An audio frame loss recovery method and apparatus are disclosed. In one implementation, data from some but not all audio frames is included in a redundant frame. The audio frames whose data is not included in the redundant frame may include multiple audio frames but may not include more than two consecutive audio frames. Because not all audio frames are used in the redundant frame, the amount of information needed to be transmitted in the redundant frame is reduced. A lost audio frame during transmission may be recovered from either the redundant frame when the redundant frame include data of the lost frame, or from at least one neighboring frame of the lost frame derived from either the redundant frame or the successfully transmitted audio frames when the redundant frame does not include data of the lost frame.

A method for hiding data within cover audio uses a set of sample codebook waveforms that are each assigned a unique representative digit value. A hidden data sequence representing the data is formed from the waveforms by concatenation of the waveforms assigned to the digit values of the data. The sequence is superimposed upon segments of the cover audio at a fractional amplitude. After transmission, the received signal is decompressed if necessary, the hidden data sequence is recovered from the cover audio, and the data is recovered from the hidden data sequence. This may be done by recovering the locations of the codebook waveforms and interpolating the time markers of the locations. The recovered data may be cleaned up by using estimated distances between successive cross-correlations to discard extraneous correlation peaks and sequence recurrence to probabilistically delete overlapping correlation peaks.

The present invention relates to a codec device and method for encoding/decoding voice and audio signals in a communication system, wherein: a fixed codebook excited signal is generated by using a pulse index for a voice signal; a first adaptive codebook excited signal is generated by using a pitch index for the voice signal; a fixed codebook signal is generated by multiplying the fixed codebook excited signal by a fixed codebook gain; a first adaptive codebook signal is generated by multiplying the first adaptive codebook excited signal by a first adaptive codebook gain; and a synthesized filter excited signal is generated by adding the fixed codebook signal and the first adaptive codebook signal.

A method for partitioning of input vectors for coding is presented. The method comprises obtaining (210) of an input vector. The input vector is segmented (220), 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 (230), in a recursive manner. The input vector segments and the representations of the relative energy differences are provided (250) for individual coding. Partitioning units and computer programs for partitioning of input vectors for coding, as well as positional encoders, are presented.

An audio encoder is disclosed for providing an encoded representation of an audio information encodes a sequence of audio frames. The audio encoder provides one or more immediate playout frames including a representation of a current audio frame, preceding the current audio frame. The audio encoder provides the representations of the current frame and of the one or more audio frames preceding the current audio frame, such that these representations are decodable using a same decoder configuration. The audio encoder provides the representations of the one or more audio frames preceding the current audio frame, which are included into the immediate playout frame, using a modified encoding functionality, which encodes an audio frame using a smaller number of bits than a normal encoding functionality, which is used for the encoding of the current audio frame.

Examples of the disclosure relate to apparatus, methods and computer programs for encoding spatial metadata. The example apparatus includes circuitry configured for obtaining spatial metadata associated with spatial audio content and obtaining a configuration parameter indicative of a source format of the spatial audio content. The circuitry is also configured to use the configuration parameter to select a method of compression of the spatial metadata associated with the spatial audio content.

An apparatus for encoding a speech signal by determining a codebook vector of a speech coding algorithm is provided. The apparatus includes a matrix determiner for determining an autocorrelation matrix R, and a codebook vector determiner for determining the codebook vector depending on the autocorrelation matrix R. The matrix determiner is configured to determine the autocorrelation matrix R by determining vector coefficients of a vector r, wherein the autocorrelation matrix R includes a plurality of rows and a plurality of columns, wherein the vector r indicates one of the columns or one of the rows of the autocorrelation matrix R, wherein R(i, j)=r(|i?j|), wherein R(i, j) indicates the coefficients of the autocorrelation matrix R, wherein i is a first index indicating one of a plurality of rows of the autocorrelation matrix R, and wherein j is a second index indicating one of the plurality of columns of the autocorrelation matrix R.

Methods, apparatus and articles of manufacture to identify sources of network streaming services are disclosed. An example apparatus includes a coding format identifier to identify, from a received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the second audio signal, and a source identifier to identify a source of the second audio signal based on the identified audio compression configuration.

An apparatus for encoding a speech signal by determining a codebook vector of a speech coding algorithm is provided. The apparatus includes a matrix determiner for determining an autocorrelation matrix R, and a codebook vector determiner for determining the codebook vector depending on the autocorrelation matrix R. The matrix determiner is configured to determine the autocorrelation matrix R by determining vector coefficients of a vector r, wherein the autocorrelation matrix R includes a plurality of rows and a plurality of columns, wherein the vector r indicates one of the columns or one of the rows of the autocorrelation matrix R, wherein R(i, j)=r(|i?j|), wherein R(i, j) indicates the coefficients of the autocorrelation matrix R, wherein i is a first index indicating one of a plurality of rows of the autocorrelation matrix R, and wherein j is a second index indicating one of the plurality of columns of the autocorrelation matrix R.

A method includes receiving, at an audio encoder, multiple streams of audio data, where N is the number of the received multi streams. The method includes determining a similarity value for each stream of the multiple streams and comparing the similarity value for each stream of the multiple streams with a threshold. The method also includes identifying, based on the comparison, L (L<N) number of streams to be encoded among the N number of the multiple streams. The method includes encoding the identified L number of streams to generate an encoded bitstream.