Axis P1365-E - Page 23

AXISP1365-ENetworkCamera
VideoandAudio
•Compression.Thecompressionlevelaffectstheimagequality,bandwidthandlesizeofsavedimages;thelowerthe
compression,thehighertheimagequalitywithhigherbandwidthrequirementsandlargerlesizes.
•Mirrorimage.Ifrequired,theimagecanbemirrored.
•Rotateimage.Ifrequired,theimagecanberotated.
•Maximumframerate.Toavoidbandwidthproblems,theframerateallowedtoeachviewercanbeLimitedtoaxed
amount.Alternatively,theframeratecanbesetasUnlimited,whichmeanstheAxisproductalwaysdeliversthehighest
frameratepossibleunderthecurrentconditions.
•Overlaysettings.SeeOverlayonpage28.
ClickSavetoapplythenewsettings.
H.264
H.264,alsoknownasMPEG-4Part10/AVC,isavideocompressionstandardthatprovideshighqualityvideostreamsatlowbitrates.
AnH.264videostreamconsistsofdifferenttypesofframessuchasI-framesandP-frames.AnI-frameisacompleteimagewhereas
P-framesonlycontainthedifferencesfrompreviousframes.
TheH.264streamsettingscanbeconguredfromtheVideo&Audio>VideoStreampage.SelecttheH.264tab.Thesettings
denedinthispagewillapplytoallH.264streamsthatdonotuseastreamprole.
TheGOVlengthisthenumberofframesbetweentwoconsecutiveI-frames.IncreasingtheGOVlengthmaysaveconsiderablyon
bandwidthrequirementsinsomecases,butmayalsohaveanadverseaffectonimagequality.
TheAxisproductsupportsthefollowingH.264prole(s):
•Baseline.TheBaselineproleisrecommendedforclientsthatdon’tsupportCABACentropycoding.
•Main.TheMainproleprovideshighercompressionwithmaintainedvideoqualitycomparedtotheBaselineprolebut
requiresmoreprocessingpowertodecode.
•High.TheHighproleprovidesreducedbitrateandhighercompressionwithmaintainedvideoqualitycomparedtothe
Mainprolebutrequiresmoreprocessingpowertodecode.
ThebitratecanbesetasVariablebitrate(VBR)orConstantbitrate(CBR).VBRadjuststhebitrateaccordingtotheimage
complexity,usingupmorebandwidthforincreasedactivityintheimage,andlessforlowerimageactivity.Whentheactivityin
thesceneincreases,thebitratewouldusuallyincreaseaswell.Ifthereisasurplusinbandwidth,thismaynotbeanissueand
selectingVariablebitrate(VBR)willbesufcient.Butifbandwidthislimited,itisrecommendedtocontrolthebitratebyselecting
Constantbitrate(CBR).Whentheactivityinthesceneincreases,VBRadjuststhebitrateaccordingtothecomplexity,usingup
morebandwidthforincreasedactivityinthescene,andlessforlowersceneactivity.CBRallowsyoutosetatargetbitratethat
limitsthebandwidthconsumption.
TheCBRtargetbitrateworksliketheceilingofatent.Itlimitsthebitrate,whilemaintainingsomeexibility.Thebitratemaybounce
upanddownwithinthesettargetbutwhenitnearsthesettargetvalue,thelimitationkicksin.However,becauseCBRwillalways
prioritizeacontinuousvideostream,itallowstemporaryovershootsfromthetargetbitrate.Becausesettingatargetvalueprevents
thebitratefromincreasing,framerateandimagequalityareaffectednegatively.Topartlycompensateforthis,selectwhichvariable
shallbeprioritized,framerateorimagequality.Notsettingaprioritymeansthatframerateandimagequalityareequallyaffected.
Thecurrentbitratecanbesettoappearastextoverlay.UnderOverlaySettings,selectIncludetextandenterthemodier
#bintheeld.
Toapplythesettings,clickSave.
Axis’ZipstreamTechnology
Zipstreamisabitratereductiontechnologyoptimizedforvideosurveillance.ZipstreamreducestheaveragebitrateintheH.264
streambyremovingunnecessarydataandmakesitpossibletoallowhigherresolutions,reducestoragecostortokeeprecordingsfor
alongertime.Toreducethebitrate,Zipstreamreducesthenumberofbitsintheareasoftheimagethatarelessinterestingfroma
videosurveillanceperspective,forexamplethebackground.Imagedetailsthatareimportantforforensicvideoanalysis,forexample
facesandlicenseplates,arepreservedwithenoughnumberofbits.
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