||This article needs more links to other articles to help integrate it into the encyclopedia. (November 2012)|
||This article should be divided into sections by topic, to make it more accessible. (November 2012)|
HDVSL stands for high definition video over subscriber line. HDVSL is an Indian standard which has been specifically developed to address the need for a terminal free computing experience on television type display devices such as cathode ray tube based televisions and LCD televisions. The Technology Development Board of the Government of India conferred the National Technology Day Award on 11 May 2008 on the inventor for developing and commercialising the HDVSL standard - marking the first official recognition of the Indian Government to the new standard for interactive video. The standard uses ITU's H.264 compression codec and is likely to be G.HN compatible when the G.HN standard is officially announced.
The HDVSL technology stack is very similar to a standard DSL stack with a digital subscriber line access multiplexer at the telco end and a DSL modem at the home end. However it is also deployable over legacy coaxial cable and electricity networks. The HDVSL modem does not require any kind of terminal in the home such as a PC or set top box. The modem connects to a display and input device directly. At the HDVSL Dslam end - the stack requires an application server which provides a remote computing interface for standard computing applications and interactive video services. The HDVSL Dslam generates and transports a "push video" stream to the home. The HDVSL stack is currently based on Microsoft standards compliant products - and an open source option is likely to be available soon.
India has over 2.5 million DSL subscribers, 80% of which are on the ADSL2+ standard. Indian DSL penetration has been limited by the absence of personal computers in Indian homes. Only an estimated 3 million of the 200 million Indian homes own a computer. Most government plans to increase PC penetration in recent years have failed. Reasons for failure include the cost of a PC, language, computer illiteracy etc.
HDVSL is an Indian DSL standard, which successfully addresses this problem. The HDVSL standard operates a 36 Mbit/s duplex Ethernet link - and the HDVSL modem has a direct connection to a display eliminating the need for a terminal or client altogether in the home. The HDVSL modem also acts as a set top box and DSL modem substitute for home internet connectivity on a television screen. HDVSL has an estimated 250K homes under deployment in India and China - mostly over a fourth wire - the intercom wire which is used for in-building security systems. The HDVSL standard is likely to see large scale commercialisation in 2008. In addition, there have been several startups which attempt to provide thin client and remote computing based solutions. HDVSL developers like Cheekotel have integrated the HDVSL stack into their remote computing and interactive video solutions. Cheekotel's HDVSL-compliant network can do things like get a remote operator to find something for you on the internet and then transfer the page to your PC or television, thus significantly easing the process to find relevant rich media information on the internet. This approach however has raised fears that operators like Cheekotel will build and maintain proprietary search engines which will finally have to be paid for.
The most ambitious HDVSL deployment on a tier I telco network is the videomail content delivery network (CDN) being built by NYSE listed Mahanagar Telephone Nigam Limited (MTNL) in the city of Mumbai, India. MTNL is the broadband market leader in national capital Delhi and the commercial capital Mumbai with close to one million DSL broadband subscribers. The videomail CDN in Mumbai will have a capacity of over 100 Tbit/s making it probably the most powerful CDN every deployed anywhere. The videomail CDN is being used to deliver a HD experience to HD screens in signage applications with a video return path. A British TV2.0 company is believed to be the content partner for the interactive television deployment. This CDN can do advanced rich media bandwidth hungry applications in addition to one way or full duplex video telephony.
India has also approved the construction of a HDVSL-compliant rich media data centre with an initial capacity of 28,000 video servers. The data centre is being built by the Interactivity consortium and would connect to the San Francisco to London medianet submarine cable. The Medianet submarine cable is likely to have full function landing points in Singapore Media City and Dubai Media City. Once fully operational - it will facilitate a place shift of television channels making terminal based place shift devices like slingbox obsolete.
Chinese taxis 
China's largest taxi operator will commence trials of a HDVSL based "in cab" television service which plays location specific content and advertisements. As an example, when the taxi is about to approach a famous landmark - a video related to that landmark plays on a 9" screen in the taxi. The HDVSL terminal also provides an audio return path to enable the taxi passenger to access a translation service which can help instruct the taxi driver. A large pilot project was tested during the Canton fair in 2008 with excellent results.