Patent ID: 8705749

Claim:
A method for reformatting a plurality [NI] of audio input signals [Input 1 (t) . . . Input N1 (t)] from a first format to a second format by applying them to a dynamically-varying transformatting matrix [M], in which the plurality of audio input signals are assumed to have been derived by applying a plurality of notional source signals [Source 1 (t) . . . Source NS (t)], each associated with information about itself, to an encoding matrix [ 1 ], the encoding matrix processing the notional source signals in accordance with a first rule that processes each notional source signal in accordance with the notional information associated with it, the transformatting matrix being controlled so that differences are reduced between a plurality [NO] of output signals [Output 1 (t) . . . Output NO (t)] produced by it and a plurality [NO] of notional ideal output signals [IdealOut 1 (t) . . . IdealOut NO (t)] assumed to have been derived by applying the notional source signals to an ideal decoding matrix [O], the decoding matrix processing the notional source signals in accordance with a second rule that processes each notional source signal in accordance with the notional information associated with it, comprising obtaining, in response to the audio input signals in each of a plurality of frequency and time segments, information attributable to the direction and intensity of one or more directional signal components and to the intensity of a diffuse, non-directional signal component, calculating the transformatting matrix based on the first and second rules, said calculating including (a) estimating (i) a covariance matrix of the audio input signals in at least one of said plurality of frequency and time segments and (ii) a cross-covariance matrix of the audio input signals and the notional ideal output signals in the same at least one of said plurality of frequency and time segments, and (b) combining, in a plurality of said frequency and time segments, (i) said directions and intensities of dominant signal components and (ii) said intensities of diffuse, non-directional signal components, and applying the audio input signals to the transformatting matrix to produce said output signals.