Abstract: An encoder (100) for encoding a multi-channel audio signal comprises a prediction processor (101) which generates two residual signals for two signal components of the multi-channel signal by linear prediction which is associated with psycho-acoustic prediction filters. A rotation processor (105) rotates the combined signal of the two residual signals to generate a main signal and a side signal. Preferably, the energy of the main signal is maximized and the energy of the side signal is minimized. An encoding processor (109) encodes the main and preferably the side signal and an output processor (111) generates an output signal comprising the encoded main data and preferably the side data, prediction parameters and rotation parameters.

Abstract: This document gives a technical description of a multi-channel parametric audio coding system. The goal of this system is to describe an m-channel signal by an n-channel signal, with n<m, and parameters describing a spatial image in order to reconstruct the m-channel signal.

Abstract: The method creates an audio stream comprising tracks of sinusoidal components linked across a plurality of sequential time segments. Segments in each track are weighted with a normal window (WI, W2, W3), and consecutive segments have a normal period of overlap (0) of their trailing edges and leading edges. Segments in which a transient 5 component is determined are weighted with a first modified window (WIm) having a modified trailing edge, and the following segment in the track is weighted with a second modified window (W2m) having a modified leading edge, so that the modified trailing edge and the modified leading edge have a modified period of overlap (0m) that comprises the transient component and that is shorter than the normal period of overlap (0), and wherein the audio stream includes sinusoidal codes representing the frequency and the transient. According to the invention, the modified period of overlap (0m) depends on the frequency value (f).

Abstract: The present invention relates to a method of encoding and decoding an audio signal. The invention further relates to an arrangement for encoding and decoding an audio signal. The invention further relates to a computer-readable medium comprising a data record indicative of an audio signal and a device for communicating an audio signal having been encoded according to the present invention. By the method of encoding, a double description of the signal is obtained, where the encoding comprises two encoding steps, a first standard encoding and an additional second encoding. The second encoding is able to give a coarse description of the signal, such that a stochastic realization can be made and appropriate parts can be added to the decoded signal from the first decoding. The required description of the second encoder in order to make the realization of a stochastic signal possible requires a relatively low bit rate, while other double/multiple descriptions require a much higher bit rate.

Abstract: A method of encoding (1) an audio signal (x(t)) by representing (12) at least part of said audio signal by a plurality of sinusoids. The method comprising the steps of performing an analysis on a first segment of said audio signal, selecting candidate sinusoids based on said analysis, defining for at least one of the candidate sinusoids a local frequency band around said candidate sinusoid's frequency, combining amplitudes of frequency components within said local frequency band from which at least one of the candidate sinusoids within said local frequency band is excluded, and selecting said candidate sinusoid as a selected sinusoid in dependence on the combination of amplitudes. The selection of sinusoids according to the invention will result in a smaller number of sinusoids to be encoded for a given audio quality, which is advantageous in terms of hit-rate for a given audio quality.

Abstract: In a sinusoidal audio encoder a number of sinusoids are estimated per audio segment. A sinusoid is represented y frequency, amplitude and phase. Normally, phase is quantised independent of frequency The invention uses a frequency dependent quantisation of phase, and in particular the low frequencies are quantised using smaller quantisation intervals than at higher frequencies. Thus, the unwrapped phases of the lower frequencies are quantised more accurately, possibly with a smaller quantisation range, than the phases of the higher frequencies.

Abstract: An audio coder is arranged to process a respective set of sampled signal values for each of a plurality of sequential segments of an audio signal (x). The coder comprises an analyser (TSA) arranged to analyse the sampled signal values to provide one or more sinusoidal codes (Cs) corresponding to respective sinusoidal components of the audio signal. A subtractor subtracts a signal corresponding to the sinusoidal components from the audio signal to provide a first residual signal (r1). A modeller (SEG) models the frequency spectrum of the first residual signal (r1) by determining first filter parameters (Ps) of a filter which has a frequency response approximating a frequency spectrum of the first residual signal. Another subtractor subtracts a signal corresponding to the first filter parameters from the first residual signal to provide a second residual signal (r2).

Abstract: Coding of an audio signal (x) represented by a respective set of sampled signal values (x(t)) for each of a plurality of sequential time segments is disclosed. The sampled signal values are analyzed to determine one or more sinusoidal components for each of the plurality of sequential segments. The sinusoidal components are linked across a plurality of sequential segments to provide sinusoidal tracks, where each track comprises a number of frames. An encoded signal (AS) is generated, including sinusoidal codes (Cs) comprising a representation level (r) for each frame or including sinusoidal codes (Cs) where some of these codes comprise a phase (?), a frequency (?) and a quantization table (Q) for a given frame when the given frame is designated as a random-access frame. The invention allows random access in a track while avoiding long adaptation of the quantization accuracy in a quantizer and/or the need for a large bit stream while still maintaining improved audio quality.

Abstract: A method of encoding (1) an audio signal (x(t) is disclosed. The position of a transient signal component of the audio signal is estimated (110). A first portion (ti) of the transient signal component is modeled (111) with a first plurality of sinusoidal components. A difference (d) between the first portion (ti) of the transient signal component and the transient signal component is estimated. The difference is modeled with a measure (E) of the energy of the difference; and the measure (E) is included in an audio stream (AS).

