Video On Demand

Video On Demand

VOD systems are systems which allow users to select and watch video content over a network as part of an interactive television system. VOD systems are either "streaming", in which viewing can start as the video streams over the Internet (or other network), or "download", in which the program is brought in its entirety to a set-top box before viewing starts.

All download and some streaming video on demand systems allow the user to pause, fast forward, fast rewind, slow forward, slow rewind, jump to previous/future frame etc. In other words to provide a large subset of VCR functionality. For streaming systems this requires more effort on the part of the server, and may also require greater network bandwidth.

It is possible to put video servers on LANs, in which case they can provide very rapid response to users. Streaming video servers can also serve a wider community via a WAN, in which case the responsiveness may be reduced. Nevertheless, it is possible to provide streaming VOD services over a wide area network. Download VOD services are practical to homes equipped with cable modems or DSL lines.

The first commercial VOD service took place in Hong Kong around 1990. The technology was not mature, Video CDs were much cheaper, and pay TV was not common in Hong Kong. Hong Kong Telecom lost a large amount of money and the service was shut down after it was acquired by Pacific Century Cyberworks in 2000.

VOD services are now available in all parts of the USA. Streaming VOD systems are available from cable providers (similar to cable modem technology) who use the large downstream bandwidth present on cable systems to deliver movies and television shows. Users 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 TV systems; however, EchoStar recently announced a plan to offer video on demand programming to PVR-owning subscribers of its DISH Network satellite TV service. The programs are automatically recorded on the PVR, then the users can watch, play, pause, and seek at their convenience. VOD is also quite common in more expensive hotels. Internet download VOD systems are widely available.

It is possible to implement VOD using methods such as bandwidth skimming, which can deliver O(log n) scaling as the number of users increase.

Near Video on Demand
Near Video on Demand (NVOD) is an 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 programme are broadcast at short time intervals (typically 10–20 minutes) providing convenience for viewers, who can watch the programme without needing to tune in at a scheduled point in time.
This form of broadcasting uses large amounts of bandwidth and is only viable for operators with large amounts of spare capacity.

Video on Demand Providers
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Comcast has a video-on-demand service in the US.
Time Warner Cable has a video-on-demand service in the US.
Cox Communications has deployed video-on-demand service in several of its US locations.

Charter Communications offers a video-on-demand service in most of its US markets.
HomeChoice has a video-on-demand service in the London area of the UK.
Rogers Cable and Shaw Communications have video-on-demand service in Canada.
MovieBeam a video-on-demand service by Disney.
Movielink a video-on-demand service that provides movies for download to desktop and laptop PCs.
CinemaNow a video-on-demand service that provides movies for download to desktop and laptop PCs (including titles in High Defnition 720p/5.1).
NTL in the UK has a Video on Demand service on Digital cable in their Glasgow, Swansea, Cardiff, Luton and Nottingham franchise areas.
Cablevision has IO Digital Cable a video-on-demand service in the US.
TransACT services parts of Canberra (Australia)
Akimbo is a broadband internet based video-on-demand service that delivers standard definition video content to televisions in the US and Canada.
Síminn provides video-on-demand service in Iceland.