Faculty Publications
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Item Sample-based DC prediction strategy for HEVC lossless intra prediction mode(Institute of Electrical and Electronics Engineers Inc., 2017) Kamath, S.S.; Aparna., P.; Antony, A.High-Efficiency Video Coding (HEVC), the state-of-the-art video coding standard by the ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group, is presently being prepared to handle the next generation multi-media services. Lossless mode of HEVC is designed to support a variety of lossless compression applications like medical imaging, preservation of artwork, video analytics, etc. The accuracy of the intra prediction can be improved through the incorporation of sample-based prediction strategies which replace the block-based prediction within HEVC. In this work, we propose a sample-based DC intra prediction strategy to enhance the compression efficiency of the HEVC lossless mode. The detailed experimental analysis demonstrates that the proposed method outperforms the HEVC lossless mode of HM16.12 in terms of bit-rate savings by 1.43% and 0.46% on an average for AI-Main and AI-Main10 configurations respectively, without any increase in run-time. © 2017 IEEE.Item Efficient architectures for planar and DC modes of intra prediction in HEVC(Institute of Electrical and Electronics Engineers Inc., 2020) Lakshm; I Aparna., P.High efficiency video coding (HEVC) handles the ever increasing global video content with better compression efficiency. Complex partition and increased number of angular modes in intra prediction is one of the factors responsible to achieve this but at the expense of complex computations. In this work, we propose two hardware architectures, Parallel Pipelined Architecture (PPA), and Parallel Datapath Architecture (PDA) for the planar and direct current (DC) modes of intra prediction in HEVC. PPA supports a combination of pipelining and parallel schemes, reuses the multipliers to reduce the hardware resources. PDA includes datapath0 for planar mode and datapath1 for DC mode. They function in parallel. They support all the block sizes and implemented on Artix-7 field programmable gate array (FPGA). The implemented results show that PDA uses 20% fewer resources for block size 4, while PPA uses 20%, 46%, and 62% fewer resources for block sizes 8, 16, and 32, respectively. Detailed synthesis results show that PPA and PDA achieve a throughput of 8 pixels/clock cycle and hence can support 4K videos at 30 frames per second. © 2020 IEEE.Item Complexity Analysis of Hardware Architectures for Intra Prediction unit of High Efficiency Video Coding (HEVC)(Institute of Electrical and Electronics Engineers Inc., 2020) Shastri, S.; Lakshm; I Aparna., P.High efficiency Video Coding (HEVC) is the state-of-the-art video coding technique capable of encoding Ultra High Definition (UHD) videos with better compression efficiency and has better reconstruction quality for the same bitrate as compared to its predecessors. Better compression is possible due to its complex partition and prediction methods. These benefits are at the cost of increased computational complexity, which in turn increases resource consumption and processing time. In this work, we design and implement three different architectures, viz: 1) Fully Sequential Architecture (FSA), 2) Semi-parallel Architecture (SPA) and 3) Fully Parallel Architecture (FPA), for the Intra prediction of HEVC on Field Programmable Gate Arrays (FPGA) and discuss the results. These three configurations are tested for the prediction units of sizes 4×4, 8×8 and 16×16. Results show that FSA uses nearly 70% fewer resources than FPA. Also FSA uses 51.73%, 54.33% and 52.2% less resources than SPA for 4×4, 8×8 and 16×16 block sizes, respectively. Also, the FPA implemented for all three pediction unit (PU) sizes is nearly 22 times and 5 times faster than the FSA and SPA, respectively. © 2020 IEEE.Item Gradient-oriented directional predictor for HEVC planar and angular intra prediction modes to enhance lossless compression(Elsevier GmbH journals@elsevier.com, 2018) Shilpa Kamath, S.; Aparna., P.; Antony, A.Recent advancements in the capture and display technologies motivated the ITU-T Video Coding Experts Group and ISO/IEC Moving Picture Experts Group to jointly develop the High-Efficiency Video Coding (HEVC), a state-of-the-art video coding standard for efficient compression. The compression applications that essentially require lossless compression scenarios include medical imaging, video analytics, video surveillance, video streaming etc., where the content reconstruction should be flawless. In the proposed work, we present a gradient-oriented directional prediction (GDP) strategy at the pixel level to enhance the compression efficiency of the conventional block-based planar and angular intra prediction in the HEVC lossless mode. The detailed experimental analysis demonstrates that the proposed method outperforms the lossless mode of HEVC anchor in terms of bit-rate savings by 8.29%, 1.65%, 1.94% and 2.21% for Main-AI, LD, LDP and RA configurations respectively, without impairing the computational complexity. The experimental results also illustrates that the proposed predictor performs superior to the existing state-of-the-art techniques in the literature. © 2018 Elsevier GmbHItem Pixelwise improvised blend of predictors in HEVC lossless mode(Elsevier GmbH, 2020) Shilpa Kamath, S.; Aparna., P.; Antony, A.The commendable work by the two video coding pioneers ISO/IEC and ITU-T, to handle the next-generation of multimedia services has led to the evolution of High Efficiency Video Coding (HEVC) standard. The lossless mode of HEVC is essential when no loss in fidelity is desired to aide most of the real-world applications like video analytics, web collaboration, remote desktop sharing, etc. The proposed work intends to improvise the HEVC intra prediction scheme through the application of the heuristic history-based blend of predefined sub-predictors, while in lossless mode. The prime element of the locally adaptive mechanism is the derivation of the penalizing factors that are imposed on the sub-predictors, based on the neighborhood residuals. The experimental analysis highlights that the proposed method outperforms the lossless mode of HEVC anchor and the prevalent state-of-the-art prediction techniques in terms of savings in bit-rate which is achieved without any increase in run-time. © 2019 Elsevier GmbHItem Performance enhancement of HEVC lossless mode using context-based angular and planar intra predictions(Springer, 2020) Kamath, S.; Aparna., P.; Antony, A.Lossless mode of High-Efficiency Video Coding (HEVC), the state-of-the-art video coding standard, can be used for distortion-free reconstruction of the input data for a wide variety of applications. HEVC relies on the usage of efficient intra prediction strategies to achieve superior compression than its predecessor H.264. A large amount of spatial redundancy exists in almost all video sequences due to coherence, smoothness and the inherent correlation within the neighboring pixels. In this paper, a context-based intra prediction scheme is proposed to minimize this local redundancy by identifying the edges and textures to appropriately modify the prediction strategy at the pixel level, without further increase in the computational complexity. The variability in the sum of absolute differences and local pixel intensity values are chosen to derive the context of the nearby region around the target pixel in the planar and angular intra prediction modes respectively. The experimental results validate the superiority of the proposed method over the HEVC anchor and other state-of-the-art techniques in the literature. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.