Patent ID: 7512536

Claim:
A method of filter bank operation, comprising the steps of: (a) receiving a block of subband coefficients S 0 , S 1 , . . . , S K/2-1 where K is an even integer which factors as K=MQ with M and Q integers; (b) effecting a matrix multiplication V i =Î£ 0â‰¦kâ‰¦K/2âˆ’1 N i,k S k , for i=0, 1, . . . , Kâˆ’1, where the matrix elements are N i,k =cos[(i+z)(2k+1)Ï€/K] with z an integer multiple of Q; and (c) wherein said matrix multiplication implementation includes: (i) for an mth subblock of said block where m=0, 1, . . . , Mâˆ’1, applying a cosine transform to give outputs Gc(q,m) with q=0, 1, . . . , Qâˆ’1; (ii) for said mth subblock, applying a sine transform to give outputs Gs(q,m) with q=0, 1, . . . , Qâˆ’1; (iii) applying a cosine transform with respect to the index m to a linear combination of said Gc(q,m) and Gs(q,m) with coefficients cos[(q+z)(2m+1)Ï€/K] and âˆ’sin[(q+z)(2m+1)Ï€/K]; and (iv) applying a sine transform with respect to the index m to a linear combination of said Gc(q,m) and Gs(q,m) with coefficients âˆ’sin[(q+z)(2m+1)Ï€/K] and âˆ’cos[(q+z)(2m+1)Ï€/K].