Complex-transform channel coding with extended-band frequency coding
First Claim
1. In an audio decoder, a computer-implemented method of decoding encoded multi-channel audio data, the method comprising:
- receiving channel extension coding data comprising;
a combined audio channel;
plural power ratios representing power of individual audio channels relative to the combined audio channel; and
a complex parameter representing an imaginary-to-real ratio of cross-correlation between the individual audio channels;
receiving frequency extension coding data comprising scale and shape parameters for representing extended-band coefficients as scaled versions of baseband coefficients; and
reconstructing the individual audio channels using the channel extension coding data and the frequency extension coding data;
wherein the reconstructing comprises performing a real portion of a forward channel extension transform followed by frequency extension processing, and wherein the reconstructing further comprises deriving an imaginary portion of the forward channel extension transform after the frequency extension processing.
2 Assignments
0 Petitions
Accused Products
Abstract
An audio encoder receives multi-channel audio data comprising a group of plural source channels and performs channel extension coding, which comprises encoding a combined channel for the group and determining plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel. The encoder also performs frequency extension coding. The frequency extension coding can comprise, for example, partitioning frequency bands in the multi-channel audio data into a baseband group and an extended band group, and coding audio coefficients in the extended band group based on audio coefficients in the baseband group. The encoder also can perform other kinds of transforms. An audio decoder performs corresponding decoding and/or additional processing tasks, such as a forward complex transform.
165 Citations
22 Claims
-
1. In an audio decoder, a computer-implemented method of decoding encoded multi-channel audio data, the method comprising:
-
receiving channel extension coding data comprising; a combined audio channel; plural power ratios representing power of individual audio channels relative to the combined audio channel; and a complex parameter representing an imaginary-to-real ratio of cross-correlation between the individual audio channels; receiving frequency extension coding data comprising scale and shape parameters for representing extended-band coefficients as scaled versions of baseband coefficients; and reconstructing the individual audio channels using the channel extension coding data and the frequency extension coding data; wherein the reconstructing comprises performing a real portion of a forward channel extension transform followed by frequency extension processing, and wherein the reconstructing further comprises deriving an imaginary portion of the forward channel extension transform after the frequency extension processing. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. In an audio decoder, a computer-implemented method of decoding encoded multi-channel audio data, the method comprising:
-
receiving channel extension coding data comprising; a combined audio channel; plural power ratios representing power of individual audio channels relative to the combined audio channel; and a complex parameter representing an imaginary-to-real ratio of cross-correlation between the individual audio channels; receiving frequency extension coding data comprising scale and shape parameters for representing extended-band coefficients as scaled versions of baseband coefficients; and reconstructing the individual audio channels using the channel extension coding data and the frequency extension coding data; wherein the reconstructing comprises performing a real portion of a forward channel extension transform followed by frequency extension processing, wherein the forward channel extension transform is a modulated complex lapped transform comprising the real portion and an imaginary portion, and wherein the real portion is used for frequency extension coding. - View Dependent Claims (8, 9, 10, 11)
-
-
12. One or more tangible computer-readable media storing computer-executable instructions for causing a computer programmed thereby to perform a method of decoding encoded multi-channel audio data, the method comprising:
-
receiving channel extension coding data comprising; a combined audio channel; plural power ratios representing power of individual audio channels relative to the combined audio channel; and a complex parameter representing an imaginary-to-real ratio of cross-correlation between the individual audio channels; receiving frequency extension coding data comprising scale and shape parameters for representing extended-band coefficients as scaled versions of baseband coefficients; and reconstructing the individual audio channels using the channel extension coding data and the frequency extension coding data; wherein the reconstructing comprises performing a real portion of a forward channel extension transform followed by frequency extension processing, and wherein the reconstructing further comprises deriving an imaginary portion of the forward channel extension transform after the frequency extension processing. - View Dependent Claims (13, 14, 15, 16, 17)
-
-
18. One or more tangible computer-readable media storing computer-executable instructions for causing a computer programmed thereby to perform a method of decoding encoded multi-channel audio data, the method comprising:
-
receiving channel extension coding data comprising; a combined audio channel; plural power ratios representing power of individual audio channels relative to the combined audio channel; and a complex parameter representing an imaginary-to-real ratio of cross-correlation between the individual audio channels; receiving frequency extension coding data comprising scale and shape parameters for representing extended-band coefficients as scaled versions of baseband coefficients; and reconstructing the individual audio channels using the channel extension coding data and the frequency extension coding data; wherein the reconstructing comprises performing a real portion of a forward channel extension transform followed by frequency extension processing, wherein the forward channel extension transform is a modulated complex lapped transform comprising the real portion and an imaginary portion, and wherein the real portion is used for frequency extension coding. - View Dependent Claims (19, 20, 21, 22)
-
Specification