Saturday, January 8, 2011
Weak current College】 【VOD structure model and the application of the cable television network】.
<br> VOD structure model and the cable network of <BR> with cable broadband technology, a variety of services based on broadband technology increasingly familiar and attention, and video on demand (VOD) is one of the .the application of distinctive one. .The full name of VOD Video On Demand, the video-on-demand technology, also known as interactive television on-demand system, which means the video stream playback as needed. ."In time of want to see want to see the show" This is the most suitable for users of appetite, and is the most attractive place on demand business. .Users can choose according to their own wishes to watch TV programs, a fundamental change in the past lack of passive television viewing. .Users do not have to comply with the traditional schedule, do not sit in front of the TV for a TV show waiting eagerly to see, turn on the TV you can directly click the hope that the program and at the same time without commercial interruptions, the full realization of the control by the user .access to information initiative. .Figuratively speaking, the use of video on demand service like in your own VCR or DVD player as easy to watch program, the user can not only free calling program can also implement editing and processing programs (such as pause, fast / slow forward, search, etc.) .get with the program-related information, the system can even choose to store user memory and recommend programs to the user. .VOD services provided to users is far more than that, you can achieve Internet, send and receive e-mail, home shopping, travel guides, booking reservations, stock transactions and other functions. .Therefore we can say the emergence of this technology allows the user to press their needs to the organization of work and leisure time, the real control by the user viewing the initiative, and greatly enhance and improve people's quality of life and work efficiency, for the user to .that this is a new attempt. .Video on demand is the end of the nineties developed in foreign countries is a development of the entertainment industry with the rise of technology. .It combines the use of computers, communications, television and other technologies, the use of the network and the advantages of video technology, completely changed the way past the passive viewing of programs to achieve the program's on-demand viewing and any playback, set the dynamic video images, still pictures, sound ., text and other information as a whole, to provide users with real-time, interactive, on-demand service system. .Video on demand technologies, in a sense, is the video field of information technology revolution, is also a challenge to the traditional way of viewing, thus causing the cable industry and telecommunications industry's attention. .August 14, 2000, in Shenzhen, China's digital cable TV premiered successfully in 2000, 24 provinces, autonomous regions and municipalities cable TV network, national network in 2001. .China Radio and TV broadband network will promote the overall advantages of the cause of industrial transformation of radio and television and digital cable television development process. .Upgrading the HFC from the coaxial cable distribution network; from the HFC distribution network into a two-way HFC upgrade distribution network. .Country has more than 300 two-way HFC cable television distribution network companies in the online pilot integrated services for digital cable TV multi-functional development of a bridge. .Transformed into two-way HFC network in the HFC network, cable network company to carry out many radio and television, data transmission, Internet access, video on demand and other integrated services pilot projects achieved a successful experience. .Today, cable television network of multi-functional business, video on demand systems and digital set-top boxes are maturing into practical use, commercialization, has become the latest hot spot. .Video on demand is a multimedia digital two-way automatic mutual transfer system is a digital television, digital video compression, video servers, databases, multimedia computers and other technology as one of the automatic on-demand interactive TV. .In VOD systems, cable TV input of the user to install a digital set-top box (STB), STB to access Internet TV, or computer through the Cable Modem (Cable Modem), to a variety of free on-demand TV viewing .program. .The same time stock trading, shopping, education, e-commerce, e-mail and other information activities, video on demand is a two-way HFC distribution network the best choice. .First, video on demand system structure and composition of the VOD system consists of front-end systems, network systems and client systems of three parts: 1, front-end system front-end system in general by the video server, a variety of file management server and control network composed of some of the equipment. .A variety of file server to complete some major information management and billing users, as well as film and television materials management and security and so on. .Control network to complete some of the major kinds of information in a variety of servers and back office work for film and television transmission material and data exchange. .There are video servers and storage systems to build their management systems on a variety of controllers, whose goal is to achieve compression of data storage media, and media requests for information by the retrieval and transmission. .Video server with the traditional data server in many ways significantly different, you need to solve many problems, to support a variety of new features. .Meanwhile, its high-speed data transmission capacity to ensure that the user of a large number of films, video programs, games, business information and other services in near real-time access. .Its biggest feature is the starting point can watch the same people from different programs, thus avoiding the highlights of being a user exclusive. .2, the network backbone network and the network