AUDIO ENCODER AND DECODER
FIG1 is a generalized block diagram of an audio encoding system in accordance with an example embodiment
FIG1 shows a generalized block diagram of an audio encoding system 100 for encoding audio objects 104. The audio encoding system comprises a downmixing component 106 which creates a downmix signal 110 from the audio objects 104. The downmix signal 110 may for example be a 5.1 or 7.1 surround signal which is backwards compatible with established sound decoding systems such as Dolby Digital Plus or MPEG standards such as AAC, USAC or MP3. In further embodiments, the downmix signal is not backwards compatible. The upmix matrix decoder 502 further comprises a decoding component 608 which is 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. This representation is thus the decoded version of the parameter encoded by for example the audio encoding system 100 shown in FIG1. In other words, this representation is equal to the quantized parameter encoded by the audio encoding system 100 shown in FIG1. The decoding component 608 is configured to represent the first element of the vector of parameters by a parameter value corresponding to the index value associated with the first entropy coded symbol. This representation is thus the decoded version of the parameter encoded by for example the audio encoding system 100 shown in FIG1.
block diagram
202
receiving component
1
elements may be one e.g. - value EEE
100
audio encoding system
208
encoding component
206
associating component
204
indexing component
2
e.g. EEE
104
audio objects
112
upmix parameter analysis component
102
encoder
108
filter bank
106
downmixing component
110
downmix signal
114
upmix parameters
['1. A method 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 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, wherein the selected subset of elements comprises the same number of elements for each row of 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, 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, wherein each vector of the one or more vectors of parameters has a first element (1002) and at least one second element (902), and wherein the one or more vectors of parameters are encoded by: 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; and 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; and applying (S806) modulo N to the shifted index value; and 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.', '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.']