Machine-type
detection
Observed KPI
values
Expected
KPI values
M-QoE prediction
Gaps
(M-QoE quantification)
Induced subscriber/vertical
KPI gaps
Device traffic
Vertical KPI
Subscriber KPI
Application-type
inference
Machine learning
ERICSSON
TECHNOLOGY
C H A R T I N G T H E F U T U R E O F I N N O V A T I O N I # 1 0 ∙ 2 0 2 0
VERSATILE
VIDEO CODING
EXPLAINED

Many new and emerging 5G use cases will soon require video
compression efficiency and functionality that are beyond the capabilities
of today’s leading video codecs. Versatile Video Coding – the new video
compression coding standard recently approved by the Moving Picture
Experts Group and the International Telecommunication Union – includes
both improved compression efficiency and new features to enhance
support for immersive video and low-delay video coding.
RICKARD SJÖBERG,
JACOB STRÖM,
ŁUKASZ LITWIC,
KENNETH ANDERSSON
The latest Ericsson Mobility Report estimates
that video accounted for 63 percent of the
traffic in mobile networks during 2019 and
that this share will increase to 76 percent by
2025 [1]. Enabled by continuously improving
network performance, this growth is driven
by the ever-increasing availability of video
content in streaming services and online
apps, and by changing consumer behavior
toward consumption of the content on mobile
devices. The evolution toward large screens
with high resolutions beyond HD on mobile
devices further raises consumer expectations
regarding the quality of delivered video
content. Video codecs play a critical role
in coping with these expectations.
■ While the quality of video content depends on
several characteristics such as high pixel bit depth,
high frame rate, wide color gamut (WCG) and high
dynamic range (HDR), it is the resolution (the
number of pixels in a video picture) that is most
directly associated with the bandwidth required
for transmission. Other key factors determining
the required bandwidth are related to the type
of the video content and the latency with which
the content is delivered to the end user.
Atthesametime,innovationsin5Gnetworks
offernewopportunitiesforvideo-enabledservices
forbothconsumers(remotelyrenderedvirtual/
extendedrealityandcloudgaming,forexample)
andindustries,particularlywithrespecttothe
InternetofThings(IoT)andtheautomotivesector.
VersatileVideo
Codingexplained
– THE FUTURE OF VIDEO IN A 5G WORLD
✱ VERSATILE VIDEO CODING
2 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020

Thesenewservicesareexpectedtorelyon
continuedvideoevolutiontoward8Kresolutions
andbeyond,andonnewstrictrequirementssuchas
lowend-to-endlatencyforvideodelivery.Sincethe
datarateofsuchvideo-enabledservicesisextremely
high,thecostwouldbeprohibitive–eveninthemost
modernnetworks–unlessthevideowascarried
inacompressedformat,withthehelpofanext
generationvideocodec.
VersatileVideoCoding(VVC),thenewvideo
compressioncodingstandardthatwillbepublished
asISO/IEC23090-3andITU-Trecommendation
H.266,offersthehighestcompressionefficiency
availabletodayandisthereforethecodecthatis
bestsuitedtoofferasuitableperformancelevelfor
newmediaservicesover5Gnetworks.Itcanalso
enhancetheuserexperienceforexistingvideo
servicesbydeliveringsubstantiallyhigherquality
atthesamebitrate.
Alternatively,itcanbeusedtoreducethebitrate
(roughlybyhalf)whilemaintainingthesamequality.
Forsomelegacyapplications,thecostofreplacingan
oldercodecsuchasH.264withaneweronesuchas
HEVChasnotbeeneconomicallybeneficial,
sincethereductioninbitrateof40percenthasnot
compensatedforthecostofreplacingalargenumber
ofsettopboxes.Eveninsomeofthesecases,the
introductionofVVCmaychangethiscalculation
sincethebitratereductioncomparedtotheolder
codecissomuchgreater.Figure1providesan
overviewofpotentialapplicationareas.
Videocompressionoptionsavailabletoday
Avideocodec,whichcanbeimplementedin
hardwareorsoftware,encodesand/ordecodes
digitalvideo.Modernvideocodecscanreducethe
bitrateofuncompressedvideotolessthanone
percentoftheoriginalratewithoutanynoticeable
visualqualitydegradations.Themajorityofthese
videocodecshavebeenstandardizedandpublished
byastandardsdevelopmentorganization(SDO).
