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<!--'''Internet Protocol television''' ('''IPTV''') is a system through which [[digital television]] service is delivered using the architecture and networking methods of the [[Internet Protocol Suite]] over a packet-switched network infrastructure, e.g., the [[Internet]] and [[broadband]] Internet access networks, instead of being delivered through traditional [[radio frequency]] broadcast, [[satellite]] signal, and [[cable television]] (CATV) formats. See [[Internet television]].
 
'''IPTV''' (Angla akronimo por : Internet Protocol Television ('''IPTV''')) estas sistemo tra kiu servo de [[cifereca televido]] estas liverata uzante arkitekturon kaj retajn metodojn de la internet-protokola vico sur pakkomuta reta infrastrukturo kun regata servkvalito, t.e., la [[Interneto|Internet]]a kaj [[larĝbenda]] interneta alirretoj, anstataŭ esti liverata tra tradicia radifrekvenca dissendo, satelita signalo, kaj [[kabla televido]] (CATV) formatoj. Vidu [[Interneta televido]].
IPTV services may be classified into three main groups: live television, time-shifted programming, and content (or video) on demand. It is distinguished from general Internet-based or web-based multimedia services by its on-going standardization process (e.g., [[ETSI]]) and preferential deployment scenarios in subscriber-based telecommunications networks with high-speed access channels into end-user premises via [[set-top box]]es or other [[customer-premises equipment]].
 
==Definition Karakterizo ==
Historically, many different definitions of IPTV have appeared, including elementary streams over IP networks, transport streams over IP networks and a number of proprietary systems. Although (in Mid 2007) it is premature to say that there is a full consensus of exactly what IPTV should mean, there is no doubt that the most widely used definition today for consumer IPTV is for single or multiple program transport streams (MPTS) which are sourced by the same network operator that owns or directly controls the "last mile" to the consumer's premises {{Citation needed|date=April 2008}}. This control over delivery enables a guaranteed [[quality of service]] (QoS), and also allows the service provider to offer an enhanced user experience such as better program guide, interactive services etc.
 
Sub la termino IPTV, ariĝas la [[rekta televido]], la [[video laŭ peto]] (angle: ''Video on Demand'' aŭ (VoD)) kaj la [[postdissenda televido]] (angle [[Catch-up TV]]). La livermetodoj estas diversaj. La rekta televido uzas [[Multicast|IP multicast]] solvon, kio ebligas sendi la signalon nur unufoje al pluraj personoj. La VoD kaj la postdissenda televido uzas [[Unicast|IP unicast]]-an solvon (Tiom da fluoj kiom da celoj). Ĝi uzas la saman infrastrukturon, kiel la interneta aliro, sed kun rezervita flurapido.
In commercial environments IPTV is widely deployed for distribution of live TV, video playout channels and [[Video on Demand]] (VOD) material across [[LAN]] or [[WAN]] IP network infrastructures, with a controlled QoS.
En Francio, ofte ĝi estas en la internetabona oferto [[altrapida]]. La [[internetaliraj provizistoj]] parolas pri oferto ''[[Triple play (télécommunications)|triopa]]'' (Interneto, telefonio, televido).
 
== Historio ==
The official definition approved by the International Telecommunication Union focus group on IPTV (ITU-T FG IPTV) is as follows:<br />
''"IPTV is defined as multimedia services such as television/video/audio/text/graphics/data delivered over IP based networks managed to provide the required level of quality of service and experience, security, interactivity and reliability."''
 
* En 1992, Steve Caser, por solvi la problemon de la limigita nombro da [[routeur]]j kapablaj je IP-multikasto kaj la manko de adresoj en IPV4 proponas virtualan reton nomatan [[MBone]].
==History==
* En 1995, la kompanio "Precept Software" ekvendis la produkton IP/TV. La kompanio aĉetita en 1995 de [[Cisco Systems|Cisco]] fariĝas marko.
In 1994, [[American Broadcasting Company|ABC]]'s [[World News Now]] was the first [[television program|television show]] to be broadcast over the Internet, using the [[CU-SeeMe]] [[videoconferencing]] software.<ref>[http://economictimes.indiatimes.com/articleshow/msid-589392,prtpage-1.cms What is IP television?]</ref>
* En Septembro 1999, Kingston Communications, regiona angla operatoro, lanĉas la oferton KIT (Kingston Interactive Television) enhavantan servon de IPTV kaj de Vod sur ADSL.
 
== Avantaĝoj/malavantaĝoj ==
The term IPTV first appeared in 1995 with the founding of [[Precept Software]] by [[Judith Estrin]] and Bill Carrico. Precept designed and built an Internet video product named ''IP/TV''. IP/TV was an [[MBONE]] compatible Windows and Unix-based application that moved single and multi-source audio/video traffic, ranging from low to DVD quality, using both [[unicast]] and [[IP multicast]] [[Real-time Transport Protocol]] (RTP) and [[Real time control protocol]] (RTCP). The software was written primarily by [[Steve Casner]], [[Karl Auerbach]], and Cha Chee Kuan. Precept was acquired by Cisco Systems in 1998.<ref>[http://www.cisco.com/warp/public/750/acquire.html Cisco - Summary of Acquisitions]</ref> Cisco retains the IP/TV trademark.
 
