A Fast and Memory Efficient Algorithm for Down-Conversion of an HDTV Bitstream to an SDTV Signal

In the future of the digital television (DTV) broadcasting, a standard definition television (SDTV) decoder should have the function of receiving a high definition television (HDTV) signal and display it on its monitor. In order to do so, it is required to convert down an HDTV bitstream to an SDTV signal. In this work, we propose a fast and memory efficient 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 case, the computation savings are 62%, 74% and 84% for down-sampling ration of 2:1, 3:1, and 4:1 respectively, compared to the conventional memory efficient pixel-domain approach, with the same picture quality. In case of using a fast IDCT algorithm, the computational savings are respectively 26%, 31% and 37% for down-sampling ratio of 2:1, 3:1 and 4:1.