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BT.656VideoCaptureMode
Table3-2.BT.656VideoTimingReferenceCodes
DataBit1
st
Byte(FFh)2
nd
Byte(00h)3
rd
Byte(00h)4
th
Byte(XYh)
9(MSB)1001
8100F(field)
(1)
7100V(verticalblanking)
(2)
6100H(horizontalblanking)
(3)
5100P3(protectionbit3)
(4)
4100P2(protectionbit2)
(4)
3100P1(protectionbit1)
(4)
2100P0(protectionbit0)
(4)
(1)
F=0duringField1;F=1duringField2
(2)
V=0elsewhere;V=1duringfieldblanking
(3)
H=0inSAV;H=1inEAV
(4)
P0,P1,P2,andP3:DependsonF,V,andHstate.
BitsP0,P1,P2,andP3havedifferentstatesdependingonthestateofbitsF,V,andHasshownin
Table3-3.
Table3-3.BT.656ProtectionBits
LineInformationBitsProtectionBits
FVHP3P2P1P0
0000000
0011101
0101011
0110110
1000111
1011010
1101100
1110001
TheprotectionbitsallowtheporttoimplementaDEDSEC(doubleerrordetection,singleerrorcorrection)
functiononthereceivedvideotimingreferencecode.ThecorrectedvaluesfortheF,H,andVbitsbased
ontheprotectionbitvaluesareshowninTable3-4.The-entriesindicatedetecteddoublebiterrorsthat
cannotbecorrected.DetectionoftheseerrorscausestheSERRxbitinthevideoportinterruptstatus
register(VPIS)tobeset.
Table3-4.ErrorCorrectionbyProtectionBits
ReceivedF,V,andHBits
ReceivedP
3
-P
0
Bits000001010011100101110111
0000000000000-000--111
0001000--111-111111111
0010000--011-101--
0011--010-100--111
0100000--011--110-
0101-001--100--111
0110-011011011100--011
0111100--011100100100-
1000000----101110-
1001-001010----111
1010-101010-101101-101
SPRUEM1–May2007VideoCapturePort47
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