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Электронный компонент: CX23880/1

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10-bit video decoder
Adaptive comb filter
Global broadcast audio decoder
Stereo DACs
S input and output
DTV and broadband support
MPEG encoder and decoder interfaces
d i g i t a l i n f o t a i n m e n t p r o d u c t s
PCl Audio/Video
Broadcast Decoder
C X 2 3 8 8 0 / C X 2 3 8 8 1
D i s t i n g u i s h i n g F e a t u r e s
Single-Chip Solution Allows TV, Radio, Digital
TV and Broadband Data Capture Over the
Conexant's highly-flexible audio and video broadcast decoder
supports all analog broadcast video and audio formats in use
worldwide. This single-chip solution enables the host PC to
perform audio/video capture, video display, audio playback,
or storage and playback at a later time through software or
hardware audio/video codecs.
The CX23880/CX23881 is fully compatible with Conexant's family
of digital channel demodulators for capture of (HDTV) High
Definition Television and Standard Definition Television (SDTV)
streams, as well as broadband data over terrestrial, satellite or
cable links. The CX23880 interfaces directly to the CX23490 HDTV
hardware decoder for offloading the CPU of high-level MPEG-2
decoding tasks.
A variety of third-party peripheral connectivity options are
supported by the CX23880/CX23881. Its General Purpose Input/
Output pins and CPU host port interface enable vendor-specific
board functionality and marketplace differentiation.
Functional Overview
The CX23880/CX23881 video and broadcast audio capture chip
is a mixed-signal monolithic ic enabling a new platform for video,
audio, and data communications in the PC. The CX23880/CX23881
chips are designed to offer higher integration, functionality and
are significantly more flexible and configurable than the previous
generation FusionTM 878A.
d i g i t a l i n f o t a i n m e n t p r o d u c t s
PCl Audio/Video
Broadcast Decoder
C X 2 3 8 8 0 / C X 2 3 8 8 1
CX23880 Overview
The CX23880 is designed to offer global support
for all analog video broadcast standards in
addition to digital broadcasts via an external channel
demodulator. It is also designed to offload the CPU
of decoding tasks for High Level MPEG-2 (HDTV),
4:2:2 de-interlacing and progressive-scan DVD via
a dedicated ViP 2 Host Port interface to the CX23490
high-level MPEG-2 Decoder.
CX23881 Overview
The CX23881 is a 100% pin-compatible and software-
compatible subset of the CX23880. It is particularly
suited to the European marketplace and therefore
does not support BTSC-dBX and EIAJ audio as
broadcast in the U.S. and Japan. In addition, the ViP
host port is not supported on the CX23881 as there is
no requirement for supporting high-level MPEG-2
decoding for digital television applications. Main
Level MPEG-2 decoding for DVB broadcast applications
is supported via a dedicated MPEG port for streaming
of compressed data streams to the host for software-
based decompression.
Both the CX23880 and CX23881 support a general
purpose host port for connection to external CODECs
for compression of analog video/audio broadcasts
that can be stored on the host's hard disk or played
back in software.
Analog Video Capture Overview
The CX23880/CX23881 integrates a 10-bit NTSC/
PAL/SECAM composite and s-video decoder, image
resizer/scaler, Direct Memory Access (DMA) controller
and Peripheral Component Interface (PCI) bus
master on a single device. The CX23880/CX23881
can place video data directly into host memory for
video capture applications and into a target video
display frame buffer for video overlay applications.
