Improved ρ-domain rate control with accurate header size estimation 24. May, 211 Fan Zhang fan.zhang@tum.de Eckehard Steinbach eckehard.steinbach@tum.de
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.97-982, 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. 1237-1249, Nov. 28 2
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
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% Foreman(CIF)@512kbps 7% 6% Percentage 5% 4% 3% motion info. type info. CBP info. QP info. 2% 1% % 5 1 15 2 25 Frame Number 4
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 45 7 4 35 6 size (bits) 3 25 2 size (bits) 5 4 3 15 1 5 total header bits motion bits 2 1 total header bits motion bits 1 2 3 4 5 6 7 N nzmve +ω*n MV 2 4 6 8 1 12 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.517-529, May 27 5
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) 45 4 35 3 25 2 15 1 5 5 1 15 2 25 3 N nzmvd +ω*n zmvd total header bits motion bits size (bits) 7 6 5 4 3 2 1 1 2 3 4 5 6 N nzmvd +ω*n zmvd total header bits motion bits 6
Rate model for CBP information in inter-mbs Model in [Shen7] 25 Foreman(CIF) high rate 1 Foreman(CIF) low rate 9 2 8 7 cbp bits 15 1 5.1.2.3.4 1 ρ cbp bits 6 5 4 3 2 1.2.4.6.8.1 1 ρ 7
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 18 16 16 14 cbp bits 14 12 1 8 6 cbp bits 12 1 8 6 4 4 2 2 5 1 15 2 25 3 N nzmb +ω*n zmb 5 1 15 2 25 3 N nzmb +ω*n zmb 8
Two-Stage Rate Control Algorithm 9
Experimental Results Sequence Level (deviation from target bit rate) 1
Experimental Results Frame level fluctuation 41 Foreman(QCIF)@192k 4 39 frame size 38 37 36 35 34 1 2 3 4 5 6 7 8 9 1 frame number orig MVHE proposed 11
Experimental Results MB level QP fluctuation 3 Foreman(QCIF) F5 29 Foreman(QCIF) F1 29 28 qp 28 27 26 25 orig MVHE proposed qp 27 26 25 orig MVHE proposed 24 2 4 6 8 1 MB index 24 2 4 6 8 1 MB index 12
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
Thank you for your attention 14
Motivation X264 encoded Foreman/M&D size (bits) 5 x 14 4 3 2 Foreman(CIF) high rate size (bits) 12 1 8 6 4 Foreman(CIF) low rate High Rate: QP:25-33 1 total bits texture bits 1 2 3 4 1 ρ 2 total bits texture bits.2.4.6.8 1 1 ρ Low Rate: QP:34-45 1.5 2 x 14 M&D(CIF) high rate 6 5 4 M&D(CIF) low rate size (bits) 1 size (bits) 3 2.5 total bits texture bits 1 total bits texture bits.5 1 1.5 1 ρ.1.2.3.4 1 ρ 15
Rate model for CBP information in inter-mbs Performance of the proposed CBP rate model Seq. Bitrate (kbps) R 2 Value M&D (CIF) 384.9347 Foreman (CIF) 512.9725 Football (CIF) 64.9749 Carphone (CIF) 384.974 16
Rate model for motion information in inter-mbs Performance comparison Seq. Bitrate (kbps) Kwon7 R 2 Value Proposed M&D (CIF) 384.5742.9219 Foreman (CIF) 512.7373.9767 Football (CIF) 64.7119.973 Carphone (CIF) 384.78.9772 17