Based On H. 264 Video Motion Estimation Search Algorithm Research

With the rapid development of multimedia technology in recent years, the H.264video coding standard has become a hot research field in the video codec. The coding standard has adopt a lot of practical coding key technologies, including the prediction of inter or intra, motion estimation, block transform, quantization, entropy coding and filtering etc. These key technologies makes the video coding efficiency has been an unprecedented increase. However, the time of motion estimation occupied can be up to about60%in the entire coding system. and the motion estimation algorithm is more and more important in the entire coding system, and its performance can affect the efficiency of the entire coding system directly. So this paper did a profound study for the motion estimation algorithm. At present, many scholars have proposed some fast motion estimation algorithm. Including the Full Search algorithm, Three Step Search algorithm, Dlock-Dased Gradient Search algorithm, Four Step Search algorithm, Diamond Search algorithm, Cross Diamond Search algorithm and Hexagon Search algorithm and so on. However, these algorithms are easy to fall into local optimum in varying degrees.This paper describes the key technologies of the H.264video codec and the video standards briefly in the first, and then analyses the basic principles of motion estimation, the work principles of block matching motion estimation search algorithm and the evaluation method of block matching motion estimation search algorithm. This paper also has a profound study for the motion estimation of seven classic fast motion estimation search algorithm and focuses on analysis of the search strategy and search steps of these fast motion estimation and summarizes the drawbacks and occasions of these algorithms.The innovation of this paper is that proposed a new adaptive small diamond-hexagonal search algorithm to improve search efficiency based on the drawbacks of the diamond search algorithm and the hexagon search algorithm according to the law of motion of the real world video images. In this algorithm, it adopt the value of MAD of the initial search compared with the pre-set threshold to determine the activity of the current block movement. When the current block in vigorous motion, the algorithm selects the Hexagon Search algorithm; When the current block in slow motion, the algorithm selects a Small Diamond Search algorithm.This paper realized the simulation of an Adaptive Hexagon and Small Diamond Search in the H.264reference software model JM13.2, VC6.0platform. And compared by test results on several different types of motion sequence. The experimental results show that the algorithm saved the search time in motion estimation compared to other adaptive and use one of the two algorithm. However, the improved algorithm has no any effect on rate-distortion performance at the same time. So the algorithm has a good performance.