Improved ρ-domain rate control with accurate header size estimation

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1 Improved ρ-domain rate control with accurate header size estimation 24. May, 211 Fan Zhang Eckehard Steinbach

2 Motivation p-domain rate control ([He2],[He8]) p-domain rate control in H.264 Increased amount of header data [He2] Z.He and S.K.Mitra, A linear source model and a unified rate control algorithm for DCT video coding, IEEE Trans. Circuits Syst. Video Technol., vol. 12, pp , Nov.22 [He8] Z.He and D.O.Wu, Linear rate control and optimum statistical multiplexing for H.264 video broadcast, IEEE Trans., Multimedia, vol. 1, no. 7, pp , Nov. 28 2

3 Outline Motivation Proposed Rate Control Algorithm Header information in H.264 Rate model for motion information in inter-mb Rate model for CBP information in inter-mb Two-Stage Rate Control Algorithm Experimental Results Bitrate accuracy Frame size fluctuation QP variation in a frame Conclusion & Future Work 3

4 Header Data in H.264 Header Size Estimation (HSE) in H.264 Header Information in H.264 HSE for intra macroblocks HSE for inter macroblocks (motion information & CBP) 8% 7% 6% Percentage 5% 4% 3% motion info. type info. CBP info. QP info. 2% 1% % Frame Number 4

5 Rate model for motion information in inter-mbs Linear model in [Shen7] 5 R hdr, p ( N + N ) = γ ω nzmve M&D(CIF)@384kbps MV 8 Foreman(CIF)@512kbps size (bits) size (bits) total header bits motion bits 2 1 total header bits motion bits N nzmve +ω*n MV N nzmve +ω*n MV [Shen7] M.Y.Shen D.K.Kwon and C.C.J.Kuo, Rate control for H.264 video with enhanced rate and distortion models, IEEE Trans. Circuits Syst. Video Technol., vol. 17, no, 5, pp , May 27 5

6 Rate model for motion information in inter-mbs Proposed rate model for motion information R mot, p mot ( N + N ) = γ ω nzmvde mot zmvde 5 M&D(CIF)@384kbps 8 Foreman(CIF)@512kbps size (bits) N nzmvd +ω*n zmvd total header bits motion bits size (bits) N nzmvd +ω*n zmvd total header bits motion bits 6

7 Rate model for CBP information in inter-mbs Model in [Shen7] 25 Foreman(CIF) high rate 1 Foreman(CIF) low rate cbp bits ρ cbp bits ρ 7

8 Rate model for CBP information in inter-mbs Proposed rate model for CBP information R cbp, p cbp ( N + N ) = γ ω nzmb cbp zmb 2 M&D(CIF)@384kbps 18 Foreman(CIF)@512kbps cbp bits cbp bits N nzmb +ω*n zmb N nzmb +ω*n zmb 8

9 Two-Stage Rate Control Algorithm 9

10 Experimental Results Sequence Level (deviation from target bit rate) 1

11 Experimental Results Frame level fluctuation frame size frame number orig MVHE proposed 11

12 Experimental Results MB level QP fluctuation 3 Foreman(QCIF) F5 29 Foreman(QCIF) F qp orig MVHE proposed qp orig MVHE proposed MB index MB index 12

13 Conclusion Rate models for header information of H.264 Bits for Motion Information Bits for Coded Block Pattern (CBP) Two-stage ρ-domain rate control algorithm Better rate control accuracy through header estimation Smaller frame size fluctuation in a sequence Smaller QP variation within a frame 13

14 Thank you for your attention 14

15 Motivation X264 encoded Foreman/M&D size (bits) 5 x Foreman(CIF) high rate size (bits) Foreman(CIF) low rate High Rate: QP: total bits texture bits ρ 2 total bits texture bits ρ Low Rate: QP: x 14 M&D(CIF) high rate M&D(CIF) low rate size (bits) 1 size (bits) total bits texture bits 1 total bits texture bits ρ ρ 15

16 Rate model for CBP information in inter-mbs Performance of the proposed CBP rate model Seq. Bitrate (kbps) R 2 Value M&D (CIF) Foreman (CIF) Football (CIF) Carphone (CIF)

17 Rate model for motion information in inter-mbs Performance comparison Seq. Bitrate (kbps) Kwon7 R 2 Value Proposed M&D (CIF) Foreman (CIF) Football (CIF) Carphone (CIF)

Video Coding Basics. Yao Wang Polytechnic University, Brooklyn, NY11201 yao@vision.poly.edu

Video Coding Basics. Yao Wang Polytechnic University, Brooklyn, NY11201 yao@vision.poly.edu Video Coding Basics Yao Wang Polytechnic University, Brooklyn, NY11201 yao@vision.poly.edu Outline Motivation for video coding Basic ideas in video coding Block diagram of a typical video codec Different