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This paper addresses high performance depth coding in 3D video by making good use of its coded texture video counterpart. The relationship between the depth and its associated texture video in terms of coding mode and motion vector is carefully examined. Our statistical study suggests that the skip-coding mode and its associated motion vectors in the coded texture can be shared for depth coding by saving bit rate at the cost of little increase of distortion, which subsequently results in a nonsequential coding of the depth map. In this sense, coding/prediction of a block can be performed using the skip-coded blocks below and right, which are not available in the conventional sequential coding, thus producing the so-called omnidirectional blocks predicted in the intra-coding by making the best use of (at most) four neighboring blocks. Moreover, in view of the depth-texture structure similarity, a depth-texture cooperative clustering-based prediction method is proposed for cluster-based depth prediction in the intra-coding, which exploits the structure similarity for the current coding block and its neighboring pixels around the block. On the other hand, some large prediction errors may be present for the depth-texture misaligned pixels, which may greatly compromise the coding performance. To deal with these large residuals induced by the depth-texture misalignment, a simple yet effective detection and rectification approach is incorporated in the proposed depth coding scheme. Experimental results show that our proposed depth coding scheme achieves superior rate-distortion performance compared with other relevant coding methods. [ABSTRACT FROM PUBLISHER]

This paper describes transform coefficient coding in the draft international standard of High Efficiency Video Coding (HEVC) specification and the driving motivations behind its design. Transform coefficient coding in HEVC encompasses the scanning patterns and coding methods for the last significant coefficient, significance map, coefficient levels, and sign data. Special attention is paid to the new methods of last significant coefficient coding, multilevel significance maps, high-throughput binarization, and sign data hiding. Experimental results are provided to evaluate the performance of transform coefficient coding in HEVC. [ABSTRACT FROM PUBLISHER]

A concept of a quadtree based nonsquare block coding structure is presented in this paper for the emerging High Efficiency Video Coding standard, which includes a quadtree based asymmetric motion partitioning scheme and a nonsquare quadtree transform (NSQT) algorithm. Nonsquare motion partitioning in inter frame coding provides the possibility of getting more accurate prediction results by splitting one coding block into two nonsquare prediction blocks. Contrary to the traditional symmetric motion partitions (SMP), asymmetric motion partitions (AMP) are proposed to improve the coding efficiency, especially for the coding blocks with irregular object boundaries. NSQT is designed for nonsquare prediction blocks (SMP and AMP), which combines square and nonsquare transform blocks in a unified transform structure. It exploits the directional characteristic of an image block to improve the transform efficiency. The combination of nonsquare partitions and NSQT provides high coding flexibility and low implementation cost for both encoder and decoder design. Simulation results show that about 0.9%–2.8% bit-rate saving can be achieved in terms of different configurations, and subjective quality can also be improved. [ABSTRACT FROM PUBLISHER]

The lossless coding mode of the High Efficiency Video Coding (HEVC) main profile that bypasses transform, quantization, and in-loop filters is described. Compared to the HEVC nonlossless coding mode with the smallest quantization parameter value (i.e., 0 for 8-b video and -12 for 10-b video), the HEVC lossless coding mode provides perfect fidelity and an average bit-rate reduction of 3.2%–13.2%. It also significantly outperforms the existing lossless compression solutions, such as JPEG2000 and JPEG-LS for images as well as 7-Zip and WinRAR for data archiving. To further improve the coding efficiency of the HEVC lossless mode, a sample-based angular intra prediction (SAP) method is presented. The SAP employs the same prediction mode signaling method and the sample interpolation method as the HEVC block-based angular prediction, but uses adjacent neighbors for better intra prediction accuracy and performs prediction sample by sample. The experimental results reveal that the SAP provides an additional bit-rate reduction of 1.8%–11.8% on top of the HEVC lossless coding mode. [ABSTRACT FROM PUBLISHER]

Motion compensated prediction plays a vital role in achieving enormous video compression efficiency in advanced video coding standards. Most practical motion compensated prediction techniques implicitly assume pure translational motions in the video contents for effective operation. Some attempts aiming at more general motion models are usually too complex requiring parameter estimation in practical implementation. In this paper, zoom motion compensation is investigated to extend the assumed model to support both zoom and translation motions. To accomplish practical complexity, a novel and efficient subsampled block-matching zoom motion estimation technique is proposed which makes use of the interpolated reference frames for subpixel motion estimation in a conventional hybrid video coding structure. Specially designed subsampling patterns in block matching are used to realize the translation and zoom motion estimation and compensation. No zoom parameters estimation and additional frame buffers are required in the encoder implementation. The complexity of the decoder is similar to the conventional hybrid video codec that supports subpixel motion compensation. The overall increase in memory requirement and computational complexity is moderate. Experimental results show that the new technique can achieve up to 9.89% bitrate reduction using KTA2.2r1 reference software implementation. [ABSTRACT FROM PUBLISHER]

