The TV set-top box, right?
It's used to decode digital TV signals
It can be interpreted as a set-top box that connects to the Internet to broadcast video (TV)
It's already becoming popular
Now it's free if you pay a certain amount of money for a program
As long as it's a purchased specialty channel, it's free of ads
Of course, you don't have to worry about viruses
It connects to the broadcaster's data center
How could it be a TV set-top box? to the broadcaster's data center
How can it be toxic?
Reference:
Set-top box
1. Definition of set-top box
There is no standard definition of a set-top box, but in a broader sense, any network terminal device connected to a TV set can be called a set-top box. From the analog channel adders and analog channel decoders based on the cable network in the past, to the "Velas" Internet set-top box that connects the telephone line to the TV set, the integrated receiver decoder (IRD, Integrated Receive Decoder) of the digital satellite, digital terrestrial set-top box, and the digital set-top box of the cable TV, all of them can be called set-top boxes. Cable TV digital set-top boxes can be referred to as set-top boxes. Narrowly speaking, if we only talk about digital devices, according to the main function of the set-top box can be divided into the Internet set-top box, digital satellite set-top box (DVB-S), digital terrestrial set-top box (DVB-T), cable TV digital set-top box (DVB-C), as well as the latest emergence of IPTV set-top box, and so on.
Digital TV set-top box is one of the information appliances, which is a kind of consumer electronic product that enables users to watch digital TV programs on existing analog TVs for interactive digital entertainment, education and commercialization activities.
2. Functions of digital set-top box
The basic function of digital set-top box is to receive digital TV broadcasting programs, and at the same time, it has all the functions of broadcasting and interactive multimedia applications, such as:
(1) Electronic Program Guide (EPG). It provides users with an easy-to-use, user-friendly interface and a way to quickly access the programs they want to watch, through which they can see the TV programs that will be broadcasted in the near future on one or more channels or even all channels;
(2) High-speed data broadcasting. It can provide users with stock market quotes, ticketing information, e-newspapers, popular Web sites and other news;
(3) Software online upgrade. Software online upgrade can be seen as one of the applications of data broadcasting. The data broadcasting server broadcasts the upgraded software according to the DVB data broadcasting standard, and the set-top box recognizes the version number of the software, receives the software when the version is different, and updates the software stored in the memory;
(4) Internet access and e-mail. The digital set-top box can easily realize the Internet access function through the built-in cable modem. Users can surf the Internet and send e-mail through the built-in browser of the set-top box. At the same time, the set-top box can also provide a variety of interfaces to connect to a PC, using the PC to connect to the Internet;
(5) Conditional reception. The core of conditional reception is scrambling and encryption, and the digital set-top box should have descrambling and decryption functions. In short, so far, a variety of value-added services have been developed around the three core functions of digital video, digital information and interactive applications of digital set-top boxes. See the following table:
Item Content
Basic Services Analog TV broadcasting, FM broadcasting, analog pay (scrambled) TV
Digital Video Satellite digital video broadcasting (DVB-S);
Terrestrial digital video broadcasting (DVB-T);
Wireline digital video broadcasting (DVB-C);
MMDS digital video broadcasting;
Digital video broadcasting; and
Multiple digital video broadcasting. MMDS digital video broadcasting;
Digital pay (scrambled) television (DPTV)
Digital audio IP telephony/fax;
Music (MOD);
Real-time audio karaoke on demand (KOD)
Digital data Information on demand (IOD);
Broadcasting in data (BIS);
Stock Market Securities Information Broadcasting (SIS);
VBI Graphic Television;
Application Downloading;
Remote Database Streaming;
E-commerce;
Home Banking
Interactive Multimedia Internet Access Service (IAS);
Tele-Education;
Telemedicine
Online shopping;
Online billing;
Electronic advertising;
Stock market securities services (SES);
Online (audio and video) broadcasting services;
Visual telephony and videoconferencing;
Multifunctional services for the community
3. Categorization and application of digital set-top boxes
Different operators and different set-top box manufacturers divide STBs into basic, enhanced and interactive types according to different application habits, and the division of STBs varies according to different levels of operators' understanding and application of digital TV. Most operators define basic STBs as those that only support video and audio services and receive EPG information, but do not support data browsing and other applications, which are placed in the so-called enhanced STBs; STBs with bi-directional functionality are defined as interactive STBs. In fact, it is very difficult to distinguish what is basic type and what is interactive type from the function, and there will be different divisions for different business purposes. The so-called basic type and enhanced type often use the same hardware platform, and the difference is only the software, although there are vendors who claimed that their STBs are interactive or can carry out interactive services, but there is not a kind of mature interactive in the country due to the reasons of the network. applications, the current so-called interactive applications basically remain on the basis of local interaction.
