By Sudeep Gangavati ID 1000717165 EE5359 Spring 2012, UT Arlington Video Compression Standards : A Comparative Analysis of H.264, Dirac and AVS P2 By Sudeep Gangavati ID 1000717165 EE5359 Spring 2012, UT Arlington

Objective and motivation The goal – to compare H.264/AVC, AVS P2 and Dirac Video quality assessment – MSE, PSNR, SSIM Ever increasing demand for video compression Several different video coding standards have been developed to address the needs efficient video coding for multitude of applications like video streaming, TV broadcasting, 3D TV, Free-viewpoint TV etc. [24]. 1.The main motive behind the project is to compare for performance and analyze video compression standards : H.264/AVC , AVS China Part 2 and Dirac Pro. 2. During the course of the project, several video test sequences will be coded using standard coding software like JM 18.2, Schrodinger ( for Dirac Pro) and AVS Software for AVS video coding. The quality of the video will be assessed for different performance metrics like MSE, PSNR, SSIM, bitrate. 3. Conclusions will be drawn based on the results obtained.

H.264/AVC Features The most widely used video coding standard Fig. 1 Video coding standards evolution [12] 1.By far, H.264 Adv Video Coding std is the most widely used standard for streaming videos, mobile/handheld applications etc. The std was finalized during 2004. H.264 provides the best video compression. 2. There are several codecs that encode/decode videos based on the H.264 standard.The Encoder Structure is similar to MPEG 2

Features Motion compensated coding structure Picture  slices  MBs  subMBs  blocks  pixels. This is shown in Figure 3. Only 4:2:0 chroma format was supported earlier and 4:2:2 , 4:4:4 were added later. This is shown in Figure 2. I , P and B slices Derived slices SI and SP

Fig 2. 4:4:4, 4:2:2, 4:2:0 sampling patterns

Fig 3. H.264 syntax

Profiles and levels Main Profile Baseline Profile Extended Profile High Profile

H.264 Profiles Fig.4 H.264 profiles [1]

H.264 Encoder Fig. 5 Encoder structure for H.264 [2]

H.264 Decoder Fig.6 Decoder structure of H.264 [2]

Intra and Inter Predictions Intra Prediction : Uses spatial prediction to reduce spatial redundancy. 4 X 4 luma – 9 modes 16 X 16 luma – 4 modes 8 X 8 luma- 9 modes

Intra prediction modes for 4X4 luma Fig.7(a) Intra prediction modes [6] The samples above and to the left, labelled A-M in Figure 7 have previously been encoded and reconstructed and are therefore available in the encoder and decoder to form a prediction reference.

Intra Prediction Modes for 16x16 luma Again the previously encoded samples directly above and to the left of the macroblock have been reconstructed and are used for the prediction Fig 7 (b) Intra prediction modes for 16x16 luma [6]

Inter prediction Uses motion estimation and motion compensation (MC). Fig.8 H.264 Inter prediction [5]

De-blocking filter[5] Is used to reduce the blocking artifacts. Since the filter is present in the loop , it prevents the propagation of the blocking artifacts. Fig. 9 Boundaries in a macroblock to be filtered (luma boundaries shown with solid lines and chroma boundaries shown with dotted lines) [1]

AVS China[7] AVS-Audio Video Standard Standardization includes system, audio, video and digital copyright management. Goal – to achieve coding efficiency with reduced complexity.

AVS Parts [3] Fig. 10 AVS China parts [3]

AVS P2 Encoder [7] Fig. 11 AVS part 2 encoder [7]

AVS P2 decoder Fig 11 (a) AVS P2 decoder block diagram [7]

Intra Prediction in AVS[7] Spatial prediction is used in intra coding in AVS part 2. The Intra prediction is based on 8x8 block The intra prediction method is derived from the neighboring pixels in left and top blocks

Intra Prediction contd. Fig.12 (a) Five different modes for intra luminance prediction[16]

Inter prediction [16] Inter prediction in AVS is by motion compensation and motion estimation [16]. As shown in the Figure 12 (b), the macroblock can have 16 x 16, 8 x 16, 16 x 8 or 8 x 8 [16]. Fig 12 (b) Macroblock sizes [16]

Dirac Dirac is a video codec originally developed by BBC This technique is used from web streaming of videos to HD TV applications to storage of content. Dirac can compress any resolution picture The encoder and decoder diagrams are shown in Figure 13 (a) and (b) respectively.

