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Addressing transmission errors in underwater acoustic channels is a key challenge for the real-time video communication between an autonomous underwater vehicle and a surface station. In this paper, we propose an error-resilient video compression technique based on hybrid multiple descriptions and redundant pictures to overcome impact of packet loss in underwater acoustic transmission. Video sequences...
Researchers are extensively investigating motion estimation for H.265 (HEVC), the newest video coding standard for wired and wireless environments. Reducing the complexity of encoding in mobile applications is essentially required for smooth transmission as well as storage. The principal contributor towards this complexity is the motion estimation component of the encoder. Parallel processing of motion...
In the paper, we describe the extensions of the 3D-HEVC compression technology aimed at improved compression efficiency for multiview sequences acquired from arbitrarily located cameras. Our proposal refines the inter-view prediction by replacing the horizontal shifts with the true mapping in the 3D space. This implies changes in several coding tools, which we describe in details. The paper also reports...
In hardware video encoders, the throughput of the entropy coding stage can limit the support of high-quality and high-resolution videos. This paper presents an FPGA-oriented optimization method which increases the clock frequency of the probability modeling stage of the multi-symbol Context Adaptive Binary Arithmetic Coder (CABAC). The method leverages the unary code to represent probability states...
Encoders based on the High Efficiency Video Coding (HEVC) standard consider an input sequence as a succession of slices grouped in Structures of Pictures (SOP). The SOP used while encoding specifies many parameters, such as the coding order of frames, or the reference frames used during inter-prediction. Reference encoders typically make use of a fixed SOP structure of a given size, which is periodically...
The new video coding standard HEVC (High Efficiency Video Coding) offers the desired compression performance in the era of HDTV and UHDTV, as it achieves nearly 50% bit rate saving compared to H.264/AVC. To leverage the involved computational overhead, HEVC offers three parallelization potentials namely: wavefront parallelization, tile-based and slice-based. In this paper we study slice-based parallelization...
Low-bitrate video compression is a challenging task, particularly with the increasing complexity of video sequences. Re-shaping video data before its compression with modern hybrid encoders has provided interesting results in the low and ultra-low bit rate domains. In this work, we propose a novel saliency guided preprocessing approach, which combines adaptive re-sampling and background texture removal,...
This paper proposes an enhanced motion compensated prediction algorithm for hybrid video coding. The algorithm is built upon the concept of applying adaptive enhancement filtering at the motion compensation stage. For luma, a high-pass filter is applied to the motion compensated prediction signal to recover distorted high-frequency information. For chroma, cross-plane filters are applied to enhance...
Many approaches have been proposed to support lossless coding within video coding standards that are primarily designed for lossy coding. The simplest approach is to just skip transform and quantization and directly entropy code the prediction residual, which is used in HEVC version 1. However, this simple approach is inefficient for compression. More efficient approaches include processing the residual...
In this paper, we present a novel perceptually-based optimization for the improvement of stereoscopic video coding efficiency. The main idea of this proposed scheme is to adaptively adjust the quantization parameter by taking into account the Human Visual System perceptual characteristics. For this, a saliency map is generated from both views and then segmented into salient and non-salient regions...
We propose an algorithm that accomplishes transform-coded, spatiotemporal, pel-recursive video compression. Traditional pel-recursive coders obtain sophisticated spatio-temporal predictions for the current pixel based on previously decoded data. The resulting per-pixel prediction errors are encoded independently so that the decoder can use previously-encoded pixels in the prediction of the current...
In intra video coding, intra frames are predicted with intra prediction and the prediction residual signal is encoded. In many transform-based video coding systems, intra prediction residuals are encoded with transforms. For example, the Discrete Cosine Transform (DCT) and the Asymmetric Discrete Sine Transform (ADST) are used for intra prediction residuals in many coding systems. In the recent work,...
This paper introduces a novel class of transforms, called graph-based separable transforms (GBSTs), based on two line graphs with optimized weights. For the optimal GBST construction, we formulate a graph learning problem to design two separate line graphs using row-wise and column-wise residual block statistics, respectively. We also analyze the optimality of resulting separable transforms for both...
The demands for high quality multimedia contents and the advent of the Ultra High Definition (UHD) resolution have motivated the development of the High Efficiency Video Coding (HEVC) standard, which outperforms prior standards by up to 50% in terms of coding efficiency. This improvement, however, involves higher computational complexity in the encoder side, making it essential for realtime encoders...
Fisheye cameras have become extremely popular in applications where the goal is to capture large fields of view with only one camera. However, the wide-angle fisheye imagery has special characteristics that may not be very well suited for modern video codecs that employ block-based translational motion model. This model fails to describe complex deformable motion which is often present in fisheye...
In the context of motion estimation (ME) for video coding, the rate-constrained successive elimination algorithm (RC-SEA) safely eliminates candidate motion vectors while preserving the optimal candidate chosen by the block matching algorithm (BMA). This paper describes a technique for reusing ME information from rectangular to square prediction units in order to reduce the search area without altering...
We introduce a constant luminance HDR video coding pipeline, which converts the source video to linear Y u'v' color space and applies a dedicated chromaticity transformation before encoding. This reduces perceivable color artifacts without modifying the core codec itself. We validate our approach by a user study that shows a significant improvement in perceived color quality at high compression rates...
The efficiency improvements achieved by new video coding standards come at the cost of a huge increase in the encoder computational complexity. Paradoxically, such increasing complexity is commonly addressed by methods that have an adverse effect on coding efficiency. In this work, we propose a method to reduce the complexity of HEVC Hadamard ME, without compromising coding efficiency. Our method...
In the absence of a commercial High Dynamic Range (HDR) distribution pipeline, two-layer backward-compatible HDR video coding is a viable solution for the imminent transition from Low Dynamic Range (LDR) to HDR content transmission. However, the performance of a two-layer coding solution is governed by the extension layer coding performance. In this paper, we propose an improved two-layer backward-compatible...
Intra-frame prediction in the High Efficiency Video Coding (HEVC) standard can be empirically improved by applying sets of recursive two-dimensional filters to the predicted values. However, this approach does not allow (or complicates significantly) the parallel computation of pixel predictions. In this work we analyze why the recursive filters are effective, and use the results to derive sets of...
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