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Overview of the H. 264/AVC video coding standard
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Overview of the H. 264/AVCvideo coding standard
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History and Naming
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Goal of “The Standard
! "e#lo$ over e%isting & f't're networ(s in
these areas with s')stantiall$ low )itrate* + ,roadcast
+ -nteractive or serial storage + Conversational services
+ Videoondeand or 'ltiedia streaing services
+ 0'ltiedia essaging services
! 1le%i)ilit$ and C'stoia)ilit$*
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Co#arison* 3S5
! H.264 i#roves the coding efficienc$ over othercoding ethods
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"esign 1eat're Highlights
! nhanceents of coding efficienc$ + ,etter #rediction
! Varia)le )loc(sie otion co#ensation with sall )loc( sies
! 7'artersa#leacc'rate otion co#ensation
! 0'lti#le reference #ict're otion co#ensation
! 8eighted #rediction
+ Other factors! Hierarchical )loc( transfor
! Short wordlength transfor
! nhanceents of ro)'stness and fle%i)ilit$for o#eration over a variet$ of networ(s
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Structure of H.264 Video Encoder
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etwor( A)straction 9a$er
• Facilitates the ability to map H.264 V! data
to transport layers such as "#$%&$' H.(2)'
*$E+,2.
+ A9 :nits
+ VC9 and nonVC9 'nits
+ 3araeter sets
+ Access 'nits
+ Coded video se;'ence
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A9* 3araeter Sets
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VC9* 5evol'tion or vol'tion<
! There is no single coding eleent in the VC9 that#rovides the a=orit$ of the significant i#roveent
in co#ression efficienc$ in relation to #rior video
coding standards.
! -t is rather a #l'ralit$ of smaller improvements thatadd '# to the significant gain.
! The )asic so'rcecoding algorith is a h$)rid of
inter-picture prediction to e%#loit te#oral
statistical de#endencies and transform coding ofthe #rediction resid'al to e%#loit s#atial statistical
de#endencies.
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VC9* leents
! 3ict'res> 1raes> 1ields
! 0acro)loc(s ?0,s@?6%6@
! Slices> Slices Gro'#s
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VC9* Coding the Slices
! ach slice can )e coded 'sing different coding
t$#es as follows* + I slice: A slice in which all acro)loc(s of the slice are coded 'sing intra
#rediction.
+ P slice: -n addition to the coding t$#es of the - slice> soe acro)loc(s
of the 3 slice can also )e coded 'sing inter #rediction with at ost one
otionco#ensated #rediction signal #er #rediction )loc(.
+ B slice: -n addition to the coding t$#es availa)le in a 3 slice> soe
acro)loc(s of the , slice can also )e coded
+ SP slice ?switching 3 slice@* coded s'ch that efficient switching )etweendifferent #recoded #ict'res )ecoes #ossi)le.
+ SI slice ?switching - slice@* allows an e%act atch of a acro)loc( in an
S3 slice for rando access and error recover$ #'r#oses.
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3ee( into ncoder
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Ada#tive 1rae/1ield Coding
! B choices*
+ To co)ine the two fields together and to code the
as one single coded frae ?frame mode@.
+ To not co)ine the two fields and to code the asse#arate coded fields ?field mode@.
+ To co)ine the two fields together and co#ress
the as a single frae> )'t when coding the frae to
s#lit the #airs of two verticall$ ad=acent acro)loc(sinto either #airs of two field acro)loc(s or frae
acro)loc(s )efore coding the.
