Abstract: The invention relates to an encoder and a decoder and methods therein for supporting split gain shape vector encoding and decoding. The method performed by an encoder, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, BMAX, allowed for encoding a vector segment. The method comprises, determining an initial number, Np—init, of segments for a target vector x; and further determining an average number of bits per segment, BAVG, based on a vector bit budget and Np—init. The method further comprises determining a final number of segments to be used, for the vector x, in the gain shape vector encoding, based on energies of the Np—init segments and a difference between BMAX and BAVG. The performing of the method enables an efficient allocation of the bits of the bit budget over the target vector.

Abstract: The embodiments of the present invention improves conventional attenuation schemes by replacing constant attenuation with an adaptive attenuation scheme that allows more aggressive attenuation, without introducing audible change of signal frequency characteristics.

Abstract: Audio decoder and method therein for supporting bandwidth extension (BWE) of a received signal. The method involves receiving a first signal representing the lower frequency spectrum of a segment of an original audio signal; receiving a second signal, being a BWE signal, representing a higher frequency spectrum of the segment of the original audio signal. The method further comprises determining a degree of voicing in the lower frequency spectrum of the audio signal, based on the received first signal; and selecting a spectral tilt adaptation filter, out of at least two spectral tilt adaptation filters having different spectral attenuation characteristics, based on the determined degree of voicing. The selected spectral tilt adaptation filter is then applied on the received second signal. Thus, a differentiation of spectral tilt in the higher frequency spectrum of a reconstructed audio signal, based on lower frequency spectrum characteristics of the original audio signal is enabled.

Abstract: The embodiments of the present invention improves conventional attenuation schemes by replacing constant attenuation with an adaptive attenuation scheme that allows more aggressive attenuation, without introducing audible change of signal frequency characteristics.

Abstract: An object of embodiments of the present invention is to provide an improved gain-shape VQ. This is achieved by determining a number of bits to be allocated to a gain adjustment- and shape-quantizer for a plurality of combinations of a current bit rate and a first signal property. The determined allocated number of bits to the gain adjustment- and shape quantizer should provide a better result for the given bitrate and signal property than using a single fixed allocation scheme. That can be achieved by deriving the bit allocation by using an average of optimal bit allocations for a training data set. Thus by pre-calculating a number of bits to the gain adjustment and the shape quantizers for a plurality of combinations of the bit rate and a first signal property and creating a table indicating the number of bits to be allocated to the gain adjustment- and the shape-quantizers for a plurality of combinations of the bit rate and a first signal property.

Abstract: In a quantization method for quantizing a received excitation signal in a communication system performing the steps of re-shuffling S301 the elements of the received excitation signal to provide a re-shuffled excitation signal; coding S302 the re-shuffled excitation signal with a variable bit-rate algorithm to provide a coded excitation signal; and reassigning S303 codewords of the coded excitation signal if a number of used bits exceeds a predetermined fixed bit rate requirement to provide a quantized excitation signal.

Abstract: The invention relates to an encoder and a decoder and methods therein for supporting split gain shape vector encoding and decoding. The method performed by an encoder, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, BMAX, allowed for encoding a vector segment. The method comprises, determining an initial number, Np—init, of segments for a target vector x; and further determining an average number of bits per segment, BAVG, based on a vector bit budget and Np—init. The method further comprises determining a final number of segments to be used, for the vector x, in the gain shape vector encoding, based on energies of the Np—init segments and a difference between BMAX and BAVG. The performing of the method enables an efficient allocation of the bits of the bit budget over the target vector.

Abstract: The invention relates to a codec and a signal classifier and methods therein for signal classification and selection of a coding mode based on audio signal characteristics. A method embodiment to be performed by a decoder comprises, for a frame m: determining a stability value D(m) based on a difference, in a transform domain, between a range of a spectral envelope of frame m and a corresponding range of a spectral envelope of an adjacent frame m-1. Each such range comprises a set of quantized spectral envelope values related to the energy in spectral bands of a segment of the audio signal. The method further comprises selecting a decoding mode, out of a plurality of decoding modes, based on the stability value D(m); and applying the selected decoding mode.

Abstract: An audio signal is coded, where a frequency spectrum of the audio signal is divided into first and second regions. Spectral peaks in the first region are encoded by a first coding method. For a segment of the audio signal, a relation between an energy of a band in the second region and an energy estimate of the first region is determined. A relation between the energy of the band in the second region and energy of neighboring bands in the second region is determined. A determination is made whether available bits are sufficient for encoding at least one non-peak segment of the first region and the band in the second region. Further, when the relations fulfill a respective criterion and the bits are sufficient, the band in the second region and the at least one segment of the first region are encoded using a second coding method.

Abstract: The embodiments of the present invention improves conventional attenuation schemes by replacing constant attenuation with an adaptive attenuation scheme that allows more aggressive attenuation, without introducing audible change of signal frequency characteristics.