Selecting different chips constitutes different hardware platforms, equipped with other devices and interfaces are also different, which constitutes a wide variety of STBs. for example, adding a modem or network card to the STB constitutes a set-top box with two-way functionality; adding a hard disk constitutes a personal video recorder (PVR: Personal Video Recorder), and of course, it is not possible to use the STB for any other purpose, but the STB can be used for any other purpose. PVR: Personal Video Recorder), of course, all of these require the cooperation of software. On the same hardware platform by residing different software can also constitute a different application of the STB, and the diversity of the STB to meet the needs of different levels.
The development trend of STB
Large market space, tens of billions of dollars of output value to attract many businesses engaged in the production of STB manufacturing, it is estimated that there are more than 300 domestic enterprises are engaged in the production of STB, and as of the end of 2004, the country's cable digital subscribers about 800,000 or so, excluding the cumulative development of the previous more than 300,000, the actual last year, the new subscribers will not be more than 500,000 households. The new subscribers in a year will not exceed 500,000, the cruelty of the market competition makes the whole industry in a state of loss.
While operators are promoting digital TV on a large scale, engaging in the overall migration of the whole network, and distributing STBs to users for free, for which they have also created such models as the Qingdao model, the Foshan experience, and the Hangzhou model, etc., this has not brought prosperity to the STB industry, nor has it promoted the development of STB technology, but instead has caused a lot of confusion to the digital TV industry. How to adapt to the development of technology, grasp the direction of technological development, may no longer only manufacturers need to pay attention to the problem, perhaps more should cause the industry authorities and operators to pay attention to the need for all parties to make concerted efforts as soon as possible for the digital TV to create a good space for sustainable development.
Digital TV set-top boxes
Most of the set-top boxes currently in use in China belong to the basic category, which can receive digital TV programs and also provide some applications such as e-government services. With the development of digital TV technology, a new type of TV set with digital decoding function has been introduced, and is now in the stage of large-scale testing before production. This new integrated TV set, which combines the most basic STB and TV functions, will have a significant impact on the manufacturing of STBs and the operation of digital TVs. In the face of the huge production capacity of home appliance giants and new technology products, most STB producers will face the risk of reshuffling.
For operators, the emergence of all-in-one TVs has also changed operations. In the past, operators not only had to worry about program transmission, but also had to put a lot of effort into subscribers' STBs, and even carried heavy burdens for that, especially in the process of overall panning, and carried huge debts due to sending STBs, which may be well resolved due to the emergence of All-in-One. In the next 2 to 3 years, according to the national industry's plan, more than 35% of TV sets produced in China will come with STB function, which means more than 1,500 all-in-one sets will be put on the market every year, and the number will keep climbing later.
Set Card Separation
Set Card Separation and All-in-One PCs are almost a natural pair. The large-scale manufacturing of TVs not only improves product reliability, but also reduces the cost of production, and the basis of large-scale manufacturing is the consistency of the products produced, which is not only manifested in the hardware but also in the software. The variability of the software makes it impossible for manufacturers to mass produce set-top boxes as they do TV sets. So to realize scale manufacturing, CA is the first problem to be solved.
The meaning of the set-card separation technology is to make the digital TV receiving equipment (set) and CA smart card and its software (card) have nothing to do with each other, and the two are connected through an interface product (big card or CAM card), and the TV set and STB are reserved for this common interface. Before inserting the CA smart card, all TV sets and STBs have the same hardware and software, and the smart card must first be inserted into a CAM card adapted to it before it can be inserted into the TV set or STB to decode the corresponding program. Although on the surface due to the use of the CAM card increased user access costs, but because of the boundaries of the separation of the CA to the operator and the manufacturer have brought about a reduction in the use and manufacturing costs, and ultimately brought about a reduction in the cost of access to the user. Many advantages make the card separation become a trend of industrial development, the United States has taken the card separation as a standard for digital TV sets, and defined a mandatory schedule for this. For China, a large TV producer, card separation will also become the trend and standard of China's industrial development. The popularization of digital TV sets will help drive the development of digital TV subscribers as products are released to the market in bulk.
