一种低照度视频序列增强算法

为了提高低照度视频的视觉效果,提出一种基于对数图像处理（LIP）的增强算法和改进的双向均衡算法相结合的方法,并运用帧间互相关信息,在保证视觉效果的前提下,减少了处理的帧数,提高了处理的速度。实验结果表明,该方法简单、实用,能够得到较理想的效果。     

An efficient parallel algorithm for motion estimation in very low bit‐rate video coding systems

Motion estimation is widely used in video coding schemes in order to reduce the inherent temporal redundancy among the frames of a video stream. In particular, low and very low bit rate video coding schemes need sophisticated motion models which usually require a large number of arithmetic operations. In this paper we present a parallel algorithm for the most practical of these models. Specifically we implement the affine motion model on a hypercube‐based multiprocessor. This model covers the most usual kinds of motion and requires only a modest number of arithmetic operations. Also, the hypercube network can efficiently handle the non‐regular data flow resulting from the parallel implementation of this model. In addition, we assume that our multiprocessor is fine grained, in contrast to most programmable architectures used in video coding, where processors usually have large local memory. Apart from its practicality, the constraint of limited local memory makes the algorithm design more challenging and thus more theoretically interesting. Finally, with regard to other proposals in the literature, our scheme is more general: whereas our scheme covers all kinds of motion supported by the affine motion model, the rest of the proposals deal only with a subset of these kinds. Copyright © 2000 John Wiley & Sons, Ltd.     

Asynchronously compensated synchronization algorithm for multiple harmonic oscillators with communication delay

Synchronization problem is investigated for multiple harmonic oscillators with identical communication delay in this paper. We propose a new distributed control algorithm in asynchronously compensated form and a corresponding reduced‐order observer‐based distributed control algorithm. By using frequency‐domain analysis, delay‐dependent and delay‐independent convergence conditions are obtained for our proposed algorithms under leader‐following and leaderless coordination control structures, respectively, and the results can be directly extended to the observer‐based algorithm based on the separation principle. Numerical examples illustrate the validity of the theoretical findings. Copyright © 2016 John Wiley & Sons, Ltd.     

考虑通信延迟的多自治水下航行器协同定位算法

自治水下航行器(AUV)协同定位中通信延迟具有常态性. 面对延迟到达的信息, 传统方法一般会有定位精 度或实时性的损失. 针对通信延迟的不利影响, 本文在建立水声探测和通信时延模型的基础上, 以扩展卡尔曼滤波 (EKF)为算法框架, 提出了信息顺序到达和信息出序到达2种协同定位算法, 并以建构面向信息出序情景的算法为 主要创新工作. 在信息顺序到达算法中, 将延迟信息进行序贯处理以减小定位误差. 在信息出序到达算法中, 以信 息出现一步滞后的延迟为背景, 使用出序信息直接对从AUV最新状态估计进行再更新, 信息无损地实时估计运动 状态. 计算机仿真实验结果表明, 本文算法相比于传统的航位推算、整周期滤波、量测丢弃等方法, 具有更高的估计 精度; 相比于数据缓存滤波、重新滤波等方法, 具有强实时性.     

Blind quality scalable video compression algorithm for low bit-rate coding

Multimedia Tools and Applications - An efficient way of using Embedded Zero-trees of Wavelet (EZW) architecture for video compression, termed as “Two Threshold EZW”, has been introduced...     

Efficient algorithm for very low bit rate embedded image coding

The authors propose an embedded wavelet-based image coding algorithm that exploits both the inter- and intra-subband correlations among the wavelet coefficients. The proposed coding algorithm is based on spatial orientation trees (SOT) in which the basic unit is a block of m times n coefficients in contrast to a single coefficient in the set partitioning in hierarchical trees (SPIHT) algorithm. Each SOT has a root node (a block of m times n coefficients) in the LL-subband with the child and descendent blocks in the high frequency subbands. Thus it fuses the features of both block- and tree-based coding algorithms into a single algorithm. Performance of the proposed method is compared (in terms of rate-distortion performance) with the other state-of-the-art coding algorithms including the JPEG2000 for popular test images. Simulation results show that the proposed algorithm has a better coding efficiency over the other coders at very low bit rates. Also, compared with SPIHT it reduces the elements of the auxiliary lists, thereby reducing the memory requirements. In addition, the encoder of the proposed algorithm is significantly faster than that of the SPIHT, but with a slight increase in its decoder complexity.     