La IP-a teknologio ebligas la uzon de la interfaco far pluraj internetaj aplikoj, [[Voĉo sur IP-a reto|VOIP]]). Plie, la [[kodilo]]j, pli kaj pli efikaj ([[MPEG-2]], [[MPEG-4]] kaj [[Video Codec 1|VC-1]]) ebligas ŝpari la [[pasbendo]]n.
[[Internet radio]] company [[Broadcast.com|AudioNet]] started the first continuous [[live television|live]] [[webcast]]s with content from [[WFAA-TV]] in January, 1998 and [[KCTU-LP]] on January 10, 1998.<ref>[http://wichita.bizjournals.com/wichita/stories/1998/02/16/focus1.html KCTU-TV earns a place in television, Internet history - Wichita Business Journal:<!-- Bot generated title -->]</ref>
 
[[Kingston Communications]], a regional telecommunications operator in UK, launched KIT (Kingston Interactive Television), an IPTV over [[DSL]] broadband interactive TV service in September 1999 after conducting various TV and [[Video on demand|VoD]] trials. The operator added additional [[Video on demand|VoD]] service in October 2001 with Yes TV, a provider VoD content. Kingston was one of the first companies in the world to introduce IPTV and IP [[Video on demand|VoD]] over [[ADSL]].
<ref>[http://www.iptvxl.com/iptv/history/ History of IPTV]</ref>
 
In 2003, [[Total Access Networks Inc]] launched its IPTV service, comprising of 100 free IPTV stations world wide. The service has been used in over 100 countries world wide, and has channels in 26 languages.{{Citation needed|date=June 2009}}
 
{{Portalo|televido|Telekomunikoj}}
In 2005, [[Bredbandsbolaget]] launched its IPTV service as the first service provider in [[Sweden]]. As of January 2009, they are not the biggest supplier any longer; [[Telia]] who launched their service later has now more customers.<ref>[http://www.idg.se/2.1085/1.203998/bredbandsbolaget-rustar-pa-ip-tv "Bredbandsbolaget is mobilizing for IP TV" (Swedish)]</ref>
 
[[Kategorio:Video sur IP-a reto]]
In 2006, [[AT&T]] launched its [[U-Verse]] IPTV service in the [[United States]], comprising a national head end and regional video-serving offices. AT&T offered over 300 channels in 11 cities with more to be added in 2007 and beyond. On March 2009, AT&T announced that U-verse had expanded to 100 or more High Definition channels in every U-Verse TV market.<ref>[http://www.att.com/gen/press-room?pid=4800&cdvn=news&newsarticleid=26580 AT&T U-verse TV Lineup Expands to 100 or More High Definition Channels in Every U-Verse TV Market]</ref> While using IP protocols, AT&T has built a private IP network exclusively for video transport.
[[Kategorio:Tekniko de televido|Iptv]]
 
[[Kategorio:Cifereca Televido]]
===Future===
In the past, this technology has been restricted by low broadband penetration and by the relatively high cost of installing wiring capable of transporting IPTV content reliably in the customer's home. In the coming years, however, residential IPTV is expected to grow at a brisk pace as broadband was available to more than 200 million households worldwide in the year 2005, projected to grow to 400 million by the year 2010.<ref>[http://www.gartner.com/it/page.jsp?id=501276 Gartner - 2007 PRESS RELEASES]</ref> Many of the world's major telecommunications providers are exploring IPTV as a new revenue opportunity from their existing markets and as a defensive measure against encroachment from more conventional Cable Television services.
 
Also, there is a growing number of IPTV installations within schools, universities, corporations and local institutions.<ref>[http://www.iptv-industry.com/ar/19d.htm Internet TV: Communicating in the 21st Century]</ref>
 
In December 2009, the FCC began looking into using set-top boxes to make TVs with [[Multichannel video programming distributor|cable or similar services]] into [[broadband]] video players. FCC Media Bureau Chief Bill Lake had said earlier that TV and the Internet would soon be the same, but only 75 percent of homes had computers, while 99 percent had TV. A [[Nielsen Company|Nielsen]] survey said 99 percent of video viewing was done on TV.<ref>{{cite news|url=http://www.broadcastingcable.com/article/439909-Broadcasters_Squeezed_by_Convergence_Push.php?rssid=20068&q=digital+tv|title=Broadcasters Squeezed by Convergence Push|first=John|last=Eggerton|work=[[Broadcasting & Cable]]|date=2009-12-14|accessdate=2009-12-17}}</ref>
 
==Markets==
[[Image:IPTV-Countries.svg|thumb|400px|right|Map of IPTV countries of the world.
{{legend|#5b92e5|Countries where IPTV is available in at least some parts of the country}}]]
 
