A Fast Arbitrary-Ratio Downscaling Algorithm for Video Transcoding

W. Wen, Y. Liu, and H. Hu (PRC)


Video transcoding, downscaling, DCT domain


This paper presents an algorithm for arbitrary-ratio video downscaling in the compression domain. The existing video downscaling algorithms are special cases with respect to our algorithm. In addition, these algorithms are computationally complex for fractional ratio downscaling and are only suitable to integer ratio downscaling in some cases. A striking characteristic of our proposed approach is that it can perform downscaling for arbitrary factors with relatively few calculations. The proposed algorithm comprehensively uses the shift-matrix and discrete cosine transform (DCT)-base transformation matrix and employs a lookup-table to speedup the matrix multiplication. Experimental results show that the proposed method can achieve a fast computation speed and has high PSNR compared with the traditional methods.

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