A robust method for estimating synchronization and delay of audio and video for communication services

One of the main contributions to the quality of experience in streaming services or in two-way communication of audio and video applications is synchronization. This has been shown in several studies and experiments but methods to measure synchronization are less frequent, especially for situations without internal access to the application and independent of platform and device. In this paper we present a method for measuring synchronization skewness as well as delay for audio and video. The solution incorporates audio and video reference streams, where audio and video frames are marked with frame numbers which are decoded on the receiver side to enable calculation of synchronization and delay. The method has been verified in a two-way communication application in a transparent network with and without inserting known delays, as well as in a network with 5 and 10 % packet loss levels. The method can be used for both streaming and two-way communication services, both with and without access to the internal structures, and enables measurements of applications running on e.g. smartphones, tablets, and laptops under various conditions.     

低延迟低码率语音编码研究

现有的低延迟语音编码算法（LD-CELP）需要16 kb/s比特率,无疑会妨碍它的应用。提出了一种采用两阶段码书搜索的方法可以在提高低延迟语音编码算法性能的同时降低码率。首先构造了两个子码书：一个后向更新的自适应码书和一个具有代数结构的固定码书;然后设计了两阶段码书搜索方法使滤波后的激励矢量和目标矢量之间的均方误差保持最小。这样就得到了一个在8 kHz采样率下具有2.5 ms延迟的10 kb/s两阶段码书搜索的CELP编码器。用平均分段信噪比（SSNR）和感知语音质量评价（PESQ）测试,本算法具有和16 kb/s的G.728相当的编码质量。     

Encoder-independent decoder-dependent depth-assisted error concealment algorithm for wireless 3D video communication

Three-Dimensional Multi-View Video (3D MVV) contains diverse video streams taken by different cameras around an object. Thence, it is an imperative assignment to fulfill efficient compression to attain future resource bonds whilst preserving a decisive reception MVV quality. The extensive 3D MVV encoding and transmission over mobile or Internet are vulnerable to packet losses on account of the existence of severe channel faults and restricted bandwidth. In this work, we propose a new Encoder-Independent Decoder-Dependent Depth-Assisted Error Concealment (EIDD-DAEC) algorithm. It invests the depth correlations between the temporally, spatially, and inter-view adjoining Macro-Blocks (MBs) to conceal the erroneous streams. At the encoder, the existing inter-view, temporal, and spatial matching are exploited to efficiently compress the 3D MVV streams and to estimate the Disparity Vectors (DVs) and Motion Vectors (MVs). At the decoder, the gathered MVs and DVs from the received coded streams are used to calculate additional depth-assisted MVs and DVs, which are afterwards combined with the collected candidate texture color MVs and DVs groups for concealing the lost MBs of inter- and intra-encoded frames. Finally, the optimum DVs and MVs concealment candidates are selected by the Directional Interpolation Error Concealment Algorithm (DIECA) and Decoder Motion Vector Estimation Algorithm (DMVEA), respectively. Experimental results on several standardized 3D MVV sequences verified the efficacy of the proposed EIDD-DAEC algorithm by achieving ameliorated efficacious objective and subjective results without generating and transporting depth maps at the encoder. The proposed work achieves high 3D MVV quality performance with an improved average Peak Signal-to-Noise Ratio (PSNR) gain by up to 0.95 ~ 2.70 dBs compared to the state-of-the-art error concealment algorithms, which do not employ depth-assisted correlations at different Quantization Parameters (QPs) and Packet Loss Rates (PLRs) of 40%.     

The effect of video feedback delay on frustration and emotion communication accuracy

Previous research has demonstrated that for unacquainted dyads and groups interacting over video, feedback delay can interfere with the impression-formation process and increase cognitive load, in turn leading to incorrect interpersonal judgments. In this study, 35 dyads participated in two 10-min conversation periods over video monitors. In one period there was a 1-s delay in the audio/video signal and in the other there was no delay. In period 1 the presence of feedback delay was associated with decreased frustration and increased ability to accurately judge a partner’s emotions. In period 2, however, feedback delay was associated with increased frustration and had no effect on emotion communication accuracy, which was decreased in both conditions by inaccurate assumed similarity. Results supported and expanded the relation-alignment perspective, which states that individuals will consciously attempt to manage their impressions over technological channels, but that they can also be unconsciously influenced by technological distortion.     

考虑通信时滞的分布式电力经济调度算法设计

本文考虑发电机的输出限制和邻居间交换信息时的通信时滞,提出了一种新的权重平衡图下的分布式经济调度算法,该算法对所有发电成本函数为强凸的发电机组成的电力系统都适用.分析了算法的平衡点与发电机最优输出功率之间的关系,并基于Lyapunov稳定性理论和凸分析理论,采用时滞分割的方法,得到了使得算法收敛的充分条件.然后应用该条件,得到了给定参数下的时滞上界,并且定性分析了参数对系统收敛速度的影响.最后,五机电力系统的仿真结果验证了算法的可行性和优越性.     

