Lost motion vector recovery for digital video communication

Abstract

For MPEG-II and other hybrid MC/DPCM/DCT based video coding standards, it is very important to reconstruct the predicted frames based on the block motion information. In case of transmission over unreliable channels, error concealment methods are introduced to recover the lost or erroneous motion vectors. In this paper, a novel side motion estimation method is proposed to recover the lost motion vectors by selecting from a candidate motion vector set. The outer boundary of the lost block is used to perform motion estimation and the recovered motion vector is the one that minimizes the squared error of the block boundary pixels between two consecutive frames. The method takes advantage of the same motion direction of most blocks and their boundaries. It releases the boundary pixel gray level continuity assumption of traditional boundary match/side match approaches so that better estimation result can be achieved. Overlapped block motion compensation is also incorporated in the proposed method to reduce the blocking artifacts. By reducing the number of motion vectors in the candidate set, the performance of the proposed algorithm can be further improved.