Friday, April 8, 2011

College】 【weak】 VOD video on demand technology..

<br> VOD video on demand technology <BR> VOD (Video on Demand) is a short video on demand technology, also known as interactive television on-demand system, which means users need to play according to the corresponding video, to fundamentally change the user .Over the past lack of passive TV viewing. .When you turn on the TV, you can not see ads for a program does not hurry, always want to watch content on demand directly, as if just playing into his home VCR or VCD machines in a new film, but you do not .need to purchase a tape or VCD disc, do not need VCR or VCD machine. .This is the information technology to bring your dream, it will be video programming through a multimedia network in accordance with the wishes of individuals to every household. .Looking at the application of broadband networks, VOD Most people live close to, but also the largest of its technical difficulty. .Take the words of China Telecom is the high road with, it is necessary to run a car, VOD broadband multimedia network application is the most eye-catching car. .VOD technology can be applied not only to broadband networks in telecom, but also can be used in LAN area and cable broadband networks. .Today, intelligent community in the construction process, the computer network cabling has become the essential part of the user can plot a computer, TV (with set-top box), etc. to achieve VOD video on demand applications, enriching the cultural life of the people; cable through .two-way transformation, allowing the majority of TV users to broadcast video cable network. .As a VOD system consists of three parts: server server side system consists of video servers, file management server, internal communications subsystems and network interface. .File management server is mainly responsible for customer information management, billing, video materials, finishing and security missions. .Completion of internal communication subsystem main information transfer between servers, back-visual materials and data exchange. .Main achievement of the network interface for data exchange with external networks and providing user access to the interface. .Mainly by the video server storage devices, high-speed cache and control management unit, whose goal is to achieve data compression and storage media, and according to media requests for information retrieval and transmission. .Video server and data server has many traditional significantly different, need to increase the number of dedicated hardware and software features equipment to support the special needs of the business. .For example: media, data retrieval, real-time information flow and information transfer the encryption and decryption. .For the interactive VOD systems, server systems also need to implement the processing of user requests in real time, access permissions control, VCR (Video Cassette Recorder) functions (eg, fast forward, pause, rewind, etc.) of the simulation. .Network systems, including network backbone network and local network in two parts. .Because it is responsible for real-time transmission of video information stream, so the continuous media web services that affect crucial parts of the system performance. .Meanwhile, the media service system, the network portion of the huge investment and therefore should not only be considered in the design of the current high-bandwidth media applications on demand, but also the future development needs and backward compatibility. .Currently, the system can be used to establish such a service network of the main physical medium is: CATV (Cable TV), coaxial cable, fiber optic and twisted pair. .The network technology used in the main are: Fast Ethernet, FDDI and ATM technologies. .Currently the client system, according to the different functional requirements and application scenarios, there are three VOD systems: NVOD, TVOD, IVOD. .NVOD (Near-Video-On-Demand), may be called near-style on-demand television. .This on-demand television way: multiple video streams in turn start a certain time interval to send the same content. .For example, a dozen video streams every ten minutes to send the same to start a two-hour television programs. .If you want to watch this television program might need to wait, but the longest no more than ten minutes, they would choose their nearest the starting point for some time to watch. .In this way, a video stream may be for many users to share. .TVOD (True Video-On-Demand), called the true on-demand television, it really supports the point that place. .When the user requests the video server will immediately send the user to the video content. .If another user made the same demand, video server will immediately transfer him to start another video stream the same content. .However, once the video stream to start playing, we should continue to play continuously until the end. .In this way, each video transfer for a customer service. .IVOD (Interactive Video-On-Demand), known as the interactive on-demand television. .Than the first two methods are much improved. .It not only can support the point that release, but also allows the user interactive control of video stream. .At this point, the user can operate like a traditional VCR, as to achieve the program play, pause, rewind, fast forward and automatic search. .Only use the appropriate terminal device, the user can with a service or service provider to contact and interoperability. .In VOD system, the need TV and set-top boxes (Set-top Box), in some special systems, may also need a large capacity hard disk with a computer to store video files from the video server. .Client system, in addition to involving the appropriate hardware, but also with related software. .For example, to meet the needs of the user's multimedia interaction, client systems must be modified interface. .In addition, during the continuous media playback, media stream buffer management, audio and video data, synchronization, network outages and problems of coordination studio interruption need to be fully considered. .Although very attractive VOD service can be seen, but its implementation technology is not a "easy nut to crack." .But as the network technology, computer technology, storage technology, the rapid development of VOD customers to enjoy the full fun of the day is not far off. .By that time, on-demand users will operate the remote control, push the button, you can watch and enjoy all wishes come true in their favorite programs, and are free to adjust the screening schedule, speed and so on. .The emergence of VOD makes TV becomes a random access to information to the media, more like a book or a newspaper, you can browse, you can adjust, no longer restricted to a particular time, date, and fixed limit program .. .Although, VOD initial appearance of the user in order to better meet the needs of independent video to watch, but as the VOD technology continues to progress, and its wide range of applications of popular culture and business model will have a strong influence. .VOD can not only provide end users with a variety of media, information flow, to expand people's access to information to enrich people's spiritual life; but also in hospitals, hotels, airplanes and other places of entertainment, the company's staff training, long-distance market research, company .areas of the advertising business will be gradually filled with VOD technology, new applications. .<BR>.

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