Themostpopularandwidelydeployedcodecs
includetheMPEG(MovingPictureExpertsGroup)
seriesfromISO/IEC(InternationalOrganization
forStandardization/InternationalElectrotechnical
Commission)andthecorrespondingH.26xseries
Figure 1 VVC application areas
Versatile
Video
Coding
High-quality
HD and 4K
video streaming Enhancing
existing
services
Enabling
new
services
Telepresence
and screen
sharing
8K HDR video
streaming
Low-latency
cloud gaming
Immersive XR
and telepresence
IoT and
automative
360-video
VR streaming
VERSATILE VIDEO CODING ✱
OCTOBER 14, 2020 ✱ ERICSSON TECHNOLOGY REVIEW 3

fromtheITU-T(ITUTelecommunication
StandardizationSector),whichweredeveloped
jointly.Thenamingconventionforthesecodecsis
MPEG-2/H.262,AVC/H.264(AdvancedVideo
Coding)andHEVC/H.265(HighEfficiencyVideo
Coding).Othervideocodecoptionsinclude
Google’sVP8andVP9,andtheAllianceforOpen
Media’sAV1.
MPEG-2/H.262
TheMPEG-2videocodecwaspublishedin1994
andisstillinwideusetodayinstandarddefinition
digitalTVservices.Itscompressionefficiencyislow
whencomparedwithmorerecentvideocodecs.
ThemainreasonforusingMPEG-2todayisto
supportexistingset-top-boxes,asthecostof
replacingthesemaybehigherthananypotential
savingsfromanewvideocodec.
AdvancedVideoCoding
AVC/H.264waspublishedin2003andiscurrently
themostwidelyusedvideocodec.Itissupportedby
practicallyallmobiledevices,isheavilyusedfor
videocarriedovertheinternet,andisthepreferred
videocodecforHDTV.
HighEfficiencyVideoCoding
HEVC/H.265[2]isthesuccessortoH.264andwas
publishedin2013.ComparedwithH.264,itdelivers
thesamevisualqualityatroughly40percentlower
bitrate.ThereiswidespreadsupportforHEVC
acrossTVsandmobiledevices.HEVChasbeen
selectedbytheDVB(DigitalVideoBroadcasting)
andATSC(AdvancedTelevisionSystems
Committee)standardsorganizationsfor4K
broadcastservicesandisrecommendedby3GPP
forHD(HDR)and4Kmobilestreaming.
VP8andVP9
On2Technologies,whichwasacquiredbyGoogle
in2010,releasedtheVP8videocodecin2008,
whichthenbecameaproposedroyalty-freeoption
in2013.Ithasmostlybeenusedasanalternative
toH.264inWebRTC,aframeworkforreal-time
webcommunication.VP9,asuccessortoVP8,
wasdevelopedinternallyatGoogleandreleasedas
opensourceinlate2012.TheuseofVP9for4K
YouTubevideoshasledtoTVmanufacturers
incorporatingVP9decodingintovirtuallyall4K
TVsets,therebyspreadingsupportofVP9
toasubstantialnumberofdevices.
AV1
In2015,agroupofcompaniesincludingAmazon,
Facebook,Google,Intel,MicrosoftandNetflix
foundedtheAllianceforOpenMedia(AOMedia)
withtheaimofdevelopinganewroyalty-freevideo
codec.Thespecificationforthatcodec,AV1,was
publishedonJanuary8,2019.Althoughpatent
reviewswereconductedduringthedevelopmentto
avoidinfringingonthird-partyintellectualproperty
rights,thepatentlicensingorganizationSisvel
announcedinMarch2019thatitwouldforma
patentpoolforAV1.Asaresult,theroyalty-free
statusofAV1isuncertain.
VersatileVideoCoding–thedevelopment
process
VersatileVideoCoding(H.266)wasstandardized
inajointeffortbytheVideoCodingExperts
GroupoftheITU-TandMPEGoftheISO/IECand
isthereforethelatestmemberofasuccessfulfamily
ofvideocodecsthatincludesMPEG-2,
H.264andHEVC.Incontrasttoproprietary
alternatives,allfourofthesevideocodingstandards
weredevelopedinanopenandcollaborative
fashionwithagreedrequirementsandtimelines.