system consists of two parts, the local network system, continuous media web services that affect a critical part of system performance. .The current service system for the establishment of such a network physical media are: CATV coaxial cable, fiber optic, twisted pair and wireless networks. .Commonly used in the broadcasting sector HFC technology, broadcast programs in the CATV system. .3, the client system only using the terminal system, the user can with a service or Internet service providers *** for. .In fact, in the computer system, it is the PC with a display terminal + Cable Modem complete: in the television system, it is adding a television set-top boxes (set top box) to complete. .The client system, in addition to dealing with hardware issues, but also need to deal with a variety of software related issues. .Such as: interactive multimedia to meet the needs of the user, the client system interface must be modified. .In addition, during the continuous media studio, the media flow buffer management, audio and video synchronization, network outages and problems of coordination studio interruption need to be fully considered. .VOD system works as follows: the user starts playing the client requests sent through the network communication call, the uplink channel (cable TV) a request to the video server. .Received by the server's network card to reach the drive to the server. .After acceptance of a request, the server can access the storage subsystem ready for the program name, and demand in the single-user screen. .Users select the program, the server removed from the storage subsystem, a video content into one data stream. .High-speed transmission network to the client player, customer premise equipment by a multimedia computer + Cable Modem, or video on demand TV + STB + remote control composition. .Discussed in this article CPE is: TV + STB + video on demand remote control. .Second, cable video on demand system structure model and the application of the VOD cable television is digital-analog two-way cable TV network in the additional front-end VOD system (or the use of the original video server), digital compression encoder, QAM modulator, the use of front-end down .light hair and light collection part of the uplink, the use of digital to analog and digital two-way transmission system terminal as the carrier, the user easily in the home use of video-on-demand remote interactive access to the instructions issued, on-demand video server VOD system, the rich are stored in the program source, .Digital set-top box by the user is responsible for return coding user commands and downlink digital signal demodulation, decryption, provides user ratings, VOD system to automatically control a variety of broadcast programs and fees. .Video on Demand System model is divided into two types: the number of VOD-mode bidirectional transmission mode and the application of digital two-way transmission system VOD application mode. .1) two-way digital-analog transmission system <BR> VOD application mode which is based on the total front-end integrated information platform for two-way high-speed data, digital to analog data platform has a broadband high-speed ATM switches and IP protocol switching function, but also based on two-way data .the transmission of high-speed integrated services network. .The model: the total number of analog data front-end two-way HFC distribution network platform + + multi-function digital set-top boxes (one client device.) .Its summary of work process: the user-demand return signal uplink commands output by the video-on-demand remote control to multifunction digital set top boxes, digital set-top boxes which are of multi-line signal modulation, coding, demodulation, smart cards and other functions, the multi-function digital .set-top box output, enter the 5-65MHz (or 5-200MHz or 800-1000MHz) to HFC optical node upstream channel optical transceiver station, and then return optical transmitter output from the optical fiber and cable access to digital-analog data sent to the front-end platform for the return of light .receiver, the photoelectric conversion, the switch access video server, video server, digital signal output, the use of the total front-end platform for digital to analog data transmission and two-way HFC distribution network to the user digital devices, VOD and down the line to complete the transmission of signals to achieve .video on demand. .In the digital-analog two-way transmission system there is a VOD application mode, and the total number of front-end modules separately and combining data platform and application models, two-way digital-analog transmission and VOD transmission is shared transport channel to the digital terminal. .The model: the total number of front-end data platform + VOD system model digital compression encoder + + + Two-way HFC distribution network multifunction digital set-top boxes (one client device.) .Its summary of work process: the user uplink signal from the video-on-demand remote control command output to a digital set-top boxes, digital set-top boxes by the output signal into the upstream channel to the optical transceiver station, and then return optical transmitter output from the Access front-end optical fiber and cable sent to the total number of .the return module data platform optical receiver, return optical receiver output by digital compression coding to ATM, ATM switch by the number sent to the VOD system-on-demand systems, digital on-demand system based on user commands from the VOD video server scheduling automatic editing ., edited to digital broadcast television transmission system control center, control center by the digital broadcast sent by the implementation of digital on-demand systems to the program, subtitles, broadcast time. .The digital compression encoded, transmitted to the digital front-end processing, exchange, QAM-64 modulator output, sent to the common parts of the total front-end digital-analog, mixed, down light hair, optical, routers, output, access to distribution of two-way HFC .network to the optical node optical transceiver station, after