|
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?' o$ A W/ e/ @4 {2 i' P+ w
% r! F+ C. F" m( N( @6 E/ _
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:
% ^& L4 x) t2 v( j
/ K: q0 k) C7 F7 S+ IDocument JCTVC-G399
7 X+ v1 c* A; ]% N: @1 }
' 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).+ o7 S" f9 W$ Z( y8 m; f- t
; a6 l7 B% Y# ^# o
This means that the HEVC codec can achieve the same quality as H.264 with a bitrate saving of around 39-44%.
( |; n7 b/ j" f, Z4 b7 z; g
* 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.0 b. p. G8 r: k6 d& D# I, W
1 d1 d& Y8 A& Z* `" P' T
7 v! u/ z" G6 N: L; u/ F
" p4 L8 ~; e# u6 k& m8 [/ w ' j5 i7 I! `- m* g5 ]; S
. 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.$ | B9 ~ T3 ?1 u" B) g% Q$ F
- S0 s& _$ U& `% ?( f
What's in the Test Model? 0 H4 g: C8 D+ j( N- H0 w" w
3 V( s, ? p. h! c
The main components are as follows:0 c" H5 [6 G" C2 K
& j6 d/ ^ }! Z Y: s$ [0 z. Q3 b3 k
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 / a8 E. X5 o$ S' M7 V
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)- p0 A" S) l3 z6 x: x
Precision: Extended precision options" t& X% n& S- i9 p, b0 y) x- |
) ^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., P4 q0 m. i+ C/ O L
9 ?3 k- v' V2 v3 c! O
How will it compare to H.264/AVC?0 d4 A0 A7 T" B6 r" m3 C9 A( ~% X" r
" 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./ q! Y. O# j( W% \* O8 U& D( t/ ] m7 I
* o/ a5 d2 ^/ J% oWhen will it be finished?/ a( b! k- @# K* s2 @+ Q: m
3 t& V- u4 s0 S; e- L3 f/ W$ q
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)* D9 O- w) C: S
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)9 L' y' i5 X' M1 \2 u- L
1 T& l- g* t# ` L% J# {5 v" g v
Where can I find out more?
$ E8 e t& p- J* D+ A1 u5 L# I0 g) b ^. `: r, [
JCT-VC Meeting Documents : download JCTVC-C405 for a summary of the HEVC test model HM1.
l* W: i' o- O5 q: ~" y6 m4 R2 x9 U7 p. R. M' }4 @
November 20101 }1 M& R9 [4 U/ ?
The Joint Collaborative Team0 j' K- k& I6 Q& I! Y
From the ITU website:/ |7 g" Q" X" j3 q
& 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)."2 t8 g- {: i! j/ L/ Z+ A
8 G {, y' D* C$ A0 V1 l0 `To find out more:. |+ k8 p7 t4 H8 g* B) J
, g% I3 P: a. i$ i5 b* r' ]
Joint Collaborative Team on Video Coding |
|