lnteractive TV Decoders
Single-Chip Interactive TV Solutions
Conexant’s interactive TV decoder products provide complete
system solutions for the core electronics of high-performance set top
boxes deployed in digital satellite, cable or terrestrial TV networks.
The CX22490 and CX22496 offer an advanced, embedded 32-bit RISC
CPU, an MPEG-2 audio/video decoder and 2D graphics performance.
This combination enables consumer electronics manufacturers to
build low-cost digital TV set top boxes to support a wide range of
advanced, interactive, consumer entertainment services.
Distinguishing Features
CX22490/22496-based set top box system
The CX22490 and CX22491 combine an [email protected] MPEG-2 video
decoder, a digital audio decoder, a programmable MPEG-2/DVB/
ATSC/DSS transport stream demultiplexer, a high-speed 2D graphics
rendering engine, and an advanced display compositing engine with
a high-performance, embedded 32-bit 175 MIPS ARM940T RISC
processor and integrated peripheral I/O ports. These secondgeneration interactive TV decoders share a common core feature
set. The CX22490 adds USB and IDE multiword DMA support to the
core features, while the CX22496 adds NDS CA hardware support.
• MPEG-2 A/V decoding, Dolby Digital decoding
• Dedicated RISC-based transport
stream processor
• High-performance 32-bit 175 MIPS integrated
• High-performance 2D graphics
rendering acceleration
• Multiplane video/graphics compositing
and display engine
• High-performance unified memory
controller architecture
• Full suite of set top peripheral I/O
interface controllers
lnteractive TV Decoders
Fast CPU and Graphics
Entry-level interactive TV lets viewers do more
The CX22490/22496’s powerful 32-bit RISC
than just watch programs. It upgrades the TV’s
processor and advanced video/graphics display
user navigation interface from a simple Electronic
controller provide a platform ideally suited to
Program Guide (EPG) to a more sophisticated
support Internet access and interactive multimedia
application for both digital TV programming and
applications. The CPU core easily handles computa-
enhanced information services. The services typically
tionally intensive host signal processing tasks for
offered include local news and weather, interactive
Internet applications, such as codecs for streaming
advertising and simple games.
audio, Internet telephony, speech and video.
Additionally, the CX22490/22496 provides ample CPU
An enhanced TV set top box requires more
processing power to support implementation
memory than a basic box for TV viewing. Conexant’s
of a complete, low-speed modem datapump and
interactive TV decoders feature an innovative, unified
controller in software.
memory architecture that reduces memory costs by
servicing all system requirements in a single, flexible,
Low-Cost ICs for Entry-Level Interactive TV
external 4 MB SDRAM buffer. System hardware costs
Conexant’s interactive TV decoders feature all
are further minimized by implementing analog
the major subsystems required to implement the
modem return path functionality in software running
core system and decoder electronics of a digital
on the 175 MIPS embedded ARM940T CPU. This
interactive TV set top box. This includes an MPEG-2
embedded CPU offers ample resources to power
A/V decoder (Dolby Digital audio is optional), a 32-bit
a 2,400-baud software modem datapump and
RISC CPU, a 2D graphics accelerator, a video/graphics
controller, in addition to servicing all interactive
display compositing controller and a set of peripheral
TV system requirements.
I/O ports for set top box front and back panel
you only need to add a TV encoder, tuner/demodulator,
Expandable to Advanced Interactive
Set Top Box Platform
modem codec, audio DAC, SDRAM and flash
Moving beyond the entry level, many operators are
memory ICs.
offering a “walled garden” suite of truly interactive
connectors. For a complete system hardware design,
online applications accessible through the TV. They
This high level of system-on-chip integration delivers
deliver services using both the digital broadcast
the low-cost system bill of materials sought after
stream and an analog telco modem, typically V.34
by mainstream digital, multichannel TV operators. At
or V.90. Interactive applications for this class of
the same time, our ICs offer an advanced hardware
platform include banking and shopping from home,
capability for entry-level interactive or enhanced TV.
and possibly limited Internet access and e-mail
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
decompressing the video and audio data associated with
graphics performance ideally suited for such mid-range interactive
the selected program. This generates the TV program’s
TV set top boxes, in which a system can be implemented using
picture and sound. An interactive TV decoder can also
8 MB or 16 MB of SDRAM, depending on the functionality desired.
Conexant’s powerful video/graphics display compositing engine
identify and filter information sent in the digital TV data
supports up to six independent image planes to enable the
stream. Data pertaining to interactive applications is
rich visual interface required for simultaneous TV viewing and
processed by the interactive TV decoder’s embedded CPU
application interaction. In addition, Conexant’s 2D graphics
rendering engine can composite an unlimited number of graphics
under OS control, and generates a graphical user interface
planes with transparency into a single displayable OSD plane.
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.
The interactive TV decoder’s graphics-controller function
Conexant’s architecture scales up to satisfy the requirements of
allows both the TV picture and application user interface
this computer-centric set top box model with a high-performance,
graphics to be presented as a single image on the TV, using
133 MHz, 32-bit SDRAM memory controller and a 160 MHz,
32-bit CPU providing 160 MIPS dedicated to OS and
a variety of video/graphics image scaling, filtering and
application execution.
blending techniques. The interactive TV decoder must also
provide a return channel data communications mechanism
A high-performance 2D graphics rendering engine accelerates
8/16/32bpp graphics screen updates to support multiple
to allow the application to interact with the broadcast data
overlapping graphics screen surfaces. The display-compositing
source. This is typically done via a telco or cable modem.
engine enables picture-in-graphics, flicker filtering, alpha
Finally, the interactive TV decoder should be able to
blending and other effects. The CX22490 supports direct
attachment to an IDE hard disk drive for video pause and
decrypt TV program and application content which has
Web-browser caching applications.
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.
Full-Featured Development Platform
VxWorks runtime and driver software components. The
These ICs are packaged in a fully-engineered interactive
development platform set-top box hardware has a modular
TV decoder development system that runs on third-party
design, allowing OEMs to configure the system with their
interactive middleware/RTOS platforms and provides
choice of tuner/demodulator, analog modem, TV encoder,
complete set top box functionality. The initial platform
audio DAC and SDRAM buffer size.
comes equipped with fully-integrated OpenTV, pSOS and
CX22490/22496 block diagram
Product Features
• MPEG-2 [email protected] video decoder
supporting NTSC and PAL CCIR601
image resolution
• MPEG-1/MPEG-2 audio decoder and
Dolby Digital (AC3)
• MPEG-2/DVB/ATSC/DSS transport
stream demultiplexing
• Integrated DVB common descrambler
• NDS conditional access embedded
in the CX22496
• 160 MHz 175 MIPS 32-bit
• Advanced 2D graphics rendering for
bitblt, textblt, line draw and color
expansion acceleration
• Unified memory architecture
supporting 32-bit, 133 MHz SDRAM
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strives for accuracy in all its publications, this material
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may contain errors or omissions and is subject to
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liable for any special, indirect, incidental or consequential
damages as a result of its use.
• MPEG picture and still plane upscaling
and downscaling
• Multiplane video/graphics image
compositing with color key or
256-level alpha blending
• Video-picture-in-graphics and
video-picture-in-video-picture support
• Flicker filtering, aspect ratio
conversion and hardware cursor
• 4/8/16/32-bit RGB/YCrCb graphics
• PCM audio mix and playback
– USB 1.1 OHCI host controller
(CX22490 only)
– IDE multiword DMA support
(CX22490 only)
• Serial, I2C and GPIO ports
• Bi-directional IR controller and
dual smart card controllers