| Motion estimation is one of the most important operations in video encoding to exploit temporal redundancies in sequences of images. It is commonly utilized in many international video coding standards. However, it is also the most computationally costly part of a video encoder. Especially in the H.264, because of some new features, such as the variable-block-size motion estimation, and high-precision motion vector, the motion estimation has seventy percent of the amount of the computation. Motion estimation becomes the bottleneck of the video compression, therefore, efficient motion estimation algorithm have received considerable attention.By studying the features of H.264/AVC and the existing rapid motion estimation algorithms, three new algorithms are proposed according to the two key technologies which include block matching and the mode decision. The three algorithms are described as follows:(1) Fast Motion Estimation Algorithm based on Multi-pattern Search for H.264/AVC. In this algorithm, it first determines the current block as a quasi-stationary, slow motion, or fast motion block. Then, according to the different motion types, different search patterns and strategies are wisely employed.(2) Fast Motion Estimation with Multi-directional Adaptation for H.264/AVC. In this algorithm, according to the different motion types, different search patterns and strategies are wisely employed. Moreover, horizontal cross search pattern, vertical cross search pattern, diagonal cross search pattern, and anti- diagonal cross search pattern are combined to multi-directional searching. (3) Fast Inter-Prediction Mode decision algorithm for H.264/AVC. In this algorithm, direct detection for 16×16 is proposed to reduce the inter mode decision complexity based on the temporal and spatial correlation and SAD threshold for early termination. Moreover, according to the statistical analysis and the correlative characteristics of the seven modes, effective criteria for mode excluding is also employed.Experimental results demonstrate that the proposed algorithms can speed up the encoding time with the similar performance compared to standard... |