ThedevelopmentofVVCfolloweda
well-establishedstandardizationprocess,
whichstartedwithatechnologyexplorationactivity
in2015,includedaformalcallforproposalsin2018
andconcludedinJuly2020asatechnicallyfrozen
standard.Thedevelopmentprocessinvolved
internationalstakeholdersacrosstheentiremedia
ecosystem:contentproducers,manufacturers,
VVCISTHELATEST
MEMBEROFASUCCESSFUL
FAMILYOFVIDEOCODECS
✱ VERSATILE VIDEO CODING
4 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020

operators,broadcasters,chipsetvendorsand
academics.Throughouttheprocess,all
documentationincludingtechnicalcontributions,
draftspecificationtext,referencesoftwareand
conformancebitstreamsweremadeavailable
publicly.
Ericssonhasbeenanactiveparticipantinvideo
standardizationformorethan20yearsandwas
closelyinvolvedinthedevelopmentoftheVVC
standard.Throughouttheprocess,weledseveral
ofthecoreexperiments,chairedad-hocworking
groupsandmadesignificantcontributionstothe
developmentofthetechnologybehindthevideo
codec,mostnotablyintheareasofdeblocking
filtering,referencepicturemanagement,low-delay
videocodingandoptimizedencoderconfigurations.
Wealsoparticipatedineffortsthatmadeanimpact
inotherareasofthevideocodecsuchasintra
andinterpredictionandadaptiveloopfiltering.
Keybenefitsofversatilevideocoding
Asthelatestandmostsophisticatedvideocodecto
date,VVCoffersthehighestcompressionefficiency
ofallvideocodecs,anditisparticularlyappropriate
forhigherresolutionvideostreamsduetoits
codingtools,whichcanoperateonblocksizes
ofupto128x128pixelsandwith64x64samplesize
transforms.VVCcanachieveareductioninbitrate
ofaround40percentforexistingHDand4K
servicesdeployedwithHEVC,atthesame
visualquality.
Figure2providesaperformancecomparison
betweenVVCandfourothervideocodecs.
ThecomparisonwasdonebyEricssonResearch
usingvarioussourcesofinformationincluding
in-housetesting[3,4].Thefigureshowsthe
approximaterelativebitraterequirementforeach
videocodecinordertoreachthesamevideopicture
qualityforHDand4Kcontent,benchmarked
againsttheHEVCvideocodec,whichisnormalized
to100percent.VVCperformssignificantlybetter,
requiringonly60percentoftherelativebitrate
comparedwith bothHEVCandAV1.
Ontopofitssuperiorcompressionperformance,
theversatilityofVVCalsomakesitanattractive
choicebeyondmainstream2Dvideoservices.
VVChasbeendesignedtohandlebothtraditional
camera-capturedcontentaswellastheincreasingly
VERSATILE VIDEO CODING ✱
OCTOBER 14, 2020 ✱ ERICSSON TECHNOLOGY REVIEW 5
Figure 2 Relative bitrates for the same video quality
180%
160%
140%
120%
100%
80%
60%
40%
20%
0%
170%
Relative bitrates for the same video quality (lower is better)
H.264 VP9 HEVC AV1 VVC
120%
100% 100%
60%

prevalentcomputer-generatedimageryusedin
applicationssuchasonlinegaming,e-sportsvideo
streamingandscreen-sharingapplications.
Immersivevideo
Incontrasttotraditionaltwo-dimensionalvideo,
whereoneparticularviewiscapturedbyacamera,
immersivevideoisvideoinwhicheveryangleis
recorded.Duringplayback,whichatpresent
typicallyoccursonavirtualreality(VR)headset,
theuserisnotconstrainedtoaparticularviewbut
canlookaroundfreely.Whentheviewerdoesnot
changeposition,thisiscalledthreedegreesof
freedom(3DoF)immersivevideo,ormore
commonly360-degreevideo.
360-degreevideoistypicallystoredina
projectionformat.Onesuchformatis
equirectangularprojection,whichissimilar
tohowtheearthispicturedonaworldmap.
Amorepopularformat,however,iscubemap
projection.Here,eachfaceofthecuberepresents
one-sixthofthespherearea,andthesixfaces
arearrangedinonerectangularvideopicture.
Thisenablestheuseoftwo-dimensionalvideo
codecstohandletheimmersivecontent.
