Audio Video coding Standard of AVS China

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Audio Video coding Standard of (AVS) China

• Submitted by,
• Swaminathan Sridhar
• EE 5359 Multimedia Processing Project

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Video coding standards 5
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Video coding standards 4, 5

• MPEG-2 (DVD, MPEG-2 (DVD, SDTV, HDTV)
• More than 10 years old
• Compression efficiency
• 4.7GB DVD 2 hours movie (5.3Mbps)
• 18GB 2 hours high definition movie (20Mbps)
• MPEG-4 AVC/H.264 (Multimedia applications)
• Advanced coding techniques
• Multiple-reference frame prediction
• Context-based adaptive binary arithmetic coding
• High compression efficiency
• 1.52Mbps for SD, 68Mbps for HD
• Save storage space, channel bandwidth, and
  frequency spectrum

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Development stages of AVS 3

• December 2003
• In the 7th AVS meeting, AVS-video (part-2) and
  AVS-system (part-1) was finalized.
• December 2004
• In the 11th AVS meeting, AVS-M (part-7) was
  finalized
• March 2005
• Authentication of AVS101 high definition
  decoding chip
• May 2005
• AVS Industry Alliance was set up.
• June 2005
• Joint AVS/ISMA workshop on IPTV standard and
  industry forum
• February 2006
• AVS part-2 was announced as a national standard.

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Parts of AVS 3
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Applications of the commonly used parts of AVS
China 3

• AVS Part-2 HD/SD video
• Jizhun Profile Zengqiang Profile
• HD broadcasting
• High density storage media
• Video surveillances
• Video on demand
• AVS Part-7 Mobility video
• Jiben Profile
• Record and local playback on mobile devices
• Multimedia Message Service (MMS)
• Streaming and broadcasting
• Real-time video conversation

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Major and Minor coding tools used in AVS part 2
1

• Major tools
• Interlace handling Picture-level adaptive
  frame/field coding (PAFF)
• Macroblock-level adaptive frame/field coding
  (MBAFF)
• Intra prediction 5 modes for luma and 4 modes
  for chroma
• Motion compensation 16x16/16x8/8x16/8x8 block
  size
• Resolution of MV 1/4-pel, 4-tap interpolation
  filter
• Transform 16bit-implemented 8x8 integer cosine
  transform
• Quantization and scaling scaling only in encoder
• Entropy coding 2D-VLC and Arithmetic Coding
• In-loop deblocking filter
• Minor tools
• Motion vector prediction
• Adaptive scan

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AVS encoder structure 1
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Different picture types 2

• Three types of picture are defined by AVS namely
• Intra pictures (I)
• Predicted pictures (P)- At most two reference
  frames (P or I)
• Interpolated pictures (B)- two reference frames
  (I or P or both)

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MB level Adaptive frame coding 2

• MB-level adaptive frame/field coding (MBAFF)
• The frame/field encoding decision is made
  independently for each vertical pair of macro
  blocks in a frame.
• A frame consisting of both moving and non-moving
  regions is coded more efficiently by
• frame mode for the non-moving regions
• field mode for the moving regions
• MBAFF is much more complicated than PAFF
• zig-zag scanning
• motion vector prediction
• intra prediction
• deblocking
• context modeling in entropy coding
• The advantage compared with the MBAFF in H.264
• A field-coded MB belonging to the bottom field
  CAN use the top field of
• the same frame as a reference for motion
  prediction

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Intra Prediction 2

• Five different modes for luma is as shown below

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Luma Intra Prediction difference between AVS and
H.264 6

• AVS
• Block size 8x8
• 5 modes
• Reference pixels low pass filtered
• Advantages low complexity with less modes
• H.264
• Block size 4x4 or 16x16
• 9 modes for 4x4 and 4 modes for 16x16
• Advantage better prediction
• Disadvantage more complex

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Intra prediction modes for Chroma 2

• 4 Prediction modes for Chroma

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Inter Prediction and Motion Compensation 1

• At most 2 frames can be stored as reference for
  motion prediction.
• Block size of motion prediction and compensation
• 16x16, 16x8, 8x16 and 8x8
• In each MB, the number of MV pairs can be 1, 2 or
  4, depending on the block size of MC.
• MVD, the difference between the predicted MV and
  the real MV, is coded.
• Resolution of MV
• 1/4-pixel for luma
• 1/8-pixel for chroma
• Motion prediction modes
• Forward
• Backward (only applicable for B frame)
• Bi-directional (only applicable for B frame)
• Skip
• Direct
• Symmetric

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Reference Frame 1

• At most 2 reference frames are used. No matter
• PAFF or MBAFF is used,
• if the current MB is frame-coded, 2 frames can
  be used as reference for motion prediction.
• if the current MB is field-coded, 4 fields can
  be used.
• Reference index should be coded with every MC
  block to indicate which reference picture is used

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Reference Index 1
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Motion Vector Prediction 3
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Motion Vector Prediction 3

• Use A, B, C, Ds MV (MVA, MVB, MVC and MVD) to
  predict Es MV (PredMVE)
• Reason reduce the bits for coding MV
• Method
• Geometrical median of MVA, MVB, MVC
• VAB Dist(MVA, MVB)
• VBC Dist(MVB, MVC)
• VCA Dist(MVC, MVA)
• FMV Median(VAB, VBC, VCA) where Dist(MV1,
  MV2)x1-x2y1-y2.
• Determine PredMVE
• If FMV equals VAB, PredMVEMVC.
• If FMV equals VBC, PredMVEMVA.
• If FMV equals VCA, PredMVEMVB.

