Towards Practical Wyner-Ziv Coding of Video

1. Interframe Decoder Foreman Interpolated side information Extrapolated side information X4 X2 X2 X4 K1 K1 K5 K1 K5 K3 Foreman Hall Monitor Foreman H.263+ I-B-I-B 145 kbps Wyner-Ziv-DCT 141 kbps DCT coding 175 kbps Towards Practical Wyner-Ziv Coding of Video Anne Aaron, Eric Setton, Bernd Girod Department of Electrical Engineering, Stanford University Summary Wyner-Ziv Codec Problem: • Low-complexity encoding • ~10 times faster than DCT-based intraframe coding • ~100 times faster H.263+ interframe (I-B-I-B) coding • Rate-control by decoder • Inherent joint-source channel decoding Develop a video compression scheme withlow-complexity encoders for applications such as mobile video phones, wireless PC cameras and video surveillance systems Intraframe Encoder Interframe Decoder WZ frames Reconstruction Scalar Quantizer Turbo Encoder Turbo Decoder Buffer X X’ Our Approach: Request bits Y Intraframe Encoder side information Xi Xi’ Interpolation/ Extrapolation Key frames Wyner-Ziv Coding source coding with decoder side information • For better compression efficiency, transform-domain codec – perform Wyner-Ziv coding on each transform band Conventional Intraframe decoding Conventional Intraframe coding Xi-1’ K’ K Result: Low-complexity encoding with high compression efficiency 1 to 10 dB better than DCT-based intraframe coding To appear[Aaron, Rane, Setton and Girod, VCIP-2004] Compression Results Same Encoder – Different Decoders Multiple Wyner-Ziv Frames Alternating key frames and Wyner-Ziv frames Side information from motion-compensated interpolation • Decoder generates the side information and performs rate-control so the same encoder works for different types of decoders • Complexity vs. compression efficiency trade-off at the decoder Increasing the number of Wyner-Ziv frames between key frames reduces bit rate of key frames but makes the side information less reliable