Duetothenatureofthehumanvisualsystem,
ahigh-qualityrepresentationofthefull360-degree
videosphereisonlyneededfortheuser’scurrent
gazedirection.Awell-knowntechniquefor
exploitingthispropertyistosplitthefull360-degree
videocontentintomultiplesmallrectangularregions
andonlyconveyandrenderregionsinhighquality
thatcovertheareatheuseriscurrentlylookingat,
calledtheviewport.Toaccommodatefasthead
motion,videoisalsotransmittedforthe
non-viewportarea,butthequalityofthat
videoismuchlower.
Tothatend,andtohelpwithotherimmersive
videoapplicationssuchasremotelyrenderedVR,
VVCintroducestheconceptofsubpictures,which
allowsfortheefficientextractionandmerging
ofpiecesofvideoofdifferentqualitythatisa
requirementforlargerresolutionimmersiveformats.
Asubpictureisarectanglewithinthefullvideo
picturethatisfullyindependentofothersubpictures
anddesignedtobeeasytoextractandmergewith
othersubpictures.Previousvideocodecsprovided
similarfunctionalityusingmotion-constrainedtile
sets,butsubpicturesarebothmuchmoreefficient
andeasiertomanage.
Theefficiencyofthesubpicturedesigncomes
frombuilt-inadjustmentsoflow-levelcodingtools,
wherepreviousdesignsrequiretheencoderstobe
veryrestrictive.Previousdesignsalsorequire
rewritingofsubstantialamountsofcodeddata–
aburdenthatislargelyalleviatedbytheuseof
subpicturesinVVC.TheuseofsubpicturesinVVC
significantlyreducesthecomplexityofapplication
systems.Thiscapability,togetherwithitssuperior
compressionefficiency,makesVVCthebestvideo
codecchoiceforimmersivevideoapplications.
Low-delayvideocoding
Low-delayvideocodingisakeytechnologyfor
certaintime-criticalvideoapplicationssuchas
videoconferencing,cloudgamingandremote
controlofroadvehiclesanddrones.Toreducethe
latencycausedbyexcessivedatabuffering,thevideo
encodertypicallyaimstogenerateassmoothadata
rateaspossible.Onewell-knownvideocodec
featureisgradualdecodingrefresh(GDR),
whichprovidessmoothtune-inpointsinthe
bitstreamwithouttheneedtoencodesingle
refreshpictures(intrapictures)thatresultin
bitratespikesandhighlatencies.Instead,smooth
tune-inpointsaregeneratedbyspreadingthe
refreshacrossmultiplepictures.
GDRhasbeensupportedinmanyoldervideo
codingstandardssuchasH.264andHEVC,butin
thosecasesthefeatureisconveyedinasupplemental
enhancementinformation(SEI)message,which
makesGDRoptional.Thismeansthatanencoder
cannotbecertainthatthedecodersarecapable
THEUSEOFSUBPICTURES
INVVCSIGNIFICANTLY
REDUCESTHECOMPLEXITY
OFAPPLICATIONSYSTEMS
✱ VERSATILE VIDEO CODING
6 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020

oftuninginatGDRpositions.However,during
standardizationofVVC,anEricssonproposalto
addaGDRpicture-typeindicatortothestandard
wasadopted.ThismakesGDRsupportmandatory
inVVC,whichensuresdecoderinteroperability
forsuchlow-delayapplications.
BesidestheGDRfeature,VVCalsoinherited
decodingunit(DU)baseddecoderoperationfrom
itspredecessor,HEVC.DUsenableanencoderto
outputafirstpartofapicture,inaspecified
controlledmanner,withoutrequiringtheentire
picturetofirstbeencoded.DUsandmandatory
GDRsupportmakeVVCtheprimevideocodec
choiceforlow-delayvideoapplications.
HowVVCworks
Itisimportanttonotethatthesuperiorcoding
efficiencyofVVCisnotduetoanysingle
compressiontool.Rather,itistheresultofcombining
manytools,eachcontributingwithasmall
compressionimprovement.Themostsignificant
ofthesetoolsareblockpartitioning,advancedinter
prediction,dependentquantization,adaptive
loopfilteringandimproveddeblockingfiltering.
Theadditionofsophisticatednewcodingtools
hasalsohadanimpactoncomputationalcomplexity.
Asaresultofthesedevelopments,itisexpectedthat
VVCdecodercomplexitywillbearoundtwicethat
ofHEVC.
