THC7984_15 Datasheet, PDF (25/46 Pages) THine Electronics, Inc. – 10-bit 3-channel Video Signal Digitizer

THC7984_Rev.2.0_E
R16[0] Clamp COAST Source
It's sometimes necessary to make the clamp suspend while the period which is including the signals that disturb the
clamp such as a copy protection signal. The clamp COAST signal is the signal which makes the clamp stop.
0: Internal Clamp COAST
1: External Clamp COAST
R17[6] Clamp Pulse Start Reference Edge
The timing of Clamp pulse is set based on the edge of the HSYNC input. Selecting the edge of the HSYNC input
0: the leading edge of the HSYNC input is referred.
1: the trailing edge of the HSYNC input is referred.
* In case of 3-level sync, the leading edge or trailing edge of the positive pulse is referred.
R17[5:4] R-ch (Pr-ch) Clamp Mode
R17[3:2] G-ch (Y-ch) Clamp Mode
R17[1:0] B-ch (Pb-ch) Clamp Mode
As a clamp method, pedestal clamp, midscale clamp, and 256-level clamp can be selected.
00b: Pedestal clamp for RGB and Y (luminance) clamps black level to 0 with automatic offset cancel (if clamp level off-
set is set to 0) . The Automatic offset cancel circuitry eliminates any offset errors.
01b: Midscale clamp for PbPr clamps to 512 with automatic offset cancel (if clamp level offset is set to 0) . The
Automatic offset cancel circuitry eliminates any offset errors.
10b: Reserved
11b: 256-level clamp clamps to 256 with automatic offset cancel (if clamp level offset is set to 0). The Automatic offset
cancel circuitry eliminates any offset errors.
* It's possible to set a clamp pulse on sync part and realize sync tip clamp by a pedestal clamp (R17 [5:4], R17 [3:2] and
R17 [1:0] =00b) .
R18[7:0] Clamp Pulse Start Position
Set the clamp pulse start position in steps of 1 pixel with reference to clamp pulse start reference edge (selected by
R17[6]) .
R19[7:0] Clamp Pulse Width
Set the clamp pulse width in steps of 1 pixel.
* When the register is set to 0, clamp pulse is not generated.
* Set the end position of clamp pulse (R18[7:0] + R19[7:0]) more than 16 pixels front of active video period because
Clamp Offset Cancel is completed after 16 pixels from the clamp pulse.
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