由于H．264算法中宏块划分的灵活性导致了头信息的数据量变化剧烈而难以预测，同时由于变换系数的数据量大大的减小，又使头信息量在码流中所占的比重远高于在先前各个标准的码流中的比重，因此准确估计头信息量能有效提高H．264码率控制算法的性能。为了准确估计头信息，提出了一种应用卡尔曼滤波器估计帧级总头信息比特数的方法，并将该方法应用于帧级的码率控制。实验结果表明，该算法能准确估计头信息，并能在一定程度上提高相同码率下的总体图像质量。

H. 264/MPEG-4 AVC features flexible macroblock mode decision, which makes the number of data bits produced by encoding header information in H. 264 video stream vary irregularly and hard to be predicted. As H. 264 encoder reduces the data bits for transform coefficients effectively, the number of header bits takes a larger portion in the overall bits than that of any former video compression standard. Thus precise estimation of header bits can effectively improve the performance of the H. 264 rate control algorithm. In this paper, we apply the Kalman Filtering theory to improve the precision of estimating the number of the header bits at the frame layer, and incorporate the estimation model to frame layer rate control.