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Domain Rate Control Algorithm for HEVC. Bin Li, Houqian Li, Li Li , and Jinlei Zhang IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL.23, NO.9, SEPTEMBER 2014. Overview. Introduction -Domain R-D Analysis Rate Control Based on - Domain Model Experimental Results Conclusion. Introduction.
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Domain Rate Control Algorithm for HEVC Bin Li, Houqian Li, Li Li, and Jinlei Zhang IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL.23, NO.9, SEPTEMBER 2014
Overview • Introduction • -Domain R-D Analysis • Rate Control Based on -Domain Model • Experimental Results • Conclusion
Introduction • Rate control plays an important role in video applications, especially in real time communication applications. • MPEG-2 : TM5 • MPEG-4 : VM8 • H.264 : based on the R-D model in VM8 [4] • H.265 : • R - Q model in HM8 • R - model in HM10.0.0
Introduction • Two steps of rate control : • 1. Allocate proper number of bits to each coding level (GOP, picture, basic unit, etc.) • 2. Achieve the pre-allocated bits for each level. E.g., with other parameter fixed(mode, motion, etc.), larger QP generally leads to smaller bit-rate.
Introduction Step1 Step2
Introduction • How to design rate control algorithm? • Consider Rate-Distortion performance. • Rate control problem can thus be formulated as : = Or =
Introduction • Two class of rate control algorithm before -domain RC : • 1.Build the relationship between Q and R ->Q-domain • 2.Build the relationship between and R ->-domain • Q-domain : [16] • Approvement : [18][19][20][21] • -domain : [10][11] • Approvement : [22][23]
Introduction • Both assume there exists a close relationship between R and Q. However, with video coding schemes becoming more flexible, Q is no longer the critical factor on rate control. • To overcome the disadvantages mentioned above, authors find a more robust correspondence between and R.
Reference • [4] K.-P. Lim, G. Sullivan, and T. Wiegand, Text Description of Joint Model Reference Encoding Methods and Decoding Concealment Methods, document Rec. JVT-N046, Hong Kong, China, Jan. 2005. • [10] Z. He, Y. K. Kim, and S. K. Mitra, “Low-delay rate control for DCT video coding via ρ-domain source modeling,” IEEE Trans. Circuits Syst. Video Technol., vol. 11, no. 8, pp. 928–940, Aug. 2001. • [11] M. Liu, Y. Guo, H. Li, and C. W. Chen, “Low-complexity rate control based on ρ-domain model for scalable video coding,” in Proc. 17th IEEE Int. Conf. Image Process. (ICIP), Sep. 2010, pp. 1277–1280. • [16] S. Ma, W. Gao, and Y. Lu, “Rate-distortion analysis for H.264/AVC video coding and its application to rate control,” IEEE Trans. Circuits Syst. Video Technol., vol. 15, no. 12, pp. 1533–1544, Dec. 2005. • [18] Y. Liu, Z. G. Li, and Y. C. Soh, “A novel rate control scheme for low delay video communication of H.264/AVC standard,” IEEE Trans. Circuits Syst. Video Technol., vol. 17, no. 1, pp. 68–78, Jan. 2007. • [19] H. Wang and S. Kwong, “Rate-distortion optimization of rate control for H.264 with adaptive initial quantization parameter determination,” IEEE Trans. Circuits Syst. Video Technol., vol. 18, no. 1, pp. 140–144, Jan. 2008. • [20] S. Hu, H. Wang, and S. Kwong, “Adaptive quantization-parameter clip scheme for smooth quality in H.264/AVC,” IEEE Trans. Image Process., vol. 21, no. 4, pp. 1911–1919, Apr. 2012. • [21] Z. He and S. K. Mitra, “Optimum bit allocation and accurate rate control for video coding via ρ-domain source modeling,” IEEE Trans. Circuits Syst. Video Technol., vol. 12, no. 10, pp. 840–849, Oct. 2002. • [22] Y. Pitrey, Y. Serrand, M. Babel, and O. Deforges, “Rho-domain for low-complexity rate control on MPEG-4 scalable video coding,” in Proc. 10th IEEE Int. Symp. Multimedia, Dec. 2008, pp. 89–96. • [23] Y. Pitrey, M. Babel, and O. Deforges, “One-pass bitrate control for MPEG-4 scalable video coding using ρ-domain,” in Proc. IEEE Int. Symp. Broadband Multimedia Syst. Broadcast. (BMSB), May 2009, pp. 1–5.
Overview • Introduction • -Domain R-D Analysis • Rate Control Based on -Domain Model • Experimental Results • Conclusion
-Domain R-D Analysis • Several types of R-D model have been proposed to characterize the relationship between R and D. • Exponential function [31]: • Hyperbolic function [32][33]:
-Domain R-D Analysis • is the slope of R-D curve, which can be expressed as : • So we can determine R in another form :
Benefits of -Domain Model • One-to-one correspondence between R and . • No inter-dependency between determination and RDO process. • Adjustingis equivalent to adjusting optimization target. • Adjusting can be much more precise than adjusting QP(integer).
Overview • Introduction • -Domain R-D Analysis • Rate Control Based on -Domain Model • Experimental Results • Conclusion
Rate Control Algorithm • Bit allocation • For the First Picture • For GOP Level • For Picture Level • For Basic Unit Level • Achieve the target bit-rate for a specific unit (Rate Control Coding)
Bit Allocation • 1.For first picture : 6 times of the average bits per picture • 2.For GOP Level : Ideally, should be , But 40 If , then If , then
Bit Allocation • For picture level : • All pictures with same is one possible choice • Hierarchical bit allocation is another choice
Bit Allocation • For basic unit(CTU in HEVC) level : Similar to picture level bit allocation
Rate Control Coding • Determine the value and the other coding parameter used for encoding. • determination and updating : • RDO coding :
Rate Control Coding • Determine the value and the other coding parameter used for encoding. • determination and updating : Different level may have different parameter Target bit-rate corresponding to different level
Rate Control Coding • Determine the value and the other coding parameter used for encoding. • RDO coding : Originally, all the parameter can be determined by exhaustive RDO search. (Including mode, motion, etc.) 13.7122 4.2005
Overview • Introduction • -Domain R-D Analysis • Rate Control Based on -Domain Model • Experimental Results • Conclusion
Experiment Design • Three rate control algorithm in experiments. • RC in HM-8.0 (R-Q model) • Proposed RC (R- model, no hierarchical) • Proposed RC (R- model, hierarchical)
Overview • Introduction • -Domain R-D Analysis • Rate Control Based on -Domain Model • Experimental Results • Conclusion
Conclusion • The difference between actual and target bitrate with proposed method is rather small and has a very high control accuracy. • Both the R-D performance and subjective quality of proposed method are better than rate control in HM-8.0. • While hierarchical bit allocation is disabled, the proposed method can keep almost constant bit for every picture.