Telefonaktiebolaget Lm Ericsson (publ)

Jonas Svedberg

Volodya Grancharov

Stefan Bruhn

Tomas Jansson Toftgård

Martin Sehlstedt

Anders Tomas Uvliden

Ingemar Johansson

Tomas Frankkila

Magnus Westerlund

Tomas Jönsson

Sebastian Näslund

Krister Svanbro

Jim Sundqvist

Erik Ekudden

Tomas Lundberg

Anders Nohlgren

Tor Björn Minde

Nicklas Sandgren

Arne Steinarson

Björn Svensson

A frame error concealment method based on frames including transform coefficient vectors including the following steps: It tracks sign changes between corresponding transform coefficients of predetermined sub-vectors of consecutive good stationary frames. It accumulates the number of sign changes in corresponding sub-vectors of a predetermined number of consecutive good stationary frames. It reconstructs an erroneous frame with the latest good stationary frame, but with reversed signs of transform coefficients in sub-vectors having an accumulated number of sign changes that exceeds a predetermined threshold.

Frame error concealment

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

A method, decoder, and program code for controlling a concealment method for a lost audio frame is provided. A first audio frame and a second audio frame of the received audio signal are decoded to obtain modified discrete cosine transform (MDCT) coefficients. Values of a first spectral shape based upon the MDCT coefficients decoded from the first audio frame decoded and values of a second spectral shape based upon MDCT coefficients decoded from the second audio frame decoded are determined, the spectral shapes each comprising a number of sub-bands. The values of the spectral shapes and frame energies of the first audio frame and second audio frame are transformed into representations of FFT based spectral analyses. A transient condition is detected based on the representations of the FFTs. Responsive to detecting the transient condition, the concealment method is modified by selectively adjusting a spectrum magnitude of a substitution frame spectrum.

Spectral shape estimation from MDCT coefficients

A method performed by an encoder. The method comprises determining envelope representation residual coefficients as first compressed envelope representation coefficients subtracted from the input envelope representation coefficients. The method comprises transforming the envelope representation residual coefficients into a warped domain so as to obtain transformed envelope representation residual coefficients. The method comprises applying, at least one of a plurality of gain-shape coding schemes on the transformed envelope representation residual coefficients in order to achieve gain-shape coded envelope representation residual coefficients, where the plurality of gain-shape coding schemes have mutually different trade-offs in one or more of gain resolution and shape resolution for one or more of the transformed envelope representation residual coefficients. The method comprises transmitting, over a communication channel to a decoder, a representation of the first compressed envelope representation coefficients, the gain-shape coded envelope representation residual coefficients, and information on the at least one applied gain-shape coding scheme.

Methods, encoder and decoder for handling envelope representation coefficients

An encoder and a method therein for Pyramid Vector Quantizer, PVQ, shape search, the PVQ taking a target vector x as input and deriving a vector y by iteratively adding unit pulses in an inner dimension search loop. The method comprises, before entering a next inner dimension search loop for unit pulse addition, determining, based on the maximum pulse amplitude, maxamp, of a current vector y, whether more than a current bit word length is needed to represent enloop, in a lossless manner in the upcoming inner dimension loop. The variable enloopis related to an accumulated energy of the vector y. The performing of this method enables the encoder to keep the complexity of the search at a reasonable level.

Pyramid vector quantizer shape search

In accordance with an example embodiment of the present invention, disclosed is a method and an apparatus thereof for controlling a concealment method for a lost audio frame of a received audio signal. A method for a decoder of concealing a lost audio frame comprises detecting in a property of the previously received and reconstructed audio signal, or in a statistical property of observed frame losses, a condition for which the substitution of a lost frame provides relatively reduced quality. In case such a condition is detected, the concealment method is modified by selectively adjusting a phase or a spectrum magnitude of a substitution frame spectrum.

Method and apparatus for controlling audio frame loss concealment

A method and apparatus for handling input Line Spectral Frequency, LSF, coefficients. The method comprises determining LSF residual coefficients as first compressed LSF coefficients subtracted from the input LSF coefficients, and transforming the LSF residual coefficients into a warped domain. One of a plurality of gain-shape coding schemes is applied on the transformed LSF residual coefficients in order to achieve gain-shape coded LSF residual coefficients, where the plurality of gain-shape coding schemes have mutually different trade-offs in one or more of gain resolution and shape resolution for one or more of the transformed LSF residual coefficients. A representation of the first compressed LSF coefficients, the gain-shape coded LSF residual coefficients, and information on the applied gain-shape coding scheme are transmitted over a communication channel to a decoder.

Methods, encoder and decoder for handling line spectral frequency coefficients

A method for pyramid vector quantization deindexing of coefficients derived from an audio or video signal includes receiving a first sign and an input index as codewords from an ingoing bit stream. The first sign and the input index represent the coefficients, and the first sign is a sign of a first or last non-zero coefficient in an output vector to be created. The method includes deindexing the input index into the output vector with a pyramid vector quantization de-enumeration scheme, assigning a sign of the first or last non-zero coefficient in the output vector according to the received first sign, and outputting the output vector.

Growing community of inventors

Luleå, Sweden

Jonas Svedberg