Institut für Informationsverarbeitung Two-dimensional Non-separable Adaptive Wiener Interpolation Filter for H.264/AVC Yuri Vatis Institut für Informationsverarbeitung,

Institut fürInformationsverarbeitung

Two-dimensional Non-separable Adaptive Wiener Interpolation

Filter for H.264/AVC

Yuri Vatis

Institut für Informationsverarbeitung,

Universität Hannover

ITG-FA 3.2, 23.06.2005


2

Outline

• Introduction

• Motion Compensated Prediction

• Adaptive Interpolation Filter

• Experimental Results

• Conclusion


3

Introduction

Hybrid Video Encoder:

+

-

+ +

MCP z -1

T-1

QuantT

ME

EC

Video input Bitstream

s(t)

s’(t-1)

d(t)

e(t)


4

Motion Compensated Prediction (MCP)

s‘(t-1)

block to code

s(t)

reference block

d(t)


5

Motion Compensated Prediction (MCP)

image signal on sub-pel positions has to be generated by interpolation

s’(t-1)

block to code

s(t)

reference block

j

i

Prediction is distorted by:

1. Aliasing in s(t) and s’(t-1)

2. Displacement estimation errors of d(t)

3. Quantisation errors in s’(t-1)

4. etc.

The distortions depend on the motion and content of the video signal

MCP with fractional-pel Motion Vector Resolution

d(t)


6

2D non-separable Adaptive Interpolation Filter

• Analytical design of a non-separable adaptive 2D interpolation filter.

• Goal:– Prediction (and not just interpolation) of picture

elements by minimising prediction error energy.– Reduction of aliasing and blurring effects, motion

estimation errors.

• Properties:– Symmetric, non-separable 6x6-tap filter.– Filter coefficients are calculated analytically once per

frame with respect to all reference frames.


7

Adaptive Interpolation Filter

• Value ( ) to be interpolated:

where is an integer sample value ( ) and are filter coefficients for sub-pel position SP

SPp A1 A2 A3 A4 A6

B5 B6

C5

B1 B2

C1 C2

D1 D2

E2

D3 D4

E3 E4

D5 D6

E5 E6

B3 B4

C4

A5

C6

E1

F1 F2 F3 F4 F5 F6

C3 a c

d e g

i j k

l m n

b

f

o

h

oaSP ,,

6

1

6

11,1,

i j

SPjiji

SP hPp

jiP ,

SPjih ,

61 FA


8

Analytical Calculation of Filter Coefficients

The calculation of coefficients and the motioncompensation are performed in the following 3 steps:

1) Displacement vectors are estimated for every image to be coded (standard interpolation filter is used).

2) Independent calculation of 2D filter coefficients for each sub-pel position by minimisation of the prediction error energy:

with

mvymvxd t ,

x y i jjyix

SPjiyx

SP PhSe

2

~,~,,

2

FOmvyyyFOmvxxx ~,~


9

Analytical Calculation of Filter Coefficients

3) Estimation of new displacement vectors (applying the adaptive interpolation filter computed in 2). Reducing motion estimation errors, caused by aliasing,

camera noise etc. Treating the problem in the rate-distortion sense.

• The software was declared as a VCEG KTA-Software

]5;0[,

0 ~,~

6

1

6

1

~,~,,,

2

lk

PPhSh

elykx

x y i jjyix

SPjiyxSP

lk

SP


10

Quantisation and Coding of Filter Coefficients

• Quantisation with 8 bits (magnitude).

• Required side information for filter coefficients @30 fps ( [VCIP05] ):

PCM VCIP05

14.6 kbit/s 3-10 kbit/s


11

Results

CIF ( HDTV)

ProfileIDC 100

QPISlice 23, 27, 31, 35

IntraPeriod 0

QPPSlice 24, 28, 32, 36

NumberBFrames 3

QPBSlice 25, 29, 33, 37

BReferencePictures 1

PyramidCoding 1

PyramidLevelQPEnable 1

SearchRange 32 (64)

NumberReferenceFrames 5 (3)

SymbolMode 1

AdaptiveRounding 1

Transform8x8 1


12

Concrete, CIF, 400 Frames @ 30 fps

26

27

28

29

30

31

32

33

34

35

36

37

38

0 1000 2000 3000 4000

bit rate [kbit/s]

Y-P

SN

R[d

B]

H.264/AVC

KTA

KTA+B


13

Crew, HDTV(720p), 20 Frames @ 60 fps

35

36

37

38

39

40

41

42

0 2 4 6 8 10

bit rate [Mbit/s]

Y-P

SN

R[d

B]

H.264/AVC

KTA

KTA+B


14

Raven, HDTV(720p), 40 Frames @ 60 fps

36

37

38

39

40

41

42

43

44

0 1 2 3 4 5 6

bit rate [Mbit/s]

Y-P

SN

R[d

B]

H.264/AVC

KTA

KTA+B


15

Sunflower, HDTV(1080p), 100 Frames @ 25 fps

37

38

39

40

41

42

43

44

45

0 1 2 3 4

bit rate [Mbit/s]

Y-P

SN

R[d

B]

H.264/AVC

KTA

KTA+B


16

Conclusions

• Average of 12% bit rate savings compared to the standard H.264/AVC

• Slightly increased decoder complexity Number of operations needed for interpolation is

increased Suitable for 24-bit arithmetic

Documents

Institut für Informationsverarbeitung Two-dimensional Non-separable Adaptive Wiener Interpolation Filter for H.264/AVC Yuri Vatis Institut für Informationsverarbeitung,