|
Satellite
& Cable
October
30, 2002
Digital STB decision and your interactive business
Digital pay TV offers broadcasters the potential
to generate additional revenue by introducing interactive
and enhanced TV services Programming content remains
a critical part of the service to viewers. But the issue
of selecting the set-top box (STB) is the deciding factor
that will significantly influence the type of interactive
services that can be offered and the future revenue
potential of the broadcast operation.
A
balance between the performance and the cost has to
be achieved. This is influenced by the choice of software
and hardware in the STB and plans for future interactive
and enhanced TV services. Market conditions require
affordable STBs with high performance. Let us look at
the different types of interactive TV services and their
impact on STB hardware and software selection.
CHINA
-- Choosing the right STB for digital pay TV is a complex
decision, which a broadcaster has to make carefully.
It is even more important for a broadcaster planning
to generate additional revenue by offering interactive
TV services. The STB is designed to receive the TV signal,
run the interactive applications and pass them on to
the TV. Its hardware and software depends on the nature
of those signals and applications.
Each
broadcaster follows a set of standards that help define
what those signals look like. The most basic and commonly
used is the MPEG-2 compression standard that allows
you to broadcast highly compressed digital signals.
Digital video broadcast (DVB) standards define the transmission
format and describe the video and audio signals.
The
ways in which the interactive applications are delivered
to the STB are different among the different middleware
vendors. However, there is a growing trend to use HTML
and XML as the language to author and display interactive
services. This would enable developing applications
by using the widely available Internet tools and draw
on the large number of programmers with Web development
skills.
Basic
components of STBs
The STB is a specialised computer designed for TV. Its
basic components include:
Computing
subsystem: It that handles the basic computing functions
and includes standard computer components like CPU,
memory and modems.
TV subsystem: It understands and processes TV signals
specifically and includes MPEG-2 processing capability
and video/audio output to a TV or a video recorder.
Conditional access subsystem: It permits or denies
permission to view programs based on viewer entitlements
and includes the smart card and descrambling hardware
as well.
The
STB software is made up of several distinct layers:
Hardware drivers: That interfaces between software
and hardware and is provided by STB vendors.
Core software: That provides the software platform
for applications running on the STB. The category includes
the operating system, boot loader, TV core, middleware
and conditional access.
Applications: These perform functions that the viewers
need, from the electronic program guide (EPG) to the
variety of interactive TV applications.
Significance
of interactive TV apps
The STB is the interface between the network and the
viewer in a digital video-broadcasting network. It is
also the vehicle to run several applications, such as
the EPG, and interactive and enhanced TV applications.
As the popularity of interactive services grows among
viewers, so will the opportunity to generate revenue
for broadcasters. Hence, the STB should have the capacity
to support an increasing number of interactive applications,
each with unique software and hardware requirements.
In general, interactive TV applications can be summarized
into the following four categories:
One-way
interactive applications: Such applications may include
weather reports, traffic reports, news headlines, sports
statistics, sports news, games, viewer quizzes, local
events calendar and schedules, and financial news and
information. In one-way interactive applications, a
broadcaster bundles and transmits the information in
the proper format and structure to the STB using a high-bandwidth
digital channel. Subscribers will access the information
interactively using their remote control.
Two-way
interactive applications: Such applications have all
the functions of the one-way interactive applications.
In addition, two-way interactive applications allow
two-way communication between the viewers and the broadcaster.
Viewers can send responses, feedback and even transaction
information to a broadcaster via the broadcast system's
return path. Some typical two-way interactive applications
include online betting, home banking, home shopping,
share trading, and event ticket purchasing.
One-way
messaging applications: Such applications establish
an efficient way for the broadcaster to convey information
to viewers. Such information can include emergency alerts,
program promotional messages and bulk mail messages
from the broadcaster. One-way messaging can also be
broadcasted to group users and unicasted to selected
viewers.
Two-way
messaging applications: Such applications require minimal
interaction with home viewers. A viewer is asked to
respond to a simple message that appears on the screen.
The viewer's response can be reported to the headend.
Some typical two-way messaging applications include
polling, lotteries, quizzes and interactive advertising.
Killer
characteristics of interactive apps
Interactive applications can range from the simplest
one-way on screen display messaging system, to the most
complicated home banking or home shopping real-time
transaction services. To attract more viewers, these
applications need some technical killer characteristics
to make them more engaging and entertaining. These technical
capabilities are very important considerations for planning
the broadcast network and the STB. These are some of
the most important 'killer characteristics,' that we
feel will be the most important in the next two to three
years:
-
High-quality
video, audio and graphics with more scalable fonts.
These characteristics influence the interface and
are key differentiators for viewers interacting
with the service. Ability to synchronise the interactive
service with the programming content. For example,
with a TV shopping service, if the interactive service
is synchronised with the live programming, viewers
will be able to see an item on display and push
a button to instantly buy that item. It will make
the application dynamic and an integrated part of
the real-time programming offering.
-
Live
video window within the data and information services
to provide viewers a more dynamic service. For example,
if a viewer is watching a documentary, they could
activate the interactive option and then watch live
programming in scalable video window while simultaneously
viewing the on-screen display of data or information
relating directly to the content of the programming.
-
Addressability
or the capability of the application to address
the individual subscriber according to his or her
demographic information. This will give a broadcaster
the ability to customize messages for individual
viewers, and open new opportunities for viewer feedback,
direct mail messaging, and targeted interactive
advertising.
