1, IPTV Realization Broadband digital TV, also known as IPTV, or BTV, the interactive television network, is a use of broadband Internet, multimedia and other technology, and to home users, including a variety of interactive digital television services, including the new technology. It is well adapted to today’s trend of rapid development of the network, full and effective use of existing broadband network resources.
In the current commercial broadband networks, users at home can enjoy IPTV services in two ways:
(1) Computer: In this mode, the user access to the Internet through computers at the same time, you can listen to the radio or music, or directly on the computer watching TV or movies on video.
(2) Network set-top boxes (STB) + regular TV. New user home network set top boxes (STB), provided by the set-top box AV interface, the direct and ordinary television connected to the user by controlling the choice of access to broadband Internet television set-top box program.
PC users can enjoy both traditional and online games INTERNET data services can also be converted through specialized equipment STB, with a normal TV watching TV, movies and other broadband video programming.
2, IPTV in key technology IPTV is essentially the application of streaming media in the broadband network transmission and distribution, the development of IPTV applications and key technologies by applying the following results.
(1) broadband access technologies: the rapid development of broadband access technology for the transmission of media stream provides a path.
Used in the current broadband access technologies, DSL is provided through regular telephone line broadband data services technology. We used the ADSL (AsymmetricalDigitalSubscriberLine, Asymmetric Digital Subscriber Loop) technology to provide downstream bandwidth 8M, ITU-T’s G.992.1 ADSL standard is already on a detailed definition. With the rapid development of technology, ITU-T another in June 2002 and January 2003 launch of two next-generation ADSL standards: ADSL2 (G.992.3) and ADSL2 + (G.992.5). ADSL2 support the maximum downlink rate 1.3M/15M, while support for ADSL2 + the maximum downlink rate of up to 1.3M/24M. Higher bandwidth for the transmission of large amounts of streaming possible.
(2) IP multicast routing: strong support for streaming media distribution.
IP multicast routing technology to achieve efficient IP network, multipoint data transmission. Can effectively save network bandwidth and reduce network load. Multicast allows a sender to one or more (multicast source) while sending the same data packet to multiple recipients of a network technology, is an increasing backbone can not load the case, multiply business users to increase the number of effective programs, it has become the first choice for high-volume video service program. In IPTV applications, the use of IP multicast routing technology, can effectively distribute the media stream, reducing network traffic. Function of the current access device through IGMPProxy to achieve the user’s demand to join and leave other functions, so both the on-demand streaming media to achieve the distribution. And reduce the multicast on the bandwidth usage. With IP Multicast in the application of integrated access devices, most devices support IGMPsnooping and IGMPProxy function.
IGMPsnooping solve IP multicast network devices in the broadcast flooding the second floor is a basic solution. Network device through the second floor frame to listen to the client and the IGMP multicast routing protocol messages between devices, users get a list of multicast service information, the multicast user information based on the current forward to achieve the second floor of the multicast suppression The purpose of flooding.
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