amplitudes of the harmonic signals to signals in a time domain instead of signals in a frequency domain; applying a time-frequency transformation operation to the amplitudes in the time domain to generate time-frequency transformed values in the frequency domain; and encoding the time-frequency transformed values. When expressing a harmonic envelope, the amplitudes of the harmonic signals are regarded as signals in the time domain so as to perform a time-frequency transformation and only a part from among the transformed values is selected to be encoded. Therefore, sound quality is not affected and coding efficiency greatly improves.

Abstract: Methods and apparatuses for encoding and decoding of an audio signal using a mixture of a time-frequency method and a parametric method according to the audio band are provided. An encoding method of an audio signal includes: dividing input audio signals into a plurality of audio bands; selecting a coding method for each audio band; encoding each audio band according to the selected coding method for each band; and generating a bit stream including all the data encoded for each audio band, wherein selecting a coding method for each band comprises selecting smaller encoded data either from a parametric coding method or a time frequency coding method.

Abstract: A method and apparatus for decoding a parametric-encoded audio signal are provided. According to the present invention, parameters extracted from a bitstream of a parametric encoded audio signal are adjusted by a user and component signals are synthesized based on the adjusted parameters to be displayed to a user so that a user can adjust the amplitudes of the component signals to apply various sound effects according to the user's desire. In addition, since an equalizer function is embodied in a codec of an audio reproduction apparatus, additional equalizer modules are not required and thus complexity of the audio reproduction apparatus can be reduced.

Abstract: A method and apparatus for encoding a multi-channel audio signal is provided. The method includes the operations of selecting a first variable length code table (VLC) that is to be used to encode the multi-channel audio signal in a given frequency band, from among a plurality of VLC tables, and encoding the multi-channel audio signal by using the first VLC table. Thus, the multi-channel audio signal can be encoded by using VLC tables that differ according to frequency bands.

Abstract: Provided are a method and apparatus for encoding/decoding stereo audio. In the method for encoding stereo audio, stereo audio is encoded based on at least one of the phase difference between first and second channel audios and information on an angle made by a vector on the intensity of mono-audio and a vector on the intensity of the first channel audio or a vector on the intensity of the second channel audio. Thus, the number of encoded parameters is minimized so that a compression ratio in the encoding of the stereo audio is improved.

Abstract: Provided are a method and apparatus for encoding or decoding an audio signal by adaptively interpolating a linear predictive coding (LPC) coefficient. In the method and apparatus of encoding or decoding an audio signal, LPC coefficient interpolation is selectively performed depending on whether a transient section is present in a current frame, thereby preventing noise from occurring when interpolating LPC coefficients in the transient section.

Abstract: Provided are a method and apparatus for encoding the frequency of a continuation sinusoidal signal and a method and apparatus for decoding the same. In the encoding method, a continuation sinusoidal signal successive to a sinusoidal signal in a previous section is extracted from a current section; a frequency of the continuation sinusoidal signal at the boundary between the current and previous sections is changed to a first frequency, based on representative frequencies of the continuation sinusoidal signal and at least one sinusoidal signal that belongs to a section adjacent to the current section and is successive to the continuation sinusoidal signal; and the first frequency is encoded.

Abstract: Encoding and decoding of residual signals are provided. In a method of encoding a residual signal of an audio signal, the residual signal is divided into a plurality of sections having different sizes, based on a change of the residual signal. Then, section division information representing information about the divided sections and section-by-section residual signal information representing characteristics of the sections of the residual signal are acquired. Thereafter, the residual signal is encoded based on the section division information and the section-by-section residual signal information.

Abstract: Provided are methods and apparatuses for more efficiently encoding and decoding a high frequency band signal which is from an audio signal and which is greater than a predetermined threshold frequency. The method and apparatus for encoding the audio signal encodes a linear prediction coding (LPC) coefficient and gain information of a residual signal, which are generated by performing LPC analysis, thereby encoding a high frequency signal so as to have enhanced sound quality, while using less bits.

Abstract: Provided are a method and apparatus for effectively encoding/decoding remaining difference signals excluding sinusoidal components, from input audio signals. In the method and apparatus for encoding audio signals, sinusoidal analysis is performed on low frequency signals of less than a predetermined critical frequency in order to extract sinusoidal signals and then, an encoding operation is performed on the remaining difference signals excluding the sinusoidal signals, from input audio signals, by using linear prediction coding (LPC) analysis.

Abstract: Provided are a method of adaptively determining a quantization step according to a masking effect in a psychoacoustics model and a method of encoding/decoding an audio signal by using the determined quantization step. The method of adaptively determining a quantization step includes calculating a first ratio value indicating an intensity of an input audio signal with respect to a masking threshold; and determining the maximum value of the quantization step in a range in which noise generated when the audio signal is quantized is masked, according to the first ratio value. According to the present invention, quantization noise may be removed and the number of bits required to encode an audio signal may be reduced, by using auditory characteristics of humans.

Abstract: Provided are a method and apparatus for encoding/decoding a media signal. The method of encoding a media signal includes: when harmonics exist in a sinusoid of a previous frame section, predicting a harmonic frequency of a current frame section that is to be encoded by using a harmonic frequency of the previous frame section, and generating a residual signal by using a difference between the predicted frequency and an actual harmonic frequency of the current frame section.

