Axis P1428-E Uživatelský manuál stáhnout pdf (Strana 17)

AXISP1428–ENetworkCamera

Video

•Overlaysettings.SeeOverlayonpage20.

ClickSavetoapplythenewsettings.

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.

TheGOVlengthisthenumberofframesbetweentwoconsecutiveI-frames.IncreasingtheGOVlengthmaysaveconsiderablyon

bandwidthrequirementsinsomecases,butmayalsohaveanadverseaffectonimagequality.

TheAxisproductsupportsthefollowingH.264prole(s):

•Baseline.TheBaselineproleisrecommendedforclientsthatdon’tsupportCABACentropycoding.

•Main.TheMainproleprovideshighercompressionwithmaintainedvideoqualitycomparedtotheBaselineprolebut

requiresmoreprocessingpowertodecode.

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.

MJPEG

Sometimestheimagesizeislargeduetolowlightorcomplexscenery.Adjustingthemaximumframesizehelpstocontrolthe

bandwidthandstorageusedbytheMotionJPEGvideostreaminthesesituations.SettingtheframesizetotheDefaultsetting

providesconsistentlygoodimagequalityattheexpenseofincreasedbandwidthandstorageusageinlowlight.Limitingtheframe

sizeoptimizesbandwidthandstorageusage,butmaygivepoorimagequality.Topreventincreasedbandwidthandstorageusage,

themaximumframesizeshouldbesettoanoptimalvalue.

StreamProles

Astreamproleisasetofpredenedstreamsettingsincludingresolution,compression,framerateandoverlaysettings.Stream

prolescanbeused:

•Whensettinguprecordingusingactionrules.SeeEventsonpage32.

•Whensettingupcontinuousrecording.SeeContinuousRecordingonpage37.

•IntheLiveViewpage–selectthestreamprolefromtheStreamproledrop-downlist.

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