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Optimal bit allocation and efficient rate control for H.264/AVC based on general rate-distortion model and enhanced coding complexity measure

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IET IMAGE PROCESSING 2010年第3期4卷 172-183页

作者： Xie, Z. Bao, Z. Xu, C. Zhang, G. Nantong Univ Sch Elect & Informat Nantong 226007 Peoples R China

A general rate-distortion (RD) model for block-based video coding is proposed in this study. Based on this model, an innovative coding characteristic called texture-complexity (TC), which is defined as a function of discrete cosine transform (DCT) coefficient distribution and distortion-quantisation (DQ) relationship as well as variance of residual block, is presented for rate control. Moreover, an adaptive linear TC forward-prediction model is established to estimate the characteristic of incoming image block, and a head bits prediction model as well as an optimal bits allocation method are also proposed to best allocate available bits. Experimental results show that the H. 264 encoder (JM15.1), using the proposed rate control algorithm, achieves an objective quality improvement up to 0.434 dB, produces flatter bit-rate/PSNR curve and meets closer target bits budget than outcomes of JM15.1 rate control method (JVT-W042).

关键词： Rate distortion Video coding image patch Postoperative Residual Curarization discrete cosine transforms rate control Prediction models Quality Improvement Budgets encoding complexity

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Rate-distortion optimised quantisation for direct current coefficients of Wyner-Ziv frame in unidirectional distributed video coding

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IET IMAGE PROCESSING 2012年第8期6卷 1064-1074页

作者： Liu, H. Song, B. Liu, J. Qin, H. Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Peoples R China

This study presents a rate-distortion (RD) optimised quantisation algorithm for direct current (DC) coefficients of the Wyner-Ziv (WZ) frames in unidirectional distributed video coding. As the side information (SI) could be viewed as a 'corrupted' version of the original WZ frame, the correlation noise (WZ-SI) can be interpreted as a virtual channel with an error pattern. In this study, the distortion caused by virtual channel errors, besides quantisation errors, is analysed emphatically for unidirectional WZ video coding. In their presented quantisation algorithm, a novel RD model is developed to find out the optimal quantisation step size, in which the quantisation distortion and virtual channel error distortion together with the encoding rate are formulated using the quantisation step size without feedback channels. Then the RD optimal step size for DC coefficients can be solved through minimising the RD cost. In simulations, the comparison of RD performance between their proposed algorithm and the quantisation method used in distributed coding for video services (DISCOVER) is presented. Experimental results show that the proposed RD optimised quantisation for DC coefficients can improve the average peak signal-to-noise ratio of WZ frames by 0.4-1.2 dB for quarter common intermediate format (QCIF) sequences and 0.2-0.4 dB for common intermediate format (CIF), at the expense of increasing the encoding complexity slightly.

关键词： rate-distortion optimised quantisation algorithm quantisation distortion QCIF unidirectional distributed video coding direct current coefficients encoding complexity DISCOVER encoding rate rate-distortion optimised quantisation Image and video coding Wyner-Ziv frame DC coefficients distributed coding for video services quantisation (signal) video coding virtual channel distortion side information Video signal processing quarter common intermediate format optimal quantisation step size virtual channel error distortion

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AN OPTIMAL-DESIGN PROCEDURE FOR INTRABAND VECTOR QUANTIZED SUBBAND CODING

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IEEE TRANSACTIONS ON COMMUNICATIONS 1995年第2-4期43卷 523-533页

作者： BRADLEY, JN STOCKHAM, TG MATHEWS, VJ UNIV UTAH DEPT ELECT ENGN SALT LAKE CITY UT 84112 USA

Subband coding with vector quantization is addressed in this paper. Forming the data vectors from both between and within the subbands is considered. The former of these two schemes is referred to as interband coding and the latter as intraband coding. Interband coder design is relatively straightforward since the design of the single codebook involved follows readily from a representative set of interband data vectors. Intraband coder design is more complicated since it entails the selection of a vector dimension and a bit-rate for each subband. The main contribution of this work is an optimal methodology for intraband subband vector quantizer design. The problem formulation includes constraints on the bit-rate and the encoding complexity and is solved with nonlinear programming methods. Subband vector quantization image coding in conjunction with a human visual system model is thoroughly investigated. Results of a large number of experiments indicate that the optimal intraband coder yields superior results from quantitative as well as' subjective points of view than the interband coder for comparable bit-rates. This improvement becomes more pronounced as the computational complexity of the intraband encoder is allowed to increase.