While all major western countries and most developed economies have IPTV deployments, the world's leading markets for IPTV for now are [[Germany]] (by [[Deutsche Telekom]]) [[France]] (led by [[Iliad (company)|Free]], then [[Orange (brand)|Orange]], then [[Neuf Cegetel]]; total of over 4 million subscriptions), [[South Korea]] (1.8 million subscriptions), [[United States]] (by [[AT&T]]), [[Hong Kong]], [[Japan]], [[Italy]], [[Spain]], [[Belgium]], [[Austria]], [[China]], [[Singapore]], [[Switzerland]] and [[Portugal]]. Services have also launched in [[Bosnia and Herzegovina]], [[Croatia]], [[Republic of Macedonia|Macedonia]], [[Montenegro]], [[Poland]], [[Romania]], [[Serbia]], [[Slovenia]]<ref>http://www.bhtelecom.ba/portalnovost+M5c30c4559cc.html</ref>, [[The Netherlands]]<ref>http://www.kpn.com/tv.htm</ref>, [[Denmark]], [[Finland]], [[Estonia]], [[Hungary]]<ref>http://www.t-home.hu/lakossagi/tv/iptv</ref><ref>http://www.invitv.hu</ref>, [[Norway]], [[Sweden]] and [[Iceland]]. The [[United Kingdom]] launched IPTV early and after a slow initial growth, in February 2009 [[BT Group|BT]] announced that it had reached 398,000 subscribers to its [[BT Vision]] service.<ref>[http://www.iptv-news.com/iptv_news/february_09/bt_vision_passes_398k_subs_in_4q08 BT Vision passes 398k subs in 4Q08]</ref> [[Claro (mobile phone network)|Claro]] has launched their own IPTV service called "Claro TV". This service is available in several countries in which they operate, such as [[Dominican Republic]], [[El Salvador]], [[Guatemala]], [[Honduras]], [[Nicaragua]]. IPTV is just beginning to grow in Central and Eastern Europe and Latin America, and now it is growing in South Asian countries such as [[Sri Lanka]], [[Pakistan]] and especially [[India]].<ref>[http://www.broadbandtvnews.com/?p=4685 "Salad days,"] Chris Dziadul, ''Broadband TV News,'' May 2, 2008</ref> but significant plans exist in countries such as [[Russia]]. [[Kazakhstan]] introduced<ref>[http://www.iptv-industry.com/ar/23i.htm Delivering IPTV System to Kazakhtelecom] Article from the IPTV industrial portal</ref> its own IPTV services by Alacast and national provider Kazakhtelecom<ref>[http://www.telecom.kz/index.php?actn=home&uin=1240830886&lang=eng iD TV services for broadband subscribers in Kazakhstan] JSC Kazakhtelecom - iD TV service for Home users</ref> under the "iD TV" brand in two major cities Astana and Almaty in 2009.
 
The first IPTV service to launch on the Chinese mainland sells under the "BesTV" brand and is currently available in the cities of Shanghai and Harbin.<ref>[http://www.indiantelevision.com/headlines/y2k8/may/may2.php "BabyFirst launches on BesTV in China,"] ''Indiantelevision.com Team,'' May 2, 2008.</ref> In India IPTV was launched by Airtel and the government service provider MTNL and BSNL. In Pakistan IPTV was launched by PTCL, brand name Smart TV. In Malaysia, [[Hypp.TV]] will be launched as [[Telekom Malaysia|TM]]'s IPTV service.
 
==Distinction of IPTV from Internet TV==
A telco IPTV service is usually delivered over a complex and investment heavy [[Walled_garden_(technology)|walled garden network]], which is carefully engineered to ensure bandwidth efficient delivery of vast amounts of multicast video traffic. The higher network quality also enables easy delivery of high quality SD or HD TV content to subscribers’ homes. This makes IPTV by default the preferred delivery platform for premium content. However, the investment for a telco to build an end-to-end IPTV service can be substantial.{{Or|date=July 2009}}
 
By contrast "Internet TV" generally refers to transport streams sent over IP networks (normally the Internet) from outside the network that connects to the users premises. An Internet TV provider has no control over the final delivery and so broadcasts on a "best effort" basis. Elementary streams over IP networks and proprietary variants as used by websites such as YouTube are now rarely considered to be IPTV services.{{Or|date=July 2009}}
 
Compared to telco IPTV, Internet TV is a quick-to-market and relatively low investment service. Internet TV rides on existing infrastructure including broadband, ADSL, Wi-Fi, cable and satellite which makes it a valuable tool for a wide variety of service providers and content owners looking for new revenue streams. However, due to the fact that IPTV is always delivered over low cost IP [[Set-top box|STB]]s, which have limited computing power, the capability for IPTV operators to provide diverse multimedia services is limited. This is where Internet TV has an advantage as it is delivered to a subscriber's (generally) powerful PC.
 
The relative ease of establishing an Internet TV service seems at first a threat to telco IPTV operators’ multimillion dollar investment, but both services do not necessarily compete for the same customers and there are some synergies between the two such as a common technology platform in the form of web-based technologies for content storage and delivery.
 
Broadcast IPTV has two major architecture forms: free and fee based. As of June 2006, there are over 1,300 free IPTV sources available.<ref>[http://www.crtv.net/hispeed_cable/iptv.html IPTV - Another Viewing Choice!]</ref> This sector is growing rapidly and major television broadcasters worldwide are transmitting their broadcast signal over the Internet. These free IPTV sources require only an Internet connection and an Internet enabled device such as a personal computer, HDTV connected to a computer or even a 3G cell/mobile phone to watch the IPTV content. Various Web portals offer access to these free IPTV sources. Some cite the ad-sponsored availability of TV series such as ''[[Lost (TV series)|Lost]]'' as indicators that IPTV will become more prevalent.
 
