Systematic Lossy Forward Error Protection for Video Waveforms

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Systematic Lossy Forward Error Protection for
Video Waveforms
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Overview

• Error Resilient Digital Video Broadcasting
• Systematic Lossy Forward Error Protection
• Embedded Wyner-Ziv Coding
• Improved Wyner-Ziv Video Codec

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Error-Resilient Digital Video Broadcasting

• Forward Error Correction (FEC)
• Cliff effect
• For graceful degradation, Priority Encoding
  Transmission (PET) Albanese, et al., 1996
• Layered representation incurs a rate-distortion
  penalty
• Forward Error Protection (FEP)
• Protects the video waveform
• Graceful degradation without layered
  representation

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Related Work

• Bounds for systematic lossy source-channel coding
  
• Shamai, Verdu and Zamir, 1998

Y
Channel A
uncoded
Side information
X
Encoder
Decoder
Channel D
X

• Enhancing analog transmission systems using
  digital side information Pradhan and
  Ramchandran, 2001
• Robust predictive coding Sehgal and Ahuja,
  2003

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Systematic Lossy Forward Error Protection
MPEG Encoder
MPEG Decoder with Error Concealment
S
S
Error-Prone channel

• Protects the original video waveform
• Lossy protection

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Results
Carphone CIF, 50 frames _at_ 30fps 1 Mbps, 1
macroblock loss
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Wyner-Ziv Coding (16 quantization levels,
0.75bpp)
Error Concealment only (No WZ bits)
Carphone CIF, 1 Mbps, 1 macroblock loss
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Embedded Wyner-Ziv Codec
MPEG Encoder
MPEG Decoder with Error Concealment
S
S
Error-Prone channel

• Graceful degradation of video quality
• Does not require layered representation

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Results2-level Wyner-Ziv Codec
Carphone CIF, 50 frames _at_ 30fps 1 Mbps, 1
macroblock loss
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Systematic Lossy Forward Error Protection
MPEG Encoder
MPEG Decoder with Error Concealment
S
S
Error-Prone channel
Slepian-Wolf Encoder
Slepian-Wolf Decoder
Reconstruction
Coarse Quantizer
S
Wyner-Ziv Encoder
Wyner-Ziv Decoder
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Improved Wyner-Ziv Coder
S
Error-Prone channel
Common reference frame
Rane, Aaron, Girod (submitted to VCIP 04)
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Systematic Lossy FEP vs. FEC Foreman.cif
FEC Main Stream _at_ 1.092 Mbps FEC (n,k) (40,36)
FEC bitrate 120 Kbps Total 1.2
Mbps Proposed Scheme Main Stream _at_ 1.092 Mbps WZ
Stream _at_ 270 Kbps FEP (n,k) (52,36) WZ bitrate
120 Kbps Total 1.2 Mbps

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1 Mbps 120 kbps FEC (33.03 db)
1 Mbps 120 kbps FEP (38.40 db)
Foreman CIF, 50 frames, symbol error rate 10-3
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Summary

• A novel systematic lossy forward error protection
  scheme for error-resilient video broadcasting
• Wyner-Ziv coding applied to forward error
  protection
• Advantages
• More robust than FEC over a wide range of error
  rates
• Graceful degradation without layered video
  representation
• Backward-compatible