基于H.264/AVC低比特率视频流的双水印算法

针对H.264/AVC编码标准的新特性，通过对低比特率视频流I帧DCT域量化编码和P帧运动估计过程的研究，提出了一种可同时进行版权保护和完整性认证的双水印算法。实验表明，该算法在水印嵌入时通过Lagrangian最优编码控制技术，比特流达到了较好的率失真平衡；所嵌入的鲁棒水印对重量化编码、帧编辑等攻击具有抵抗性，所嵌入的脆弱水印对各种普通攻击具有较强的敏感性。该算法提取水印时不需对压缩码流完全解码，并且为盲提取，能够满足实时随机检测的需要。     

无人值守传感器网络的低通信成本存储算法

针对无人值守传感器网络的数据存储问题, 提出了一种低通信成本的分布式数据存储算法。算法采用步数为cn的定向随机游走机制, 将网络中的k个源数据包按照一定的接收概率分散存储到了网络中所有的n个节点, 在每个节点形成了一个存储数据包。实验表明, 基于该算法的存储过程完成之后, 即使有部分传感器节点损坏, sink节点只要随机收集到k+ε（ε≥10）个存储数据包, 就能成功计算出原来的k个源数据包。与具有代表性的基于LT码方法相比, 该算法在节约sink节点访问成本的同时, 也将网络的通信时间复杂度从O(n　ln　n)降到了O(n), 具有良好的应用潜质。     

数据传输延时的ZigBee网络混合路由算法研究与优化

针对当前无线传感器网络中数据传输延时的问题,提出一种改进后的基于线性和非线性路由算法的混合传输ZigBee路由算法。改进后的算法引入了路由表,在改进后的算法中进行节点选择。考虑到数据在节点之间传输的跳数问题,节点传输数据时根据节点的剩余能量和自身的深度选择子路由算法。仿真结果表明,该算法能有效地降低节点之间数据传输的延时,提高通信效率。     

改进的SOFM算法及其在低延迟语音编码中的应用

根据低延迟语音编码算法训练码书的尺寸和码字维数的特点,提出了一种改进的自组织特征映射（SOFM）神经网络的码书设计方法。对输入训练矢量以及连接权矢量进行归一化,为降低计算量和提高码书训练质量,采用快速的网络学习决定获胜的神经元并对网络权值分阶段进行自适应调整,最后应用于低延迟语音编码中。实验表明,与传统LBG算法比较,采用SOFM神经网络训练的码书其合成语音的主、客观质量均有较大提高。     

HAPS通信中的低复杂度OFDMA资源分配策略

针对配置于高空平台(HAPS)的OFDMA系统,研究了在平台功率受限情况下的资源分配问题。采用对偶理论,推导了在连续情况下,最小化发送功率时,OFDMA载波、功率、速率分配的最优解,同时利用统计近似法实现算法的实时配置。仿真结果表明,该算法性能与经典C.Y.Wong算法性能大致相同,而算法复杂度仅为线性复杂度,具有较强的实际应用价值。     

生成匀质块排样方式的递推算法

讨论矩形毛坯有约束二维剪切排样问题:将一张板材剪切成已知尺寸的一组毛坯,使排样方式的价值(板材中所含毛坯的总价值)最大;排样方式中每种毛坯的数量不能超过需求量.采用匀质块排样方式,每刀都从当前板材上切下一根水平或竖直的同质条带,其中仅含相同尺寸的毛坯.采用动态递推算法生成匀质块排样方式,在保证解的质量的前提下,有效地缩短计算时间,达到节约材料的目的.     

Synchronization in a network of identical discrete‐time agents with uniform constant communication delay

This paper studies the synchronization problem for a network of identical discrete‐time agents with unknown uniform constant communication delay. When the agents are non‐introspective, the problem is solvable via a decentralized low‐gain‐based synchronization controller if the delay satisfies the proposed upper bound. When the agents are introspective, the synchronization problem can be solved with arbitrary bounded communication delay. Copyright © 2013 John Wiley & Sons, Ltd.     

Robust video communication for ubiquitous network access

Ubiquitous network access implies that video can be streamed to portable devices whether they are moving outdoors or docked at home. Unfortunately, broadband wireless channels and their wired alternatives present a hostile environment for video communication, which manifests itself in error bursts. This paper presents a robust application layer, channel-coding scheme suitable for data-partitioned, compressed video. Data partitioning prioritizes the more important data within a compressed bitstream. In the scheme, the more important compressed data are protected prior to communication over an access network. In particular, window-growth rateless codes are used. This form of rateless code can be incrementally scaled to reflect the importance of the data being protected. The paper gives details of the scheme for achieving this in the context of an H.264/AVC codec’s picture types and structures. The paper considers how best to apply the scheme to H.264/AVC’s data-partitioning modes in a practical manner. Simulations of error-prone channels show that the proposed unequal protection scheme achieves several dBs of improvement in video quality, when compared with equal protection. The simulations modeled both wireless and wired access networks.