Because IPTV uses standard networking protocols, it promises lower costs for operators and lower prices for users. Using [[set-top box]]es with broadband Internet connections, video can be streamed to households more efficiently than current coaxial cable. Home networks currently use technology from the [[Multimedia over Coax Alliance]], [[HomePlug Powerline Alliance]] or [[Home Phoneline Networking Alliance]] to deliver IPTV content to any set-top box in a home, without having to install new [[Ethernet]] wires and without relying on technologies like [[802.11]], which are not optimized for reliable delivery of video streams. ISPs are upgrading their networks to bring higher speeds and to allow multiple High Definition TV channels.
 
IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software (much like a cable or DSS box) that can handle viewer requests to access to many available media sources.
 
Local IPTV, as used by businesses for [[audio visual]] AV distribution on their company
networks is typically based on a mixture of:
# Conventional TV reception equipment and IPTV [[encoders]]
# IPTV Gateways that take broadcast MPEG channels and IP wrap them to create [[multicast]] streams.
 
==Architecture of IPTV==
===Architecture of a Video Server Network===
Depending on the network architecture of the Service Provider, there are two main types of Video Server architectures that can be considered for IPTV deployment, Centralized, and Distributed.
 
The Centralized Architecture model is a relatively simple and easy to manage solution. For example, as all contents are stored in Centralized servers, it does not require a comprehensive content distribution system. Centralized Architecture is generally good for a network that provides relatively small VOD service deployment, has adequate core and edge bandwidth and has an efficient Content Delivery Network (CDN).
 
A Distributed Architecture is just as scalable as the Centralized model, however it has bandwidth usage advantages and inherent system management features that are essential for managing a larger server network. Operators who plan to deploy a relatively large system should therefore consider implementing a Distributed Architecture model right from the start. Distributed Architecture requires intelligent and sophisticated content distribution technologies to augment effective delivery of multimedia contents over service provider's network.<ref>[http://www.inwf.com/pubs/print/aroc58_toc.html Distributed Architecture vsCentralized Architecture for IP VoD, Annual Review of Communications, Vol. 58]</ref>
 
===Home Networks for IPTV distribution===
{{ITU-T Home networking Recommendations}}
In many cases, the Residential Gateway that provides connectivity with the Broadband Access network is not located in close proximity to the IPTV Set-Top Box. This scenario becomes very common as service providers start to offer service packages with multiple Set-Top Boxes per subscriber.
 
Traditional home networking technologies such as [[Ethernet]] and [[802.11]] do not provide a good solution to provide connectivity between the Gateway and each Set-Top Box. Most homes today are not wired with Ethernet cable in every room, and installing new Ethernet cables is expensive for service providers and undesirable for consumers. Wireless technologies like 802.11 are optimized for data transmission, but they usually don't provide the [[Quality of Service]] required by IPTV applications.
 
Networking technologies that take advantage of existing home wiring (such as power lines,<ref>[http://www.telecoms-mag.com/article.asp?HH_ID=AR_4934 HomePlug Alliance keeps plugging away]</ref><ref>[http://blog.ds2.es/ds2blog/2009/04/iptv-distribution-using-powerline-networks.html IPTV distribution using DS2 powerline networks]</ref> phone lines or coaxial cables<ref>[http://www.reuters.com/article/pressRelease/idUS171465+17-Feb-2009+GNW20090217 20 Million MoCA Nodes Have Been Shipped]</ref><ref>[http://www.lightreading.com/document.asp?doc_id=118351 LightReading: Why AT&T Likes HomePNA]</ref>) have become a popular solution for this problem, although fragmentation in the wired home networking market has limited somewhat the growth in this market.<ref>[http://www.smartgridtoday.com/public/873.cfm Could MoCA/HomePlug win
in-home networking wars?]</ref><ref>[http://homegridforum.typepad.com/homegrid_forum/2008/10/why-do-we-need-a-unified-standard-at-all-1.html HomeGrid Forum Blog - Why do we need a unified standard at all?]</ref>
 
On December 2008, [[ITU-T]] adopted Recommendation [[G.hn]] (also known as [[G.9960]]), which is a next generation home networking standard that specifies a common PHY/MAC that can operate over any home wiring (power lines, phone lines or coaxial cables).<ref>[http://www.itu.int/ITU-T/newslog/New+Global+Standard+For+Fully+Networked+Home.aspx New global standard for fully networked home], ITU-T Press Release</ref>
 
===IMS architecture for IPTV===
There is a growing standardization effort on the use of the 3GPP [[IP Multimedia Subsystem]] (IMS) as an architecture for supporting IPTV services in carriers networks. Both ITU-T and ETSI are working on so-called "IMS-based IPTV" standards (see e.g. ETSI TS 182 027<ref>[http://pda.etsi.org/pda/home.asp?wki_id=CaDXV0CcRxTVYVVcl3FyX ETSI TS 182 027]</ref>). The benefits of this approach are obvious. Carriers will be able to offer both voice and IPTV services over the same core infrastructure and the implementation of services combining conventional TV services with telephony features (e.g. caller ID on the TV screen) will become straigthforward.<ref>[http://www.staff.city.ac.uk/~veselin/publications/Sivchenko_ACM07.pdf IMS-based IPTV services - architecture and implementation]</ref>
The MultiService Forum recenly conducted interoperability of IMS-based IPTV solutions during its GMI event in 2008 (http://www.msforum.org/interoperability/02-MGS81044-MFS_Whitepaper.pdf).
 
