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运动搜索一直是混合视频编码方案中最占编码时间的模块。典型的运动搜索由整像素搜索和半像素搜索组成。随着整像素搜索算法的不断改进 ,被普遍使用的半像素全搜索方法在整个运动搜索中所占运算量已经不容忽视。为了加速半像素搜索 ,提出了一种基于抛物面预测的半像素快速搜索算法。实验结果表明该算法能显著地提高半像素搜索速度 ,并且不会对编码效率和图像质量产生明显的影响。在QCIF格式下采用 H.2 6 3编码器时实际节省运算量约为5 7%。该算法的预测过程简单 ,易于实现 ,能够方便地集成到现有的编码系统中
Motion search has been the most dominant component of mixed video coding schemes for coding time. A typical motion search consists of an integer pixel search and a half-pixel search. With the continuous improvement of the whole pixel search algorithm, the commonly used half-pixel full search algorithm can not be neglected in the entire motion search. In order to speed up half-pixel search, a semi-pixel fast search algorithm based on parabolic prediction is proposed. The experimental results show that the algorithm can significantly improve the half-pixel search speed, and will not have a significant impact on the encoding efficiency and image quality. In the QCIF format using H.263 encoder actually save about 57% of the amount of computation. The algorithm has simple prediction process, easy to implement and can be easily integrated into the existing coding system