Interactive STB
While the all-in-one may replace the popular STB, in the development of digital TV, due to the continuous expansion of the business, the software of STB will also continue to improve, especially in the field of interactive, with the improvement of the middleware and the application of the STB becomes a low-priced hardware platform, which can be used to realize a variety of applications by replacing different software. For operators, interactive applications have huge business benefits and are the most important source of profit in the future, and the use of interactive STBs can help realize this goal. Interactive STBs also represent the highest level of set-top box technology development, and have tremendous room for growth.
PVR STB
In the STB with a storage device, you can store your favorite programs, this STB is the PVR. Although the PVR STB has not yet formed a certain market in the country, the strong growth of millions of units sold each year in foreign countries is a sign of the huge domestic market in the future, and with the passage of time, the demand will be more and more large.
Dual-decode or multi-decode STB
For domestic operators, especially in the process of overall panning, how to solve the user more than two TV sets to watch digital TV programs is a very headache for developers, although it can be achieved through mandatory administrative actions to one set of one card to increase the viewing fee, but not to allow users to understand this mode of operation, but also make the the promotion of digital TV programs face great resistance.
The dual-decoding STB is to use dual-decoding chips in one STB or to embed more than two decoding circuits in one chip with two demodulators, which in turn enables one STB to output two different programs, while the cost of the STB has only increased by 30% to 50%. The new product is a boon to those with more than two TVs, but it's not good news for operators who expect customers to buy more than two STBs and pay more than two program fees.
DVB and IP in one
The rapid development of IP technology poses a huge threat to digital TV, but in the short term the cost of the network makes it impossible to replace the two. Although there are so-called STBs with IP function in the domestic market, these set-top boxes are only integrated with NICs or with a retransmission channel, and since they can't satisfy the streaming media and other services, they are not quite a STB that combines DVB and IP into one.With the introduction and improvement of the chips with dual decoding function of MPEG-II and MPEG-IV, there are such STBs in foreign countries that have already been launched on the market. With the introduction and improvement of chips with MPEG-II and MPEG-IV dual decoding function, such STBs have already been put on the market in foreign countries, which can be adapted to different network environments and have a broad development prospect. In addition, the development and integration of this technology may bring some unexpected changes, perhaps in the near future, with the development of network technology, a set of DVB and IP in one of the terminal products will become a member of the family, which is connected to the family's display devices, computers, and even other intelligent devices, to meet the needs of family information technology.
4, the key technology of cable TV digital set-top box
Hardware structure of the set-top box
From the composition of the digital TV set-top box, it mainly consists of two major parts: hardware and software.
From the structural point of view, the set-top box is generally composed of the main chip, memory, tuning demodulator, backhaul channel, CA (Conditional Access) interface, external storage controller, and video and audio outputs and other major components.
Tuning demodulator
Tuning demodulator part of the role of the transmission of the modulated digital signal demodulation into the transmission stream, the different tuning demodulator constitutes a different digital set-top box, such as satellite set-top boxes for QPSK demodulation (DVB-S), for QAM demodulation of cable digital set-top boxes (DVB-C), and digital terrestrial transmission OFDM demodulation (DVB-C). digital set-top box for terrestrial transmission (DVB-T). The more popular tuning demodulator manufacturers on the market are Thomson, Sharp, etc. Although there are some domestic manufacturers producing tuning demodulators, the market share is very small.
Main Chip
With the development of chip technology, more and more manufacturers will set-top box functions more integrated in a main chip, for example, most of the manufacturers now will be the CPU, decoder, demultiplexer, graphic processor and audio-visual processor integrated in the chip, and even some of the chip makers represented by Philips will be the tuner demodulator is integrated in the chip, forming an integrated chip solution, effective and efficient. The new chipset is an integrated solution that effectively reduces device costs and improves reliability.
