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Brief Overview of Wyner-Ziv CODEC and Research Plan. Jin-soo KIM. Contents. Overview of Wyner-Ziv CODEC Application of Wyner-Ziv CODEC Basic Principle of WZ CODEC Generation of S.I. at the Decoder How to Encode WZ frames Research Plan Q&A. Application of WZ CODEC. 2010.

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contents
Contents
  • Overview of Wyner-Ziv CODEC
    • Application of Wyner-Ziv CODEC
    • Basic Principle of WZ CODEC
    • Generation of S.I. at the Decoder
    • How to Encode WZ frames
  • Research Plan
  • Q&A
slide4

2010

Coding Efficiency

Network awareness

+ implementation?

2005

HDTV

SVC

H.264

2003

Mobile TV

MPEG4

1999

Hand PC

Video Conferencing

MPEG2

H.263

Mobile Phone

1994

1992

MPEG1

Year

Video coding : history and trends

H.265(?)

mobile

  • Mobile : 3low1high
  • Low (battery, bandwidth, CPU)
  • High cost
conventional interframe video coding
(Conventional) Interframe Video Coding

PredictiveInterframe Encoder

PredictiveInterframe Decoder

X’

Side Information

low complexity encoder
Low Complexity Encoder

Wyner-ZivIntraframe Encoder

Wyner-ZivInterframe Decoder

X’

Side Information

[Witsenhausen, Wyner, 1980]

[Puri, Ramchandran, Allerton 2002]

[Aaron, Zhang, Girod, Asilomar 2002]

applications of wz codec
Applications of WZ codec
  • Light encoder and light decoder

B. Girod, A. Aaron, S. Rane, D. Rebollo-Monedero, “Distributed video coding,” Proceedings of the IEEE, Vol93, pp71-83, Jan. 2005.

applications of wz codec http www discoverdvc org deliverables discover d4 pdf
Applications of WZ codechttp://www.discoverdvc.org/deliverables/Discover-D4.pdf
  • Wireless low power video surveillance
  • Disposable video cameras
  • Sensor network
  • Multi-view image acquisition
  • Medical applications
  • Networked camcoders
applications of wz codec http www discoverdvc org deliverables discover d4 pdf1
Applications of WZ codechttp://www.discoverdvc.org/deliverables/Discover-D4.pdf
  • SensorCamPillCamWearableCamDisposable cam.ScanCam
slide11

Lossless Compression with Side Information

R≥ H(X|Y)

Encoder

Decoder

Statistically dependent

Side Information

Wyner-Ziv showed that the conditional rate-mean squared error distortion function for X is the same whether the side information Y is available only at the decoder, or both at the encoder and the decoder.

R≥ H(X|Y)

Encoder

Decoder

Statistically dependent

[Slepian, Wolf, 1973]

Side Information

shannon theory with side info
Shannon Theory with side info.
  • Example) x : dice number
    • H(X) = 6Σlog26 = 2.58 bits
    • Shannon coding theorem
      • No error, if H(X) < R(X) = 3 bits
      • If R(X) = 2, {00,01,10,11}{1,2,{3,4},{5,6}}
    • With side information Y=“even number”
      • H(X|Y) = 3Σlog23 = 1.58 < R(X|Y) = 2

Information loss

X

X

R

decoder

encoder

Y

wyner ziv coding lossy
Wyner-Ziv coding (lossy)
  • A. Majumdar, R. Puri, P. Ishwar, K. Ramchandran, “Complexity/performance trade-offs for robust distributed video coding,” IEEE ICIP2005, Vol. 2,  pp678-81, 11-14 Sept. 2005
  • WZ = quantization + Slepian-Wolf
  • Random coset partitioning operation,
  • 3bit-info can be represented by 2bit(LSB first  increase Δ)
    • X : original value U : quantized value
    • Y : side information in the decoder
    • given Y + sent 10U=101
history of dvc
History of DVC
  • Slepian and Wolf : lossless DVC (1973)
    • “Noiseless coding of correlated information sources,” IEEE Tr. On Information Theory, 1973.
  • Wyner and Ziv : lossy DVC (1976)
    • “The rate-distortion function for source coding with side information at the decoder,” IEEE Tr. Information Theory, 1976.
  • Ramchandran in Berkeley : PRISM (2002)
    • Power-efficient, Robust, hIgh-compression, Syndrome-based Multimedia coding
  • Girod in Stanford : Good review (2005)
    • “Distributed video coding,” IEEE Proceedings, 2005.
  • EU : DISCOVER(~2006), www.discoverdvc.org
    • DIStributed COding for Video sERvices
towards practical slepian wolf coding
Towards Practical Slepian-Wolf Coding
  • Convolution coding for data compression [Blizard, 1969]
  • Convolutional source coding [Hellman, 1975]
  • Syndrome source coding [Ancheta, 1976]
  • Coset codes [Pradhan and Ramchandran, 1999]
  • Trellis codes [Wang and Orchard, 2001]
  • Turbo codes

