Based On The H.264 Standard Rate Control Research

ITU-T and ISO/IEC join to establish and release a new generation international video coding standard: H.264/AVC.It uses the Rate Distortion Model to control the bit rate, and to achieve the best efficiency of compression under the situation when the bit rate is restricted. H.264 standard only prescribes video coding bit stream syntax and the method of decoding but has no definition about rate control. It provides more wider space for searching. In this thesis, the rate control algorithm is been investigated.Firstly, we introduce the development of the video coding standard, and discuss the key technique of H.264, including system composition, inter-prediction, intra-Prediction, integer transform, entropy coding, rate distortion optimization and so on.Secondly, the mechanism of the rate control and information coding model is described. The classical rate control algorithm in the video coding standard is analyzed, and with a deep research on the rate control algorithm in JVT-G012. Finally, Through analysis of the rate control in H.264, an improved rate control method is put forward. In this method, an improved frame complexity measure that uses a combination of MAD-based measure and PSNR-based measure is applied in the basic unit layer rate control. so that more accurate target bits allocation is achieved.With the computational complexity of the linear model for MAD prediction taken into consideration and using the space and temporal correlation among the sequences, an algorithm named the weighted model is presented to predict the MADs of the basic unit, which avoids the process of updating the parameters and reduces the computational complexity. Research results show that these improvements can commendably solve the problem that MAD can not accurately reflect picture complexity. the precision of the weighed model depresses coding complexity commendably, and has a good coding efficiency.