ADV7181 AD [Analog Devices], ADV7181 Datasheet - Page 19

• Manufacturer Part Number: ADV7181
• Description: Multiformat SDTV Video Decoder
• Manufacturer: AD [Analog Devices]

STANDARD DEFINITION PROCESSOR (SDP)
A block diagram of the ADV7181B’s standard definition
processor (SDP) is shown in Figure 7.
The ADV7181B can handle standard definition video in CVBS,
YC, and YPrPb formats. It can be divided into a luminance and
chrominance path. If the input video is of a composite type
(CVBS), both processing paths are fed with the CVBS input.
SD LUMA PATH
The input signal is processed by the following blocks:
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•
•
•
•
•
Digital Fine Clamp. This block uses a high precision
algorithm to clamp the video signal.
Luma Filter Block. This block contains a luma decimation
filter (YAA) with a fixed response, and some shaping filters
(YSH) that have selectable responses.
Luma Gain Control. The automatic gain control (AGC) can
operate on a variety of different modes, including gain
based on the depth of the horizontal sync pulse, peak white
mode, and fixed manual gain.
Luma Resample. To correct for line-length errors as well as
dynamic line-length changes, the data is digitally
resampled.
Luma 2D Comb. The two-dimensional comb filter provides
YC separation.
AV Code Insertion. At this point, the decoded luma (Y)
signal is merged with the retrieved chroma values. AV
codes (as per ITU-R. BT-656) can be inserted.
DIGITIZED C (YC)
DIGITIZED Y (YC)
DIGITIZED CVBS
DIGITIZED CVBS
CHROMA
STANDARD DEFINITION PROCESSOR
DIGITAL
DIGITAL
MACROVISION
CLAMP
CLAMP
LUMA
FINE
FINE
DETECTION
RECOVERY
CHROMA
DEMOD
F
SC
Figure 7. Block Diagram of the Standard Definition Processor
RECOVERY
VBI DATA
EXTRACT
CHROMA
FILTER
FILTER
LUMA
SYNC
AUTODETECTION
STANDARD
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PREDICTOR
CONTROL
CONTROL
LENGTH
GAIN
GAIN
LINE
SD CHROMA PATH
The input signal is processed by the following blocks:
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•
•
•
•
•
•
RESAMPLE
RESAMPLE
RESAMPLE
CONTROL
CHROMA
LUMA
Digital Fine Clamp. This block uses a high precision
algorithm to clamp the video signal.
Chroma Demodulation. This block employs a color
subcarrier (Fsc) recovery unit to regenerate the color
subcarrier for any modulated chroma scheme. The
demodulation block then performs an AM demodulation
for PAL and NTSC, and an FM demodulation for SECAM.
Chroma Filter Block. This block contains a chroma
decimation filter (CAA) with a fixed response, and some
shaping filters (CSH) that have selectable responses.
Gain Control. Automatic gain control (AGC) can operate
on several different modes, including gain based on the
color subcarrier’s amplitude, gain based on the depth of the
horizontal sync pulse on the luma channel, or fixed manual
gain.
Chroma Resample. The chroma data is digitally resampled
to keep it perfectly aligned with the luma data. The
resampling is done to correct for static and dynamic line-
length errors of the incoming video signal.
Chroma 2D Comb. The two-dimensional, 5-line,
superadaptive comb filter provides high quality YC
separation in case the input signal is CVBS.
AV Code Insertion. At this point, the demodulated chroma
(Cr and Cb) signal is merged with the retrieved luma
values. AV codes (as per ITU-R. BT-656) can be inserted.
CONTROL
2D COMB
CHROMA
2D COMB
LUMA
SLLC
INSERTION
CODE
AV
VIDEO DATA
OUTPUT
MEASUREMENT
BLOCK (= >1
VIDEO DATA
PROCESSING
BLOCK
ADV7181B
2
C)