基于模糊聚类和网格变形的自适应时-空差错掩盖方法

当视频传输中出现不能恢复的误码或丢包时,在接收端就要使用差错掩盖技术对损坏的视频进行掩藏。该文提出了一种基于模糊聚类和网格变形的自适应差错掩盖方法,使得错误恢复效果提高。该方法首先用基于时-空的模糊聚类块匹配方法补偿平移运动场景中的块丢失,然后如果检测出丢失块所在的空间有旋转、缩放等复杂运动,则用基于网格变形的方法进行补偿。实验结果表明其PSNR值比Luigi(2001)的BMA-MBW方法平均提高约1.5dB,比传统的基于块匹配的方法平均提高约3.5dB。     

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。     

一种基于HVS、模糊聚类和遗传算法的视频差错掩盖方法

当视频在传输过程中发生不可纠正的差错时,就要用差错掩盖的方法对丢失或差错的块进行掩盖。本文提出了一种基于模糊聚类和遗传算法的视频差错掩盖算法,首先,在确定适应度函数时,采用了一种适应人眼视觉系统(HVS: Human Visual System)的视频评价函数作为目标函数,其次,通过模糊聚类的方法同时综合多特征量得到差错块的相似块得到初始种群,然后利用GA的三个步骤:复制＼遗传＼交叉进行迭代地运算,直到最后得到满足条件的差错块的掩盖块。实验结果表明,其主客观效果比传统方法和基于一般GA算法的方法好。     

基于模糊聚类的空域视频差错掩盖

在视频图像的内容运动剧烈或者场景切换的情况下,解码图像出现的差错无法用时域上的信息加以恢复,利用当前解码帧内的空域相关性来进行差错掩盖就成为关键技术.本文从匹配特征矢量和块相似性统计指标出发,提出一种基于模糊聚类的空域差错掩盖的新方法.实验表明,与传统的块匹配和多方向插值掩盖方法相比,该方法改善了恢复图像的边缘细节,提高了重建图像的质量.     

基于人脸特征的自适应空域差错掩盖算法

针对在视频通信中,高压缩视频码流对通信信道中由于信道带宽、环境等影响出现的丢包和误码极为敏感,本文提出一种在解码端基于人脸检测的自适应空域差错掩盖算法,根据正确接收帧的人脸位置及人脸运动的趋势预测受损帧人脸的位置,对于受损帧人脸内五官区域的宏块采用水平双线性插值,对于背景区域宏块采用自适应多方向插值算法。实验结果表明与现有算法相比主客观质量都有所提高。     

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。     

基于H.264的改进时域误码掩盖算法

提出一种模式自适应的误码掩盖算法。对宏块进行误码掩盖时,对宏块的模式进行估计,选择最优的模式进行误码掩盖。这样可以近似地恢复了宏块运动矢量和编码模式,而不是通常算法中仅仅只恢复运动矢量。通过一定的实验测试,该算法在不同的序列和不同的丢包率均稳定的优于单一模式的误码掩盖算法。     

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。     

一种新的低复杂度基于变换域的图像差错掩 盖算法

针对图像视频在分组交换传输中的分组丢失问题，提出了一种低复杂度的、基于变换域的图像差错掩盖算法。在编码器端，采分级编码技术，根据其对图像质量影响的大小将数据分成具有不同传输优先级的两组；在解码器端、根据丢失图像块的性质，以及预测方法得到的阈值对其进行有效的差错掩盖。模拟结果显示，本算法有着更好的视觉质量以及更低的计算复杂度。     

基于多方向边界匹配的视频误码掩盖算法

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.     

Mode selection algorithms for enhanced spatiotemporal error concealment

Mode selection algorithms for spatiotemporal concealment of missing macroblocks (MBs) in a corrupted video stream are presented. The proposed algorithms employ the motion compensated temporal activity in the neighbourhood of each missing MB for switching between concealment methods. Results show gains of up to 4.6 dB for a 10% packet error rate relative to other mode selection methods     

用于多视视频加深度的错误隐藏算法

提出了一种针对多视视频加深度(MVD)的错误隐藏( EC)算法。算法充分利用MVD特有的深度 信息及当前丢失宏块周围正确解码的宏块信息,将丢失宏块分为3类不同属性的宏块。针对3类宏块的特 点,分别提出了基于候选运动矢量修正(CMVR)、基于深度的外边界匹配(DOBMA)以及自适应 权 值的EC(AWEC)等模式。实验表明,本文提出的算法在保证相同的视频主客观质量情况下, 能够快速有效地实现EC。     