In the main chip, the received transmission stream is first demultiplexed according to the flag information conveyed by the transmission stream, and then the program stream is descrambled according to the descrambling information conveyed by the CA smart card, and the descrambled TS stream is sent to the audio-visual decoder to decode and reduce to AV signals for output, and at the same time, the various types of system data tables that are multiplexed into the TS stream are also separated and sent to the set-top box processor for output. The set-top box processor outputs them separately.
Additionally, the integration of the CPU and graphics manager in the main chip allows the STB to perform more functions, and it can run a variety of software to accomplish many tasks, such as stock reception, web browsing, etc. It can also realize 2D and even 3D graphics processing through the graphics manager to provide users with more beautiful interfaces, and realize a variety of high-definition applications, such as interactive games.
Because the CPU is the core of the chipset, it is usually the performance of the CPU that determines the performance of the chipset, and the performance of the CPU is generally determined by the main frequency, and the higher the main frequency, the higher the performance of the CPU. Currently the fastest CPU frequency has exceeded 400 MIPS, even the popular and most basic set-top box in the market, the main frequency of the CPU is more than 50 MIPS. CPU speed and the business system running on it has an inevitable connection, if you need to run an HTML browser in a STB, 100 MIPS may be the minimum requirement for the CPU, of course, this also requires the cooperation of memory. memory is also required.
Memory
In some ways, a STB is similar to a PC, or even a simplified PC, and the most similar aspect of both is memory. For STBs, memory is mainly divided into Flash memory and SDRAM memory, Flash is used to store the system software, driver software, application programs and some user information of the STB, and the content can be retained when the system is powered off, meanwhile, Flash can be used to update the software contained in the STB through the online way, so as to achieve the purpose of upgrading the software of the STB, SDRAM is mainly used to store application data. Store application data. Many functions of the STB require memory to realize, such as graphics processing, video and audio decoding and demultiplexing, etc. The size of memory configuration varies for different application requirements. Although the configuration of large capacity Flash and SDRAM can reserve enough memory space for future business systems, memory is not the factor that determines whether the software can run or not, it needs to work with the CPU, and unrealistically high configurations will only result in a waste of resources and will not help to improve the performance of the STB.
External storage devices
External storage devices are generally referred to as external hard drives, and high-capacity hard drives can be used to store program streams in order to meet the user's individual needs. Whether or not an external hard disk can be attached to an STB is generally determined by the main chip, and only when the CPU's processing power reaches a certain level is it possible to support hard disk reading and writing, and hard disk reading and writing also requires more memory space.
Smart card interface
Reading data from CA smart card for descrambling of digital TV programs via card reader, especially in the development of pay TV, is an essential part of most STBs. In addition to the standard card reader, in some STBs the reading of the CA smart card is also accomplished by using the Common Interface (CI), a standard interface defined by the DVB organization for the interface between the set-top box and the separate hardware module. The application of this technology, which originated from PCMCIA, enables the mass production of set-top boxes and brings changes to set-top boxes with a wide range of applications.
Return communication interface
With the expansion of set-top box applications, the user's demand for set-top boxes has not only stayed on simply watching video and audio programs, but also the interactive demand for set-top boxes embedded in the return device, which can include network adapters, modems and other communication interfaces to meet the user's information back to the front-end.
Other Device Interfaces
The development of new technologies has led to an increase in the number of physical interfaces for STBs, such as RS232 interfaces, infrared remote control interfaces, wireless keyboard interfaces, Wi-Fi interfaces, and so on, which enable STBs to connect with a wide range of devices such as camcorders, DVDs, PDAs, and so on.
Software system of STB
As a client system, STB, in addition to a good hardware platform, needs to be equipped with different software systems in order to complete various tasks. The software in a set-top box can be divided into three main layers: the application layer, the intermediate interpretation layer and the driver layer, each of which contains many programs or interfaces.
Driver Layer
The driver layer includes the drivers and API interfaces for the hardware of the set-top box, which are mainly used to complete the operation of the hardware devices.
