ADV7180
BETACAM, Enable Betacam Levels, Address 0x01 [5]
PW_UPD, Peak White Update, Address 0x2B [0]
If YPrPb data is routed through the ADV7180, the automatic
gain control modes can target different video input levels, as
outlined in Table 40. Note that the BETACAM bit is valid only if
the input mode is YPrPb (component). The BETACAM bit sets
the target value for AGC operation.
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 LAGC[2:0], Luma Automatic Gain Control,
Address 0x2C [6:4] section.
A review of the following sections is useful:
•
MAN_MUX_EN, Manual Input Muxing Enable,
Address 0xC4 [7] for how component video (YPrPb)
can be routed through the ADV7180.
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
•
Video Standard Selection to select the various standards,
for example, with and without pedestal.
CAGC[1:0], Chroma Automatic Gain Control,
Address 0x2C [1:0]
The automatic gain control (AGC) algorithms adjust the levels
based on the setting of the BETACAM bit (see Table 38).
The two bits of color automatic gain control mode select the
basic mode of operation for automatic gain control in the
chroma path.
Table 38. 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
Assuming YPrPb is selected as input format
Selecting PAL with pedestal selects BETACAM
1
Selecting PAL without pedestal selects BETACAM variant
Selecting NTSC with pedestal selects BETACAM
Selecting NTSC without pedestal selects BETACAM variant
Table 39. CAGC Function
CAGC[1:0]
Description
00
01
Manual fixed gain (use CMG[11:0])
Use luma gain for chroma
10 (default)
11
Automatic gain (based on color burst)
Freeze chroma gain
Table 40. Betacam Levels
Name
Betacam (mV)
Betacam Variant (mV)
0 to 714
SMPTE (mV)
0 to 700
MII (mV)
Y
0 to 714 (incl. 7.5% pedestal)
0 to 700 (incl. 7.5% pedestal)
Pb and Pr
Sync Depth
–467 to +467
286
–505 to +505
286
–350 to +350
300
–324 to +324
300
Rev. A | Page 34 of 112
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