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1.
Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality. 相似文献
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Totransmitthemultimediadataovertheinternet ,pre encodedvideobitstreamsarepreferablebecauseofthelimitofthenetworkbandwidth .Inmostcases ,theencodershouldknowthechannelcharacteristicsinad vanceandencodethemasparameters .Consequently ,theflexibilityisreduced .Theratecontrolisemployedtocontroltheoutputbitrateaccordingtonetworkcondi tions.Forwirelessnetworks ,theirbandwidthsaremuchmorelimitedthanwirenetworks.Soratecontrolbecomesespeciallyimportantfortransmittingmultimediaoverthewirelessdomains[1- … 相似文献
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Variable size motion estimation (ME) and disparity estimation (DE) are employed to select the best coding mode for each macroblock (MB) in the current joint multiview video model (JMVM).This technique achieves the highest possible coding efficiency,but it results in extremely large computation complexity which obstructs the multiview video coding (MVC) from practical application.This paper proposes an adaptive early termination of fast mode decision algorithm for MVC.It makes use of the coding information o... 相似文献
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Asymmetric stereoscopic video coding can take advantage of binocular suppression in human vision by representing one of the two views in lower quality.This paper proposes a bit allocation strategy for asymmetric stereoscopic video coding.In order to improve the accuracy of bit allocation and rate control in the left view,a proportionalintegral-derivative controller is adopted.Meanwhile,to control the quality fluctuation between consecutive frames of the left view,a quality controller is adopted.Besides,a fuzzy controller is proposed to control the variation in quality between the left and right views by comparing the PSNR disparity of two views with a fixed threshold,which is used to quantize the binocular psycho-visual redundancy and adjust the quantization parameter (QP) of the right view correspondingly.The proposed algorithm has been implemented in H.264/AVC video codec,and the experimental results show its effectiveness in rate control while keeping a good quality for the left view,and fewer bits are allocated for the right view so that the overall bit rate is saved by 7.2% at most without the loss of subjective visual quality for stereoscopic video. 相似文献
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本文提出了一种针对监控视频序列的分段算法．即通过计算输入视频帧与可更新背景帧的差异计算帧运动量,来实时更新背景,按当前帧与实时背景帧的差异进行聚类,然后按照每帧图像的类别对该视频序列进行分段,并提供了计算每帧图像时间的算法,从而可以确定各段视频的起止时间,该算法可以为后续的各种视频挖掘算法提供前期的视频数据处理,方便后续的视频数据分析． 相似文献
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由于光照变化、物体遮挡和复杂背景条件等众多因素的影响,目标检测一直是机器视觉领域最具有挑战性的问题。首先对视频目标检测算法中的孪生网络系列算法进行分析比较;然后将孪生网络与深度学习相结合,提出并构建全新的孪生网络跟踪器;最后将视频输入到设计好的孪生网络跟踪器中,通过网络对每一帧图像中物体的类别与位置进行准确地实时框选标注。分别将该算法和当前广泛应用的YOLOv3算法在OTB数据集上进行验证测试。测试数据表明:该算法的视频目标检测成功率和准确率均优于YOLOv3算法。 相似文献
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KATSAGGELOS Aggelos K. 《浙江大学学报(A卷英文版)》2006,7(5):801-810
INTRODUCTION Video streaming is becoming one of the major driving forces of next generation wireless networks. For the currently deployed cellular networks, the practical data rates are not enough to support full rate, high quality video applications. As a result, many research efforts have been devoted to adapting video content to reconcile the conflict between the high demand of video quality and the limited wireless communication resources among users. A large body of literature utiliz… 相似文献
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In this paper, multiresolution critical-point filters （CPFs） are employed to image matching for frame rate up-conversion （FRUC）. By CPF matching, the dense motion field can be obtained for representing object motions accurately. However, the elastic motion model does not hold in the areas of occlusion, thus resulting in blur artifacts in the interpolated frame. To tackle this problem, we propose a new FRUC scheme using an occlusion refined CPF matching interpolation （ORCMI）. In the proposed approach, the occlusion refinement is based on a bidirectional CPF mapping. And the intermediate frames are generated by the bidirectional interpolation for non-occlusion pixels combined with unidirectional projection for the occlusion pixels. Ex- perimental results show that ORCMI improves the visual quality of the interpolated frames, especially at the occlusion regions. Compared to the block matching based FRUC algorithm, ORCM1 can achieve 1-2 dB PSNR gain for standard video sequences. 相似文献