==Protocols==
IPTV covers both [[live TV]] ([[multicasting]]) as well as stored video (Video on Demand VOD). The playback of IPTV requires either a [[personal computer]] or a [[set-top box]] connected to a TV. Video content is typically compressed using either a [[MPEG-2]] or a [[MPEG-4]] codec and then sent in an [[MPEG transport stream]] delivered via [[IP Multicast]] in case of live TV or via IP Unicast in case of Video on Demand. IP Multicast is a method in which information can be sent to multiple computers at the same time. The newly released (MPEG-4) [[H.264/MPEG-4 AVC|H.264]] codec is increasingly used to replace the older MPEG-2 codec.
 
In standards-based IPTV systems, the primary underlying protocols used are:
 
* Live TV uses [[IGMP#IGMP version 2.|IGMP version 2]] or [[IGMP#IGMP version 3.|IGMP version 3]] for IPv4 for connecting to a multicast stream (TV channel) and for changing from one multicast stream to another (TV channel change).
 
* VOD is using the [[Real Time Streaming Protocol]] (RTSP).
 
* [[N-PVR]] (Network-based Personal Video Recorder) is also using the [[Real Time Streaming Protocol]] (RTSP).
 
Network Personal Video Recording is a consumer service where real-time broadcast television is captured in the network on a server allowing the end user to access the recorded programs on the schedule of their choice, rather than being tied to the broadcast schedule.
The NPVR system provides time-shifted viewing of broadcast programs, allowing subscribers to record and watch programs at their convenience, without the requirement of a truly personal [[PVR]] device. It could be compared as a "PVR that is built into the network" &ndash; however that would be slightly misleading unless the word "Personal" is, of course, changed to "Public" for this context.
 
Subscribers can choose from the programmes available in the network-based library, when they want, without needing yet another device or remote control. However, many people would still prefer to have their own PVR device, as it would allow them to choose exactly what they want to record. This bypasses the strict copyright and licensing regulations, as well as other limitations, that often prevent the network itself from providing "on demand" access to certain programmes (see ''[[Heroes (TV series)|Heroes]]'', below).
 
In [[Greece]], [[On Telecoms]] offers an NPVR service to all subscribers in their basic package with all the programming of all major national Greek TV channels for the last 72 hours. The user has to sign in their contract that they agree that the company will record national programming of the last 72 hours FOR them so that they can come around any legal implications (like the ones mentioned [[NPVR|here]]) as this service would work like a personal PVR.
 
Currently, the only alternatives to IPTV are traditional TV distribution technologies such as [[Terrestrial television|terrestrial]], [[satellite]] and [[cable]]. However, cable can be upgraded to two-way capability and can thus also carry IPTV.
 
==IPTV via satellite==
Although IPTV and conventional [[satellite TV]] distribution have been seen as complementary technologies, they are likely to be increasingly used together in hybrid IPTV networks that deliver the highest levels of performance and reliability. IPTV is largely neutral to the transmission medium, and IP traffic is already routinely carried by satellite for [[Internet backbone]] trunking and corporate [[VSAT]] networks.<ref>Berlocher, Greg and Freyer, Dan. "IP And Satellite: Communications Worlds Merging" ''Via Satellite'' January 2009 p24-28</ref> The use of satellite to carry IP is fundamental to overcoming the greatest shortcoming of IPTV over terrestrial cables – the speed/bandwidth of the connection.
 
The copper twisted pair cabling that forms the [[last mile]] of the telephone/broadband network in many countries is not able to provide a sizeable proportion of the population with an IPTV service that matches even existing terrestrial or satellite digital TV distribution. For a competitive multi-channel TV service, a connection speed of 20Mbit/s is likely to be required, but unavailable to most potential customers.<ref>Taga, Karim. "Hybrid delivery of content for IPTV" ''InterComms'' Issue 11 August 2008 p13-14</ref> The increasing popularity of [[high definition TV]] (with twice the data of [[SD video]]) increases connection speed requirements, or limits IPTV service quality and connection eligibility, yet further.
 
However, satellites are capable of delivering in excess of 100Gbit/s via multi-spot beam technologies, making satellite a clear emerging technology for implementing IPTV networks. Satellite distribution can be included in an IPTV network architecture in several ways. Simplest to implement is an IPTV-[[Direct To Home|DTH]] architecture, in which hybrid DVB/broadband [[set-top boxes]] in subscriber homes integrate satellite and IP reception to give near-infinite bandwidth with return channel capabilities. In such a system, many live TV channels may be multicast via satellite (IP-encapsulated or as conventional [[Digital Video Broadcasting|DVB]] digital TV) with stored video-on-demand transmission via the broadband connection. [[Arqiva]]’s Satellite Media Solutions Division suggests “IPTV works best in a hybrid format. For example, you would use broadband to receive some content and satellite to receive other, such as live channels”.<ref>Holmes, Mark. "Broadcast 2.0: The Changing Scene In Europe" ''Via Satellite'' September 2008 p20-25</ref>
 
The [[Hybrid Broadcast Broadband TV]] (HbbTV) consortium of industry companies is currently promoting and establishing an open European standard for hybrid set-top boxes for the reception of broadcast and broadband digital TV and multimedia applications with a single user interface.<ref>{{cite press release |publisher=HbbTV Consortium |date=August 27, 2009 |url=http://www.hbbtv.org/news/HBBTV_PR_Final.pdf |title=NEW EUROPEAN INITIATIVE MERGES TELEVISION WITH THE POWER OF THE INTERNET}}</ref>
 
An alternative approach is the IPTV version of the [[Headend in the Sky]] cable TV solution. Here, mutilple TV channels are distributed via satellite to the ISP or IPTV provider’s [[point of presence]] (POP) for IP-encapsulated distribution to individual subscribers as required by each subscriber.
 