Blockpartitioning
Similartoitspredecessors,VVCusesablock-based
hybridcodingarchitecture.Avideocodecbasedon
suchanarchitecturedoesnotcodepixelvalues
directlybutinsteadpredictsandcodesonlyerror
informationtocompensatefortheinaccurate
prediction.Theprocessrunsonblocksofpixels
ratherthantheentirepicture,sincethismakesit
possibletoadjusttolocalvideopicture
characteristics,minimizingthepredictionerror.
Forvideocodecsbasedonsuchanarchitecture,
anefficientpicturepartitioningschemeispivotal
toachievinghighcompressionefficiency.
InVVC,eachpictureissplitintonon-overlapping
squarescalledcoding-treeunits(CTUs).Thelargest
CTUsizeallowedinVVCis128x128pixels,larger
thanthe64x64maximumsizeallowedinHEVC.
Largeblocksimprovetheefficiencyofcoding
flatareassuchasbackgrounds,especiallyfor
high-resolutionvideossuchasHDand4K.
Inordertoefficientlyrepresenthighlydetailed
areassuchastexturesandedges,VVCemploys
aflexiblepartitioningschemethatcanpartition
128x128-sizedCTUsdowntocodingunits(CUs)
assmallas4x4pixels.
Theschemeisbasedontwoparts.Thefirstisthe
quaternarytree(quadtree)splitthatisalsoavailable
inHEVC,whichcanrecursivelysplitCTUinto
squaredCUsdownto4x4pixels,smallerthanthe
8x8minimumCUsizeinHEVC.Thesecondpart
consistsofbinary-treeandternary-treesplitsthat
partitionablockintotwoandthreerectangles
respectively.Bothbinaryandternarytreesplits
canoperateineitherhorizontalorvertical
directions,berecursivelyappliedandmixed
togetherinanestedmulti-typetree.
Terms and abbreviations
3DOF – Three Degrees of Freedom | ALF – Adaptive Loop Filter | CTU – Coding-Tree Unit | CU – Coding
Unit | DU – Decoding Unit | DVB – Digital Video Broadcasting | GDR – Gradual Decoding Refresh |
HDR – High Dynamic Range | HEVC – High Efficiency Video Coding | IEC – International Electrotechnical
Commission | IETF – Internet Engineering Task Force | ISO – International Organization for Standardization
| ITU– International Telecommunication Union | ITU-T – ITU Telecommunication Standardization Sector |
MPEG – Moving Picture Experts Group | SDO – Standards Development Organization | UHD – Ultra High
Definition | VR – Virtual Reality | VVC – Versatile Video Coding | XR – Extended Reality
VERSATILE VIDEO CODING ✱
OCTOBER 14, 2020 ✱ ERICSSON TECHNOLOGY REVIEW 7

Figure3providesanexampleofthepartitioning
ofaclose-upsectionofapicture.HEVCblock
partitioning(attopright)usesquaternary-treesplit
withcodingblocksupto64x64pixels.VVCblock
partitioning(atbottomright)usesquaternary-tree
splitwithcodingblocksupto128x128pixelsand
nestedmulti-typetreesplitemployingbinaryand
ternarytreesplits.
TheblockpartitioninginVVCishighlyflexible
andprovidesabout8percentbitratereductionover
HEVC[5].However,thisflexibilitycomesata
computationalcost,especiallyontheencoderside,
wheremanymorepermutationsneedtobe
evaluatedtoselecttheoptimalpartition.
Advancedinterprediction
Oneofthemostefficientbit-savingtechniquesin
videocompressionisinter-pictureprediction(more
commonlyreferredtoasinterprediction),which
simplymeanscopyingsamplevaluesfrompreviously
codedpictures.Theinformationaboutwhereto
copyfrom–thehorizontalandverticaldisplacement
forablock–isstoredinwhatiscalledamotion
vector.Techniquesthatimproveinterpredictionare
responsibleforasubstantialpartofthebitrate
reductionbetweenVVCandHEVC.
Whilemanytechniqueshavebeenusedtoachieve
theadvancedinterpredictioninVVC,fiveofthem
areparticularlynoteworthy:theaffinemotion
model,adaptivemotionvectorresolution,
bi-directionalopticalflow,decoderside-motion
vectorrefinementandgeometricpartitioningmode.
Theprecisionofthemotionvectorshasalsobeen
increasedto1/16pixelcomparedtothequarterpixel
resolutionofHEVC.
