DOWN-CONVERSION OF AN HDTV BITSTREAM TO AN SDTV SIGNAL
Wenwu Zhu, Kyeong Ho Yang, Farid A. Faryar · 1999
In the future of the digital television (DTV) broadcasting, a standard deflnition television (SDTV) de- coder should have the function of receiving a high deflni- tion television (HDTV) signal and display it on its mon- itor. In order to do so, it is required to convert an HDTV bitstream down to an SDTV signal. In this pa- per, we propose a fast and memory efflcient algorithm for the down-conversion. The proposed algorithm saves lots of computation of the down-conversion by combining inverse discrete cosine transform (IDCT) with the pixel-domain down-conversion. It also requires a smaller memory by performing motion compensation (MC) after the down- conversion, compared to the conventional scheme where MC is performed before the down-conversion. In the brute- force IDCT case, the computation savings of our proposed algorithm are 62%, 74% and 84% for down-sampling ra- tios of 2:1, 8:3, and 4:1, respectively, with the same pic- ture quality compared to the conventional memory emcient pixel-domain approach. In the case of using a fast IDCT algorithm, the computational savings are respectively 25%, 31% and 37% for down-sampling ratios of 2:1, 8:3, and 4:l.