BIN LI, HOUQIAN LI, LI LI, AND JINLEI ZHANG IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL.23, NO.9, SEPTEMBER 2014 1.

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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

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Overview Introduction

-Domain R-D Analysis

Rate Control Based on -Domain Model

Experimental Results

Conclusion

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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

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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.

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Introduction

Step1 Step2

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Introduction How to design rate control algorithm?

◦ Consider Rate-Distortion performance.

Rate control problem can thus be formulated as :

=

Or

=

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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]

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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.

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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.

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Overview Introduction

-Domain R-D Analysis

Rate Control Based on -Domain Model

Experimental Results

Conclusion

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-Domain R-D Analysis Several types of R-D model have been proposed to characterize the relationship between R and D.

1. Exponential function [31]:

2. Hyperbolic function [32][33]:

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-Domain R-D Analysis is the slope of R-D curve, which can be expressed as :

So we can determine R in another form :

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Benefits of -Domain Model

1. One-to-one correspondence between R and .

2. No inter-dependency between determination and RDO process.

3. Adjusting is equivalent to adjusting optimization target.

4. Adjusting can be much more precise than adjusting QP(integer).

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Overview Introduction

-Domain R-D Analysis

Rate Control Based on -Domain Model

Experimental Results

Conclusion

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Rate Control Algorithm1. Bit allocation

◦ For the First Picture◦ For GOP Level◦ For Picture Level◦ For Basic Unit Level

2. Achieve the target bit-rate for a specific unit (Rate Control Coding)

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Bit Allocation 1.For first picture : 6 times of the average bits per picture

2.For GOP Level : Ideally, should be , But

If , then

If , then

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Bit Allocation For picture level :

1. All pictures with same is one possible choice2. Hierarchical bit allocation is another choice

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Bit Allocation For basic unit(CTU in HEVC) level : Similar to picture level bit allocation

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Rate Control Coding Determine the value and the other coding parameter used for encoding.

1. determination and updating :2. RDO coding :

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Rate Control Coding Determine the value and the other coding parameter used for encoding.

1. determination and updating :

Different level may have different parameter

Target bit-rate corresponding to different level

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Rate Control Coding Determine the value and the other coding parameter used for encoding.

2. RDO coding : Originally, all the parameter can be determined by exhaustive RDO search. (Including mode, motion, etc.)

4.2005 13.7122

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Overview Introduction

-Domain R-D Analysis

Rate Control Based on -Domain Model

Experimental Results

Conclusion

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Experiment Design Three rate control algorithm in experiments.

1. RC in HM-8.0 (R-Q model)2. Proposed RC (R- model, no hierarchical)3. Proposed RC (R- model, hierarchical)

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Experimental Results

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Experimental Results

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Experimental Results

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Experimental Results

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Experimental Results

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Experimental Results

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Experimental Results

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Overview Introduction

-Domain R-D Analysis

Rate Control Based on -Domain Model

Experimental Results

Conclusion

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Conclusion1. The difference between actual and target bitrate with proposed

method is rather small and has a very high control accuracy.

2. Both the R-D performance and subjective quality of proposed method are better than rate control in HM-8.0.

3. While hierarchical bit allocation is disabled, the proposed method can keep almost constant bit for every picture.