AUDIO ENCODER AND DECODER
FIG5 is a generalized block diagram of an audio decoding system in accordance with an example embodiment
FIG5 is a generalized block diagram of an audio decoding system 500 for recreating encoded audio objects from a coded downmix signal 510 and a coded upmix matrix 512. The coded downmix signal 510 is received by a downmix receiving component 506 where the signal is decoded and, if not already in a suitable frequency domain, transformed to a suitable frequency domain. The decoded downmix signal 516 is then sent to the upmix component 508. In the upmix component 508, the encoded audio objects are recreated using the decoded downmix signal 516 and a decoded upmix matrix 504. More specifically, the upmix component 508 may perform a matrix operation in which the decoded upmix matrix 504 is multiplied by a vector comprising the decoded downmix signals 516. The decoding process of the upmix matrix is described below. The audio decoding system 500 further comprises a rendering component 514 which output an audio signal based on the reconstructed audio objects 518 depending on what type of playback unit that is connected to the audio decoding system 500.
block diagram
5
e.g.
502
decoder
606
component
9
max value is
506
downmix receiving component
508
upmix component
514
rendering component
500
audio decoding system
516
decoded downmix signal decoded downmix signals
504
decoded upmix matrix
602
receiving component
518
reconstructed audio objects
604
indexing component
510
coded downmix signal
23
filed
512
coded upmix matrix
608
decoding component
['4. An encoder (100) for encoding an upmix matrix in an audio encoding system (100), 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, wherein the selected subset of elements comprises the same number of elements for each row of 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 wherein, for each row in the upmix matrix and for a plurality of frequency bands or a plurality of time frames, the values of the elements and/or the positions of the elements of the selected subsets of elements form one or more vectors (114, 902, 1002) of parameters, each parameter in the vector of parameters corresponding to one of the plurality of  frequency bands or the plurality of time frames, the vector of parameters having a first element (1002) and at least one second element (902), wherein the encoding component is adapted to encode the one or more vectors of parameters by for each vector: representing (S702, S802) each parameter in the vector by an index value which takes one of N possible values; associating each of the at least one second element with a symbol, the symbol being calculated by: calculating (S704) a difference between the index value of the second element and the index value of its preceding element in the vector; applying (S706) modulo N to the difference; encoding (S708) 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 associating the first element in the vector with a symbol, the symbol being calculated by: shifting (S804) the index value representing the first element in the vector by subtracting an off-set value from the index value; applying (S806) modulo N to the shifted index value; encoding the first element by entropy coding of the symbol associated with the first element using the same probability table that is used to encode the at least one second element.', '5. A method for reconstructing a time/frequency tile of an audio object in an audio decoding system (1200), comprising: receiving a downmix signal (1210) comprising M channels; receiving at least one encoded element (1204) 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 (1208) 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 wherein, for a plurality of frequency bands or a plurality of time frames, the values and/or the positions of the at least one encoded element form one or more vectors (1214), wherein the positions of the at least one encoded element vary across a plurality of frequency bands and/or across a plurality of time frames, wherein each position is represented by an entropy coded symbol, wherein each symbol in each vector of entropy coded symbols corresponds to one of the plurality of frequency bands or the plurality of time frames, and wherein the one or more vectors of entropy coded symbols are decoded into one or more vectors of parameters, wherein each vector of entropy coded symbols comprises a first entropy coded symbol and at least one second entropy coded symbol and wherein each vector of parameters comprises a first element and at least one second element, wherein the decoding of each of the one or more vectors of entropy coded symbols comprises: 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; and applying modulo N to the sum; and 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, wherein the step of representing each entropy coded symbol in the vector of entropy coded symbols by a symbol is performed using the same probability table for all  entropy coded symbols in the vector of entropy coded symbols, wherein the index value associated with the first entropy coded symbol is calculated by: shifting the symbol representing the first entropy coded symbol in the vector of entropy coded symbols by adding an off-set value to the symbol; and applying modulo N to the shifted symbol, wherein the method further comprises the step of: representing the first element of the vector of parameters by a parameter value corresponding to the index value associated with the first entropy coded symbol.', '7. A decoder (1200) for reconstructing a time/frequency tile of an audio object, comprising: a receiving component (1206) configured to receive a downmix signal (1210) comprising M channels and at least one encoded element (1204) 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 (1208) 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, wherein, for a plurality of frequency bands or a plurality of time frames, the values and/or the positions of the at least one encoded element form one or more vectors (1214), wherein the positions of the at least one encoded element vary across a plurality of frequency bands and/or across a plurality of time frames, wherein each position is represented by an entropy coded symbol, wherein each  symbol in each vector of entropy coded symbols corresponds to one of the plurality of frequency bands or the plurality of time frames, and wherein the decoder further comprises a decoding component (1202) configured to decode the one or more vectors of entropy coded symbols into one or more vectors of parameters, wherein each vector of entropy coded symbols comprises a first entropy coded symbol and at least one second entropy coded symbol and wherein each vector of parameters comprises a first element and at least one second element, wherein the decoding component is configured to decode each of the one or more vectors of entropy coded symbols by: 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, wherein the step of representing each entropy coded symbol in the vector of entropy coded symbols by a symbol is performed using the same probability table for all entropy coded symbols in the vector of entropy coded symbols, wherein the index value associated with the first entropy coded symbol is calculated by: shifting the symbol representing the first entropy coded symbol in the vector of entropy coded symbols by adding an off-set value to the symbol; applying modulo N to the shifted symbol; and representing the first element of the vector of parameters by a parameter value corresponding to the index value associated with the first entropy coded symbol.']