BT848 ETC, BT848 Datasheet - Page 131

• Manufacturer Part Number: BT848
• Description: Single-Chip Video Capture for PCI
• Manufacturer: ETC

Bt848/848A/849A
Single-Chip Video Capture for PCI
Luma Gain Register, Lower Byte
Memory Mapped Location 0x030 – (CONTRAST_LO)
This is the alternate definition for the CONTRAST_LO register when using the Bt848A/849A.
video mode).
justments as in analog video decode operation.
Brooktree
Bits
Upon reset it is initialized to 0xD8 (this must be changed to 0x80 to get standard contrast values when in digital
The CONTRAST register when used in digital video input mode, requires different programming time contrast ad-
[7:0]
Type
®
RW
CONTRAST_LO
Default
0xD8
Name
CONTRAST_LO
The least significant byte of the luma gain (contrast) value.
NOTE:
Decimal Value
511
510
.
.
217
216
.
.
128
.
.
1
0
The BRIGHT function has the same register definition in the digital sec-
tion as in the analog section. However, the Bright function does precede
the CONTRAST function in the decoder signal processing sequence,
therefore any brightness applied is also gained by the CONTRAST set-
ting.
C
L848A_A
ONTROL
Description
The CON_L_MSB bit and the CONTRAST_LO register concate-
nate to form the 9-bit CONTRAST register. The value in this regis-
ter is multiplied by the luminance value to provide contrast
adjustment.
Hex Value
0x1FF
0x1FE
.
.
0x0D9
0x0D8
.
.
0x080
.
.
0x001
0x000
R
EGISTER
D
IGITAL
V
IDEO
I
N
% of Original Signal
399.22%
398.43%
.
.
169.53%
168.75%
.
.
100%
.
.
0.78%
0.00%
S
Luma Gain Register, Lower Byte
UPPORT
(B
T
848A/849A O
121
NLY
)