Datasheet

Table Of Contents
ADV7188
Rev. A | Page 32 of 112
In automatic mode, the system preserves the maximum possible
bandwidth for good CVBS sources (because they can successfully
be combed) and 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.
The control logic is shown in
Figure 15.
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 these bits are set
to either of the automatic selection modes, the filter is selected
based on other bit selections, such as detected video standard, and
properties extracted from the incoming video itself, such as quality
and time-base stability. The automatic selection always picks the
widest possible bandwidth for the video input encountered.
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 either of the automatic selection modes, the notch filters are
only used for poor quality video signals. For all other video signals,
wideband filters are used (see
Table 36).
Table 36. YSFM Function
YSFM [4:0] Description
00000
Automatic selection, including a
wide-notch response (PAL/NTSC/SECAM)
00001 (default)
Automatic selection, including a
narrow-notch response (PAL/NTSC/SECAM)
00010 SVHS 1
00011 SVHS 2
00100 SVHS 3
00101 SVHS 4
00110 SVHS 5
00111 SVHS 6
01000 SVHS 7
01001 SVHS 8
01010 SVHS 9
01011 SVHS 10
01100 SVHS 11
01101 SVHS 12
01110 SVHS 13
01111 SVHS 14
10000 SVHS 15
10001 SVHS 16
10010 SVHS 17
10011 SVHS 18 (CCIR 601)
10100 PAL NN 1
10101 PAL NN 2
10110 PAL NN 3
10111 PAL WN 1
11000 PAL WN 2
11001 NTSC NN 1
11010 NTSC NN 2
11011 NTSC NN 3
11100 NTSC WN 1
11101 NTSC WN 2
11110 NTSC WN 3
11111 Reserved
05478-015
AUTO SELECT LUMA-
SHAPING FILTER TO
COMPLEMENT COMB
SET YSFM
YSFM IN AUTO MODE?
00000 OR 00001
VIDEO
QUALITY
BAD GOOD
SELECT WIDEBAND
FILTER AS PER
WYSFM[4:0]
AUTOMATICALLY
SELECT BEST
WIDEBAND FILTER
WYSFMOVR
1 0
USE YSFM-SELECTED
FILTER REGARDLESS OF
VIDEO QUALITY
YES NO
Figure 15. YSFM and WYSFM Control Flowchart