| 摘要 |
An MPEG decoder system and method an MPEG decoder system and method for decoding frames of a video sequence. The MPEG decoder includes IDCT computation logic which computes the IDCT with improved performance. The IDCT logic performs the inverse DCT based on the Chen algorithm for IDCT computation. The system and method of the present invention efficiently utilizes properties of the coefficients in optimizing the matrix multiply functions, thus providing improved performance. Chen's algorithm is commonly used to perform the two-dimensional IDCT. According to the Chen algorithm, the transform matrix I is defined as:[I]=[Q]x[P]The Chen algorithm calculation can be written as:f=(QxFTxQxP)TxPThe Q matrix is a diagonal matrix which has diagonal non-zero values, with the remainder of the values being 0. The P matrix includes a plurality of values which are the opposite sign of each other. The system and method uses the diagonal nature of the Q matrix, the similarities or symmetry in matrix coefficients in the P matrix, as well as the nature and bit representation of the P matrix coefficients, to perform more efficient IDCT computations.
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