Телевидение по интернет-протоколу (IPTV)

Television transmitted over a computer network

Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, IPTV offers the ability to stream the source media continuously. As a result, a client media player can begin playing the content (such as a TV channel) almost immediately. This is known as streaming media. Although IPTV uses the Internet protocol it is not limited to television streamed from the Internet (Internet television). IPTV is widely deployed in subscriber based telecommunications networks with high speed access channels into end user premises via set top boxes or other customer premises equipment. IPTV is also used for media delivery around corporate and private networks. IPTV in the telecommunications arena is notable for its ongoing standardisation process (e. g., European Telecommunications Standards Institute). IPTV services may be classified into live television and live media, with or without related interactivity; time shifting of media, e. g., catch up TV (replays a TV show that was broadcast hours or days ago), start over TV (replays the current TV show from its beginning); and video on demand (VOD) which involves browsing and viewing items of a media catalogue.

Up until the early 1990s, it was not thought possible that a television programme could be squeezed into the limited telecommunication bandwidth of a copper telephone cable to provide a video on demand (VOD) television service of acceptable quality, as the required bandwidth of a digital television signal was around 200Mbit/s, which was 2,000 times greater than the bandwidth of a speech signal over a copper telephone wire. VOD services were only made possible as a result of two major technological developments: motion compensated DCT video compression and asymmetric digital subscriber line (ADSL) data transmission. Motion compensated DCT algorithms for video coding standards include the H.26x formats from 1988 onwards and the MPEG formats from 1991 onwards. Motion compensated DCT video compression significantly reduced the amount of bandwidth required for a television signal, while at the same time ADSL increased the bandwidth of data that could be sent over a copper telephone wire. ADSL increased the bandwidth of a telephone line from around 100kbit/s to 2Mbit/s, while DCT compression reduced the required bandwidth of a digital television signal from around 200Mbit/s down to about 2Mbit/s. The combination of DCT and ADSL technologies made it possible to practically implement VOD services at around 2Mbit/s bandwidth in the 1990s. Cisco retains the IP/TV trademark. Telecommunications company US West (later Qwest) launched an IPTV service called TeleChoice in Phoenix, Arizona in 1998 using VDSL technology, becoming the first company in the United States to provide digital television over telephone lines. The service was shut down in 2008. Internet radio company AudioNet started the first continuous live webcasts with content from WFAA TV in January 1998 and KCTU LP on 10 January 1998. Kingston Communications, a regional telecommunications operator in the UK, launched Kingston Interactive Television (KIT), an IPTV over digital subscriber line (DSL) service in September 1999. The operator added additional VOD service in October 2001 with Yes TV, a VOD content provider. Kingston was one of the first companies in the world to introduce IPTV and IP VOD over ADSL as a commercial service. The service became the reference for various changes to UK Government regulations and policy on IPTV. In 2006, the KIT service was discontinued, subscribers having declined from a peak of 10,000 to 4,000. In 1999, NBTel (now known as Bell Aliant) was the first to commercially deploy Internet protocol television over DSL in Canada using the Alcatel 7350 DSLAM and middleware created by iMagic TV (owned by NBTel's parent company Bruncor). The service was marketed under the brand VibeVision in New Brunswick, and later expanded into Nova Scotia in early 2000 after the formation of Aliant. iMagic TV was later sold to Alcatel. In 2002, Sasktel was the second in Canada to commercially deploy IPTV over DSL, using the Lucent Stinger DSL platform. In 2005, SureWest Communications was the first North American company to offer high definition television (HDTV) channels over an IPTV service. In 2005, Bredbandsbolaget launched its IPTV service as the first service provider in Sweden. As of January 2009, they are not the biggest provider any longer; TeliaSonera, who launched their service later, now has more customers. In 2007, TPG launched their IPTV service in Australia after a limited beta. By 2010, iiNet and Telstra launched IPTV services in conjunction to internet plans. In 2008, Pakistan Telecommunication Company Limited (PTCL) launched IPTV under the brand name of PTCL Smart TV in Pakistan. This service is available in 150 major cities of the country offering 140 live channels. In 2010, CenturyLink – after acquiring Embarq (2009) and Qwest (2010) – entered five U. S. markets with an IPTV service called Prism. This was after successful test marketing in Florida. Later in 2010, Bell Canada (a major division, if not the largest division of BCE) announced it would begin offering residential and business/commercial customers in Montreal, Quebec and Toronto, Ontario IPTV over a number of different modalities, including fibre to the home, fibre to the node and DSL. This flavour of IPTV would be packaged with other services and branded as "Bell Fibe," providing Canadian customers with everything from local analogue trunk connectivity (POTS), to DSL and fibre Internet to TV service via IPTV. Bell further announced in the September 13th (2010) press release it would begin deploying fiber optic Ethernet to homes in Montreal and Toronto. Bell has since continued to install fiber optic Ethernet to homes (fibre to the home) across Ontario and Quebec, Bell Canada's two largest customer territories. Bell was very successful with the deployment of the Bell Fibe product offering. Many customers in Ontario and Quebec switched from legacy (coaxial) cable companies to Bell's Fibe product because of Bell's marketing around IPTV and their at home wireless PVR offering. Bell's wireless PVR would permit customers to place a TV anywhere they wanted as long as they had a power outlet. Bell Fibe TV commercials would show young families watching TV outside on the couch with large 70+ inch LCDs and their Bell Fibe wireless PVR. In Brazil, since at least 2012, Vivo has been offering the service Vivo TV Fibra in 200+ cities where it has FTTH coverage (4Q 2020 data) Since at least 2018, Oi has also been offering IPTV under its FTTH service "Oi Fibra". Also, several regional FTTH providers also offer IPTV along with FTTH internet services. In 2016, Korean Central Television (KCTV) introduced the set top box called Manbang, reportedly providing video on demand services in North Korea via quasi internet protocol television (IPTV). Manbang allows viewers to watch five different TV channels in real time, and find political information regarding the Supreme Leader and Juche ideology, and read articles from state run news organizations.

