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3.6.1HorizontalAncillary(HANC)DataCapture
3.6.2VerticalAncillary(VANC)DataCapture
3.7RawDataCaptureMode
3.7.1RawDataCaptureNotification
RawDataCaptureMode
NospecialprovisionsaremadeforthecaptureofHANCdata.HANCdatamaybecapturedusingthe
normalvideocapturemechanismbyprogrammingVCXSTRTtooccurbeforetheSAV(whenHCOUNTis
resetbytheEAVcode)orbyprogrammingVCXSTOPtooccurpasttheEAVcode(whenHCOUNTis
resetbytheSAVcode).NotethattheEAVcodeandanysubsequentHANCdatawillstillbeYCbCr
separated.SoftwaremustparsetheY,Cb,andCrmemorybufferstodetermineanyHANCdatapresence
andtoreconstructtheHANCdata.TheVCTHRLDvalueandEDMAsizemustbeprogrammedto
comprehendtheadditionalsamples.Youmustdisablescalingandchromare-samplingwhenincludingthe
captureofHANCdatatopreventdatacorruption.
VANC(orVBI)dataiscommonlyusedforsuchfeaturesasteletextandclosed-captioning.Nospecial
provisionsaremadeforthecaptureofVBIdata.VBIdatamaybecapturedusingthenormalcapture
mechanismbyprogrammingVCYSTARTtooccurbeforethefirstlineofactivevideoonthefirstlineof
desiredVBIdata.(VCOUNTmustberesetbyanEAVwithV=1).NotethattheVBIdatawillbeYCbCr
separated.SoftwaremustparsetheY,Cb,andCrmemorybufferstodetermineanyVBIdatapresence
andtoreconstructtheVBIdata.Youmustdisablescalingandchromare-samplingwhenthecaptureof
VBIdataisdesiredorthedatawillbecorruptedbythefilters.
Intherawdatacapturemode,thedataissampledbytheinterfaceonlywhentheCAPENsignalisactive.
Dataiscapturedattherateofthesender'sclock,withoutanyinterpretationorstart/stopofcapturebased
onthedatavalues.
Toensureinitialcapturesynchronizationtothebeginningofaframe,anoptionalsetupsynchronization
enable(SSE)bitisprovidedinVCxSTRT1.IftheSSEbitisset,thenwhentheVCENbitissetto1,the
videoportwillnotstartcapturingdatauntilafterdetectingtwoverticalblankingintervals.IftheSSEbitis
clearedto0,capturebeginsimmediatelywhentheVCENbitisset.
TheincomingdigitalvideocapturedataisstoredintheFIFO,whichis2560-bytes(indual-channel
operation)or5120-bytesdeep(insingle-channeloperation).Thememory-mappedlocationYSRCxis
associatedwiththeYbuffer.TheYSRCxlocationisaread-onlyregisterandisusedtoaccessvideodata
samplesstoredinthebuffer.
Thecaptureddatasetsize(imagesize)issetbyVCxSTOPn.TheVCXSTOPandVCYSTOPbitssetthe
24-bitsofdatasetsize(VCXSTOPsetsthelower12bitsandVCYSTOPsetstheupper12bits).Capture
iscompleteandtheappropriateF1C,F2C,orFRMCbitissetwhenthecaptureddatasizereachesthe
combinedVCYSTOPandVCXSTOPvalue.TheCAPENsignalmustgoinactiveforaminimumoftwo
VPCLKcyclesafterthepixelcounthasexpired.KeepingtheCAPENsignalactiveafterthepixelcount
expiresmaycausealossofpixels;therefore,itisnotrecommendedtopermanentlyenabletheCAPEN
signalduringrawdatacapturemode.
ThevideoportgeneratesaYEVTafterthespecifiednumberofnewsampleshasbeencapturedinthe
buffer.ThenumberofsamplesrequiredtogenerateYEVTxisprogrammableandissetintheVCTHRLDn
bitsofVCxTHRLD.OneveryYEVT,theEDMAshouldmovedatafromthebuffertotheDSPmemory.
WhenmovingdatafromthebuffertotheDSPmemory,theEDMAshouldusetheYSRCxlocationasa
sourceaddress.
RawdatamodecapturesasingledatapacketofinformationusingonlyCAPENforcontrol.Field
informationisavailableonlyforchannelAoperationusingtheFIDinputonVCTL3.IftheRDFEbitin
VCACTLisset,thenthevideoportsamplestheFIDinputatthestartofeachdatablock(whenDCOUNT
=0andCAPENAisactive)todeterminethecurrentfield.Inthiscase,theCON,FRAME,CF1,andCF2
bitsinVCxCTLareusedinamanneridenticaltoBT.656mode(seeSection3.4.1).
SPRUEM1–May2007VideoCapturePort61
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