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A frequency domain approach for Intra-coding pictures

A frequency domain approach for Intra-coding pictures. Presenter: Andy C. Yu for Microsoft Research Cambridge 16 th May 2006. Outline:. Introduction - H.264/AVC Intra coding v. Motion JPEG-2000 coding. The proposed Fintra algorithm – based on frequency domain

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A frequency domain approach for Intra-coding pictures

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  1. A frequency domain approach for Intra-coding pictures Presenter: Andy C. Yu for Microsoft Research Cambridge 16th May 2006

  2. Outline: • Introduction - H.264/AVC Intra coding v. Motion JPEG-2000 coding. • The proposed Fintra algorithm– based on frequency domain • Simulation results – comparison with state-of-the-art algorithms • Conclusions

  3. Introduction • H.264/AVC is standardised by ITU-T and MPEG ISO/IEC in Dec. 2001 for commercial video coding. • It represents a major step forward in the development of video standards*. • It typically outperforms all existing standards by a factor of two. • Another important fact is that H.264/AVC is a public and open standard*. * R. Schäfer, T. Wiegand and H. Schwarz, “The emerging H.264/AVC standard”, EBU Technical Review, Jan 2003

  4. 8 8 … Video Sequence 8x8 DCT Quantization Process (Lossy) Entropy Coding Decomposition … Conventional Intra-coding structure

  5. 4 4 … Video Sequence Integer 4x4 DCT & Quantisation Process Entropy Coding Decomposition … Mode Selection Predicted block Original block Residue Data H.264/AVC Intra-coding structure

  6. Q A B C D E F G H I a b c d J e f g h K i j k l L m n o p M N O P A : Neighbouring sample that are already reconstructed at the encoder and decoder sides. a : Samples to be predicted. Intra-Prediction in H.264/AVC

  7. Picture from I. Richardson, H.264 and MPEG-4 Video Compression, Willey Publisher, 1st edition, 2003.

  8. Picture from I. Richardson, H.264 and MPEG-4 Video Compression, Willey Publisher, 1st edition, 2003.

  9. Lagrangian Evaluation • Final mode decision is selected to minimise Lagrangian cost. • Where D: measure of the distortion R: the number of bits. λ: Lagrange parameter. Qp: Quantisation factor.

  10. Lagrangian evaluation (cont.)

  11. H.264 Intra-coding v. Motion JPEG2000 coding Picture from J. Ostermann, J. Bormans et al., “Video Coding with H.264/AVC: Tools, Performance, and Complexity,” IEEE Circuits and Systems Magazine, first quarter, 2004

  12. The Proposed Fast Intra-coding Algorithm (Fintra)

  13. 4 4 … Video Sequence Integer 4x4 DCT & Quantisation Process Entropy Coding Decomposition … Mode Selection Predicted block Original block Residue Data H.264/AVC Intra-coding structure

  14. 4 4 … Video Sequence Integer 4x4 DCT & Quantisation Process Entropy Coding Decomposition … Mode Selection Predicted block Original block Residue Data H.264/AVC Intra-coding structure

  15. The search strategy for the proposed Fintra algorithm • The proposed algorithm selects fewer modes to undergo full Lagrangian cost evaluation. • The entire selection process operates in the discrete cosine transform (DCT) domain. • Generally, larger residue block energy is produced by intra-coding. • It is observed that the modes that provide the least residue energy will result in minimum R and hence minimise the Lagrangian cost.

  16. Algorithm formulation • The selection criterion can be measured from the SAD of residue block in Discrete Cosine Transform domain: The definition of 2D-DCT is:

  17. Thus, the selection is the least residue energy produced by the mode. • We separate the low frequency spectrum, DC, from other AC frequencies.

  18. DC and low-frequency AC coefficients contain more energy than the high-frequency coefficients.  Task: Develop efficient approach to calculate DCP|mode and ACP|mode(i)

  19. 17x1

  20. . 9x17 17x1

  21. . = 9x1 9x17 17x1

  22. . = 9x1 9x17 17x1

  23. Thus, the selection process, becomes

  24. Compared with 2D-DCT ? General practice: apply 1D-DCT twice, row-wise and column-wise ?

  25. General Practice: 0.1 X (B + D + J + L – F – H – N - P) + 0.2 X (C + K - G - O)  2 Multiplication + 11 Addition operators

  26. Features of conversion matrix Ω • Uniquely existed at each position in frequency domain. • Independent of the video sequences. • Low computational demand. • The coefficients can be calculated and stored in advance.

  27. We may select at least 2 modes to undergo the full Lagrangian process.

  28. Simulations and Results • Comparison of the results with the two best performing algorithms detailed in the literatures. • Simulation Settings • JM6.1e version in Microsoft Visual C++ • Various values of M are selected. • Measurements:picture quality (dB), compression ratio (Kbits/sec) and entire encoding time (sec).