Dirac encoder and decoder : Figure 13 (a) Dirac encoder[8] Figure 13 (b) Dirac decoder[8]

Dirac pro Features Dirac pro supports the following technical aspects [9]: Intra-frame coding only 10 bit 4:2:2 No subsampling Lossless or visually lossless compression Low latency on encode/decode Support for multiple HD image formats and frame rates Low complexity for decoding

Experimental Results Table 1: Parametric values for Dirac video codec Implementation of DIRAC Software 1.02: Video sequence: news_qcif.yuv. Width: 176, Height: 144. Total number of frames: 300 Number of frames used for encoding: 100. Frame rate: 25 FPS. File Size: 3713kB. Quality Factor Compressed File Size Bit rate (kBps) Y-PSNR(dB) Y-MSE Y-SSIM Comrpession Ratio 38 9.573 25.773 187.13 0.79 98:1 5 61 15.571 32.134 39.588 0.95 60:1 10 369 96.301 46.699 1.41 0.98 10:1 15 1278 130.12 51.799 0.743 0.99 2.9:1 Table 1: Parametric values for Dirac video codec

Experimental Results contd. Quality Factor = 0 Quality Factor = 5 Quality Factor = 10 Fig.14 Output of Dirac video codec at different Quality Factors

Table 2. Parametric values of Dirac video codec for foreman_qcif video Video sequence: foreman_qcif.yuv Width: 176; Height: 144. Total number of frames: 300 Number of frames used for encoding: 100. Frame rate: 25 FPS; File Size: 3713kB Quality Factor (QF) Compressed File Size (kB) Bitrate (kBps) Y-PSNR (dB) Y-MSE Y-SSIM Compressio n Ratio 27 8.991 21.5 301.56 0.6875 138:1 5 58 12.675 28.91 110.12 0.8613 64:1 10 581 140.673 43.675 0.827 0.979 6:1 15 1340 170.342 49.556 0.667 0.99 2.7:1 Table 2. Parametric values of Dirac video codec for foreman_qcif video

QF=0 QF=05 QF=10 QF=15 Fig.15 Output of Dirac video codec at different Quality Factors for foreman_qcif video

Implementation of AVS software Video sequence used: news_qcif Implementation of AVS software Video sequence used: news_qcif.yuv Width: 176;Height: 144 Total number of frames: 300; Number of frames used: 100 Frame rate: 25 FPS; File Size: 3713kB QP=0 QP=10 QP=50 Fig.16 Output of AVS video codec at different Quality Factors for news_qcif video Fig.17 Output of AVS video codec at different Quality Factors for foreman _qcif video

Implementation of AVS software Quantization Parameter (QP) Compressed File Size Bit rate (kBps) Y-PSNR(dB) Y-MSE Y-SSIM Comrpession Ratio 980 554.19 54.773 0.2587 0.9997 3:1 10 442 219.12 49.72 0.5525 0.9945 9:1 30 64.0 156.49 38.49 9.23 0.9760 58:1 50 12.0 29.26 27.96 104.13 0.8506 309.7 Table 3. Parametric values of AVS video codec for news_qcif video QP Compressed file size Bitrate Y-PSNR Y-MSE Y-SSIM Compressio n Ratio 1123 478.88 52.658 0.2823 0.998 3:1 10 450 278.9 48.775 0.781 0.9903 8.25:1 30 70 79.66 35.231 13.56 0.867 53:1 50 14 24.5 29.780 146.32 0.776 265:1 Table 4. Parametric values of AVS video codec for foreman_qcif video

Implementation of H.264 software (JM 18.0) Quantization Parameter (QP) Compressed File Size Bit rate (kBps) Y-PSNR(dB) Y-MSE Y-SSIM Comrpession Ratio 279 685.19 60.773 0.21619 0.999 13:1 10 208 410.21 48.545 0.9653 0.9947 17.8:1 30 123 155.62 35.721 17.4211 0.8626 30:1 50 35 29.49 28.736 224.23 0.7644 27.5:1 Table 5. Parametric values of H.264 video codec for news_qcif video Quantization Parameter (QP) Compressed File Size Bit rate (kBps) Y-PSNR(dB) Y-MSE Y-SSIM Comrpession Ratio 379 485.19 62.773 0.21619 0.999 9:1 10 210 340.21 54.67 0.7769 0.9947 18:1 30 98 155.62 34.721 14.4211 0.8626 39:1 50 25 39.49 27.736 236.23 0.6944 27.5:1 Table 6. Parametric values of H.264 video codec for foreman_qcif video

Plots of PSNR (dB) vs. Bitrate (kBps) Fig18. Plot of PSNR vs. Bitrate for different codecs for news_qcif video

Plots of PSNR (dB) vs. Bitrate (kBps) contd.. Fig 19. Plot of PSNR vs. Bitrate for different codecs for foreman_qcif video

