Internet Protocol television (IPTV) is the delivery of television content using signals based on the logical Internet protocol (IP), rather than through traditional terrestrial, satellite signal, 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 data (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 media streamed from the Internet, which is known as Internet TV. IPTV is also 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, as well as IPTV deployment for media delivery around corporate and private IT 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 three main groups:
- Live television and live media, with or without related interactivity;
- Time-shifted 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);
- Video on demand (VOD): browse and view items in a stored media catalogue.
One official definition approved by the International Telecommunication Union focus group on IPTV (ITU-T FG IPTV) is:
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.Another definition of IPTV, relating to the telecommunications industry, is the one given by Alliance for Telecommunications Industry Solutions (ATIS) IPTV Exploratory Group on 2005:
IPTV is defined as the secure and reliable delivery to subscribers of entertainment video and related services. These services may include, for example, Live TV, Video On Demand (VOD) and Interactive TV (iTV). These services are delivered across an access agnostic, packet switched network that employs the IP protocol to transport the audio, video and control signals. In contrast to video over the public Internet, with IPTV deployments, network security and performance are tightly managed to ensure a superior entertainment experience, resulting in a compelling business environment for content providers, advertisers and customers alike.
The term IPTV first appeared in 1995 with the founding of Precept Software by Judith Estrin and Bill Carrico. Precept developed an Internet video product named IP/TV. IP/TV was a multicast backbone (MBONE) compatible Windows and Unix-based application that transmitted single and multi-source audio and 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. Cisco retains the IP/TV trademark.
Internet radio company AudioNet started the first continuous live webcasts with content from WFAA-TV in January 1998 and KCTU-LP on January 10, 1998.
Kingston Communications, a regional telecommunications operator in the UK, launched KIT (Kingston Interactive Television) the brainchild of Matt Child, an IPTV over digital subscriber line (DSL) broadband interactive TV service in September 1999 after conducting various TV and video on demand (VoD) trials. 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 Internet Protocol (IP) video 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 supplier any longer; TeliaSonera, who launched their service later now has more customers.
In 2007, TPG became the first internet service provider in Australia to launch IPTV. Complementary to its ADSL2+ package this was, and still is, free of charge to customers on eligible plans and now offers over 45 local free to air channels and international channels. By 2010, iiNet and Telstra launched IPTV services in conjunction to internet plans but with extra fees.
In 2008, PTCL (Pakistan Telecommunication Company Limited) 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 and more than 500 titles for VOD with key features such as:
- EPG (electronic programme guide)
- Parental Control
- Time-Shift Television
- VOD (video on demand)
In 2016, KCTV (Korean Central Television) introduced the Set-top box called "Manbang" (meaning ‘everywhere’ or ‘every direction’), claiming to provide video-on-demand services in North Korea via quasi-internet protocol television (IPTV). With "Manbang", viewers are able to watch five different TV channels in real-time, find information related to the leader’s activities and Juche ideology, and read articles from the newspaper Rodong Sinmun and the Korean Central News Agency (KCNA). According to KCTV, viewers can use the service not only in Pyongyang, but also in Sinuiju and Sariwon. Stating that the demands for the equipment are "particularly" high in Sinuiju, with several hundred users in the region.
IPTV covers both live TV (multicast) as well as stored video-on-demand/VoD (unicast). Playback requires a broadband device connected to either a fixed or wireless IP network in the form of either a standalone personal computer or limited embedded OS device such as a smartphone, touch screen tablet, game console, connected TV or set-top box. Video compression is provided by either a H.263 or H.264 derived codec, audio is compressed via a MDCT based codec and then encapsulated in either an MPEG transport stream or RTP packets or Flash Video packets for live or VoD streaming. IP multicasting allows for live data to be sent to multiple receivers using a single multicast group address. H.264/MPEG-4 AVC is commonly used for internet streaming over higher bit rate standards such as H.261 and H.263 which were more designed for ISDN video conferencing. H.262/MPEG-1/2 is generally not used as the bandwidth required would quite easily saturate a network which is why they are only used in single link broadcast or storage applications.
In standards-based IPTV systems, the primary underlying protocols used are:
- Service provider-based streaming:
- IGMP for subscribing to a live multicast stream (TV channel) and for changing from one live multicast stream to another (TV channel change). IP multicast operates within LANs (including VLANs) and across WANs also. IP multicast is usually routed in the network core by Protocol Independent Multicast (PIM), setting up correct distribution of multicast streams (TV channels) from their source all the way to the customers who wants to view them, duplicating received packets as needed. On-demand content uses a negotiated unicast connection. Real-time Transport Protocol (RTP) over User Datagram Protocol (UDP) or the lower overhead H.222 transport stream over Transmission Control Protocol (TCP) are generally the preferred methods of encapsulation.
- Web-based unicast only live and VoD streaming:
- Adobe Flash Player prefers RTMP over TCP with setup and control via either AMF or XML or JSON transactions.
- Apple iOS uses HLS adaptive bitrate streaming over HTTP with setup and control via an embedded M3U playlist file.
- Microsoft Silverlight uses smooth streaming (adaptive bitrate streaming) over HTTP.
- Web-based multicast live and unicast VoD streaming:
- The Internet Engineering Task Force (IETF) recommends RTP over UDP or TCP transports with setup and control using RTSP over TCP.
- Connected TVs, game consoles, set-top boxes and network personal video recorders:
- local network content uses UPnP AV for unicast via HTTP over TCP or for multicast live RTP over UDP.
- Web-based content is provided through either inline Web plug-ins or a television broadcast-based application that uses a middleware language such as MHEG-5 that triggers an event such as loading an inline Web browser using an Adobe Flash Player plug-in.
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.
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