共查询到20条相似文献，搜索用时 46 毫秒
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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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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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结合空时OFDM和转换编码技术,提出了一种无线衰落信道下具有可分级转码能力的鲁棒视频传输方法.采用可分级转码器将高质量的MPEG-2压缩视频转换为低码率、低分辨率MPEG-4可分级码流来满足网络带宽和终端设备显示的要求.在接收端采用一种层干扰抑制算法,使得分层空时OFDM系统不同层的传输性能存在差异,从而使系统具有不对等保护能力.根据分级码流的重要程度不同,将转码输出的可分级码流分别由分层空时编码OFDM系统的不同层来实现视频的鲁棒传输.实验结果表明:在典型的随机突发错误的无线环境下,提出的具有可分级转码能力的系统的视频传输性能优于传统的非分级转码的视频传输系统. 相似文献
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Current multi-view video coding （MVC） reference model in joint video team （JVT） does not provide efficient rate control schemes. This paper presents a rate control algorithm for MVC by improving the quadratic rate-distortion （R-D） model. We reasonably allocate bit-rate among views based on the correlation analysisl The proposed algorithm consists of three levels to control the rate bits more accurately, of which the frame layer allocates bits according to the frame complexity and the temporal activity. Extensive experiments show that the proposed algorithm can control the bit rate efficiently. 相似文献
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LI Mao-quan XU Zheng-quan 《浙江大学学报(A卷英文版)》2006,7(12):2057-2062
INTRODUCTION Currently, main video coding algorithms, such as H.26x and MPEG families are all based on block discrete cosine transform (BDCT). At low bit rate, all these BDCT-based algorithms suffer from visible blocking artifacts, which are easily noticeable as the discontinuities between neighboring blocks, particu- larly in flat and low activity homogeneous areas of the image because high frequency DCT coefficients are inclined to be quantizd to zeros due to the high quan- tizatio… 相似文献
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Concerning inter4v mode employed widely in MPEG-4 video, a new temporal error concealment scheme for MPEG-4 video sequences is proposed, which can selectively interpolate one or four motion vectors (MVs) for the missing macroblock (MB) according to the estimated MB coding mode. Performance of the proposed scheme is compared with the existing schemes with multiple testing sequences at different bit error rates. Experimental results show that the proposed algorithm can mask the impairments caused by transmission errors more efficiently than 0 MV and average MV methods by consuming more time for different bit error rates. It has an acceptable image quality close to that obtained by the selective motion vector matching (SMVM) algorithm, while taking less than half of cycles of operations. The proposed concealment scheme is suitable for low complexity video real-time implementations. 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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针对MPEG-2标准,提出一种新的盲水印算法,首先使用领域平均的方法,计算载体视频两条I帧DCT变换低频系数均线的交叉点作为嵌入位置,然后利用奇偶量化的方法实现水印信息与同步码的嵌入。实验表明,算法具有较好的不可见性,且针对常规攻击具有较强的鲁棒性。 相似文献
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WU Jing YE Xiu-qing GU Wei-kang 《浙江大学学报(A卷英文版)》2007,8(6):841-848
This paper proposes a new adaptive post-filtering algorithm to remove coding artifacts in block-based video coder. The proposed method concentrates on blocking and ringing artifacts removal. For de-blocking, the blocking strength is identified to determine the filtering range, and the maximum quantization parameter of the image is used to adapt the 1D fuzzy filter. For de-ringing, besides the edge detection, a complementary ringing detection method is proposed to locate the neglected ringing blocks, and the gradient threshold is adopted to adjust the parameter of 2D fuzzy filter. Experiments are performed on the MPEG-4 sequences. Compared with other methods, the proposed one achieves better detail preservation and artifacts removal performance with lower computational cost. 相似文献
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In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS) stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution. 相似文献
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In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS) stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution. 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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新一代的音视频压缩标准MPEG-4不断走向成熟,成为视频应用的不可或缺的一个基础标准,具有的高压缩率、强交互能力和灵活分级能力,使之在网络媒体特别是视频点播中拥有广阔的应用前景。本文针对视频点播系统的应用,提出了MPEG-4视频点播系统的结构,实现了MPEG-4视频点播服务器的构建。 相似文献
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实时背景更新是数字视频监控中进行运动目标检测的关键技术,与基于PC的监控系统不同,嵌入式系统资源有限,难以执行复杂算法。为此提出一种帧间差分和背景减除法相结合的新方法,通过引入备份帧,有效实现了监控系统的自适应背景更新,并在嵌入式处理器DM6437上实现。实验结果表明该方法可以自动检测物体进出所引起的背景变化并进行背景更新,更新速度快,能够满足实时监控系统目标检测的需要。 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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YIN Ming WANG Hong-yuan 《浙江大学学报(A卷英文版)》2006,7(6):990-995
INTRODUCTION Rate control has been playing an increasing important role in real-time video communication. An encoder employs rate control to regulate output bit- streaming to meet certain channel bandwidth and buffer constraints while pursing high video quality. One fundamental problem in the encoder design is the selection of quantization parameter (QP) to maximize visual quality under constraints imposed by the computational complexity, delay, bandwidth and/or loss factors. At present… 相似文献
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LIU Yun-qiang YU Song-yu WANG Xiang-wen ZHOU Jun 《浙江大学学报(A卷英文版)》2006,7(4):543-548
INTRODUCTION Many emerging video applications, such as video-on-demand (VOD) and distance learning, rely on the efficient transfer of compressed video. For the same average bandwidth, variable bit rate (VBR) encoded video streams have higher perceivable qual- ity and greater opportunity for statistical multiplexing gains compared to constant bit rate (CBR) video streams (McManus and Ross, 1996). However, VBR video typically shows significant burstiness on mul- tiple time scales, due … 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