Systems, methods and computer software are disclosed for handling variable payload lengths which are based on different Adaptive Multi-Rate (AMR) audio codecs. In one embodiment, the method includes sending a message during flow establishment giving an Active Codec Set (ACS) and a codec type by sending a message; preparing a map where each bit of the map indicates a Frame Type (FT) during establishment of the flow; extracting the FT from the received packet in the received Adaptive Multi-Rate (AMR) header; using the extracted FT, checking if the rate is supported and if supported, obtaining a payload length for that rate from a table; and once an AMR payload length is known performing further processing.

A method for spatial audio signal encoding comprising: obtaining, for a first frame, a plurality of audio direction parameters, wherein each parameter comprises an elevation value and an azimuth value and wherein each parameter has an ordered position; determining whether, for a preceding frame, any of the plurality of audio direction parameters was differentially encoded based on a difference between the preceding frame parameter elevation value and a further preceding frame parameter elevation value and the preceding frame parameter azimuth value and a further preceding frame parameter azimuth value; generating, for any audio direction parameter which was not differentially encoded in the considered preceding frame, a differential parameter value based on a difference between the frame parameter elevation value and a preceding frame parameter elevation value and a difference between the frame parameter azimuth value and a preceding frame parameter azimuth value; generating for each of the plurality of audio direction parameters a difference parameter value based on a difference between the audio direction parameter and a rotated derived audio direction parameter; quantizing the difference between the audio direction parameter and a rotated derived audio direction parameter and the differential parameter value; and selecting for each of the plurality of audio direction parameters, either of the quantized difference or differential parameter value.

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.sup.SEG, 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, an encoder and a decoder are configured for transition between frames with different internal sampling rates. Linear predictive (LP) filter parameters are converted from a sampling rate S1 to a sampling rate S2. A power spectrum of a LP synthesis filter is computed, at the sampling rate S1, using the LP filter parameters. The power spectrum of the LP synthesis filter is modified to convert it from the sampling rate S1 to the sampling rate S2. The modified power spectrum of the LP synthesis filter is inverse transformed to determine autocorrelations of the LP synthesis filter at the sampling rate S2. The autocorrelations are used to compute the LP filter parameters at the sampling rate S2.

An apparatus comprising means configured to: obtain at least one direction parameter value for a time-frequency part of at least one audio signal (301); obtain at least one energy ratio for the time-frequency part (301), wherein each energy ratio is associated with a respective direction parameter value; generate respective at least one modified energy ratio from the at least one energy ratio for the time-frequency part (304); determine a quantization spatial resolution for encoding the at least one obtained direction parameter value based on the at least one modified energy ratio (305); and encode the obtained direction parameter values based on the quantization spatial resolution (306).

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.sup.SEG, 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.

A quantization device includes: a trellis-structured vector quantizer which quantizes a first error vector between an N-dimensional (here, “N” is two or more) subvector and a first predictive vector; and an inter-frame predictor which generates a first predictive vector from the quantized N-dimensional subvector, wherein the inter-frame predictor uses a predictive coefficient comprising an N×N matrix and performs an inter-frame prediction using the quantized N-dimensional subvector of a previous stage.

Methods, an encoder and a decoder are configured for transition between frames with different internal sampling rates. Linear predictive (LP) filter parameters are converted from a sampling rate S1 to a sampling rate S2. A power spectrum of a LP synthesis filter is computed, at the sampling rate S1, using the LP filter parameters. The power spectrum of the LP synthesis filter is modified to convert it from the sampling rate S1 to the sampling rate S2. The modified power spectrum of the LP synthesis filter is inverse transformed to determine autocorrelations of the LP synthesis filter at the sampling rate S2. The autocorrelations are used to compute the LP filter parameters at the sampling rate S2.

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.sup.SEG, 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.

A quantization device includes: a trellis-structured vector quantizer which quantizes a first error vector between an N-dimensional (here, “N” is two or more) subvector and a first predictive vector; and an inter-frame predictor which generates a first predictive vector from the quantized N-dimensional subvector, wherein the inter-frame predictor uses a predictive coefficient comprising an N×N matrix and performs an inter-frame prediction using the quantized N-dimensional subvector of a previous stage.