US5890125A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for encoding and decoding multiple audio channels at low bit rates using adaptive selection of encoding method
Assignee: Dolby Laboratories Licensing Corp
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Filing: 1997-07-16
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Granted: 1999-03-30
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Expires: 2017-07-16
Abstract
Abstract A split-band coding system combines multiple channels of input signals into various forms of composite signals and generates spatial-characteristic signals representing soundfield spatial characteristics in a plurality of frequency subbands. The spatial-characteristics signals may be generated in either or both of two forms. In a first form, the signal represents measures of signal levels for subband signals from the input channels. In a second form, the signal represents one or more apparent directions for the soundfield. The type of the spatial-characteristics signal may be adapted dynamically in response to a variety of criteria including input signal characteristics. Temporal smoothing and spectral smoothing of the spatial-characteristics signals may be applied in an encoder. Temporal smoothing and spectral smoothing may be applied to gain factors derived from the spatial-characteristics signals in a decoder.
Inventors
- 👤 Mark Franklin Davis
- 👤 Matthew Conrad Fellers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:39
CPC Classifications
H; H04; H04S; H04S3/00; H04H; H04H20/00; H04H20/86; H04H20/88; G; G10; G10L; G10L19/00; G10L19/008; G10L19/02; G10L19/0204; G10L19/0208; H04B; H04B1/00; H04B1/66; H04B1/665; H04R; H04R5/00; H04R5/04; H04S2420/00; H04S2420/03
Claims Analysis
Total Claims: 81
Claim 1
Independent Claim
154 words
A method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 2
Independent Claim
154 words
A method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 3
Dependent Claim
46 words
A method according to claim 1 where, in response to said respective channel subband signals in a respective frequency subband, said spatial-characteristics signal is generated in said first form if said soundfield is deemed to have a number of apparent directions greater than a threshold number.
Claim 4
Dependent Claim
55 words
A method according to claim 2 wherein said threshold number is one and said soundfield is deemed to have one apparent direction when only one of said respective channel subband signals has significant spectral energy or when all of said respective channel subband signals having significant spectral energy also have correlated amplitudes and correlated phases.
Claim 5
Dependent Claim
31 words
A method according to claim 1 wherein said respective spatial-characteristics signal is generated in said second form such that it also represents a measure of soundfield dispersion about an intended direction.
Claim 6
Dependent Claim
44 words
A method according to claim 1 wherein said spatial-characteristics signal is generated in said first form such that rates of decrease in values of said information representing said signal levels are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 7
Independent Claim
119 words
A method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 8
Independent Claim
119 words
A method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 9
Dependent Claim
27 words
A method according to claim 1 or 6 wherein said composite signal is generated by combining two or more channel subband signals in a respective frequency subband.
Claim 10
Dependent Claim
46 words
A method according to claim 1 or 6 wherein said composite signal is a subband signal that is generated by applying a filter bank or a transform to a wideband signal, wherein said wideband signal is formed by combining two or more of said input signals.
Claim 11
Dependent Claim
37 words
A method according to claim 1 or 6 wherein said composite signal is generated by combining subband signals that are obtained by applying a filter bank or a transform to two or more of said input signals.
Claim 12
Dependent Claim
16 words
A method according to claim 1 or 6 wherein said composite signal is a parametric signal.
Claim 13
Dependent Claim
38 words
A method according to claim 6 wherein said spatial-characteristic signal represents one or more intended directions and rates of change in the spatial-characteristic signal are limited to control a rate at which said intended directions can change orientation.
Claim 14
Dependent Claim
44 words
A method according to claim 6 wherein said spatial-characteristic signal conveys information representing signal levels of said respective channel subband signals and said rates of change in the spatial-characteristic signal correspond to rates of decrease in values of said information representing the signal levels.
