Comb; Comb Activation; Figure 18: 3D Comb And Motion Detection Operation - Analog Devices ADV7850 Hardware Manual

Function
sdp_ck_high_thr[7:0]
00011010 
6.7 3D COMB
The ADV7850 has the ability to separate the luminance (Y) and chrominance (C) components using 1D (horizontal), 2D (horizontal and
vertical), or 3D (temporal) processing.
Current
(input)
CVBS
frame
Off-chip
Frame
Memory
Delayed
frame s
When the picture content is static, the 3D comb filter in the ADV7850 combines video frames to give perfect Y/C separation results.
Artifacts of 1D and 2D methods such as dot crawl, cross color, and hanging dots are eliminated. The sharpness and stillness of the
decoded picture are improved using the 3D comb.
Once the picture content begins to move, 3D Y/C separation is no longer possible and 2D or 1D combing must be used instead. The
ADV7850 features advanced motion detection, enabling motion adaptive combing between 3D and 2D or 1D Y/C separation methods.
This maximizes the benefit from 3D processing while minimizing temporal artifacts on moving picture regions.
Note: 3D combing requires video frame storage in external memory. Where external memory is not connected, sdp_3d_comb_en must be
disabled.
3D Comb Activation
6.7.1
sdp_3d_comb_en, Addr 90 (SDP), Address 0x12[0]
This control is used to disable the 3D comb filter. When the 3D comb is enabled, automatic 2D/3D comb switching is applied based on
the detected video type. When the 3D comb is disabled, 2D combing only is applied.
Rev. A May 2012
Description
Color kill high threshold
Video lines from
current frame
On-chip
Line
Video lines from first
Memories
delayed frame

Figure 18: 3D Comb and Motion Detection Operation

2D Comb
Filter
3D Comb
Filter
Motion
Detection
87
ADV7850
Y
2D Y Y out
Mixer
3D Y
C
2D C C o ut
Mixer
3D C
Per -pixel Y & C
mot ion est imates