1. FAST MODE DECISION ALGORITHM FOR INTRA PREDICTION IN HEVC
INTERIM REPORT
Lanka Naga Venkata Sai Surya Teja
Student ID
Mail ID
Date 04/24/2014
UNDER THE GUIDANCE OF
Dr. K. R. Rao

2. PROPOSAL
To improve the coding efficiency of intra frame coding, up to 34 intra prediction modes are defined in High Efficiency Video Coding (HEVC) [1]
The best mode among these pre-defined intra prediction modes is selected by rate-distortion optimization (RDO) for each block
This project proposes a new method to reduce the candidates in RDO process, as it will be time-consuming if all directions are tested in the RDO process when compared with the default method of intra prediction in HM 13.0.
Also analysis of PSNR, BD- PSNR, BD- Bitrate can be done by comparing with the default encoding scheme in HM 13.0 [5].

3. INTRODUCTION
HEVC standard [2] provides a highly flexible hierarchy of unit representation which consists of three block concepts: coding unit (CU), prediction unit (PU), and transform unit (TU).
This separation of the block structure is helpful for each unit of optimization.
CU is a macroblock-like unit of region splitting which is always square and its size can be from 8x8 luma samples up to the largest coding units (LCUs).
The PU is used only for the CU which is the leaf node in the Quadtree structure and the size of two PUs are 2Nx2N and NxN.
The third block concept transform unit size cannot exceed that of the CU.

4. BLOCK DIAGRAM OF HEVC ENCODER[15]

5. BLOCK DIAGRAM OF H.264 ENCODER[20]

6. BLOCK DIAGRAM OF HEVC DECODER[15]

7. Since encoder needs to exhaust all the combinations of CU, PU and TU to find the optimal solutions, it is very time-consuming
The encoder will not tolerate it if all the directions are employed in the rate-distortion optimization process
To reduce the computational complexity of the encoder, a fast intra mode decision [4] was adopted in HM13.0 [5]

8. CODING TREE ALGORITHM

9. OVERVIEW OF INTRA PREDICTION
In H.264, intra prediction [6][7][8][9] is based on spatial extrapolation of samples from previously decoded image blocks, followed by integer discrete cosine transform (DCT) [10] based coding
HEVC utilizes the same principle, but further extends it to efficiently represent wider range of textural and structural information in images
HEVC contains several elements improving the efficiency of intra prediction over earlier solutions

10. HEVC INTRA PREDICTION MODES [7]

11. H.264 INTRA PREDICTION MODES[21]

12. METHOD PROPOSED FOR FAST MODE DECISON ALGORITHM FOR INTRA PREDICTION
The fast intra prediction consists of three steps:
Hadamard Transformed Coefficients Of Residual Signal[13]
Progressive Mode Search[13]
Early RDOQ Termination[13]

13. TEST SEQUENCES
[1] BQSquare_416x240_60

14. [2] BQMall_ 832x480_60

15. [3] KristenAndSara_1280x720_60

16. EXPERIMENTAL RESULTS of BQMall_832x480_60
Analysis of results for unmodified method with number of frames 10
Analysis of results for modified method with number of frames 10 QP
BITRATE
(kbps)
PSNR
(avg) db
ENCODING TIME
(sec) 24
41.137 28 32 34 QP
BITRATE
(kbps)
PSNR
(avg) db
ENCODING TIME
(sec) 24 28 32 34
98.271

17. EXPERIMENTAL RESULTS of BQMall_832x480_60
Analysis of results for unmodified method with number of frames 30
Analysis of results for modified method with number of frames 30 QP
BITRATE
(kbps)
PSNR
(avg) db
ENCODING TIME
(sec) 24 28 32 34 QP
BITRATE
(kbps)
PSNR
(avg) db
ENCODING TIME
(sec) 24 28 32
312.44 34

18. Encoding Time Vs QP
For number of frames 10
For number of frames 30

19. PSNR (avg) vs Bitrate
For number of frames 10
For number of frames 30

20. CONCLUSION
For the HM13.0 with fast mode decision algorithm method compared to unmodified HM13.0,
dB loss in the PSNR
11-15 kbps increase in the bitrate
20-28 % reduction in encoding time
WQVGA – SD sequences of 10 frames and 30 frames each were tested from QPs 24, 28,32,34. Visual quality was maintained.