Inpreviousvideocodingstandards,ithasbeen
possibletocompensatefortranslationalmotion;
thatis,thedecodercanbeinstructedtofetchsample
valuesnotfromthesameplaceinapreviousimage
butratherfromanotherposition(1.75pixelstothe
left,forexample).InVVC,theaffinemotionmodel
toolmakesitpossibletospecifynotonlydistance
180%
160%
140%
120%
100%
80%
60%
40%
20%
0%
170%
Relative bitrates for the same video quality (lower is better)
H.264 VP9 HEVC AV1 VVC
120%
100% 100%
60%
Figure 3 Comparison of the partitioning of a close-up section of a video picture in HEVC and VVC
✱ VERSATILE VIDEO CODING
8 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020

butalsorotationandzoom,whichcansavealotof
bitsforsequencescontainingsuchmotion.
Anotherbit-savingtechniqueinVVCisthe
abilitytovarytheprecisionofthemotionvectors.
Forexample,theencodercansignaltothedecoder
thattheincomingmotionvectorsareinintegeror
four-times-integerresolution.Thiscansavebits
whenpredictingsmoothareaswheretheexact
sub-pixelprecisiondoesnotgivemuchimage
improvementoverintegerprecisionandalso
whenrepresentinglargemotionvectors.
TheadvancedinterpredictioninVVCfurther
exploitsthefactthatinsomecasesmotion
informationdoesnothavetobeexplicitly
transmitted(asmotionvectors)butcaninsteadbe
inferredfromsimilarlymovingpartsofthepicture.
Forexample,thebi-directionalopticalflowtool
inVVCcaninfermotionvectorsbymeasuring
theopticalflowinreferencepicturesandthe
decoderside-motionvectorrefinementcaninfer
motionvectorsbyminimizingdifferencesbetween
referencepictures.
Finally,theadvancedinterpredictioninVVC
alsoexploitsmotionsofnon-rectangularshapes
tobetteralignwiththeshapeofmovingobjects.
Thismeansthatonehalfoftheblockcanhave
onemotionvectorandtheotherhalfoftheblock
canhaveanotherwiththehalvesseparatedbya
singlegeometricallinethatisdeterminedbyan
angleandanoffset.
Dependentquantization
Thequantizerisacorepartofavideocodecthat
isdirectlylinkedtooperationalcontrolofvideo
bitrateandvisualquality.Byadjustingthe
quantizationstep,theencodercontrolsthefidelity
oftheerrorsignal(transformcoefficients),whichis
thencodedwithanentropycoderandsentinthe
videobitstream.
PreviousstandardssuchasHEVChaveused
ascalarquantizerbutsincetheentropycoder
processeseachtransformcoefficientinacoding
blockinsequentialorder,therewasaninherent
inefficiencyifthequantizationlevelofeach
coefficientweretobedeterminedindependently.
Tooptimizethedeterminationofquantization
levelswithinablock,sophisticatedencoders
useanalgorithmcalledtrellisquantization.
InVVC,dependentquantizationhasbeen
introduced,wherethecodeccanswitchbetween
twoshiftedquantizersandtherebyreducethe
quantizationerror.IntheVVCdesign,the
quantizationlevelsforagiventransformcoefficient
dependonthevaluesoftheprecedingquantized
coefficients.Tousethistooleffectively,anencoder
thereforeneedstoevaluatehowthedetermined
quantizationlevelforeachcoefficientimpacts
boththebitcountandthetotalreconstruction
errorforthewholeblock.Inthisway,thedependent
quantizationremovestheinefficiencyofquantizing
coefficientsindependentlyandtherebyprovides
asubstantialbit-reductionoverHEVC.
Adaptiveloopfiltering
Theadaptiveloopfilter(ALF)isanewin-loopfilter
inVVC.ALFscansthepictureafterithasbeen
decodedandselectivelyapplies(onaCTUbasis)
oneofseveraltwo-dimensionalfiniteimpulse
responsefiltersbeforethepicturebecomesoutput
orisusedforprediction.Thevideoencoder
calculatesthesetsoffiltercoefficientsthatwill
leadtothesmallesterrorandtransmitsthoseto
thevideodecoder.ALFhastheabilitytocleanup
artifactsinthepictureandalsocontributestoa
substantialbit-reductionoverHEVC.
