Coding of a sound field signal
First Claim
1. An adaptive audio encoding device, comprising:
- a spatial analyzer configured to receive a plurality of audio signals and to determine, based on the plurality of audio signals, frame-wise decomposition parameters;
an adaptive rotation stage configured to receive said plurality of audio signals and to output at least a first, second, and third rotated audio signal obtained by an energy-compacting orthogonal transformation, wherein quantitative properties of the transformation are determined by the decomposition parameters;
a spectral envelope analyzer configured to receive a frequency-domain representation of the rotated audio signals, which contains transform coefficients, and to output, based thereon, a spectral envelope; and
a multichannel encoder configured to receive the frequency-domain representation of the rotated audio signals and to output transform coefficients of the first rotated audio signal only for frequency subbands in a first subband collection, transform coefficients of the second rotated audio signal only for frequency subbands in a second subband collection, and transform coefficients of the third rotated audio signal only for frequency subbands in a third subband collection, wherein any subbands not included in any subband collection are to be synthesized at decoding,wherein the multichannel encoder determines the first subband collection, the second subband collection, and the third subband collection by means of a rate allocation process based on a joint comparison of a noise profile for the rotated audio signals and the spectral envelopes of the rotated audio signals,wherein at least one of the spatial analyser, the adaptive rotation stage, the spectral envelope analyser, and the multichannel encoder, are implemented, at least in part, by one or more hardware elements of the adaptive audio encoding device.
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Abstract
A method for encoding sound field signals includes allocating coding rate by application of a uniform criterion to all subbands of all signals in a joint process. An allocation criterion may be based on a comparison, in a given subband, between a spectral envelope of the signals to be encoded and a coding noise profile, wherein the noise profile may be a sum of a noise shape and a noise offset, which noise offset is computed on the basis of the coding bit budget. The rate allocation process may be combined with an energy-compacting orthogonal transform, for which there is proposed a parameterization susceptible of efficient coding and having adjustable directivity. In a further aspect, the invention provides a corresponding decoding method.
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Citations
20 Claims
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1. An adaptive audio encoding device, comprising:
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a spatial analyzer configured to receive a plurality of audio signals and to determine, based on the plurality of audio signals, frame-wise decomposition parameters; an adaptive rotation stage configured to receive said plurality of audio signals and to output at least a first, second, and third rotated audio signal obtained by an energy-compacting orthogonal transformation, wherein quantitative properties of the transformation are determined by the decomposition parameters; a spectral envelope analyzer configured to receive a frequency-domain representation of the rotated audio signals, which contains transform coefficients, and to output, based thereon, a spectral envelope; and a multichannel encoder configured to receive the frequency-domain representation of the rotated audio signals and to output transform coefficients of the first rotated audio signal only for frequency subbands in a first subband collection, transform coefficients of the second rotated audio signal only for frequency subbands in a second subband collection, and transform coefficients of the third rotated audio signal only for frequency subbands in a third subband collection, wherein any subbands not included in any subband collection are to be synthesized at decoding, wherein the multichannel encoder determines the first subband collection, the second subband collection, and the third subband collection by means of a rate allocation process based on a joint comparison of a noise profile for the rotated audio signals and the spectral envelopes of the rotated audio signals, wherein at least one of the spatial analyser, the adaptive rotation stage, the spectral envelope analyser, and the multichannel encoder, are implemented, at least in part, by one or more hardware elements of the adaptive audio encoding device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An adaptive audio encoding method, comprising:
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determining frame-wise decomposition parameters on the basis of a plurality of audio signals; rotating the audio signals into at least a first, second, and third rotated audio signal using an energy-compacting orthogonal transformation, wherein quantitative properties of the transformation are determined by the decomposition parameters; computing a spectral envelope based on a frequency-domain representation of the rotated audio signals, which frequency-domain representation contains transform coefficients; determining a first, second, and third subband collection associated with a respective one of the first, second, and third rotated audio signals by means of a rate allocation process based on a joint comparison of a noise profile for all rotated audio signals and spectral envelopes of all rotated audio signals; and outputting transform coefficients of the first rotated audio signal only for frequency subbands in the first subband collection, transform coefficients of the second rotated audio signal only for frequency subbands in the second subband collection, and transform coefficients of the third rotated audio signal only for frequency subbands in the third subband collection, wherein any subbands not included in any subband collection are to be synthesized at decoding.
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14. An adaptive audio decoding device, comprising:
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a multichannel decoder configured to receive transform coefficients relating to a plurality of rotated audio signals and to output, based thereon, restored rotated audio signals; an adaptive rotation inversion stage configured to receive decomposition parameters and the restored rotated audio signals and to output, based thereon, at least three de-rotated audio signals, wherein the adaptive rotation inversion stage computes an inverse of a decomposition matrix on the basis of the decomposition parameters and forms a linear combination of the restored rotated audio signals with coefficients proportional to the elements of said inverse, wherein at least one of the multichannel decoder and the adaptive rotation inversion stage, are implemented, at least in part, by one or more hardware elements of the adaptive audio decoding device. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification