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

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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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]

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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, Each coefficient band is quantized using a scalar quantizer with levels. Quantizers 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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.

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

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

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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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

Aaron, et al: Transform-domain Wyner-Ziv Codec for Video Jan. 21, 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