一种基于多参考帧的时域误码掩盖算法

视频压缩码流对于信道误码十分敏感,可导致重建图像质量严重下降,在接收端就要使用误码掩盖技术对损坏的视频进行掩藏。文中提出一种基于多参考帧的时域误码掩盖算法,首先计算受损宏块的相邻块的运动矢量的均值,然后遍历所有参考帧得到待选的误码掩盖宏块,最后用外边界匹配算法找出替代受损宏块的宏块。研究结果表明,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。     

H.264视频误码掩盖综述

在无线网络和因特网上传输视频，误码掩盖的问题越来越重要。回顾了文献中介绍的误码掩盖的方法。误码掩盖后处理利用图像和视频信号的相关特性，在解码端对丢失区域进行掩盖，并总结了空域、时域，以及时空结合的误码掩盖方法。     

一种整帧丢失时的视频差错掩盖算法

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,当网络传输中数据包丢失时,通常对应于一整帧图像内容的丢失。为了恢复丢失帧,提出了一种针对整帧图像丢失时的基于运动向量外推法的空时域相结合的差错掩盖算法。试验结果表明,该算法不仅能够恢复整个丢失帧,而且在主观上与客观上其掩盖效果均优于传统的掩盖算法。     

一种新颖实用的交互式视频抗误码方法

本文提出一种新颖的交互式视频抗误码方法.首先,分析了块匹配运动补偿编码方法产生时域误码扩散的机理,然后,相应地提出了一种新颖的误码掩盖和防止误码扩散联合方法.实验结果表明,使用本文提出的交互式视频抗误码方法能够有效地抑制和防止误码的扩散,保证了恢复视频质量.另外,该算法与H.263+标准兼容,具有实用价值.     

低速率视频传输的抗误码技术

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。     

基于无线H．264时域误码掩盖算法的改进

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.     

整帧丢失时基于多帧参考的差错掩盖算法

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。     

H．264后处理误码掩盖技术

数字视频通信中往往会由于信道不理想等原因而产生误码,而且误码在空间和时间上的扩散会导致重建图像质量不同程度的下降.而误码掩盖技术就是用来改进重建视频质量的重要方法之一.文章论述了国内外误码掩盖技术的现状及其典型算法,分析了误码掩盖技术的应用范围和性能,最后指出误码掩盖技术的发展前景.     

视频通信抗误码方法研究的新进展

本文比较全面地总结了视频通信中抗误码方法的研究及其新进展.首先,详细评述了结合信源特点的前向差错控制、码流变换、解码端的误码掩盖和防误码扩散等视频抗误码新方法;然后,介绍视频编码标准H.263+/H.263++和MPEG-4中提出的抗误码算法;接下来,讨论多种视频抗误码系统的设计方案;最后,对视频抗误码今后研究的重点和方向提出了展望.     

视频通信中空域和时域误码掩盖方法的研究

随着多媒体通信技术的不断发展,在无线网络和因特网上进行视频传输显得尤为迫切。但是在传输过程中,误码几乎是不可避免的。文中从空域和时域出发,回顾了国外主流视频通信误码掩盖技术,分析了它们的应用范围和性能,并指出了其发展前景。     

Error concealment techniques for digital TV

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.     

一种基于快速搜索的视频时域差错隐藏算法

为了克服视频传输中因传输差错引起的视频质量下降,提出一种基于快速搜索的边框匹配时域隐藏算法(CSBM)。该算法针对时域差错隐藏的运动矢量恢复问题,利用边框匹配算法改善被恢复的物体边缘模糊的情况;采用基于中心偏置的快速搜索样式得到最小边界匹配差值的候选运动矢量,减少了解码器差错恢复的计算复杂度。实验结果显示,针对不同性质的序列,该算法与边界匹配算法(SMA)、棱形搜索的边界匹配法(DSSM)等典型差错隐藏方法相比,平均搜索点数可减少12.5~19个点,亮度分量的峰值信噪比(PSNR)能改善0.93~1.55 dB,证明该算法能获得更好的差错隐藏效果,并减少了运算量。     

