| 摘要 |
After a windowing operation h(n) performed by space-time weighting of the samples, a method and an apparatus for encoding-decoding a digital signal comprising a sequence of samples x(n) consists in performing a modified discrete cosine transform of the samples to calculate the even order transformation coefficients: <IMAGE> +TR (4 + 1) x pi /4 for k epsilon [0, . . . , N/2-1] with YN-k=-Yk-1 The coefficient Y2k are expressed in the form of an invertible complex transformation: Y2k + N/4 + jY2k = (-1)k+1 x W8-1 x <IMAGE> +TR W4N(4k+1)(4n+1) for k=0, . . . , N/4-1 with y'n=x2n.h2n y''n xN-2n-1.hN-2N-1 W4N=cos(2 pi /4N)+j.sin(2 pi /4N) The invertible comples transformation is calculated using an auxiliary calculation equation: <IMAGE> with: zn=(y2n-yN/2-1-2n)+j(yN-1-2n+yN/2+2n) The invention is applicable to encoding and decoding digital audio or video signals.
|
