1, What is IPTV
literally speaking, IPTV is the use of IP television programs transmitted ordinary (and therefore sometimes referred to as Web TV), but different industries and organizations, the implications of IPTV but there is a different understanding .
for IPTV why \TV \But these two conditions need to meet, or just need to meet the conditions of the first one to be known as IPTV, there are different understanding. As technology advances, the current TV has been used not only to television display terminals, are now a variety of other services (such as games, stock quotes) display terminal; and television programs has not only watch the TV can also be in the PC and mobile phones and other devices on the watch. Therefore, IPTV reason is called \
for the \CABLE TV business is completely independent in parallel; the traditional telecom industry, by contrast, is a way to achieve \
fact, if the IPTV simply understood as mentioned above, the IP network to simulate the traditional television programs, it is too simplistic and narrow, then IPTV is not promising. IPTV, compared with the traditional TV business, the biggest feature is the ability to personalize the characteristics of on-demand and real-time interactive services can also carry out similar to the traditional telecommunications services and Internet services and other value-added services. Speaking in general terms, IPTV service using IP network (or while taking advantage of IP networks and DVB networks), the media, from television, film and television production companies, media organizations, distance education institutions, and other content providers content through IPTV broadband business application platform (the platform is often not only support TV, also support other business) integration to the user personal computers, set-top box + TV, multimedia handsets (for Mobile IPTV) and other terminals, enabling users to enjoy the rich brought IPTV content for broadband multimedia services.
2, IPTV implementations
Figure 1 simply indicate
IPTV network in the broadcasting and telecommunications implementations, corresponding to the above mentioned \
later when the digital TV, radio and television interactive television network will have a two-way interactive broadcast channels and a single television channel, as shown in Figure 1, interactive TV channels need to interact providers (ie ISP) network communication resources, to interact with TV content providers to realize the basic functions of a number of IPTV. Currently, the broadcasting sector in some parts of the network has spent a lot of two-way transformation of a positive test, trying to be achieved by IPoverDVB of IPTV. However, due to the inherent characteristics of radio and television networks, both from a technical and financial needs huge investment, it is very difficult to achieve, while the inputs and outputs and there will be a considerable gap.
telecommunications industry with an excellent network infrastructure, especially in the integration of business on the Internet has a wealth of operational experience, can give full play to the network, will provide video on demand, highly interactive online games, etc. business. Therefore, in the operating IPTV business has certain favorable conditions, but also on the network transformation is not easy.
Figure 1 IPTV
different implementations
3, IPTV system components
IPTV is a kind of home TV or PC as a display terminal, via the Internet, including TV programs, including the provision of content-rich multimedia services, IPTV is the computing, communications, multimedia and home appliances the integration of new technologies, the key technology is the use of LANkclass = qqx_gjz> computer or \
IPTV actual system components shown in Figure 2.
Figure 2 IPTV system components
(1) program to provide system
The completion of some major programs
digital, so that the original program can be transmitted in the IP network digital programming. Its main function is to broadcast the program coding, conversion and transfer.
(2) content management system
content management system main function is to IPTV programming and content management, content management and its main user management features include: content review, content publishing, content downloads, user management and user authentication billing.
(3) streaming media delivery system
streaming media delivery system includes a device is the center / edge of the distribution of streaming media servers and storage networks.
store distribution network can be composed by multiple servers, load balancing between them to achieve scale through the network, such as the CDN.
streaming media streaming server is to provide the core equipment. Requires a high stability, while supporting multiple concurrent streams can meet and live streaming applications.
(4) access system
end IPTV access systems to provide access to the main function, so that a smooth access to the IP STB to the network, the current common way for xDSL and LAN access method.
(5) IPTV terminal
current IPTV terminal can be divided into three forms, namely, the terminal PC platform, IP-STB platform, terminal and mobile platforms (mobile network) terminal. One, IP-STB IPTV user terminal is the most common consumer devices.