The global IPTV market was expected to grow from 28 million subscribers at US$12 billion revenue in 2009 to 83 million and US$38 billion in 2013. Europe and Asia are the leading territories in terms of the overall number of subscribers. But in terms of service revenues, Europe and North America generate a larger share of global revenue, due to very low average revenue per user (ARPU) in China and India, the fastest growing (and ultimately, the biggest markets) is Asia. Services also launched in Bosnia and Herzegovina, Bulgaria, Pakistan, Canada, Croatia, Lithuania, Moldova, Montenegro, Morocco, North Macedonia, Poland, Mongolia, Romania, Serbia, Slovenia, the Netherlands, Georgia, Greece, Denmark, Finland, Estonia, Czech Republic, Slovakia, Hungary, Norway, Sweden, Iceland, Latvia, Turkey, Colombia, Chile and Uzbekistan. The United Kingdom launched IPTV early and after a slow initial growth, in February 2009 BT announced that it had reached 398,000 subscribers to its BT Vision service. 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, Nepal Pakistan and India. but significant plans exist in countries such as Russia. Kazakhstan introduced its own IPTV services by the national provider Kazakhtelecom JSC and content integrator Alacast under the "iD TV" brand in two major cities Astana and Almaty in 2009 and is about to go nationwide starting 2010. Australian ISP iiNet launched Australia's first IPTV with Fetch TV. In India, IPTV was launched by MTNL, BSNL and Jio in New Delhi, Mumbai and Punjab. APSFL is another IPTV provider in the state of Andhra Pradesh. In Nepal, IPTV was first launched by NEW IT VENTURE CORPORATION called Net TV Nepal, the service can be accessed through its app, web app and Set top boxes provided by local ISPs, another IPTV was started by Nepal Telecom called WOW Time in 2016 which can be accessed through its app. In Sri Lanka, IPTV was launched by Sri Lanka Telecom (operated by SLT VisionCom) in 2008, under the brand name of PEO TV. This service is available throughout the country. Dialog TV has been available through the service since 2018. In Pakistan, IPTV was launched by PTCL in 2008, under the brand name of PTCL Smart TV. This service is available in 150 major cities of the country. In the Philippines, PLDT offers Cignal IPTV services as an add on in certain ADSL and fiber optic plans. In Malaysia, various companies have attempted to launch IPTV services since 2005. Failed PayTV provider MiTV attempted to use an IPTV over UHF service but the service failed to take off. HyppTV was supposed to use an IPTV based system, but not true IPTV as it does not provide a set top box and requires users to view channels using a computer. True IPTV providers available in the country at the moment are Fine TV and DETV. In Q2 2010, Telekom Malaysia launched IPTV services through their fibre to the home product Unifi in select areas. In April 2010, Astro began testing IPTV services on TIME dotCom Berhad's high speed fibre to the home optical fibre network. In December 2010, Astro began trials with customers in high rise condominium buildings around the Mont Kiara area. In April 2011, Astro commercially launched its IPTV services under the tag line "The One and Only Line You'll Ever Need", a triple play offering in conjunction with TIME dotCom Berhad that provides all the Astro programming via IPTV, together with voice telephone services and broadband Internet access all through the same fibre optic connection into the customer's home. In 2020, Astro launched "Plug and Play", which uses Unicast technology for streaming TV. In Turkey, TTNET launched IPTV services under the name IPtivibu in 2010. It was available in pilot areas in the cities of Istanbul, İzmir and Ankara. As of 2011, IPTV service is launched as a large scale commercial service and widely available across the country under the trademark "Tivibu EV". Superonline plans to provide IPTV under the different name "WebTV" in 2011. Türk Telekom started building the fibre optic substructure for IPTV in late 2007.

