Telefonaktiebolaget Lm Ericsson (Publ)

Tomas Jansson Toftgård

Volodya Grancharov

Erik Norvell

Tommy Falk

Sebastian Näslund

Jonas Svedberg

Fredrik Klas Jansson

Manuel Briand

Erlendur Karlsson

Harald Pobloth

Werner De Bruijn

Mengqiu Zhang

Stefan Bruhn

Martin Sehlstedt

Rory Gamble

Charles Kinuthia

A method and device are disclosed for determining an inter-channel time difference of a multi-channel audio signal having at least two channels. A determination is made at a number of consecutive time instances, inter-channel correlation based on a cross-correlation function involving at least two different channels of the multi-channel audio signal. Each value of the inter-channel correlation is associated with a corresponding value of the inter-channel time difference. An adaptive inter-channel correlation threshold is adaptively determined based on adaptive smoothing of the inter-channel correlation in time. A current value of the inter-channel correlation is then evaluated in relation to the adaptive inter-channel correlation threshold to determine whether the corresponding current value of the inter-channel time difference is relevant. Based on the result of this evaluation, an updated value of the inter-channel time difference is determined.

Determining the inter-channel time difference of a multi-channel audio signal

A method of audio rendering. The method includes receiving an audio element, wherein the audio element comprises: i) an interior representation that is valid within a spatial region, the interior representation of the audio element being in a listener-centric format and ii) information indicating the spatial region. The method further includes determining that a listener is outside the spatial region. The method further includes deriving an exterior representation of the audio element and rendering the audio element using the exterior representation of the audio element. In another aspect, a method of providing a spatially-bounded audio element is provided. The method includes providing, to a rendering node, an audio element. The audio element includes: (i) an interior representation that is valid within a spatial region, the interior representation being in a listener-centric format; and (ii) information indicating the spatial region.

Spatially-bounded audio elements with interior and exterior representations

An audio signal processing method and apparatus for adaptively adjusting a decorrelator. The method comprises obtaining a control parameter and calculating mean and variation of the control parameter. Ratio of the variation and mean of the control parameter is calculated, and a decorrelation parameter is calculated based on the said ratio. The decorrelation parameter is then provided to a decorrelator.

Method and apparatus for adaptive control of decorrelation filters

In one aspect, there is a method for rendering a spatially-heterogeneous audio element. In some embodiments, the method includes obtaining two or more audio signals representing the spatially-heterogeneous audio element, wherein a combination of the audio signals provides a spatial image of the spatially-heterogeneous audio element. The method also includes obtaining metadata associated with the spatially-heterogeneous audio element, the metadata comprising spatial extent information indicating a spatial extent of the audio element. The method further includes rendering the audio element using: i) the spatial extent information and ii) location information indicating a position (e.g. virtual position) and/or an orientation of the user relative to the audio element.

Efficient spatially-heterogeneous audio elements for virtual reality

A method for generating a head-related (HR) filter for audio rendering is provided. The method comprises generating HR filter model data which indicates an HR filter model, and based on the generated HR filter model data, (i) sampling one or more basis functions and (ii) generating first basis function shape data and shape metadata. The method further comprises providing the generated first basis function shape data and the shape metadata for storing in one or more storage mediums.

Efficient head-related filter generation

A method for generating comfort noise is provided. The method includes providing a first set of background noise parameters Nfor at least one audio signal in a first spatial audio coding mode and a second set of background noise parameters Nfor the at least one audio signal in a second spatial audio coding mode. The first spatial audio coding mode is used for active segments; the second spatial audio coding mode is used for inactive segments. The method further includes adapting the first set of background noise parameters Nto the second spatial audio coding mode, thereby providing a first set of adapted background noise parameters {circumflex over (N)}. The method further includes generating comfort noise parameters by combining {circumflex over (N)}and Nover a transition period. The method further includes generating comfort noise based on the comfort noise parameters.

Comfort noise generation for multi-mode spatial audio coding

Transmitting node and receiving node for audio coding and methods therein. The nodes being operable to encode/decode speech and to apply a discontinuous transmission (DTX) scheme comprising transmission/reception of Silence Insertion Descriptor (SID) frames during speech inactivity. The method in the transmitting node comprising determining, from amongst a number N of hangover frames, a set Y of frames being representative of background noise, and further transmitting the N hangover frames, comprising at least said set Y of frames, to the receiving node. The method further comprises transmitting a first SID frame to the receiving node in association with the transmission of the N hangover frames, where the SID frame comprises information indicating the determined set Y of hangover frames to the receiving node. The method enables the receiving node to generate comfort noise based on the hangover frames most adequate for the purpose.

Methods and apparatuses for DTX hangover in audio coding

A method () for producing an estimated head-related (HR) filter, formula (I), that consists of a set of S HR filter sections formula (II) for s=1 to S. The method includes obtaining (s) an alpha matrix (e.g., an N×K matrix), wherein the alpha matrix consists of S sections, where each one of the sections of the alpha matrix corresponds to a different one of the S HR filter sections (e.g., the first section of the alpha matrix corresponds to formula (III), the second section of the alpha matrix corresponds to formula (IV), etc.), each section of the alpha matrix consists of N sub-vectors (N>1, e.g., N=8), and each sub-vector comprises a number of scalar values. The method further includes separately computing (s) each one of the S HR filter sections, wherein, for at least a certain one of the S HR filter sections, formula (II), the step of computing formula (II) comprises using not more than a predetermined number, q, of the sub-vectors within the section of the alpha matrix corresponding to formula (II) to compute formula (II), where qis less than N.

Head-related (HR) filters

A method for generating a comfort noise (CN) parameter is provided. The method includes receiving an audio input; detecting, with a Voice Activity Detector (VAD), a current inactive segment in the audio input; as a result of detecting, with the VAD, the current inactive segment in the audio input, calculating a CN parameter CN; and providing the CN parameter CNto a decoder. The CN parameter CNis calculated based at least in part on the current inactive segment and a previous inactive segment.

Adaptive comfort noise parameter determination

A method for partitioning of input vectors for coding is presented. The method comprises obtaining of an input vector. The input vector is segmented, in a non-recursive manner, into an integer number, N, of input vector segments. A representation of a respective relative energy difference between parts of the input vector on each side of each boundary between the input vector segments is determined, in a recursive manner. The input vector segments and the representations of the relative energy differences are provided for individual coding. Partitioning units and computer programs for partitioning of input vectors for coding, as well as positional encoders, are presented.

Methods and devices for vector segmentation for coding

An encoder for encoding frequency transform coefficients of a harmonic audio signal include the following elements: A peak locator configured to locate spectral peaks having magnitudes exceeding a predetermined frequency dependent threshold. A peak region encoder configured to encode peak regions including and surrounding the located peaks. A low-frequency set encoder configured to encode at least one low-frequency set of coefficients outside the peak regions and below a crossover frequency that depends on the number of bits used to encode the peak regions. A noise-floor gain encoder configured to encode a noise-floor gain of at least one high-frequency set of not yet encoded coefficients outside the peak regions.

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Uppsala, Sweden

Tomas Jansson Toftgård