Video A/Ds
Y/C separation
Decoded video data output
Video data input
Broadcast audio
Audio input
Audio output
MPEG data streaming
Bi-directional streaming
data ports
Power supply
Fusion 878A
Luma Notch and Chroma Comb
Mono line level or I
S port
S port
Adaptive multi-line 2-D comb filter
8- or 10-bit ITU-R 656 4:2:2 output
8-bit ITU-R 656/VIP 2.0 pixel input
Stereo I
S port
Stereo DACs, I
S port or PCI Bus
Dedicated 80 Mbps MPEG port
Intel/Motorola host port
and VIP 2.0 host master port
Adaptive multi-line 2-D comb filter
8- or 10-bit ITU-R 656 4:2:2 output
8-bit ITU-R 656/VIP 2.0 pixel input
Stereo I
S port
Stereo DACs, I
S port or PCI Bus
Dedicated 80 Mbps MPEG port
Intel/Motorola host port only
CX23880 block diagram
As a PCI initiator, the CX23880/CX23881 can take control
of the PCI bus to stream data as soon as the bus is available,
thereby avoiding the need for on-board frame buffers.
The CX23880/CX23881 contains a pixel data First In, First Out
(FIFO) to decouple the high-speed PCI bus from the continuous
video data stream. The video data input may be scaled, color
translated, and burst-transferred to a target location on a field
basis. This allows for simultaneous preview of one field and
capture of the other field. Alternatively, the CX23880/CX23881
is able to capture or preview both fields simultaneously.
The fields may be interlaced into memory or sent to
separate field buffers.
Video Input
Analog video signals are input to the CX23880/CX23881 via
a four-input multiplexer. The multiplexer can select between
four composite source inputs or between three composite and
a single s-video input source. When an s-video source is input
to the CX23880/CX23881, the luma component is fed through
the input analog multiplexer, and the chroma component
feeds directly into the C-input pin. An Automatic Gain Control
(AGC) circuit enables the CX23880/CX23881 to compensate
for non-standard amplitudes in the analog signal input.
d i g i t a l i n f o t a i n m e n t p r o d u c t s
Reduced Instruction Set Computing (RISC) Engine
The CX23880/CX23881 enables separate destinations for
the odd and even video fields, each controlled by a pixel
RISC instruction list. This instruction list is created by the
CX23880/CX23881 device driver and may be run in the
on-chip memory or host memory. The instructions control
the transfer of pixels to target memory locations on a byte
resolution basis. Complex clipping can be accomplished by
the instruction list, blocking the generation of PCI bus cycles
for pixels that are not to be seen on the display.
The DMA channels can be programmed on a field basis to
deliver the video data in packed or planar format. In packed
mode, YCrCb data is stored in a single continuous block of
memory. In planar mode, the YCrCb data is separated into
three streams which are burst to different target memory
blocks. Having the video data in planar format is useful for
applications where data compression is accomplished via
software and the CPU.
The CX23880/CX23881 employs a proprietary technique
known as UltraLock to lock on to the incoming analog video
signal. It consistently generates the required number of
pixels per line from an analog source in which line length
can vary by as much as a few microseconds. UltraLock's
digital locking circuitry enables the CX23880/CX23881 to
lock onto video signals quickly and accurately, regardless
of their source. The technique is completely digital, so
UltraLock can recognize unstable signals caused by
VCR head switches or any other deviation and can adapt
the locking mechanism to accommodate the source.
UltraLock uses nonlinear techniques that are difficult,
if not impossible, to implement in genlock systems.
Unlike linear techniques, it adapts the locking mechanism
Vertical Blanking Interval (VBI) Data Capture
The CX23880/CX23881 provides a flexible solution for
capturing and decoding disparate VBI data types such as
closed-caption data, teletext, vertical internal time and
control (VITC) codes, HTML data, or multicast data. The
CX23880/CX23881 can operate in a VBI line output mode,
in which the VBI data is only captured from selected lines.
This mode of operation enables concurrent capture of VBI
lines containing ancillary data and normal video image
data. In addition, the CX23880/CX23881 supports a VBI
frame output mode in which every line in the video frame
is treated as if it were a VBI line. This mode of operation is
designed for use with still-frame capture and processing
applications, where sophisticated image decoding can be
performed in the software domain.