Claim 15
Dependent Claim
67 words
A method according to claim 1 or 6 wherein each of said respective channel subband signals is generated in response to a common time interval of said input signals, and wherein said method further comprises generating a delay signal indicating where in said common time interval an abrupt change in amplitude or direction occurs in said respective soundfield, and assembling said delay signal into said encoded signal.
Claim 16
Dependent Claim
58 words
A method according to claim 1 or 6 wherein said composite signal is a subband signal that corresponds to a respective frequency subband, and wherein said method further comprises normalizing information conveyed by said composite signal with respect to a measure of signal level for a channel subband signal in that respective frequency subband having the largest measure.
Claim 17
Dependent Claim
57 words
A method according to claim 1 or 6 that further comprises generating a differential-encoded representation of said spatial-characteristics signals corresponding to a plurality of adjacent frequency subbands, wherein said differential-encoded representation comprises one or more codes having a dynamic range that is limited according to spectral leakage characteristics between said channel subband signals in adjacent frequency subbands.
Claim 18
Independent Claim
157 words
A method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 19
Independent Claim
157 words
A method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 20
Independent Claim
237 words
A method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, deriving from said spatial-characteristics signals a plurality of gain factors and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 21
Independent Claim
237 words
A method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, deriving from said spatial-characteristics signals a plurality of gain factors and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 22
Dependent Claim
30 words
A method according to claim 17 wherein rates of decrease in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 23
Dependent Claim
30 words
A method according to claim 16 or 17 wherein said composite subband signals are derived by applying a filter bank or a transform to said one or more composite signals.
Claim 24
Dependent Claim
30 words
A method according to claim 16 or 17 wherein said composite signal is a parametric signal and said deriving comprises generating a spectral or a temporal signal in response thereto.
Claim 25
Dependent Claim
34 words
A method according to claim 16 or 17 that further comprises obtaining from said encoded signal a delay signal and delaying the mapping of said respective composite signal in response to said delay signal.
Claim 26
Dependent Claim
27 words
A method according to claim 16 or 17 wherein said interim subband signals have bandwidths that are commensurate with the critical-band bandwidths of a human auditory system.
Claim 27
Dependent Claim
63 words
A method according to claim 16 or 17 wherein said output signals are generated by applying an inverse filter bank having aliasing cancellation properties or by applying an inverse transform having aliasing cancellation properties, and wherein said mapping limits differences between levels of said interim subband signals in adjacent frequency subbands such that noise resulting from incomplete aliasing cancellation is rendered substantially inaudible.
Claim 28
Independent Claim
172 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and in a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 29
Independent Claim
172 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and in a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 30
Dependent Claim
51 words
A medium according to claim 24 wherein said method is such that, in response to said respective channel subband signals in a respective frequency subband, said spatial-characteristics signal is generated in said first form if said soundfield is deemed to have a number of apparent directions greater than a threshold number.
Claim 31
Dependent Claim
60 words
A medium according to claim 25 wherein said method is such that said threshold number is one and said soundfield is deemed to have one apparent direction when only one of said respective channel subband signals has significant spectral energy or when all of said respective channel subband signals having significant spectral energy also have correlated amplitudes and correlated phases.
Claim 32
Dependent Claim
36 words
A medium according to claim 24 wherein said method is such that said respective spatial-characteristics signal is generated in said second form such that it also represents a measure of soundfield dispersion about an intended direction.
Claim 33
Dependent Claim
49 words
A medium according to claim 24 wherein said method is such that said spatial-characteristics signal is generated in said first form such that rates of decrease in values of said information representing said signal levels are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 34
Independent Claim
136 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 35
Independent Claim
136 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said method comprising: generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, generating a composite signal representing at least a portion of the bandwidth of said input signals, generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 36
Dependent Claim
32 words
A medium according to claim 24 or 29 wherein said method is such that said composite signal is generated by combining two or more channel subband signals in a respective frequency subband.
