Axis Q3708-PVE - Page 17

AXISQ3708-PVENetworkCamera
Video
H.264
H.264,alsoknownasMPEG-4Part10/AVC,isavideocompressionstandardthatprovideshighqualityvideostreamsatlowbitrates.
AnH.264videostreamconsistsofdifferenttypesofframessuchasI-framesandP-frames.AnI-frameisacompleteimagewhereas
P-framesonlycontainthedifferencesfrompreviousframes.
TheH.264streamsettingscanbeconguredfromtheVideo>VideoStreampage.SelecttheH.264tab.Thesettingsdenedinthis
pagewillapplytoallH.264streamsthatdonotuseastreamprole.
TheGOPlengthisthenumberofframesbetweentwoconsecutiveI-frames.IncreasingtheGOPlengthmaysaveconsiderablyon
bandwidthrequirementsinsomecases,butmayalsohaveanadverseaffectonimagequality.
TheAxisproductsupportsthefollowingH.264prole(s):
•Baseline.TheBaselineproleisrecommendedforclientsthatdon’tsupportCABACentropycoding.
•Main.TheMainproleprovideshighercompressionwithmaintainedvideoqualitycomparedtotheBaselineprolebut
requiresmoreprocessingpowertodecode.
•High.TheHighproleprovidesreducedbitrateandhighercompressionwithmaintainedvideoqualitycomparedtothe
Mainprolebutrequiresmoreprocessingpowertodecode.
Toapplythesettings,clickSave.
MJPEG
Sometimestheimagesizeislargeduetolowlightorcomplexscenery.Adjustingthemaximumframesizehelpstocontrolthe
bandwidthandstorageusedbytheMotionJPEGvideostreaminthesesituations.SettingtheframesizetotheDefaultsetting
providesconsistentlygoodimagequalityattheexpenseofincreasedbandwidthandstorageusageinlowlight.Limitingtheframe
sizeoptimizesbandwidthandstorageusage,butmaygivepoorimagequality.Topreventincreasedbandwidthandstorageusage,
themaximumframesizeshouldbesettoanoptimalvalue.
Axis’ZipstreamTechnology
Zipstreamisabitrate-reductiontechnologyoptimizedforvideosurveillance.ZipstreamreducestheaveragebitrateintheH.264
streambyremovingunnecessarydataandmakesitpossibletoallowhigherresolutions,reducestoragecostortokeeprecordingsfor
alongertime.Toreducethebitrate,Zipstreamreducesthenumberofbitsintheareasoftheimagethatarelessinterestingfroma
videosurveillanceperspective,forexamplethebackground.Imagedetailsthatareimportantforforensicvideoanalysis,forexample
facesandlicenseplates,arepreservedwithenoughnumberofbits.
TheseZipstreamstrengthoptionsareavailable:
•Off.Zipstreamdisabled.
•LowestZipstreamstrength.Lowbandwidthreduction.Novisiblequalitydegradationinmostscenes
•MediumZipstreamstrength.Mediumbandwidthreduction.Limitedvisualqualitydegradationinnotprioritizedareasin
somescenes
•HighestZipstreamstrength.Highbandwidthreduction.Visiblequalitydegradationinnotprioritizedareasinmanyscenes
LowestZipstreamstrengthisthedefaultsettingfortheproduct.Thiscongurationisverysafetouseinallapplicationswhilestill
reducingthebitrate.
Forcloud-connectedcamerasorcamerasusingedgestoragethatneedtolimitthebitrateforincreasedstoragetimeitis
recommendedtoselecttheHighestZipstreamstrength.Thissettingisverygoodtocombinewithmotiondetectiontriggeringand
variablebitrate(VBR)wherethebitrateisallowedtoadapttochangesincomplexityinthescene.
Axis’ZipstreamTechnologyforH.264conformstotheH.264standardandiscompatiblewiththird-partyclientsandVMSsolutions
thatdecodeH.264video.
ThebitratecontrollerbuiltintotheproductcanbecombinedwithZipstreamtoenforceamaximumbitrate(MBR)limit.Axis
CommunicationsrecommendsusingVBRorMBRwitharatherhighbitratelimittoenablethefullpotentialofAxis’Zipstream
Technology.
17