Improveddeblockingfiltering
VVCanditspredecessorsHEVCandH.264
areallblock-basedvideocodecs.Thedownside
oftheblock-basedapproachisthatitcangiverise
to“blockartifacts”–visibleedgesatsomeblock
borders.Deblockingfilteringisanapproachto
reducetheseartifactsbyselectivelysmoothing
DEPENDENTQUANTIZATION
REMOVESTHEINEFFICIENCY
OFQUANTIZINGCOEFFICIENTS
INDEPENDENTLY
VERSATILE VIDEO CODING ✱
OCTOBER 14, 2020 ✱ ERICSSON TECHNOLOGY REVIEW 9

acrosstheblockboundaries.Thedeblocking
filteringinVVCisbasedontheHEVCdeblocking
filtering,forwhichEricssonwastheleading
contributor.Ontopofthisalreadystrongbase,
VVCiscapableofusinglongerdeblockingfilters,
wheremajorpartsweredesignedbyEricsson.
Thelongdeblockingfiltersallowforstronger
deblockingthatcanbemoreeffectiveinhiding
blockartifacts,especiallyforlargerblocks
(128x128sizedblocks,forexample)inrelatively
smoothareas.Thelongdeblockingfilterscontribute
significantlytotheimprovedsubjectivequality
ofVVCcomparedtoHEVC.
What’snextforVVC?
Intoday’scompetitivevideocodeclandscape,video
compressionperformanceiskeytosuccessful
marketadoption,butitisnotthesoledetermining
factor.Availabilityofthetechnologyiscritical,
especiallytheavailabilityofhardware-accelerated
decodersinchipsetsandprocessors.Arecent
predictionfromamajorchipsetvendorstatedthat
firstcommercialVVCshipmentscouldstartassoon
as2021.Software-basedsolutionsaretypicallyfaster
torolloutandareessentialespeciallyintheearly
phasesofdeploymentacrosstheecosystem.Inthe
caseofVVC,thefirstdemonstrationsofreal-time
softwaredecoderstookplaceshortlybeforethe
standardwascompleted.
Sincevideocodecsdonotoperateinasilo,
supportandinteroperabilityacrosstheecosystem
intermsofmediadeliveryprotocolsandapplication
specificationsarerequired.SomeoftheSDOs
suchasMPEGandIETFarelookingintoproviding
supportforcarriageofVVCintheirrespective
mediatransportspecifications.Organizations
suchas3GPPandDVBareinvestigatingVVC
inthecontextofnext-generationservicesincluding
5G-enabledonessuchas8K(7680x4320video)
and360-degreevideoVRstreaming.Unlikeits
predecessors,thefirstversionoftheVVCstandard
includessupportforabroadrangeofapplications
acrossthemediaecosystem,whichislikelytohave
apositiveimpactonthecostofdeploymentand
interoperabilityofVVC-basedsolutionsand
services.
Inordertofacilitatecross-industrydiscussion
aroundnon-technicalaspectsofVVCdeployment
suchaslicensing,marketingandinteroperability
activities,Ericssonandotherindustryleaders
launchedtheMediaCodingIndustryForum
(MC-IF)in2018.Sincethen,MC-IFhashosteda
seriesofworkshopsandeventstogatherwider
industryinputoncommercialaspectsthatmay
furtherearlyVVCadoption.Inparticular,timely
availabilityoflicensingtermsforVVCwas
establishedasoneofthekeyfactorsforVVC
deployment.Tothisend,shortlyafterthefinalization
ofVVCdevelopment,MC-IFinitiatedfostering
effortsforapatentpoolprogramessentialtoVVC.
Conclusion
VersatileVideoCodingrepresentsstate-of-the
artvideocodingandiscertaintoplayanimportant
roleinsupportingawiderangeof5Gusecases.
Designedtomanagethehighdemandthat
increasingamountsofvideoposesonnetworks,
ourresearchrevealsthatVVCachievesthebest
availablecompressionperformanceata
computationalcomplexitysuitablefor
implementationinbothsoftwareandhardware.
AsoneofthemaincontributorstoVVC,webelieve
itsdeploymentwillsignificantlyreducethe
dataratesofexistingvideoservicesaswellas
servingasaprimaryenablerfornext-generation
mediaservices.
