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Fast Mode Decision for Multiview Video Coding

Liquan Shen, Tao Yan, Zhi Liu, Zhaoyang Zhang, Ping An, Lei Yang

ICIP2009

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Outline

• Observation and Analysis • Fast Mode Decision for Multiview Video Coding• Experiment Results

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Observation and Analysis

• JMVM 6.0• Inter slices

Decide in advance whether the mode

size for a MB is 16x16 or not

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Observation and Analysis

• For MBs in regions with active motion or rich texture, their MB prediction mode size are diverse.

• For MBs in region with homogeneous motion and texture, their prediction mode size are always large.

• Mode Complexity(MC) parameter : derived from the mode context of MBs in the previously coded view to estimate the mode characteristics of the MB in current view.

– Use means of global disparity vector(GDV) which is not exactly disparity between current MB and the corresponding one.

– Use its eight neighbor MBs

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Observation and Analysis

• The mode complexity of a MB(MDC) is defined:

– is the MB-mode factor

– is the number of MBs

• The larger the mode factor, the more complex the MB is.• Use determine a MB’s region:

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Fast Mode Decision for Multiview Video Coding

• Mode size distributions for each type of MB with different mode complexity computed as Eq2.

98 1 85 7 2 70 >5

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Fast Mode Decision for Multiview Video Coding

• Stategy – Simple mode : only mode size of 16x16 is tested, other mode sizes are skipped.– Medium simple mode : mode size of 8x8 is skipped.– Complex mode : all mode size are tested.

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Experiment Results

• JMVM 6.0• CABAC• Variable prediction size and loop filter is turned on• GOP is 16• QP is with 20, 24, 28, 32 and 36

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Motion Skip Mode using Dynamic Property of Anchor Pictures in

Multiview Video Coding

Choonghyun Jung, Kwangmu Shin, Kidong ChungSSIAI 2010

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Outline

• Introduction• Proposed Motion Skip Mode • Experiment Results

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Introduction

• Motion skip mode: skips the motion data of the current view in encoding and infers motion data of adjacent views in decoding.

• It is important to get the correlation of the current view and the adjacent view.

• If the motion skip mode is selected by comparing RDcost, no futher motion information such as the macroblock mode, the reference frame index and the motion vector, needs to be transmitted.

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Introduction

• Global Disparity Vector(GDV)

– R : number of pixels overlapped– () : disparity vector with minimized MAD between images.

Not exact reveal the correlation between the current and adjacent view.

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Introduction

• Regional Disparity Vector(RDV)

– The bit-rate of the RDV is increased because the RDV needs to encode region information per macroblock

Propose a regional disparity map based motion skip mode using dynamic property of anchor pictures in MVC

The anchor picture is coded only inter-view prediction, its motion vectors can be considered as disparities.

Some macroblock are coded as intra mode will be compensated by the closest non-intra macroblock.

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Proposed Motion Skip Mode

• Disparity Calculation using the Anchor Picture– Regional disparity map is generated to calculate regional disparity vector by exploiting

the anchor picture of current view and adjacent view per GOP

• Steps:– The luminance value difference between two anchor pictures is calculated

• Brighter regions represent regions that have movements

• Darker regions represent regions with less-movements – Binarization

• Divide into two regions (movement and less-movement )– The binary picture is segmented into macoblocks– The number of pixels of macroblock is investigated– The regional disparity map is generated

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Proposed Motion Skip Mode

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Proposed Motion Skip Mode

• The best matching disparity vectors are calculated using MAD between the divided regions of current view(movement and less-movement regions) and the reference pictures of adjacent views.

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Proposed Motion Skip Mode

• Motion Skip Mode using Regional Disparity– Since the disparity vectors and the disparity map are calculated in the anchor pictures,

we should apply the motion skip mode in the non anchor pictures

– If the proposed motion skip mode is selected by comparing the RDcost of the other modes, no further motion information such as the macroblock mode, the reference index, the motion vector is transmitted

– New flags of three bits which are included in the head of macroblock layer syntax• Notify whether or not the motion skip mode is used • Notify whether or not the the region has motions• Notify whether or not the picture of adjacency view is used

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Experimental Result

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Experimental Result