IPTV has been widely used since around 2002 to distribute television and audio visual (AV) media around businesses and commercial sites, whether as live TV channels or Video on Demand (VOD). Examples of types of commercial users include airports, schools, offices, hotels, and sports stadiums, to name just a few. Hotel television systems are the in suite television content presented in hotel rooms, other hotel environments and in the hospitality industry for in room entertainment, as well as hospitals, assisted living, senior care and nursing homes. These services may be free for the guest or paid, depending on the service and the individual hotel's or hotel chain's policy. Generally, these services are controlled by using the remote control.

An IPTV head end is a place where live TV channels and AV sources are encoded, encrypted, and delivered as IP multicast streams. Meanwhile, a Video on Demand (VOD) platform stores on demand video assets and serves them as IP unicast streams when a user requests them. Sometimes, the VOD platform is located within the IPTV head end. An interactive portal allows users to navigate within the different IPTV services, such as the VOD catalogue. A delivery network is a packet switched network that carries IP packets, including unicast and multicast streams. Endpoints refer to user equipment that can request, decode, and deliver IPTV streams for display to the user. This can include computers, mobile devices, and set top boxes. At a residential IPTV user's home, the home TV gateway is the piece of equipment that terminates the access link from the delivery network. Lastly, the user set top box is the piece of endpoint equipment that decodes and decrypts TV and VOD streams for display on the TV screen.

Depending on the network architecture of the service provider, there are two main types of video server architecture that can be considered for IPTV deployment: centralised and distributed. The centralised architecture model is a relatively simple and easy to manage solution. Because all media content is stored in centralised servers, it does not require a comprehensive content distribution system. Centralised architecture is generally good for a network that provides relatively small VOD service deployment, has adequate core and edge bandwidth or has an efficient content delivery network (CDN). A distributed architecture has bandwidth usage advantages and inherent system management features that are essential for managing a larger server network. Distributed architecture requires intelligent and sophisticated content distribution technologies to augment effective delivery of multimedia content over the service provider's network.

In many cases, the residential gateway that provides connectivity with the Internet access network is not located close 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. Networking technologies that take advantage of existing home wiring (such as power lines, phone lines or coaxial cables) or of wireless hardware have become common solutions for this problem, although fragmentation in the wired home networking market has limited somewhat the growth in this market. In 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). Groups such as the Multimedia over Coax Alliance, HomePlug Powerline Alliance, Home Phoneline Networking Alliance, and Quasar Alliance (Plastic Optical Fibre) each advocate their own technologies.

