基于DCT的帧内视频编码器的缓存控制技术

A Buffer Control of DCTBased Intrafield Videl Coding

提出一种基于ＤＣＴ的帧内视频编码器的缓存控制技术。它根据视频图像各种子块的比例及其相应的Ｒ－Ｑ曲线确定量化因子，通过再编码，调整子块Ｒ－Ｑ曲线的拟合参数使其自适应视频图像的场景变化。同时本文提出了一个简单有效的图像子块分类方法，分类结果基本上与根据编码子块所需比特数分类子块的结果相一致。此法用于缓存控制的额外计算量小，并能扩展应用于Ｈ．２６１、ＭＰＥＧ等视频编码标准中。模拟结果表明，此法在视频序列的场景发生变化时，再编码次数少，输出码率恒定。

A new buffercontrol policy for DCTbased intrafield video coder is presented.It selects quantization parameter based on the number of three kinds of blocks in a picture and the ratequantization models(RQ model)for three kinds of blocks.It adapted to the scene changes through reencoding the picture and adjusting the RQ model.A simple and effective criterion is presented to classify the blocks,the classifying result based on it is close to the result gotten through quantizing the bits needed to code a block into three levels.This method can be applied to some other coding techniques such as H261;MPEG,extra computations are modest.Simulation results show that this buffer control policy can control the output bit rate steadily even at scene changes.