Low complexity decoder for complex transform coding of multi-channel sound
AssigneeMicrosoft Corporation
InventorsSanjeev Mehrotra, Wei-Ge Chen
Life of this patent
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Abstract
A multi-channel audio decoder provides a reduced complexity processing to reconstruct multi-channel audio from an encoded bitstream in which the multi-channel audio is represented as a coded subset of the channels along with a complex channel correlation matrix parameterization. The decoder translates the complex channel correlation matrix parameterization to a real transform that satisfies the magnitude of the complex channel correlation matrix. The multi-channel audio is derived from the coded subset of channels via channel extension processing using a real value effect signal and real number scaling.
Claims46
A method of decoding multi-channel audio, the method comprising:
- decoding a set of cross-channel correlation and channel power parameters from an encoded audio stream;
- deriving a real number matrix transform from the set of cross-channel correlation and channel power parameters that satisfies a magnitude of cross-channel correlation;
- reconstructing spectral coefficients of a coded subset of channels of the multi-channel audio;
- with a processing unit, performing channel extension processing from the reconstructed spectral coefficients of the coded subset of channels based on the real number matrix transform to reconstruct spectral coefficients of the channels of the multi-channel audio;
- and
- applying an inverse time-frequency transform to reconstruct the multi-channel audio.
A method of decoding multi-channel audio, the method comprising:
- decoding a set of cross-channel correlation and channel power parameters from an encoded audio stream;
- deriving a real number matrix transform from the set of cross-channel correlation and channel power parameters that satisfies a magnitude of cross-channel correlation;
- reconstructing spectral coefficients of a coded subset of channels of the multi-channel audio;
- with a processing unit, performing channel extension processing from the reconstructed spectral coefficients of the coded subset of channels based on the real number matrix transform to reconstruct spectral coefficients of the channels of the multi-channel audio;
- and
- applying an inverse time-frequency transform to reconstruct the multi-channel audio, wherein:
- the set of cross-channel correlation and channel power parameters characterize a complex channel correlation matrix, and
- the set of cross-channel correlation and channel power parameters comprise an LMRM parameterization of the complex channel correlation matrix.
A multi-channel audio decoder, comprising:
- an input for receiving an encoded audio stream;
- a processing unit configured to reconstruct multi-channel audio from the encoded audio stream via:
- decoding a set of cross-channel correlation and channel power parameters from the encoded audio stream;
- deriving a real number matrix transform from the set of cross-channel correlation parameters that satisfies a magnitude of cross-channel correlation;
- reconstructing spectral coefficients of a coded subset of channels of the multi-channel audio;
- performing channel extension processing from the reconstructed spectral coefficients of the coded subset of channels based on the real number matrix transform to reconstruct spectral coefficients of the channels of the multi-channel audio;
- and
- applying an inverse time-frequency transform to reconstruct the multi-channel audio.
A method of encoding multi-channel audio, the method comprising:
- encoding a subset of channels of the multi-channel audio in an encoded bitstream;
- with a processing unit, encoding parameters characterizing a complex channel correlation matrix in the encoded bitstream;
- encoding a plurality of syntax elements for channel extension processing at decoding into the encoded bitstream, the syntax elements comprising at least the following:
- a first syntax element representing a value at which to cap an effect signal for channel extension processing;
- a second syntax element indicative of whether power adjustment scaling is applied;
- a third syntax element representing a value at which a scale factor for channel extension processing is capped;
- and
- a fourth syntax element indicative of which filter tap of a reverb filter generates an effect signal for channel extension processing.
Computer-readable memory or storage storing computer-readable instructions that when executed by a computer cause the computer to perform a method of decoding multi-channel audio, the method comprising:
- decoding a set of cross-channel correlation and channel power parameters from an encoded audio stream;
- deriving a real number matrix transform from the set of cross-channel correlation and channel power parameters that satisfies a magnitude of cross-channel correlation;
- reconstructing spectral coefficients of a coded subset of channels of the multi-channel audio;
- performing channel extension processing from the reconstructed spectral coefficients of the coded subset of channels based on the real number matrix transform to reconstruct spectral coefficients of the channels of the multi-channel audio;
- and
- applying an inverse time-frequency transform to reconstruct the multi-channel audio.
Computer-readable memory or storage storing computer-readable instructions that when executed by a computer cause the computer to perform a method of decoding multi-channel audio, the method comprising:
- decoding a set of cross-channel correlation and channel power parameters from an encoded audio stream;
- deriving a real number matrix transform from the set of cross-channel correlation and channel power parameters that satisfies a magnitude of cross-channel correlation;
- reconstructing spectral coefficients of a coded subset of channels of the multi-channel audio;
- performing channel extension processing from the reconstructed spectral coefficients of the coded subset of channels based on the real number matrix transform to reconstruct spectral coefficients of the channels of the multi-channel audio;
- and
- applying an inverse time-frequency transform to reconstruct the multi-channel audio, wherein:
- the set of cross-channel correlation and channel power parameters characterize a complex channel correlation matrix, and
- the set of cross-channel correlation and channel power parameters comprise an LMRM parameterization of the complex channel correlation matrix.
Computer-readable memory or storage storing computer-readable instructions that when executed by a computer cause the computer to perform a method of encoding multi-channel audio, the method comprising:
- encoding a subset of channels of the multi-channel audio in an encoded bitstream;
- encoding parameters characterizing a complex channel correlation matrix in the encoded bitstream;
- encoding a plurality of syntax elements for channel extension processing at decoding into the encoded bitstream, the syntax elements comprising at least the following:
- a first syntax element representing a value at which to cap an effect signal for channel extension processing;
- a second syntax element indicative of whether power adjustment scaling is applied;
- a third syntax element representing a value at which a scale factor for channel extension processing is capped;
- and
- a fourth syntax element indicative of which filter tap of a reverb filter generates an effect signal for channel extension processing.
Dependencies are inferred from the claim text.