Analog Devices ADV7850 Hardware Manual page 309

ignr_clmp_vs_mar_start[4:0], Addr 44 (CP), Address 0x8A[0]; Address 0x8B[7:4]
This control is used to set the start of the window during which the clamp is ignored. It stores the unsigned number of pixel clocks
between the start position of the window relative to the leading edge of the VSync. This control should only be used if vid_std[5:0] is set
for autographics mode.
Function
ignr_clmp_vs_mar_star
t[4:0]
0x04 
ignr_clmp_vs_mar_end[4:0], Addr 44 (CP), Address 0x8A[7:3]
This control is used to set the end of the window during which the clamp is ignored. It stores the unsigned number of pixel clocks
between the end position of the window relative to the trailing edge of the VSync. This control should only be used if vid_std[5:0] is set
for autographics mode.
Function
ignr_clmp_vs_mar_end[
4:0]
0x04 
auto_sl_filter_freeze_en, Addr 44 (CP), Address 0xCB[5]
This control is used to determine if the internally generated parameter for the position of the HSync trailing edge is updated during the
VBI region. It is intended only for autographics mode. It is recommended to leave it at the default, otherwise the part may generate an
incorrect HSync trailing edge position parameter if the input synchronization is embedded and has serration pulses.
Function
auto_sl_filter_freeze_e
n
0
1 
Rev. A May 2012
Description
Default
Description
Default
Description
Do not freeze trailing edge position of HSync during VBI region
Freeze trailing edge position of HSync during VBI region
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ADV7850