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File:EnRoute System on B787-8.JPG

An example of an in-flight entertainment system using VOD/AVOD technology aboard an Air Canada Boeing 787 Dreamliner

Video on demand (VOD) is a video media distribution system that allows users to access video entertainment without a traditional video entertainment device and without the constraints of a typical static broadcasting schedule. In the 20th century, broadcasting in the form of over-the-air programming was the commonest form of media distribution. As Internet and IPTV technologies continued to develop in the 1990s, consumers began to gravitate towards non-traditional modes of content consumption, which culminated in the arrival of VOD on televisions and personal computers.[1]

Unlike broadcast television, VOD systems initially required each user to have an Internet connection with considerable bandwidth to access each system's content. When Disney, Paramount, Sony, Universal and Warner Bros. launched the Digital Cinema Initiative,[2] in 2002, the Fraunhofer Institute[3] developed the JPEG2000 codec, which enabled the distribution of movies via Digital Cinema Packages. This technology has since expanded its services from feature-film production to include broadcast television and has resulted in lower bandwidth requirements for VOD applications.

Television VOD systems can stream content, either through a traditional set-top box or through remote devices such as computers, tablets, and smartphones. VOD users can permanently download content to a device such as a computer, digital video recorder or a portable media player for continued viewing. The majority of cable and telephone company-based television providers offer VOD streaming, whereby a user selects a video program that begins to play immediately or downloading to a digital video recorder (DVR) rented or purchased from the provider, or to a PC or to a portable device for delayed viewing.

Internet television has emerged as an increasingly popular medium of VOD provision. Desktop client applications such as the Apple iCloud online content store and Smart TV apps such as Amazon Prime Video allow temporary rentals and purchases of video entertainment content. Other internet-based VOD systems provide users with access to bundles of video entertainment content rather than individual movies and shows. The most common of these systems, Netflix, Hulu, and Disney+, use a subscription model that requires users to pay a monthly fee for access to bundle of movies, television shows, and original series. In contrast, YouTube, another internet-based VOD system, uses an advertising-funded model in which users can access most of YouTube's video content free of charge but must pay a subscription fee for premium content. Some airlines offer VOD services as in-flight entertainment to passengers through video screens embedded in seats or externally provided portable media players.


Downloading and streaming VOD systems provide the user with all of the features of portable media players and DVD players. Some VOD systems store and stream programs from hard disk drives and use a memory buffer to allow the user to fast forward and rewind videos. It is possible to put video servers on local area networks; these can provide rapid responses to users. Cable companies have rolled out their own versions of VOD services through apps, allowing television access wherever there is a device that is internet capable. Cable media companies have combined VOD with live streaming services. The recentTemplate:When launches of apps from cable companies are attempts to compete with Subscription Video on Demand (SVOD) services because they lack live news and sports content.[4]Template:Clarify Streaming video servers can serve a wide community via a WAN but responsiveness may be reduced. Download VOD services are practical in homes equipped with cable modems or DSL connections. Servers for traditional cable and telco VOD services are usually placed at the cable head-end, serving a particular market and cable hubs in larger markets. In the telco world, they are placed in either the central office or a newly created location called a Video Head-End Office (VHO).Template:Cn


VOD services first appeared in the early 1990s. Until then, it was not thought possible that a television program could be squeezed into the limited telecommunication bandwidth of a copper telephone cable to provide a VOD service of acceptable quality as the required bandwidth of a digital television signal is around 200Template:NbspMbps, which is 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; discrete cosine transform (DCT) video compression and asymmetric digital subscriber line (ADSL) data transmission.[5] DCT is a lossy compression technique that was first proposed by Nasir Ahmed in 1972,[6] and was later adapted into a motion-compensated DCT algorithm for video coding standards such as the H.26x formats from 1988 onwards and the MPEG formats from 1991 onwards.[7][8] 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 100Template:Nbspkbps to 2Template:NbspMbps, while DCT compression reduced the required bandwidth of a television signal from around 200Template:NbspMbps down to 2Template:NbspMpps. The combination of DCT and ADSL technologies made it possible to practically implement VOD services at around 2Template:NbspMbps bandwidth in the 1990s.[5]