关键词： intermediate zone encoding complexity ENCODER subband coding Vector quantization subband Problem Formulation

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Fast mode decision method based on edge feature for HEVC inter-prediction

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IET IMAGE PROCESSING 2018年第5期12卷 644-651页

作者： Tsai, Tsung-Han Su, Sheng-Shuan Lee, Ting-Yu Natl Cent Univ Dept Elect Engn Taoyuan Taiwan

High-efficiency video coding (HEVC) is an international video coding standard. It can reduce bit rate by almost 50% when preceding state-of-the-art standard H.264/advanced video coding (AVC) with the same objective quality but increase about 40% encoding complexity. The computation complexity of HEVC largely relies on the inter-prediction, which consumes about 60-70% of the total encoding time. This study proposes a fast mode decision method for HEVC inter-prediction. Since current coding unit (CU) is the basic coding zone for HEVC encoding process, the authors apply the edge detection method with Sobel operator to extract the edge information inside CU. It is based on the threshold-oriented means to compare those edge values and then predict the best partition mode for this CU. Furthermore, they define a weighting factor to adopt various resolutions of test sequence from wide quarter video graphics array (WQVGA) to 1600p. The experimental results show that the proposed algorithm can reduce computational complexity by 50% on average compared with HEVC reference software, and appear to have almost the same coding performance.

关键词： video coding feature extraction edge detection computational complexity fast mode decision method edge feature HEVC interprediction high-efficiency video coding interprediction international video coding standard H 264 encoding complexity computation complexity reduction total encoding time HEVC encoding process coding unit coding zone edge detection method Sobel operator edge information extraction threshold-oriented means weighting factor test sequence

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Fast Multi-Type Tree Partitioning for Versatile Video Coding Using a Lightweight Neural Network

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IEEE TRANSACTIONS ON MULTIMEDIA 2021年 23卷 4388-4399页

作者： Park, Sang-hyo Kang, Je-Won Kyungpook Natl Univ Sch Comp Sci & Engn Daegu 41566 South Korea Ewha Womans Univ Dept Elect & Elect Engn Seoul South Korea Ewha Womans Univ Smart Factory Multidisciplinary Program Seoul South Korea

In this paper, we propose a fast decision scheme using a lightweight neural network (LNN) to avoid redundant block partitioning in versatile video coding (VVC). A more versatile block structure, named the multi-type tree (MTT) structure, which includes binary trees (BTs) and ternary trees (TTs), is adopted by VCC, in addition to the traditional quadtree structure. The MTT improved the coding efficiency compared with previous video coding standards. However, the new tree structures, mainly TT, significantly increased the complexity of the VVC encoder. Although widespread application of VVC has been inhibited, this problem has not yet been investigated thoroughly in the literature. In this study, we first determine the statistical characteristics of coded parameters that exhibit correlation with the TT and develop two useful types of features-explicit VVC features (EVFs) and derived VVC features (DVFs)-to facilitate the intra coding of VVC. These features can be obtained efficiently during the intra prediction before the determination of the best block partitioning during rate-distortion optimization in VVC encoding. Our LNN model decides whether to terminate the nested TT block structures subsequent to a quadtree based on the features. The experimental results confirm that the proposed method substantially decreases the encoding complexity of VVC with a slight coding loss under the All Intra configuration. Our code, models, and dataset are available at https://***/foriamweak/MTTPartitioning_LNN.

关键词： encoding complexity theory Image coding Transforms Tools Standards Quantization (signal) Block partitioning Deep learning encoding complexity Image compression Intra prediction Multi-type tree Neural network Video compression VVC

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Two New Classes of Two-Parity MDS Array Codes With Optimal Repair

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IEEE COMMUNICATIONS LETTERS 2016年第7期20卷 1293-1296页

作者： Wang, Yan Yin, Xunrui Wang, Xin East China Jiao Tong Univ Sch Software Nanchang 330013 Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian 710126 Peoples R China Univ Calgary Dept Comp Sci Calgary AB T2N 1N4 Canada Fudan Univ Sch Comp Sci Shanghai 201203 Peoples R China

Two-parity maximum distance separable (MDS) array codes achieve the lowest storage overhead for tolerating two erasures. In this letter, we propose two new classes of two-parity MDS array codes over finite field F-2, with which each single node failure can be recovered by reading the minimum amount of data from each surviving node.

关键词： Distributed storage systems erasure codes RAID-6 codes disk I/O encoding complexity

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MDR Codes: A New Class of RAID-6 Codes with Optimal Rebuilding and encoding

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2014年第5期32卷 1008-1018页

作者： Wang, Yan Yin, Xunrui Wang, Xin Fudan Univ Sch Comp Sci Shanghai Peoples R China Univ Calgary Dept Comp Sci Calgary AB T2N 1N4 Canada East China Jiaotong Univ Sch Software Nanchang Peoples R China

As storage systems grow in size, device failures happen more frequently than ever before. Given the commodity nature of hard drives employed, a storage system needs to tolerate a certain number of disk failures while maintaining data integrity, and to recover lost data with minimal interference to normal disk I/O operations. RAID-6, which can tolerate up to two disk failures with the minimum redundancy, is becoming widespread. However, traditional RAID-6 codes suffer from high disk I/O overhead during recovery. In this paper, we propose a new family of RAID-6 codes, the Minimum Disk I/O Repairable (MDR) codes, which achieve the optimal disk I/O overhead for single failure recoveries. Moreover, we show that MDR codes can be encoded with the minimum number of bit-wise XOR operations. Simulation results show that MDR codes help to save about half of disk read operations than traditional RAID-6 codes, and thus can reduce the recovery time by up to 40%.

