低延时无线视频传输中的H.264码率控制算法

针对基于ARQ机制下的低延时无线视频传输,提出了一种有效的信道信源联合码率控制方案。该方案首先利用Markov模型作为无线信道模型来预测估计信道的状态和带宽,并以基于Cauchy分布的率失真模型作为信源模型;然后在帧层设计了一种基于PID控制器的缓存控制算法,即根据预测信道带宽和缓存器状态来分配每帧目标比特数,以提高缓存的控制能力;对于宏块层则在监控缓存器状态的同时,利用基于Cauchy分布的率失真模型,最后通过Lagrange方法来优化分配目标比特数。实验结果证明,该算法不仅能显著提高平均峰值信噪比,并能大幅减少跳帧数目。

A Rate Control Algorithm for H.264 Low-delay Video Transmission over Wireless Network

In this paper,we proposed an efficient joint source-channel rate control algorithm for real-time wireless video transmission which use automatic repeat request scheme to retransmission the error packet.The two-state Markov model was used to simulate the wireless channel,and the Cauchy-distribution-based rate and distortion model were used as the source model.In the new scheme,at frame level,a PID-controller-based buffer control algorithm was developed to improve the buffer control ability which allocated frame target bit based on the channel bandwidth and buffer status;at macroblock level,the frame bit-budget was distributed among macroblocks using the new rate-distortion model and Lagrange optimization method.Experimental results show that,the proposed algorithm can improve the average PSNR and decrease the number of skipped frames significantly.