A VOD service was proposed as early as 1986 in Japan, where there were plans to develop an "Integrated Network System" service. It was not possible, however, to practically implement such a VOD service until the adoption of DCT and ADSL technologies in the early 1990s.[5] The first VOD systems used tapes as the real-time source of video streams. GTE started as a trial in 1990 with AT&T providing all components. By 1992, VOD servers were supplying previously encoded digital video from disks and DRAM.[9]

In the US, the 1982 anti-trust break-up of AT&T resulted in several smaller telephone companies nicknamed Baby Bells. Following this, the Cable Communications Policy Act of 1984 prohibited telephone companies from providing video services within their operating regions. In 1993 the National Communication and Information Infrastructure (NII) was proposed and passed by the US House and Senate, opening the way for the seven Baby Bells—Ameritech, Bell Atlantic, BellSouth, NYNEX, Pacific Telesis, Southwestern Bell, and US West—to implement VOD systems.[10] These companies and others began holding trials to set up systems for supplying video on demand over telephone and cable lines.

In November 1992, Bell Atlantic announced a VOD trial. IBM was developing a video server code-named Tiger Shark. Concurrently, Digital Equipment Corporation was developing a scalable video server configured from small-to-large for a range of video streams. Bell Atlantic selected IBM and in April 1993 the system became the first VOD over ADSL to be deployed outside the lab, serving 50 video streams.Template:Cn In June 1993, US West filed for a patent to register a proprietary system consisting of the Digital Equipment Corporation Interactive Information Server, Scientific Atlanta providing the network, and 3DO as the set-top box with video streams and other information to be deployed to 2,500 homes.Template:Cn In 1994–95, US West filed for a patent concerning the provision of VOD in several cities: 330,000 subscribers in Denver, 290,000 in Minneapolis, and 140,000 in Portland.[11] In early 1994, British Telecommunications (BT) introduced a trial VOD service in the United Kingdom. It used the DCT-based MPEG-1 and MPEG-2 video compression standards, along with ADSL technology.[5]

Many VOD trials were held with various combinations of server, network, and set-top box. Of these the primary players in the US were the telephone companies using DEC, Microsoft, Oracle, IBM, Hewlett-Packard, USA Video, nCube, SGI, and other servers. The DEC server system was the most-used in these trials.[12][13][14][15]

The DEC VOD server architecture used interactive gateways to set up video streams and other information for delivery from any of a large number of VAX servers, enabling it in 1993 to support more than 100,000 streams with full videocassette recorder (VCR)-like functionality. In 1994, it upgraded to a DEC Alpha–based computer for its VOD servers, allowing it to support more than a million users.[16] By 1994 the Oracle scalable VOD system used massively parallel processors to support from 500 to 30,000 users. The SGI system supported 4,000 users.[17] The servers connected to networks of increasing size to eventually support video stream delivery to entire cities.Template:Cn

In the UK, from September 1994, a VOD service formed a major part of the Cambridge Digital Interactive Television Trial[18] This provided video and data to 250 homes and several schools connected to the Cambridge Cable network, later part of NTL, now Virgin Media. The MPEG-1 encoded video was streamed over an ATM network from an ICL media server to set-top boxes designed by Acorn Online Media. The trial commenced at a speed of 2 Mbit/s to the home, subsequently increased to 25 Mbit/s.[19] The content was provided by the BBC and Anglia Television. Although a technical success, difficulty in sourcing content was a major issue and the project closed in 1996.Template:Cn

In 1997, Enron Corporation had entered the broadband market, constructing and purchasing thousands of miles of fiber-optic cables throughout the United States.[20][21] In 2001, Enron and Blockbuster Inc. attempted to create a 20-year deal to stream movies on demand over Enron's fiber-optic network.[22] The heavily promoted deal fell through, with Enron's share prices dropping following the announcement.[22]

