Weak current College】 【IP set-top box functionality and development】.

<br> IP set-top box functionality and development <br> IP set-top box overview IPTV (Internet Protocol TV or Interactive Personal TV) also called interactive network TV, is the use of broadband network infrastructure to home TV or computer as main .terminal equipment, Internet, multimedia, communications, and other technology, through the IP protocol to home users including digital TV, and a variety of interactive digital media service of the new technology. IPTV business core framework primarily by content operation platform, business operation platform ., business carrying transmission networks, users, terminal network, composed of four parts. IPTV technology involves the video codecs, network distribution and digital rights management, Terminal Access, and other surface technology. IP set-top box is video decoding Terminal, the equivalent .of one's own embedded operating system of your computer. You can see from Figure 1, IP set-top box end through DSL or Ethernet access network, one end will IPVT across the network of media streaming, and other information is converted to analog audio outputs .to the TV, the TV-video on demand, Web browsing, games, and other functions, it has the computer's basic features such as data exchange, you can use remote controller or PC directly. IP set-top boxes composition and function of the .set-top box consists of two major software and hardware, set-top box hardware contains main chips, memory, tuning modem, return path, CA (Conditional Access) interface, external storage controllers, and some audio output, etc. The software is .divided into the application-tier, middle tier and driver layer explained three layers, each layer contains many programs or interface, and so on. Unlike traditional digital set-top box, IP set-top box for video, voice, data, integration of .the three, the so-called triple play services (Triple Play Service). IP-STB system architecture consists of three separate subsystems: TV Unit, PC unit and the conditions of access (ie encryption system, CA). TV tuners and subsystem consists .of video codecs that are used to process digital streaming information; CA subsystem that service providers have the ability to control, you can user implementation approaches, to know what user when viewing programs; PC subsystem are modular design, STB designers can according to their needs .and increase or reduce the system's components, as IPSTB's objective is to provide Internet services to function, so it's PC systems have to provide the TCP / IP protocol stack, and has a better storage solution. From here we can see that the IP set- .top box functionality includes the following three areas: support for current LAN or DSL network transmission, reception and processing of IP data and video streams; support MPEG, WMV and Real, and so video decoding; <br> <br> Support user authentication function ., through interaction with the IPTV system for user access control, billing and other administrative functions. IP set-top box of classification according to the hardware, software, IP set-top box has a different classification 1. classification of hardware-based IP set .-top boxes, according to the Foundation using CPU chip, can be divided into the following three ways: (1) based on specific chipset (ASIC / SOC codec chip), set-top box dedicated chipset in addition to the processor, in the .chip also integrates a number of other IP (Lntelligent Property) module, such as Video in, Video out, Audio in and Audio out, etc, there are image compression hardware acceleration module, etc. As a dedicated video compression chip carry fixed compression module ., fixed approach and fixed microcode, so traditional ASCI / SOC of set-top box products less expensive, but because the whole hardware chip solution enables carriers to adopt software upgrades to improve product performance, in addition to this set-top network adaptability also has .a big problem. (2) based on the x 86 platform based on the x 86 architecture CPU embedded systems have the following advantages: first, it can be on different file formats for encoding and decoding; two is the x 86 architecture CPU has a .complete range of application software, low maintenance costs; the third is based on the x 86 architecture for embedded system can be easily shared with PC resources. (3) based on multimedia processor technology based on the x 86 platform approach is used to occupy most .of the CPU processing power. Therefore, some of which do not fit in this way. So the emergence of multimedia processor technology-independent model of set-top box. This chip high-speed computing capacity can achieve suitable for different protocol communication terminal. .Using these chips can easily implement MPEG video and audio processing, H.263 Video and DVD, set-top boxes, digital TV, etc. Due to the use of real-time video decoding chip, video processing speed has improved significantly, with real .