Scalable HDTV coding using overlapped motion-compensated wavelet and lapped orthogonal transforms

A multiresolution scalable coding scheme for HDTV using hierarchical overlapped block motion-compensated (OBMC) discrete wavelet transform and the Lapped Orthogonal Transform (DWT-LOT) is developed to increase the robustness of HDTV signal against transmission noise and to eliminate the "drift" artifacts. A data loss concealment scheme is required to provide graceful degradation, especially in HDTV broadcast and transmission environments. The effect of "drift" artifacts is one of the major problems in a classical scalable video coding such as frequency scalable coding where different resolutions do not have their own accurate motion information. Our research not only exploits the advantages of discrete wavelet transform and hierarchical OBMC to solve the "drift" problem, but also enhances MPEG scheme, which is applied for the lowest resolution, by replacing the DCT with the LOT, along with OBMC to significantly improve the data loss concealment and mitigate the degradation of picture quality due to transmission noise. Three resolutions at the constant bit rate (CBR) for applications to HDTV, conventional TV, and videophone, are aimed. Data loss concealment, for both intraframes and interframes, is illustrated, the elimination of "drift" artifacts is demonstrated, and the superiority of the enhanced MPEG scheme over the existing MPEG scheme is shown. Simulation results also show that good subjective and objective quality can be achieved for all the three resolutions.