Patent ID: 8494864

Claim:
A method for coding an input signal in an encoder system, wherein the method comprises the steps of: applying a first mode to the input audio signal (X) to form a first output (Y 1 ); applying a second mode to the input audio signal (X) to form a second output (Y 2 ); forming a first processed output (Y 1,proc ) from at least a part of the first output (Y 1 ), and a second processed output (Y 2,proc ) from at least a part of the second output (Y 2 ), wherein forming a second processed output comprises estimating a part of the input signal from at least a part of the second output (Y 2 ); determining an optimum mode based on the first processed output (Y 1,proc ) and the second processed output (Y 2,proc ), and on a selection criterion calculated from the input signal and the processed outputs, wherein the selection criterion is defined as a minimization problem given as: m (*) =arg min m D ( X , Y m,proc ); where m (*) is the optimum mode m, D is the distortion, m=(1, . . . , M) is the index over M modes or m is the index over a subset of M modes, X =(x 0 , . . . , x N-1 ) is the input signal, and Y =(y 0 , . . . , y N-1 ) m,proc is the processed output for mode, wherein the distortion D for at least one mode is given by: D = 1 N ⁢ ∑ n = 0 N - 1 ⁢ ⁢ ( x n * - y n * ) β n , wherein N is the number of coefficients in the input signal, x 0 * =  x 0  ⁢ ⁢ and ⁢ ⁢ x n * = ( 1 - α n ) ⁢  x n  + α n ⁢ x n - 1 * ⁢ ⁢ for ⁢ ⁢ all ⁢ ⁢ 1 ≤ n < N , ⁢ y 0 * =  y 0  ⁢ ⁢ and ⁢ ⁢ y n * = ( 1 - α n ) ⁢  y n  + α n ⁢ y n - 1 * ⁢ ⁢ for ⁢ ⁢ all ⁢ ⁢ 1 ≤ n < N , ⁢ α n = ( n N ) 6 , and ⁢ ⁢ β n = { 4 , if ⁢ ⁢ ( x n * - y n * ) < 0 2 , if ⁢ ⁢ ( x n * - y n * ) ≥ 0 ; and selecting the output (Y 1 , Y 2 ) according to the optimum mode.