the output of photoelectric conversion into four-way high 106dBuv FTTC or two-way FTLA user distribution network, the output from the BR-way splitter cable to the user access 75-5 multifunction digital set-top box, how it .Output interface, then all the way in which television, Road access computers, three-way access IP telephony, using frequency division multiplexing manner, on the digital-analog two-way transmission networks, the downstream channel and upstream return channel to exchange information with users, .two-way transmission of video on demand. .For digital multi-functional digital set-top terminal should have the following features: a two-way control channel, analog video channels, digital video channels in the premise, it features a digital tuner, QPSK / QAM demodulator, a microprocessor (CPU) ., MPEG-2 transmission, video and audio demodulation, interactive control functions (including the upstream digital modulation and coding), Intel network access, IP address, infrared remote control, printing, smart cards, multimedia synthesis modules and other functions. .This two-way HFC distribution network in the downlink TV channels at 200MHz-750 MHz design, can the transition from analog to digital transmission, and ultimately the family VOD and other digital features. .2) digital two-way transmission of the VOD application of the public network mode when the cable network is a digital, networked, automated two-way digital transmission when the public network transmission system, the VOD application mode: two-way front-end platform for digital two-way digital transmission utilities + .Network + all-digital set-top boxes. .The working process: digital front-end platform, various sources (including running the program, the digital collection, non-compilation, recording, storage, retrieval, output video and audio digital signal into the digital front-end input) input by the digital front-end .part of the demodulation, compression, coding, various types of servers, network-centric access to the central processor for processing (monitoring, program choice, conditional access, scrambling, network management) and all-digital platform ATM switching, the output part of the QAM-64 modulated .downstream channel mixed output of the digital signal stream, the downstream optical transmitter output optical digital signal stream, the router output, digital two-way transmission into the public network to the optical transceiver working platform (including network management, etc.), the photoelectric conversion output digital .signal flow into the two-way or two-way FTLA structure FTTC coaxial transmission network to digital terminal (digital multi-function set-top boxes), for the user to viewing and so on. .User's uplink signal (IP telephony, data communication host computer, or signaling instructions, or VOD), digital multi-function set-top box by the modulation, coding, switching the output of digital signals, each respectively, through the uplink channel to the optical transceiver mixed together work platform .output, by photoelectric conversion, access to digital front-end input section and all-digital ATM platform, the data signal, VOD command, IP telephony, Intel network by the exchange switch, respectively, into their own servers, thus completing the two-way digital transmission function. .Digital two-way transmission in the public network, must use frequency division, time division multiplexing mode, two-way transmission channel to complete the transmission of mission. .By the principle of the channel frequency range is: After the two-way digital transmission of digital public network uplink signal frequency range by the size of the region, the actual transmission of information request. .By frequency division method, the uplink frequency of the low-end digital channel is divided into the low 5-65MHz; low-high split into 5-200MHz; high-end split into 800-1000MHz data channel. .Downstream digital channel frequency range 200-750MHz. .TDM way, depending on the rate of digital signals using time division multiplexing digital signal composed of a stream, the modulated, respectively, to send upstream, downstream digital signal stream. .In the two-way digital transmission network, according to actual needs, frequency division and time division multiplexing method combining applications, select the best solution, applied to two-way digital transmission on public networks. .So that the full range of digital cable television a more complete integrated information network, into the modern digital home, to achieve its ambitious information superhighway. .Years ago in many developed countries and regions had been optimistic about VOD, have developed and experiments. .Than speaking, China's current building is still in the early stages of development VOD, although some cities in China have been small-scale experimental video-on-demand system, but most applications still luxury hotels, large office buildings, living quarters and other high-end LAN .Application based. .This was mainly due to higher VOD system requirements on the network for cable television VOD, it is to be achieved in the two-way network, as most are one-way cable TV network, so we must face the problem of bi-directional network reconstruction .and requires a huge human and material resources, but in the long run, video on demand with a huge potential market and prospects for the development of far-reaching, because the deeper point of view, VOD is not just video on demand problem, it represents the future full-function network .information and digital interactive application development trends, is a from the content, form a deeper level of interaction, but also digital cinema, interactive video news / advertising based on new applications, and has broad potential for development. .VOD is the future information superhighway short an important part of architecture is the future of information services in the broadband services of the soul. .To be sure, with the acceleration of information technology, VOD is also in conjunction with other information services, into our lives. .<BR>.