ADV7189 Datasheet, PDF (37/104 Pages) Analog Devices – Multiformat SDTV Video Decoder

SDP DIGITAL NOISE REDUCTION (DNR)
Digital noise reduction is based on the assumption that high
frequency signals with low amplitude are probably noise, and
that their removal therefore improves picture quality.
DNR_EN Digital Noise Reduction Enable (SDP),
Address 0x4D, [5]
The DNR_EN bit enables the DNR block or bypasses it.
Table 80. DNR_EN Function
DNR_EN Description
0
Bypass DNR (disable).
1*
Enable digital noise reduction on the luma data.
DNR_TH[7:0] DNR Noise Threshold, Address 0x50, [7:0]
The DNR_TH[7:0] value is an unsigned 8-bit number used to
determine the maximum edge that will be interpreted as noise
and therefore blanked from the luma data. Programming a large
value into DNR_TH[7:0] causes the DNR block to interpret
even large transients as noise and remove them. The effect on
the video data will therefore be more visible.
Programming a small value causes only small transients to be
seen as noise and to be removed.
It should be noted that the recommended DNR_TH[7:0] setting
for A/V inputs is 0x04, and the recommended DNR_TH[7:0]
setting for tuner inputs is 0x0A.
Table 81. DNR_TH Function
DNR_TH[7:0] Description
0x08*
Threshold for maximum luma edges to be
interpreted as noise.
*Default value.
ADV7189
SDP COMB FILTERS
The comb filters of the ADV7189 have been greatly improved to
automatically handle video of all types, standards, and levels of
quality. Two user registers are available to customize comb filter
operation.
Depending on whichever video standard has been detected (by
autodetection) or selected (by manual programming), the
NTSC or PAL configuration registers are used. In addition to
the bits listed in this section, there are some further ADI
internal controls; please contact ADI for more information.
NTSC Comb Filter Settings
Used for NTSC-M/J CVBS inputs.
NSFSEL[1:0] Split Filter Selection NTSC (SDP),
Address 0x19, [3:2]
The NSFSEL[1:0] control selects how much of the overall signal
bandwidth is fed to the combs. A narrow split filter selection
gives better performance on diagonal lines, but leaves more dot
crawl in the final output image. The opposite is true for
selecting a wide bandwidth split filter.
Table 82.NSFSEL Function
NSFSEL[1:0]
00*
01
10
11
*Default value.
Description
Narrow
Medium
Medium
Wide
CTAPSN[1:0] Chroma Comb Taps NTSC (SDP),
Address 0x38, [7:6]
Table 83. CTAPSN Function
CTAPSN[1:0] Description
00
Do not use.
01
NTSC chroma comb adapts 3 lines (3 taps) to
2 lines (2 taps).
10*
NTSC chroma comb adapts 5 lines (5 taps) to
3 lines (3 taps).
11
NTSC chroma comb adapts 5 lines (5 taps) to
4 lines (4 taps).
*Default value.
Rev. A | Page 37 of 104