Axis Q7411 - Stream Profiles

AXISQ7411VideoEncoder
VideoandAudio
•Maximumframerate.Toavoidbandwidthproblems,theframerateallowedtoeachviewercanbeLimitedtoaxed
amount.Alternatively,theframeratecanbesetasUnlimited,whichmeanstheAxisproductalwaysdeliversthehighest
frameratepossibleunderthecurrentconditions.
•Overlaysettings.SeeOverlayonpage21.
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.
TheGOPlengthisthenumberofframesbetweentwoconsecutiveI-frames.IncreasingtheGOPlengthmaysaveconsiderablyon
bandwidthrequirementsinsomecases,butmayalsohaveanadverseaffectonimagequality.
TheAxisproductsupportsthefollowingH.264prole(s):
•Baseline.TheBaselineproleisrecommendedforclientsthatdon’tsupportCABACentropycoding.
•Main.TheMainproleprovideshighercompressionwithmaintainedvideoqualitycomparedtotheBaselineprolebut
requiresmoreprocessingpowertodecode.
ThebitratecanbesetasVariablebitrate(VBR)orMaximumbitrate(MBR).VBRadjuststhebitrateaccordingtotheimage
complexity,usingupmorebandwidthforincreasedactivityintheimage,andlessforlowerimageactivity.Whentheactivityin
thesceneincreases,thebitratewouldusuallyincreaseaswell.Ifthereisasurplusinbandwidth,thismaynotbeanissueand
selectingVariablebitrate(VBR)willbesufcient.Butifbandwidthislimited,itisrecommendedtocontrolthebitratebyselecting
Maximumbitrate(MBR).Whentheactivityinthesceneincreases,VBRadjuststhebitrateaccordingtothecomplexity,usingup
morebandwidthforincreasedactivityinthescene,andlessforlowersceneactivity.MBRallowsyoutosetatargetbitratethat
limitsthebandwidthconsumption.
TheMBRtargetbitrateworksliketheceilingofatent.Itlimitsthebitrate,whilemaintainingsomeexibility.Thebitrate
maybounceupanddownwithinthesettargetbutwhenitnearsthesettargetvalue,thelimitationkicksin.However,because
MBRwillalwaysprioritizeacontinuousvideostream,itallowstemporaryovershootsfromthetargetbitrate.Becausesettinga
targetvaluepreventsthebitratefromincreasing,framerateandimagequalityareaffectednegatively.Topartlycompensatefor
this,selectwhichvariableshallbeprioritized,framerateorimagequality.Notsettingaprioritymeansthatframerateand
imagequalityareequallyaffected.
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.SeeEventsonpage39.
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