This can provide a huge selection of channels to subscribers without overburdening Internet trunking to the POP, and enables an IPTV service to be offered to small or remote operators outside the reach of terrestrial high speed broadband connection. An example is a network combining fibre and satellite distribution via an [[SES New Skies]] satellite of 95 channels to Latin America and the Caribbean, operated by IPTV Americas.<ref>{{cite press release |publisher=IPTV Americas|date=January 13, 2009|url= http://www.iptv-americas.tv/releaseDB.php?leng=&notID=47
|title= IPTV Americas Launches First IPTV Satellite Distribution Platform for Latin America and The Caribbean via SES NEW SKIES’ NSS-806}}</ref>
 
While the future development of IPTV probably lies with a number of coexisting architectures and implementations, it’s clear that broadcasting of high bandwidth applications such as IPTV is accomplished more efficiently and cost-effectively using satellite<ref>International Datacasting Corporation [http://www.datacast.com/pg_SolutionIndex.php "Why IP Over Satellite?"]. Accessed January 18, 2009. Company factsheet</ref> and it’s predicted that the majority of global IPTV growth will be fuelled by hybrid networks.<ref>[http://www.satellitetoday.com/via/ednote/140.html "Future Looks Bright For IPTV"] ''Satellite Today'.' Retrieved January 18, 2009.</ref>
 
==Advantages==
The IP-based platform offers significant advantages, including the ability to integrate television with other IP-based services like high speed Internet access and VoIP.
 
A switched IP network also allows for the delivery of significantly more content and functionality. In a typical TV or satellite network, using broadcast video technology, all the content constantly flows downstream to each customer, and the customer switches the content at the set-top box. The customer can select from as many choices as the telecomms, cable or satellite company can stuff into the “pipe” flowing into the home. A switched IP network works differently. Content remains in the network, and only the content the customer selects is sent into the customer’s home. That frees up bandwidth, and the customer’s choice is less restricted by the size of the “pipe” into the home. This also implies that the customer's privacy could be compromised to a greater extent than is possible with traditional TV or satellite networks. It may also provide a means to hack into, or at least disrupt (see [[Denial of Service]]) the private network.
 
===The economics of IPTV===
The cable industry's expenditures of approximately $1 Billion per year are based on network updates to accommodate higher data speeds. Most operators use 2-3 channels to support maximum data speeds of 50 Mb/s to 100 Mb/s. However, because video streams require a high bit rate for much longer periods of time, the expenditures to support high amounts of video traffic will be much greater. This phenomenon is called persistency. Data persistency is routinely 5% while video persistency can easily reach 50%. As video traffic continues to grow, this means that significantly more CMTS downstream channels will be required to carry this video content. Based on today's market, it is likely that industry expenditures for CMTS expansion could exceed $2 Billion a year, virtually all of this expenditure being driven by video traffic. Adoption of IPTV for carrying the majority of this traffic could save the industry approximately 75% of this CapEx expense.<ref>[http://www.bigbandnet.com/index.php/sol_iptv_economics.html?=mrb The Economics of IPTV]</ref>
 
===Interactivity===
An IP-based platform also allows significant opportunities to make the TV viewing experience more interactive and personalized.
The supplier may, for example, include an interactive program guide that allows viewers to search for content by title or actor’s name, or a [[picture-in-picture]] functionality that allows them to “channel surf” without leaving the program they’re watching. Viewers may be able to look up a player’s stats while watching a sports game, or control the camera angle. They also may be able to access photos or music from their PC on their television, use a wireless phone to schedule a recording of their favorite show, or even adjust parental controls so their child can watch a documentary for a school report, while they’re away from home.
 
Note that this is all possible, to some degree, with existing digital terrestrial, satellite and cable networks in tandem with modern [[set top box]]es.{{Citation needed|date=January 2009}} In order that there can take place an interaction between the receiver and the transmitter a feedback channel is needed. Due to this terrestrial, satellite and cable networks for television does not allow interactivity. However, interactivity with those networks can be possible in the combination with different networks like internet or a mobile communication network.
 
===Video on demand===
''Video on demand'' (VoD) permits a customer to browse an online program or film catalog, to watch trailers and to then select a selected recording for playback. The [[playout]] of the selected movie starts nearly instantaneously on the customer's TV or PC.
 
Technically, when the customer selects the movie, a [[point-to-point]]{{dn}} unicast connection is set up between the customer's decoder (SetTopBox or PC) and the delivering streaming server. The signalling for the trick play functionality (pause, slow-motion, wind/rewind etc.) is assured by RTSP (Real Time Streaming Protocol).
 
The most common codecs used for VoD are [[MPEG-2]], [[MPEG-4]] and [[VC-1]].
 