In 1998, Kingston Communications became the first UK company to launch a fully commercial VOD service and the first to integrate broadcast television and Internet access through a single set-top box using IP delivery over ADSL. By 2001, Kingston Interactive TV had attracted 15,000 subscribers.[23] After several trials, Home Choice followed in 1999 but was restricted to London. After attracting 40,000 customers, they were bought by Tiscali in 2006 which was, in turn, bought by Talk Talk in 2009. Cable TV providers Telewest and NTL (now Virgin Media) launched their VOD services in the United Kingdom in 2005, competing with the leading traditional pay-TV distributor BSkyB, which responded by launching Sky by broadband, later renamed Sky Anytime on PC.[24] The service went live on 2 January 2006. Sky Anytime on PC uses a legal peer-to-peer approach based on Kontiki technology to provide very-high-capacity multi-point downloads of the video content. Instead of the video content all being downloaded from Sky's servers, the content comes from multiple users of the system who have already downloaded the content. Other UK television broadcasters implemented their own versions of the same technology, such as the BBC's iPlayer, which was launched on 25 December 2007, and Channel 4's 4oD (4 on Demand), which was launched in late 2006. Another example of online video publishers using legal peer-to-peer technology is based on Giraffic technology, which was launched in early 2011, with large online VOD publishers such as US-based VEOH and UK based Craze's Online Movies Box movie rental service.Template:Cn

The BBC, ITV and Channel 4 planned to launch a joint platform provisionally called Kangaroo in 2008.[25] This was abandoned in 2009 following complaints, which were investigated by the Competition Commission. In that same year, the assets of the now-defunct Kangaroo project were acquired by Arqiva,[26] who used the technology to launch the SeeSaw service in February 2010.[27] A year later, however, SeeSaw was shut down due to a lack of funding.[28]


Some VOD services require the viewer to have a TV set-top box. This photo shows the set-top box for the Jazzbox VOD service and its accompanying remote control.

VOD services are now available in all parts of the United States, which has the highest global take-up rate of VOD.[29] In 2010, 80% of American Internet users had watched video online,[30] and 42% of mobile users who downloaded video preferred apps to a normal browser.[31] Streaming VOD systems are available on desktop and mobile platforms from cable providers (in tandem with cable modem technology). They use the large downstream bandwidth present on their cable systems to deliver movies and television shows to end-users. These viewers can typically pause, fast-forward, and rewind VOD movies due to the low latency and random-access nature of cable technology. The large distribution of a single signal makes streaming VOD impractical for most satellite television systems. Both EchoStar/Dish Network and DirecTV offer VOD programming to PVR-owning subscribers of their satellite TV service. In Demand is a cable VOD service that also offers pay-per-view. Once the programs have been downloaded onto a user's PVR, he or she can watch, play, pause, and seek at their convenience. VOD is also common in expensive hotels.

According to the European Audiovisual Observatory, 142 paying VOD services were operational in Europe at the end of 2006. The number increased to 650 by 2009.[32] At the 2010 Consumer Electronics Show in Las Vegas, Nevada, Sezmi CEO Buno Pati and president Phil Wiser showed a set-top box with a one-terabyte hard drive that could be used for video-on-demand services previously offered through cable television and broadband. A movie, for example, could be sent out once using a broadcast signal rather than numerous times over cable or fiber-optic lines, and this would not involve the expense of adding many miles of lines. Sezmi planned to lease part of the broadcast spectrum to offer a subscription service that National Association of Broadcasters President Gordon H. Smith said would provide a superior picture to that of cable or satellite at a lower cost.[33]

Developing VOD requires extensive negotiations to identify a financial model that would serve both content creators and cable providers while providing desirable content for viewers at an acceptable price point. Key factors identified for determining the economic viability of the VOD model include VOD movie buy-rates and setting Hollywood and cable operator revenue splits.[34] Cable providers offered VOD as part of digital subscription packages, which by 2005 primarily allowed cable subscribers to only access an on-demand version of the content that was already provided in the linear traditional broadcasting distribution. These on-demand packages sometimes include extras and bonus footage in addition to the regular content.[35]

Role of peer-to-peer file sharing[]

Peer-to-peer (P2P) file-sharing software allows the distribution of content without the linear costs associated with centralized streaming media. This innovation proved it is technically possible to offer the consumer potentially every film ever made, and the popularity and ease of use of such services may have motivated the rise of centralized video-on-demand services. Some services such as Spotify[36] use peer-to-peer distribution to better scale their platforms. Netflix is considering switching to a P2P model[37] to cope with net neutrality problems from downstream providers.



