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Hash-Aided Motion Estimation

Hash-Aided Motion Estimation. Alwin Anbu and Argyrios Zymnis. Outline. Motivation Approach to Problem Results Conclusion. Motivation. ME computationally intensive Usually performed at Encoder to reduce Decoder complexity Distributed Video Coding, aimed at reducing encoder complexity

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Hash-Aided Motion Estimation

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  1. Hash-Aided Motion Estimation Alwin Anbu and Argyrios Zymnis

  2. Outline • Motivation • Approach to Problem • Results • Conclusion

  3. Motivation • ME computationally intensive • Usually performed at Encoder to reduce Decoder complexity • Distributed Video Coding, aimed at reducing encoder complexity • Hash-Aided ME at Decoder

  4. Typical Hash-Aided ME System

  5. Approach to Problem • Linear Transform • Quantisation • Rate Calculation • ME rule

  6. Linear Transformation • Identity: Full Block and Sub-Sampled Block • DCT: Low-frequency and Highest-Energy Coefficients • DFT: Low-frequency Coefficients

  7. Quantisation • Same uniform quantiser for all coefficients • Optimized uniform quantiser for each group of coefficients. • LMQ and EC-LMQ

  8. Rate Calculation • Independent encoding of coefficients • Zig-Zag scanning followed by runlength-amplitude coding • Use of hash storage

  9. Motion Estimation Rule • Invert hash (if possible) and minimize SSD in the spatial domain • Transform each block in the search region and minimize SSD in the transform domain: extra computational overhead

  10. R-D Performance of Identity

  11. No. of Low-frequency Coeffs

  12. Results • DCT performs better than identity • Decreasing Gains for using more Low-frequency Coefficients • Low-frequency and Highest-energy performance about the same • Use 12 Low-frequency DCT coefficients

  13. System Performance

  14. Comparison with prior method

  15. Conclusions • DCT is good for hash generation • Small number of low-frequency coefficients required • Optimizing quantiser widths should improve results

  16. Acknowledgements • We would like to thank Rajiv for his help, even though he was not enrolled for the course • We would like to thank David and Shantanu for their suggestions

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