准确地估算信道失真是视频通信系统中联合功率率失真（P-R-D）优化的重要基础，提出了一种基于MPEG-4视频编码流的信道失真模型，采用帧间递归，根据信道平均误比特率和视频编码信息在编码器端实时估算视频序列的信道失真，仿真结果表明，对于不同的视频编码序列，在不同信道误比特率和信源编码率下，模型估算的平均相对偏差和绝对偏差较小，准确度高，为基于P-R-D优化的失真估算提供一个有力的工具。

Accurately estimating the channel distortion for the video communication is significant to the joint power and rate-distortion (P-R-D)optimization. This paper proposes a channel distortion estimation model based on MPEG-4 coding stream. The model recursively estimates the channel distortion of the video coding sequences according to the bit error rate of the channel and the video coding information obtained in the video encoder. Simulation results demonstrate that the average relative estimation error and the average absolute estimation error introduced by the model are small. The model is applicable for the relative optimizations based on P-R-D.