There is a growing standardisation effort on the use of the 3GPP IP Multimedia Subsystem (IMS) as an architecture for supporting IPTV services in telecommunications carrier networks. Both ITU T and ETSI are working on so called "IMS based IPTV" standards (see e. g. ETSI TS 182 027). 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 straightforward.

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. 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. The copper twisted pair cabling that forms the last mile of the telephone and 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 20 Mbit/s is likely to be required, but unavailable to most potential customers. The increasing popularity of high definition television increases connection speed requirements or limits IPTV service quality and connection eligibility even further. However, satellites are capable of delivering in excess of 100 Gbit/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. The 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 additional bandwidth with return channel capabilities. In such a system, many live TV channels may be multicast via satellite and supplemented 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".

Hybrid IPTV refers to the combination of traditional broadcast TV services and video delivered over either managed IP networks or the public Internet. It is an increasing trend in both the consumer and pay TV markets. The growth of Hybrid IPTV is driven by two major factors. Since the emergence of online video aggregation sites, like YouTube and Vimeo in the mid 2000s, traditional pay TV operators have come under increasing pressure to provide their subscribers with a means of viewing Internet based video on their televisions. At the same time, specialist IP based operators have looked for ways to offer analogue and digital terrestrial services to their operations, without adding either additional cost or complexity to their transmission operations. Bandwidth is a valuable asset for operators, so many have looked for alternative ways to deliver these new services without investing in additional network infrastructures. A hybrid set top allows content from a range of sources, including terrestrial broadcast, satellite, and cable, to be brought together with video delivered over the Internet via an Ethernet connection on the device. This enables television viewers to access a greater variety of content on their TV sets, without the need for a separate box for each service. Hybrid IPTV set top boxes may also enable users to access a range of advanced interactive services, such as VOD, catch up TV, as well as Internet applications, including video telephony, surveillance, gaming, shopping, e government accessed via a television set. From a pay TV operator's perspective, a hybrid IPTV set top box gives them greater long term flexibility to deploy new services and applications as and when consumers require, most often without the need to upgrade equipment or for a technician to visit and reconfigure or swap out the device. This reduces the cost of launching new services, increases speed to market and limits disruption for consumers. The Hybrid Broadcast Broadband TV (HbbTV) consortium of industry companies the establishment of 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. These trends led to the development of Hybrid Broadcast Broadband TV set top boxes that included both a broadcast tuner and an Internet connection – usually via an Ethernet port. The first commercially available hybrid IPTV set top box was developed by Advanced Digital Broadcast, a developer of digital television hardware and software, in 2005. The platform was developed for Spanish pay TV operator Telefonica, and used as part of its Movistar TV service, launched to subscribers at the end of 2005. An alternative approach is the IPTV version of the Headend in the Sky cable TV solution. Here, multiple 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 incoming Internet to the POP, and enables an IPTV service to be offered to small or remote operators outside the reach of terrestrial high speed WAN 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.

The Internet protocol 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.

An IP based platform also allows significant opportunities to make the TV viewing experience more interactive and personalised. The provider may, for example, include an interactive programme 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 programme 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 favourite show, or even adjust parental controls so their child can watch a documentary for a school report, while they're away from home. A feedback channel from the viewer to the provider is required for this interactivity. Terrestrial, satellite, and some cable networks for television do not feature a feedback channel and thus don't allow interactivity. However, interactivity with those networks can be possible by combining TV networks with data networks such as the Internet or a mobile communication network.

IPTV technology is used for video on demand (VOD), which permits a customer to browse an online programme or film catalogue, to watch trailers and to then select a program. The playout of the selected item starts nearly instantaneously on the customer's TV or PC. Technically, when the customer selects the program, a point to point unicast connection is set up between the customer's decoder (set top box or PC) and the delivering streaming server. The signalling for the trick mode functionality (pause, slow motion, wind/rewind etc.) may be communicated using, for instance, RTSP. In an attempt to avoid content piracy, the VOD content is usually encrypted and digital rights management may be applied. A film that is chosen, for example, may be playable for 24 hours following payment, after which time it becomes unavailable.

