Based On H.264 Transcoding And Rate Control Techniques

With the development of the times, multimedia technology has been widely applied, digital video compression technology has also been extensively studied. For the people's needs, transmission networks and receiving equipment are different, it is necessary that the compressed video data is converted when it is transmitted, and this process of conversion is called video transcoding. Rate control strategy is one of the key video coding techniques, and it has an important impact to image quality and bit rate.This paper has two main contents for research. One is about the video transcoding algorithm for compressed video data between AVS(Audio Video Standard) and H.264,and we ultimately proposed a kind of video transcoding Fast Algorithm for AVS to H.264 which completes the transcoding from AVS to H.264. The other is about rate control technique of H.264.Based on the study for the principle of rate control and classical rate control algorithm and detailed analysis of G012 algorithm, we present several methods for improvement of G012 algorithm of H.264 and show the effectiveness of improved algorithm through the simulation results. First, Taking into account the influence of bit rate that the last Group of pictures (Group of Pictures, GOP) caused, we changed the algorithm about how to calculate the Initial QP. Second, in the frame-layer rate control algorithm, we use the complexity of frame to address allocation problem in the P-frame bit rate. Finally, macro block layer control strategy is introduced for the G0 12 algorithm, taking into account the correlation between macro blocks and the macro block complexity, we calculate QP for each macro block in the basic unit, so the accuracy of rate control and the quality of image can be enhanced. Simulation results show that research content and algorithms are correct and feasible.