IPTV classic technology
IPTV program content can be divided into real-time video and existing stored programs. When the program content is processed or authorized by the DRM system, it is transmitted to the intermediate service provider through the broadband media transmission protocol, and the intermediate service provider transmits the video stream to the terminal user through the network in an xDSL/FFTx manner. On the user side, users rely on modems, personal computers, set-top boxes and other devices to play streaming video. In the whole system, the system operator is responsible for the management functions of electronic program guide generation, content encryption, content management, authentication authentication, billing, etc., and sends the media stream to the intermediate service provider. In addition, the normal operation of IPTV also requires a robust operational support platform, which mainly includes basic management modules such as system management, rights management, user management, content management, and resource management, as well as billing collection, program management, copyright management, and traffic management. System. This article refers to the address: http:// Video compression technology Due to the huge amount of video data, the amount of uncompressed digital video data is unrealistic for current computers and networks, so the key issue in the application of digital video in multimedia is the compression technology of digital video. Video is a sequence of images formed by consecutive image frames. Due to the limitation of scene transformation speed, there is a high correlation between adjacent frames. Therefore, the main method of sequence image coding is constructed by using motion compensation technology combined with transform coding. At present, organizations such as ITU and ISO have developed many successful video image coding standards, such as the still image compression standard represented by JPEG and JPEG-2000. Medium to high bit rate multimedia data coding standard represented by MPEG-1 and MPEG-2. Low-rate, very low-rate moving image compression standard represented by H.261, H.263, and H.264, and MPEG-4 with wider coverage for object-oriented applications. Generation letter coding standard AVS. These standards vary greatly in code rate, image quality, implementation complexity, error control capability, delay characteristics, and editability to meet a variety of multimedia applications. In the following table, we mainly summarize the video coding standards. A traditional block-based hybrid video coding framework is adopted, which includes a series of techniques such as intra prediction, inter prediction, transform, quantization and entropy coding to achieve high efficiency video coding. Inter prediction uses block-based motion vectors to eliminate redundancy between images, and intra prediction uses spatial prediction mode to eliminate redundancy within the image. Then, the visual redundancy in the image is eliminated by transforming and quantizing the prediction residual. Finally, the motion vector, the prediction mode, the quantization parameter, and the transform coefficient are compressed by entropy coding. The test results show that h.264 is 48.80% less than the H.263++ average encoding bit rate, 38.2% less than MPEG-4ASP, and about double the compression efficiency compared to H.263. The code stream structure of H.264 has strong adaptability, increases error correction and recovery capability, and can adapt well to IP and wireless network applications. In addition, Microsoft developed WMV9, compression efficiency and reconstructed image quality are comparable to H.264, and are currently applying to become an international standard. China is now developing an audio and video codec system (AVS) standard with independent intellectual property rights, and its coding efficiency and reconstructed image quality are also comparable to H.264. It is the development of video compression technology that makes it possible to transmit high-quality video signals over broadband networks. Multicast technology IPTV is based on two ways of receiving video streams: broadcast reception and on-demand reception. The bearer technologies of different receiving modes are also different. Broadcast reception is non-interactive, and multicast requirements are imposed on the bearer technology of the IP network. The on-demand reception has the characteristics of real-time interaction, and requires the IP network bearer technology to push the video stream to the user access network. IP Multicast sends IP packets from one source to multiple destinations, that is, copies of the information are sent to all recipients of a group of IP multicasts. The IP packets are transmitted to a set of hosts that make up the multicast group. The relationship between each member of the group that can be distributed among the members of each individual physical network multicast group is dynamic, and members can join or quit at any time. IP multicast can effectively save network bandwidth and resources, facilitate network capacity management and control overhead, greatly reduce the load on the sending server, and reduce congestion on the backbone network. CDN (ContentDeliveryNet-work) is a network for video content distribution. It is superimposed on the IP infrastructure network. By publishing content to the edge of the network, the nearest content delivery service works. The working principle is in the network. Each node places a content cache server, and the CDN center control system directs the user's request to the best service node according to the network traffic and the connection of each node, the load status, and the distance to the user, thereby greatly shortening the user's request. Respond to time and improve the stability of data transmission. stream media Streaming Media refers to continuous time-based media such as audio, video, and other multimedia files that use streaming technology in the network. Streaming media technology generally refers to the process of compressing continuous image and sound information on a streaming media server, allowing users to watch and listen while downloading, without having to wait until the entire compressed file is downloaded to their own machine. / Audio transmission, codec technology. Streaming media technology is not a single technology. It is a technology built on many basic technologies. The key technology for streaming media implementation is streaming. The main technical feature of streaming media is the use of streaming, that is, streaming content to the client over the network. Most streaming applications use multicast-based application layer protocols such as RTP/RTCP.RTP is a real-time transport protocol that provides end-to-end transport services to support real-time data transmission over single-target broadcast and multi-target broadcast network services. The transmission of real-time data is monitored and controlled by the RTCP protocol. Network TV set top box One of the basic ideas of IPTV is to combine TV broadcasting with the Internet, so that users can obtain information through the network while watching TV. This feature is now implemented through a set-top box. The network TV set-top box (NetTVSTB) can have the following functions: built-in operating system, which can be operated by infrared remote control; decryption of encrypted TV signals; decompression of digital video and audio signals; user identification and payment; download and run games and software Separate different programs on the same channel; connect to the Internet, send and receive emails, and more. STB has been widely used in interactive TV systems built in Europe and the United States, and has broad application prospects in China. At present, China's overall digital-to-analog conversion of cable TV networks in China's broadcasting and television systems, of which network TV set-top box technology is one of the key technologies. Although IPTV has become the driving force of Internet evolution, a series of problems are becoming a drag for further development of IPTV. One of the important issues is copyright protection issues (DRM). Digital copyright The digital content transmitted by IPTV has the characteristics of non-destructive low-cost copying, storage and re-transmission. People can use the digital technology and the Internet to copy and distribute program content in batches without any loss of quality, causing serious losses to the digital media industry. The cost of illegally copying and distributing digital media is extremely low, and copyright is vulnerable. Therefore, the lack of effective digital copyright protection mechanism will greatly hinder the development of IPTV. The current solution is the digital rights management DRM system. The solution provided by DRM mainly emphasizes the use of technology to control the distribution, transmission and use of digital products, so that digital products can only be authorized by authorized persons. The way, used within the period of authorized use. DRM not only refers to copyright protection, but also provides a complete solution for the transmission, management and distribution of digital media content. DRM is therefore a system concept that includes the use of digital copyright information, the management and distribution of copyrighted digital media content. Taihang Power begin to produce rechargeable battery since 1956, our Nickel Cadmium Battery capacity range is from 10ah to 1200ah. NICD battery has the properties of rigid construction, long service life,wide work temperature, resistance to overcharge and overdischarge, low self-discharge, high reliability and easy maintenance. Nickel Cadmium Alkaline Battery Nickel Cadmium Rechargeable Battery,Nickel Cadmium Alkaline Battery,Alkaline Nicd Batteries,Nicd Battery For Ups Henan Xintaihang Power Source Co.,Ltd , https://www.taihangbattery.com
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