In dual frame motion compensation (DFMC), one short-term reference frame and one long-term reference frame (LTR) are utilized for motion compensation. The performance of DFMC is heavily influenced by the jump updating parameter and bit allocation for the reference frames. In this paper, first the rate-distortion performance analysis of motion compensated prediction in DFMC is presented. Based on this analysis, an adaptive jump updating DFMC (JU-DFMC) with optimal LTR selection and bit allocation is proposed. Subsequently, an error resilient JU-DFMC is further presented based on the error propagation analysis of the proposed adaptive JU-DFMC. The experimental results show that the proposed adaptive JU-DFMC achieves better performance over the existing JU-DFMC schemes and the normal DFMC scheme, in which the temporally most recently decoded two frames are used as the references. The performance of the adaptive JU-DFMC is significantly improved for video transmission over noisy channels when the specified error resilience functionality is introduced. [ABSTRACT FROM AUTHOR]

Effectively coding multiview visual content is an indispensable research topic because multiview image and video that provide greatly enhanced viewing experiences often contain huge amounts of data. Generally, conventional hybrid predictive-coding methodologies are adopted to address the compression by exploiting the temporal and interviewpoint redundancy existing in a multiview image or video sequences. However, their key yet time-consuming component, motion estimation (ME), is usually not efficient in interviewpoint prediction or disparity estimation (DE), because interviewpoint disparity is completely different from temporal motion existing in the conventional video. Targeting a generic fast DE framework for interviewpoint prediction, we propose a novel DE technique in this paper to accelerate the disparity search by employing epipolar geometry. Theoretical analysis, optimal disparity vector distribution histograms, and experimental results show that the proposed epipolar geometry-based DE can greatly reduce search region and effectively track large and irregular disparity, which is typical in convergent multiview camera setups. Compared with the existing state-of-the-art fast ME approaches, our proposed DE can obtain a similar coding efficiency while achieving a significant speedup for interviewpoint prediction and coding. Moreover, a robustness study shows that the proposed DE algorithm is insensitive to the epipolar geometry estimation noise. Hence, its wide application for multiview image and video coding is promising. [ABSTRACT FROM AUTHOR]

In this paper, we address the key problem in real-time video coding, the rate-distortion (R-D) tradeoff. As most video coding applications employ color images, we analyze the R-D modeling problem of the color image sequence. We investigate that the R-D characteristics of color video signal in traditional transform-based video coding systems should be modeled for the luminance and chrominance components separately. So we propose separable R-D models for color video coding. The feedback from the encoder buffer is analyzed by a control-theoretic adaptation approach to avoid buffer overflow and underflow. To achieve smooth video quality and satisfy the delay constraints in real-time applications, a novel R-D tradeoff controller is designed. In the proposed R-D tradeoff framework, both the quality variation and buffer safety are considered. Extensive simulation results demonstrate that the proposed approach can achieve smooth video quality without sacrificing overall quality while efficiently utilize the bandwidth without buffer overflow or underflow. [ABSTRACT FROM AUTHOR]

H.264/AVC encoder employs a complex mode-decision technique based on rate-distortion optimization. It calculates rate-distortion cost (RDcost) for all possible modes to choose the best one having the minimum RDcost. This paper presents a frame-layer rate control for H.264/AVC that computes the Lagrange multiplier (λM0DE) for mode decision by using a quantization parameter (QP) which may be different from that used for encoding. At the same time, we also compare actual bits produced by previous macroblocks (MBs) with the total bits allocated to these MBs to further modify λMODE. The objective of these measures aims to produce bits as close to the frame target bits for rate control as pos- sible. This is very important in the case of low-bit-rate tight buffer applications. In order to obtain an accurate QP for a frame, we employ a complexity-based bit-allocation scheme and a QP adjust- ment method. Simulation results comparing with the 11.264 Joint Video Team (JVT) rate control method show that the H.264 en- coder, using the proposed algorithm, achieves a visual quality im- provement of about 0.56 dB, performs better for buffer overflow and underfiow, and achieves a smaller PSNR deviation. [ABSTRACT FROM AUTHOR]

In this paper, a novel architecture for two-dimensional (2-D) inverse discrete cosine transform (IDCT) is implemented using 90-nm CMOS technology. By exploiting the sparseness property of a 2-D discrete cosine transform (DCT) coefficient matrix and the even and odd symmetry properties of the basis vectors of the one-dimensional (1-D) DCT, the proposed architecture reduces computational complexity and increases a throughput rate effectively. First, we derive a recursion equation from the definition of the 2-D IDCT algorithm and use it to design an efficient 2-D IDCT architecture. The proposed architecture consisting of processing elements is suitable for very-large-scale-integration implementation due to its highly regular and scalable structure for 2-D N x N IDCT computations. Based on the derived recursion equation, we show how data flow for the outer products scaled by only nonzero 2-D DCT coefficients performs 2-D IDCT naturally with low complexities of the controller and the interconnection. The proposed architecture based on the recursion equation provides optimum balance in both hardware complexity and throughput rate when compared with other 2-D IDCT architectures. [ABSTRACT FROM AUTHOR]