Audio Encoder and Decoder
AssigneeDolby International AB
InventorsLeif Jonas SAMUELSSON, Heiko PURNHAGEN
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Abstract
The present disclosure provides methods, devices and computer program products for encoding and decoding of a vector of parameters in an audio coding system. The disclosure further relates to a method and apparatus for reconstructing an audio object in an audio decoding system. According to the disclosure, a modulo differential approach for coding and encoding a vector of a non-periodic quantity may improve the coding efficiency and provide encoders and decoders with less memory requirements. Moreover, an efficient method for encoding and decoding a sparse matrix is provided.
Claims34
A method for encoding a vector of parameters in an audio encoding system, each parameter corresponding to a non-periodic quantity, the vector having a first element and at least one second element, the method comprising:
- representing each parameter in the vector by an index value which may take N values;
- associating each of the at least one second element with a symbol, the symbol being calculated by:
- calculating a difference between the index value of the second element and the index value of its preceding element in the vector;
- applying modulo N to the difference;
- encoding each of the at least one second element by entropy coding of the symbol associated with the at least one second element based on a probability table comprising probabilities of the symbols.
An encoder for encoding a vector of parameters in an audio encoding system, each parameter corresponding to non-periodic quantity, the vector having a first element and at least one second element, the encoder comprising:
- a receiving component adapted to receive the vector;
- an indexing component adapted to represent each parameter in the vector by an index value which may take N values;
- an associating component adapted to associate each of the at least one second element with a symbol, the symbol being calculated by:
- calculating a difference between the index value of the second element and the index value of its preceding element in the vector;
- applying modulo N to the difference;
- an encoding component for encoding each of the at least one second element by entropy coding of the symbol associated with the at least one second element based on a probability table comprising probabilities of the symbols.
A method for decoding a vector of entropy coded symbols in an audio decoding system into a vector of parameters relating to a non-periodic quantity, the vector of entropy coded symbols comprising a first entropy coded symbol and at least one second entropy coded symbol and the vector of parameters comprising a first element and at least one second element, the method comprising:
- representing each entropy coded symbol in the vector of entropy coded symbols by a symbol which may take N integer values by using a probability table;
- associating the first entropy coded symbol with an index value;
- associating each of the at least one second entropy coded symbol with an index value, the index value of the at least one second entropy coded symbol being calculated by:
- calculating the sum of the index value associated with the of entropy coded symbol preceding the second entropy coded symbol in the vector of entropy coded symbols and the symbol representing the second entropy coded symbol;
- applying modulo N to the sum;
- representing the at least one second element of the vector of parameters by a parameter value corresponding to the index value associated with the at least one second entropy coded symbol.
A decoder for decoding a vector of entropy coded symbols in an audio decoding system into a vector of parameters relating to a non-periodic quantity, the vector of entropy coded symbols comprising a first entropy coded symbol and at least one second entropy coded symbol and the vector of parameters comprising a first element and at least a second element, the decoder comprising:
- a receiving component configured to receive the vector of entropy coded symbols;
- a indexing component configured to represent each entropy coded symbol in the vector of entropy coded symbols by a symbol which may take N integer values by using a probability table;
- an associating component configured to associate the first entropy coded symbol with an index value;
- the associating component further configured to associate each of the at least one second entropy coded symbol with a index value, the index value of the at least one second entropy coded symbol being calculated by:
- calculating the sum of the index value associated with the entropy coded symbol preceding the second entropy coded symbol in the vector of entropy coded symbols and the symbol representing the second entropy coded symbol;
- applying modulo N to the sum;
- a decoding component configured to represent the at least one second element of the vector of parameters by a parameter value corresponding to the index value associated with the at least one second entropy coded symbol.
A method for encoding an upmix matrix in an audio encoding system, each row of the upmix matrix comprising M elements allowing reconstruction of a time/frequency tile of an audio object from a downmix signal comprising M channels, the method comprising:
- for each row in the upmix matrix:
- selecting a subset of elements from the M elements of the row in the upmix matrix;
- representing each element in the selected subset of elements by a value and a position in the upmix matrix;
- encoding the value and the position in the upmix matrix of each element in the selected subset of elements.
An encoder for encoding an upmix matrix in an audio encoding system, each row of the upmix matrix comprising M elements allowing reconstruction of a time/frequency tile of an audio object from a downmix signal comprising M channels, the encoder comprising:
- a receiving component adapted to receive each row in the upmix matrix;
- a selection component adapted to select a subset of elements from the M elements of the row in the upmix matrix;
- an encoding component adapted to represent each element in the selected subset of elements by a value and a position in the upmix matrix, the encoding component further adapted to encode the value and the position in the upmix matrix of each element in the selected subset of elements.
A method for reconstructing a time/frequency tile of an audio object in an audio decoding system, comprising:
- receiving a downmix signal comprising M channels;
- receiving at least one encoded element representing a subset of M elements of a row in an upmix matrix, each encoded element comprising a value and a position in the row in the upmix matrix, the position indicating one of the M channels of the downmix signal to which the encoded element corresponds;
- and
- reconstructing the time/frequency tile of the audio object from the downmix signal by forming a linear combination of the downmix channels that correspond to the at least one encoded element, wherein in said linear combination each downmix channel is multiplied by the value of its corresponding encoded element.
A decoder for reconstructing a time/frequency tile of an audio object, comprising:
- a receiving component configured to receive a downmix signal comprising M channels and at least one encoded element representing a subset of M elements of a row in an upmix matrix, each encoded element comprising a value and a position in the row in the upmix matrix, the position indicating one of the M channels of the downmix signal to which the encoded element corresponds;
- and
- a reconstructing component configured to reconstruct the time/frequency tile of the audio object from the downmix signal by forming a linear combination of the downmix channels that correspond to the at least one encoded element, wherein in said linear combination each downmix channel is multiplied by the value of its corresponding encoded element.
Dependencies are inferred from the claim text.