码率控制技术对提高和平滑解码视频质量起着至关重要的作用。近年来各种视频编码标准和应用都对码率控制技术进行了大量的研究，如基于H.261和H.263的视频会议，基于MPEG 1和MPEG 2的媒体存储，以及最新的基于MPEG 4视频对象编码。首先对码率控制问题进行了基本描述，然后介绍了标准中的经典码率控制技术，接着将目前的码率控制技术归纳为3类：基于DCT视频编码器的码率控制技术、基于小波视频编码器的码率控制技术和精细粒度可分级视频编码的码率分配算法，并对这三类码率控制方法的发展进行了概括性阐述与比较性研究，讨论了各种算法的基本思想及其优缺点，最后对视频传输中的码率控制技术的未来发展趋势进行了展望。

Rate control scheme plays an important role in improving and smoothing the decoding video quality. Over the years, rate control techniques have been studied very intensively for various standards and applications, such as video conferencing with H.261 and H.263, storage media with MPEG1 and MPEG2, and the recent video object coding with MPEG4.This paper firstly described the basis of rate control problem. And secondly classic rate control technology in the standard was introduced. Thirdly we summed up the present techniques as three kinds: rate control technique based on DCT video coder, rate control technique based on wavelet video coder and rate allocation of Fine Granular Scalable video coding. Then we generally discussed and compared the three kinds of methods including the core idea and the advantages and disadvantages of every algorithm of each kind of techniques. Finally, the state of art and possible new directions of rate control were stated.