Claim 37
Dependent Claim
51 words
A medium according to claim 24 or 29 wherein said method is such that said composite signal is a subband signal that is generated by applying a filter bank or a transform to a wideband signal, wherein said wideband signal is formed by combining two or more of said input signals.
Claim 38
Dependent Claim
42 words
A medium according to claim 24 or 29 wherein said method is such that said composite signal is generated by combining subband signals that are obtained by applying a filter bank or a transform to two or more of said input signals.
Claim 39
Dependent Claim
21 words
A medium according to claim 24 or 29 wherein said method is such that said composite signal is a parametric signal.
Claim 40
Dependent Claim
43 words
A medium according to claim 29 wherein said method is such that said spatial-characteristic signal represents one or more intended directions and rates of change in the spatial-characteristic signal are limited to control a rate at which said intended directions can change orientation.
Claim 41
Dependent Claim
49 words
A medium according to claim 29 wherein said method is such that said spatial-characteristic signal conveys information representing signal levels of said respective channel subband signals and said rates of change in the spatial-characteristic signal correspond to rates of decrease in values of said information representing the signal levels.
Claim 42
Dependent Claim
72 words
A medium according to claim 24 or 29 wherein said method is such that each of said respective channel subband signals is generated in response to a common time interval of said input signals, and wherein said method further comprises generating a delay signal indicating where in said common time interval an abrupt change in amplitude or direction occurs in said respective soundfield, and assembling said delay signal into said encoded signal.
Claim 43
Dependent Claim
63 words
A medium according to claim 24 or 29 wherein said method is such that said composite signal is a subband signal that corresponds to a respective frequency subband, and wherein said method further comprises normalizing information conveyed by said composite signal with respect to a measure of signal level for a channel subband signal in that respective frequency subband having the largest measure.
Claim 44
Dependent Claim
59 words
A medium according to claim 24 or 29 wherein said method further comprises generating a differential-encoded representation of said spatial-characteristics signals corresponding to a plurality of adjacent frequency subbands, wherein said differential-encoded representation comprises one or more codes having a dynamic range that is limited according to spectral leakage characteristics between said channel subband signals in adjacent frequency subbands.
Claim 45
Independent Claim
174 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 46
Independent Claim
174 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 47
Independent Claim
254 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, deriving from said spatial-characteristics signals a plurality of gain factors and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 48
Independent Claim
254 words
A medium readable by a machine, embodying a program of instructions executable by said machine to perform a method for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said method comprising: obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, deriving from said spatial-characteristics signals a plurality of gain factors and mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 49
Dependent Claim
35 words
A medium according to claim 40 wherein said method is such that rates of decrease in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 50
Dependent Claim
35 words
A medium according to claim 39 or 40 wherein said method is such that said composite subband signals are derived by applying a filter bank or a transform to said one or more composite signals.
Claim 51
Dependent Claim
35 words
A medium according to claim 39 or 40 wherein said method is such that said composite signal is a parametric signal and said deriving comprises generating a spectral or a temporal signal in response thereto.
Claim 52
Dependent Claim
36 words
A medium according to claim 39 or 40 wherein said method further comprises obtaining from said encoded signal a delay signal and delaying the mapping of said respective composite signal in response to said delay signal.
Claim 53
Dependent Claim
32 words
A medium according to claim 39 or 40 wherein said method is such that said interim subband signals have bandwidths that are commensurate with the critical-band bandwidths of a human auditory system.
Claim 54
Dependent Claim
68 words
A medium according to claim 39 or 40 wherein said method is such that said output signals are generated by applying an inverse filter bank having aliasing cancellation properties or by applying an inverse transform having aliasing cancellation properties, and wherein said mapping limits differences between levels of said interim subband signals in adjacent frequency subbands such that noise resulting from incomplete aliasing cancellation is rendered substantially inaudible.