With the advent of more powerful CPUs that enable
software-based video compression, low-cost hardware
MPEG encoders, cheap and rewritable storage media, and
pervasive broadband communications, original content
protection is paramount. To this end, the CX23880/CX23881
fully implements Macrovision 7.01 detection. When an end-
user attempts to connect a digital video disk (DVD) player,
a digital satellite/cable decoder's composite, or s-video out-
puts to the input of a CX23880/ CX23881-based PCI card,
Macrovision pulses and signals are detected, and appropriate
flag bits are set. It is up to the board vendor to read the flag
bits and determine what action will be taken.
Analog Audio Capture
The CX23880/CX23881 captures and decodes all major
terrestrial broadcast audio standards. The CX23880/CX23881
digitizes and oversamples the low intermediate frequency
(IF) signal from a TV tuner, and extracts and decodes the
broadcast audio signal. The decoded audio is sample rate
converted to a 48 KHz pulse code modulation (PCM) stereo
signal to simplify processing and interfacing. This 48 KHz
stream can be routed to the built-in (90 dB Signal-to-Noise
Ratio (SNR) stereo audio Digital-to-Analog Converters
(DACs) for connection to the PC's sound card or headphones,
to an external Digital-Audio Interface, or to the PCI bus and
host for direct capture by a software audio codec. The
CX23881 only supports NICAM, A2 and FM broadcast audio
standards primarily for the European marketplace.
If capture of line-level stereo audio signals is required, an
inexpensive audio analog-to-digital converter A/D may
be directly connected to the CX23880/CX23881's I2S input
port and controlled via the serial bus master.
ITU-R 656 4:2:2 Data Output
The CX23880/CX23881 provides a 27 MHz, 8- or 10-bit
ITU-R 656 decoded video output interface to allow
connection of a third-party MPEG-2 encoder or other type
of video codec. This is useful when the host CPU is not
powerful enough to perform such tasks in software, or
when high-quality encoding must be achieved. Please
contact Conexant Application Engineering for a list of
supported third-party video compressors.
TV/FM application example
Single-chip capture/record of broadcast TV and radio to PC
Global video standards support
Global audio standards support including FM/AM radio
Many I/O ports to differentiate design
ITU-R 656/VIP 2.0 Pixel Data Input
The CX23880/CX23881 provides a 27 MHz, 8-bit ITU-R 656
decoded video input interface to allow a third-party MPEG-2
decoder or codec to send 4:2:2 data over the PCI bus to
a target video display frame buffer for video overlay.
Alternatively, 480-line progressive scan video from the
CX23490 all-format MPEG-2 decoder may be input to this
port using Video Interface Port (VIP) 2.0-compliant pixel
timing at up to 54 MHz.
Audio Out
Serial Bus
erial Data
2nd IF
Composite or
S-Video In
What is a Broadcast Decoder?
A broadcast decoder is designed to capture and decode the
video and audio portions of any analog TV broadcast
signal. In addition, a broadcast decoder must be able to
address the transition to all-digital broadcasting by offering
a variety of methods to connect to digital TV channel
demodulators. Sufficient I/O must be provided to support
external hardware-based compression of analog video/audio
signals in order to enable storage onto hard disks or CDROM.
Conexant's broadcast decoder meets these objectives
in the following way:
1) It captures and decodes all variations of NTSC, PAL
and SECAM video standards into digital RGB or YUV
pixel streams.
2) It captures and decodes all broadcast audio standards
used worldwide such as BTSC/DBX, NICAM, A2, EIAJ
and FM/AM, into 48 KHz PCM streams or stereo left
and right audio signals.
3) It facilitates "analog to MPEG" conversion by providing
an 8- or 10-bit ITU-R 656 pixel interface to an external
MPEG 2 encoder for real-time compression. Providing
a streaming host port or MPEG port for DMA of
compressed data to the host or hard disk.
4) It provides a dedicated high-speed streaming MPEG
port that is compatible with ATSC, DVB and ISDB digital
television channel demodulators for DMA to the host
or hard disk.
TV/FM block diagram