1. 1 Department of Electrical Engineering, Stanford University Anne Aaron, Shantanu Rane, Eric Setton and Bernd Girod Transform-domain Wyner-Ziv Codec for Video

2. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 2 Overview  Low-complexity video encoding  Transform-domain Wyner-Ziv video codec  Simulation results

3. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 3 Interframe Video Compression Current video standards  Interframe predictive coding for compression  Encoder is 5-10 times more complex than decoder X’ i-1 Interframe Encoder Interframe Decoder XiXi Xi’Xi’ Standard codec

4. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 4 Low-complexity Video Coding Interframe Decoder Intraframe Encoder XiXi X i-1 ’ Xi’Xi’ Proposed codec Wyner-Ziv Coding Lossy source coding with decoder side information Side Information Low-complexity encoding, possibly more complex decoding Applications: video sensors for surveillance, wireless PC cameras, mobile camera phones Similar work: [Puri and Ramachandran, Allerton 2002, ICASSP 2003, ICIP 2003]

5. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 5 Distributed Source Coding Encoder Decoder Statistically dependent Slepian-Wolf Theorem Encoder Decoder Wyner-Ziv Theorem Statistically dependent

6. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 6 Wyner-Ziv Pixel Video Codec Interframe Decoder Scalar Quantizer Turbo Encoder Buffer WZ frames W Intraframe Encoder Turbo Decoder Request bits Slepian-Wolf Codec Interpolation/ Extrapolation Reconstruction Y Key frames K Conventional Intraframe coding Conventional Intraframe decoding W’ K’ [Aaron, Zhang, and Girod, Asilomar 2002] [Aaron, Rane, Zhang, and Girod, DCC 2003] [Aaron, Setton and Girod, ICIP 2003] Side information

7. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 7 Wyner-Ziv DCT Video Codec WZ frames W Request bits Interpolation/ Extrapolation Reconstruction Key frames K Conventional Intraframe coding Conventional Intraframe decoding DCT For each transform band k K’ W’ Y YkYk XkXk Xk’Xk’ IDCT Decoded WZ frames level Quantizer DCT Turbo Encoder Buffer Turbo Decoder Extract bit- planes qkqk bit-plane 1 bit-plane 2 bit-plane M k … qk’qk’ Interframe Decoder Intraframe Encoder level Quantizer DCT Turbo Encoder Buffer Turbo Decoder Extract bit- planes Interpolation/ Extrapolation Side information

8. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 8 Each coefficient band is quantized using a scalar quantizer with levels. Quantizers 6432168 321684 844 8441 321684 844 8441 4411 32841 8411 4111 1111 16811 8111 1111 1111 level Quantizer WZ frame W 4x4 DCT XkXk qkqk For each transform band k Combination of quantizers determines the bit allocation across bands. M k = number of bit planes for k th coefficient band DC band Sample quantizers: Values represent number quantization levels for coefficient band Highest freq AC band

9. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 9 RCPT-based Slepian-Wolf Codec Turbo Encoder Buffer Turbo Decoder Request bits Extract bit- planes bit-plane 1 bit-plane 2 bit-plane M k … qk’qk’ qkqk YkYk Bit planes of coefficients are encoded independently but decoded successively Rate-compatible punctured turbo code (RCPT)  Flexibility for varying statistics  Bit rate controlled by decoder through feedback Turbo decoder can perform joint-source channel decoding

10. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 10 Flexible Side Information Interpolation/ Extrapolation Y Decoded frames Side information To generate side information  Interpolation or extrapolation  With or without motion-compensation (MC) Flexibility in design for decoder Laplacian residual model between transform coefficients of side information and of current frame. Different Laplacian parameter for each coefficient band.

11. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 11 2 dB 11 dB Compression Performance Mother and Daughter QCIF sequence Alternating key frames and Wyner-Ziv frames (K-W-K-W) Slepian-Wolf codec: Rate 4/5 Turbo code Side information –  MC-Interpolation  MC-Extrapolation

12. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 12 3 dB 8 dB Compression Performance Foreman QCIF sequence Alternating key frames and Wyner-Ziv frames (K-W-K-W) Slepian-Wolf codec: Rate 4/5 Turbo code Side information –  MC-Interpolation  MC-Extrapolation

13. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 13 Low-Complexity Side Information To decrease complexity in generating side information  Average Interpolation  Previous frame copy For low-motion sequences, minimal performance degradation Transform-domain codec

14. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 14 Low-Complexity Side Information

15. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 15 Low-Complexity Side Information Side information Average Interpolation After Wyner-Ziv Coding 370 kbps

16. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 16 H263+Intra vs WZ Codec H263+ Intraframe Coding 330 kbps, 32.9 dB Wyner-Ziv Codec 274 kbps, 39.0 dB WZ codec: Transfor-domain, side information using MC-Interpolation. Only WZ-frames shown

17. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 17 H263+ I-B-I-B 145 kbps, 40.4 dB Wyner-Ziv Codec 156 kbps, 37.5 dB H263+Inter vs WZ Codec WZ codec: Transfor-domain, side information using MC-Interpolation. Only WZ-frames shown

18. Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 2004 18 Conclusion A new video compression system with intraframe encoding but interframe decoding Low-complexity encoding for applications such as mobile camera phones and video surveillance networks, wireless PC cameras Transform-domain codec performs up to 2 dB better than pixel-domain scheme Compared to H.263+  Up to 11 dB better than Intraframe coding  Performance gap from H.263+ interframe coding