Video on demand

Video on demand (VOD) is a media distribution system that allows users to access videos, television shows and films digitally on request. These multimedia are accessed without a traditional video playback device and a typical static broadcasting schedule, which was popular under traditional broadcast programming, instead involving newer modes of content consumption that have risen as Internet and IPTV technologies have become prominent, and culminated in the arrival of VOD and over-the-top (OTT) media services on televisions and personal computers.

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 may also permanently download content to a device such as a computer, digital video recorder (DVR) 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 programme that begins to play immediately (i.e., streaming), or downloading to a DVR rented or purchased from the provider, or to a PC or to a portable device for deferred viewing.

Streaming media has emerged as an increasingly popular medium of VOD provision over downloading, including BitTorrent. Desktop client applications such as the Apple iTunes 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, Disney+, Peacock, HBO Max and Paramount+, use a subscription model that requires users to pay a monthly fee for access to a selection 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 its 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 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 early-2020s launches of apps from cable companies (e.g., NBC's Peacock, CBS's Paramount+) are attempts to compete with subscription video on demand (SVOD) services because they lack live news and sports content.^{[clarification needed]} 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).^{[citation needed]}

VOD services first appeared in the early 1990s. Until then, 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 VOD service of acceptable quality as the required bandwidth of a digital television signal is around 200 Mbps, 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: MPEG (motion-compensated DCT) video compression and asymmetric digital subscriber line (ADSL) data transmission.

Plans such as those of the Integrated Network System, a national high-capacity fibre-optic network supporting a range of broadband services in Japan, noted in a more general 1986 publication, were interpreted as conducive to eventual VOD deployment. However, early VOD trials employed existing cable television infrastructure, notably British Telecom's video library trial, operated through the Westminster Cable Company. This trial used the Laservision media format and featured a jukebox-like media handling system involving players served by disc carousels, with twelve such handler units capable of serving up to 6,000 customers. Other early 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.

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. These companies and others began holding trials to set up systems for supplying video on demand over telephone and cable lines.