High Efficiency Video Coding

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How Efficient is HEVC?
- Z( @/ b* Y5 I/ K1 Y, S8 gThe 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?

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:
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/ K: q0 k) C7 F7 S+ IDocument JCTVC-G399
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' x+ m/ U% A7 m/ I1 `( O3 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).

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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* y8 d7 |1 S9 J# g$ DHEVC is still under development and we might expect to see a further increase in performance from future versions of the draft standard.


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. C( a$ k1 X+ R$ O- T' H( W( VHigh Efficiency Video Coding
& P$ s, w. t1 U! o' lHigh 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.
1 J: O/ ?2 b8 a2 n8 t- KThe HEVC Test Model
% Z& q' H5 Y' O9 a5 l+ \+ W0 f% g* vFollowing 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.

What's in the Test Model?

The main components are as follows:

Coding unit: Block sizes from 8x8 to 64x64 in tree structure
. l& s; `$ K$ i9 Z: D1 F" JTransform: Quadtree structured block size from 4x4 to 32x32 samples
/ v8 s% g3 g: ]Intra prediction: Up to 34 intra prediction directions
  j+ a, T+ b; ?7 F. {Interpolation: 6- or 12-tap interpolation filter, down to 1/4-sample
( c. M( w5 a' J4 a- J; D, u! k8 LMotion prediction: Advanced motion vector prediction
Entropy coding: CABAC or Low Complexity Entropy Coding (LCEC)
* S( L2 L0 B, `: x2 `1 m+ QLoop filter: Deblocking filter or Adaptive Loop Filter (ALF)
Precision: Extended precision options

) ^4 ~2 ~2 A( c( r0 gMany coding tools have been scheduled for further investigation and may be incorporated into the Test Model if they offer suitable compression gains.

How will it compare to H.264/AVC?

" s+ X! D' _2 c8 \7 t7 ^Current 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.

* o/ a5 d2 ^/ J% oWhen will it be finished?

The timescale for completing the HEVC standard is as follows:
. r' O* d& E3 N4 N5 F( P' SFebruary 2012: Committee Draft (complete draft of standard)
July 2012: Draft International Standard
8 n; Y$ b, \$ X3 h6 J) j0 N. F) I; YJanuary 2013: Final Draft International Standard (ready to be ratified as a Standard)

Where can I find out more?
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JCT-VC Meeting Documents : download JCTVC-C405 for a summary of the HEVC test model HM1.
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November 2010
  The Joint Collaborative Team
From the ITU website:

& I# M, F( j  o$ {# T"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)."

8 G  {, y' D* C$ A0 V1 l0 `To find out more:

Joint Collaborative Team on Video Coding