关键词： RAID-6 codes disk I/O encoding complexity distributed storage systems erasure codes

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Low-Density Codes Based on Chaotic Systems for Simple encoding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2009年第2期56卷 405-415页

作者： Kozic, Slobodan Hasler, Martin Swiss Fed Inst Technol CH-1015 Lausanne Switzerland

This paper proposes a new class of low-density generator-matrix codes (LDGM) based on chaotic dynamical systems. The codes are designed by controlling symbolic dynamics and using linear convolutional codes. Analyzing the complex structure of chaotic systems, iterative decoding is developed. The communication performance is studied, and convergence analysis of the iterative-decoding system is presented. Finally, comparison and advantages over LDGM linear block codes in terms of encoding complexity and bit-error-rate performance are described, and possible applications of our codes are discussed.

关键词： Chaos encoding complexity factor graphs iterative-decoding analysis low-density codes

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A Multirate Fully Parallel LDPC Encoder for the IEEE 802.11n/ac/ax QC-LDPC Codes Based on Reduced complexity XOR Trees

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IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS 2021年第1期29卷 51-64页

作者： Mahdi, Ahmed Kanistras, Nikos Paliouras, Vassilis Univ Thessaly Elect & Comp Engn Dept Volos 38221 Greece Univ Patras Elect & Comp Engn Dept VLSI Design Lab Patras 26500 Greece

This article proposes an encoding method based on a two-step encoding algorithm for the 12 quasi-cyclic (QC)-low-density parity-check (LDPC) (QC-LDPC) codes specified in the IEEE 802.11n/ac/ax standards. The proposed approach jointly considers all codes of the particular set, instead of targeting each code separately. The proposed algorithm performs multiplication by inverse matrices. The complexity of the multiplications is significantly reduced by the introduced encoding method. It allows the implementation of full-parallel architectures that execute the encoding process within a single clock cycle, or more for pipelined implementations, for any of the supported codes. A corresponding VLSI encoding architecture based on XOR-gate trees is also proposed. The proposed solution exploits the structure and features of the involved matrices to extract common subexpressions (CSs) using common sub-expression sharing techniques (CSST). Such expressions result due to common features of the original matrices and the corresponding inverses, identified in this article. Innovative subexpression extraction procedures that target the specific codes as a set are introduced here. Furthermore, illustrative single-clock hardware encoders derived by the proposed technique are integrated into 90- and 45-nm technologies at 1 GHz occupying 125 and 107 KGates, respectively, achieving throughput rates up to 1.62 Tbps.

关键词： encoding Parity check codes Computer architecture Phase change materials Hardware complexity theory Wireless fidelity Common subexpression (CS) complexity reduction encoding complexity low-density parity-check (LDPC) encoding matrix inversion multi-Gbps throughput rate quasi-cyclic (QC) LDPC VLSI architecture

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In place differential file compression

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COMPUTER JOURNAL 2005年第6期48卷 677-691页

作者： Shapira, D Storer, JA Brandeis Univ Dept Comp Sci Waltham MA 02254 USA

We present algorithms for in-place differential file compression, where a target file T of size n is compressed with respect to a source file S of size m using no additional space in addition to the that used to replace S by T;that is, it is possible to encode using m + n + O(1) space and decode using MAX(m,n) + O(1) space (so that when decoding the source file is overwritten by the decompressed target file). From a theoretical point of view, an optimal solution (best possible compression) to this problem is known to be NP-hard, and in previous work we have presented a factor of 4 approximation (not in-place) algorithm based on a sliding window approach. Here we consider practical in-place algorithms based on sliding window compression where our focus is on decoding;that is, although in-place encoding is possible, we will allow O(m + n) space for the encoder so as to improve its speed and present very fast decoding with only MAX(m, n) + O(1) space. Although NP-hardness implies that these algorithms cannot always be optimal, the asymptotic optimality of sliding window methods along with their ability for constant-factor approximation is evidence that they should work well for this problem in practice. We introduce the IPSW algorithm (in-place sliding window) and present experiments that indicate that it compares favorably with traditional practical approaches, even those that do not decode in-place, while at the same time having low encoding complexity and extremely low decoding complexity. IPSW is most effective when S and T are reasonably well aligned (most large common substrings occur in approximately the same order). We also present a preprocessing step for string alignment that can be employed when the encoder determines significant gains will be achieved.

关键词： Sulfur Nondeterministic polynomial-time hard DECODING sliding windows window method encoding complexity algorithms ENCODER

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