Abstract: A method of encoding (1) an audio signal (x(t)) by representing (12) at least part of the audio signal by a plurality of sinusoids, the method comprising the steps of performing an analysis on a first segment of said audio signal, selecting candidate sinusoids based on said analysis, determining for at least one of the candidate sinusoids a phase consistency defined by an extent to which a phase of said candidate sinusoid at a certain moment in time can be predicted from a phase of said candidate sinusoid determined at another moment in time, and selecting said candidate sinusoid as a selected sinusoid when its phase consistency is above a predetermined threshold. The selection of sinusoids according to the invention will result in a smaller number of sinusoids to be encoded for a given audio quality, which is advantageous in terms of bit-rate for a given audio quality.

Abstract: The present invention relates to a method of encoding a main and a side signal that are generated by the first step of parametric stereo encoding. when encoding according to the present invention, firstly, the relation between the power spectral energies of the main and the side signal is kept intact per psycho acoustical band. Secondly, the side signal has to be uncorrelated with the main signal in psycho acoustical sense. the method of encoding the main and the side signal, according to the present invention, is twofold. Firstly, a filter is estimated which is able to re-instate the desired spectral amplitude relation and the temporal envelope.

Abstract: Modeling a target spectrum (S) is provided by determining (21) filter parameters (pi,qi) of a filter which has a frequency response approximating the target spectrum (S), wherein the target spectrum is split in at least a first part and a second part, a first modeling operation is used on the first part of the target spectrum to obtain auto-regressive parameters, a second modeling operation is used on the second part of the target spectrum to obtain moving-average parameters, and the auto-regressive parameters and the moving-average parameters are combined to obtain the filter parameters. The invention is preferably applied in audio coding, wherein a spectrum of a noise component (S) in the signal (A) is modeled.

Abstract: Coding of an audio signal represented by a respective set of sampled signal values for each of a plurality of sequential segments is disclosed. The sampled signal values are analysed (40) to determine one or more sinusoidal components for each of the plurality of sequential segments. The sinusoidal components are linked (42) across a plurality of sequential segments to provide sinusoidal tracks. For each sinusoidal track, a phase comprising a generally monotonically changing value is determined and an encoded audio stream including sinusoidal codes (r) representing said phase is generated (46).

Abstract: Coding of an audio signal (x) represented by a respective set of sampled signal values for each of a plurality of sequential segments is disclosed. The sampled signal values are analyzed (130) to generate one or more sinusoidal components (fk,fk-1) for each of the plurality of sequential segments. Sinusoidal codes (CS) comprising tracks of linked sinusoidal components (fk,fk-1) are generated (13) and phase update information (?k, ?k) indicative of the phase value of selected sinusoidal components in a track is determined. An encoded audio stream (AS) including said sinusoidal codes (CS) and said phase update information (?k, ?k) is then generated (15).

Abstract: Coding (1) an audio signal (x) comprises providing a respective set of sampled signal values for each of a plurality of sequential segments. The sampled signal values are analysed (130) to generate one or more sinusoidal components for each of the plurality of sequential segments. The sinusoidal components are linked across a plurality of sequential segments. Sinusoidal codes (CS) comprise tracks of linked sinusoidal components for each of the plurality of sequential segments. Each track comprises a frequency and amplitude for a sinusoidal component in a starting segment of a track whereas selected tracks include an indicator that no phase is included for said starting segment.

Abstract: A method of encoding (14) an audio signal (x(n)) is disclosed. The method comprises the step of modelling (16) the audio signal in accordance with a frequency sensitizing parameter (( ) to provide a set of infinite impulse response (IIR) filter type characteristics ((0 . . . k?1) of an order K and capable of being linearly combined with the sensitizing parameter (( ) to provide an estimate ( ) for the audio signal (x(n)), the IIR type filter model satisfying the requirements of a minimum phase filter. The set of characteristics ((0 . . . k?1) of order K are transformed as a function of the sensitizing parameter (( ) to provide a set of characteristics (c0 . . . k) of order K+1 compatible with finite impulse response (FIR) filter type characteristics satisfying the requirements of a minimum phase filter. The set of characteristics (c0 . . . k) of order K+1 are normalised to provide a set of characteristics (d1 . . . k) of order K.

Abstract: Coding (1) of an audio signal is provided including estimating (110) a position of a transient signal component in the audio signal, matching (111,112) a shape function on the transient signal component in case the transient signal component is gradually declining after an initial increase, which shape function has a substantially exponential initial behavior and a substantially logarithmic declining behavior; and including (15) the position and shape parameters describing the shape function in an audio stream (AS).

Abstract: The invention provides coding (11) of an at least two-channel audio signal (L,R) by determining common frequencies (fcom) in the at least two channels (L,R) of the audio signal, which common frequencies occur in at least two of the at least two channels of the audio signal, and by representing respective sinusoidal components in respective channels at a given common frequency by a representation of the given common frequency (fcom) and a representation of respective amplitudes (A,?A) of the respective sinusoidal components at the given common frequency.