Abstract: A method and apparatus for encoding/decoding a media signal. The method of decoding a media signal includes extracting first table index information from a header. The first table index information indicates M (M<N) tables substantially referred to by frames from among N tables which can be referred to for performing an operation performed by the frames, wherein N and M are natural numbers. Second table index information is then extracted from each frame. The second table index information indicates tables referred to by each frame from among M tables. The tables, which are referred to by the frames, are then identified by using the first and second table index information and the frames are decoded by referring to identified tables.

Abstract: Provided are an audio signal encoding method and apparatus that encode a continuation sinusoidal signal of a current frame in different ways according to information on a sinusoidal signal of a previous frame by using the characteristics of the continuation sinusoidal signal, and an audio signal decoding method and apparatus. The audio signal encoding method includes extracting a sinusoidal signal of a current frame by performing sinusoidal analysis on an input audio signal; extracting a continuation sinusoidal signal of the current frame, which is connected to a sinusoidal signal of a previous frame, by performing sinusoidal tracking of the extracted sinusoidal signal of the current frame; and encoding the continuation sinusoidal signal in different ways by using information on the sinusoidal signal of the previous frame, which is connected to the continuation sinusoidal signal.

Abstract: Provided are parametric audio encoding and decoding apparatuses and methods thereof. In the parametric audio encoding method, an audio signal is segmented into a plurality of segments. At least one sine wave is extracted from each of the segments, and the extracted sine waves are connected. It is determined whether an extracted sine wave is a birth sine wave. If the extracted sine wave is a birth sine wave, a bit stream is generated by encoding the phase of the birth sine wave on the basis of the frequency of the birth sine wave, wherein the number of bits allocated to encode the phase of the birth sine wave is adjusted according to the frequency of the birth sine wave.

Abstract: Provided are a method and apparatus for encoding an audio signal and a method and apparatus for decoding an audio signal. The method includes performing sinusoidal analysis on an audio signal in order to extract a sinusoidal signal of a current frame, determining continuation sinusoidal signal information indicating a number of continuation sinusoidal signals of next frames, which continue from the sinusoidal signal of the current frame, by performing sinusoidal tracking on the extracted sinusoidal signal of the current frame, and encoding the determined continuation sinusoidal signal information by using different Huffman tables according to index information of the current frame, thereby allowing efficient encoding with a low bitrate.

Abstract: Provided are an encoding method and apparatus for efficiently encoding a sinusoidal signal whose magnitude is less than a masking value according to a psychoacoustic model, a decoding method and apparatus for decoding an encoded sinusoidal signal, and a computer-readable recording medium having recorded thereon a program for executing the encoding method/the decoding method. By using a particular code indicating that the magnitude of a first sinusoidal signal is less than a masking value according to a psychoacoustic model to encode the first sinusoidal signal, difference coding for a third sinusoidal signal of a next frame, which is connected to the first sinusoidal signal, is performed using a sinusoidal signal or sinusoidal signals selected according to a method to use the particular code, and a decoding apparatus obtains a sum with a transmitted difference using the selected sinusoidal signal(s).

Abstract: An audio encoding method and apparatus, and an audio decoding method and apparatus, for processing a death sinusoid and a general continuation sinusoid. Using the unique characteristic of a death sinusoid, in that the death sinusoid has a tendency such that an amplitude component of the death sinusoid is less than that of a previous sinusoid, a method of adding an encoding syntax by distinguishing a general continuation sinusoid from a death sinusoid is provided. That is, when difference coding of the amplitude component of a death sinusoid is performed, the number of bits used when a negative number is coded is less than the number of bits used when a positive number is coded, in a Huffman table. By using this method, a bit rate in an entire coding decreases.

Abstract: An audio signal encoding method and apparatus for efficiently encoding an audio signal in an interval having many birth sinusoids and enabling tracking of sinusoidal signals in the next interval, and a computer readable recording medium having embodied thereon a computer program for executing the audio signal encoding method are provided. According to the method and apparatus, by applying transform coding instead of parametric coding to a frame having many birth sinusoids, the sinusoids are encoded, thereby reducing the number of bits required for the encoding and enabling efficient coding. Also, when transform coding is applied to a frame of a predetermined interval, an inverse transform of the transform coding is applied to the encoded data in order to decode the data, and then sinusoids are extracted from the decoded data, thereby enabling tracking of sinusoids of the next frame.

Abstract: Provided are a method and apparatus for sinusoidal audio coding, which employs a tracking method for further effective coding of sinusoids extracted in the process of a sinusoidal analysis of parametric coding. The sinusoidal audio coding method includes: extracting sinusoids of a current frame by performing a sinusoidal analysis on an input audio signal; with respect to each of the extracted sinusoids, setting a mode selected from a birth mode in which a sinusoid is newly generated irrespective of sinusoids of a previous frame, a continuation mode in which the sinusoid is only one sinusoid continued from one of the sinusoids of the previous frame, and a branch mode in which the sinusoid is one of a plurality of sinusoids continued from one of the sinusoids of the previous frame; and coding the extracted sinusoids according to the selected mode. Accordingly, a plurality of sinusoids that can be continued from one previous track component are set to the continuation mode or the branch mode.