Research On Rate Control Method Of Video Coding Based On H.264

With the coming of IT era, the requirement of multimedia information is increasing. Voice and data communication can not meet people's need any more, so the requirement for businesses of digital video and image is increasing enormously. Video communications require more bandwidth, however, communication bandwidth is very limited. So, the effective bandwidth costs is especially important. And the most effective way to save the bandwidth is to compress video source largely. H.264 is a new generation video compression technology for low bit-rate visual communications, which was developed by Joint Video Team (JVT). JVT is made up of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC MPEG. It is also hot topic in the current research of image communications. Rate control is an important component of H.264. If there is no rate control any video coding can not be applied in practice. So for different standards and use, H.264 rate control which is one of the key technologies has became a hot topic in video compress research.Firstly, this paper give a study on key technology of H.264 and rate control which based on H.264 and the problems that it is faced with. Then after analyzing several important resolutions about rate control of H.264 which have been proposed by JVT, this paper discusses the classical method rate control and the method improvements of rate control based on H.264 .With the researching above, towards the shortcomings which the computation of target bits and quantization parameter in the situations of high motions and scene change in rate control of H.264,this paper proposes a method of frame-level target bits allocation which based on the frame complexity to improve the above-mentioned two aspects. The experimental results show that the improved algorithm can make target bits closer to the actual bits, increase peak signal to noise ratio, decrease fluctuation of peak signal to noise ratio.There are lots of methods to improve the rate control algorithm .This paper use the complexity of frame to re-allocate the quantization parameter to make the bits allocation more rational. For different applications, rate control algorithm can choose different improved strategy. so, the rate control model should also be combined with the practical application. The more use of the image characteristics is a potential direction.