ADV7189B_15 Datasheet, PDF (32/104 Pages) Analog Devices – Multiformat SDTV Video Decoder

ADV7189B
For example, program the ADV7189B into manual fixed gain
mode with a desired gain of 0.89:
1. Use Equation 1 to convert the gain:
0.89 × 2048 = 1822.72
2. Truncate to integer value:
1822.72 = 1822
3. Convert to hexadecimal:
1822d = 0x71E
4. Split into two registers and program:
Luma Gain Control 1[3:0] = 0x7
Luma Gain Control 2[7:0] = 0x1E
5. Enable Manual Fixed Gain Mode:
Set LAGC[2:0] to 000
BETACAM Enable Betacam Levels, Address 0x01[5]
If YPrPb data is routed through the ADV7189B, the automatic
gain control modes can target different video input levels, as
outlined in. Note the BETACAM bit is valid only if the input
mode is YPrPb (component). The BETACAM bit sets the target
value for AGC operation. A review of the following sections is
useful.
• 190HINSEL[3:0] Input Selection, Address 0x00[3:0] to find out
how component video (YPrPb) can be routed through the
ADV7189B.
• Video 19H Standard Selection to select the various standards,
for example, with and without pedestal.
The automatic gain control (AGC) algorithms adjust the levels
based on the setting of the BETACAM bit. See Table 192H 37.
Table 37. BETACAM Function
BETACAM Description
0 (default) Assuming YPrPb is selected as input format.
Selecting PAL with pedestal selects MII.
Selecting PAL without pedestal selects SMPTE.
Selecting NTSC with pedestal selects MII.
Selecting NTSC without pedestal selects SMPTE.
1
Assuming YPrPb is selected as input format.
Selecting PAL with pedestal selects BETACAM.
Selecting PAL without pedestal selects BETACAM
variant.
Selecting NTSC with pedestal selects BETACAM.
Selecting NTSC without pedestal selects
BETACAM variant.
Table 38. Betacam Levels
Betacam
Name (mV)
Betacam
Variant
(mV)
Y
0 to 714
Range (incl. 7.5%
pedestal)
0 to 714
U and –467 to +467
V
Range
–505 to
+505
Sync 286
286
Depth
SMPTE
(mV)
0 to
700
–350
to
+350
300
MII (mV)
0 to 700 (incl.
7.5%
pedestal)
–324 to +324
300
PW_UPD Peak White Update, Address 0x2B[0]
The peak white and average video algorithms determine the
gain based on measurements taken from the active video. The
PW_UPD bit determines the rate of gain change. LAGC[2:0]
must be set to the appropriate mode to enable the peak white or
average video mode in the first place. For more information, refer
to the 193HLAGC[2:0] Luma Automatic Gain Control, Address
0x2C[7:0] section.
Setting PW_UPD to 0 updates the gain once per video line.
Setting PW_UPD to 1 (default) updates the gain once per field.
Chroma Gain
CAGC[1:0] Chroma Automatic Gain Control,
Address 0x2C[1:0]
The two bits of color automatic gain control mode select
the basic mode of operation for automatic gain control in the
chroma path.
Table 39. CAGC Function
CAGC[1:0] Description
00
Manual fixed gain (use CMG[11:0]).
01
Use luma gain for chroma.
10 (default) Automatic gain (based on color burst).
11
Freeze chroma gain.
CAGT[1:0] Chroma Automatic Gain Timing,
Address 0x2D[7:6]
The chroma automatic gain timing register allows the user
to influence the tracking speed of the chroma automatic gain
control. This register has an effect only if the CAGC[1:0]
register is set to 10 (automatic gain).
Table 40. CAGT Function
CAGT[1:0]
Description
00
Slow (TC = 2 sec)
01
Medium (TC = 1 sec)
10
Fast (TC = 0.2 sec)
11 (default)
Adaptive
Rev. B | Page 32 of 104