丢包环境中H.264视频编码的快速模式判决  

Fast-mode decision for H.264 video coding in a packet-loss environment

作　　者：兰梦[1] 张远[1] 魏雨农 

机构地区：[1]中国传媒大学信息工程学院,北京100024

出　　处：《中国图象图形学报》2014年第12期1759-1765,共7页Journal of Image and Graphics

基　　金：国家自然科学基金项目(61001177;61472389)

摘　　要：目的视频编码中传统的快速模式判决算法通常基于对视频源特性的分析,但如果考虑到信道传输中的差错,编码模式的率失真特性就会随之改变,快速模式判决算法的性能也会随之下降,需要考虑丢包环境对快速模式判决算法进行优化。方法为了解决这一问题,首先分析了丢包环境下各种编码模式的端到端率失真特性,在此基础上提出了一个分层结构的快速模式判决算法。通过快速估计出丢包环境下skip和intra模式的编码率失真代价,进而将模式判决的路径划分为non-intra和non-skip。结果将本文算法与基于遍历算法的容错视频编码算法进行对比实验,本文算法平均可以降低50%左右的编码时间,同时几乎不会降低率失真性能。结论实验结果表明,在对丢包环境下端到端率失真代价进行估计的基础上,所提出的分层结构快速模式判决的算法,可以在保证解码端图像质量的同时,显著节省编码时间,满足实时视频通信中对低复杂度和鲁棒性的要求。Objective Traditional fast-mode decision schemes are commonly designed on the basis of feature analysis of the source videos. However, the rate-distortion behavior of the coding modes changes when channel errors are involved. In this study, we propose a fast-mode decision scheme for H. 264 video coding to address the requirements of low complexity and error resilience in real-time video communications. Method We examine the end-to-end rate-distortion （R-D） behavior of various coding modes and derive a hierarchical mode decision scheme. We propose a fast estimation of the coding costs of skip and intra modes in a packet-loss environment and narrow the mode decision into a non-intra or non-skip path. Result The proposed algorithm is implemented in H. 264 reference software JM12. The classical error-resilient video coding algo- rithm that conducts an exhaustive search of all coding modes is used as reference. By efficiently skipping a number of mo- tion estimations and intra prediction mode decisions, the algorithm saves time by approximately 50% without deterioration in R-D performance. Conclusion Experiment results show that the proposed fast-mode decision algorithm based on the esti- mation of end-to-end R-D cost can achieve significant time saving and retain a good image quality.

关 键 词：视频编码 H.264 差错恢复 快速模式判决 

分 类 号：TP919.8[自动化与计算机技术]