3DTV a), a) Dual Codec Based Joint Bit Rate Control Scheme for Terrestrial Stereoscopic 3DTV Broadcast Yongjun Chang a) and Munchurl Kim a) 3 3 (3DTV). ATSC 18Mbps. 3D, 2DTV,. 3DTV. - (quadratic rate-quantization model).. 3DTV, / 2.02%, 77.6%, 74.%. Abstract Following the proliferation of three-dimensional video contents and displays, many terrestrial broadcasting companies have been preparing for stereoscopic 3DTV service. In terrestrial stereoscopic broadcast, it is a difficult task to code and transmit two video sequences while sustaining as high quality as 2DTV broadcast due to the limited bandwidth defined by the existing digital TV standards such as ATSC. Thus, a terrestrial 3DTV broadcasting with a heterogeneous video codec system, where the left image and right images are based on and, respectively, is considered in order to achieve both high quality broadcasting service and compatibility for the existing 2DTV viewers. Without significant change in the current terrestrial broadcasting systems, we propose a joint rate control scheme for stereoscopic 3DTV service based on the heterogeneous dual codec systems. The proposed joint rate control scheme applies to the encoder a quadratic rate-quantization model which is adopted in the. Then the controller is designed for the sum of the left and right bitstreams to meet the bandwidth requirement of broadcasting standards while the sum of image distortions is minimized by adjusting quantization parameter obtained from the proposed optimization scheme. Besides, we consider a condition on maintaining quality difference between the left and right images around a desired level in the optimization in order to mitigate negative effects on human visual system. Experimental results demonstrate that the proposed bit rate control scheme outperforms the rate control method where each video coding standard uses its own bit rate control algorithm independently in terms of the increase in by 2.02%, the decrease in the average absolute quality difference by 77.6% and the reduction in the variance of the quality difference by 74.%. Keyword : stereoscopic 3DTV broadcast, joint bit rate control, quadratic rate-quantization model, linear distortionquantization model, heterogeneous dual codec system
1. 3DTV Fig. 1. Tentative terrestrial 3DTV broadcasting system. 3D 3DTV. 3DTV ATSC (Advanced Television Sys- tems Committee), 18Mbps [1]. 2D TV (High Definition TV). H.264/ AVC /, 2DTV. 3DTV, 1, a) Korea Advanced Institute of Science and Technology : (mkim@ee.kaist.ac.kr) IT (NIPA-2011-(C1090-1111-0003)). (20101221),(201133),(2011316) [2].,. H.264/ AVC 2 - (quadratic rate- quantization model) [3,4] (joint bit rate control scheme)., 3 / [5], [6]., [5,6] / / ( ).,. 2
36 db 35 34 33 32 31 0 10 20 30 40 50 (a) Foreman CIF sequence 45 44 43 42 db 41 40 (b) Mother&Daughter CIF sequence 2., / (-: 500kbps, : 250kbps; IPPP, 50 ) Fig. 2. Quality difference between the left and right videos (Target bitrate-: 500 kbps, : 250 kbps; IPPP, 50 frames) 500 kbps 250 kbps CIF Foreman Mother & Daughter P. 2 Foreman 1.08~3.56 db, Mother & Daughter 0.33~3.63 db /, /. /. -,, 1/4,,,, 4x4 DCT, [7]. 250 kbps 500 kbps
., /,, / 2, / /.. GOP (Group Of Pictures), 2 -. MAD MAD [4]. 2 - [3]. (1). 1. 2D. -,, 1/4,, 4x4 DCT, [7]...,, [8]. MPEG-4 2 - (Mean Absolute Difference: MAD) (1) q ( mquant, Qstep),, a, b. a, b MAD,. (1). 2. 3D 2 - (1) (1) (D) (q) (2). min (2) (2) R 2 -. 3DTV (3),, /.
min (3) (3) i, MSE (Mean Squared Error), i, i=1, i=2. (3), (3) (1) 2 - - ( ) (4). min (4), (4). / k (4) (5). min - (1). (5) (5),. (5) MAD [3,4]. (5) MSE,. 3. 3D GOP,,,. 3. GOP GOP. GOP I. P [4]., I GOP GOP P, GOP,. (5) R T, (5).
3. Fig. 3. Proposed joint bit rate control algorithm. GOP. (MSE), (MAD). (5) a i, b i, a i (i=1,2) [3].. MSE (Peak Signal to Noise Ratio), (, ). / 2D. 1. 1. 1 2:1., 2 2. 1. Table 1. Experimental condition () () TM5 JM16.0 Main Baseline 4 40 GOP IPPP 50 GOP 50 k 0 2D CIF (352x288) Stereoscopic 480x270 2D 720p (1280x720) Foreman (750 Kbps) Mother&Daughter (750 Kbps) Car (750 Kbps) Horse (1.5 Mbps) Night (6 Mbps)
3DTV P () 4 5. 4 (a), (b) 2 (a), (b) 3 /. 4 (c)~(e) /. 2, /,. 2 (6)~(9). (6) (7) / 59~87%. / (8). 50~91%. 5 /, -1.85~0.83%. 2.,, Table 2. Average video quality, average quality difference, standard deviation of quality difference, and relative improvement (8) Δ (%) Foreman 33.44 34.59 3.4 제안방법 기존방법 기존방법 (9) Mother&Daughter 40.79 41.88 2.7 Car 35.87 36.61 2.1 i (i=1,2) n, N. (6) / (5). 2 0.1~3.4%. (5) (7), 1 0 (7). 2 Horse 33.44 33.49 0.1 Night 32.85 33.45 1.8 Foreman 2.08 0.33-84.1 Mother&Daughter 1.20 0.49-59.2 Car 0.75 0.21-72.0 Horse 2.64 0. -85.6 Night 2.09 0.27-87.1 Foreman 0.18 0.09-50.0 Mother&Daughter 1.80 0.34-81.1 Car 0.48 0.04-91.7 Horse 0.58 0.15-74.1 Night 0.20 0.05-75.0
36 db 35 34 33 32 31 (a) Foreman CIF sequence 41 40 db 36 35 34 33 32 31 (c) Car 480x270 sequence 36 35 49 48 47 46 45 44 db 43 42 41 40 (b) Mother & Daughter CIF sequence 36 35 34 33 db 32 31 30 29 28 27 26 (d) Horse 480x270 sequence 34 db 33 32 31 30 4. / Fig. 4. Quality difference with the proposed joint bit rate scheme 29 (e) Night 720p sequence
35000 30000 25000 20000 발생비트율 Dual Codec 200000 150000 발생비트율 Dual Codec 15000 100000 10000 5000 50000 0 0 (a) Foreman CIF sequence (Relative error: 0.13%) (b) Mother & Daughter CIF sequence (Relative error: 0.63%) 발생비트율 발생비트율 35000 30000 Dual Codec 120000 100000 Dual Codec 25000 80000 20000 60000 15000 10000 40000 5000 20000 0 0 (c) Car 480x270 sequence (Relative error: -1.85%) (d) Horse 480x270 sequence (Relative error: 0.83%) 발생비트율 350000 300000 250000 Dual Codec 200000 150000 100000 50000 0 (e) Night 720p sequence (Relative error: -0.33%) 5. / Fig. 5. Generated encoding bit rates with the proposed joint bit rate scheme and relative errors from target bit rates
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