deblocking filter
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DEBLOCKING FILTER
Present: Pham Ngoc Giao
Professor: Kim - Jong Nam
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Contents
Position of deblocking filter in H.264?1
Why H.264 use deblocking filter?2
Function and operation of deblocking filter 3
4 Reference
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Position of deblocking filter
Transform &Quantization
Motion
Estimation
MotionCompensation
PictureBuffering
EntropyCoding
IntraPrediction
Intra/Inter ModeDecision
Inverse Quantization& Inverse Transform
DeblockingFilter
+
-
++
Video Input
Bitstream
Output
Encoder H.264
Using Inter mode
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Position of deblocking filterDecoder H.264
MotionCompensation
EntropyDecoding
IntraPrediction
Intra/Inter ModeSelection
Inverse Quantization& Inverse Transform
DeblockingFilter
+
+BitstreamInput Video
Output
PictureBuffering
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Why H.264 use deblocking filter
After inverse quantization and inverse transform, macroblocks have blocking
distortion and blocking artifacts. Thus, frame image is used for motion estimation
and motion compensation in inter mode, has noise and errors => using blocking
filter to reduce noise, smooth blocks and improve frame.
MotionCompensation
EntropyDecoding
IntraPrediction
Intra/Inter ModeSelection
Inverse Quantization& Inverse Transform
DeblockingFilter +
+BitstreamInput Video
Output
PictureBuffering
Noise, distortion and artifacts
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Function of deblocking filter
Reduceblocking
distortion
Improvequality of decodedpicture
Reduceblockingartifacts
Smoothblockedges
functions
Deblocking filter:
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Operation of deblocking filter
Filtering is applied to horizontal or verticaledges of 4 x 4 blocks in a macroblock,adaptively on the several levels: slice, block-edge, sample
Vertical edges(chroma)
Vertical edges(luma)
Horizontal edges(luma)
Horizontal edges(chroma)
16*16 Macroblock 16*16 Macroblock
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Operation of deblocking filter
Each filtering operation affects up to three samples oneither side of the boundary. The strength of the filter (theamount of filtering) depends on the current quantiser, thecoding modes of neighbouring blocks and the gradient ofimage samples across the boundary
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Operation of deblocking filter
Determine Boundary strengths: H264/MPEG4 has a set offour boundary strengths
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Operation of deblocking filter
Decision Filter:
+ A group of samples from the set (p2, p1, p0, q0, q1,
q2) is filtered only if:(a) BS > 0 and
(b) |p0 q 0|
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Operation of deblocking filter
Determine valid edge:
In a given MB an edge is selected for de-blocking
if : the slice to which the current MB belongs is
enabled for de-blocking the corresponding neighboring block is
available
For the horizontal edge of a field mode block in a
frame, both the lines 0 and 1 of the block are selected
for de-blocking if the top-right macro-block pair is a
field MB
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Operation of deblocking filter
Da
Data flow for de-blocking process
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Operation of deblocking filter
Da
Algorithm for data flow
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Operation of deblocking filter
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Operation of deblocking filter
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Operation of deblocking filter
[1] ITU-T Recommendation, H.264 Advanced VideoCoding for Generic Audiovisual Services, 03/2005
[2] ITU-T Recommendation, H.264.1 ConformanceSpecification for H.264 Advanced Video Coding, 03/2005
[3] Iain E. G. Rechardson, H.264 and MPEG-4 VideoCompression, John Wiley and Sons, 2003
[4] Wu Di, Gao Wen, Hu Mingzeng, Ji Zhenzhou, An Exp-Golomb Encoder and Decoder Architecture forJVT/AVS, IEEE, 2003
[5] Overview of the H.264/AVC Video Coding StandardThomas Wiegand, Gary J. Sullivan, Senior Member, IEEE,
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