The Design And Realization Of Synchronous Multimedia Resource On-demand System Based On SMIL

Multimedia on demand (MOD) system is important applicationsystem of distributed multimedia. The MOD is a technique leadingthe edge of current multimedia communication application, whichcombines with the information falling the future and communicationrelated. It can realize the teaching content, video and audiosynchronous broadcast which satisfy the demand of the networkassistant education.The RTSP is build on the transmission protocol of stream media,which doesn't send out continuous stream, but acts as remotecontrol of multimedia server. The key demand for transmissionprotocol is that whether the protocol can deliver the real-time datain time or not, whether the reception fraction can press it in orderaccording to data sorting and playback it from the timestamp of data.RTP/RTCP is protocol based on the real-time continuous multimediaof the session layer. The RTP/RTCP provides the identification ofthe type of load, the code of order, and measure of throwsindiscreetly;the transmission monitoring etc., the applicationprogram available can resolve the unpredictable delay and jitter inthe transmission process.The multimedia synchronization has been more and moreattention as the crisis question in multimedia communication. To bethe integrate of various data, its synchronization is to maintains thetime sequencing of one or several media streams, which includessynchronization inside and outside of the media. The research on themultimedia synchronization mainly on two aspects, the method ofdescription and the carrying out. In recent years, there is greatprogress on the research of description of multimediasynchronization, the research on the realizing mediasynchronization, mainly on the opened distribution heterogeneityplatform. In a word, the design of the multimedia synchronousscheme should satisfy many communication pattern, selection vividmethod of synchronous, making it arithmetic simple and smalleradditional system paying.The SMIL is a marked language similar to HTML, which candescribe the real-time behavior, the screen present to public andcooperate with the hyperlink of the medias can play to show of thestream video, audio, image, text etc. It allowed the independentlymultimedia object in a multimedia show of synchronization, andconvenient to synchronous several objects based on stream by SMILlanguage. The product and international standard language providedan emollient guarantee for the multimedia extend environmentaccording to the stream, and suitable to the Internet. Currently,SMIL support almost al the multimedia information styles, such asthe AVI, WAV, MOV, RA, RV, RM, MIDI, AU, AIF, ASF, and theshockwave flash etc. The importance and distribution of mediaresource can be greatly raised by using the URL to gather the mediaresource to the SMIL document.The fulfillment of using the SMIL language to integrate mediainformation can prove that, the association of SMIL synchronouswith multimedia network technique, solve the problem that the lackto unifying in traditional Internet multimedia resource, and thedifficulty of carrying out synchronous model and synchronousmachining, the body appears simple and direct, open, and the strongalternation provide a practical and viable multimedia environmentfor the net extend education, and make it to the effect that realizingreal-time reversible transmission to show synchronously. Theimplementation of MOD based on the SMIL can effectively integratethe teach resource, provide kind environment of on-line studying,put the teaching of the real-time and the teaching of the non-realtime together to improve the efficiency of the students' study.The article takes the design of the build and the operation of thenetwork-aided instruction system as background, carried outsynchronous media resource on-demand (SMOD) system based onSMIL. The realizing SMOD system emphasize on thesynchronization of stream by using SMIL language and set up ofSMOD system. In the process of integration media document usingSMIL, because of numerous quantity of the media document, thework is heavy and easily made a mistake by editing the SMIL loadby hand. In the research afterwards, the core research is on thetechniques of SMIL auto setup and manufacture by the usage ofscript techniques to set up the network instructional media.Meanwhile, give a more thorough research on the synchronousbetween media and the method of carrying it out.This article research on the related technique and the process ofrealizing system based on the SMOD of SMIL, mainly divided into afew fractions as follows.Firstly, there are research on the technique of stream mediatransmission and related transmission protocol. Mainly analyze thebasic principle of the stream media transmission, the format ofstream media file and broadcast mode, put forward with providingthe real-time stream transmission protocol as the server ofSMOD system. In order to use RTP/RTCP and RTSP to support thetransmission of the real-time stream media, in the stream mediastudies on the stream media transmission protocol RTP/RTCP, RTSPand RSVP is carried on the structure, workflow and data format.Study the message, state, protocol operation, and realizing structureof server and client based on the protocol. Explained the selectionof the real-time transmission protocol plays an important part tostream media transmission quality.Secondly, the multimedia synchronous in the SMOD system isresearched. It mainly includes the assorting of the synchronousmedia, QoS and the structure model of media communicationsynchronous. It points the typical description model, such asInterval-based model, Timeline model and reference point model etc.The article also gives an analysis to the realizing method ofmultimedia synchronization.Thirdly, the synchronous time model and stream mediaarchitecture based on SMIL are put forward, and the description ofthe characteristics and language criterion is done. The synchronoustime reference model of the SMIL language is analysis and there areexplicit explanation on its synchronous time dependence relationdiagram module and the certain time table module. AccordingSMOD architecture based on SMIL, the function of each module isresearched.The end, the model and the process of realizing of SMOD systemis introduced, and the performance analyze and testing of server iscarried on. The testing result observed that SMOD systemperformance achieved expectable destination. The testing resultshows SMOD system performance achieved expectable objective.