【 Weak current College 】 VOD technology principle---Power By 【 China power house network 】

VOD system technical principle
VOD is integrated technology, including multimedia data compression technology, multimedia, network transmission technology and multimedia database technology for details. 1. the multimedia data compression technology Multimedia core is not a multimedia display technology rather than media break data compression technology. Multimedia data compression technique of the main issues include: data compression ratio and compression/decompression speed and simple algorithm. After the compression/decompression and compression of the data is in front of the original data exactly the same as a standard, you can put the data compression algorithm for lossless compression (reversible compression) and distortion in the compresses (non-reversible compression). 　 Digital video in-General accompanied by audio signal, so a blind eye to the frequency of data compression method in particular attention. Main video compression standards have H.261, JPEG and MPEG etc. MPEG standard is a high compression ratio, will still be able to guarantee high quality picture compression algorithm that is most appropriate for video storage, VOD VOD and online the gate-lose. MPEG is not only a technical, it's to become the industry standard for a multimedia exhibition on the technology of the people, for VOD applications system of production and development would have an important role. Multimedia network technology as the right to use the network of multimedia performance meet user's requirements, must be from the multimedia network and multimedia network bandwidth control technology two pronged approach, improve network speed and bandwidth resources, management capability and can *. (1) multimedia network multimedia data transmission on the network environment offers demanding requirements, morality is the high-bandwidth, network delay, particularly sensitive, multimedia network must use the appropriate control mechanisms and techniques, to ensure that network latency can satisfy the system requirements. User network environments including ATM network, ATM/Ethernet hybrid networks, Ethernet network, VOD applications mainly in the local area network. ATM and traditional hair too network differs in that it is connection-oriented protocol, because even switched Ethernet solutions, such as essentially still is not connected. ATM color connection-oriented technology that supports a variety of business, at the ATM of the resource reservation protocol RSVP video transmission provides QoS service quality food stores, making it more suitable than Ethernet transmission and application of multimedia. But ATM high investment collectors many users. Now most users already have a certain amount of TCP/IP-based network of environment issued too, if in a pure Ethernet or ATM/Ethernet hybrid online are able to carry out economic multimedia data transmission, video QoS-lose the user from Ethernet environment to best way AATM transition. (2) multimedia network bandwidth control technology multimedia network protocol is different from the ISO open systems interconnection reference model (OSIRM). Open Systems Interconnection reference model is a tiered model, emphasizes the organized transfer of data over the network, the computer provides an organized by logical communications legislation, can guarantee Wei output data independent of the system platform. And multimedia network card agreement you OSIRM based on the books to accommodate multimedia data, access, and Internet transmission. Standards is targeted at a single media OSIRM data transfer and sharing of network, did not provide multiple connection management, multiple live transmission and multimedia information synchronization and other multimedia network must function. Should therefore be extended to OSIRM, its underlying (physical layer and data link layer, network layer, transport layer) to improve the main consideration should be given to multimedia data bandwidth requirements, including the available bandwidth and bandwidth allocation. Available bandwidth determine network data transfer speed, bandwidth allocation decisions users to share the network information. On the main underlying extended OSIRM is reasonably dynamic allocation of network bandwidth, and adapt to multimedia data transmission speed and sudden. Multimedia database technology due to the sheer volume of multimedia data, along with the application of the scale, the system will accumulate large amounts of multimedia data, VOD data inventory management system must ensure that users can quickly and easily locate the desired material, effectively completed footage of various administrative tasks. VOD system in structural design has a direct impact on case performance optimization must be color, digital library technology structure is typical of optimization architecture. The rationale is Yin media storage and system management, retrieval, and other information processing part is logically separated from implementation to provide a clear logical merit first is an easy-to-user understanding, operation and use; second, the global system design, planning and implementation; ease of system maintenance and management, but also can build system, choose different configurations to achieve high-performance system, vigilant multi-user concurrent access efficiency. This structure is the one to many leather body object for fear, organization, management and publishing system that consists of five separate function: content creation and entry, storage and management, access, and query, publish, and disseminate and rights management, the various electronic structure to wait with the traditional architecture of the library. This structure has the advantage of supporting efficient organization, management, and publishing a large number of multimedia information. The systematic use of library services to manage the system index and query data, use the object server to manage digital content. Digital images, music and television data in data often have large magnetic needle frequently Yin tonic used to name, to the extent possible, is placed in the near distance, the user can dramatically reduce communications costs and improve efficiency. Room client application the request made by the library to get the object server, then the object server to route the request to send the object by the client. Object server can be an ordinary file server, and then by object server to objects delivered to the requesting client. Object server can be an ordinary file server, a dedicated store and forward server, stream delivery video/audio server, or any combination of them. The structure of hierarchical storage management system will also such as disk and CD of these lower prices, performance, better secondary storage connection with reality in aPlay. Library servers use relational databases to meet its responsibilities. In this way, through the object management subsystem and object storage subsystem of logical separation, provides an independent multimedia content data management capability, which provides object-oriented data inventory management capabilities, but also has a regular relationship data inventory of high performance, and can act in different types of open environments, meet the needs of a variety of applications.