-time encoding, full video processing delay, particularly suitable for camera system; system with an IDE, USB, PCMCIA and Ethernet interfaces, enables IPTV terminal function scalability enhances, memory footprint small, hardware, compact structure, cost is not high. 2. .based on the software of classification, the operating system is a set-top box core software, set-top-box operating system is not big, but it requires you to work in a real-time environment, and in smaller internal memory space, .this operating system known as real-time operating system (RTOS), at present mainly has the VxWorks, Windows CE, embedded Linux, etc. (1) embedded WinCE Terminal WinCE maximum characteristic is its compatibility with the Win32 API, which favours the use .of Windows application development environment, in addition, WinCE WMV player also can directly run on WinCE OS, many out-of-the-box Windows components with a little modification can be applied to the terminal network management as well as video stream control features such .as MMS, can fully shareAnd other Windows Media excellent results. Microsoft is now launching WinCE5.0, and opening up part of the program source code. In this open source project, Microsoft's open source program 250 million rows as evaluation kit, all personal, .manufacturers can download the source code be modified to use. The future is OEM manufacturers, according to perform authorization, payment period WinCE5.0 core each machine cost $ authorization number. As the market for new entrants, Microsoft emphasizes lower development costs. Microsoft WinCE .joined the archive system, IPv4/IPv6, WLAN, Bluetooth, and other networking capabilities, and features such as Windows Media Coder. But the drawbacks of this type of Terminal is not open source applications, Terminal uses WinCE shall pay royalties to Microsoft; in .addition, WinCE code huge, take up a lot of ROM and RAM, high-performance x 86 microprocessor support, all of which caused the terminal costs remain high. (2) embedded Linux Terminal this Terminal is often dedicated multimedia microprocessor core, supplemented with .Ethernet interface and video interfaces form the system. Multimedia microprocessor itself has embedded RISC (reduced instruction set CPU) to run the system software and application software, and real-time with MPEG2 or MPEG4 decoding chip, the Linux OS and the necessary video and various .auxiliary interface driver, you become a complete IPTV network Terminal application environment. Use the Linux development platform advantages first Linux source code, there are a large number of free excellent development tools and application software available, there is no need to pay for each example application .; second license fee has a large development groups, technical communication, software development and maintenance costs; finally, the Linux kernel itself stability, precision welding, fewer resources to run, have excellent network functionality, the large number of supported hardware. In short, .the price is the most significant feature. <br> However, such a system adapted to low bandwidth capacity limitations. Due to the use of a hardware real-time decoder, the decoder performance subject to chip technology development, and so saves QPEL and GMC .encoding tools, which makes the MPEG4 ASP high definition performance, suitable for DSL low bandwidth network transmission of benefits without access to give full play to the OS, some based on CI n μ L ux, decoder than incomplete MPEG4 ASP Terminal, line work bandwidth .in 3Mbit / s, in the same playback resolution D1, suitable for DSL networks low-bandwidth capacity than the Codec Terminal based WMVx. This set-top box prices lower, but because of the compatibility, system, server-side of the building and .the acquisition cost of the media file will be high. Wind River VxWorks is a United States company introduced a System for real-time operating system. VxWorks is a run on the target machine's high-performance, reduction of embedded real-time operating system. .It is famous for its excellent reliability and superior real-time performance is widely applied in telecommunication, military, aviation, aerospace and other high-tech technology and real-time demands extremely high areas, such as satellite communications, military exercises, trajectory guidance, .aircraft navigation, etc. Of course, depending on the set-top box functionality differences between high and low and prices, or the set-top box divided into basic, professional, General, etc. Set-top boxes and IPTV platform for IPTV set .-top box and the interface platform interface involves a lot of content, including user business processes can be divided into: authentication interface, billing interfaces and services grouped into three categories: using the interface. 1. certified interface authentication interface with network level authentication and .application-level authentication is the realization of the set-top boxes as early as the Internet, ie Internet users access the Internet. Per-user and network device communication, now use more network-layer access authentication method is divided into the PPPoE and DHCP .+ WeB. (1) PPPoE technology current PPPoE authentication technology in the Ethernet and ADSL access modes of the application of the most widely used, its networking principle basically the same, are using a switch or DSLAM will users access network, in the back of .the switch and the DSLAM equipment to set up PPP endpoints BRAS. End of the PPP connection broadband access server can be on the PPP connection is managed separately, on separate user online business time and flow of information and statistics, a variety of billing methods provide .the required user information online. PPPoE is essentially runs in the PPP over Ethernet protocol, the client and broadband access server has been established between PPP point-to-point channel. In other words, if the user host and enable multicast traffic between BRAS, .multicast data must be on the receiving end to BRAS as a replicate site, this will enable a large number of multicast data across the network and DSLAM equipment, contrary to the multicast in the first place. Therefore PPPoE access limits the multicast protocol exists, the .impact of video business. (3) DHCP + Web technology DHCP + Web authentication requires a DHCP server and Web authentication server, Host first through DHCP to get an IP address, and Web authentication server communication, or you can enable users to access some of .the internal server, and then, the access server will force the user to connect to the Web authentication server and browser shot certification page. In this page enter win and password, the Web Server as a Radius Client-side authentication information passed to the Radius .Server, to authenticate the user. Certification by, users get a new IP address of a legitimate, you can access the Internet or a specific network. In the DHCP + Web authentication mode, user host and access server does not have any similar PPP 3 .channel, there is no limit to the multicast protocol. If the user principal to the access server switch or DSLAM can support IGMP Snooping and multicast traffic can be easily carried out. But there are many DHCP own shortcomings, in particular the safetyProblem, how can .I ensure that user information validity, the authenticity is the DHCP key issues to be addressed. (4) improvement plan can thus be seen that the network layer authentication according to the degree of STB terminals support may use PPPoE or DHCP. However these two types .of authentication methods, are not able to meet the needs of IPTV business. Therefore, we need to now provide the authentication method the appropriate solutions, while guaranteeing IPTV business premise, as much as possible to reduce the large specification now network changes, to ensure .that existing business support. For STB terminals use PPPoE authentication, the main problems is the data issued. Thus can be tailored to the user's different business in different business distribution channel. That is, on the one hand requirements BRAS device supports IPTV business of PPPoE .authentication and its relevant unicast data channel via PPPoE issued; this requires the BRAS through certification information to distinguish between user types, and business equipment required to support the DLSAM multicast distribution and multicast group, also called STB device supports dual protocol stack. This can guarantee .the functionality of the original certification system, but also to ensure the smooth development of multicast services. For DHCP authentication mode, the main issue is to guarantee the security of DHCP access and authenticity, and this requires the text in the DHCP package OPTION82 options introduced .in; for more than one Terminal at the same time using DHCP, in order to distinguish between these Terminal, also introduce OPTION60 options. DHCP OOPTION82 option is typically used by DSLAM equipment will users of commodity information and device information to users of the DHCP packet ., DHCP servers by identifying OPTION82 is to perform IP address allocation policy or other policies. OPTION60 option is typically used by the Terminal with the different types of terminal you can set different OPTION60 to identify. By OPTION60 option, you can implement different terminal is assigned .a different address space. However, the introduction of the DSLAM OPTION82 need support, currently operational use of the device and do not have this feature, so the need for modification of network devices. Current solutions tend to use DHCP, and separate IPPOOL, the .programme can be configured for IP strategy for IPTV business and traditional Internet access service isolation. In the amount not IP-TV users, a smaller set assets to meet business requirements. (5) the application-tier certification application layer authentication enables IPTV set- .top boxes the user authentication process of the system, after the application-tier authentication users can consume, use the IPTV platform provides various types of services. Only secure application level recognition technology, to ensure that content providers safely wonderful content used in IPTV systems. .2. user interface user interface consumption needs to implement the system of consumption prices prompt, the user to confirm the purchase, system implementation with a complex process of consumption, in accordance with the billing and payment, the interface processes are different. 3. content .content using the interface use the interface to implement a user different from the content operation using services provided by application of IPTV systems have been increasingly rich, such as VOD, video on demand, games, karaoke, information retrieval, etc., along with STB .features of increasingly powerful, the network bandwidth is increasing, we have reason to believe that the PC's Internet applications through a set-top box is rendered in the user's TV set. IP set-top box development direction from a digital TV set-top boxes .(DVB-C), satellite set-top boxes (DVB-S), network, TV set-top boxes, set-top boxes to now the most flourishing IP STB, STB's team has grown, and continues to develop. In order to .set-top box of large-scale development, machine cards separate set-top-of-scale development, machine cards separate set-top boxes become the trend. In addition, the dual-mode STB, STB software continues to mature. As digital .home concept of development and promotion, future set-top box might become the family living room technology core control unit, which is the industry known as "Home Gateway" or "Residential Gateway". Apart from packages now existing video transfer functions, the more .is all in the family of smart devices provide an integrated, comprehensive traffic this century to achieve interconnection between devices, and you can give different terminal provides a different personality, "Multi-Play". <br>.