Motion vector coding based on predictor selection and boundary-matching estimation

In most of recent video coding standards based on block-based hybrid coding scheme, especially in the state-of-the-art H.264/AVC standard, motion vector information occupies a considerable portion of the whole compressed bitstream. Therefore, the efficient coding of motion vectors has become an essential objective to further reduce the bitrate. In this paper, we propose a novel motion vector coding method based on predictor selection and estimation. First, the optimal motion vector predictor (MVP) is chosen from a predefined predictor candidate set consisting of both spatial predictors and temporal predictors to minimize the number of bits used for encoding motion vector difference (MVD). Then, in order to avoid sending extra bits for informing the decoder which candidate is selected by the encoder, boundary-matching (BM) estimation is applied at the decoder side to find out the optimal predictor. The basic principle of BM estimation is to preserve the spatial continuity of boundaries between currently reconstructed block and its neighbors. Simulation results show that compared to the original H.264/AVC codec, the proposed scheme improves coding efficiency for various video sequences.