视频传输中的码率控制技术

码率控制是视频通信系统中的一个天键环节，主要用于调摔编码视频的输出质量。设计码率摔制系统时一般需要涉及目标码率计算、信源与信道模型建立、视频编码方法、率失真估计、码率分配、跳帧、实时性、传输环境和系统性能评估等诸多方面。新出现的网络视频流媒体传输、无线信道传输、MPEG-4的对象编码传输、信噪比精细可分级编码传输等实际应用要求鲁棒高效的码率控制算法来满足视频实时传输的需要。相应的码率摔制算法已成为近几年的研究热点。本文给出了视频码率控制技术的系统框架和基本要求，介绍了现有的各种恒定码率(CBR)与可变码率(VBR)摔制算法，综合比较了各自的优缺点，概括论述了视频码率控制技术的发展现状，并给出了下一步的研究方向。

Rate control techniques for video transmission

The primary goal of rate control is to regulate coded video quality. The design of a rate control system requires careful attention to the following issues: target rate calculation, source and channel modeling, video coding, rate-distortion estimation, bit allocation, frame skipping, real-time implementation, transmission environment and performance evaluation. New and emerging applications, such as Internet video streaming, wireless channel transmission, MPEG-4 VO (Video Object) coding and SNR FGS (Fine-Granular Scalability) coding, require robust and efficient rate control techniques. More recently rate control techniques and methods in those areas have been receiving increasing attention. This paper presents the general framework and fundamental demands for a rate control system, introduces various existing algorithms for CBR (Constant Bit Rate) and VBR (Variable Bit Rate) video, summarizes and compares some of well-known methods. The paper also introduces current research activities and proposes several research topics at the forefront of this challenging field.