28 h 264-avc_by_dhchang

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MPEG 4, H.264 Compression StandardsMPEG 4, H.264 Compression Standards

Presented by Dukhyun Chang([email protected])

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ContentsContents

IntroductionFeatures of the H.264/AVCProfile & performance of H.264/AVC Conclusion

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Evolution of Video coding Evolution of Video coding StandardsStandards

ITU-TStandard

JointITU-T/MPEG

Standards

MPEGStandard

1988 1990 1992 1994 1996 1998 2000 2002 2004

H.261(Version 1)

H.261(Version 2)

H.263 H.263+ H.263++

H.262/MPEG-2 H.264/MPEG-4 AVC

MPEG-1MPEG-4

(Version 1)MPEG-4

(Version 2)

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Structure of H.264/AVC video encoderStructure of H.264/AVC video encoder

Control Data

Video Coding Layer

Data Partitioning

Network Abstraction Layer

H.323/IP MPEG-2 etc.H.320 MP4FF

Coded Macroblock

Coded Slice/Partition

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ApplicationsApplications

Broadcast

Streaming

Content Server

InternetLink

Mobile Communication

Storage

DMB Multimedia Service

VCL

NAL

Mpeg-2 systems

RTP payload

ISO media file format

encapsulation

H.320, H.324/M

NAL gives VCL network independent interface

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Data Structure of MPEGData Structure of MPEG

GOP GOP GOPSH SH SH

I B B P B B P …… BBB P

slice

slice

MB MB MB MB MB MB ….

Y1

Y3

Y2

Y4Cb Cr

Sequence

GOP

Picture

Slice

Macroblock

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ContentsContents

IntroductionFeatures of the H.264/AVCProfile & Performance of H.264/AVCConclusion

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Basic coding structure of H.264/AVC for a macroblBasic coding structure of H.264/AVC for a macroblockock

EntropyCoding

Scaling & Inv. Transform

Motion-Compensation

ControlData

Quant.Transf. coeffs

MotionData

Intra/Inter

CoderControl

Decoder

MotionEstimation

Transform/Scal./Quant.-

InputVideoSignal

Split intoMacroblocks16x16 pixels

Intra-frame Prediction

De-blockingFilter

OutputVideoSignal

New features of H.264

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TransformTransform

MPEG-4 AVC

MPEG-2 / MPEG-4

Integer Transform

Incoming 4x4 Block

transformed4x4 Block

DCT Transform

Incoming 8x8 Block

transformed8x8 Block

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Intra & Inter Coding StructureIntra & Inter Coding Structure

Intra Coding Structure– Intra Frame Motion estimation cannot be exploited

• Eliminate spatial redundancy

– Directional spatial prediction

Motion Compensation– Various block sizes and shapes for motion compensation

• More precise compensation

0

Sub-macroblock partitions

0

1 0 1

0 1

2 3

0 0

1 0 1

0

2

1

3

1 macroblock partition of 16*16 luma samples and

associated chroma samples

Macroblock partitions

2 macroblock partitions of 16*8 luma samples and

associated chroma samples

4 sub-macroblocks of 8*8 luma samples and

associated chroma samples

2 macroblock partitions of 8*16 luma samples and

associated chroma samples

1 sub-macroblock partition of 8*8 luma samples and

associated chroma samples

2 sub-macroblock partitions of 8*4 luma samples and

associated chroma samples

4 sub-macroblock partitions of 4*4 luma samples and

associated chroma samples

2 sub-macroblock partitions of 4*8 luma samples and

associated chroma samples

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Motion CompensationMotion Compensation

Multiple reference pictures– Arbitrary weights– Regardless of the temporal direction– Can use B-Slice as reference

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Adaptive Deblocking FilterAdaptive Deblocking Filter

Deblocking Filter– There are severe blocking artifacts

• 4*4 transforms and block-based motion compensation– Result in bit rate savings of around 6~9%– Improve subjective quality and PSNR of the decoded picture

Without Filter With AVC Deblocking Filter

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FMO (1/2)FMO (1/2)

FMO (Flexible Macroblock Ordering)

– Slice (composed in FMO) Enhance Robustness to data loss

Picture

Slice Group Slice

….

.….

Independently-decodable

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FMO (2/2)FMO (2/2)

Slice #0

Slice #1

Slice #2

Subdivision of a picture into slices when not using FMO

Slice Group #0

Slice Group #1

Slice Group #2

Subdivision of a QCIF frame into slices when utilizing FMO

Slice Group #0Slice Group #1

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ASOASO

ASO (Arbitrary Slice Ordering)– Independently-decoded Slice

• Enables sending and receiving the slice in any order• Improve end-to-end delay in real-time application

Picture Picture

Internet protocol network

Slice Slice

Start todecode

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Entropy CodingEntropy Coding

CAVLC (Context Adaptive Variable Length Coding)– Context : already coded information of the neighboring

blocks and the coding status of the current block– Optimized VLC tables are provided for each context to

code the coefficients in different statistical conditions

CABAC (Context Adaptive Binary Arithmetic Codes)– Use a binary arithmetic coding engine– Compression improvement is consequence of

• Adaptive probability estimation• Improved context modeling scheme

– Exploiting symbol correlations by using contexts– Average bit-rate saving over CAVLC 5~15%

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ProfilesProfiles

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Comparison to Previous StandardsComparison to Previous Standards

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ConclusionConclusion

H.264 is the standard of both ITU-T VCEG and ISO/IEC MPEG

gains in compression efficiency of up to 50% compared to previous standards

New key features are:– Enhanced motion compensation– Small blocks for transform coding– Integer transform– Improved deblocking filter– Enhanced entropy coding

Increased complexity relative to prior standards

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ReferencesReferences

Ralf Schafer, Thomas Wiegand and Heiko Schwarz, “The emerging H.264/AVC standard,” in EBU technical review, Jan. 2003.

Jorn Ostermann et al., “Video coding with H.264/AVC: Tools, Performance, and Complexity,” in IEEE Circuit and systems magazine, first quarter. 2004.

Thomas Wiegand et al., “Overview of the H.264/AVC Video Coding Standard,” in IEEE transactions on circuits and systems for video technology, Vol. 12, No.7, July. 2003.

M. Mahdi Ghandi and Mohammad Ghanbari, “The H.264/AVC Video Coding Standard for the Next Generation Multimedia Communication,” in IAEEE Jounal.