-
Return
path capability. Previously broadcasting was a vehicle
for one-to-many transmission. With developments
in interactive TV, a viewer is able to provide feeedback,
request information or buy goods through their TV.
The return path is required for systems with this
advanced functionality.
All
of these characteristics need support from the STB.
We will now analyse the impact of all these requirements
on the STB.
Impact
of interactive apps on STB hardware
As mentioned earlier, interactive TV can offer several
exciting services. However, each one of these services
poses different requirements for the STB hardware.
A broadcaster normally introduces interactive services
gradually and over a time period, from the more simple
to the more complex viewer navigation and operation.
The STB is a consumer device that will be used in the
home for a very long time. However, the model of upgrading
hardware as seen in the PC market cannot be realistically
implemented. A broadcaster has to ensure that the STB
initially deployed in the market can perform satisfactorily
even after several years, while running an increasing
number of interactive applications.
The most affected part of the STB hardware is the computing
subsystem. The central processing unit (CPU), the brain
of any computer, is the main processor that runs the
software in the STB. It has to be powerful enough to
handle the applications.
The
experience of not having enough computational power
in the PC world is now repeating itself in the STB.
Applications are getting increasingly complicated and
graphics are getting richer. The CPU's performance is
the key to adding functionality to the box. The faster
the CPU, the easier it is to add functions such as browsing
and interactivity to the box.
More
memory future proofs STBs
A few interactive services mentioned earlier require
multiple planes of graphical capability. It is certain
the applications in the future, for example games, will
require increasing amounts of computational and graphical
power. Apart from the CPU, memory is another deciding
factor to the STB's performance. There are many types
of memory used in the STB for storing software, character
fonts, buffering video and other uses. Identical to
the PC, more memory means more performance and added
future proofing for the STB.
A large amount of memory is used in STBs to hold the
programs that handle the digital services. Storage is
also required for supporting character-based languages
such as, Chinese, Korean and Japanese. In the past,
read-only memory (ROM) was often used for this purpose.
Today, ROM is being replaced in almost all of the STBs
by the more flexible flash memory. Its major advantage
is the fact that most of it can be erased and reprogrammed
with new software delivered through the broadcast stream.
Flash memory is suitable for the main software that
resides and runs the STB, rather than transient applications
that change depending on which TV channel the viewer
is currently watching and which interactive service
is selected. Some of applications are best stored in
the STB, such as the electronic program guide. Another
type of memory is the dynamic random access memory (DRAM),
which is used in the STB for data storage and decoding
video/graphics.
The CPU uses the DRAM to execute its software and for
information needed by a current application. A DRAM
can hold a few days' worth of program guides for TV
viewing. For interactive applications, it stores the
application itself that is downloaded from the stream,
and the data required for running the application.
An interesting way to make the STB work faster is to
store the main software on the flash, but to run it
from a copy in RAM. It is important for a broadcaster
to specify some extra DRAM space while possible, which
can give better performance while running more complex,
interactive applications. It also provides a possibility
that additional applications in future may still run
on this same STB.
The video DRAM is used in the STB for decoding and storing
the video/graphics image that is being output to the
TV or a video recorder. The amount of video DRAM required
depends almost totally on the picture's video resolution.
There is an increasing trend that the DRAM and the video
DRAM are shared in the STB.
The
natures of interactive applications require very rich
graphical contents. The number of graphics planes supported
determines how the STB will be able to put text and/or
graphic bitmap overlays over the TV picture, and how
many different layers can be supported.
Impact
of interactive apps on STB software
Once the right hardware is in place, the choice of middleware
is the next most important decision that the broadcaster
has to make. The middleware or virtual machine might
be generically called 'the application portability layer.'
It provides a level of abstraction from the hardware
that gives application developers access to all features
and functions of the STB and of network data, but without
being tied to the specific hardware application. This
enables the STB to run a variety of applications, including
unknown ones that would be written in the future.
The
variety of different middleware approaches makes it
particularly hard to choose the right one. What are
the issues that you should consider when making this
decision?
-
First
and most important, does it provide the feature
set that you need? You probably know which interactive
applications you want now and have a good idea of
what you will want in the near future. Does this
middleware support the features you will need for
these applications?
-
How
many different applications are available? Is the
middleware and its applications integrated with
the conditional access that you want?
-
Does
it support the languages used in your market? Is
it capable of supporting scalable fonts that will
be required for interactive applications?
-
Is
it ready when you need it? One of the most important
issues for you is time to market for your service.
You need a middleware that can provide the right
functionality at the right time.
Whatever
the middleware choice, it is important to make sure
that the middleware selected can support the download
of the middleware later. It will enable you to launch
with one solution and migrate over time to newer versions
of that middleware, or even to other middleware products.
The
latest STB technologies offer a broadcaster many choices
to provide exciting interactive services and generate
revenue. The selection of STB technologies is one of
the most important decisions the broadcaster has to
make. The broadcaster has to make sure that STB selected
will enable it to offer latest applications to its box
population. Investment in the STB will affect the broadcaster's
business for years. To succeed, it has to make sure
that the decision made will stand the test of time.
The
author is from NDS' Beijing representative office.
Contact:
NDS Group plc
One London Road
Staines
Middlesex TW18 4EX
United Kingdom
Tel: +44 (0)20 8476 8000
Fax: +44 (0)20 8476 8100
Web: www.nds.com
|
