基于H.264标准的码率控制改进算法

An improved rate control scheme based on H.264 video coding standard

本文利用视频编码的线性码率控制(RC)算法(Rho-Domain算法)对原有的H.264标准中的RC算法进行了改进。首先,对于视频序列中的I帧图像,使用Rho-domain算法进行码率控制。由于该算法基于本帧的图像内容,所以能够及时地对I帧进行精确的码率调整;其次,使用了新的关于P帧的比特分配原则,根据GOP中的位置来分配P帧的比特数;最后,对模型的估算方法作了改进,使模型参数的计算更为精确。实验结果表明,改进后的算法能更加有效准确的控制编码序列的码率。

This paper proposes a new scheme about the rate control （RC） in H.264 coding standard. By transferring the Rho-Domain RC algorithm to I-frame RC, we can control the I-frame bits depending on the its image content. Thus, the problem of frame skipping is alleviated. Furthermore, with considering about the different importance of each P-frame in a group of picture （GOP）, we modify the bit-allocation rule of P-frame. In the new rule, the allocated bits for one P-frame will not be a simple constant average but a function with respect to the P-frame position in the GOP. Finally, we introduce an improved algorithm to estimate the parameters of mean absolute difference （MAD） model and RC model with respect to the different contribution of all inliers. Experimental results show that the new rate-control scheme can control the I-frame bits very well and significantly reduce the occurrence of frame skipping. The parameters of models can also be estimated more accurately.