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Interpolation for Luma 3

• Resolution
• Quarter-pixel
• Filter
• Half-pixel
• Blue -1, 5, 5, -1
• Quarter-pixel
• White 1, 7, 7, 1
• Red bilinear

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Interpolation for Luma 3
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Interpolation for Chroma 3
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Interpolation for Chroma 3

• Bilinear
• predMatrixx,y (8dx)(8dy)A dx(8dy)B
  (8dx)dyC dxdyD/64

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Forward and Backward Prediction 1

• Forward prediction
• MV pointing only to the previous frame
• Get reference block only from the previous frame
• Backward prediction
• MV pointing only to the backward frame
• Get reference block only from the backward frame

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Forward and Backward Prediction 1
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Bi-directional Prediction 1

• Skip mode
• Block size of MC 16x16
• No transform coefficient is coded, since they all
  equal zeros.
• No MV is coded, since they can be calculated.
• Direct mode
• Block size of MC 16x16 or 8x8
• Transform coefficients are not all zeros, so they
  had to be coded.
• No MV is coded, since they can be calculated the
  same way for skip mode.
• Symmetric mode
• Block size of MC 16x16, 16x8, 8x16, 8x8.
• Transform coefficients are not all zeros, so they
  had to be coded.
• Only forward MV is coded, and the backward MV can
  be calculated by using the forward one.

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MV Derivation for Skip and Direct Mode 1
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MV Derivation for Symmetric Mode 1
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Pre-scale Transform 3
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AVS 88 ICT Matrix 3
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Context-based Adaptive 2D VariableLength Coding
(CA-2D-VLC) 1

• (level, run) pair mapping to CodeNum using VLC
  tables
• levelgt0 CodeNum is the number in VLC tables
  directly
• levellt0 CodeNum is number1 in VLC tables .
• Example
• level 2, run1, CodeNum11
• level -2, run1, CodeNum12
• CodeNum mapping to bit
• string using Exp-Colomb coding

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Context-based Adaptive 2D VariableLength Coding
(CA-2D-VLC) 1
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Deblocking Filter 3

• 8x8 block
• Three steps
• Choose boundary strength
• (BS), according to
• Prediction modes
• MV
• Decide whether to filter
• according to
• Quantization Parameter (QP)
• BS
• Apply filter to the boundary

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Deblocking Filter 3
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AVS Part-2 vs H.264/AVC 4, 6
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AVS Part-2 vs H.264/AVC 4, 6
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AVS Part-2 performance 1, A
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Container.qcif sequence A
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Decoded frame A
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Claire.qcif sequence A
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Decoded frame A
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News.qcif sequence A
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Decoded frame A
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References 1 L. Yu et al. An Overview of
AVS-Video tools, performance and complexity,
Visual Communications and Image Processing 2005,
Proc. of SPIE, vol. 5960, pp.596021, July 31,
2006. 2 L. Yu et al. An area-efficient VLSI
architecture for AVS intra frame encoder Visual
Communications and Image Processing 2007, Proc.
of SPIE-IS T Electronic Imaging, SPIE vol.
6508, pp. 650822, Jan. 29, 2007. 3 W. Gao et
al. AVS - The Chinese Next-Generation Video
Coding Standard NAB, Las Vegas, 2004. 4 T.
Wiegand et al. Overview of the H.264/AVC Coding
Standard IEEE Trans. Circuits Syst. Video
Technol., vol.13, pp.560-576, July 2003. 5 J.
Wang et al. An AVS-to-MPEG2 Transcoding System
China Proceedings of 2004 International Symposium
on Intelligent Multimedia, Video and Speech
Processing , Hong Kong, pp. 302-305, October
20-22, 2004. 6 X. Wang et.al Performance
comparison of AVS and H.264/AVC video coding
standards J. Comput. Sci. Technol., Vol.21,
No.3, pp.310-314 J, May 2006. 7 Bo Tang et al.
AVS Encoder Performance and Complexity Analysis
Based on Mobile Video Communication, WRI
International conference on Communications and
Mobile Computing, CMC 09, volume 3, pp.
102-107, 6-8 Jan. 2009.
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Web References AVS China software A
ftp//159.226.42.57/public/avs_doc/avs_software