Research And Improvement, Based On The H.264 Bit Rate Control

H.264/AVC is a next-generation video compression standard with advantage of high compression ratio, high image quality and strong error resilience which is researched and published by ITU-T/ISO. Rate control algorithm is an important technology which reasonable distributes bit rate to improve video coding quality; its main challenge is the balance between the bit rate and the image quality.This paper focuses mainly on the study of H.264/AVC rate control technology, researches and analysis the existing algorithm to optimize the algorithm. The main contributions are as follows:First, H.264/AVC system, basic principles, applications and key technologies are introduced in this paper.Then, after reviewed, the existing classical rate algorithms and analyzed the key technologies of each algorithm, the H.264/AVC rate control test model JVT-G012 has been introduced amply in this paper.Finally, there are two shortcomings of the classic H.264/AVC rate control algorithm, one is the ignorance of the image complexity in bit allocation, and the other is there is no effective response of the scene change in the video sequence. For the first shortcoming. we adjust the rate stream by the complexity of the image which is reflected by the zero quantitative distribution of the quantized coefficients after DCT transformation and quantification. For the second shortcoming, we develop an effective rate control algorithm including the scene change detection and rate adjustment of corresponding switching frames. In this new algorithm, the coding quality of the switching frames is improved.According to the experimental results with different test videos, it can be shown that we get better PSNR and the output bit rates are more close to the target bit rate in the improved algorithm.