Sunday, April 3, 2011
Weak current College】 【understanding IP networks for IPTV Terminal and set-top box technology】.
<br> Understanding IP networks for IPTV Terminal and set-top box technology <br> As a support of interactive applications, IP set-top box will not only support IPTV business, also in a broader role to play in the area of interactive multimedia .. Broadband network and access technology development, expanding the application range of broadband services. Popular TV programmes are not only known by Cable to the TV, you can also make use of broadband IP networks use PC, mobile phone or TV set-top box + .way of watching TV, this is the power of IPTV. IPTV emergence of the concept of cause two major television and telecommunication industry strongly dispute, the television industry that IPTV is a complement to the digital television should be based on the technical implementation, IPoverDVB telecom .industry considered that IPTV is on an IP network, with a value-added business TVoverIP. As the industry achieve different IPTV technology allows rendering business user terminal was different. Digital television is to Cable and satellite television signal, the user terminal is STB-C .+ TV or STB-S + TV; telecommunications users main IPTV terminal types: 3 PC + software player, TV set + set top box, mobile streaming platform for multimedia mobile phones. This article primarily describes for IP network of IPTV Terminal and set- .top box technology. I. IPTV terminal type 1. Terminal based on PC systems based on PC Terminal system followed the application of Internet video, use of Internet streaming media technology transfer a format of the data flow, users can use on your computer corresponding to .the player on the compression of audio and video streaming media file after decompression. This form of Terminal hardware is relatively simple, only need 1 computers with the Ethernet card in the PC to install the appropriate player software can play audio and video programs and Internet browser .. Current applications more player software is Microsoft's WindowsMediaPlayer, Apple's QuickTime and RealPlayer by RealNetworks company. PC based simple terminal system advantages, investment is small, convenient Internet access. Shortcomings in the first, each player software are limited to private firms, the versatility of .file format. Second is the use of PC monitor to watch television programmes relative to the TV set to watch screen small and comfort. Once again, is not to use the computer for people who cannot access this service. Therefore in the light of the above .analysis, the use of the PC as IPTV end system can only be temporary or not suitable for display on the TV using the site, and not suitable for large range extension. <br> 2. based on the STB's Terminal system Terminal system based STB .is to combine the functionality of the PC and television sets, both PC's processing power, but also has TV viewing. At the same time, the STB is most likely as a home network / media center appears on the next-generation home network. As .a result, IPTV Terminal looking TV + set top box, IPTV service terminal. Terminal system based STB to TV as a monitor, use a dedicated IP-STB on network audio and video media data reception and extract, convert to TV signal format to play .on TV. STB as client devices to have the features include the following aspects: support to video on demand, multicast and Internet browsing as well as text messages, Visual business and network game; support for the current application more LAN, xDSL or WLAN and .broadband access, support for TCP / UDP / IP protocol family, complete interoperability information for network transmission, reception and processing of IP data and video streaming media data; support for the multimedia stream's decoding capabilities, TV screen displays and digital rights management; support content .caching, interactive control, access authentication, and business and network management features. 3. the mobile terminal system mentioned for IPTV, mobile terminal system people will naturally think of 3 g mobile phone, it can handle images, music, video and other multimedia, .and use of wireless communication networks and the Internet combined with Internet TV, video phone, Web browsing, videoconferencing, e-commerce, and other media services. <br> IPTV, mobile terminal in application there are still many problems to be solved. First ., in viewing, no matter what technology is used to play the images, their speed will be subject to the constraints of the network speed, it is difficult to achieve the same as TV real-time transmission of smoothing effect. Although the use of mobile .phone to watch Internet video effect is also good, because now mobile video business is also limited to a small number of high-end users. With IPTV business development and universal access, user a rise in the amount of network bandwidth and processing power of the .mobile phone can become a bottleneck. Play current mobile power technology cannot and IPTV mobile terminal's powerful features, mobile phone standby time is too short, and IPTV business a film at least 90 minutes, the consumption of electricity is very impressive to watch a short program .is still available, but would like to read a Minister tablets ever replace the battery is needed, this undoubtedly for IPTV business is a big obstacle. 