Post on 19-Dec-2015
Overview of the H.264/AVC Video Coding Standard
T. Wiegand, G.J. Sullivan, G. Bjøntegaard and A. Luthra, IEEE Transaction on Circuits and Systems for Video Technology, Vol. 13, no. 7, Jul. 2003.
Presented by Peter
H.264/AVC
Latest Video coding standard Basic design architecture similar to MPEG-x
or H.26x Better compression efficiency
Up to 50% in bit rate savings Subjective quality is better Advance functional element
History of H.264/AVC
Initiate by the Video Coding Experts Group (VCEG) in early 1998
Previous name H.26L Target to double the coding efficiency First draft was adopted in Oct. of 1999 In Dec. of 2001, VCEF and the Moving Pictures
Experts Group (MPEG) formed a Joint Video Team (JVT)
Approved by the ITU-T as H.264 and ISO/IEC as International Standard 14496-10 (MPEG-4 part 10) Advanced Video Codec (AVC) in Mar. 2003
Design Features Highlights
Features for enhancement of prediction Directional spatial prediction for intra coding Variable block-size motion compensation with small block
size Quarter-sample-accurate motion compensation Motion vectors over picture boundaries Multiple reference picture motion compensation Decoupling of referencing order form display order Decoupling of picture representation methods from picture
referencing capability Weighted prediction Improved “skipped” and “direct” motion inference In-the-loop deblocking filtering
Design Features Highlights
Features for improved coding efficiency Small block-size transform Exact-match inverse transform Short word-length transform Hierarchical block transform Arithmetic entropy coding Context-adaptive entropy coding
Design Features Highlights
Features for robustness to data errors/losses Parameter set structure NAL unit syntax structure Flexible slice size Flexible macroblock ordering (FMO) Arbitrary slice ordering (ASO) Redundant pictures Data Partitioning SP/SI synchronization/switching pictures
Directional spatial prediction for intra coding Intra prediction is to predict the texture in current block using
the pixel samples from neighboring blocks Intra prediction for 44 and 16 16 blocks are supported in
H.264
Figs. from [2]
Variable block-size motion compensation with small block size Partitioned in 2 stages In the 1st stage, determine first 4
modes 1616, 168, 816, 88
If mode 4 (88) is chosen, further partition into smaller blocks for every 88 block 84, 48, 44
At most 16 motion vectors may be transmitted for a 1616 macroblock
Large computational complexity to determine the modes
Fig. from [3]
Multiple reference picture motion compensation – P Slices More than one prior coded
picture can be used as reference
for MC prediction Reference index parameter is
transmitted for each MC 1616, 168, 816 or 88
For smaller blocks within the 88 use 1 reference index
P macroblock can also be coded in P-Skip type
Fig. from [1]
Multiple reference picture motion compensation – B Slices Utilize two distinct lists of reference pictures Four different types of inter-picture predict
List 0, list 1, bi-predictive, and direct prediction Bi-predictive
weighted average of MC list 0 and list 1 Direct prediction
Inferred from previously transmitted syntax Either list 0 or list 1 prediction or bi-predictive
Similar macroblock partitioning as P slices is utilized B_Skip mode is supported
Small block-size transform
Transformation is applied on 44 blocks Close to 44 DCT transform Inverse-transform mismatches are avoided The transform matrix is given as
Short word-length transform
Post-scaling matrix in forward transform Pre-scaling matrix in inverse transform Only integer operations and shifting are needed in transformation and
quantization
Hierarchical block transform
For macroblock is coded in 1616 Intra mode and chrominance blocks
DC coefficients are further grouped and transformed
Hadamard transform is used for chrominance block
Intended for coding of smooth areas
Figs. from [4]
Profiles
3 profiles - Baseline, Main and Extended Profile
15 levels Picture size: up to 250M pixels/s Bit Rate: up to 240M bps
Potential Applications
Baseline (low latency) H.320 conversational video services 3GPP conversational H.324/M services H.323 with IP/RTP 3GPP using IP/RTP and SIP 3GPP streaming using IP/RTP and RTSP
Main (moderate latency) Modified H.222.0/MPEG-2 Broadcast via satellite, cable, terrestrial or DSL DVD and VOD
Extended Streaming over wired Internet
Any (no requirement on latency) 3GPP MMS Video mail
References
1. T. Wiegand, G.J. Sullivan, G. Bjøntegaard and A. Luthra, “Overview of the H.264/AVC Video Coding Standard,” IEEE Transaction on Circuits and Systems for Video Technology, Vol. 13, no. 7, Jul. 2003.
2. I.E.G. Richardson, “H.264/MPEG4 Part 10: Intra Prediction,” available at http://www.vcodex.com
3. I.E.G. Richardson, “H.264/MPEG4 Part 10: Inter Prediction,” available at http://www.vcodex.com
4. I.E.G. Richardson, “H.264/MPEG4 Part 10: Transform and Quantization,” available at http://www.vcodex.com