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Ada#tive 1rae/1ield Coding
! 3A11 ?3ict'reAda#tive 1rae/1ield@
+ The choice )etween first 2
+ 6D )etter than field onl$ in general
! 0,A11 ?0acro,loc(Ada#tive 1rae/1ield @
+ onoving* frae ode> oving* field ode
+ :se a #air of 0,s ?6%B2 l'a@
+ 4D )etter than 3A11 in general
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-ntra1rae 3rediction
Constrained intra coding ode* #rediction onl$ fro intracodedneigh)oring 0,s
B odes* -ntraE4%4> -ntraE6%6 ?with chroa#rediction@ and -E3C0
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-nter1rae 3rediction
! 1'll sa#le> half sa#le> one;'artersa#le + Half* a##l$ onediensional 6ta# 1-5 filter
+ One;'arter* average f'll and half
! 5es'lts* + Acc'rate otion re#resentation
+ 0ore fle%i)ilit$ in #rediction filtering
! "ifferent degrees of low #ass filtering co'ld )echosen
! )etter #reserving hifre;'enc$ content.
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Transfor> Scaling and 7'antiation
! 4%4 -nteger transfor vs. F%F "CT + o isatch in inverse transfor
+ 9ess co#'tations> short #rocessing wordlength
+ 9ess noise
!2 ;'antiation val'es ste# sie* 2D! one ste# eans 2D )it rate change
! 6 ste#s* factor of 2
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ntro#$ Coding
! CAV9C ?Conte%tAda#tive Varia)le 9engthCoding@ + V9C ta)les for vario's s$nta% eleents are switched de#ending
on alread$ transitted s$nta% eleents. + Since the V9C ta)les are designed to atch the corres#onding
conditioned statistics> #erforance is i#roved in co#arison toschees 'sing a single V9C ta)le.
! CA,AC ?Conte%tAda#tive ,inar$ AritheticCoding@ + allows the assignent of a noninteger n')er of )its to each
s$)ol of an al#ha)et + #erits ada#tation to nonstationar$ s$)ol statistics + 'ses onl$ shifts and ta)le loo('#s + Co#ared to CAV9C> t$#icall$ #rovides a red'ction in )it rate
D+D
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-n9oo# "e)loc(ing 1ilter
• +oal- reduce blockiness and maintain sharpness
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3rofiles and 9evels
! 3rofiles* 1acilitate intero#era)ilit$ )etweenvario's a##lications. + "efines a set of coding tools or algoriths that can )e 'sed in
generating a conforing )itstrea
+ -ncl. ,aseline> 0ain> %tended> High?4@
! 9evels* #lace constraints on certain (e$#araeters of the )itstrea + Corres#ond to #rocessing #ower and eor$ ca#a)ilit$ of a
codec + Set lits for data )itrate> fraesie> #ic )'ffer sie. g. 7C-1>
-T:56I> H"TV etc.
+ :niversal ?@ 'sed in different #rofile
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3rofiles* Coding 1eat'res
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Co#'tation Cons'#tion
! :se large ao'nt of co#'tation to achievehigh ;'alit$> relia)ilit$ and co#ression ratio + -ntra/inter frae #rediction* J6ID + -nteger transfor* JID + rror resilience* J2ID
+ "e)loc(ing filter* JID! ncoding* JI% of 03G2Ks C3: 'sage! 1or c'rrent hoe 3C 'sers> realtie software
decoding ?H"TV ;'alit$@ co'ld )e achieved>
)'t not encoding! 5ecoend software*
+ 7'ic(Tie Alternative ?www.freecodecs.co@ + L264 ?www.videolan.org/%264.htl@
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9icensing
! Standard* no free l'nch
! 9essons fro 03G4 Vis'al
+ 8as not friendl$ at the )eginningM
! H.264
+ Codec an'fact'res #a$ for the cons'er
'se )$/)etween end 'sers
+ Chea# for free television #rovider
+ 1ree internet )roadcast till 2II.2.B
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A##lications
! H" "V" Video ?"V"1or'@ ,l'ra$ "is(?,"A@ ?High 3rofiles* andator$@
! "V, in 'ro#e> "0, in Norea> -S",T in
a#an! "irect )roadcast satellite TV ?'ltiregion@
! BG33 ?o#tional feat're@
! -T1* 51CBPF4 for 5T3! -T:T* H.B2% ?in #rod'ction@
! Vo"
