In this paper, we propose a new fast algorithm for block motion vector (MV) estimation based on the correlations of the MV's existing in spatially and temporally adjacent as well as hierarchically related blocks. We first establish a basic framework by introducing new algorithms based on spatial correlation and then spatio-temporal correlations before integrating them with a multiresolution scheme for the ultimate algorithm. The main idea is to effectively exploit the information obtained from the corresponding block at a coarser resolution level and spatiotemporal neighboring blocks at the same level in order to select a good set of initial MV candidates and then perform further local search to refine the MV result. We show with experimental results that, in comparison with the full search algorithm, the proposed algorithm achieves a speed-up factor ranging from 150 to 310 with only 2-7% mean square error (MSE) increase and a similar rate-distortion performance when applied to typical test video sequences.

Motion vector (MV) estimation plays an important role in motion compensated video coding. In this research, we first examine a stochastic MV model which enables us to exploit the strong correlation of MVs in both spatial and temporal domains in a given image sequence. Then, a new fast stochastic block matching algorithm (SBMA) is proposed. The basic idea is to select a set of good MV candidates and choose from them the one which satisfies a certain spatio-temporal correlation rule. The proposed algorithm reduces matching operations to about 2% of that of the full block matching algorithm (FBMA) with only 2% increase of the sum of absolute difference (SAD) in motion compensated residuals. The excellent performance of the new algorithm is supported by extensive experimental results.Keywords: motion vector estimation, spatio-temporal correlation, stochastic block matching algorithm 810 / SPIE Vol. 2501 0-8194-1858-7/95/$6.0O Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/25/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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In this paper, we study the robust transmission of video over wireless cellular channels. The source video is coded based on the H.263 standard for the low bit rate coding where the transmission rate is limited to 64 kb/s and below. Due to the nature of burst errors in fading channels, the video communication system needs to be robustly designed. Unnecessary overheads should be prevented because of the limited bandwidth of wireless channels. The techniques of automatic repeat request (ARQ) and forward error correction (FEC) are employed. It is shown that to obtain the same video quality, ARQ system requires less overhead than FEC. Our simulation gives the results in favor of using ARQ for error control rather than FEC at the bit error rate of under the channel environment stated in the IS-95 standard.

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