(6) Operation Support System
complete IPTV OSS business acceptance, user management, billing management, revenue management, resource management, ICP management,
belstaff shop, product management, work order management and content access control and other functions, IPTV system to achieve \
4, IPTV content delivery
4.1 programming
IPTV program production system usually consists of content acquisition, content creation (including encoding and transcoding), program management, and other components. Content Acquisition System program source can be camera, television programs, VCD, satellite input signal and so on.
content creation systems provide general program production, recording and broadcasting of live programming and program production and so on. Meanwhile, the content production system can monitor the background automatically live in real time (and recorded) the management information system to automatically use the predefined time live video capture card (recording) a specific channel is broadcast television program; when the program recording is completed, you can automatically uploaded to the streaming media file server, and show the corresponding information stored in the database.
production system supports VCD, DVD, WAV, AVI, MPG, and MP3 files into formats such as ASF, WMV, WMA, RM, MP4 and other streaming media formats, support for a variety of bandwidth, code size stream format, and support equipment to get the video capture card, audio data (TV, video, cameras, etc.) into a streaming media system support files.
4.2 coding techniques
20 century, 90 years, along with video coding technology matures, the International Organization for Standardization (ISO) and International Telecommunication Union (ITU) have launched a series of international standards for video compression coding, has been released are: H.261, H.262, H.263, H.264 and MPEG1, MPEG2, MPEG4 and so on. At present, considered to be more suitable for streaming media systems are mainly used in the standard H.264 and MPEG4.
MPEG-1 used in digital moving images with sound compression coding, rate is 1.5Mbps, general household VCD MPEG-1 is an application; MPEG-2 is an application in professional-grade compression coding standard, for standard digital television and high-definition television in a variety of applications and systems under the layer compression scheme detailed requirements, and its rate from 3Mbps-80Mbps with the Scalability, MPEG-2 Special for digital television broadcast encoding and transmission, have been identified as SDTV and HDTV encoding standard.
to adapt to the flexibility in the transmission of multimedia on the Internet, the International Motion Picture Experts Group (MPEG) 90 in the late 20th century, has released a draft standard MPEG-4, MPEG-4 object-based audio and video Scalable coding techniques, the rate can range from changes in 5Kbps-2Mbps, which combines digital TV, Internet and other interactive areas of graphics and technical functions. It requires efficient coding, emphasized the flexibility of multimedia network communication and interaction.
present, the two ITU-T and ISO International Organization for Standardization Joint Group of Experts JVT video coding for new coding standard H.264 video compression standard, known as AVC (AdvancedVideoCoding) standard, is MPEG-4, Part 10. Not only H.263 and H.264 MPEG-4 than a 50% savings rate, but also has better support for network transmission function. It introduces a mechanism for the encoding of IP packets, is conducive to the packet transmission network, support network, streaming video transmission. H.264 has a strong error resilience characteristics, can be adapted to high packet loss, a serious interference in the wireless channel video transmission. H.264 support for classification of different network resources coded transmission, to obtain a smooth image quality. H.264 can adapt to different network video transmission, the network good affinity. H.264 motion image compression technology standard to rise to a higher stage in the provision of high quality low bandwidth H.264 video transmission is the application of highlights.
AVS is China's own development, a new generation of proprietary encoding. AVS is currently underway in China to develop the specifications of the work, but its goal is not only limited to China, but also as an international standard for external promotion. AVS is replacing MPEG-2 specifications as the goal of efficient encoding, equivalent to H.264 and WindowsMedia9. At present, AVS video mainly for high-definition television, high-density optical storage media applications such as video compression.
addition to the above video encoding technology, the current Internet streaming media formats using more major companies in the United States RealNetworks ReaMedia, Apple's QuickTime and Microsoft's WindowsMedia. The main coding methods include: ASF, nAVI, AVI, DIVx, QuickTime, RealAudio, RealVideo and Real Flash, etc..
