Network Transport Simulation

Several functionalities are added to the codec to make it simulates the operation over packet network by TEMICS team at the IRISA. The encoder generates marks in the output bit streams to indicate the start and end of each packet. In addition, the encoder provides some ways to cope with packet loss effects (error resiliency) [84]. The ability of inserting a header at the beginning of each group of blocks (slice) is allowed to deal with the spatial encoding problem due to loss. In addition, it is possible to force Intra mode coding of macro-blocks in certain way to avoid the problem of loss due to the temporal encoding. The maximum packet size can be varied to suit the requirements of network supporting the transmission. The default size is set to 536 bytes to avoid the fragmentation of packets between routers if the transmission is over the Internet. The packetization process is made to be with conformance with IETF RFC 2429 [69]. The program can also generate packet loss patterns by Gilbert model. Another models of packet loss can be defined. In addition, the decoder has another way to deal with loss distribution by giving it the sequence numbers of packets to be dropped. We further modified the simulator to suite our need to generate the video sequences, to carry out subjective quality tests and to implement the video application.