一种低复杂度立体视频错误隐藏新方法

针对立体视频流传输中右视 点整帧丢失,提出 了一种低复杂度的错误隐藏算法。首先,为了高效地感知立体视频的时域质量和视点间质量 ,定义了时域相似尺度(TSM)、 视间相似尺度(ISM)的概念;将前一时刻右视点图像进行时域和视点间匹配,分别求取 其以像素为单位的TSM和 ISM映射图;然后,计算前一时刻右视点图像当前宏块的TSM和ISM值,通过比较得 到当前宏块的预测模式;最后,根据视频序列的时域一致性,将前一时刻右视点图像宏块 的预测模式作为丢失图像宏 块的预测模式,从而使用运动补偿预测(MCP)或者视差补偿预测(DCP )的方法恢复丢失信息。研究结果表明,与已有错误隐藏 算法相比,本文算法获得更好主客观视觉效果;同时与基于图像结构相似度(SSIM)的错误隐藏算法相比,在保持主观视觉质量情况下,错误隐藏时间节省20%左右。     

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.     

An effective GM/LM-based video error concealment

Error concealment (EC) techniques are often utilized at decoder side to improve reconstructed videos, in case of some information is lost during transmission on a wireless or band-width limited communication channel. In this paper, a global motion/local motion (GM/LM)-based error concealment method is proposed. First, the correct-macro-blocks (CMBs) are classified into global motion compensated MBs and local motion compensated MBs adaptively. Then, an erroneous MB (EMB) is classified into one of the three types: global motion MB (GMB), local motion MB (LMB), and global/local overlapping MB (GLMB) according to the MB type information in its neighbors. For the EMB with its type, GMB is recovered using the global motion vector (GMV). The EMB with its type LMB is recovered using the average motion vector information. And for the MB with its type GLMB, a recursive boundary matching strategy is utilized to search an optimal recovering motion vector. Experimental results show the effectiveness of the proposed GM/LM-based error concealment method.     

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.     

Proposed dynamic error control techniques for QoS improvement of wireless 3D video transmission

Error control techniques like error resilience (ER) and error concealment (EC) are efficient techniques to ameliorate the lost macroblocks (MBs) in the 3D video (3DV) communication system. In this paper, we propose efficient and adaptive hybrid ER‐EC algorithms for 3DV transmission over error‐prone wireless channels. At the encoder, adaptive preprocessing ER mechanisms are proposed through using the context adaptive variable length coding entropy, slice structured coding modes, and explicit flexible macroblock ordering mapping. They are used to assist the suggested EC techniques at the decoder to accurately reconstruct the erroneous MBs and frames. At the decoder, an efficient postprocessing EC technique with multiproposition methods is proposed to dynamically select the convenient EC hypothesis method based on the size of the lost MBs, the faulty view, and the frame type. It conceals the received erroneous MBs of intra‐encoded and inter‐encoded frames of the transmitted 3DV by exploiting the temporal, spatial, and inter‐view correlations among frames and views. To further improve the decoded 3DV quality, a weighted overlapping block motion and disparity compensation technique is used to reinforce the performance of the suggested ER‐EC techniques. Experimental results on various 3DV streams prove that the suggested techniques have considerably acceptable subjective and objective 3DV performance. They achieve an improved average peak signal‐to‐noise ratio gain by almost 2.85 dB compared to the conventional error control algorithms at a packet loss rate = 40%.     

面向HBP编码格式的立体视频B帧整帧丢失分层错误隐藏算法

针对分层B帧(HBP)编码格式的立体视频B帧整帧丢失的问题,该文分析了双视点视频中存在的视点间运动矢量相关性,提出一种分层错误隐藏算法。该算法与当前主流的方法有两大不同:一是该算法采用分级隐藏,根据B帧的重要性等级不同采用不同的错误隐藏方法;二是该算法考虑了相邻视点序列之间的宏块运动矢量相关性。实验表明,该算法的性能优于当前常用的H.264多视点视频整帧丢失错误隐藏方法。     

一种用于多视视频加深度联合编码的错误隐藏算法

ATM(AVC-based test model)测试模型实现了多视视频加深度(MVD)格式的联合编码,使得数据的压缩效率更高。然而,较高的压缩效率使得码流对传输错误非常敏感,极易产生错误扩散现象。针对ATM测试模型的编码顺序,提出一种用于MVD联合编码的错误隐藏算法。算法充分利用视点内、视点间及纹理视频与深度视频间的相关性,针对每个视点的不同特征提出了适应其视频特性的不同隐藏算法。实验表明,本文提出的算法可以在不增加算法复杂度的情况下,有效提高视频的主客观质量。