In an attempt to avoid content piracy, the VoD content is usually encrypted. Whilst [[encryption]] of satellite and cable TV broadcasts is an old practice, with IPTV technology it can effectively be thought of as a form of [[Digital Rights Management]]. A film that is chosen, for example, may be playable for 24 hours following payment, after which time it becomes unavailable.
 
===IPTV-based converged services===
Another advantage of an IP-based network is the opportunity for integration and convergence. This opportunity is amplified when using IMS-based solutions.<ref>[http://c-mobile.ptinovacao.pt/files/PaperMobilWare2008.pdf Session and Media SIgnalling for IPTV via IMS]</ref> Converged services implies interaction of existing services in a seamless manner to create new value added services. One good example is On-Screen Caller ID, getting Caller ID on your TV and the ability to handle it (send it to voice mail, etc). IP-based services will help to enable efforts to provide consumers anytime-anywhere access to content over their televisions, PCs and cell phones (for example see http://www.ericsson.com/campaign/televisionary/), and to integrate services and content to tie them together. Within businesses and institutions, IPTV eliminates the need to run a parallel infrastructure to deliver live and stored video services.
 
==Limitations==
IPTV is sensitive to packet loss and delays if the streamed data is unreliable. IPTV has strict minimum speed requirements in order to facilitate the right number of frames per second to deliver moving pictures. This means that the limited connection speed/bandwidth available for a large IPTV customer base can reduce the service quality delivered.
 
Although a few countries have very high speed broadband-enabled populations, such as [[South Korea]] with 6 million homes benefiting from a minimum connection speed of 100Mbit/s, in other countries (such as the UK) legacy networks struggle to provide 3-5 Mbit/s<ref>Bulkley, Kate. "IPTV’s Eastern Promise" ''Digital TV Europe'' October 2008 p48</ref> and so simultaneous provision to the home of TV channels, VOIP and Internet access may not be viable. The last mile delivery for IPTV usually has a bandwidth restriction that only allows a small number of TV channels – typically from one to three – to be delivered.<ref>Brown, Peter J. "Super Headends And High Expectations" ''Via Satellite'' April 2006 p18-30</ref>
 
The same problem has also proved troublesome when attempting to stream IPTV across wireless links within the home. Improvements in wireless technology are now starting to provide equipment to solve the problem.<ref>Market Wire [http://findarticles.com/p/articles/mi_pwwi/is_200806/ai_n26682515 "ZyXEL Announces Industry's First ADSL2/2+ 802.11n Gateway and New IPTV Product Offerings"] June 2008 </ref>
 
Due to the limitations of wireless, most IPTV service providers today use wired home networking technologies instead of wireless technologies like [[802.11]]. Service Providers such as [[AT&T]] (which makes extensive use of wireline home networking as part of its [[U-Verse]] IPTV service) have expressed support for the work done in this direction by [[ITU-T]], which has adopted Recommendation [[G.hn]] (also known as [[G.9960]]), which is a next generation home networking standard that specifies a common PHY/MAC that can operate over any home wiring (power lines, phone lines or coaxial cables).<ref>[http://www.marketwatch.com/news/story/homepna-homegrid-sign-liaison-agreement/story.aspx?guid={C8E4BB07-375A-41E5-8B05-2E33222E44C2}&dist=msr_9 HomePNA and HomeGrid Sign Liaison Agreement], Groups Work to Promote New ITU G.hn Global Wired Home Networking Standard</ref><ref>[http://www.everywire.com/2009/02/att-participating-in-ghn-standard-development-1.html AT&T Participating in G.hn Standard Development]</ref>
 
===Latency===
The [[latency (engineering)|latency]] inherent in the use of [[satellite internet]] is often held up as reason why satellites cannot be successfully used for IPTV, but in practice latency is not an important factor for IPTV. An IPTV service does not require real-time transmission, as is the case with telephony or videoconferencing services.
 
It is the latency of response to requests to change channel, display an EPG, etc that most affects customers’ perceived quality of service, and these problems affect satellite IPTV no more than terrestrial IPTV. Indeed, command latency problems, faced by terrestrial IPTV networks with insufficient bandwidth as their customer base grows, may be solved by the high capacity of satellite distribution.
 
Satellite distribution does suffer from latency – the time for the signal to travel up from the hub to the satellite and back down to the user is around 0.25 seconds, and cannot be reduced. However, the effects of this delay are mitigated in real-life systems using data compression, TCP-acceleration, and HTTP pre-fetching.<ref>Newtec Productions NV [http://www.newtec.be/fileadmin/webfolder/brochures/Sat3Play_Brochure_2008/R2_01_2008_Sat3Play_Leaflet_Terminal_web.pdf "TP200 Sat3Play Broadband Terminal"] (Version R2/01.2008). Satellite Internet Modem factsheet</ref>
 
Satellite latency can be detrimental to especially time-sensitive applications such as on-line gaming (although it only seriously affects the likes of first-person shooters while many [[MMOG]]s can operate well over satellite internet<ref>Tom’s Hardware [http://www.tomshardware.co.uk/forum/page-99005_25_0.html "How much latency is too much for Online Gaming?"]. Accessed January 23, 2009. Internet Forum</ref>), but IPTV is typically a [[Simplex communication|simplex]] operation (one-way transmission) and latency is not a critical factor for video transmission.
 
