Study On Encoding And Transmission Techniques Of Mobile Stream Video

The development of the 3G makes the wireless network provide stream media services possible. As a result, related technology has also become hot spots of study. Wireless channel has some disadvantages, such as bandwidth limited, heterogeneity, time-varying. So in the process of mobile vidio communicating, the two imortant things to solution are as follows. The first is making efficient video data compression in order to take full advantage of the limited channel bandwidth; and the second is giving error control and protection for the streams of the compressed file to enhance the anti-error performance of mobile channel, to improve the quality of video communication. In this paper, video codec and wireless transmission point of view, the mobile video codec and transmission quality control were studied theoretically, and finally a software implementation was given.The main works of this paper are in follows.1. Firstly, to improve the low performance of selection algorithm in prediction coding due to the prediction patterns are so many, the prediction patterns selection was studied. For intra prediction encoding, a fast selection method was proposed which based on image edge information. For inter encoding, a fast selection method was proposed which based on image texture complexity. The two methods were all verified by simulation.2. Secondly, the QoS (Quality of Service) problem of video transmission was studied. A hierarchical point of view was proposed and the transport layer was emphasized studied. For the TCP friendly congestion control mechanism called DTFRC was studied, which actively adjusts sending rate based on TCP throughput model. The throughput formula of active TCP model was derived.3. At last, the codec and transimission software implementation was studied. In video codec, mobile video codec was implemented based on test original code JM and X264. A GUI was developed with the functions such as video codec, data analyzing and video playing. In video transmission, the program of information transmission based on JRTPLIB was writen from server and client respectively.