The Research Of Multimedia Dynamic Synchronization Model Based On Timed Petri Net And Control Mechanism

Synchronization is the key technique and basis of the distributed multimedia system. The synchronization relationship exists during the life period. In this thesis,the complicated temporal relationship and dynamic synchronization properties existed in multimedia in distributed multimedia system,and the problem of higher priority demands of key medium in application,and etc. are studied thoroughly;The course of multimedia communication,the transmission characteristics and the synchronization requirements of multimedia objects,and the algorithms of channel allocation and synchronization transmission schedule in synchronization communication scheme,and etc. are studied deeply;At the same time,the problems of multimedia synchronization control mechanism in the practical packet-switching networks and so on are studied too. The main contributions of this thesis as follows:1. Starting from the time theory and the temporal logic,and taking into account the dynamic properties of multimedia performance,the extended uncertain interval relationships set adapting to describe the multimedia system is proposed. By deducing in theory,it is simplified to a very plain temporal model that has only 6 canonical operation symbols.2. The TPN model based on the extended temporal relationships set is described. Furthermore,it is proved that every synchronization relationship among multimedia objects can be denoted with the TPN model.3. An improved interactive dynamic multimedia synchronization model (IDSM) based on TPN is proposed. The new model takes the dynamic synchronization properties and the demands of the priority of key medium and the function of user interaction in the distributed systems into account,introduces the allowed blocking time,backtracking rules and so on to handle the problems caused by random delay,blocking or lost packets,and describes the temporal behavior of multimedia information stream fully,accurately and formally.4. A new optimized channel allocation scheme is proposed according to the model of IDSM,and a control model of synchronization communication (DSCM) is proposed based on the optimized channel allocation scheme,including server DSCM and client DSCM.5. A adaptive multimedia synchronization control mechanism based on the leak-bucket algorithm is proposed. It estimates the range of delay according to the practical network load by making use of the time-stamp of the medium units,and adjusts dynamically. It is effective in various networks,and can satisfy the QoS demands of multimedia synchronization.