21. Future Work
BD-PSNR and BD-bitrate can be compared for default method and proposed method
Also proposes a new method to reduce the candidates in RDO process, as it will be time-consuming if all directions are tested in the RDO process.

22. ACRONYMS BD- Bitrate - Bjøntegaard Delta Bitrate
BD- PSNR -  Bjøntegaard Delta Peak Signal-to-Noise Ratio
CU - Coding Unit
DCT - Discrete Cosine Transform
DST Discrete Sine Transform
HEVC - High Efficiency Video Coding
JCT- VC- Joint Collaborative Team on Video Coding
LCU - Largest Coding Unit
MPM - Most Probable Mode
PSNR - Peak Signal-to-Noise Ratio
PU Prediction Unit
QP Quantization Parameter
RDOQ - Rate Distortion Optimization Quantization
RDO - Rate- Distortion Optimization
RMD - Rough Mode Decision
SSIM - Structural Similarity Index
TU Transform Unit

23. REFERENCES
[1] G.J. Sullivan et al, Overview of the high efficiency video coding (HEVC) standard‖, IEEE Trans. circuits and systems for video technology, vol. 22, no.12, pp – 1668, Dec 2012.
[2] JCT-VC, “WD1: Working Draft 1 of High-Efficiency Video Coding”, JCTVC-C403, JCT-VC Meeting, Guangzhou, October 2010.
[3] Coding tree structure -
[4] Y. Piao et al, “Encoder improvement of unified intra prediction,” JCTVC-C207, Guangzhou, October
[5] Software for HEVC -
[6] T.L. Silva et al, ”HEVC intra coding acceleration based on tree inter-level mode correlation”, SPA 2013 Sep.2013, Poznan, Poland
[7] H. Zhang and Z. Ma, ”Fast intra prediction for high efficiency video coding ”, Pacific Rim Conf. on Multimedia, PCM2012, Singapore, Dec
[8] M. Zhang et al, ”An adaptive fast intra mode decision in HEVC ”, IEEE ICIP 2012, pp , Orlando, FL, Sept.- Oct

24. [9] Y. Kim et al, “A fast intra-prediction method in HEVC using rate-distortion estimation based on Hadamard transform”, ETRI Journal, vol.35, #2, pp , Apr
[10 ]A. Saxena and F. Fernanades, “Mode dependent DCT/DST for intra prediction in block based image/video coding”, IEEE ICIP, pp , Sept
[11] M. Khan et al, “An adaptive complexity reduction scheme with fast prediction unit decision for HEVC Intra encoding”, IEEE ICIP, pp , Sept
[12] P. Mehta, “Complexity reduction for intra mode selection in HEVC using OpenMP”, course website: Section: previous projects, Sub section: Projects (Spring 2014).
[13] S. Vasudevan, “Fast intra prediction and fast residual quadtree encoding implementation in HEVC”, course website: Section: previous projects, Sub section: Projects (Spring 2014).
[14] K.R.Rao , D. N. Kim and J.J. Hwang ,” Video coding standards: AVS China, H.264/MPEG-4 Part10, HEVC, VP6, DIRAC and VC-1"´, Springer, 2014.

25. [15] G.Sullivan et al, “Standard Extensions of the High Efficiency Video Coding (HEVC) Standard” Journal of Special Topics in Signal Processing, vol.7, No. 6, pp , Dec 2013.
[16] Test Sequences: ftp://ftp.kw.bbc.co.uk/hevc/hm-11.0-anchors/testsequences/
[17] F. Bossen et al, "HM Software Manual", JCT-VC of ITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11, AHG chairs, January 2014
[18] B. Bross et al, “High Efficiency Video Coding (HEVC) Text Specification Draft 10”, Document JCTVC- L1003, ITU-T/ISO/IEC Joint Collaborative Team on Video Coding (JCT-VC), Mar available on
[19] JVT Draft ITU-T recommendation and final draft international standard of joint video specification (ITU-T Rec. H.264-ISO/IEC AVC), March 2003, JVT-G050 available on

26. [22] Special issue on emerging research and standards in next generation video coding, IEEE Transactions on Circuits and Systems for Video Technology (CSVT), vol.22, pp , Dec
[23] Special issue on emerging research and standards in next generation video coding, IEEE Transactions on Circuits and Systems for Video Technology (CSVT), vol.23, pp , Dec
[24] IEEE Journal of Selected Topics in Signal Processing, Vol. 7, pp , Dec