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One can walk into a vegetarian restaurant but cannot order meat or chicken
dishes. The present scenario in television is similar. ‘Dumb’ viewer accepts
what is offered. If a farmer, watching a TV program on, say, use of manure,
wants clarifi-cation online on the quantity and frequency of use for a
parti-cular type of crop, it is not possible. One cannot interact on TV. One can
reach back to broadcaster only through primitive communication for feedback. Use
of telephone line causes delay or may find a dead end.
One watching a TV program likes to choose what one wants. Dr A Pandian,
Strategic Initia-tive Group, Wipro Technolo-gies, feels, "Ideal model is
that the ‘viewser’–as he prefers to call viewer-user–uses Intera-ctive
TV or iTV, buys the Set Top Box (STB) from any shop and chooses any service
provider." iTV is a domestic television with interactive facilities and an
e-back channel. He compares the computer business as having matured to a higher
level. iTV is Digital interactive TV or Digi TV.
iTV is a way to empower vie-wser to use TV in new ways. These ranges from
accessing the Web, Internet, home shop-ping, digital video broadca-sting, movie
on demand and video telephony. TV is central to this new social life. Some
typical applications include - TV mail (similar to e-mail), TV chat, TV
commerce, TV interactive games, Video on Demand (VOD), Personal Video Recorder (PVR),
Electronic Program Guide (EPG) and TV education. Only imagination and creativity
limit more application.
iTV content can either be created using authoring tools or is downloaded from
the Inte-rnet. It will have data apart from audio and video. Data consists of
two parts, infor-mation (variables) and execu-tion code. Execution code gets
loaded and executed along with the video and audio dis-played on the TV. Each
segment of interactive content contains a piece of execution code and
information. Request from the viewser rides back an execution code.
In iTV, advertised products get response. For example, an advertisement on TV
gets loa-ded with the corresponding execution code to process vie-wser request.
The Viewser request is captured and sent to the back end server. The back end
server will process the request and transact the order. Thus data captured by
the TV/STB is sent to the content ser-ver. Based on the application and the
request, the server responds. Finally the product can be delivered to the
door-step of the viewser.
Digi TV has certain beneficial features. With 400 percent compression, more
channels are transmitted or alternatively, use of entire channel results in high
quality video. The 5.1 Dol-by/AC-3 audio with two-chan-nel stereo, two-channel
surrou-nding, center and woofer chan-nel, offers theatrical quality of sound.
From as less a resolution of 486 x 720 pixels reaching up to a high of 1080 x
1920 pixels, it promises finer details of picture with true color.
There are two approaches to implement the Digi TV - (1) STB centric and (2)
Head-end centric architectures. STB can be ‘thin’, but then, head-end is to
be powerful and complex enough to support many thin STBs and still deliver
quality service. When complexity is shifted to the STB, it becomes ‘thick’
and the complexity of head-end gets reduced. The pricing strategy also shifts
accordingly. New rules may be needed. The imbroglio in STB for cable TV and
limited mobility telephone is a fore warning to India.
STB centric architecture of Digi TV with interactivity
The content is stored in a database at the back end. Based on the program,
the content is accessed from the database and converted to an encrypted,
compressed stream, which is then multiplexed with the conditional access
information. The multiplexed data is trans-mitted through a medium - satellite,
cable, Digital Subs-criber Link (DSL) or terrestrial. The cable service provider
will capture the signal through satellite or terrestrial link.
The signal is received by the STB/TV usually from cable
connectivity. STB gets inputs either from the keyboard, rem-ote control or from
the smart card to enable the conditional access. After verification with the
access rights, the content is displayed on the TV.
Head-end centric archite-cture of Digi TV has cost-benefit
advantage over a STB centric solution. Technology involved is complex. More
resources are located in the cable head-end and iTV services are delivered to
any TV set that supports Moving Picture Experts Group, MPEG. Such resources must
be integrated into every thin STB.
Digi TV will co-exist with the existing analogue system till
it is phased out. Of one billion TV installations, analysts predict 625 million
Digi TV by 2005 ris-ing from 40 m in Y2K. Consu-mer Electronics Association (CEA)
and National Association of Broadcasters (NAB) are pushing for Digi TV. Rules to
forbid copying and redistri-buting Digi TV program on Internet are underway. The
new rules may not affect cable and satellite TV using programmed encryption.
Choosing the standard for a particular country depends on the
existing analog TV stan-dard, government policy and the existing transmission
network. There is no standar-dization of STB and services. In India, STB is now
implemented only in Chennai. It is a forerun-ner–in nomenclature and not in
hardware technology - to iTV. Presently, the network opera-tors decide the
specifications of the STB for the service one provides. In turn, perhaps, a
manufacturer of the devices is influenced by the operator to decide the chip
sets, Operating System and the middle ware that will go into the technology.
Drawbacks of Digi TV:
-
The existing TV is analog and does not handle the digital
signal -
STB to convert digital signal to analog is required,
adding cost to the subscriber -
Due to insufficient pixel density and less bandwidth in
the amplifiers, analog TV with STB will not reproduce true HDTV performance -
However performance will be better than the analog TV
without STB -
Due to small size pixels, TV brightness reduces–needs
specially designed TV CRT to increase brightness, raising cost of Digi TV
supporting HDTV.