Plots of MSE vs. Bitrate Fig 20. Plot of MSE vs. Bitrate for different codecs for news_qcif video

Plots of MSE vs. Bitrate contd.. Fig 21. Plot of MSE vs. Bitrate for different codecs for foreman_qcif video

Plot of SSIM vs. Bitrate Fig 22. Plot of SSIM vs. Bitrate for different codecs for news_qcif video

Plot of SSIM vs. Bitrate Fig 23. Plot of SSIM vs. Bitrate for different codecs for foreman_qcif video

Computational complexity Fig 24. Plot of time taken by each codec at QP=30 and QF=10

Conclusions The plots and tabulations show that with the increase in bitrate, there is an increase in PSNR and SSIM and reduction in the MSE. Therefor from the plots and the tables, it can be concluded that H.264 provides optimum performance with respect to PSNR, MSE and SSIM over AVS part 2 and Dirac. Regarding the computational complexity, H.264 is more complex than the other two standards viz., AVS part 2 and Dirac. This is due to the fact that H.264 supports several prediction modes and has varied macroblock sizes when compared to AVS and Dirac.

References [1] Soon-kak Kwon, A. Tamhankar and K.R. Rao, “Overview of H.264 / MPEG-4 Part 10 (pp.186-216)”, Special issue on “ Emerging H.264/AVC video coding standard”, J. Visual Communication and Image Representation, vol. 17, pp.186-216, April 2006. [2] T. Wiegand, G. Sullivan, G. Bjontegaard and A. Luthra, “Overview of the H.264/AVC video coding standard,” IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, pp.560-576, July 2003. [3] T. Sikora, “Digital video coding standards and their role in video communications”, Signal Processing for Multimedia, J.S. Byrnes (Ed.), IOS press, pp. 225-251, 1999. [4] K. R. Rao, and D. N. Kim, “Current video coding standards: H.264/AVC, Dirac, AVS China and VC-1,” IEEE 42nd Southeastern symposium on system theory (SSST), March 7-9 2010, pp. 1-8, March 2010. [5]Z. Wang and A.C. Bovik, “A universal image quality index”, IEEE Signal Processing Letters,Vol.9, pp. 81-84, March 2002. [6] Iain Richardson, “ The H.264 advanced video coding standard”, Second Edition,Wiley, 2010 [7] L. Yu et al, “An Overview of AVS-Video: tools, performance and complexity”, Visual Communications and Image Processing, Proc. of SPIE, vol. 5960, pp. 679-690, July 2005. [8] “ The Dirac web page” :http://www.bbc.co.uk/rd/projects/dirac/intro.shtml [9] “Dirac Codec Wiki Page ” at http://en.wikipedia.org/wiki/Dirac(codec) [10]“Dirac Pro web page” at http://www.bbc.co.uk/rd/projects/dirac/diracpro.shtml [11] “Video on the web “ a http://etill.net/projects/dirac_theora_evaluation/ [12] J.Lou “Advanced video codec optimization techniques”, Doctoral Dissertation, Electrical Engineering Department, University of Washington, August 2009

References [13] H.264 AVC JM Software : http://iphome.hhi.de/suehring/tml/  [14] H.264 decoder: http://www.adalta.it/Pages/407/266881_266881.jpg  [15] W. Gao et al, “AVS - The Chinese next-generation video coding Standard” NAB, Las Vegas, 2004.  [16] X. Wang et al., “Performance comparison of AVS and H.264/AVC video coding standards” J. Comput. Sci. & Technol., vol.21, No.3, pp.310-314, May 2006.  [17] AVS China part 2 video software, password protected : ftp://124.207.250.92/  [18] S. Swaminathan and K.R. Rao, “Multiplexing and demultiplexing of AVS CHINA video with AAC audio,” TELSIKS 2011, Nis, Serbia, 5-8 Oct. 2011. [19] Dirac Pro Software : http://diracvideo.org/download/  [20] M. Tun, K.K. Loo and J. Cosmas, “Semi-hierarchical motion estimation for the Dirac video codec,” 2008 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, pp.1–6, March 31-April 2, 2008. [21] T. Davies, “The Dirac Algorithm”: http://dirac.sourceforge.net/documentation/algorithm/, 2008. [22] Dirac video codec – A programmer's guide: http://dirac.sourceforge.net/documentation/code/programmers_guide/toc.htm [23] A. Ravi and K.R. Rao, “Performance analysis and comparison of the Dirac video codec with H.264 / MPEG-4 Part 10 AVC,”IJWMIP, vol.4, pp.635-654, No.4, 2011. [24] Proceedings of the IEEE Special issue on Frontiers of Audiovisual Communications, vol. 100, No.4, April 2012