Video-on-demand (VOD): Hot chase to Broad casters

Why feel sorry for missing some scheduled programme?

It looks very pathetic for the parents to put off their wards’ demand for some specific programme on television at odd hours. They do not have any excuse to suit his/her choice. With the advent of “on demand” services a new taste of marketing has evolved. Be it cable Telephony’s fax-on-demand or cable operators Video-on-demand, there is always some choice to make a hole in the broadcaster’s den. Video-on-demand has aroused the familiar mixture of hype and disillusion. The idea of innovation that gave birth to this technology is watching a favourite movie or TV programme when you want to watch rather than when the schedule say-without the need to trek to the video shop.

How the Technology works?

Video-on-Demand gives the subscribers the option of watching any movie at any time. In other words dedicated channel service for every subscribers for almost every programme. Recent interactive technology has added glamour to this service by providing telephone on the same line while watching the film on TV.

There are basically two types of systems that give this facility Video-on-demand or Video dial tone (VDT) and Cable on demand. In the Video-on-demand or Video dial tone (VoD or VDT), digitally compressed Video signals are sent using telephone lines and a converter box at the subscriber’s home, wherein the subscriber can fast forward or even rewind the film as he wishes. This way it is similar to an on-line VCR/VCP service. The converter at subscriber’s home converts the digital signal into analog, stores it in momentary lines and plays it in real time. So on one line only one Video channel can be transmitted. There is a central exchange, where thousands of Videocassettes or CDs are stored. The moment a subscriber selects a movie using his TV remote, a robotic arm in the exchange selects that cassette/Compact Disc (CD) and plays it.

The entire contents of the tape are then fed into a disc drive, which can simultaneously serve 80 or more customers watching any one of the movies from the tape/disc stacker.

How ATM works?

Video on demand works on the principle of ATM technology. As projected, ATM i.e. Asynchronous Transfer Mode; is the solution for Bandwidth hungry communication uses of the future. ATM is a more flexible Version at high speeds. Here asynchronous in the term ATM means ‘ATM is asynchronous in a manner that data is passed only when required. No bandwidth is expected to be put at hold for un-utilised or little utilised services. Consequently, an efficient use of available trunk bandwidth is at hand.

ATM has the provision for managing the traffic according to the priority for consumable software.

Methodology of ATM

The ATM network aims at carrying all forms of traffic over one switching fiber based on cells. To adopt, all forms of communications to ATM cell switched structure, it is required that ATM must multiplex many different cell streams over a single line or carrier facility. This multiplexing is done with the cell address.

ATM operation is based on three basic elements:

(a) Cell structure (b) Switching technology and (c) Negotiated service connection.

The fixed size cell technology allows hardware processing i.e. hardware addressing and switching. This ultimately reduces overheads on the system and thus the maximum performance is assured.

The ATM cell size is of 53 bytes. Out of which 5 bytes are for address and signaling information and 48 bytes are for the payload. The header contains information, which tells the network where the data has to go, and what kind of data is it?

ATM can carry a variety of communication trafficking, so it must tell the network what kind of traffic it is?

ATM is not shared technology like LAN (Local Area Networking) in the UNIX system. It is designed around dedicated individual connections, because of this no one affects another.

Market spread

Market tests for the viability of pricing and reliability of services concerned to this system has shown satisfactory results. Tests such as Cambridge Trial of Digital Interactive Television set up by Acorn On-line media in the UK in 1994, show that the technology does work for fully digital, fully interactive, instantaneous, Video-on- demand. It is clear that the technology is not expensive if the volume is increased.

In U.K. and certain other countries, cable operators, offering VoD have good experience of changing behavior of price- sensitive consumers. Now they are willing to pay a premium for choice, convenience and control. The most stable character, which has remained more or less the same over the periods of transition is-viewing habits. It was seen that movie ordering was during evening Prime time and at weekends while institutional (educational/ entertainment) programmes were on demand during the daytime. 

With the Broadcasting Bill knocking the door (In Winter session of Parliament), It is expected that cable operators in India too, will get some respite through the licensing and controlling avenues to have a say in interactive broadcast. The on demand services will enter Indian citadel also and the next year will have in its stock too many services to realise the dreams which started with the privatisation of telecommunication in the country.

Near Video on Demand (NVOD)

“Near Video on Demand” system provides convenient access to a small library of popular Video material. NVOD is an extension to the impulse pay per view system, where each movie occupies several channels with staggered start times. For example, a 100 minutes movie could occupy 10 channels with a 10 minutes staggered start interval. Five movies of this average duration would require or about 400 MHz bandwidth network, this might use the spectrum from 350 MHz to 750 MHz; leaving 50 to 350 MHz spectrum for broadcast and basic service usage. The network design is simpler mainly a tree and branch architecture. This is a service involving low cost, return channel for retrieving purchase transactions from the set top converter

Video-on-Demand gives the subscribers the option of watching any movie at any time. In other words dedicated channel service for every subscribers for almost every programme. Recent interactive technology has added glamour to this service by providing telephone on the same line while watching the film on TV.

Virtual Video on Demand (VVOP)

It is a modification to NVOD, in which a playback control computer is added at the head end, which examines the previous days purchases, and adjusts the playback intervals to a popular service, down to one channel with a single repeating service every 100 minutes( on an average) for the least popular service.

Source: http://cablequest.org/articles/broadcast-technology/item/1301-video-on-demand-vod-hot-chase-to-broad-casters.htmlSource: http://cablequest.org/articles/broadcast-technology/item/1301-video-on-demand-vod-hot-chase-to-broad-casters.html