Interactive TV is a two-way TV. Users can respond to information through the information window on the TV screen, so that viewers can establish a two-way relationship with the information or programs on the TV screen.
In 2024,IPTV (Interactive Network Television) launch ads were completely canceled.[1]
By the end of 2023, there are about 400 million IPTV users, and the sharing revenue of IPTV platform is 17.471 billion yuan, up 2.90% year on year.[2]
Interactive TV is a kind of TV controlled by the audience. The audience can make choices between programs and within programs. It is a new type of asymmetric duplex TV technology.This is a two-way TV. Users can respond to information through the information window on the TV screen, so that viewers can establish a two-way connection with the information or programs on the TV screen.
Inter program interactive TV can be called VOD (Video On Demand), which can also be divided into TVOD (True Video On Demand) and NVOD (Quasi Video On Demand),Near Video On Demand)。In true on-demand television, each user owns a set of programs, and everyone needs to get a timely response. The programs stored in the information center and the video server of the television station can be controlled at will.Its replacement is quasi on-demand television.NVOD is to play a set of programs from the beginning at regular intervals.When a user watches a TV program, the switch connects the user terminal with the channel that will be broadcasted from the beginning recently, and the user's waiting time will not exceed a certain time interval.NVOD is much cheaper to implement.
In program interactive TV is also called full interactive TV, which can send the user's request response to the user in time.The information sent to users includes: video, image, voice, text and data.Compared with interactive TV between programs, it costs too much to implement and is seldom used.
The difference between interactive TV and ordinary TV.
(1) Ordinary TV mainly depends on the hardware structure, while interactive TV focuses more on the software control of the system on the basis of a certain hardware structure.
(2) Ordinary TV functions cannot be expanded.Interactive TV has built-in intelligent platform, and its application functions can be continuously expanded and updated.
(3) Ordinary TV can only receive radio programs passively.Interactive TV can not only watch normal TV programs, but also actively provide instant messaging services.Such as electronic program guide, current affairs news, entertainment and other network information.
(4) Ordinary TV cannot connect to the Internet.Interactive TV realizes the connection with the Internet.People can browse the rich information resources that the Internet can provide while relaxing.
2. Architecture of interactive TV
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As shown in Figure 1, the architecture of interactive TV.The interactive TV system is most commonly used for the interaction between programs. It can provide high-quality digital compressed VOD TV programs through the telephone system, cable TV system, cellular TV system, hotel pay per view system and hybrid system.
Figure 1 Architecture of Interactive TV
The VOD system needs to meet the following requirements:
① It supports 200~78000 users.
② The system must provide services to all user equipment at any time, and can support different users to select 20~2000 program resources.
③ The system must allow real-time interaction between users and the system. The basic services provided to users should include: video entertainment programs, video education programs, interactive games, mixed media information services and shopping services.
④ The system must have basic navigation functions, allowing users to select services in the VOD system. The navigation system must be simple to use, and excellent graphical user interface support software should be selected.
⑤ Each residential area must support more than one interactive user device.
⑥ The use of open set-top boxes is conducive to different compression and decompression algorithms, can allow different systems to be compatible, adapt to the resolution and aspect ratio of different televisions, and adapt to the further development and update of technology.
To illustrate the architecture of the VOD system, the block diagram of the general on-demand system is given first, as shown in Figure 2.
Figure 2 General VOD system structure block diagram
Its main components are:
·User request computer and accounting computer;
·The set-top box located at the user's location.
·Video server;
·Encoder/router;
The detailed general VOD system structure is shown in Figure 3.It divides the system into program distribution equipment and user equipment.
Figure 3 More detailed general VOD system structure
2.1 Video server
Video server is the most important part of the system, and also the most expensive equipment.Its biggest characteristic is that the data stream is required to be stable, interactive, reliable and extensible.Its performance requirements shall meet:
① Real time error correction function;
② Using sequential addressing to adapt to the inherent characteristics of video data;
③ Utilize the advantages of disk broadband to generate multiple RF streams from one disk (meet VHS quality, and generate 3-18 sequential return RF streams from one disk drive);
④ Provides a simple command set suitable for video recording and replay.
The main functions of the video server are:
① Large capacity video data storage;
② Program retrieval and service;
③ Fast transmission channel.
Three basic server structures have been developed for the on-demand TV system:
·A video server implemented on a general host;
·Video server implemented with tightly coupled multiprocessors;
·The specially designed multithreaded video server is also called tuning video server.
2.2 Encoder and router
Encoders and routers encode program and service data according to the needs of users, and assign them to users after routing.The system allocates programs and service data to different twisted pairs for spatial multiplexing according to the needs of users. Each twisted pair carries a program to the user's home.Time division and frequency division multiplexing methods can also be used to send programs to the destination, then to the signal separator and decoder in the user's set-top box, and finally to the user's TV.The program is best realized in the packet switching network, which is automatically realized by the router. Each packet contains destination address, information source, program address and other information.For digital video distribution, asynchronous transfer mode (ATM) may be the best method.
2.3 User request and accounting computer
In the VOD system, each user request computer can support 6000 users, and multiple user request computers can add 6000 users several times to the VOD system.Each computer needs enough physical space to support 6000 19.2kbit/s logical ports, and has the ability to allow packet communication at the same time.The computer will respond immediately or nearly immediately through the set-top box, just like in a multi-user time-sharing system.When immediate response is not available, some questions or other short programs need to be inserted, which will still make users feel an immediate response.The delay from selecting an item to receiving a new menu or program will not exceed 6s.The user's request computer and accounting computer also need to solve the service management, which includes service types, update and modification services, and charges for various service items.
2.4 Basic requirements of VOD service for set-top box
In the VOD system, the digital set-top box is the most important device in the current user terminal, and also the only device in the user terminal in the whole system.The basic requirements of VOD service for set-top boxes are:
① Receive, coordinate and demodulate digital modulation (QAM, VSB) signals;
② Able to complete forward error correction (FEC);
③ MPEC-2 decompression (including voice decoding);
④ Advanced graphical user interface (GUI), easy to query and retrieve programs on the screen;
⑤ VOD/TV selection function.
Advertising governance
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In 2024,IPTV (interactive network television) startup ads were completely canceled, and the startup duration was reduced from 118 seconds at most before governance to no more than 35 seconds.[1]
development history
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By the end of 2023, there are about 400 million IPTV users, and the sharing revenue of IPTV platform is 17.471 billion yuan, up 2.90% year on year.[2]
