In this paper, we propose a two-stage error-concealment method for block-based compressed video which was transmitted in an error-prone environment. In the first stage, we obtain initial estimates of the missing blocks. If the motion vectors associated with the missing blocks are available, motion compensation is used to provide good estimates. Otherwise, a novel algorithm which preserves image continuity is used to estimate the blocks. In the second stage, a maximum a posteriori (MAP) estimator, which employs an adaptive Markov random field (MRF) as the image a priori model is used to improve the video reconstruction quality. The adaptive model enables the estimation to incorporate information embedded not only in the immediate neighborhood pixels but also in a wider neighborhood into the reconstruction procedure without increasing the order of the MRF model. The proposed concealment method achieves very good computation-performance tradeoffs, as demonstrated via experimental results.
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