Video Coding Concept

1
Video Coding Concept

• Kai-Chao Yang

2
Video Sequence and Picture

• Video sequence
• Large amount of temporal redundancy
• Intra Picture/VOP/Slice (I-Picture) (p.295)
• Encoded without referencing others
• All MBs are intra coded
• Inter Picture/VOP/Slice (P-Picture, B-Picture)
  (p.295)
• Encoded by referencing other pictures
• Some MBs are intra coded, and some are inter coded

Intra 0
Inter 1
Inter 2
Inter 3
Inter 4
Inter 5
3
Group of Pictures
GOP
GOP
GOP

• Group of Pictures (GOP) (p.295, p.455-457)
• GOP in H.264/AVC
• Multiple reference frames
• B-pictures can be referenced
• Variable number of B-pictures
• GOP in Scalable Video Coding (SVC) of H.264/AVC
• Hierarchical prediction structure

I
B
B
P
B
B
P

B
B
I
B
B
P

Video stream
Frame order
0
1
2
3
4
5
6
Encoding order
0
2
3
1
5
6
4
4
Picture, Slice, MacroBlock, and Block
8
8

• H.264/AVC
• Variable MB size
• 4x4 transform block

block
8
MB
8
Slice
Picture
5
Flow Chart of Video Coding

• (p.293-295)

Low frequency
High frequency
(lossy compression)
(lossless compression)
(spatial ? frequency)
MB
Transform
Quantization
Entropy Coding
-
Decoder
Motion Compensation
Quantization-1
(removing temporal redundancy)
Inverse Transform

Motion Estimation
(frame reconstruction)
Reference frame
Current frame
(estimating similar blocks)
6
Coding of I-Slice

• Example

DCT
Original block
Transformed block
Quantization matrix
Bit-stream
15 0 -2 -1 -1 -1 0
Zig-zag scan
Entropy coding
7
Coding of P-Slice

• Example

Motion Compensation

-
Residual
Original current frame

Motion Vectors

Motion Estimation
Frame buffer
Reconstructed reference frame
8
Structure of H.264/AVC Encoder
Representation of video content
Formats of VCL representation
9
H.264/AVC Flow Chart
10
New Features of H.264/AVC

• Multiple reference frames
• Variable block size
• 1/4 and 1/8 motion vector precision
• Weighted prediction
• 4x4 transform block
• Intra prediction
• De-blocking filter
• CABAC CAVLC

11
FMO and ASO

• Examples of Flexible MB Order (FMO)
• Arbitrary Slice Order (ASO)
• sending and receiving the slices of the picture
  in any order relative to each other

12
H.264/AVC Profiles
13
H.264/AVC FRExt Amendment

• Completed in July 2004
• For coding of high-fidelity video material
• Professional film production, video post
  production, or high-definition TV/DVD
• Higher quality, higher rates
• Professional extensions ? Fidelity Range
  extensions (FRExt)

http//plusd.itmedia.co.jp/lifestyle/articles/0407
/09/news074.html
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Profiles of H.264/AVC FRExt

• High profiles
• High profile (HP)
• Supporting 8-bit with 420 sampling
• High 10 profile (Hi10P)
• Supporting 10-bit with 420 sampling
• High 422 profile (H422P)
• Supporting 10-bit with 422 sampling
• High 444 profile (H444P)
• Supporting 12-bit with 444 sampling, and
  efficient lossless coding and an integer residual
  color transform for coding RGB video

15
References

• T. Wiegand, G.J. Sullivan, G. Bjntegaard, and A.
  Luthra, Overview of the H. 264/AVC video coding
  standard, in IEEE Transaction on Circuits and
  Systems for Video Technology, 2003.
• Iain E. G. Richardson, H.264 and MPEG-4 Video
  Compression Video Coding for Next-generation
  Multimedia, Wiley, 2003.
•  G. J. Sullivan, P. Topiwala, and A. Luthra, The
  H.264/AVC Advanced Video Coding Standard
  Overview and Introduction to the Fidelity Range
  Extensions, in SPIE Conference on Applications
  of Digital Image Processing, 2004.