低码率视频编码的优化方法

An Optimization Approach on Low Bite Rate Video Coding

采用的低码率视频编码方法是以全局运动补偿和局部运动补偿为核心的混合编码方法.主要针对MPEG-4中原有算法计算量大、复杂度高的特点进行了编码系统优化,将这一编码方法实用化.该优化方法是针对占编码系统70%计算量的全局运动估计进行的,采用了基于运动特征的运动估计方法和鲁棒的目标函数,并在优化方法中引入了三级金字塔的分层计算.从对比实验结果来看,优化方法对不同运动类别视频的编码都是有效的,系统编码速度提高了3倍以上.目前,这项优化方法已经被MPEG-4视频编码优化小组采用.

The coding method in low bit rate discussed in this paper is a hybrid encoding architecture, which combines global motion compensation and local motion compensation coding. In order to solve the complexity and large quantity of calculations of global motion compensation in this kind of hybrid encoder, the feature based global motion estimation and robust object function and three-level pyramid calculation are proposed to improve the performance of encoder system, especially in speed. This optimal global motion estimation technique enhances the performance of coding system substantially. Some comparison experiments are made in order to validate the effect of the proposed optimization method with different resolutions and sequences in different bit rates. The encoder system speeds up more than 3 times after optimization through comparisons. The proposed method proposed is an attractive technique, which has been accepted by MPEG-4 video encoder optimization group.