共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
多视点视频编码是当前视频编码领域的研究热点之一。在有限的网络带宽下,合理的码率分配可以提高视频主观视觉质量。本文提出一种基于结构相似度的码率分配方法,首先对视频帧提取基于结构相似度的显著图,然后结合显著图对重要宏块和非重要宏块分配不同的QP值,以达到码率分配的目的。实验结果表明,本文方法在有限的带宽下能有效的提高多视点视频的视觉主观质量。 相似文献
3.
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
4.
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
5.
无线多跳网络信道受到码间干扰容易产生信道分配失衡,为了提高无线多跳网络信道均衡性,提出基于判决反馈均衡的无线多跳网络信道分配优化算法,构建无线多跳网络信道模型,采用判决反馈均衡器进行无线多跳网络信道分配过程中的干扰抑制和多径补偿,根据信道多径扩展覆盖的码元数进行网络信道分配过程中的前馈滤波调制,利用直接序列扩频方法进行无线多跳网络信道的线性均衡配置,采用自适应的梯度学习算法实现信道分配均衡设计,基于判决反馈均衡技术实现无线多跳网络信道分配优化。仿真结果表明,采用该方法进行无线多跳网络信道分配的均衡性较好,抗多径干扰能力较强,提高了无线多跳网络的通信质量,降低了输出误比特率。 相似文献
6.
Hou Weidong Mo Yulong Wei Chunlong 《上海大学学报(英文版)》1998,2(4):270-274
ｖｅｌｅｔ ＴｒａｎｓｆｏｒｍTX１ＩｎｔｒｏｄｕｃｔｉｏｎＶｉｄｅｏｃｏｍｍｕｎｉｃａｔｉｏｎｉｓｂｅｃｏｍｉｎｇｉｎｃｒｅａｓｉｎｇｌｙｉｍ－ｐｏｒｔａｎｔｉｎａｐｐｌｉｃａｔｉｏｎｔｏｓｅｖｅｒａｌａｒｅａｓｓｕｃｈａｓｔｅｌｅ－ｃｏｎｆｅｒｅｎ... 相似文献
7.
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
8.
基于迭代的比特和功率分配机制,提出了一种低复杂度的比特和功率分配算法.与传统的迭代分配算法不同,该算法在每次迭代中只需要比较几个特定的子载波.该方法在保持传统迭代算法性能的前提下极大地减小了迭代分配算法的复杂度.此外,通过选择等功率分配方案作为初始方案加快了算法的收敛速度,进一步降低了算法复杂度.仿真结果表明,提出的改进算法在基本不牺牲系统性能的前提下有效地降低了算法复杂度. 相似文献
9.
ＩｍａｇｅＣｏｄｉｎｇＵｓｉｎｇＷａｖｅｌｅｔＴｒａｎｓｆｏｒｍａｎｄＥｎｔｒｏｐｙＣｏｎｓｔｒａｉｎｅｄＶｅｃｔｏｒＱｕａｎｔｉｚａｔｉｏｎｗｉｔｈＱｕａｄｔｒｅｅＳｔｒｕｃｔｕｒｅＶｅｃｔｏｒｓＧａｏＸｉｑｉ（高西奇）ＨｅＺｈｅｎｙａ（何振亚... 相似文献
10.
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
11.
With advanced prediction modes of intra prediction, intra coding of H.264/AVC offers significant coding gains compared with previous video coding standards. It uses an important tool called Lagrangian rate-distortion optimization (RDO) technique to decide the best coding mode for a block, but the computational burden is extremely high. In this paper, we proposed an improved fast intra prediction algorithm including block type selection and mode decision algorithm based on analysis of edge feature of a block. Our algorithm filters out unlikely block type and candidate modes to reduce the RDO calculations. Experimental results showed that the proposed algorithm can reduce the computation complexity of intra prediction from 52.90% to 56.31%, with 0.04 dB PSNR degradation and 2% increase of bit rate. 相似文献
12.
最新的静止图像压缩编码标准JPEG2000,提供了许多容错工具,这些容错工具的基本思想是＂有错误,但我让它局限在尽量小的范围,并跳过它们＂,在误码率较低的通信信道中,这些容错工具能提供良好的容错性能。然而,在像无线信道这种误码率较高且易丢包的通信信道中,解码器就要跳过相当多的数据,不能得到好的重建图像。本文利用经过小波变换的子带间存在较大的空间相关性,提出了一种相关子带间错误补偿技术。实验结果表明,此技术能很好地提高JPEG2000图像在无线信道传输中的鲁棒性。 相似文献
13.
