What is an Interactive TV Decoder?
An interactive TV decoder is a device that enables a
set top box connected to a digital TV network, to deliver
both digital TV programming and information services to a
TV set. The basic functions performed by an interactive TV
decoder include identifying and filtering specific programs
embedded in a compressed digital TV data stream, and
capabilities. Conexant’s interactive TV decoders offer CPU and
graphics performance ideally suited for such mid-range interactive
TV set top boxes, in which a system can be implemented using
8 MB or 16 MB of SDRAM, depending on the functionality desired.
Conexant’s powerful video/graphics display compositing engine
supports up to six independent image planes to enable the
rich visual interface required for simultaneous TV viewing and
application interaction. In addition, Conexant’s 2D graphics
rendering engine can composite an unlimited number of graphics
planes with transparency into a single displayable OSD plane.
decompressing the video and audio data associated with
the selected program. This generates the TV program’s
picture and sound. An interactive TV decoder can also
identify and filter information sent in the digital TV data
stream. Data pertaining to interactive applications is
processed by the interactive TV decoder’s embedded CPU
under OS control, and generates a graphical user interface
that can be navigated using the set top box’s remote
control unit.
More advanced interactive systems on high-bandwidth cable
networks go even further. They offer full Internet access,
including Web browsing, e-mail and chat applications.
Conexant’s architecture scales up to satisfy the requirements of
this computer-centric set top box model with a high-performance,
133 MHz, 32-bit SDRAM memory controller and a 160 MHz,
32-bit CPU providing 160 MIPS dedicated to OS and
application execution.
a variety of video/graphics image scaling, filtering and
blending techniques. The interactive TV decoder must also
provide a return channel data communications mechanism
The interactive TV decoder’s graphics-controller function
allows both the TV picture and application user interface
graphics to be presented as a single image on the TV, using
A high-performance 2D graphics rendering engine accelerates
8/16/32bpp graphics screen updates to support multiple
overlapping graphics screen surfaces. The display-compositing
engine enables picture-in-graphics, flicker filtering, alpha
blending and other effects. The CX22490 supports direct
attachment to an IDE hard disk drive for video pause and
Web-browser caching applications.
decrypt TV program and application content which has
been encrypted by the service provider to protect against
unauthorized access to services. Support for this kind
of conditional-access system is usually implemented via
smart card technology, combined with an embedded
decryption circuit.
to allow the application to interact with the broadcast data
source. This is typically done via a telco or cable modem.
Finally, the interactive TV decoder should be able to
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