Research On Multimedia Net-classroom Software System Based On Local Network

Nowadays, Computer Network Multimedia Technology is one rising application area which is developing rapidly; it contains multimedia information compressing technology, computer communication technology, data storage technology, and so on. Today, computer network multimedia technology has been used in many fields, such as: video internet meeting, cooperating work, computer assisted instruction, e-business, and so on. With the rapid development of Internet, it improves computer network multimedia technology, so it is possible for people to enjoy more multimedia informationand services.Multimedia Net-classroom Software System just made by computer network multimedia technology, it is a CAI (Computer Assisted Instruction) which based on CBE (Computer-based Education). Multimedia Network Classroom is a set of LAN based multimedia instruction management softwares. Usually it refers to on the foundation of commonness hall or teaching network, it uses software and necessary hardware accessory to realize teacher server and student client connection, and to realize screen, audio real time interactive around each computer, and it has multi-assistance teaching management function.With the development of network technology and multimedia technology, a lot of function which originally demands hardware acceleration gradually use software to complete. This system adopts the latest compress algorithm and data transmission technology, so it breaks the hinder and cost limitation of the old Multimedia Net-classroom Software System. In this system, we put forward the new method of Multimedia Net-classroom Software System, which is based on network. The new method not only can realize all the functions that the old ones can do, but also can solve many problems in the old software systems, we know that the problems are high cost of making up the Multimedia Net-classroom Software System, long cycle, hardly safeguard and not easy to use.Multimedia Net-classroom Software System is the main function: Broadcasting teaching, teaching demonstration, surveillance, alone Round, black screen control, mouse, keyboard lock, electronic raised their hands, remote control counseling, Whiteboard, messaging, and so on.In reading a lot of reference materials, as well as in the current mainstream multimedia classroom system of the network on the basis of this system is divided into the following three modules:1. Communication Module is the entire multimedia network support part of the classroom, all the teaching and management activities must be completed to the aid of Internet communications, according to the different means of communication we will be more point-to-point and it is divided into two sub-modules IP Multicast.2. The teaching module is the main classroom multimedia network, the completion of the main tasks of real-time multimedia teaching, including screen broadcasting teaching, Whiteboard, message boards and other sub-modules.3. teaching management module is supplementary teaching modules, mainly for the students to complete the management and monitoring, including systems management and network monitoring two sub-modules.In this paper, the classroom multimedia network status and key technology research and analysis, focusing on classroom multimedia network reliability for data transmission and multimedia data (especially the image data) compression algorithm, and other technical done a detailed study and design. Use the following several key technologies:1. Multi- spots communication: The real-time multi-spotscorrespondence model realizes the multimedia network classroom key,its main function is completes to course content processing and thetransmission. The multi- spots correspondence realizes this modelessential technology.2. Data compression and code technology: The picture, the videofrequency, the audio frequency and so on the multimedia signaldigitization later the data quantity very will be big, in under thepresent correspondence environment and the equipment, the directtransmission obviously is not feasible. Thereupon 20 for many years,the people unceasingly study under the guarantee certain quality andthe compression ratio premise data compression and the codetechnology. May divide into two big kinds according to the method: Akind is not damages the compression and the code. Another kind hasdamages the compression and the code, it is the hot spot and the keydomain which the recent years studied, its method including theforecast, changed slow, the model, based on important, mixes the codebased on the content code as well as in the above foundation.3. Multi-thread technology: Each advancement possibly contains severallines regulations, they may simultaneously carry out in theadvancement address space code. In order to achieve this point, eachline regulation has a group of CPU register and the stack. In order tomove all these regulations, the operating system rotates the way toprovide the time piece to the line regulation, this gives the personone kind of pseudomorph, looks like these regulations all also tomove. When founds a Window advancement, its first line regulation iscalled the master line regulation, by the system automatic productionthen may by this master line regulation production extra lineregulation, these regulations be possible to produce the more linesregulation.In this paper I do analyses and research about multimedia network schoolroom actuality and critical technology, mainly study and design the technology of the data transfer reliability of multimedia network schoolroom and the compression algorithm of multimedia data (above all image data).This paper has two innovation points:1. Using adaptive hybrid ARQ to process lost packet problem in communication of IP Multicasting. The system can select different options to process the problem of losting packets based on currently network status.2. Using JPEG compress algorithm which can compress screen picture redundant data within frame and CRC algorithm that it can compress pixel redundant data between two frames to reduce data transfer quantity largely.By analyzing detailed, this system proceed detailed design and realize above Microsoft corporate visual studio.net 2003 platform, construct a teaching system satisfaction the teaching demand in LAN environment. After design, I did many testing work in different environment to demonstrate innovation points.