Complex-transform channel coding with extended-band frequency coding

摘要

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.

主权项

1. In an audio encoder, a computer-implemented method comprising:
receiving multi-channel audio data, the multi-channel audio data comprising a group of plural source channels; performing channel extension coding on the multi-channel audio data, the channel extension coding comprising:
encoding a combined channel for the group; anddetermining plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel, the plural parameters comprising a parameter representing a ratio of an imaginary part of cross-correlation between the individual source channels to a real part of cross-correlation between the individual source channels; and performing frequency extension coding on the multi-channel audio data.