Application Research Of RS Code Based On IPTV

Over packet switched networks, the noise disturbance, network congestion, etc.will all lead to packet loss and burst errors.In these cases, the quality of video reconstruction will degrade severely.The result is IPTV can not be carried on normally So the large-scale deployment and application of IPTV will be seriously hampered all over the word. In order to improve the quality of service (QoS), error control technology based on terminal becomes more and more popular because of without changing the network architecture. As one of error control technology, application layer forward error correct (AL-FEC) is acquiring an increamingly important position.AL-FEC technology is basically based on erasure codes. Pro-MPEG Code of Practice #3(CoP3),Raptor code and RS code are the three mainly commom codes used for AL-FEC to recover losted packats. In these thesis, after a brief research of CoP3 and Raptor code, the theory and method of RS code'encoding/decoding for packets has been deeply studied .Furthmore,code has also been implemented which processes data packets. At last, the FEC module library which is designed and completed in C/C++ language has been added to the NS2 The main work and achievements are as follows:1. Based on network abstract layer(NAL) of H.264 encode, expound three types of encapsulation of RTP packets .2. Analysed encode/decode principle of CoP3 and Raptor code;,tested its recover rate at different code blocks with C programme.3. Implemented the encode and decode programe of RS code for AL-FEC. Drew the conclution of recover rate of lost packets at five different loss rate and time consuming of encode/decode.block. The most important, a new filling method of code block was disinged originally and it can effectively reduce the redundancy caused by aligning data when filling the code block.4. Developed the component library of NS2 with C/C++ language programme; implemented the FEC module of this network simulation software.5. Simulated the performance of AL-FEC(RS code) in multicast environment by script language programme(Otcl),and some results are concluded.