Abstract: The invention relates to an encoder and a decoder and methods therein for supporting split gain shape vector encoding and decoding. The method performed by an encoder, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, BMAX, allowed for encoding a vector segment. The method comprises, determining an initial number, Np—init, of segments for a target vector x; and further determining an average number of bits per segment, BAVG, based on a vector bit budget and Np—init. The method further comprises determining a final number of segments to be used, for the vector x, in the gain shape vector encoding, based on energies of the Np—init segments and a difference between BMAX and BAVG. The performing of the method enables an efficient allocation of the bits of the bit budget over the target vector.

Abstract: The embodiments of the present invention improves conventional attenuation schemes by replacing constant attenuation with an adaptive attenuation scheme that allows more aggressive attenuation, without introducing audible change of signal frequency characteristics.

Abstract: The invention relates to the technical field of audio encoding and/or decoding technologies, and thus concerns an overall encoding procedure and associated decoding procedure. The encoding procedure involves at least two signal encoding processes (S1-S3) operating on signal representations of a set of audio input channels, as well as residual encoding (S7-S8). It also involves a dedicated process (S4-S6) to estimate and encode energies of the audio input channels. Each encoding process is associated with a corresponding decoding process. In the overall decoding procedure the decoded signals from each encoding process are preferably combined such that the output channels are close to the input channels in terms of energy and/or quality. Normally, the combination step also adapts to the possible loss of one or more signal representation in part or in whole, such that the energy and quality is optimized with the signals at hand in the decoder. In this way, the overall quality of the output channels is improved.

Abstract: The invention relates to a codec and a discriminator and methods therein for audio signal discrimination and coding. Embodiments of a method performed by an encoder comprises, for a segment of the audio signal: identifying a set of spectral peaks; determining a mean distance S between peaks in the set; and determining a ratio, PNR, between a peak envelope and a noise floor envelope. The method further comprises selecting a coding mode, out of a plurality of coding modes, based at least on the mean distance S and the ratio PNR; and applying the selected coding mode for coding of the segment of the audio signal.

Abstract: A method for encoding of an audio signal comprises performing (214) of a transform of the audio signal. An energy offset is selected (216) for each of the first subbands. An energy measure of a first reference band within a low band of an encoding of a synthesis signal is obtained (212). The first high band is encoded (220) by providing quantization indices representing a respective scalar quantization of a spectrum envelope in the first subbands of the first high band relative to the energy measure of the first reference band by use of the selected energy offset. An encoder apparatus comprises means for carrying out the steps of the method. Corresponding decoder methods and apparatuses are also described.

Abstract: The invention relates to an encoder and a decoder and methods therein for supporting split gain shape vector encoding and decoding. The method performed by an encoder, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, BMAX, allowed for encoding a vector segment. The method comprises, determining an initial number, Np—init of segments for a target vector x; and further determining an average number of bits per segment, BAVG, based on a vector bit budget and Np—init. The method further comprises determining a final number of segments to be used, for the vector x, in the gain shape vector encoding, based on energies of the Np—init segments and a difference between BMAX and BAVG. The performing of the method enables an efficient allocation of the bits of the bit budget over the target vector.

Abstract: An audio decoder configured to generate a high band extension of an audio signal from an envelope and an excitation. The audio decoder includes a control arrangement configured to jointly control envelope shape and excitation noisiness with a common control parameter (f).

Abstract: In a quantization method for quantizing a received excitation signal in a communication system performing the steps of re-shuffling S301 the elements of the received excitation signal to provide a re-shuffled excitation signal; coding S302 the re-shuffled excitation signal with a variable bit-rate algorithm to provide a coded excitation signal; and reassigning S303 codewords of the coded excitation signal if a number of used bits exceeds a predetermined fixed bit rate requirement to provide a quantized excitation signal.

Abstract: The present invention relates to a frequency domain based method of encoding and decoding an audio signal, wherein an adaptive spectral code book is updated with synthesized frequency domain representations of a time domain signal segment. A frequency analysis is performed of a received time domain signal segment in order to obtain a frequency domain representation, and the adaptive spectral code book is searched for a first approximation of the frequency domain representation. A fixed spectral code book is searched for an approximation of the residual frequency representation. A synthesized frequency domain representation may be generated from the two approximations.

Abstract: Audio decoder and method therein for supporting bandwidth extension (BWE) of a received signal. The method involves receiving a first signal representing the lower frequency spectrum of a segment of an original audio signal; receiving a second signal, being a BWE signal, representing a higher frequency spectrum of the segment of the original audio signal. The method further comprises determining a degree of voicing in the lower frequency spectrum of the audio signal, based on the received first signal; and selecting a spectral tilt adaptation filter, out of at least two spectral tilt adaptation filters having different spectral attenuation characteristics, based on the determined degree of voicing. The selected spectral tilt adaptation filter is then applied on the received second signal. Thus, a differentiation of spectral tilt in the higher frequency spectrum of a reconstructed audio signal, based on lower frequency spectrum characteristics of the original audio signal is enabled.