Complex cross-correlation parameters for multi-channel audio
First Claim
1. In an audio encoder, a computer-implemented method comprising:
- encoding a combined channel for a group of plural physical audio channels; and
determining plural parameters for representing individual physical channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise;
ratios of power in each of at least two of the individual channels to power in the combined channel; and
a cross-correlation parameter representing a cross-correlation ratio, the cross-correlation ratio representable at a decoder by an imaginary number component and a real number component, the cross-correlation parameter representing cross-correlation between channels, wherein the imaginary number component comprises an imaginary number component of a correlation matrix.
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Abstract
An audio encoder encodes a combined channel (e.g., a sum channel) for a group of plural physical audio channels. The encoder determines plural parameters for representing individual physical channels of the group as modified versions of the encoded combined channel. The plural parameters comprise ratios of power in each individual channel to power in the combined channel (e.g., a ratio of the power of a right channel to the power of the combined channel, and a ratio of the power of the left channel to the power of the combined channel). The plural parameters can include a complex parameter. The combined channel and the plural parameters facilitate reconstruction at the audio decoder of source channels. An audio decoder performs a forward complex transform on the multi-channel audio data and reconstructs plural channels from the multi-channel audio data. The decoder can maintain second-order statistics for the source channels.
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Citations
28 Claims
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1. In an audio encoder, a computer-implemented method comprising:
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encoding a combined channel for a group of plural physical audio channels; and determining plural parameters for representing individual physical channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise; ratios of power in each of at least two of the individual channels to power in the combined channel; and a cross-correlation parameter representing a cross-correlation ratio, the cross-correlation ratio representable at a decoder by an imaginary number component and a real number component, the cross-correlation parameter representing cross-correlation between channels, wherein the imaginary number component comprises an imaginary number component of a correlation matrix. - View Dependent Claims (2, 3, 4, 5, 6, 7, 22, 23, 27, 28)
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8. A computer-readable storage device storing computer-executable instructions for causing a computer programmed thereby to perform the method comprising:
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encoding a combined channel for a group of plural physical audio channels; and determining plural parameters for representing individual physical channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise; ratios of power in each of at least two of the individual channels to power in the combined channel; and a cross-correlation parameter representing a cross-correlation ratio, the cross-correlation ratio representable at a decoder by an imaginary number component and a real number component, the cross-correlation parameter representing cross-correlation between channels, wherein the imaginary number component comprises an imaginary number component of a correlation matrix.
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9. In an audio encoder, a computer-implemented method comprising:
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receiving multi-channel audio data, the multi-channel audio data comprising a group of plural channels; encoding a combined channel for the group; determining plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise at least one cross-correlation parameter representing a ratio that is representable at the audio decoder by an imaginary number component and a real number component, wherein the imaginary number component comprises an imaginary number component of a correlation matrix; and sending the encoded combined channel and the plural parameters to the audio decoder; wherein the encoded combined channel and the plural parameters facilitate reconstruction at the audio decoder of at least two of the plural source channels. - View Dependent Claims (10, 11, 12, 13, 14, 15, 24)
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16. A computer-readable storage device storing computer-executable instructions for causing a computer programmed thereby to perform the method comprising:
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receiving multi-channel audio data, the multi-channel audio data comprising a group of plural channels; encoding a combined channel for the group; determining plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise at least one cross-correlation parameter representing a ratio that is representable at the audio decoder by an imaginary number component and a real number component, wherein the imaginary number component comprises an imaginary number component of a correlation matrix; and sending the encoded combined channel and the plural parameters to the audio decoder; wherein the encoded combined channel and the plural parameters facilitate reconstruction at the audio decoder of at least two of the plural source channels.
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17. In an audio decoder, a computer-implemented method comprising:
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receiving encoded multi-channel audio data, the encoded multi-channel audio data comprising an encoded combined channel and plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise at least one cross-correlation parameter representing a ratio that is representable by an imaginary component and a real component, the ratio representing cross- channel correlation, wherein the imaginary component comprises an imaginary component of a correlation matrix; and decoding the encoded multi-channel audio data, wherein the decoding comprises; performing a forward complex transform on the multi-channel audio data; and reconstructing plural channels from the multi-channel audio data. - View Dependent Claims (18, 19, 21)
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20. A computer-readable storage device storing computer-executable instructions for causing a computer programmed thereby to perform the method comprising:
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receiving encoded multi-channel audio data, the encoded multi-channel audio data comprising an encoded combined channel and plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel, wherein the plural parameters comprise at least one cross-correlation parameter representing a ratio that is representable by an imaginary component and a real component, the ratio representing cross- channel correlation, wherein the imaginary component comprises an imaginary component of a correlation matrix; and decoding the encoded multi-channel audio data, wherein the decoding comprises; performing a forward complex transform on the multi-channel audio data; and reconstructing plural channels from the multi-channel audio data.
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25. In an audio decoder, a computer-implemented method comprising:
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receiving encoded multi-channel audio data in a bitstream, the encoded multi-channel audio data comprising channel extension coding data, wherein the channel extension coding data comprises a combined channel for the plural audio channels and plural parameters for representing individual channels of the plural audio channels as modified versions of the combined channel; determining based on bitstream syntax whether the plural parameters comprise (a) normalized correlation matrix parameters, or (b) plural power ratios and a complex parameter representing a ratio comprising an imaginary component and a real component of cross-correlation between two of the plural audio channels, wherein the imaginary component comprises an imaginary component of a correlation matrix; based on the determining, decoding the plural parameters; and reconstructing plural audio channels using the channel extension coding data. - View Dependent Claims (26)
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Specification