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US RE44,126 E1Granted
Coding techniques using estimated spectral magnitude and phase derived from MDCT coefficients
AssigneeDolby Laboratories Licensing Corporation
InventorsCorey I. Cheng, Michael J. Smithers, David N. Lathrop
Life of this patent
Estimating the term…
Abstract
Estimates of spectral magnitude and phase are obtained by an estimation process using spectral information from analysis filter banks such as the Modified Discrete Cosine Transform. The estimation process may be implemented by convolution-like operations with impulse responses. Portions of the impulse responses may be selected for use in the convolution-like operations to trade off between computational complexity and estimation accuracy. Mathematical derivations of analytical expressions for filter structures and impulse responses are disclosed.
Claims120
A method of processing information representing a source signal conveying content intended for human perception, the method comprising:
- receiving first spectral components that were generated by application of an analysis filterbank to the source signal, wherein the first spectral components represent spectral content of the source signal expressed in a first subspace of a multidimensional space;
- deriving one or more first intermediate components from at least some of the first spectral components, wherein at least some of the first intermediate components differ from the first spectral components from which they are derived;
- forming a combination of the one or more first intermediate components according to at least a portion of one or more impulse responses to obtain one or more second intermediate components;
- deriving one or more second spectral components from the one or more second intermediate components, wherein the second spectral components represent spectral content of the source signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace;
- obtaining estimated measures of magnitude or phase using the first spectral components and the second spectral components;
- and
- applying an adaptive process to the first spectral components to generate processed information, wherein the adaptive process is responsive to the estimated measures of magnitude or phase.
4 more elements
A medium conveying a program of instructions that is executable by a device to perform a method of processing information representing a source signal conveying content intended for human perception, the method comprising:
- receiving first spectral components that were generated by application of an analysis filterbank to the source signal, wherein the first spectral components represent spectral content of the source signal expressed in a first subspace of a multidimensional space;
- deriving one or more first intermediate components from at least some of the first spectral components, wherein at least some of the first intermediate components differ from the first spectral components from which they are derived;
- forming a combination of the one or more first intermediate components according to at least a portion of one or more impulse responses to obtain one or more second intermediate components;
- deriving one or more second spectral components from the one or more second intermediate components, wherein the second spectral components represent spectral content of the source signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace;
- obtaining estimated measures of magnitude or phase using the first spectral components and the second spectral components;
- and
- applying an adaptive process to the first spectral components to generate processed information, wherein the adaptive process is responsive to the estimated measures of magnitude or phase.
4 more elements
An apparatus for processing information representing a source signal conveying content intended for human perception, the apparatus comprising:
- means for receiving first spectral components that were generated by application of an analysis filterbank to the source signal, wherein the first spectral components represent spectral content of the source signal expressed in a first subspace of a multidimensional space;
- means for deriving one or more first intermediate components from at least some of the first spectral components, wherein at least some of the first intermediate components differ from the first spectral components from which they are derived;
- means for forming a combination of the one or more first intermediate components according to at least a portion of one or more impulse responses to obtain one or more second intermediate components;
- means for deriving one or more second spectral components from the one or more second intermediate components, wherein the second spectral components represent spectral content of the source signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace;
- means for obtaining estimated measures of magnitude or phase using the first spectral components and the second spectral components;
- and
- means for applying an adaptive process to the first spectral components to generate processed information, wherein the adaptive process is responsive to the estimated measures of magnitude or phase.
4 more elements
A method of processing information representing a source signal conveying content intended for human perception, the method comprising:
- generating first spectral components by application of a first analysis filterbank to the source signal;
- generating second spectral components from a convolution of a derivation of at least some of the first spectral components with a portion of one or more impulse responses of hypothetical filters related to the combined effect of a synthesis filterbank inverse to the first analysis filterbank and a second analysis filterbank coupled to the synthesis filterbank;
- generating estimated parameters using at least some of the first spectral components and at least some of the second spectral components;
- and
- generating audio information using at least some of the first spectral components, wherein the step of generating audio information is responsive to the estimated parameters;
- wherein the method is performed by one or more computing devices.
3 more elements
A non-transitory computer readable medium, storing instructions for processing information representing a source signal conveying content intended for human perception, which when executed by one or more processors cause performance of the steps of:
- receiving first spectral components that were generated by application of a first analysis filterbank to the source signal;
- obtaining second spectral components from a convolution of a derivation of at least some of the first spectral components with a portion of one or more impulse responses of hypothetical filters related to the combined effect of a synthesis filterbank inverse to the first analysis filterbank and a second analysis filterbank coupled to the synthesis filterbank;
- obtaining estimated parameters using the first spectral components and the second spectral components;
- and
- generating audio information using the first spectral components, wherein the generating step is responsive to the estimated parameters.
2 more elements
An apparatus for processing information representing a source signal conveying content intended for human perception, the apparatus comprising:
- a subsystem, implemented at least partially in hardware that receives first spectral components that were generated by application of a first analysis filterbank to the source signal;
- a subsystem, implemented at least partially in hardware that obtains second spectral components from a convolution of a derivation of at least some of the first spectral components with a portion of one or more impulse responses of hypothetical filters related to the combined effect of a synthesis filterbank inverse to the first analysis filterbank and a second analysis filterbank coupled to the synthesis filterbank;
- a subsystem, implemented at least partially in hardware that obtains estimated parameters using the first spectral components and the second spectral components;
- and
- a subsystem, implemented at least partially in hardware that generates audio information using the first spectral components, wherein the generating subsystem is responsive to the estimated parameters.
2 more elements
A decoder for decoding information representing a source signal conveying content intended for human perception, the decoder comprising:
- means for receiving first spectral components that were generated by application of a first analysis filterbank to the source signal;
- means for obtaining second spectral components from a convolution of a derivation of at least some of the first spectral components with a portion of one or more impulse responses of hypothetical filters related to the combined effect of a synthesis filterbank inverse to the first analysis filterbank and a second analysis filterbank coupled to the synthesis filterbank;
- means for obtaining estimated parameters using the first spectral components and the second spectral components;
- and
- means for generating audio information using the first spectral components, wherein the generating step is responsive to the estimated parameters.
2 more elements
Dependencies are inferred from the claim text.