1. Study and Optimization of the Deblocking Filter in H
Study and Optimization of the Deblocking Filter in H.265 and its Advantages over H.264
By:
Valay Shah
Under the guidance of:
Dr. K. R. Rao

2. EE-5359 : Project Proposal Presentation
HEVC Overview
HEVC – a buzz word in compression standards
Also known as H.265
50% bit rate reduction compared to H.264 (same picture quality)
Price – more complex video coding algorithm with computationally more expensive tools[2]
HEVC test codec – HM (HEVC test Model)
2/21/2013
EE-5359 : Project Proposal Presentation

3. EE-5359 : Project Proposal Presentation
What’s Different?
Picture partitioning
A Coding Tree Block (CTB) of upto 64×64 spatial dimension in HEVC against 16×16 Macro-Block (MB) in H.264
Minimum size of Coding Unit (CU) in HEVC is 8×8 versus 4×4 in H.264
In-loop deblocking filtering
Sample Adaptive Offset (SAO) filtering
Challenges:
HEVC takes more time (approx. 40%) and hence more power consumption [2]
2/21/2013
EE-5359 : Project Proposal Presentation

4. Deblocking Filter (DBF)
Focusing on – Deblocking filter to reduce the processing time
In-loop deblocking filtering in HEVC:
Similar to H.264, operated within inter-prediction loop
Simplified design in regard to its decision making, hence makes it viable for parallel processing
In HEVC the processing order of the deblocking filter is [1]:
Horizontal filtering for vertical edges for the entire picture first
Followed by vertical filtering for horizontal edges
2/21/2013
EE-5359 : Project Proposal Presentation

5. EE-5359 : Project Proposal Presentation
Parallel Deblocking
Salient Features [2]:
- Larger deblocking removes data dependency between the edges in one direction (H.264 uses 4×4 deblocking filter size versus 8×8 used by HEVC)
- Hence, the vertical and horizontal filtering could be parallelized fully
2/21/2013
EE-5359 : Project Proposal Presentation

6. EE-5359 : Project Proposal Presentation
HEVC DBF Procedure[2]
Advantages:
Allows parallel deblocking
Disadvantages:
Increases the processing time since some data needs to be re-fetched
2/21/2013
EE-5359 : Project Proposal Presentation

7. Modified DBF Procedure[2]
The principle of performing vertical filtering first followed by the horizontal filtering is kept intact
The difference lies in selection of the blocks as shown in the figure on left
2/21/2013
EE-5359 : Project Proposal Presentation

8. EE-5359 : Project Proposal Presentation
Proposed Work
Try to implement modified architecture in HEVC software code to get the performance enhancement
Implement a low complexity offsets perceptual optimization for deblocking filtering [3]
Optimize the skipping mode technique in order to decrease edge processing thereby reducing the power consumption
Compare the HEVC performance with H.264
2/21/2013
EE-5359 : Project Proposal Presentation

9. EE-5359 : Project Proposal Presentation
Expected Results
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EE-5359 : Project Proposal Presentation

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References
[1] G. J. Sullivan et al, “Overview of the High Efficiency Video Coding (HEVC) Standard”, IEEE Transactions on Circuits and Systems for Video Technology, vol. 22, no. 12, pp , Dec [2] M. Li et al, “De-blocking Filter Design for HEVC and H.264/AVC/AVC”, PCM 2012, LNCS 7674, pp. 273–284, [3] M. Naccari et al, “Low Complexity Deblocking Filter Perceptual Optimization For The HEVC Codec”, 18th IEEE International Conference on Image Processing, pp , [4] A. Norkin et al, “HEVC Deblocking Filter”, IEEE Transactions on Circuits and Systems for Video Technology, Vol. 22, No. 12, pp , Dec [5] A. J. Honrubia, J. L. Martínez and P. Cuenca, “HEVC: A Review, Trends and Challenges”, Instituto de Investigación en Informática de Albacete, Spain. [6] T. Wiegand et al, “High Efficiency Video Coding (HEVC) Standarization”, IEEE Transactions on Circuits and Systems for Video Technology, Dec [7] C. Man-Yau and S. Wan-Chi, “Computationally-Scalable Motion Estimation Algorithm for H.264/AVC Video Coding”, IEEE Transactions on Consumer Electronics, vol. 56, pp , 2010.
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EE-5359 : Project Proposal Presentation

