efficient multi-frame motion estimation algorithms for mpeg-4 avc/jvth.264 mei-juan chen, yi-yen...
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Efficient multi-frame motion Efficient multi-frame motion estimation algorithms for estimation algorithms for MPEG-4 AVC/JVTH.264MPEG-4 AVC/JVTH.264
Mei-Juan Chen, Yi-Yen Chiang, Hung-Ju Li and Ming-Chieh ChiISCAS 2004
OutlineOutline
IntroductionIntroduction FDVSFDVS
– FDVS for multi-frameFDVS for multi-frame– FDVS for multi-frame in H.264FDVS for multi-frame in H.264
VADSVADS– VADVS in H.264
Refinement Experiment Conclusion
BackgroundsBackgrounds
H.264 can refer from previous 1~5 frames, that can get smaller prediction error and obtain better performance.
MPEG-4 AVC/JVT/H.264 motion estimation involves considerable complexity, which increases linearly with the number of reference frames.
IntroductionIntroduction
In multi-frame motion estimation, we reuse the motion information of each frame to its previous one frame for obtaining the MV.
IntroductionIntroduction
Forward Dominant Vector Selection (FDVS) for multi-frame motion estimation in h.264
Variable block size Activity Dominant Vector Selection (VADVS) in H.264
Refinement for the Composed MV
FDVS for multi-frameFDVS for multi-frame
FDVS : For frame-rate conversion– new MVs for outgoing bit-stream need t
o be computed– generates the outgoing MV from the inc
oming MVs instead of performing the full-scale motion estimation
FDVSFDVS
MV(n-2)(estimated)=MV1+ MV2=I(n)
1+I(n-
1)2
FDVS for multi-frameFDVS for multi-frame
Dominant MV : MV carried by a dominant macroblock
Dominant macroblock : macroblock has the largest overlapping segment with the block pointed by the incoming motion vector
FDVS for multi-frameFDVS for multi-frameCurrentFrame
Ref.0Frame
FDVS for multi-frame motion estimation in h.264 H.264 standard can 16x16, 16x8,
8x16, 8x8, 8x4, 4x8, and 4x4 block size to perform the motion compensation.
Therefore, we must store the seven block size MV with for FDVS algorithm for the previous reference frame.
FDVS for multi-frame motion estimation in h.264 Variable block size in h.264 (16x16 8x8 4x4)Variable block size in h.264 (16x16 8x8 4x4)
MV5=I1(n)+I2(n-1)+I1(n-2)+I4(n-3)+I3(n-4)
FDVS for multi-frame motion estimation in h.264 Variable block Variable block
size in h.264size in h.264 16x8 and 8x416x8 and 8x4 8x16 and 4x88x16 and 4x8
Variable block size Activity Dominant Vector Selection (VADVS) FDVS selects the dominant block wit
h the largest overlapping area from the four neighboring blocks.
ADVS algorithm utilizes the activity information of the macroblock.– Counting the numbers of NZ (nonzero q
uantized DCT coefficients) of covered 8x8 residual blocks represents the activity information of a macroblock.
VADVS
8x8 dct residual
VADVS in h.264
In H.264 standard, residual coding uses 4X4 block size to perform the transformation.
H.264 standard uses integer transform instead of the DCT transform.
Dominant MV : the MV carried by a dominant block.
dominant block : block that has the maximum NZ
VADVS in h.264
Refinement for composed Refinement for composed MVMV
A composed MV is usually not optimal because each dominant motion vector is an approximated value of the optimal MV.
Horizontal and Vertical Search (HAVS) to refine the composed motion vector.
Refinement for composed Refinement for composed MVMV
ExperimentExperiment
bit-rate variation is less than 2%
ExperimentExperiment
PSNR difference is less than 0.1dB compared with the reference software JM61E_REF5.
ExperimentExperiment
ConclusionConclusion
In this paper, we propose the efficient algorithms to improve the coding speed by 4 times in average, and maintain the performance.