High‐Performance Spatial and Temporal Error‐Concealment Algorithms for Block‐Based Video Coding Techniques

A compressed video bitstream is sensitive to errors that may severely degrade the reconstructed images even when the bit error rate is small. One approach to combat the impact of such errors is the use of error concealment at the decoder without increasing the bit rate or changing the encoder. For spatial‐error concealment, we propose a method featuring edge continuity and texture preservation as well as low computation to reconstruct more visually acceptable images. Aiming at temporal error concealment, we propose a two‐step algorithm based on block matching principles in which the assumption of smooth and uniform motion for some adjacent blocks is adopted. As simulation results show, the proposed spatial and temporal methods provide better reconstruction quality for damaged images than other methods.     

Multiframe error concealment for MPEG-coded video delivery over error-prone networks

Compressed video sequences are very vulnerable to channel disturbances when they are transmitted through an unreliable medium such as a wireless channel. Transmission errors not only corrupt the current decoded frame, but they may also propagate to succeeding frames. A number of post-processing error concealment (ECN) methods that exploit the spatial and/or temporal redundancy in the video signal have been proposed to combat channel disturbances. Although these approaches can effectively conceal lost or erroneous macroblocks (MBs), all of them only consider spatial and/or temporal correlation in a single frame (the corrupted one), which limits their ability to obtain an optimal recovery. Since the error propagates to the next few motion-compensated frames in the presence of lost MBs in an I or P frame, error concealment should simultaneously minimize the errors not only in the current decoded frame but also in the succeeding B and P frames that depend on the corrupted frame. We propose a novel multiframe recovery principle which analyzes the propagation of a lost MB into succeeding frames. Then, MPEG-compatible spatial and temporal error concealment approaches using this multiframe recovery principle are proposed, where the lost MBs are recovered in such a way that the error propagation is minimized.     

Motion field interpolation for temporal error concealment

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     

Error concealment of multi-view video sequences using inter-view and intra-view correlations

An efficient error concealment algorithm for multi-view video sequences is proposed in this work. First, we develop three concealment modes: temporal bilateral error concealment (TBEC), inter-view bilateral error concealment (IBEC), and multi-hypothesis error concealment (MHEC). TBEC and IBEC, respectively, exploit intra-view and inter-view correlations in multi-view video sequences to reconstruct an erroneous block. MHEC finds a few candidate blocks based on the block matching principle and combines them for the concealment. We then propose a mode selection scheme, which chooses one of the three modes adaptively to provide reliable and accurate concealment results. Simulation results demonstrate that the proposed algorithm can protect the quality of reconstructed videos effectively even in severe error conditions.     

一种基于H.264\AVC的差错隐藏方法

为提高在视频通信中重建图像的质量,针对H.264＼AVC视频编码标准的新特性,提出了一种新的基于H.264＼AVC的差错隐藏方法.受损的帧或者宏块导致的解码错误会在时间上和空间上扩散,该算法充分利用了基于模型的编码和宏块的空间、时间相关性来对受损帧或者宏块进行恢复.仿真结果表明这种方法在不增加比特率的情况下,使峰值信噪比值得到了提高.     

Reference picture selection with decreased temporal dependency for HEVC error resilience

The high level of compression efficiency achieved by the High-Efficiency Video Coding standard (HEVC) decreases the robustness of the encoded bitstreams. This increased susceptibility to network errors leads to end video quality degradation. Moreover, due to the high computational complexity of HEVC, high-resolution video transmission with time constraints over hostile channels such as wireless networks becomes more challenging. This paper proposes a reference picture selection-based error-resilient method to reduce the temporal error propagation due to high-trip delay and frame-copy concealment error. First, the encoder selects the reference pictures based on the error status received from the feedback channel, taking into consideration the Rate-Distortion-Optimization (RDO). Second, the temporal information mismatch prediction resulting from the error concealment is reduced by decreasing the temporal dependency between adjacent frames based on new motion-estimation tools. Results show a PSNR gain of about 6.13 dB, 5.20 dB and 4.72 dB for 1080p, 720p and 480p resolutions respectively.