Patent ID: 7639823

Claim:
A computer-implemented method for generating M output audio channels from N input audio channels, where N and M are positive integers, the method comprising: (a) the computer mixing the N input channels to generate M mixed channels; and (b) the computer equalizing the M mixed channels to generate the M output channels, wherein: for a first set of one or more frequency sub-bands, step (b) comprises scaling the amplitude of each of the M mixed channels such that an amplitude sum magnitude for the M output channels is substantially equal to an amplitude sum magnitude for the N input channels; and for each frequency sub-band in the first set, step (b) comprises: (1) the computer estimating the amplitude of each of the N input channels; (2) the computer estimating the amplitude of each of the M mixed channels; (3) the computer generating scale factors based on the estimated amplitudes of the input and mixed channels; and (4) the computer applying the scale factors to the M mixed channels to generate the M output channels, wherein the scale factors are derived from binaural cue codes (BCCs) generated in a BCC encoder and applied in a BCC decoder.