為了減少在高效率視訊編碼標準中編碼器的計算複雜度，本論文提出一個快速編碼單元深度決策演算法，根據分析可得知當前區塊與鄰近區塊或是不同畫面相同位置的區塊有很高的深度相關性，因此本論文可以利用空間域與時域關係中已編碼區塊的深度資訊去產生當前區塊預測的深度搜尋範圍，包含預測的最大深度與預測的最小深度，其中我們分為幾種情況，分別是當前區塊的深度小於預測的最小深度、當前區塊的深度落在預測的最小深度與最大深度之間與當前區塊的深度大於預測的最大深度時，針對當前區塊在不同的情況下會使用不同的演算法判斷，以達到最佳的預測效果與編碼速度。接著我們分析在高效率視訊編碼標準中合併模式的特性，並根據此分析結果實現在最新的HEVC版本中，由於這兩個演算法不衝突，因此最後會將此兩方法合併起來使用，使加速效果大大提升。另外我們進一步的利用編碼區塊旗標和量化參數的資訊分析對編碼器造成的影響，並用來確保整體的編碼品質。模擬數據證明在HM14.0版本中可節省約50.18%的計算複雜度，伴隨著上升1.3%的畫面品質損失比例。

To reduce the computational complexity of encoder in High Efficiency Video Coding (HEVC), this thesis proposes a fast coding unit (CU) depth decision algorithm, from analyze that shows there is a high depth correlation in current block, neighbor blocks or co-located block. Thus we can utilize the depth information of spatio-temporal encoded block to generate a depth search range (DSR) with maximum and minimum depths prediction. We divide three cases include depth of current block is smaller than minimum depth prediction, among minimum depth and maximum depth prediction and bigger than maximum depth prediction. Aforementioned cases will execute different algorithms for achieving best coding effect and time. Next we analyze the characteristic of Merge mode in HEVC and accordingly implement the last HEVC version. All proposed methods are compatible to each other and we combine aforementioned algorithms into the encoder to get maximum performance. Furthermore We further make using of coded block flag (CBF) as well as information of quantization parameter (QP) to analyze that for impacting of encoder and also apply to speed up with coding quality assurance. The proposed algorithm can reduce unnecessary CU depth prediction to accelerate the encoding time. Simulation results show that up to 50.18% computational complexity can be saved, with only up to 1.3% BD-rate increasing in Low-Delay configuration of HM14.0.

[1]T. Wiegand, G. J. Sullivan, G. Bjontegaard and A. Luthra, “Overview of the H.264/AVC Video Coding Standard,” IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, no. 7, pp.560-576, July 2003.
[2]T. Wiegand, J. R. Ohm, G. J. Sullivan, W. J. Han, R. Joshi, T. K. Tan and K. Ugur, “Special section on the joint call for proposals on High Efficiency Video Coding (HEVC) standardization,” IEEE Circuits and Systems for Video Technology, pp.1661-1666, 2010.
[3]JCT-VC, “Coding tree pruning based CU early termination,” JCTVC-F092, 6th Meeting, Torino, IT, 2011.
[4]JCT-VC, “Early termination of CU encoding to reduce HEVC complexity,” JCTVC-F045, 6th Meeting, Torino, IT, 2011.
[5]JCT-VC, “Early SKIP Detection for HEVC,” JCTVC- G543, 7th Meeting, Geneva, 2011.
[6]C. Zhou, F. Zhou and Y. Chen, “Spatio-temporal correlation-based fast coding unit depth decision for high efficiency video coding,” Journal of Electronic Imaging, vol. 22, issue. 4, pp. 1-14, Oct. 2013.
[7]J. H. Lee, C. S. Park and B. G. Kim, “Fast Coding Algorithm Based on Adaptive Coding Depth Range Selection for HEVC,” 2012 IEEE International Conference on Consumer Electronics, Sept. 2012, pp. 31-33.