4.3 content management system
content management system's main function is to IPTV programming and content management. Through the production of media programs, the manual or automatic storage management system to the streaming media programs, and then in the content management system, organization and content through the channel arrangement, presented to the user through the EPG.
content management system needs to support operations with the IPTV system (BOSS) interface, user access through the portal, the user identity authentication (ie, set-top box access to complete certification), the authorized user services and support set-top box to retrieve content and access media content redirection, and complete billing data collection function, and deductions on the user's account.
content management system needs to monitor the streaming media server or CDN entry conditions are available, when the entry address by more than one server, when the content management system can provide load balancing for these servers.
content management systems need to be copyright management program, in order to prevent users from illegally downloading the virtual player and dissemination of streaming media file; the same time, in order to provide controlled watch streaming media file download services, need to DRM rights management control.
About
the following major content management system technology: EPG menu and digital rights management (DRM).
(1) EPG menu
electronic program guide (EPG) is used to provide users with an easy to use, friendly interface and quick access to a way to see the program, the user can see through the function of one or more channels will soon be on all channels even broadcast on TV.
EPG is consistent with MPEG-2 (13818.1) of the TS into the DVB transport stream standard definition of the business information (ServiceInformation, SI), the integrated receiver decoder set-top box can stream from the TS broadcast the programs to extract a list of program providers and broadcast parameters to the form of visual display to the digital TV users, so users can easily receive, select the digital TV programs.
use of set-top box to watch digital TV programs, users can receive through the EPG is not only an ordinary television, radio, television program or graphics program, but also can view the information of interest, such as: classification by program (such as music programs, sports, movies, etc.) to retrieve programs, program by program providers to retrieve, view the program for some time in the broadcast table and broadcast video networks and other information.
(2) digital rights management (DRM)
digital rights management (DigitalRightsManagement, referred to as DRM) is a related to technical, legal and business at all levels of systems engineering. It is the commercial operation of the digital media provides a means of achieving complete. DRM is to protect multimedia content from unauthorized playback and copying methods. DRM technologies, so copyright owners do not have to spend a lot of time and effort to negotiate with customers to ensure that digital media content can be legally used. DRM will allow content providers are each platform, regardless of the Internet, streaming media and interactive digital television, provides more content, more flexible way of selling the program, while effective protection of intellectual property rights.
DRM technology works is to: establish a digital program authorized center, encoded compressed digital content, using the key (Key) can be encrypted and protected (lock), the encrypted digital programming head store and programs authorized by the KeyID center URL. When the user demand, according to the program head KeyID and URL information to digital program authorized by the authentication center sends the relevant authorization key to decrypt (unlock), programs can not play. Programs need to be protected is encrypted, even if users download save, has not been verified digital program authorized by the Authorization Center can not play, so closely guarded the show's copyright.
5,
belstaff uk, IPTV content store distribution
5.1 distributed storage requirements
IPTV system for distributed storage networks, storage requirements:
● According to the user's geographic location and connection bandwidth, allowing users to connect up to the nearest server, access speed and reduce the user access latency and response time, reduce consumption of network bandwidth;
● global load balancing, improve storage resource utilization, improve performance and quality of distribution services;
● improve resource management of storage and content distribution control, intelligent routing and distribution of the traffic management;
● on user authentication, authentication mechanism, sending the contents are protected, unauthorized users can not distribute;
● high reliability, availability, good scalability and compatibility, to fault-tolerant and easy to expand.
5.2 networking
1) CDN model
IPTV system, the user has a high quality of service requirements, but also to ensure smooth playback. In the wide area network, the client from the user's streaming media server through a very complicated route since it is difficult to ensure a smooth playback. To overcome the complexity of the network route the checks, the IPTV service must be achieved through the edge of the end-user on-demand service, so the content should be distributed from a central server to the edge server, effectively, to achieve the content distributed from the center to the edge server, storage server of such a network system, known as the content delivery network (ContentDeliveryNetwork, CDN).