Claim 55
Dependent Claim
163 words
An encoder for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said encoder comprising: means for generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, means for generating a composite signal representing at least a portion of the bandwidth of said input signals, means for generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and in a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and means for assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 56
Dependent Claim
163 words
An encoder for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said encoder comprising: means for generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, means for generating a composite signal representing at least a portion of the bandwidth of said input signals, means for generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein said spatial-characteristic signal is generated in either or both of a first form conveying information representing signal levels of said respective channel subband signals and in a second form representing one or more intended directions, wherein the forms in which to generate said spatial-characteristics signal are determined adaptively, and means for assembling said composite signal, said spatial-characteristics signal and an indication of the form of said spatial-characteristics signal into said encoded signal.
Claim 57
Dependent Claim
46 words
An encoder according to claim 47 where, in response to said respective channel subband signals in a respective frequency subband, said spatial-characteristics signal is generated in said first form if said soundfield is deemed to have a number of apparent directions greater than a threshold number.
Claim 58
Dependent Claim
55 words
An encoder according to claim 48 wherein said threshold number is one and said soundfield is deemed to have one apparent direction when only one of said respective channel subband signals has significant spectral energy or when all of said respective channel subband signals having significant spectral energy also have correlated amplitudes and correlated phases.
Claim 59
Dependent Claim
31 words
An encoder according to claim 47 wherein said respective spatial-characteristics signal is generated in said second form such that it also represents a measure of soundfield dispersion about an intended direction.
Claim 60
Dependent Claim
44 words
An encoder according to claim 47 wherein said spatial-characteristics signal is generated in said first form such that rates of decrease in values of said information representing said signal levels are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 61
Dependent Claim
127 words
An encoder for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said encoder comprising: means for generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, means for generating a composite signal representing at least a portion of the bandwidth of said input signals, means for generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and means for assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 62
Dependent Claim
127 words
An encoder for generating an encoded signal by encoding a plurality of input signals each representing a respective channel of audio information, said encoder comprising: means for generating a plurality of channel subband signals representing said input signals in a plurality of frequency subbands, means for generating a composite signal representing at least a portion of the bandwidth of said input signals, means for generating a spatial-characteristic signal representing spatial characteristics of a soundfield associated with said composite signal in response to respective channel subband signals in a frequency subband, wherein rates of change in said spatial-characteristic signal are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and means for assembling said composite signal and said spatial-characteristics signal into said encoded signal.
Claim 63
Dependent Claim
29 words
An encoder according to claim 47 or 52 further comprising means for combining two or more channel subband signals in a respective frequency subband to generate said composite signal.
Claim 64
Dependent Claim
44 words
An encoder according to claim 47 or 52 further comprising means for generating a wideband signal by combining two or more of said input signals, and means for generating said composite signal by applying a filter bank or a transform to said wideband signal.
Claim 65
Dependent Claim
49 words
An encoder according to claim 47 or 52 further comprising means for applying a filter bank or a transform to two or more of said input signals and means for generating said composite signal by combining subband signals that are obtained by applying said filter bank or said transform.
Claim 66
Dependent Claim
16 words
An encoder according to claim 47 or 52 wherein said composite signal is a parametric signal.
Claim 67
Dependent Claim
38 words
An encoder according to claim 52 wherein said spatial-characteristic signal represents one or more intended directions and rates of change in the spatial-characteristic signal are limited to control a rate at which said intended directions can change orientation.
Claim 68
Dependent Claim
44 words
An encoder according to claim 52 wherein said spatial-characteristic signal conveys information representing signal levels of said respective channel subband signals and said rates of change in the spatial-characteristic signal correspond to rates of decrease in values of said information representing the signal levels.
Claim 69
Dependent Claim
71 words
An encoder according to claim 47 or 52 wherein each of said respective channel subband signals is generated in response to a common time interval of said input signals, and wherein said encoder further comprises means for generating a delay signal indicating where in said common time interval an abrupt change in amplitude or direction occurs in said respective soundfield, and means for assembling said delay signal into said encoded signal.