4.STB + TV will become the mainstream of IPTV Business IPTV business can consist of a terminal for many .types of terminals, but the most practical and can be accepted by the majority of consumers should be to set-top box + TV combo. First, this approach maintains user's leisure habits, from the perspective of human biology, the most comfortable viewing positions are .backward 30 degrees, the computer's posture is leaning 30 degrees, traditional Internet video PC user is used as a display terminal operating computers pose to keep leaning forward, therefore long operations are very tired, and susceptible to diseases such as cervical disease PERIARTHRITIS. Second is .the use of STB + TV not only keep the TV programme you can also use Internet content from the library moved to the living room, so does the computer will be able to surf the Internet, using Internet to send and receive e-mail, chat .. Will broadband users from Internet family extends to non-addicted, broadband entertainment market from 2200 million broadband users, 87 million Internet users, Extended to 1 billion TV viewers. In short, whatever is the use of IPTV STB terminals + TV or PC, .should have the following features: communication interface, analog output, peripheral control, video decoding and embedded real-time operating system, through a terminal device users can conduct business requests, video / audio data reception and network services. <br> Second, set .-top boxes Overview 1. What is the STB set-top box set-top boxes (Set-top-box) as the name suggests is placed in the box on the TV, digital TV. It is a digital television signal into analog conversion .equipment. In digital TV application mainly according to the transmission network is different there are three types of set-top box for cable television networks of digital TV set-top box STB-C, used for satellite TV network's digital TV set-top box STB .-S and used for terrestrial broadcast digital TV set-top box STB-T, they met the standard for digital television, DVB-S and DVB-T DVB-C. Based on Internet Protocol (IP), set-top box is the .latest thing. With the development of IPTV, making this product gained great momentum. Because IP set-top box can not only provide the majority of cable or satellite set-top box of the same features, but you can also use the current low- .cost Internet and IP-based network facilities. In addition, based on two-way IP networks can instinctively supports a variety of applications and interactive services. 2. set-top box development STB set-top box (Set-Top-Box) originated .in the early 1990s, when in Europe and the United States as the charge cable TV fees of an important means. Cable TV operators in each user's installation of a key before the TV magazine, only paid a fee by the user can decrypt the TV signal ., the normal TV. This is the first set-top box. Mid-1990s, the rapid development of Internet in the world and growing popularity, people use TV Internet raises, and began to study Internet set-top box. At that time, .computers and network equipment manufacturers expect Internet set-top box can constitute a new household appliances. However, because the technology is not mature, and ultimately is not significant. At the end of the 20th century, in Europe and the United States began to broadcast .digital television (DTV) and high definition digital television (HDTV), and again was the highlight of the set-top box. When the set-top box's main role is to digital television signals to analog conversion, to ensure regular analog TV set you .can watch digital TV or digital high definition TV. The appearance of the IPTV set-top box and the further development, set-top boxes are not only used for digital television, but also as an IP network and TV bridges that broadband network and varied .programme content via set-top box on a TV show, for the majority of ordinary TV viewers a new digital life new feel. <br> 3.IP STB features IP set-top box's basic function is to receive digital television, with all the .radio, on-demand and interactive multimedia applications function, also includes the following features. (1) the electronic program guide (EPG): EPG can provide a friendly interface, easy operation, you can quickly access programs. The user can see all channel .EPG feature in the near future will play on the TV and select the available to users on demand content index, active retrieve on demand. (2) interactive applications: provides the user with video-on-demand, multicast and interactive games. Through the .interactive features of the application, in order to operate home DVD as fast forward, rewind, pause; in multicast, you can quickly switch TV channels. Through the interactive features of the application, it can also be used for interactive games. (3) .online software upgrade: using the set-top box middleware plug-in provides the ability to probe set-top boxes, online installation and application software updates of set-top box. Set-top box to identify the software version number, the version is .not at the same time receive the software, and saved in the memory of the software to be updated. (4) Internet browsing and e-mail: users can set-top box built-in Internet browser on the Internet, send e-mail .messages. 