[8]L. Shen, Z. Zhang and Z. Liu, “Adaptive inter-mode decision for HEVC jointly utilizing inter-level and spatio-temporal correlations,” IEEE Transactions on Circuits and Systems for Video Technology, pp. 1-27, March 2014.
[9]H. L. Tan, F. Liu, Y. H. Tan and C. Yeo, “On fast coding tree block and mode decision for high-Efficiency Video Coding (HEVC),” 2012 IEEE International Conference on Acoustics, Speech and Signal Processing, March 2012, pp. 825-828.
[10]W. J. Hsu and H. M. Hang, “Fast coding unit decision algorithm for HEVC,” IEEE Signal and Information Processing Association Annual Summit and Conference (APSIPA), Nov. 2013, pp.1-5.
[11]J. Leng, L. Sun, T. Ikenaga and S. Sakaida, “Content Based Hierarchical Fast Coding Unit Decision Algorithm for HEVC,” IEEE Multimedia and Signal Processing (CMSP), May 2011, pp.56-59.
[12]L. Shen, Z. Liu, X. Zhang and W. Zhao, “An Effective CU Size Decision Method for HEVC Encoders,” IEEE Multimedia, pp.465-470, Feb. 2013.
[13]JCT-VC, “High Efficiency Video Coding (HEVC) Test Model 14 (HM14) Encoder Description,” JCTVC-P1002, 16th Meeting, San José, US, 2014.
[14]JCT-VC, “Common test conditions and software reference configurations,” JCTVC-G1200, 7th JCTVE meeting, Geneva, 2011.
[15]JCT-VC, “Test sequence material (AHG16),” JCTVC-P0016, 16th Meeting, San José, US, 2014.
[16]G. Bjontegaard, “Calculation of average PSNR difference between RD curves,” VCEG-M33, 13th VCEG meeting, Austin, 2011.
[17]Y. Zhang, H. Wang, Z. Li, “Fast Coding Unit Depth Decision Algorithm for Interframe Coding in HEVC,” Data Compression Conference (DCC), March 2013, pp. 43-53.
[18]N. Purnachand, L. N. Alves and A. Navarro, “Fast Motion Estimation Algorithm for HEVC,” 2012 IEEE International Conference on Consumer Electronics - Berlin, Sept. 2012, pp. 34-37.
[19]A. Glantz, M. Tok, A. Krutz and T. Sikora, “A block-adaptive skip mode for inter prediction based on parametric motion models,” 2011 18th IEEE International Conference on Image Processing (ICIP), Sept. 2011, pp. 1201-1204.
[20]H. Lv, R. Wang, X. Xie, H. Jia and W. Gao, “A comparison of fractional-pel interpolation filters in HEVC and H.264/AVC,” 2012 IEEE Visual Communications and Image Processing (VCIP), Nov. 2012, pp. 1-6.
[21]J. Xiong, H. Li, Q. Wu and F. Meng, “A Fast HEVC Inter CU Selection Method Based on Pyramid Motion Divergence,” IEEE Transactions on Multimedia, Feb. 2014, pp. 559-564.
[22]I. K. Kim, J. Min, T. Lee, W. J. Han and J. H. Park, “Block Partitioning Structure in the HEVC Standard,” IEEE Transactions on Circuits and Systems for Video Technology, pp. 1697-1706, Dec. 2012.
[23]M. Li, K. Chono and S. Goto, “Low-complexity merge candidate decision for fast HEVC encoding,” 2013 IEEE International Conference on Multimedia and Expo Workshops (ICMEW), July 2013, pp. 1-6.
[24]J. L. Lin, Y. W. Chen, Y. W. Huang and S. M. Lei, “Motion Vector Coding in the HEVC Standard,” IEEE Journal of Selected Topics in Signal Processing, pp. 957-968, Dec. 2013.
[25]H. S. Kim, J. H. Lee, C. K. Kim and B. G. Kim, “Zoom Motion Estimation Using Block-Based Fast Local Area Scaling,” IEEE Transactions on Circuits and Systems for Video Technology, pp. 1280-1291, Sept. 2012.