THELONGDEBLOCKING
FILTERSCONTRIBUTE
SIGNIFICANTLYTOTHE
IMPROVEDSUBJECTIVE
QUALITYOFVVCCOMPARED
TOHEVC
✱ VERSATILE VIDEO CODING
10 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020

Further reading
❭ Ericsson blog, Cutting the bitrate with Versatile Video Coding, available at: https://www.ericsson.com/en/
blog/2019/7/mpeg-cut-the-bitrate-versatile-video-coding
❭ Ericsson blog, Industry Forum to promote Versatile Video Coding, available at: https://www.ericsson.com/
en/blog/2018/9/industry-forum-to-promote-versatile-video-coding
References
1. Ericsson Mobility Report, June 2020, available at: https://www.ericsson.com/en/mobility-report/reports/
june-2020
2. Ericsson Technology Review, Next generation video compression, April 24, 2013, Fröjdh, P; Norkin,
A; Sjöberg, R, available at: https://www.ericsson.com/en/reports-and-papers/ericsson-technology-review/
articles/next-generation-video-compression
3. 2019 Picture Coding Symposium (PCS), Ningbo, China, 2019, pp. 1-5, Compression Performance of the
Versatile Video Coding: HD and UHD Visual Quality Monitoring, Sidaty, N. et al., available at:
https://ieeexplore.ieee.org/document/8954562/authors#authors
4. ResearchGate, SMPTE Motion Imaging Journal, vol. 128, no. 10, pp. 14-24, Nov.-Dec. 2019, Analysis
of Emerging Video Codecs: Coding Tools, Compression Efficiency and Complexity, J. L. Tanou and M.
Blestel, available at: https://www.researchgate.net/publication/332073033_Analysis_of_Emerging_Video_
Codecs_Coding_Tools_Compression_Efficiency_and_Complexity
5. IEEE Transactions on Circuits and Systems for Video Technology, vol. 30, issue 5, pp. 1311-1325, May
2020, doi: 10.1109/TCSVT.2019.2945048, A VVC Proposal With Quaternary Tree Plus Binary-Ternary
Tree Coding Block Structure and Advanced Coding Techniques, Y. Huang et al., available at:
https://ieeexplore.ieee.org/document/8859290
VERSATILE VIDEO CODING ✱
OCTOBER 14, 2020 ✱ ERICSSON TECHNOLOGY REVIEW 11

theauthors
✱ VERSATILE VIDEO CODING
12 ERICSSON TECHNOLOGY REVIEW ✱ OCTOBER 14, 2020
Rickard Sjöberg
◆ is an expert in video
compression at Ericsson
Research where he currently
works as a technical lead in
video coding research.
He joined Ericsson in 1996
and has contributed several
hundred proposals for
the ITU-T and MPEG
video-coding standards.
In addition, he has worked
in product development
related to video coding
at Ericsson, including six
months at Ericsson
Television in Southampton
in the UK. Sjöberg holds an
M.S. in computer science
from KTH Royal Institute
of Technology in Stockholm,
Sweden.
Jacob Ström
◆ is a principal researcher
at Ericsson Research with a
focus on video compression.
He joined Ericsson in 2001
and has contributed to
standardization in the area of
high dynamic range video as
well as to the standardization
of both HEVC and VVC.
He is coauthor of more than
120 granted patents and has
a similar number of patents
pending. Ström holds a Ph.D.
in image coding from
Linköping University,
Sweden, and has been a
visiting Ph.D. student at the
University of California
San Diego and the
Massachusetts Institute of
Technology (MIT) in the US.
Łukasz Litwic
◆ is a research leader at
Ericsson Research. He joined
Ericsson Television in 2007,
where he worked on various
aspects of image processing
and video compression
research, which formed
the foundation of Ericsson
real-time broadcast
encoding products. In 2017,
he joined Ericsson Research
in Stockholm, Sweden,
where he leads the
Visual Technology team.
He holds an M.S. from
Gdansk University of
Technology, Poland, and a
Ph.D. from the University of
Surrey, in Guildford in the UK.
Kenneth Andersson
◆ is a senior specialist in
video coding at Ericsson
Research. He joined Ericsson
in 1994 to work on speech
coding and since 2005 has
been active in video coding
standardization in ITU-T
and ISO/IEC for
development of HEVC
and VVC. He holds an M.Sc.
in computer science and
engineering from Luleå
University in Sweden
and a Ph.D. from Linköping
University.

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