4.IP set-top box type currently used in IPTV Business basic set-top box has two types: standard and enhanced. Basic set-top box with on-demand features, radio features, EPG browsing, Web browsing and games, .and other business skills; enhanced set-top box is on the basis of the basic type of increasing personal video storage (PVR), online games, video communication, FLASH, and other business capabilities. IPTV set-top box access to broadband networks may .use the FTTB + LAN access mode, xDSL access, WLAN access and other broadband access modes. IPTV set-top box hardware platforms there are three approaches: ASIC-based STB, based on the DSP of the STB, the central processing unit CPU based .STB. <br> With the emergence of IPTV business, many set-top box manufacturers and telecom equipment manufacturers to actively study for IPTV set-top box, but most of the current development of the product is only applicable to the respective IPTV business system .. This system is bound to a set-top box versatility is very poor, and other Exchange IPTV system simply cannot. Its results will cause the business operators in equipment selection and cost control of passive, if things go on like this will hinder the development .of IPTV. Solution to this problem is to develop technical standards for IPTV set-top box, from the business functionality, performance and safety of uniform specification. <br> III. IP set-top box technology 1. video decoding and playback of video .encoding technology great variety, as broadband access conditions, suitable for IPTV business video and audio codec technology mainly MPEG-4, H.264 and WMV9, different IPTV service platform using encoding technology is different. MPEG-4: "ISO/IEC14496-information .technology-Generic coding of audio-visual objects "standard, which is directed at the low rate of video and audio encoding andInteractive play development of algorithms and tools for its distinguishing feature is based on the content encoding. Greater emphasis on multimedia systems of interactivity, .interoperability and flexibility. MPFG-4 standard Visual audio codec's contribution can be divided into the following three categories. (1) content-based interactivity: content-based multimedia data access tool, based on the content of the stream manipulation and editing; natural and .synthetic data mixed encoding; enhanced time domain random access. (2) high compression rate: increase coding efficiency; multiple concurrent streams encoding. (3) flexible access: error-prone environment against wrong; the scale variability based on content. H.264 .: is the International Organization for Standardization (ISO) and the International Telecommunication Union (ITU) jointly proposed the following MPEG-4 after the new generation digital video compression format, which preserves the previous compression technology advantages and essence and other compression technologies can not be .compared. <br> (1) low-bit-stream: and MPEG-2 and MPEG-4ASP etc. compression technology compared to the same image quality, the use of H.264 technology compressed data volume is only 1 / 8 MPEG- .2, MPEG-4 1 / 3. Obviously, the use of H.264 compression technology will greatly save the user's download time and data traffic fees. (2) high quality images: H.264 provides continuous, smooth high quality images (DVD .quality). (3) fault-tolerant capability: H.264 provides solutions in unstable network environment vulnerable to the loss of necessary tools, such as error. (4) network adaptability: H.264 provides network adaptation layer, enables H.264 .files can be easily transferred across the network. AC-1: is Microsoft's video coding standard, is submitted to the SMPTE WMV9 introduced after the name of the coding standard. SMPTE (SocietyofMotionPictureandTelevisionEngineers, United States film and television engineers) is the National Standards Institute .United States (ANSI) accredited, internationally renowned video, television and film industry standards development organizations, SMPTE in formulating and explore private specification with extensive experience, September 2003, SMPTE receive WMV-9 used by compression technology specification as a standard video codec format. .To adapt to different IPTV service platform provided by the encoding method that requires IP set-top box should have the support of more than one capacity of decoding. You can support more than 1.2Mbit / s MPEG-4 stream decode, or support for H ..264 video decoding, and have upgraded from MPEG-4 to H.264. Set-top box as a network and communication between users, not only need to receive IP-STB network video, while the video to the TV (or monitor) ., thus to both encode and playback capabilities. 2. graphics and images displayed on the TV system in China technology selection North America PAL, IP set-top box using the TV as a monitor, the player must support 720 * 576 PAL SD resolution image .decoding. Meet the requirements, support for aspect ratio ITU-RBT601 4: 3 or 16: 9 video decoding. In order to meet the needs of different IPTV platforms, IP set-top box should support multiple display resolution and format of graphic display, .display graphics require support definition for 720x576, 352x 288,448 x 336,640 x 480,800 x 600 graphics display, each pixel support at least 16-bit color; can automatically adjust the input and output graphics. <br> As for the use of television for Internet browsing ., as a general Web pages are displayed in a PC, use your TV as a display requires appropriate display technology. Television and computer monitors, CRT displays is a mature technology, but uses a low-resolution TV display text, especially in less than 24 .