[26]G. J. Sullivan, J. Ohm, W. J. Han and T. Wiegand, “Overview of the High Efficiency Video Coding (HEVC) Standard,” IEEE Transactions on Circuits and Systems for Video Technology, pp. 1649-1668, Dec. 2012.
[27]Y. H. Tan, C. Yeo, H. L. Tan and Z. Li, “On residual quad-tree coding in HEVC,” 2011 IEEE 13th International Workshop on Multimedia Signal Processing (MMSP), Oct. 2011, pp. 1-4.
[28]C. E. Rhee, K. Lee, T. S. Kim and H. J. Lee, “A survey of fast mode decision algorithms for inter-prediction and their applications to high efficiency video coding,” IEEE Transactions on Consumer Electronics, Nov. 2012, pp. 1375-1383.
[29]G. Tian and S. Goto, “An optimization scheme for quadtree-structured prediction and residual encoding in HEVC,” 2012 IEEE Asia Pacific Conference on Circuits and Systems (APCCAS), pp. 547-550, Dec. 2012.
[30]Z. Guo, D. Zhou and S. Goto, “An optimized MC interpolation architecture for HEVC,” 2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pp. 1117-1120, March 2012.
[31]S. Matsuo, S. Takamura and H. Jozawa, “LCU-based adaptive interpolation filter,” 2012 Picture Coding Symposium (PCS), May 2012, pp. 393-399.
[32]J. Shu, R. Wu, and F. Fan, “An improved motion estimation diamond search algorithm based on H264” 2011 International Conference on Computational Problem-Solving (ICCP), Oct. 2011, pp. 21-23.
[33]H. M. Wong, O. C. Au, A. Chang, S. K. Yip and C. W. Ho, “Fast mode decision and motion estimation for H.264 (FMDME)” 2006 IEEE International Symposium on Circuits and Systems, May 2006.
[34]Y. C. Lin, T. Fink and E. Bellers, “Fast Mode Decision for H.264 Based on Rate-Distortion Cost Estimation” IEEE International Conference on Acoustics, Speech and Signal Processing, April 2007, pp. 1137-1140.
[35]C. S. Kannangara, I. E. G. Richardson, M. Bystrom, J. R. Solera, Y. Zhao, A. MacLennan and R. Cooney, “Low-complexity skip prediction for H.264 through Lagrangian cost estimation” IEEE Transactions on Circuits and Systems for Video Technology, pp. 202-208, Feb. 2006.
[36]K. Asai, T. Murakami, S. Yamagishi, A. Minezawa, Y. Itani, K. Sugimoto, S. I. Sekiguchi, Y. Yamada, and Y. Kato, “New Video Coding Scheme Optimized for High-Resolution Video Sources” IEEE Journal of Selected Topics in Signal Processing, pp. 1290-1297, Nov. 2011.
[37]A. Saha, M. Kallol, J. Mukherjee and S. Sural, “SKIP Prediction for Fast Rate Distortion Optimization in H.264” IEEE Transactions on Consumer Electronics, pp. 1153-1160, Aug. 2007.
[38]Z. Pan, Y. Zhang, S. Kwong, X. Wang and L. Xu, “Early termination for TZSearch in HEVC Motion Estimation” 2013 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), May 2013, pp. 1389-1393.
[39]J. H. Lee, C. S. Park, B. G. Kim, D. S. Jun, S. H. Jung and J. S. Choi, “Novel fast PU decision algorithm for the HEVC video standard” 2013 20th IEEE International Conference on Image Processing (ICIP), Sept. 2013, pp. 1982-1985.
[40]D. Wei, O. C. Au, S. Li, S. Lin and R. Zou, “Fast sub-pixel motion estimation with simplified modeling in HEVC” 2012 IEEE International Symposium on Circuits and Systems (ISCAS), May 2012, pp. 1560-1563.