Claim 70
Dependent Claim
60 words
An encoder according to claim 47 or 52 wherein said composite signal is a subband signal that corresponds to a respective frequency subband, and wherein said encoder further comprises means for normalizing information conveyed by said composite signal with respect to a measure of signal level for a channel subband signal in that respective frequency subband having the largest measure.
Claim 71
Dependent Claim
58 words
An encoder according to claim 47 or 52 further comprising means for generating a differential-encoded representation of said spatial-characteristics signals corresponding to a plurality of adjacent frequency subbands, wherein said differential-encoded representation comprises one or more codes having a dynamic range that is limited according to spectral leakage characteristics between said channel subband signals in adjacent frequency subbands.
Claim 72
Dependent Claim
165 words
A decoder for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said decoder comprising: means for obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and for deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, means for deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and for mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and means for generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 73
Dependent Claim
165 words
A decoder for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said decoder comprising: means for obtaining from said encoded signal one or more composite signals and a plurality of spatial-characteristics signals, and for deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, means for deriving from said spatial-characteristics signals a plurality of gain factors, wherein rates of change in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system, and for mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor, and means for generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 74
Dependent Claim
245 words
A decoder for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said decoder comprising: means for obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and for deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, means for deriving from said spatial-characteristics signals a plurality of gain factors and for mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and means for generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 75
Dependent Claim
245 words
A decoder for decoding an encoded signal to generate one or more output signals for presentation via one or more output transducers, said decoder comprising: means for obtaining from said encoded signal one or more composite signals, a plurality of spatial-characteristics signals and an indication of the form of said spatial-characteristics signals, and for deriving a plurality of composite subband signals from said one or more composite signals, wherein each spatial-characteristics signal is associated with a respective composite subband signal and represents spatial characteristics of a respective soundfield corresponding to said respective composite subband signal, wherein said indication indicates whether said spatial-characteristics signals are in a first form representing a plurality of signal levels and/or are in a second form representing one or more directions, means for deriving from said spatial-characteristics signals a plurality of gain factors and for mapping a respective composite subband signal into one or more interim subband signals according to a respective gain factor wherein, for said associated spatial-characteristic signal having said first form, said mapping is also according to a spatial configuration signal associated with said signal levels and a transducer configuration signal representing a spatial configuration of said output transducers, and wherein, for said associated spatial-characteristic signal having said second form, said mapping is also according to said one or more directions and said transducer configuration signal, and means for generating said plurality of output signals by applying one or more inverse filter banks to said interim subband signals.
Claim 76
Dependent Claim
30 words
A decoder according to claim 63 wherein rates of decrease in values of said gain factors are limited to be commensurate with temporal post-masking characteristics of a human auditory system.
Claim 77
Dependent Claim
32 words
A decoder according to claim 62 or 63 further comprising means for applying a filter bank or a transform to said one or more composite signals to derive said composite subband signals.
Claim 78
Dependent Claim
34 words
A decoder according to claim 62 or 63 wherein said composite signal is a parametric signal and said means for deriving is also for generating a spectral or a temporal signal in response thereto.
Claim 79
Dependent Claim
36 words
A decoder according to claim 62 or 63 further comprising means for obtaining from said encoded signal a delay signal and for delaying the mapping of said respective composite signal in response to said delay signal.
Claim 80
Dependent Claim
27 words
A decoder according to claim 62 or 63 wherein said interim subband signals have bandwidths that are commensurate with the critical-band bandwidths of a human auditory system.
Claim 81
Dependent Claim
64 words
A decoder according to claim 62 or 63 further comprising means for applying an inverse filter bank having aliasing cancellation properties or an inverse transform having aliasing cancellation properties to generate said output signals, wherein said means for mapping limits differences between levels of said interim subband signals in adjacent frequency subbands such that noise resulting from incomplete aliasing cancellation is rendered substantially inaudible.
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USPTO Annuity & Maintenance Windows
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