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3.4.3HorizontalSynchronization
VDIN[9−2]
80.0
80.0
10.0
FF.C
00.0
00.0
Cb 0
Y 2
Cb 359
Cr 359
Y 719
Y 0
Cr 0
Y 1
Cb 1
One Line
XY.0
10.0
80.0
10.0
FF.C
00.0
00.0
XY.0
80.0
80.0
10.0
FF.C
00.0
00.0
XY.0
10.0
855 856 857 0 1 2
718 719 720 721 722 723
720 721 722 723
HCOUNT
SAVEAV Blanking Data EAV
Active VideoBlanking
VCLKIN
Next Line
4
4
268 1440
EXC=0
HRST=0
One Line
133 134 135 136 273 274
854 855 856 857 0 1
856 857 0 1
HCOUNT
Next Line
EXC=0
HRST=1
n n+1n−1
VCOUNT
Y 718
BT.656andY/CModeFieldandFrameOperation
Horizontalsynchronizationdetermineswhenthehorizontalpixel/samplecounterisreset.TheEXCand
HRSTbitsinVCxCTLallowyoutoprogramtheeventthattriggersthestartofaline.Theencodingof
thesebitsisshowninTable3-8.
Table3-8.HorizontalSynchronizationProgramming
VCxCTLBit
HModeEXCHRSTHorizontalCounterResetPoint
000EAVcode(H=1)-beginningofhorizontalblanking.
101SAVcode(H=0)-Startofactivevideo.
210VCTL1inputactiveedge-beginningofhorizontalblankingorhorizontalsync
period.(VCTL1mustbeconfiguredasahorizontalcontrolsignal.)
311VCTL1inputinactiveedge-firstactivepixelonlineorendofhorizontalsync.
(VCTL1mustbeconfiguredasahorizontalcontrolsignal.)
HMode0isusedforBT.656orY/Ccapture(withembeddedcontrol)andcorrespondstotheideathat
eachlinebeginswiththehorizontalblankingperiod.Itdoesnotalignwithmoststandardsthatstart
countingwiththefirstactivepixel;therefore,isonlyusefulifcapturingofHANCdatabeforetheSAVcode
isdesired.HMode1isthedefaultmodeandcorrespondstomostdigitalvideostandardsbymakingthe
firstactivepixelpixel0.Ithastheeffectofassociatinghorizontalblankingperiodswiththeendofthe
previouslineratherthanthebeginningoftheline,butthisisonlyanissueifyoutrytocaptureHANCdata.
Ineithermode,HCOUNTincrementsoneveryVCLKINedgeforY/Coperationandoneveryother
VCLKINedgeforBT.656operationbutonlywhenCAPENisactive.HCOUNToperationforHMode1and
HMode2isshowninFigure3-5.
HMode2andHMode3areusedforBT.656orY/CcapturewithoutembeddedEAV/SAVcodeandallow
alignmentwitheitherthebeginningofthehorizontalblankingperiodorthefirstactivepixel,orthe
beginningorendofhorizontalsyncdependingontheVCTL1input.WhenVCTL1isconfiguredasa
horizontalcontrolinput,noexternalCAPENsignalisavailablesotheCAPENsignalisconsideredto
alwaysbeactive.HCOUNToperationforHMode3andHMode4isshowninFigure3-6forVCTL
operatingaseitherHSYNCorAVID.
Figure3-5.HCOUNTOperationExample(EXC=0)
SPRUEM1–May2007VideoCapturePort55
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