ADV7180
Data Sheet
An automatic mode is provided that allows the ADV7180 to
evaluate the quality of the incoming video signal and select the
filter responses in accordance with the signal quality and video
standard. YFSM, WYSFMOVR, and WYSFM allow the user to
manually override the automatic decisions in part or in full.
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 selection is based on other register
selections, such as detected video standard, as well as properties
extracted from the incoming video itself, such as quality and
time base stability. The automatic selection always selects the
widest possible bandwidth for the video input encountered.
The luma shaping filter has three control registers.
•
YSFM[4:0] allows the user to manually select a shaping
filter mode (applied to all video signals) or to enable an
automatic selection (depending on video quality and video
standard).
The Y-shaping filter mode operates as follows:
•
•
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,
wideband filters are used.
•
•
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 composite (CVBS), component
(YPrPb), and SVHS (Y/C) input signals.
In automatic mode, the system preserves the maximum possible
bandwidth for good CVBS sources (because they can be successfully
combed) as well as for luma components of YPrPb and Y/C
sources (because 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 to
reduce visual artifacts.
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 on
luma shaping filters, see the Y Shaping Filter section and the
flowchart shown in Figure 21.
When WYSFMOVR is 0, the shaping filter for good quality
video signals is selected automatically.
The decisions of the control logic are shown in Figure 21.
Setting WYSFMOVR to 1 (default) enables manual override via
WYSFM[4:0].
SET YSFM
YSFM IN AUTO MODE?
00000 OR 00001
YES
NO
VIDEO
QUALITY
BAD
GOOD
USE YSFM SELECTED
FILTER REGARDLESS OF
VIDEO QUALITY
AUTO SELECT LUMA
SHAPING FILTER TO
COMPLEMENT COMB
WYSFMOVR
1
0
SELECT WIDEBAND
FILTER AS PER
WYSFM[4:0]
SELECT AUTOMATIC
WIDEBAND FILTER
Figure 21. YSFM and WYSFM Control Flowchart
Rev. G | Page 32 of 120
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