Intermediate Interpretation Layer
Intermediate Interpretation Layer translates STB application commands into CPU-recognizable commands, and then mobilizes the hardware devices to complete the corresponding operations through the driver layer. This layer includes the embedded operating system, middleware, CA-resident software, and so on. Although the use of middleware can bring great benefits to the design and application of STB software, the high cost of using, the increase in the demand for hardware and technical immaturity make the middleware rarely used in China. Currently many software designers use direct calls to the driver layer of the software to write applications, which can meet the needs of the moment, but with the increase in application requirements, the use of middleware in the STB is a good solution.
Application layer
The application layer can be divided into two parts: resident applications and downloadable applications. Different STB software design concepts make these two parts contain different applications, and reasonable planning of the composition of these two parts will help to improve the reliability of the STB and the corresponding time. At present, there are fewer applications in domestic STBs, mainly focusing on EPG, data broadcasting, stocks, simple downloadable games, etc. The charm of digital TV does not lie in watching TV, but in this kind of business applications based on the digital TV platform, which will improve some of people's daily life customs. With the construction of two-way networks and the popularization of interactive applications, there will be more and more interactive-based application software, which will also bring unpredictable value-added income to operators. The technical content of cable TV digital set-top box is very high, which centrally reflects the multimedia, computer, digital compression coding, scrambling algorithm, encryption and decryption algorithms, communication technology and network technology development level.
※Scrambling technology
Scrambling technology is used to encrypt and decrypt digital programs, and its basic principle is to use scrambled control word encrypted transmission method, and the user side decrypted by using IC card. In the MPEG transport stream, there are two data streams related to control word transmission: authorized control messages (ECMs) and authorized management messages (EMMs). The control words encrypted and processed by the service key (SK) are transmitted in the ECMs, which also include program information such as program source, time, content classification and program price. The service keys encrypted with control words are transmitted in the authorization management, and the service keys are encrypted by the subscriber's personal distribution keys (PDKs) before transmission. The EMMs also include the address, subscriber's authorization information, such as the programs or time slots that the subscriber can watch, and the subscriber's payment of the subscription fee, and so on. The user's Personal Distribution Key (PDK) is stored in the user's Smart Card. At the subscriber side, the set-top box obtains the PID values of EMMs and ECMs according to the CA-descriptor in the PMT and CAT tables, and then filters out the ECMs and EMMs from the TS stream and sends them to the Smart Card through the Smard Card interface.The Smart Card reads the subscriber's Personal Distribution Key (PDK) firstly, decrypts the EMMs with the PDK, extracts the SK, and then sends the SK to the Smart Card through the Smard Card interface. Smart Card first reads the user's personal distribution key (PDK), decrypts the EMMs with PDK, takes out the SK, then decrypts the ECMs with SK, takes out the CW, and sends the CW to the descrambling engine through the Smart Card interface, and the descrambling engine can descramble the scrambled transport stream with the CW. Scrambling techniques are categorized into same-density and multiple-density techniques. Simultaneous scrambling technology is the application of two or more Conditional Access (CA) systems to the same network platform, from the perspective of the cable TV station is to realize the choice of technology and competitive environment. Multi-crypto technology requires set-top boxes to adopt CI technology to realize that the same set-top box can receive encrypted programs from different CA systems. From the subscriber's point of view, it will not be limited by the purchase of a set-top box that is a CA, and the subscriber still has the possibility of choosing the services of its CA.
5. Conclusion
Digital set-top box is not only a user terminal, but also a network terminal, which enables analog TV sets to shift from passive reception of analog TV to interactive digital TV (e.g., video-on-demand, etc.), and access to the Internet, so that users can enjoy a full range of information services, such as TV, data and language. At present, some people think that the set-top box is used to make the TV set go online, which is a misunderstanding. In fact, the digital set-top box is a member of the broadband integrated information network before the popularization of digital TV sets. With the development of digital technology, multimedia technology and network technology, will prompt the digital set-top box built-in and the whole cost down, so that most users in the ordinary analog television sets to achieve both entertainment, but also to access the Internet and a variety of services.
In short, the set-top box as a digital TV iconic products, has a broad space for development. With the development of digital TV applications, chip technology and software technology, STBs are bound to become more and more powerful, and can carry out more services for operators and users to meet different levels of demand.