A H.264 Rate Control Algorithm And Its Application In The Scene Change And Research

The H.264 video coding standard is established and released by JVT in 2003. Compared with previous standards, H.264 has higher compression efficiency and better network adaptability. It promotes the applications of video technology on the broadcast network, on the television network, on Internet and on the wireless communication network. Coupled with the widespread use of the standard, some defects are gradually exposed. So, the JVT meeting absorbs the recommendations and views from researchers around the world, and constantly improved the H.264 standard to enable them to apply varieties of occasions better.As initial quantization parameter computed algorithm in the H.264 rate control is too simple and the scene change happened in videos is not considered, some improvement points are proposed in this dissertation. The main content is an follows:(1) The basic principles of rate control in video coding is described. According to the simulation on the H.264 reference software JM13.1, the affects to the video quality and the bite rate aroused by the quantization parameters and the length of group of picture are presented objectively.(2) The three-layer rate control algorithm is deeply studied. Since the quantization parameter computed method of the initial P frame is not enough accurate, this thesis digs out the relationship between the original I frame and the initial P frame, and improves the quantization parameter computed method of the initial P frame. At the same time, the improved algorithm is implemented on JM13.1. The simulation results show that compared with the existing initial quantization parameter algorithm, the new algorithm advanced by this thesis amends the video quality and doesn't increase the excess bite streams.(3) As we all know, the rate control algorithm of the H.264 standard and the previous video coding standard, the situation of scene change is not considered. So, this paper analyzes the impact of scene changing to the video quality and the bit rate, and combined with the new initial quantization parameter algorithm this paper brings a new rate control algorithm applied to scene change forward. In the end, the simulation results reveals that the new algorithm improves video quality significantly, while the output bite stream is also stable.