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How Efficient is HEVC?
! P8 H) l4 g6 G O) tThe new High Efficiency Video Coding (HEVC) / H.265 standard is expected to be more efficient than its predecessor, H.264 Advanced Video Coding. Just how much better it will perform is a crucial question. Will it be enough of an improvement to justify widespread industry adoption of the new standard?# I1 x9 L V* a$ k& [
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Bin Li, Gary Sullivan and Jizheng Xu published a performance comparison between H.264/AVC and Working Draft 4 of HEVC in November 2011. You can find the full document and results here:$ R. ^& [' ]; Y- J. m* r
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Document JCTVC-G399$ K" D7 Z# H+ r1 n
. O' o+ T9 \+ x! q; JTable 4 of the document compares the compression performance of the HEVC test model ("HM") and the H.264 test model ("JM"). On average, HEVC out-performs H.264 by 39% for random access scenarios (e.g. broadcast) and by 44% for low delay scenarios (e.g. video calling).
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4 _4 V4 n4 U$ r( M. v0 G2 ^This means that the HEVC codec can achieve the same quality as H.264 with a bitrate saving of around 39-44%.
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# z# y* o6 j. m1 nHEVC is still under development and we might expect to see a further increase in performance from future versions of the draft standard.+ c$ T/ m1 D4 C3 d, b# L: w* c
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+ b# \0 h+ g7 y5 cHigh Efficiency Video Coding
, h3 n% k, ~9 t8 M" F6 WHigh Efficiency Video Coding (HEVC) is a new Standard under development by the ISO and ITU-T. The Moving Picture Experts Group (MPEG) and Video Coding Experts Group (VCEG) have set up a Joint Collaborative Team on Video Coding (JCT-VC) with the aim of getting the new standard ready for publication in 2012/2013. It's likely to be published jointly as a new MPEG standard and a new ITU-T standard, possibly H.265./ H- E. H$ b* B1 X8 C5 |' G ~0 ]
The HEVC Test Model1 O9 g W8 `$ J* J; q) S/ C, H
Following the JCT-VC and MPEG meeting in October 2010, a Test Model for HEVC, HM1, was specified. The Test Model defines two broad categories of video coding tools, for (a) High Efficiency and (b) Low Complexity applications.0 K( Y/ K4 a4 K% w- q) _
. _+ ` D6 p& c0 xWhat's in the Test Model?
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4 c1 k8 B3 ]- `2 L0 I) BThe main components are as follows:8 L+ c' s# ~, V8 ]% @
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Coding unit: Block sizes from 8x8 to 64x64 in tree structure
) [+ j' x5 C1 ?Transform: Quadtree structured block size from 4x4 to 32x32 samples3 ?! ^0 ^. U+ a0 e; ^! h
Intra prediction: Up to 34 intra prediction directions9 E/ _7 O; L: N& {% Y) `0 @, n9 {2 I1 d
Interpolation: 6- or 12-tap interpolation filter, down to 1/4-sample' P. F3 |+ X: ~2 S4 L9 q/ L
Motion prediction: Advanced motion vector prediction
* Z4 D, P& S6 i" mEntropy coding: CABAC or Low Complexity Entropy Coding (LCEC)
% j& v% E P8 {9 V+ HLoop filter: Deblocking filter or Adaptive Loop Filter (ALF)$ d* C0 I" O$ ?$ q3 S+ `2 B
Precision: Extended precision options. W# X3 e' p! G
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Many coding tools have been scheduled for further investigation and may be incorporated into the Test Model if they offer suitable compression gains.3 e3 e4 D y8 c9 Z9 ^0 Z: i
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How will it compare to H.264/AVC?9 ?! B k! I( g8 X: Q
/ X4 V' J# \7 I& Z$ PCurrent indications are that the new standard could provide 2x better video compression performance (i.e. around half the bitrate for a similar quality level) at the expense of significantly higher computational complexity, compared with H.264/AVC.! Y0 n/ e3 h9 K8 e( i' k% V" a
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When will it be finished?
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The timescale for completing the HEVC standard is as follows: 1 X6 o' Z- u) e* }& B- C5 P
February 2012: Committee Draft (complete draft of standard)9 m5 x5 f' c. O0 A4 m1 }
July 2012: Draft International Standard+ U& d" F- {) n9 J- L
January 2013: Final Draft International Standard (ready to be ratified as a Standard)
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Where can I find out more?
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! r+ _2 m$ T" e3 t% s2 x4 VJCT-VC Meeting Documents : download JCTVC-C405 for a summary of the HEVC test model HM1.
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$ [6 @0 k3 V7 B' P L( b# \5 uNovember 20104 q0 v* e# r5 M* C, m
The Joint Collaborative Team
# H: N: x9 X. RFrom the ITU website:1 V; E' Y# x6 q0 `! e* } y
8 T a% Q, O' e# \7 K"The Joint Collaborative Team on Video Coding is a group of video coding experts from ITU-T Study Group 16 (VCEG) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG) created to develop a new generation video coding standard that will further reduce by 50% the data rate needed for high quality video coding, as compared to the current state-of-the-art AVC standard (ITU-T Rec. H.264 | ISO/IEC 14496-10). This new coding standardization initiative is being referred to as High Efficiency Video Coding (HEVC)."! _4 S( W8 J5 O6 o
# e( R+ ~- Z9 h3 ATo find out more:
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Joint Collaborative Team on Video Coding |
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