2.0 Internal Registers
CX25870/871
2.4 Reading Registers
Flicker-Free Video Encoder with Ultrascale Technology
Table 2-5. Programming Detail For All Read/Write Registers (16 of 16)
Bit/Register
Names
Bit Location
Bit/Register Definition
Y_ALTFF[1:0]
Bits [1:0]–34
Luma alternate flicker filter selection. This bit will only have an effect when ADPT_FF is
set. Y_ALTFF should always be programmed to a value greater than or equal to F_SELY.
00 = 5 line (DEFAULT)
01 = 2 line
10 = 3 line
11 = 4 line
Y_OFF[7:0]
Bits [7:0]–5A
Brightness control. This is the luminance level offset. Expressed as a 2’s complement
number. (DEFAULT = 0x00)
The luminance level offset is referenced from black, and can be adjusted from -22.31
IRE (below black) to +22.14 IRE (above black). Active video will be added to the offset
level. Y_OFF is a two’s complement number, such that 0x00 = 0 IRE offset 0x7 is +22.14
IRE offset and 0x8 is -22.31 IRE offset. 1 lsb =1.25 mV or .175 IRE of adjustment.
Y_THRESH[2:0]
Bits [2:0]–36
Bits {2:0]–CA
Controls the sensitivity or limit of turning on the alternate flicker filter for luma in
adaptive flicker filter mode. (DEFAULT = 000)
YATTENUATE[2:0]
Works in conjunction with register MY for contrast control. This bit field is for Luma
Attenuation in discrete steps.
000 = 1.0 gain (no attenuation) (DEFAULT)
001 = 15/16 gain
010 = 7/8 gain
011 = 3/4 gain
100 = 1/2 gain
101 = 1/4 gain
110 = 1/8 gain
111 = 0 gain (Force Luma to 0)
YCORING[2:0]
Bits [5:3]–CA
Luma Coring. Values below the YCORING[2:0] limits that follow are automatically
clamped to pure black by the encoder.
000 = Bypass (DEFAULT)
001 = 1/128 of range
010 = 1/64 of range
011 = 1/32 of range
100 = 1/16 of range
101 = 1/8 of range
110 = 1/4 of range
111 = Reserved
YLPF[1:0]
YSELECT
Bits [5:4]–96
Bit 6–36
Luma Post-Flicker Filter/Scaler Horizontal Low Pass Filter:
00 = Bypass (DEFAULT)
01 = Luma Horizontal LPF1 setting
10 = Luma Horizontal LPF2 setting
11 = Luma Horizontal LPF3 setting
This bit will only have an effect when ADPT_FF is set.
0 = Use the C_THRESH value to determine the threshold for turning on the alternate
flicker filter setting for chrominance. (DEFAULT)
1 = Use the Y_THRESH value to determine the threshold for turning on the alternate
flicker filter setting for chrominance. Both chroma and luma digital data is automatically
processed with their alternate flicker filter settings when the Y_THRESH limit is
exceeded.
2-24
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
