基于随机森林分类的HEVC帧内CU快速划分算法

针对HEVC帧内编码中递归式四叉树编码单元（Coding Unit,CU）划分引起的高计算复杂度问题,提出了基于随机森林分类（Random Forest Classifier,RFC）的CU快速划分算法。该算法包括模型离线训练和CU快速编码算法两部分。在模型离线训练中,将CU最佳划分结果（+1,－1）作为分类标签,将当前CU的对比度、逆差矩和熵信息作为特征属性,训练RFC模型。在编码时,提取当前CU的特征属性值,利用训练好的RFC模型快速预测当前CU的划分结果。实验结果表明,该算法与HEVC的标准算法相比,在保证编码质量的前提下,平均可以节约45.18%的编码时间。     

基于零块分析的高效视频编码通信

为了实现高清、超高清视频实时编码通信传输, 针对高效视频编码(HEVC)帧间编码计算复杂度过高的问题,根据图像的文理复杂度和 编码单元的零块统计特征,提出一种新的HEVC快速帧间模式判决算法。根据Merge模式下 整单元一分为四的4个子编码单元纹 理相似度确定是否提前终止编码单元(CU)划分,同时利用帧间2N×2N预测模式下零系数与非零系数分布的区域统计特征,选择符合零块分 布特征的最佳预测单元(PU)模式。实验结果表明,在低延迟B(LDB,low-delay B)和随机访 问(RA,random access)配置条件下,提出的算法在保持编码 性能基本不变的情况下,HEVC帧间预测编码时间分别平均减少了60.2%与59.4%。     

基于决策树的HEVC SCC帧内编码快速算法

为减少HEVC屏幕内容编码的编码时间,提高编码 效率,本文提出了一种基于决策树的HEVC屏幕内容帧内编码快速 CU划分和简单PU模式选择的算法。对视频序列特性分析,提取有效的特征值,生成决策树模 型。使用方差、梯度信息熵和 像素种类数用于生成CU划分决策树,使用平均非零梯度、像素信息熵等用于生成PU模式分类 决策树。在一定深度的决策 树模型中,通过对相应深度的CU的特征值的计算快速决策当前CU的划分与PU模式的类型。这 种利用决策树做判决的算法 通过减少CU深度和PU的模式遍历而降低编码复杂度,达到快速帧内编码的效果。实验结果表 明,与HEVC屏幕内容的标 准算法相比,该算法在峰值信噪比(PSNR)平均下降0. 05 dB和码率 平均增加1.15%的情况下,能平均减少30.81% 的编码时间。     

基于纹理四叉树的快速HEVC帧内编码算法

针对高效视频编码(HEVC)中编码单元(CU)进行四叉树递归遍历时间较长的问题,提出一种基于纹理四叉树的快速HEVC帧内编码算法。采用Sobel算子对当前视频图像提取边缘,利用最大类间方差法剔除弱边缘并保留强边缘。通过递归方式对边缘图中的每个64×64单元建立纹理四叉树,使用视频图像的纹理四叉树结构对CU最优分割组合进行预测。对于不同大小的分割单元,无需完全递归遍历所有的CU深度,从而缩小CU搜索范围,节省编码时间。实验结果表明,与HEVC标准算法相比,该算法亮度分量的码率平均增加了0.50%,信噪比和编码时间分别减少了0.03d B和28.70%。     

An Effective CU Depth Decision Method for HEVC Using Machine Learning

This paper presents an effective machine learning-based depth selection algorithm for CTU (Coding Tree Unit) in HEVC (High Efficiency Video Coding). Existing machine learning methods are limited in their ability in handling the initial depth decision of CU (Coding Unit) and selecting the proper set of input features for the depth selection model. In this paper, we first propose a new classification approach for the initial division depth prediction. In particular, we study the correlation of the texture complexity, QPs (quantization parameters) and the depth decision of the CUs to forecast the original partition depth of the current CUs. Secondly, we further aim to determine the input features of the classifier by analysing the correlation between depth decision of the CUs, picture distortion and the bit-rate. Using the found relationships, we also study a decision method for the end partition depth of the current CUs using bit-rate and picture distortion as input. Finally, we formulate the depth division of the CUs as a binary classification problem and use the nearest neighbor classifier to conduct classification. Our proposed method can significantly improve the efficiency of inter-frame coding by circumventing the traversing cost of the division depth. It shows that the mentioned method can reduce the time spent by 34.56% compared to HM-16.9 while keeping the partition depth of the CUs correct.     

电力线载波技术重大突破--数字配电线载波技术及其应用

介绍了在电力线载波领域取得的最大突破－－数字配电线载波技术（ＤＰＬ）。该技术可以有效地保护配电线上传输的信号不受干扰,因而使得电力公司可以通过现成的配电线路为用户提供高速、可靠而费用低廉的因特网、多媒体以及其他信息服务。该项技术引起了世界范围的电力界和商业界的广泛关注。目前已有１５０多家电力公司对此进行了业务咨询,其中包括大钦数世界电力公司。     

Experiments on the aging of Sn–Ag–Cu solder alloys

Abstract

The microstructural stability of the Sn–3·8%Ag–0·7%Cu solder alloy was investigated by studying microstructural changes caused by heating small samples for various times, up to 1000 h, at 150°C. The first change, evident at high magnification after heating for 1 h, occurred from the as cast lamellar plus fibrous form of the Ag₃Sn and Cu₆Sn₅ interdendritic eutectic phases to a particulate form. With further heating, coarsening of the two compound phases occurred, gradually rendering the Sn dendrite pattern less distinct. Due to the very rapid diffusion of Cu in solid Sn, the Cu₆Sn₅ phase coarsened most rapidly, growing from its originally finely divided (200 nm) size in the ternary eutectic to form many particles up to 3 m m or more in size in a time of 100 h. At that time, nearly 50% of the total Cu was contained in these particles. The Ag₃Sn phase coarsened more slowly. Approximate measurements of average particle size as a function of time suggested that coarsening occurs by Ostwald ripening, controlled by diffusion in the Sn phase.     

面向5G的C-RAN技术与C-RAN规划案例分析

【】为更好的做好现阶段的4G C-RAN规划和分阶段实施工作,本文试图分析未来5G技术对网络架构产生的影响,为现阶段C-RAN工作提供经验分享和案例参考。重点分析了未来5G无线网设备形态、基于NGFI+C/U分离的的RAN架构,并以某地区C-RAN区域划分、机房规划为实际案例,介绍了其向5G网络架构演进的预判和思考。     

Efficient prediction of CU depth and PU mode for fast HEVC encoding using statistical analysis

High Efficiency Video Coding (HEVC) adopts complex quadtree-structured CU (coding unit) and PU (prediction unit) modes. Thus, the search process for optimal modes causes high computational complexity in HEVC. To solve this problem, a fast coding algorithm is proposed. Thirteen neighboring CTUs (Coding Tree Unit) are divided into three classes with the k-means method, and are selectively used as the reference CTUs to calculate the predicted CU depth levels for the current CTU. Additionally, for every CU depth, we skip some rarely used PU modes to reduce the complexity of the PU selection algorithm. Experimental results show that compared with the HEVC reference software, our algorithm can achieve 56.71% time saving with Low Delay Configuration profile and 59.76% with Random Access Configuration profile, whereas values of BDBR (Bjontegaard Delta Bit Rate) are only 1.0517% and 0.9918%, respectively. Compared with five state-of-the-art algorithms, the proposed algorithm has significant encoding time reduction with good bitrate performances.