adv7189b Analog Devices, Inc., adv7189b Datasheet - Page 27
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adv7189b
Manufacturer Part Number
adv7189b
Description
Multiformat Sdtv Video Decoder
Manufacturer
Analog Devices, Inc.
Datasheet
1.ADV7189B.pdf
(104 pages)
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An automatic mode for Y-shaped filtering is provided. In this
mode, the ADV7189B evaluates the quality of the incoming
video signal and selects the filter responses in accordance with
the signal quality and video standard. YFSM, WYSFMOVR,
and WYSFM allow the user to manually override these
automatic decisions in part or in full.
The luma shaping filter has three control registers:
x
x
x
In automatic mode, the system preserves the maximum possible
bandwidth for good CVBS sources (since they can successfully
be combed) as well as for luma components of YPrPb and YC
sources, since they need not be combed. For poor quality signals,
the system selects from a set of proprietary shaping filter
responses that complements comb filter operation in order to
reduce visual artifacts. The decisions of the control logic are
shown in
YSFM[4:0] allows the user to manually select a shaping
filter mode (applied to all video signals) or to enable an
automatic selection (dependent on video quality and
video standard).
WYSFMOVR allows the user to manually override the
WYSFM decision.
WYSFM[4:0] allows the user to select a different shaping
filter mode for good quality CVBS, component (YPrPb),
and S-VHS (YC) input signals.
F igure 11.
1 7 5 H
COMPLEMENT COMB
AUTO SELECT LUMA
SHAPING FILTER TO
BAD
SELECT WIDEBAND
FILTER AS PER
WYSFM[4:0]
QUALITY
VIDEO
Figure 11. YSFM and WYSFM Control Flowchart
1
YES
Rev. B | Page 27 of 104
WYSFMOVR
GOOD
YSFM IN AUTO MODE?
00000 OR 00001
SET YSFM
SELECT AUTOMATIC
WIDEBAND FILTER
YSFM[4:0] Y-Shaping Filter Mode, Address 0x17[4:0]
The Y-shaping filter mode bits allow the user to select from
a wide range of low-pass and notch filters. When switched in
automatic mode, the filter is selected based on other register
selections, for example, detected video standard, as well as
properties extracted from the incoming video itself, for example,
quality, time base stability. The automatic selection always picks
the widest possible bandwidth for the video input encountered.
x
x
WYSFMOVR Wideband Y-Shaping Filter Override,
Address 0x18[7]
Setting the WYSFMOVR bit enables the use of the WYSFM[4:0]
settings for good quality video signals. For more information,
refer to the general discussion of the luma-shaping filters in the
Y-Shaping Filter section and the flowchart shown in
When WYSFMOVR is 0, the shaping filter for good quality
video signals is selected automatically.
Setting WYSFMOVR to 1 (default) enables manual override via
WYSFM[4:0].
If the YSFM settings specify a filter (that is, YSFM is set
to values other than 00000 or 00001), the chosen filter is
applied to all video, regardless of its quality.
In automatic selection mode, the notch filters are only used
for bad quality video signals. For all other video signals, wide
band filters are used.
0
FILTER REGARDLESS FOR
GOOD AND BAD VIDEO
USE YSFM SELECTED
NO
ADV7189B
F igure 11.
1 7 6 H