× 24 in small print, the issue becomes complicated. The TV picture tube is the big pitch of low resolution, only suitable for displaying 720 × 576 or 640 × 480 image, its deflection system is fixed to 525 lines 60Hz or 625 lines 50Hz design .. The Internet is to comply with the VESA format, obviously, the TV displays the system will not be able to meet so many formats. In addition, television has a low frame rate in interlaced mode, when you display a graphic and text, blinking .background luminance signal presence, horizontal line exists between lines. If the progressive scan computer graphics to television, the horizontal edge will only appear in the odd field or ouchang, display time close to the human eye Visual interning, produces powerful edge flashing phenomenon, and .thus to TV on the Internet, it is necessary to remedy the defects of a TV show. 3. middleware middleware technology in the computer systems have a wide range of applications, now also began to set-top box design software. Middleware is located in .the STB's real-time operating system and applications, the connection between the two parts of the software. Middleware makes set-top-box application and low-level hardware and network parts separation, application development and hardware low-level and platform-independent; .provides a common application programming interface (API) that enables applications to reduce the difficulty of developing, improving efficiency. In the development of set-top box in the upper applications often have to face the following problems: real-time multitasking operating system, hardware .platform details, complicated principle of industry standards, complexity of the user interface as well as practical functions such as cross-industry challenges. In order to solve the above problem, middleware technology came into being, and becoming the core technology for digital TV, we .previously mentioned open service platform. Middleware is the digital TV receiver applications and operating systems, hardware platforms embedded a middle tier that defines a set of more complete, standard application interfaces that let applications independent of the operating system and hardware platform, the development of the .application becomes more simplified, the product of openness and more portable. It is typically used by the Java virtual machine, A Web browser, image and multimedia modules, etc. Open service platform is characterized by product development and production to a business platform as a .basis for open service platform for each link provides independent operating modes, each part has its own profit, can produce more than one supplier. Only open service platform to ensure that set-top box scalability to ensure effective recovery of the investment. <br> .4. embedded system applications embedded system is a computer technology, communications technology, semiconductor technology, microelectronics technology, voice, image data transmission and processing technology, sensor technology and even specific application object based on the combination of products, is a technology-intensive, .investment strength of large, highly distributed innovative knowledge-intensive system, reflect the most advanced level of the new technology. In General, the embedded chip for embedded systems, embedded software, embedded operating systems and embedded systems development tools 4 parts. Embedded chip including .embedded microprocessors, embedded microcontroller and embedded digital signal processor and embedded SOC, with RISC computer technology and the rapid development of micro-electronics technology, embedded chipset features more and more strong, more and more small volume. Embedded real-time operating system is relative .to the desktop computer operating system, it is not installed on the hard disk, the system structure is compact, functional relatively simple, resources open-smaller, easy to cure in storage. The role of embedded operating systems and PC DOS and Windows, similar .to the user through it for man-machine conversation, complete the user's specified release. Specifies receive various ways such as keyboards, mice, voice, touch screen, infrared remote control, etc. Embedded CPU is at the core of the IP set-top .box, which you want to manage, set-top boxes of all interfaces, including the network side of the interface, infrared interface as well as each kind of extension interface, to handle the IP protocol stack, control and scheduling of all underlying device driver .. It and media processor or control decoding chip received audio and video streams decoding conversion, video, audio and data left, by controlling the digital / analog converter into TV signal output to TV shows. General IP set-top box dedicated embedded CPU most integrated .media handling capabilities, enhanced set-top box is also available with dual CPU mode. Embedded operating system platform that features include network management, display management, smart card management (IC cards and Smart cards), Teletext decoding, decoding of data, video signals .and down transformation as well as features such as interactive control. In order to achieve these capabilities, embedded CPU must extend a new function, increasing processing speed, in order to adapt to future business development requirements. IV. concluding remarks future telecommunications services would be .to interactive multimedia application-oriented business. As a support of interactive applications, IP set-top box will not only support IPTV business, also in a broader role to play in the area of interactive multimedia. Therefore, in the development of IP set- .top boxes, you need to have a forward-looking, advanced design. Give full play to the role of middleware, so that the STB such devices have extensions and smooth upgrade capability, this product will have a strong vitality. <br>.