We describe a very low bit rate video coding framework in which motion correlation between successive video frames is exploited in the multiwavelet transform domain. Some complicated techniques, such as spatial prediction in intra coding, adaptive block size motion estimation, more than one previous frames for prediction in inter frames, and content adaptive binary arithmetic coding (CABAC) are used in H.26L standard. The testing results show that H.26L can greatly outperform MPEG-4 ASP in both PSNR and visual quality. However, the encoding of H.26L costs too much time for it is complex to use fast motion search in adaptive block size motion estimation, and CABAC needs much time to generate the code list for entropy coding. Whereas, only four types of symbol are generated after zero tree wavelet coding so that the entropy coding can cost less time than CABAC. Moreover, if we select 8× 8 sized block as a basic mode, which can be united into the large size mode if neighbored 8× 8 sized blocks have same reference frame and motion vector, then the fast motion estimation can be feasible. Accordingly, a fast motion search algorithm, multiwavelet transform, and a novel adaptive quantization schemer are applied to the proposed coding frame. Experimental results reveal 0.2–0.5 dB increase in coded PSNR at low bit rates over the state-of-the-art H.26L recommendation, and similar improvements over MPEG-4 at high bit rates, with a considerable improvement in subjective reconstruction quality, while simultaneously supporting a scalable representation.
Keywords motion estimation - video compression - scalar quantization - wavelet transform coding
Jiazhong Chen was born in 1970. He received the M.S. degree in computation mathematics in 1999 and Ph.D. degree in computer system architecture in 2003 from HUST. He is now a lecturer at School of Computer science and technology of HUST. His main research interests include signal processing and wavelet analysis, image and video coding.Jingli Zhou was born in 1946. She received the B.E. degree in 1969. She is a Professor and doctor advisor at university of science and technology. She had been a visiting scholar in USA from 1995 to 1996 and has been honor of the State Department Special Allowance since 1999. Her main field of research: computer network and multimedia signal processing.
Shengsheng Yu was born in 1944. Received the B.E. degree in 1967. He is a Professor and doctor advisor at university of science and technology. He had been a visiting scholar in west Germany from 1982 to 1983. His main field of research: computer network and storage, discrete signal processing and communication.
Jun Xu was born in 1981. He received the B.S. degree from HUST, Wuhan, P. R. China, in 2003. He is now pursuing his M.S. degree in the School of Computer Science and Technology of HUST. His research interests are wavelet analysis, image compression and video processing and communications.