CDN core idea is to push content from center to edge close to the user, allows the user to obtain the required contents of the nearby, so that will not only improve the performance of the content of user access, and effectively reduce the center of pressure equipment and backbone networks. By CDN, content distribution can be a single center from the original structure into a distributed structure and improve the response speed of user access to the site. Thus, CDN can improve the efficiency of information flow network, technically a comprehensive solution to the network bandwidth is small, user access to large, uneven distribution network problems and improve user access to the site response time.
in a CDN network, including the contents of the cache devices, content switches, content router, CDN content management, and several other important elements. CDN typical composition shown in Figure 3:
Figure 3 CDN network of model diagram
CDN content caching device is to provide point of business is to provide content for the end user devices can cache static Web content and streaming media content, to achieve the edge of the content of communication and storage, so that the final the user's nearest access, so it is deployed in a centralized user access point, complete the content edge of the storage devices are usually used Cache technologies.
users access the contents of the switch is in
focal point and POP points can load balance content caching and access control. In many cases, devices, and content caching in one device. Content switches can be balanced over the contents of the cache device a single point load, which is based on end-user sessions and the content of specific content requests. CDN content switch is one of the optional components, for the larger user access point, content switches can improve the site's usability.
router is responsible for the content of the user's request to the appropriate device scheduling, content routing system is usually achieved through load balancing, load balancing system is the CDN content routing. Its role is to balance the various dynamic load distribution of the contents of the cache site, the request for the user to select the best access to the site, while improving usability. Content routing based on network topology, network latency, server load and rules, policy settings, specify the content of the best sites to request a specific service. Content routers can route based on multiple factors to develop, including the site near the user's degree of content availability, network load, device status. CDN load balancing system is the core of the accuracy and efficiency of load balancing will determine the efficiency and performance of the CDN.
content management system is mainly responsible for the management of the CDN system is optional CDN components, it is the role of content management, such as the injection and distribution of content, content distribution, content of the audit, content, services, and can make the network content distribution and transmission service users or service providers as needed to monitor, manage or control the distribution of web content, equipment status.
However, the current streaming media system based on the construction of the CDN system is mainly designed for the PC, only to a certain extent, meet some of the IPTV business, which IPTV systems and there is a big difference, relying entirely CDN streaming media system to the development of IPTV IPTV is unable to meet the business needs.
First, the current CDN system is different from the video encoding format of digital TV, can not provide broadcast video services. CDN system supports video encoding format is mainly REAL and WMV, the mainstream MPEG2, MPEG4 and H.264 support are very limited. At the same time, live television is the main business of the IPTV, REAL,
belstaff jackets sale, and WMV video encoding format using software compression techniques, time delay 5-10 seconds, it can not support real-time broadcast of high-quality IPTV services business.
Secondly, the traditional CDN designed for PC users to provide VOD programming and accelerate applications such as HTTP browser based, does not consider the provision of live broadcasts.
Finally, the existing CDN system architecture is more simple compared with the IPTV system, usually in a centralized video server architecture, all the programs stored on the server directly, without any transcoding work can be played directly on the Internet. The complexity of its structure can not be required with the IPTV system, compared to CDN system.
2) P2P mode
P2P technology is a PC for different users, without a direct exchange of data relay equipment or services technologies. It broke the traditional Client / Server mode, the peer network, the status of each node are the same, with the dual characteristics of the client and server can also service users and service providers. As the rapid development of P2P technology, the Internet storage model from the current \power back to the user.
P2P network of model changes through a centralized, distributed and hybrid three stages.
centralized P2P model from a central server to share information and feedback is responsible for recording information on the query; each of its peer entities need to share information and be responsible for communications, according to it needs to download additional information on the other entity. Centralized P2P model is all the information available online to provide the information are stored in the client, the server, leaving only the index information, in addition to the server and on other entities, as well as other entities have the ability to interact. Centralized P2P network resources is conducive to the rapid retrieval, and as long as the server capacity is strong enough to be infinitely extended, but the center of the model vulnerable to direct attack.