  29. Simulation 1: Compared with C. Kim, H. Shih, and C. Kuo, “Fast H.264 Intra-prediction mode selection using joint spatial and transform domain features”,Journal of Visual Communication and Image Representation, vol. 17, pp. 291-310, 2006. by selecting M=3

  30. 44 JM6.1e Proposed 42 Result in [6] 40 38 36 PSNR (dB) 34 32 30 28 26 0 200 400 600 800 1000 1200 1400 1600 1800 Rate (Kbits/sec) Foreman QCIF 30Hz 300 frames All Intra-coding

  31. Foreman QCIF 30Hz 300 frames All Intra-coding Perception sensitivity area

  32. 44 JM6.1e Proposed 42 Result in [6] 40 38 36 PSNR (dB) 34 32 30 28 26 0 200 400 600 800 1000 1200 1400 1600 1800 Rate (Kbits/sec) Foreman QCIF 30Hz 300 frames All Intra-coding

  33. JM6.1e Proposed Result in [6] Foreman QCIF 30Hz 300 frames All Intra-coding

  34. JM6.1e Proposed Result in [6] Foreman QCIF 30Hz 300 frames All Intra-coding Δ1≈0.1dB Δ2≈0.3dB

  35. Simulation 2: F. Pan, X. Lin, et al., “Efficient prediction mode selection 4x4 blocks in H.264,”JVT-013, ISO/IEC JTC1/SC29/ WG11 and ITU-T SG16 Q.6, Mar. 2003, Pattaya, Thailand. F. Pan, X. Lin, et al., “Fast mode decision algorithm for Intraprediction in H.264/AVC video coding,” IEEE transaction on Circuits and Systems for Video Technology, pp. 813-823, Jul. 2005. by selecting M=2

  36. Conclusions • A fast algorithm using matrix formulae in the DCT domain is presented. • The proposed Fintra algorithm does not need any a priori knowledge or magic number. • The simulation results verify that the proposed algorithm outperforms two other algorithms in terms of all measurements. • The rate-distortion curves show that the proposed algorithm achieves the same coding performance, yet reduces the computation requirement by up to 75%.

  37. Future Work • The proposed Finter algorithm has been developed to achieve speed up for encoding P- and B- frames. • The Finter algorithm produces competitive results to other algorithms recorded in the literatures. • An integration for both proposed Fintra and Finter algorithms has been done to attain a time of saving up to 86% without sacrificing both picture quality and bit rate efficiency.

  38. References [1] Andy C. Yu, Ngan King Ngi, and Graham Martin, “Efficient Intra- and Inter-mode Selection Algorithms for H.264/AVC,” in Journal of Visual Communication and Image Representation – Special Issue on Emerging H.264/AVC Video Coding Standard, vol. 17, issue 2, pp. 322-343, Elsevier Press, Apr 2006. [2] Andy C. Yu, Graham Martin, and Heechan Park, “Improved Schemes for Inter-frame Coding in the H.264/AVC Standard,” in Proc. of 12th IEEE Conference on Image Processing (ICIP) 05, vol. 2., pp. 902-905, Genoa, Italy, Sep. 2005. [3] Andy C. Yu, Graham Martin, and Heechan Park, “A Frequency Domain Approach to Intra Mode Selection in H.264/AVC,” in Proc. of 13th European Signal Processing Conference (EUSIPCO) 05, 4pp., Antalya, Turkey, Sep. 2005 [4] Andy C. Yu and Graham Martin, “Advanced Block Size Selection Algorithm for INTER frame Coding in H.264/AVC,” in Proc. of 11th IEEE International Conference on Image Processing (ICIP) 04, vol. 1, pp.95-98, Singapore, Oct 2004. [5] Andy C. Yu, “Efficient Block Size Selection Algorithm for INTER frame Coding in H.264/AVC,” in Proc. of 29th IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) 04, vol. 3, pp. 169-172, Montreal, Canada, May 2004. [6] F. Pan, X. Lin, et al., “Fast mode decision algorithm for Intraprediction in H.264/AVC video coding,” IEEE transaction on Circuits and Systems for Video Technology, pp. 813-823, Jul. 2005. [7] C. Kim, H. Shih, and C. Kuo, “Fast H.264 Intra-prediction mode selection using joint spatial and transform domain features”,Journal of Visual Communication and Image Representation, vol. 17, pp. 291-310, 2006. [8] __, “Information technology – coding of audio visual objects – Part 10: advance video coding,” ISO/IEC 14496-10:2003, Dec. 2003. [9] JVT reference software, JM6.1e, downloaded from http://bs.hhi.de/~suehring/

  39. Q & A

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