The Research Of Variable Bit-Rate Wireless Video Transmission System Based On H.264

With the fast development of wireless communication and video compression technique, wireless video communication is widely used in many fields. In the realm of industry, it can be used in video monitor and remote data collection systems. In the realm of medicine and health, it can provide the remote support of medical treatment. In our daily life, digital TV service, video conference system and many video calling applications are all based on the technique of video compression and internet transmission.This paper mainly deals with problems encountered in the process of wireless video communication and introduces some key techniques related to these Problems. We use the H.264 as our standard of video compression, which is the newest, efficient and more compatible for the internet. The open source code library X264 is adopted to code the video sequence. We use the RTP/RTCP as the network transport protocol. RTP deals with the real-time transmission of the video sequence while the RTCP is responsible for analyzing the current state of the network and sending the information such as packet loss rate, time delay and network jitter, etc back to the sender. Thus, the sender can control the network congestion based on this information. This paper achieves the process of wireless video transmission and the control of sending rate based on the feedback of RTCP, in order to control the bit rate.This paper first introduces some techniques related to wireless video transmission including video capture technique, etc. Than puts emphasize on some new techniques emerged in H.264 as well as X264. Further study is made in bit-rate control algorithm and improvement in ABR algorithm of X264 by adding the factor. The results show that, after the improvement, the bit rate is closer to the target bit rate and also the coding speed is increased. There is a slight decrease in S/N ratio, but the PSNR-MSE is decreased. Moreover, in order to solve the problem that the coding library can not change the target encoding bit rate, this paper proposes an algorithm that can change the bit rate based on the situation of internet, which is more compatible for the condition of wireless video transmission.