Research On Multimedia Playback Control Based On Network Calculus

The rapid development of Computer networks and communications technologies has greatly promoted the development of multimedia communication technologies. Compared with traditional data applications, multimedia applications have integrated kinds of different natured media, especially the new services emerged in recent years, such as IP telephony, VOD (Video On Demand), network conferencing, distance education and so on. These real-time services need higher QoS (Quality of Service) , namely reliable transmission network, strict end-to-end delay and jitter, and so on. Effective mechanisms to play media to the user with a synchronous way is needed. Among them, playback control is a basic strategy to ensure continuous playback of multimedia which is the important step.In the multimedia playback control, the problems such as how to design compensation buffer size and how to determine the playback point need to be considered carefully. In recent years, network calculus gradually becomes a real-time performance analysis tool for network communication, while the research on the Web-based multimedia playback control algorithms has just started, which will certainly become a hot spot in future research. On the other hand, extensive study results show that the network traffic has universal characteristics of self-similarity and long-range dependence. The basic assumptions of traditional queuing analysis model are Poisson distribution, which are no longer suitable for modern network traffic. Therefore, studying the principle of parameters setting under the self-similar multimedia playback becomes more important.In this thesis, we depthly study the playback control method based on network calculus and self-similar characteristics of network traffic and propose a new-playback control scheme by fully considering the self-similar characteristics of network traffic, which meets better the user's service quality requirements and makes the media player more smooth. The main research work and achievements of the thesis are as follows:1) Based on the analysis of multi-media playback control model, we study the playback method of calculating the control parameters based on network calculus, and make use of DirectShow to verify the correctiveness and effectiveness of the parameter settings.2) Based on the analysis the application protocol of real-time services, we proposed a feedback playback control method based on RTP / RTCP. The bandwidth is regulated and the resource is re-appointed according to the feedback imformation given by RTCP when the network state changes. At the same time, we derived the mapping relations between the effective bandwidth and buffer size with network calculus, and dynamically adjust the received buffer size so as to ensure smooth playing of video streaming.3) A synchronization control scheme is given based on monitoring the buffer size to adapt the broadcast rate. Based on the self-similar characteristics of multimedia network traffic, we use Frational Brownian Motion(FBM) queuing model to calculate the threshold of the buffer size. Finally, the reasonableness and correctiveness of the parameters seting scheme are verify through MATLAB and OPNET.