In a distributed P2P
in and adjacent to the other machine through the connection between peers through the whole network system. Each of the other machines are similar in function, there is no dedicated server, and must rely on their peer distribution network where to find the file and locate the other peer. Distributed P2P solve the problem of resistance to attack, but the lack of quick search and scalability.
hybrid P2P based on a distributed model, the user nodes are classified according to their abilities, so that some of the nodes as a specific task. These nodes are divided into three kinds: the user node, the search node and index node. A node is the node can be both a search index node. Hybrid P2P combination of centralized and distributed the advantages of P2P in the design and processing capabilities have been further optimized.
6, IPTV access systems
with IPTV multicast video, on-demand business in full swing, on a higher access network bandwidth, bandwidth of standard definition IPTV over at least 2Mbps bandwidth, high-definition IPTV bandwidth of at least 6-8Mbps over the bandwidth (MPEG4 video format). If a family has multiple IPTV terminals, when the required bandwidth will be doubled. Taking into account the interaction between various types of network services such as video conferencing, video chat, online games, BBS mapping and other needs, access network upstream bandwidth demand will continue to grow, so IPTV bearer network access bandwidth requirements down the line will be increasingly higher.
Currently, DSLAM equipment is the most common broadband access network infrastructure equipment, IPTV business generally start by DSLAM equipment. DSLAM equipment subject to line quality and the impact of the technology of the following disadvantages: low rates, there is line selection rates; effective transmission distance is short; packet loss rate, QoS is not guaranteed; security is low; limited support for multicast, large Most routers only support IPv4 protocol, does not support multicast. Therefore, IPTV to promote the development of severely limited.
With the rapid development of the network, optical network and optical fiber communication because of its large capacity, high-speed characteristics of the network infrastructure has become the protagonist. At the same time the access network switches support multicast traffic the performance of mature and stable, the price continues to drop. GPON FTTB + LAN is based on Ethernet technology and optical access means. Due to the maturity and simplicity of Ethernet technology, and are used as a cheap and stable high-speed optical fiber transmission medium, these two methods has gradually emerged as the means of IPTV in broadband access and effective way.
GPON provides 1Mbps-1000Mbps symmetrical downstream and upstream bandwidth, the bandwidth of each IPTV users can be dynamically allocated; also access links throughout the whole range of QoS guarantees to support and protect the IPTV the quality of the business; GPON access network coverage up to 20Km, eliminating access to all kinds of copper distance limitations. Domestic carriers have been successfully applied GPON broadband access network technology, proven GPON technology has become a reliable and cost-effective IPTV broadband access technology.
FTTB + LAN broadband access is based on Ethernet technology, using high-speed network to achieve gigabit fiber to the community, combined with the general realization of twisted-pair Fast to the building, Shizhao to the user. FTTB + LAN access technology in the real way is to adopt a two-story media access control technology, direct IP-based services to provide users with the transmission channel. FTTB + LAN as a high-speed broadband access, IPTV broadband business to carry out simple to use, low cost, users do not need to add a dedicated modem, but the shortcomings are obvious, namely, the complexity of cabling inside the building and the use of double wire caused by the limited transmission distance.
FTTH is fiber as a physical medium connecting the user and the operator of a technology. FTTH that can provide high bandwidth access modes, you can easily provide these functions, and to achieve a symmetrical two-way transmission, which is not comparable to other access methods. FTTH can be generally two types of network structure. First, PON passive optical network structure, the second is point to point PtoP structure. FTTH implementations up and down the two lines can reach 100Mbit / s.
family in the future, IPTV and high definition digital television has clear access to high bandwidth is required to achieve 100Mbit / s access will be very necessary, to achieve such a high-bandwidth , other means are difficult to achieve, only FTTX with GPON technology.
7, IPTV terminal system
Currently, telecom IPTV terminal used by the Internet mainly three types: PC + software player, TV + set-top boxes, and mobile streaming media platform for multimedia mobile phones. The \
7.1 PC-based terminal system
PC-based terminal system is in use in the form of Internet video applications, streaming media using the Internet to send a formatted data stream, users can use the computer player, the corresponding visual compression uncompressed audio streaming media file for playback. This form of terminal hardware is relatively simple, only need a PC with Ethernet card, install the appropriate player software can play audio and video programs and Internet browsing. More players, the current application software are Microsoft's WindowsMediaPlayer, Apple's QuickTime and RealNetworks, the Real Player.
