Research On Adaptive Unequal Error Protection And Reliable Transmission Of Video Data

21 centry will be the information era and the main theme of this epoch is going to be multimedia communications. Being one of the most important types of multimedia services, video transmission in wired and wireless environments becomes a challenging task calling for high compression as well as robustness of the transmission. In traditional video communication systems, source encoder and channel encoder are designed separately, but present research shows that its theoretic basis- Shannon separating principle- can not be achieved in real communication system, source coding and channel coding should be considered jointly which can be advantageous in practice. Channel coding and protection schemes are one of the most important branches in joint source and channel coding research area.Supported by the national high technology research and development program of China (863 Program)–Joint Source-Channel Coding (No: 2002AA119010), this thesis focuses on the unequal error protection and reliable transmision technologies of video data. A novel adaptive UEP scheme applied across packets is proposed which realizes the protection over wireless video at frame level. After scaling the coded video data, five possible schemes are suggested, the research work includes granularity of the channel coders, adaptive channel coding and unequal error protection schemes. By adaptively adjusting RS coding rate and allocating the whole bit rate for different important data, we finally pick up the best performing scheme. The scheme proposed enables the real time protection according to variable wireless channel characteristics after the H.264 video coding. Simulation results show that, as the bite-error rate and band-width of the wireless channel change, our approach endues the PSNR of the decoded video at the receiver with stability and robustness.After unequally protecting the scalable video data, further study is carried out on how to packetize the protected data and how to apply end-to-end video send-receive method to reduce the side impact of network congestion. First, the research on packet loss patern over the Internet is reviewed. After analyzing the conflict between the correct probability of the received packets and the utilization rate of the packet units, a novel end-to-end video send-receive method is proposed based on a rate control technology using different packet sizes. At the sender, the multimedia data are divided into small packets in order to prevent random packet division by routers. At the receiver, two round buffers are set to resemble the frame data. The scheme not only avoids overflow of the buffers and conflict of the received packet units, but also decreases the negative impact to video decoder caused by packet loss and packet disorder. Practice proves that the quality of the decoded video pictures at receiver is distinctly advanced.The above research achievements were applied in the interactive distance education system, such as "Teamswan EasyLearning multimedia real-time distance education system", which is successfully runing in HUST and some other schools.