[García-Frías and Zhao, 2001]

[Bajcsy and Mitran, 2001]

[Aaron and Girod, 2002]

  • LDPC codes [Liveris, Xiong, and Georghiades, 2002]
  • . . .
  • . . .
motion compensation
Motion Compensation
  • Motion-compensated interpolation (MC-I)using the decoded Key frame at time t-1 & t+1
motion compensation1
Motion Compensation
  • Motion-compensated extrapolation (MC-E)estimate the motion between the Wyner-ziv frame at time t-2 and the Key frame at time t-1
wyner ziv residual video codec
Wyner-Ziv Residual Video Codec

WZ frames

X’

WZ

Decoder

WZ

Encoder

W

X

Xer

Xer

Y

  • Residual of a frame with respect to an encoder reference frame (Xer) is fed into a Wyner-Ziv encoder. To avoid drift, Xer should be replicable at the decoder.
  • Since the decoder takes into account motion, Y is expected to be a better estimate of frame X than Xer. The Wyner-Ziv decoder uses both Y and Xer to calculate the reconstruction X’.

[Aaron, Zhang, Girod, Asilomar 2002]

pixel domain wyner ziv video codec
Pixel-Domain Wyner-Ziv Video Codec

Interframe Decoder

Intraframe Encoder

Slepian-Wolf Codec

WZ frames

Reconstruction

Turbo Decoder

Turbo Encoder

W’

Scalar Quantizer

W

Buffer

Request bits

Side information

Y

Interpolation/ Extrapolation

Key frames

Conventional

Intraframe

decoding

Conventional

Intraframe coding

I

I’

[Aaron, Zhang, Girod, Asilomar 2002]

pixel domain wyner ziv video codec1
Pixel-Domain Wyner-Ziv Video Codec

After Wyner-Ziv Decoding

Decoder side informationgenerated by motion-compensated interpolationPSNR 24.8 dB

16-level quantization – 2.0 bpp0 pixels in errorPSNR 36.5 dB

[Aaron, Zhang, Girod, Asilomar 2002]

dct domain wyner ziv video codec
DCT-Domain Wyner-Ziv Video Codec

Intraframe Encoder

Interframe Decoder

WZ frames

Dk

Dk’

Turbo Encoder

Recon

Scalar Quantizer

Turbo Decoder

W

W’

DCT

IDCT

Buffer

Request bits

Side information

Yk

For each transform band k

DCT

Y

Interpolation/ Extrapolation

Key frames

Conventional Intraframe coding

I

Conventional Intraframe decoding

I’

[Aaron, Zhang, Girod, Asilomar 2003]

rate distortion performance salesman

Interframe 100%

3 dB

6 dB

Rate-Distortion Performance - Salesman

Encoder Runtime

Pentium 1.73 GHz machine

  • Every 8th frame is a key frame
  • Salesman QCIF sequence at 10fps
  • 100 frames

[Aaron, Zhang, Girod, Asilomar 2003]

slide28

Salesman at 10 fps

DCT-based Intracoding 149 kbps PSNRY=30.0 dB

Wyner-Ziv DCT codec 152 kbps PSNRY=35.6 dB GOP=8

[Aaron, Zhang, Girod, Asilomar 2003]

conclusion
Conclusion
  • Increase efficiency of DVC
    • Reduce H(X) : simple ME/MC?
    • Increase H(Y) : better interpolation/extrapolation
    • Stronger correlation between X and Y.

X

X

R

encoder

decoder

Y

X? Y? P(X/Y)

conclusion1
Conclusion
  • Distributed coding is a fundamentally new paradigm for video compression
  • Slepian-Wolf encoding, is fundamentally harder for practical applications due to the general statistics of the correlation channel
  • The rate-distortion performance of Wyner-Ziv coding does not yet reach the performance of conventional interframe coder
  • It is unlikely that distributed video coding algorithm will ever beat conventional video coding schemes in R-D performance
  • Many authors believe that distributed coding techniques will soon complement conventional video coding to provide the best overall system performance and enable novel applications
research plan
Research Plan

Plan

■ Planand achievements

done

Now

slide33
Q&A

Thank you

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