基于Linux的802.11b无线网络MAC层切换的分析和实现 总被引：1，自引：0，他引：1
切换过程对无线移动网络质量有重大的影响,而现阶段的802.11b/g对切换的支持并不理想.文章从理论上分析了802.11b无线网络MAC层切换原理和过程,根据造成切换延迟和丢包的因素,提出了切换算法的改进策略,并且基于Linux系统和开源代码对该算法完成了软件实现.实验结果表明,改进算法可有效提高无线网络MAC层切换的速度. 相似文献
14.
１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｌｉｍｉｔｅｄｔｒａｎｓｍｉｓｉｏｎｂａｎｄｗｉｄｔｈａｖａｉｌａｂｌｅｏｎｃｕｒｒｅｎｔｃｏｍｍｕｎｉｃａｔｉｏｎｃｈａｎｎｅｌｓｓｕｃｈａｓｐｕｂｌｉｃｓｗｉｔｃｈｅｄｔｅｌｅｐｈｏｎｅｎｅｔｗｏｒｋｓ（ＰＳＴＮ... 相似文献
15.
The existing H.264/AVC rate control schemes rarely include the perceptual considerations. As a result, the improvements in visual quality are hardly comparable to those in peak signal-to-noise ratio （PSNR）. In this paper, we propose a perceptual importance analysis scheme to accurately abstract the spatial and temporal perceptual characteristics of video contents. Then we perform bit allocation at macroblock （MB） level by adopting a perceptual mode decision scheme, which adaptively updates the Lagrangian multiplier for mode decision according to the perceptual importance of each MB. Simulation results show that the proposed scheme can efficiently reduce bit rates without visual quality degradation. 相似文献
16.
HOU Wei dong MO Yu long 《上海大学学报(英文版)》1999,(4)
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｐｕｂｌｉｃｓｗｉｔｃｈｅｄｔｅｌｅｐｈｏｎｅｎｅｔｗｏｒｋ（ＰＳＴＮ）ａｎｄｉｔｓｂｒｏａｄｃｏｖｅｒａｇｅｐｒｏｍｏｔｅｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｖａｒｉｏｕｓｖｉｓｕａｌｃｏｍｍｕｎｉｃａｔｉｏｎｓｓｅｒｖｉｃｅｓｏｖｅｒＰＳＴＮ［１］．ＴｈｅａｌｌｏｗｅｄｂｉｔｒａｔｅｏｖｅｒＰＳＴＮｗｉｔｈｖｏｉｃｅｂａｎｄｍｏｄｅｍｉｓｓｔｉｌｌｌｉｍｉｔｅｄｔｏｌｏｗｅｒｔｈａｎ６４ｋｂｉｔ／ｓ,ｗｈｉｃｈｐｒｅｓｅｎｔｓａｇｒｅａｔｃｈａｌｌｅｎｇｅ… 相似文献
17.
18.
We propose the spectrum allocation and resource scheduling algorithms in cognitive point to multipoint （PMP） networks with rapid changes of spectrum opportunities and present a media access control （MAC） protocol based on these algorithms. The objective of spectrum allocation is to make efficient use of the spectrum while maintaining the transceiver synchronization on frequency and time in the network. The objective of resource scheduling is to guarantee the quality of service （QoS） requirements of different kinds of connections and to minimize the total energy consumption in the network as well. By sensing only a small set of possible channels in each slot based on the state transition probability of each channel, our spectrum allocation algorithm achieves high spectrum efficiency in the network. The resource scheduling problem is divided into three sub problems and we derive optimal solutions to these problems by greedy algorithm and convex optimization. The simulation results show that our algorithm can make efficient use of the spectrum and the network resources at a cost of low computational complexity. 相似文献
19.
Totransmitthemultimediadataovertheinternet ,pre encodedvideobitstreamsarepreferablebecauseofthelimitofthenetworkbandwidth .Inmostcases ,theencodershouldknowthechannelcharacteristicsinad vanceandencodethemasparameters .Consequently ,theflexibilityisreduced .Theratecontrolisemployedtocontroltheoutputbitrateaccordingtonetworkcondi tions.Forwirelessnetworks ,theirbandwidthsaremuchmorelimitedthanwirenetworks.Soratecontrolbecomesespeciallyimportantfortransmittingmultimediaoverthewirelessdomains[1- … 相似文献
20.
INTRODUCTION Video multicasting over wireless local area net- work (WLAN) (IEEE Standard 802.11, 1997) enables the distribution of live or pre-recorded programs to many receivers efficiently. An example application is to redistribute TV programs or location-specific in- formation in hot spots such as airport. Users can watch their favorite TV programs on mobile devices while browsing the Internet. For enterprise applica- tions, an example is multicasting video of a lecture or trainin… 相似文献