186 research outputs found

    Distributed video coding for wireless video sensor networks: a review of the state-of-the-art architectures

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    Distributed video coding (DVC) is a relatively new video coding architecture originated from two fundamental theorems namely, Slepian–Wolf and Wyner–Ziv. Recent research developments have made DVC attractive for applications in the emerging domain of wireless video sensor networks (WVSNs). This paper reviews the state-of-the-art DVC architectures with a focus on understanding their opportunities and gaps in addressing the operational requirements and application needs of WVSNs

    Study and simulation of low rate video coding schemes

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    The semiannual report is included. Topics covered include communication, information science, data compression, remote sensing, color mapped images, robust coding scheme for packet video, recursively indexed differential pulse code modulation, image compression technique for use on token ring networks, and joint source/channel coder design

    Distributed Video Coding for Multiview and Video-plus-depth Coding

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    CAL Dataflow Components for an MPEG RVC AVC Baseline Encoder

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    In this paper, an efficient H.264/AVC baseline encoder, described in RVC-CAL actor language, is introduced. The main aim of the paper is twofold: a) to demonstrate the flexibility and ease that is provided by RVC-CAL, which allows for efficient implementation of the presented encoder, and b) to shed light on the advantages that can be brought into the RVC framework by including such encoding tools. The main modules of the designed encoder include: Inter Frame Prediction (Motion Estimation/Compensation), Intra Frame Prediction, and Entropy Coding. Descriptions of the designed modules, accompanied with RVC-CAL design issues are provided. A comparison between different development approaches is also provided. The obtained results show that specifying complex video codecs (e.g. H.264/AVC encoder) using RVC-CAL followed by automatic translation into HDL, which is achievable by the tools that support the standard, results in more efficient HW implementation compared to the traditional HW design flow. A discussion that explains the reasons behind such results concludes the pape

    Mode decision for the H.264/AVC video coding standard

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    H.264/AVC video coding standard gives us a very promising future for the field of video broadcasting and communication because of its high coding efficiency compared with other older video coding standards. However, high coding efficiency also carries high computational complexity. Fast motion estimation and fast mode decision are two very useful techniques which can significantly reduce computational complexity. This thesis focuses on the field of fast mode decision. The goal of this thesis is that for very similar RD performance compared with H.264/AVC video coding standard, we aim to find new fast mode decision techniques which can afford significant time savings. [Continues.

    Efficient Motion Estimation and Mode Decision Algorithms for Advanced Video Coding

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    H.264/AVC video compression standard achieved significant improvements in coding efficiency, but the computational complexity of the H.264/AVC encoder is drastically high. The main complexity of encoder comes from variable block size motion estimation (ME) and rate-distortion optimized (RDO) mode decision methods. This dissertation proposes three different methods to reduce computation of motion estimation. Firstly, the computation of each distortion measure is reduced by proposing a novel two step edge based partial distortion search (TS-EPDS) algorithm. In this algorithm, the entire macroblock is divided into different sub-blocks and the calculation order of partial distortion is determined based on the edge strength of the sub-blocks. Secondly, we have developed an early termination algorithm that features an adaptive threshold based on the statistical characteristics of rate-distortion (RD) cost regarding current block and previously processed blocks and modes. Thirdly, this dissertation presents a novel adaptive search area selection method by utilizing the information of the previously computed motion vector differences (MVDs). In H.264/AVC intra coding, DC mode is used to predict regions with no unified direction and the predicted pixel values are same and thus smooth varying regions are not well de-correlated. This dissertation proposes an improved DC prediction (IDCP) mode based on the distance between the predicted and reference pixels. On the other hand, using the nine prediction modes in intra 4x4 and 8x8 block units needs a lot of overhead bits. In order to reduce the number of overhead bits, an intra mode bit rate reduction method is suggested. This dissertation also proposes an enhanced algorithm to estimate the most probable mode (MPM) of each block. The MPM is derived from the prediction mode direction of neighboring blocks which have different weights according to their positions. This dissertation also suggests a fast enhanced cost function for mode decision of intra encoder. The enhanced cost function uses sum of absolute Hadamard-transformed differences (SATD) and mean absolute deviation of the residual block to estimate distortion part of the cost function. A threshold based large coefficients count is also used for estimating the bit-rate part

    Compression of dynamic polygonal meshes with constant and variable connectivity

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    This work was supported by the projects 20-02154S and 17-07690S of the Czech Science Foundation and SGS-2019-016 of the Czech Ministry of Education.Polygonal mesh sequences with variable connectivity are incredibly versatile dynamic surface representations as they allow a surface to change topology or details to suddenly appear or disappear. This, however, comes at the cost of large storage size. Current compression methods inefficiently exploit the temporal coherence of general data because the correspondences between two subsequent frames might not be bijective. We study the current state of the art including the special class of mesh sequences for which connectivity is static. We also focus on the state of the art of a related field of dynamic point cloud sequences. Further, we point out parts of the compression pipeline with the possibility of improvement. We present the progress we have already made in designing a temporal model capturing the temporal coherence of the sequence, and point out to directions for a future research
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