共查询到19条相似文献,搜索用时 109 毫秒
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视频通信中的错误掩盖方法研究 总被引:2,自引:0,他引:2
误码几乎是不可避免出现在数字视频通信中,其在空间和时间上的扩散对重建图像质量有着不良影响,错误掩盖技术即是用来解决这个问题的重要途径之一。文章论述了国内外错误掩盖技术的现状及其典型算法,分析了它们的应用范围和性能,并指出了其发展前景。 相似文献
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基于多方向边界匹配的视频误码掩盖算法 总被引:1,自引:1,他引:0
视频压缩码流对于信道误码十分敏感,可能导致重建图像质量严重下降.误码掩盖技术利用图像在时间和空间上的相关性,可以有效地降低误码对视频图像的影响.文中提出了一种基于多方向边界匹配的时域误码掩盖算法.该算法能更精确地恢复错误宏块的运动矢量,从而获得比传统的时域掩盖算法更好的视频质量. 相似文献
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误码掩盖是在无线信道进行低速率视频传输的一种抗误码技术。本文在比较和分析了现有几种误码掩盖方法优劣势后,提出了一种混合误码掩盖法。该算法在没有过多增加解码端运算复杂度的同时,大大提高了恢复图像的质量。 相似文献
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H.264视频流采用熵编码,因此码流中很小的传输错误可能造成接收端码流质量的急剧下降。因此误码掩盖技术是近年来值得研究的课题。本文分析了几种混合的误码掩盖方法,以及基于数据隐藏的误码掩盖方法。数据隐藏方法在编码端提取当前帧的重要数据并嵌入到参考帧;解码端,若有损宏块的重要数据能够被正确的提取,则利用提取到的重要数据来掩盖误码。本文最后提出数据隐藏的发展方向。 相似文献
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为解决传统H.264时域误码掩盖算法中丢失块的相邻运动矢量在无线环境下极易丢失的问题,结合部分误码掩盖算法研究成果,提出了一种利用相邻参考帧和丢失块相邻运动矢量,运用投影加权的方法估计出最优丢失块运动矢量用于误码补偿的改进误码掩盖算法.实验证明,运用改进算法掩盖后的图像质量有所提高,并且抑制了误码的错误积累和扩散,具有一定实际应用意义. 相似文献
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压缩视频对于信道误码十分敏感,可导致重组视频的质量严重下降。在低码率的情况下,当网络传输中出现数据包丢失的情况时,通常对应于一整帧图像内容的丢失。为此本文提出了两种针对整帧图像丢失的差错掩盖算法一基于多帧参考的差错掩盖算法。研究结果表明,该算法不仅能够恢复整个丢失帧,而且其掩盖效果比传统的掩盖算法更好。 相似文献
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1 IntroductionWiththerapidlydevelopmentofmultimediacommunicationtechnology ,theH .2 6 1 ,MPEG 1andMPEG 2recommendationshavebeenestab lishedbytherelevantorganizationsofITU TorISOinthepastyears.Thesestandardsprovidethetoolsforimagestoreortransmissionatthehigher… 相似文献
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We address the problems of channel estimation and optimal training sequence design for multiple-input multiple-output systems over flat fading channels in the presence of colored interference. In practice, knowledge of the unknown channel is often obtained by sending known training symbols to the receiver. During the training period, we obtain the best linear unbiased estimates of the channel parameters based on the received training block. We determine the optimal training sequence set that minimizes the mean square error of the channel estimator under a total transmit power constraint. In order to obtain the advantage of the optimal training sequence design, long-term statistics of the interference correlation are needed at the transmitter. Hence, this information needs to be estimated at the receiver and fed back to the transmitter. Obviously it is desirable that only a minimal amount of information needs to be fed back from the receiver to gain the advantage in reducing the estimation error of the short-term channel fading parameters. We develop such a feedback strategy in this paper. 相似文献
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Motion field interpolation for temporal error concealment 总被引:4,自引:0,他引:4
Al-Mualla M.E. Canagarajah C.N. Bull D.R. 《Vision, Image and Signal Processing, IEE Proceedings -》2000,147(5):445-453
When transmitted over practical communication channels, compressed video can suffer severe degradation. One approach to combat the effect of channel errors is error concealment. It is an attractive choice because it does not increase the bit rate, it does not require any modifications to the encoder, it does not introduce any delays and it can be applied in almost any application. Conventional temporal concealment techniques estimate one concealment displacement for the whole damaged block and then use translational displacement compensation to conceal the block from a reference frame. The main problem with such techniques is that incorrect estimation of the concealment displacement can lead to poor concealment of the whole or most of the block. Two novel temporal concealment techniques are presented. In the first technique, motion field interpolation is used to estimate one concealment displacement per pel of the damaged block and then each pel is concealed individually. In this case, incorrect estimation of a concealment displacement will only affect the corresponding pel. On a block level this may affect few pels rather than the entire block. In the second technique, multi-hypothesis motion compensation is used to combine the first technique with a boundary matching temporal concealment technique to obtain a more robust performance. Simulation results, within both an isolated error propagation environment and an H.263 codec, show the superior subjective and objective performance of the proposed techniques when compared with conventional temporal concealment techniques 相似文献
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Weerackody V. Reichl W. Potamianos A. 《Wireless Communications, IEEE Transactions on》2002,1(2):282-291
Future wireless multimedia terminals will have a variety of applications that require speech recognition capabilities. We consider a robust distributed speech recognition system where representative parameters of the speech signal are extracted at the wireless terminal and transmitted to a centralized automatic speech recognition (ASR) server. We propose two unequal error protection schemes for the ASR bit stream and demonstrate the satisfactory performance of these schemes for typical wireless cellular channels. In addition, a "soft-feature" error concealment strategy is introduced at the ASR server that uses "soft-outputs" from the channel decoder to compute the marginal distribution of only the reliable features during likelihood computation at the speech recognizer. This soft-feature error concealment technique reduces the ASR error rate by more than a factor of 2.5 for certain channels. Also considered is a channel decoding technique with source information that improves ASR performance 相似文献
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Jae-Won Suh Yo-Sung Ho 《Broadcasting, IEEE Transactions on》2002,48(4):299-306
Compressed video bitstreams are intended for real-time transmission over communication networks. Most of the video coding standards employ the temporal and spatial prediction structure to reduce the transmitted video data. Therefore, the coded video bitstreams are highly sensitive to information loss and channel errors. Even a single bit error can lead to disastrous quality degradation in both time and space. This quality deterioration is exacerbated when no error resilient coding mechanism is employed to protect coded video data against the error prone environments. Error concealment is a data recovery technique that enables the decoder to conceal effects of transmission errors by predicting the lost or corrupted video data from the previously reconstructed error-free information. Motion vector recovery and motion compensation with the estimated motion vector is a good approach to conceal the corrupted macroblock data. In this paper, we develop various error concealment algorithms based on motion vector recovery, and compare their performances to those of conventional error concealment methods. 相似文献
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