视频通信中基于场景切换检测的H．264帧层码率控散

H．264采用的码率控制算法JVT-G012在信道带宽和压缩后图像质量之间取得了不错的平衡。然而,由于没有考虑到场景切换,在JVT-G012控制下包含场景切换的视频序列压缩后的视频质量往往有较大波动。为应对视频通信中可能出现的场景切换,提出了一种新颖的基于场景切换检测的H．264帧层码率控制算法。首先,提出了一种基于宏块级亮度直方图差异的场景切换检测方法。然后,使用结合跳帧控制的可变长GOP处理检测到的场景切换。仿真结果显示,和JVT-G012相比,所提码率控制算法能够有效应对视频序列中可能出现的场景切换,在同等码率下显著提高整个序列的平均PSNR,并且保持了较低的编码器缓冲区占用度。     

视频通信中基于场景切换检测的H.264帧层码率控制

H.264采用的码率控制算法JVT-G012在信道带宽和压缩后图像质量之间取得了不错的平衡.然而,由于没有考虑到场景切换,在JVT-G012控制下包含场景切换的视频序列压缩后的视频质量往往有较大波动.为应对视频通信中可能出现的场景切换,提出了一种新颖的基于场景切换检测的H.264帧层码率控制算法.首先,提出了一种基于宏块级亮度直方图差异的场景切换检测方法.然后,使用结合跳帧控制的可变长GOP处理检测到的场景切换.仿真结果显示,和JVT-G012相比,所提码率控制算法能够有效应对视频序列中可能出现的场景切换,在同等码率下显著提高整个序列的平均PSNR,并且保持了较低的编码器缓冲区占用度.     

基于场景切换的H.264码率控制技术

在H.264/AVC编码器中,由于采用了固定长度的图像组(GOP)结构,不能有效地处理视频序列中的场景切换,导致场景切换帧后续各帧编码质量严重下降。为了有效解决该问题,提出一种自适应的码率控制算法,通过场景切换的快速检测方法检测视频序列中的场景切换,在场景切换帧处终止当前GOP并对GOP层的码率分配算法做出修正。仿真结果表明:采用该算法可以有效地降低场景切换对后续帧编码质量的影响,而且合理地分配码率资源,提高了整个视频序列的编码质量。在相同码率条件下,整体编码质量可以提高0.3~0.5 dB。     

基于场景切换的H.264码率控制技术

在H.264/AVC编码器中,由于采用了固定长度的图像组(GOP)结构,不能有效地处理视频序列中的场景切换,导致场景切换帧后续各帧编码质量严重下降。为了有效解决该问题,提出了一种自适应的码率控制算法,通过场景切换的快速检测方法检测视频序列中的场景切换,在场景切换帧处终止当前GOP并对GOP层的码率分配算法做出修正。仿真结果表明:采用该算法可以有效地降低场景切换对后续帧编码质量的影响,而且合理地分配码率资源,提高了整个视频序列的编码质量。在相同码率条件下,整体编码质量可以提高0.3-0.5dB。     

基于场景切换的B帧量化参数分配方法

H.264/SVC实现了对基本层码率控制,但对于视频序列中场景切换并没有有效的检测,也没有考虑到场景切换对视频编码质量的影响.本文结合H.264/SVC特有的分层B帧预测金子塔编码结构,首先提出一种改进的基于图像复杂度的实时场景切换检测算法,结合场景切换的类型,再对存在场景切换的GOP编码单元中时间分级的高层B帧量化参数进行修改.实验结果表明在不产生信道码率突变的前提下,明显改善了场景切换处的视频质量.     

基于场景切换的码率控制方法

基于对H.264码率控制算法的研究,考虑到图像中编码帧的复杂度和场景切换,提出了场景切换检测方法和相应的码率控制算法,实验结果表明,与以前的算法相比,论文提出的方法在准确控制码率的同时,图像的视觉质量也得到了提高。     

基于场景检测的错误隐藏技术

提出了可以用于H.264/AVC解码器的基于场景变换检测的错误隐藏机制,首先利用H.264/AVC的快速准确的检测是否发生场景切换,根据场景切换检测结果对预测帧和I帧分别提出相应的时间空间自适应的错误隐藏方法. 实验结果表明,所提方法在错误隐藏的重构图像质量在主观感觉和客观PSNR定量上,都比通常的方法有明显的提高;与传统错误隐藏方法相比,本文的基于场景切换检测的错误隐藏机制鲁棒性高,更能适应的H.264/AVC更为复杂的多种应用场合.     

一种新的H.264自适应帧层码率控制算法

本文提出了一种基于宏块亮度直方图差异(BH, Block Histogram difference)和带宽充裕度估计的H.264帧层码率控制算法。该算法使用基于BH的相对复杂度检测场景切换,并在各场景的开始阶段对当前信道带宽充裕度做出判断。之后在帧层码率控制中,根据基于BH的相对复杂度对各帧的目标比特进行加权调整。最后根据信道带宽充裕度的判断结果做进一步调整。仿真结果表明所提算法能够适应信道带宽和视频序列编码复杂度之间的不同关系,并在视频序列使用的信道带宽和压缩后的图像质量之间取得了比JVT-G012更好的平衡。     

基于场景切换检测的码率控制策略

分析了场景切换下ＴＭ５率控制算法失效的原因,指出Ｐ,Ｂ帧预测效果下降到Ｉ、Ｐ帧目标比特数计算误差加大是导致图像编码质量下降的主要因素,提出了基于场景切换检测和视觉时域掩盖效应的码率控制策略,并在场景切换时对ＴＭ５算法得到的目标比特数进行了修正。实验表明,该方法可以在保证编码缓冲区不发生上溢的前提下改善切换点及后续帧的图像编码质量。     

CSN切换移动检测与数据完整性的研究

移动检测是支持移动终端进行切换的先决条件,数据完整性是移动终端在切换过程中不丢失分组的重要指标.针对WiMAX网络技术规范中基于IPv6的CSN锚点移动性管理场景的移动检测方案与IETF的移动检测方案不一致和切换过程中不能保证数据完整性的问题,提出了改进的增强型CSN锚点移动性管理方案.该方案没有增加新的网络实体和信令消息,解决了WiMAX规范和IETF规范在移动检测方面的兼容性,保证了CSN锚点移动性管理过程中的数据完整性,完善了CSN锚点移动性管理机制,提高了CSN锚点移动性管理性能.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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