Video On Demand service providing interactive access to specific material at the request of an individual user.
A true Video On Demand or VOD service allows the user to select from a range of programming stored on a remote server and enables user control of the selected stream in a similar manner to a video recorder, including pause and rewind.
This is particularly suited to interactive digital cable services, but is also possible over broadband networks. Such services are suited to premium subscription material, although the cost of providing such services is falling and they are becoming more prevalent.
An alternative, known as Near Video on Demand or NVOD, allows the user to select from a smaller range of programming and provides the impression of video on demand. This approach is typically adopted by satellite broadcasters.
Often used for feature film material, this may involve broadcasting a programme on more than one channel with staggered start times to allow the user to join the start of a programme at a convenient time. The interval between start times may be filled with promotional material. In this case the user does not have the ability to directly control the programme, although pause and rewind may be available to viewers with the digital video recording facilities of a PVR.
A variation of this approach, typically used for shorter clips of material and particularly suited to information services, involves continuously looping material designed to allow the user to join at any point. This may be combined with a mosaic screen that allows the user to select a particular clip, offering the impression of access on demand.