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为实现便捷、可靠的日常婴儿心率实时监测,提出一种基于面部图像的非接触式婴儿心率实时监测方法。首先引入欧拉视频放大技术,对一定时间间隔内视频的每一帧图像进行颜色增强处理,从而改善婴儿面部颜色变化微弱、所含心率信息不明显的问题;然后,通过Adaboost算法从每一视频帧中识别出婴儿面部,并从婴儿面部选取脸颊区域作为敏感区域以提取脉搏波信号,以此为基础提出一种改进的反射光强模型,抑制日间因环境光变化引起的干扰以及运动噪声干扰,提高脉搏波信号信噪比;此外采用摄像头的红外自主光源,通过一种基于相空间重构的单通道独立成分分析法分离夜间脉搏波信号的运动噪声,解决因夜间光照条件差引起的婴儿心率监测困难的问题;最后开发整个系统上位机应用程序,并通过实验验证该方法正确性和有效性。 相似文献
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医院管理信息系统的使用是信息技术和现代管理技术发展的必然结果,系统基于J2EE平台的MVC设计模式,采用Struts框架结构,按照现代化医院管理思想,实现了医院管理信息系统的视图、控制器和模型组件的设计与开发,充分体现了使用MVC模式和框架技术在开发web应用程序中的灵活性。 相似文献
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医院管理信息系统的使用是信息技术和现代管理技术发展的必然结果,系统基于 J2EE 平台的 MVC 设计模式,采用 Struts 框架结构,按照现代化医院管理思想,实现了医院管理信息系统的视图、控制器和模型组件的设计与开发,充分体现了使用 MVC 模式和框架技术在开发 web 应用程序中的灵活性. 相似文献
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The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding (MVC). To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates. 相似文献
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The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding （MVC）. To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates. 相似文献
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关键帧提取技术是基于内容检索和视频分析的基础。关键帧的使用减少了视频索引的数据量,同时也为视频摘要和检索提供了一个组织框架。首先介绍了目前关键帧提取技术,然后提出了一种基于互信息量的关键帧提取方法,该算法以帧间互信息量来衡量两帧图像内容的相似性,可以对具体镜头按其特点自动提取出一个或多个关键帧。实验结果表明这种方法可以较好地概括视频内容。 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｉｎｔｅｒｅｓｔｉｎｖｅｒｙｌｏｗｂｉｔ ｒａｔｅｖｉｄｅｏｃｏｄｉｎｇｈａｓｉｎ ｃｒｅａｓｅｄｃｏｎｓｉｄｅｒａｂｌｙｗｉｔｈｔｈｅｃｒｅａｔｉｏｎｏｆｎｅｗｓｅｒｖｉｃｅｓａｎｄａｐｐｌｉｃａｔｉｏｎｓｒｅｑｕｉｒｉｎｇｔｈｉｓｃｌａｓｓｏｆｂｉｔｒａｔｅｓｉｎｔｈｅｉｒｆｕｎｃｔｉｏｎ .Ｗｉｔｈｔｈｉｓｔｒｅｎｄ ,ｏｂｊｅｃｔ ｏｒｉｅｎｔｅｄｖｉｄｅｏｃｏｄｉｎｇｗａｓｆｉｒｓｔｐｒｏｐｏｓｅｄｂｙＭｕｓｍａｎｎｅｔａｌ.ｉｎ 1989[1 ],ａｎｄｈａｓｂｅｅ… 相似文献
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A novel color compensation method for multi-view video coding （MVC） is proposed, which efficiently exploits the inter-view dependencies between views with the existence of color mismatch caused by the diversity of cameras. A color compensation model is developed in RGB channels and then extended to YCbCr channels for practical use. A modified inter-view reference picture is constructed based on the color compensation model, which is more similar to the coding picture than the original inter-view reference picture. Moreover, the color compensation factors can be derived in both encoder and decoder, therefore no additional data need to be transmitted to the decoder. The experimental results show that the proposed method improves the coding efficiency of M VC and maintains good subjective quality. 相似文献
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移动虚拟校园(MVC)的构思与实践 总被引：6，自引：0，他引：6
移动教育已经成为现代教育技术应用的一个新方向，如何将移动计算技术应用于教育正在成为研究的热点。本首先探讨了移动计算技术的原理和特点，讨论了移动计算技术在校园建设中的作用，提出了移动虚拟校园（MVC）的概念，给出了其基本框架。同时，本还对该构架中的多项关键技术进行了研究并开发了多个实用的系统，并正在北京大学进行试用，目前运行效果良好。实践表明，移动虚拟校园在目前的技术条件下是可行的，并能发挥巨大的效益。 相似文献
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视频编辑主要指对视频进行镜头画面剪切和串编。针对目前非线性视频编辑系统编辑性能依赖专用硬件板卡或者对视频源进行编辑时占用较大的CPU和PF使用率,且保存的文件占用较大空间的缺陷,提出纯软件的虚拟编辑的方法。通过创建一个拉模式的源过滤器获取视频文件数据,利用IAM Timecode Generator接口方法,编辑时为每帧编排序号并将各个将要编辑的视频序列的开始与结束的帧序号记录下来,并保存到数据库中;播放时读出数据库中记录的帧序号,在源视频文件中进行帧定位播放。该方法对于AVI格式视频文件进行虚拟编辑,播放过程中画面过渡自然,效果良好。 相似文献
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教室环境中人群密度高、重叠部分较大的特点会给人数统计工作带来困难。基于深度学习 YOLOv3 目标检测算法对学生目标进行检测,并加入 Deep-Sort 算法为核心实时追踪方法,对 YOLOv3 算法检测到的学生目标进行一段时间的跟踪,从而克服传统视频人数统计方法中忽略视频上下帧关联信息的缺点,并且能更好地解决视频遮挡问题。目标检测方法中的损失函数用 tan 方损失函数代替原有交叉熵损失函数,跟踪算法中的卡尔曼滤波算法采用 Levenberg-Marquardt 对修正后的轨迹预测予以优化。最后,对该方法进行性能评价与对比实验,包括是否加入上下文信息对比以及与 SVM 目标检测算法作对比。实验结果表明,此方法在测试集中,加入上下文信息后准确率达 93.4%,召回率达 81.4%。对比 SVM,该方法在教室视频人数统计中准确率提升2.1%,召回率提升 8.9%。 相似文献