PC-based terminal system advantage is simple, low investment, convenient Internet access. Weaknesses of each player above all the software vendors are limited to proprietary file format, general poor. Second is the use of PC monitor to watch TV programs with respect to the small screen and the TV viewing comfort difference. Once again,
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7.2 STB-based end-system
STB terminal system is based on both PC and TV functions, not only has the PC's processing power, but also has the TV viewing experience. Meanwhile, STB is very likely as a home network / media center in the next generation home network. Therefore, IPTV terminal is more optimistic about the \
STB terminal system based on the TV as a monitor and use the dedicated IP-STB to the network audio and video media data reception and decompression, format conversion for the television signal transmission to the TV broadcast.
STB as the CPE to have the features include the following:
● support video on demand, multicast, and Internet browsing, as well as short messaging, video services and online games;
● support the current application of more xDSL or LAN or WLAN and other broadband access. Support TCP / UDP / IP protocol suite, complete interoperability information network transmission, reception and processing IP data and video streaming media data;
● support for decoding of multimedia streams, TV screen displays and digital rights management;
● support content caching, interactive control, access authentication and services and network management capabilities.
7.3 mobile terminal system
reference system for IPTV, mobile terminal it is natural to think of 3G phones, it can handle images, music, video streaming and other multimedia, and using the wireless communication network and the Internet combine to provide network television, video telephony, web browsing, video conferencing, e-commerce and other media services.
8, IPTV and home networking
digital home network is the public network through the home gateway features and applications will be extended to the family, and a wired network or wireless network, connecting all kinds of information terminals (such as home appliances, PC, etc.), provided integrated voice, data, multimedia, control and management functions, to information between terminals within the family and its relationship with the external public network and share the full circulation. Digital home network can be achieved through the following services and applications: with Internet connectivity, and set-top boxes and televisions or computer to achieve VOD, and ASP-based mass storage and a personalized Internet information services and interactive entertainment games and other services. Digital home network business located in three areas: home entertainment, telecommunications and broadcasting services, control and monitoring functions. Figure 4 show a typical home network structure.
Figure 4 a typical home network schematic
home network from the composition can be divided into the following sections: home gateway; all kinds of information terminal devices and smart appliances; smart home networking environment to build, is about the various types of terminals connected digital home and and home gateway connected via wired or wireless means within the family of Internet technology, home networking devices and the information terminal equipment, intelligent appliances, and self-organizing network provides automatic discovery and configuration.
Family Integrated Service Gateway is the home network into contact with the external network bridge the digital home is the key to a variety of services and applications. Home Gateway is a simple, intelligent, standardized, flexible network interface unit the whole family, it can be received from different external network communication signals to pass through the home network signal to a device.
family home gateway can be completed online services, IPTV services, online game business, IP telephony, home video surveillance operations, and remote network management of home control and security services.
home network, including Modem, PC, STB, IAD and other devices that interconnect to form a home network. XDSL lines from IPTV video services through the home network to the STB, the STB decoding video signals to achieve on a TV show. STB can be used as an extension of the home network, providing digital entertainment, communications, intelligent home network solution for sharing, integration, broadband networks will be moved into the living room from the user's study.
broadband business to the next few years the development of home users, IPTV business will likely become the digital home,
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9, IPTV and Digital TV
Table 1 IPTV and digital TV comparison chart
IPTV and digital television,
outlet belstaff, both the similarities and differences between them. IPTV and Digital TV on the example shown in Table 1. IPTV can be seen from Table 1 is based on broadband telecommunications network to transmit television in the form, not only allows users to watch more TV programs on-demand programs can also function to extend other value-added telecom services.
Linear Mode