11. EE-5359 : Project Proposal Presentation
References-contd.
[8] R. Jianfeng, N. Kehtarnavaz, and M. Budagavi, “Computationally Efficient Mode Selection in H.264/AVC Video Coding, IEEE Transactions on Consumer Electronics, vol. 54, pp , [9] Dr. K. R. Rao, “High Efficiency Video Coding”, Chapter 5 – soon to be published. [10] P. List et al, “Adaptive deblocking filter”, IEEE Transactions on Circuits and Systems for Video Technology, vol. 13, pp , [11] K. Xu and C. S. Choy, “A Five-Stage Pipeline, 204 Cycles/MB, Single-Port SRAM-Based Deblocking Filter for H.264/AVC”, IEEE Transactions on Circuits and Systems, vol. 18(3), pp. 363–374, [12] F. Tobajas et al, “An Efficient Double-Filter Hardware Architecture for H.264/AVC De-blocking Filtering”, IEEE Transactions on Consumer Electronics, Vol. 54(1), Feb [13] Y. C. Lin et al, “A Two-Result-Per-Cycle De-Blocking Filter Architecture for QFHD H.264/AVC Decoder”, IEEE Transactions on VLSI Systems, vol. 17(6), June [14] D. Zhou et al, “A 48 Cycles/MB H.264/AVC De-blocking Filter Architecture for Ultra High Definition Applications”, IEICE Transactions Fundamentals E92-A (12), Dec [15] JM software download for H.264/AVC: [16] HM codec download for H.265:
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EE-5359 : Project Proposal Presentation

12. EE-5359 : Project Proposal Presentation
Implementation Steps
Enable/Disable Deblocking Filter
LoopFilterDisable parameter – under Deblock Filter – alone would not do the job of disabling the deblocking filter
Have to use combination of following deblocking filter parameters:
DeblockingFilterControlPresent
LoopFilterDisable
LoopFilterBetaOffset_div2
LoopFilterTcOffset_div2
2/21/2013
EE-5359 : Project Proposal Presentation

13. Results – Total Encoding Time
# of Frames
Seq. 1
Seq. 2
Seq. 3
Seq. 4 1
57.19
56.878
61.418
62.119
120.05
16.426
16.63 2
32.62
32.682 5
80.902
81.229 10
161.94
100  - -
Total time taken in sec for encoding where columns in yellow (i.e.: 2, 4, 6 & 8) denotes results where deblocking filter was disabled whereas columns in green (i.e.: 3, 5, 7 & 9) denotes results where the deblocking filter was enabled and its parameters were optimized.
2/21/2013
EE-5359 : Project Proposal Presentation

14. EE-5359 : Project Proposal Presentation
Results – Bit-Rate
# of Frames
Seq. 1
Seq. 2
Seq. 3
Seq. 4 1
5816
5825.2
7960.8
1934.4 2
5801.6
5810.4 5 10
5714
100  - -  -
Bit-rate in kbps for encoding where columns in yellow (i.e.: 2, 4, 6 & 8) denotes results where deblocking filter was disabled whereas columns in green (i.e.: 3, 5, 7 & 9) denotes results where the deblocking filter was enabled and its parameters were optimized.
2/21/2013
EE-5359 : Project Proposal Presentation

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Results – PSNR
# of Frames
Seq. 1
Seq. 2
Seq. 3
Seq. 4 1
57.19
56.878
61.418
62.119
120.05
16.426
16.63 2
32.62
32.682 5
80.902
81.229 10
161.94
100  - -
PSNR in dB of the encoded image where columns in yellow (i.e.: 2, 4, 6 & 8) denotes results where deblocking filter was disabled whereas columns in green (i.e.: 3, 5, 7 & 9) denotes results where the deblocking filter was enabled and its parameters were optimized.
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EE-5359 : Project Proposal Presentation

16. EE-5359 : Project Proposal Presentation
Conclusions
It is apparent from the results that the bit-rate have increased by optimizing the deblocking filter parameters.
Hence, there are two benefits of applying the deblocking filter:
(i) it will help remove the blocking artifacts from the reconstructed image and
(ii) it will help increase the bit-rate of the signal
2/21/2013
EE-5359 : Project Proposal Presentation

17. EE-5359 : Project Proposal Presentation
Next Steps
To include the Quantization Parameter (QP) to see how does it affect the performance since it affects Beta and tC (deblocking parameters)
To vary all the deblocking parameters to get the best results in terms of PSNR, total encoding time and bit-rate
2/21/2013
EE-5359 : Project Proposal Presentation