Video on demand (VoD) is a technology that enables users to select a video (or a movie) from a large collection, while sitting at home, and have almost the same control over its viewing as while using a DVD (or a conventional VCR). With VoD, one can watch a film of their choice, rewind and then watch it again as many times as they want.

Based on the broadcasting technology used, Video-on-demand can be divided into two categories:

Centralized broadcasting approach: In this approach, the server is responsible for data access and storage and data transfer. The client on the other hand is responsible for decoding and playing the video. The rest of the application logic may reside at the client or the server or be divided between the two.

Non-centralized broadcasting approach: In this approach, there is no distinction between server and client and the client actively participates in sending videos to other clients. Mostly solutions based on peer-to-peer networks are used. Peer-to-peer networks enable peers to collaborate without the need of a centralized component.

Nowadays combinations of these two systems have emerged, that have servers but use clients to help reduce the bandwidth requirement of the server. These systems are referred to as hybrid systems.

Types of video on demand services: Video on demand services can be classified into several categories:

1. Near video on demand (N-VoD) is a pay-per-view consumer video technique used by multi-channel broadcasters using high-bandwidth distribution mechanisms such as satellite and cable television. A number of movies are broadcast at short time intervals (typically 15-30 minutes) providing convenience for viewers, who can watch the movies without needing to tune in at a scheduled point of time.

2. Push video on demand (P-VoD) service is a technique for the broadcasters whose systems lack in the interactivity to provide true video on demand. A P-VoD features a Personal Video Recorder that can automatically record a selection of programs for the user. The user can then watch the downloaded programs at his convenience. As the content is recorded on the hard-drive, downloaded content is usually deleted after a fixed interval of time to make way for new programs.

3. True video on demand (T-VoD) services offer the user complete control over the session presentation. The user has full-function VCR (virtual VCR) capabilities, including forward and reverse play, freeze, and random positioning. T-VoD needs only a single channel per customer; multiple channels become redundant.

Some of the benefits of video on demand are:

• It gives subscribers the flexibility they are looking for in watching movies in their leisure time.

• It gives customers the freedom and control over what they watch and when, as they get access to the large online content library.

• The quality of picture and sound (in VoD) is much better as it is 100 percent digital quality.

• Improved security of resources.

Low cost content distribution.

Better revenue generation for the provider.

XStream - NVoD playout system

XStream gives subscribers the flexibility they are looking for in watching movies in their leisure time while service providers freely manage their own pay-per-view and near video-on-demand (NVoD) programming with the NVoD system from RTPL. RTPL has earned a good reputation by bringing the television industry the ideal balance of power, reliability, stability, and affordability.

The XStream NVoD system is no exception for exceptional performance, scalability, and the high fault-resilience in the industry. The system supports up to 32 standard or high-definition (SD or HD) channels simultaneously via ASI or IP outputs carrying MPEG-2/MPEG-4 video. The server then generates live transport streams (DVB), and provides advanced multiplexing and PSI/SI management functions. The result is a DVB compliant transport stream that can be used directly, without any post processing.

The system is operational at, Manthan Broadband Services, Kolkata, Intermedia Cable Communication (ICC) Network, Pune, 7 Star Digital Network, Mumbai, and Home Cable, Mumbai.