Transactional video on demand (TVOD) is a distribution method by which customers pay for each piece of video-on-demand content.[38] For example, a customer would pay a fee for each movie or TV show that they watch. TVOD has two sub-categories: electronic sell-through (EST), by which customers can permanently access a piece of content once purchased via the Internet; and download to rent (DTR), by which customers can access the content for a limited time upon renting.[38][39] Examples of TVOD services include Apple iTunes online store and Google Play service.

Catch-up TV[]

A growing number of television stations offer "catch-up TV" as a way for viewers to watch programs though their VOD services after the original television broadcast. Some studies show catch-up television is starting to represent a large amount of the views and hours watched and that users tend to watch catch up TV programs for longer when compared to live television watching.Template:Cn

Subscription models[]

Template:Update section

File:The Great. Courses Plus - App Screen Shot.jpg

A screenshot of "The Great Courses Plus", a subscription video on-demand service offered by The Teaching Company that offers instructional videos.

Subscription VOD (SVOD) services use a subscription business model in which subscribers are charged a regular fee to access unlimited programs. Examples of these services include Netflix, Amazon Prime Video, Disney+ and Hulu.

Near video on demand[]

Template:Globalize section Near video on demand (NVOD) is a pay-per-view consumer video technique used by multi-channel broadcasters using high-bandwidth distribution mechanisms such as satellite and cable television. Multiple copies of a program are broadcast at short time intervals (typically 10–20 minutes) on linear channels providing convenience for viewers, who can watch the program without needing to tune in at the only scheduled point in time.Template:Cn A viewer may only have to wait a few minutes before the next time a movie will be programmed. This form is bandwidth-intensive and is generally provided by large operators with a great deal of redundant capacity and has been reduced in popularity as video on demand is implemented.Template:Cn

Only the satellite services DirecTV and Dish Network continue to provide NVOD services, which provide them due to a lack of broadband Internet access for their rural customer bases.Template:Cn Before the rise of VOD, the cable pay-per-view provider In Demand provided up to 40 channels in 2002, with several films receiving four channels on a staggered schedule to provide the NVOD experience for viewers.[40] As of 2018, most cable pay-per-view channels now number mainly 3-5, and are used for live ring sports events (boxing and professional wrestling) and concerts. In Australia, pay-TV broadcaster Foxtel offers NVOD for new-release movies.[41]

Push video on demand[]

Push video on demand is so-named because the provider "pushes" the content out to the viewer's set-top box without the viewer having requested the content. This technique is used by several broadcasters on systems that lack the connectivity and bandwidth to provide true "streaming" video on demand.Template:Cn Push VOD is also used by broadcasters that want to optimize their video streaming infrastructures by pre-loading the most popular contents to the consumers' set-top device. If the consumer requests one of these films, it is already loaded on her or his DVR. A push VOD system uses a personal video recorder (PVR) to store a selection of content, often transmitted in spare capacity overnight or all day long at low bandwidth. Users can watch the downloaded content at the time they desire, immediately and without any buffering issues. Push VOD depends on the viewer recording content so choices can be limited.[42]

Advertising video on demand[]

Advertising video on demand uses an advertising-based revenue model. This allows companies that advertise on broadcast and cable channels to reach people who watch shows using VOD. This model also allows people to watch content without paying subscription fees. Hulu was a major AVOD companies but the company ended its free service in August 2016, which was transferred to Yahoo! View using the existing Hulu infrastructure. Sony Crackle has introduced a series of advertisements for the same company that ties into the content is being watched.[43][44]

Ad-Supported Video on Demand (ASVOD) refers to video services that provide free content supported by advertisements.[45] Popular services include PLUTO TV, the ROKU Channel, Sony Crackle, TUBI, Vudu, and YouTube.[46] Walmart is adding ASVOD original programming to Vudu, and YouTube Originals will be ASVOD by 2020.[47]

See also[]


  • BitTorrent
  • Comparison of video hosting services
  • Direct-to-video
  • Electronic sell-through
  • Music on demand


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Further reading[]