What is IPTV?

With the continuous progress of information communication technology and IP technology, as well as the national strategy of vigorously promoting informatization, the Internet and broadband communication networks have been greatly developed. The number of netizens exceeds 654.38 billion, and the number of broadband users exceeds 40 million. The IP phone, video conference, videophone, audio and video download, e-commerce, e-government, interactive games, video on demand, network TV, travel consultation, digital library, digital museum, search engine and other services on the Internet and broadband communication network are developing vigorously. With the development of Internet and broadband network, Internet TV (or IPTV) came into being, which is a new service produced by the integration of Internet service and traditional TV service. Before the birth of IPTV service, there was already a streaming media technology closely related to it. Streaming media technology can provide continuous, strictly timed, quasi-real-time and one-way multimedia information transmission service with the help of information flow between service providers and users, and has the characteristics of big data services such as distance education, TV programs and MP3. From the user's point of view, an important technical feature of streaming media technology is that the media stream is a one-way communication from the network to the user. In the process of continuous network transmission, users can cache and play at the same time without waiting for the whole content to reach the user's local area (this is obviously different from the current file mode, such as FTP). Sometimes the industry equates IPTV service with streaming media service, but there are some obvious differences between them. First of all, IPTV is a user-oriented term that describes services. Streaming media is network-oriented, which describes a technical means used in realizing some services (or applications). Secondly, IPTV is generally realized by streaming media technology, but not necessarily by streaming media technology (such as program clips with very small data); Streaming media technology can be used to realize IPTV service, but it can also be used to realize other services with large data transmission, such as video teaching, telemedicine, video on demand and so on. People from different industries, organizations or knowledge backgrounds have different understandings of ipTV, including the meaning of "TV", the carrier of "IP" and the relationship between "IP and TV". The first choice is the understanding of "TV" under the new technology: 1) Content-centered definition: The source of IPTV programs is the same as that of traditional TV, for example, they should all come from TV stations. 2) Terminal-centered clarity: Ordinary or high-definition TV sets are used as display terminals after being processed by set-top boxes (STB). With the development of technology, it is obvious that TV can be used not only to watch TV programs, but also as an integrated terminal for other businesses (such as games, stock market, teaching and medical care). In addition, TV programs can be watched not only on TV, but also on devices such as PC and mobile phone. Therefore, the author thinks that "TV" in IPTV should be defined with the content as the center, which only means that the program source is TV, and it is not necessarily related to whether the display terminal is a traditional TV (standard definition or high definition). Secondly, there are at least two differences in understanding the degree of "IP" in IPTV: 1) horizontal. Is the end-to-end (that is, the processing from the channel coding of the program source to the user's display terminal) all IP-based, or can it be called IPTV as long as it is partially IP-based (such as IP-only bearer network)? 2) Vertical direction. Does IPTV IP all the "control plane", "management plane" and "user plane" in IPTV services (for example, they are all carried in an IP network)? Or whether one or more planes are IP-oriented (such as "data plane" or wired, while the control plane takes IP network), can it be regarded as IPTV? The process of "IP" of TV technology has just begun. At present, these two methods coexist. Finally, the relationship between "ip" and "TV". According to the above introduction, there are at least two views on the relationship between "ip" and "TV":1) "IPTV = IP+TV" mode: in this realization mode, the uplink control of IPTV and the media stream of IPTV work in IP network and wired network respectively, which are completely parallel from the network point of view. From a technical point of view, it can be understood that the "data plane" of IPTV works on the broadcast cable, and the "control plane" and "management plane" of IPTV work on the IP network. 2) "IPTV = TV over IP" mode: that is, all services including TV are carried on IP, and of course all three planes of IPTV, including data plane, control plane and management plane. Inconsistent understanding of IPTV concept is the root of many IPTV-related problems at present, which leads to the difficult determination of industry supervision boundary and unclear responsibility; The division of labor in industrial chain is not clear; Unclear business operation mode and operation subject also lead to disunity in business, product technology and standards, and difficulties in interconnection. Therefore, it is urgent to unify the understanding of IPTV.