Another advantage is the opportunity for integration and convergence. This opportunity is amplified when using IMS based solutions. Converged services implies interaction of existing services in a seamless manner to create new value added services. One example is on screen caller ID, getting caller ID on a TV, and the ability to handle the call (send it to voice mail, etc.). IP based services help to provide consumers anytime and anywhere access to content over their televisions, PCs, and mobile device, 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.

IPTV is sensitive to packet loss and delays. An IPTV channel has a minimum bandwidth requirement. Some systems are able to adapt to lower available bandwidth by reducing picture quality. Although a few countries have very high speed broadband enabled populations, in other countries legacy networks struggle to provide 3–5 Mbit/s and so simultaneous use of IPTV, 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 simultaneous TV channel streams – typically from one to three – to be delivered.

The network delay inherent in the use of satellite Internet access is often held up as a reason why satellites cannot be successfully used for IPTV. In practice, however, delay is not an important factor for IPTV, since it is a service that does not require real time transmission, as is the case with telephony or videoconferencing services. It is the delay of response to requests to change channel, display an EPG, etc. that most affects customers’ perceived quality of service. Existing video transmission systems of both analogue and digital formats already introduce known quantifiable delays. Existing DVB TV channels that simulcast by both terrestrial and satellite transmissions experience the same 0.25 second delay difference between the two services with no detrimental effect, and it goes unnoticed by viewers.

Digital video is a sequence of digital images, called frames, each made up of pixels or picture elements. Three bytes are typically used to represent the colour of the high quality image. Movies use 24 frames per second, North America television uses approximately 30 frames per second where the Europe television frame rate is 25 frames per second. Each digital video has dimensions width and height; SDTV is pixels, HDTV uses up to pixels. For checking the bandwidth requirements, you need to dimension your IPTV service, such as defining number of SD and HD TV channels, number of planned subscribers, VOD and nPVR concurrency. Based on these, you can calculate required bandwidth on each DSL line, in access network and in core IP network.

Due to limitations in bandwidth, an IPTV channel is delivered to the user one at a time. Changing a channel requires requesting the head end server to provide a different broadcast stream, much like VOD. This could enable the service provider to accurately track each and every programme watched and the duration of watching for each viewer. In conjunction with regulatory differences between IPTV and cable TV, this tracking could pose a threat to privacy according to critics. For IP multicast scenarios, since a particular multicast group (TV channel) needs to be requested before it can be viewed, the same privacy concerns apply.

Some major telecoms vendors are active in this space, notably Accenture (Accenture Video Solution), Alcatel Lucent (sometimes working with Movistar TV), Ericsson (notably since acquiring Tandberg Television), Huawei, NEC, PTCL Smart TV, Sri Lanka Telecom, Thomson, and ZTE, as are some IT houses, led by Microsoft. Miami based AlphaOTT, Tokyo based The New Media Group, Malaysian based Select TV, Oslo/Norway based SnapTV, and California based UTStarcom, Inc. also offer end to end networking infrastructure for IPTV based services, and Hong Kong based BNS Ltd. provides turnkey open platform IPTV technology solutions. Others include Movistar TV and PCCW. Google Fiber offers an IPTV service in various US cities which includes up to 1 Gigabit speed internet and over 290 channels depending on package via the fibre optic network being built out in Kansas City Kansas and Kansas City Missouri. Many of these IPTV solution vendors participated in the biennial Multiservice Switching Forum 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 Netrounds, 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.

For residential users, IPTV is often provided in conjunction with VOD and may be bundled with Internet services 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 service. When these three are offered with cellular service, the combined service may be referred to as quadruple play.

Historically, cable TV operators have been regulated differently from telecommunication operators. As IPTV allows TV and VOD to be transmitted over the Internet, new regulatory issues arise. 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.