Existing video transmission systems of both analogue and digital formats already introduce known quantifiable delays. Indeed, existing [[Digital Video Broadcasting|DVB]] TV channels that [[simulcast]] by both terrestrial and satellite transmissions, experience the same 0.25s delay difference between the two services with no detrimental effect, and it goes unnoticed by viewers.
 
==Privacy implications==
Due to limitations in bandwidth, an IPTV channel is delivered to the user one at a time, as opposed to the traditional multiplexed delivery. Changing a channel requires requesting the head-end server to provide a different broadcast stream, much like [[Video on demand|VOD]] (For VOD the stream is delivered using [[Unicast]], for the normal TV signal [[Multicast]] is used). This could enable the service provider to accurately track each and every programme watched and the duration of watching for each viewer, broadcasters and advertisers could then understand their audience and programming better with accurate data and targeted advertising. <ref>[http://www.cedmagazine.com/iptv-privacy-risks.aspx IPTV privacy risks<!-- Bot generated title -->]</ref>
 
==Vendors==
A small number of companies supply most current IPTV systems. Some, such as [[Imagenio]], were formed by telecoms operators themselves, to minimise external costs, a tactic also used by [[PCCW]] of [[Hong Kong]]. Some major telecoms vendors are also active in this space, notably [[Alcatel-Lucent]] (sometimes working with Imagenio), [[Ericsson]] (notably since acquiring [[Tandberg Television]]), [[NEC]], [[Thomson SA|Thomson]], and [[ZTE]], as are some IT houses, led by [[Microsoft]]. California-based [[UTStarcom|UTStarcom, Inc.]], Tennessee-based Worley Consulting, Tokyo-based The New Media Group and Oslo/Norway-based SnapTV also offer end-to-end networking infrastructure for IPTV-based services, and Hong Kong-based BNS Ltd. provides turnkey open platform IPTV technology solutions. Global sales of IPTV systems exceeded 2 billion USD in 2007.
 
Many of these IPTV solution vendors participated in the [[biennial]] [http://www.fiercetelecom.com/story/msf-announces-details-gmi-2008/2008-09-10?utm_medium=rss&utm_source=telecom_M&cmp-id=OTC-RSS-FT0 Global [[MSF]] Interoperability 2008] (GMI) event which was coordinated by the [[MultiService Forum]] (MSF) at five sites worldwide from 20- to 31-October 2008. Test equipment vendors including [[Codenomicon]], Empirix, Ixia, [[Mu Dynamics]] and [[Spirent]] joined solution vendors such as the companies listed above in one of the largest IPTV proving grounds ever deployed.
 
==Service bundling==
For residential users, IPTV is often provided in conjunction with [[Video on Demand]] and may be bundled with [[Internet service]]s such as [[Internet access]] and [[Voice over Internet Protocol]] (VoIP) telecommunications services. Commercial bundling of IPTV, VoIP and Internet access is sometimes referred to in marketing as [[triple play (telecommunications)|''triple play'']] service. When these three are offered with mobility, the service may be referred to as ''quadruple play''.
 
==IPTV Regulation==
Historically, broadcast television has been regulated differently than telecommunications. As IPTV allows TV and VoD to be transmitted over IP networks new regulatory issues arise.<ref>{{PDFlink|[http://www.ericsson.com/ericsson/corpinfo/publications/ericsson_business_review/pdf/308/308_38_41_reshaping.pdf Ericson report on need for regulation]|217&nbsp;KB}}</ref>
Professor Eli M. Noam highlights in his report "TV or Not TV: Three Screens, One Regulation?" some of the key challenges with sector specific regulation that is becoming obsolete due to convergence in this field.<ref>[http://www.crtc.gc.ca/eng/media/noam2008.htm TV or Not TV<!-- Bot generated title -->]</ref>
 
==See also==
* [[Comparison of streaming media systems]]
* [[Comparison of video services]]
* [[Content delivery network]]
* [[Grid casting]]
* [[Internet television]]
* [[List of music streaming services]]
* [[List of streaming media systems]]
* [[Multicast]]
* [[P2PTV]]
* [[Protection of Broadcasts and Broadcasting Organizations Treaty]]
* [[Software as a service]]
* [[Streaming media]]
* [[Webcast]]
* [[Web television]]
 
==References==
{{reflist|colwidth=30em}}
*Securing Converged IP Networks, Tyson Macaulay, Auerbach 2006 (ISBN 0849375800)
*[http://papers.ssrn.com/sol3/papers.cfm?abstract_id=932980 "Does Video Delivered Over A Telephone Network Require A Cable Franchise?"] AEI-Brookings Joint Center for Regulatory Studies
-->
== Eksteraj ligiloj ==
*[http://www.oipf.tv/ Open IPTV Forum]
*[http://www.itu.int/ITU-T/IPTV/ ITU IPTV Focus Group]
*[http://arstechnica.com/guides/other/iptv.ars An Introduction to IPTV]
*[http://isoc.nl/activ/2008-SIPSIG-standards-OskarVanDeventer-IMS-basedIPTV.ppt IPTV over IMS]
*[http://www.alcatel.com/bnd/news/ip/heavy_reading/HR_wp_Assuring_QOE_4_IPTV.pdf Assuring Quality of Experience for IPTV] key challenges and solution approaches for service control and assurance
*[http://www.hbbtv.org HbbTV website]
 
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