基于多方向自适应加权的空间错误隐藏算法

为了提高H.264/AVC压缩视频码流在无线信道传输过程中的抗误码性能,提出了一种基于多方向自适应加权的空间错误隐藏算法.该算法首先应用边缘算子检测受损宏块的相邻宏块信息,然后通过多方向自适应加权插值得到受损宏块像素近似值.实验表明,该算法相对传统空间错误隐藏算法,对于不同视频序列图像重构质量有很大的改善,具有较高的应用价值.     

一种改进的无线信道中压缩视频码流的错误隐藏算法

无线信道传输环境不稳定,容易产生随机和突发误码,这对码流相关性很强的压缩视频信号将产生很恶劣的影响,并将在解码端扩散.本文分析了传统错误隐藏算法的原理和局限性,针对信源语义错误隐藏技术计算量大、可能不能得到目标片的缺点,提出一种新的算法,根据无线信道误码的特点,产生与信道情况相关的候选片,利用压缩感知技术的模糊匹配特性,用解析方式得到目标片,并可在此基础上对信道恶劣的情况提出重传建议,计算简单,客观恢复质量较好.     

Frame Error Concealment Using Pixel Correlation in Overlapped Motion Compensation Regions

In low bit‐rate video transmission, the payload of a single packet can often contain a whole coded frame due to the high compression ratio in both spatial and temporal domains of most modern video coders. Thus, the loss of a single packet not only causes the loss of a whole frame, but also produces error propagation into subsequent frames. In this paper, we propose a novel whole frame error concealment algorithm which reconstructs the first of the subsequent frames instead of the current lost frame to suppress the effects of error propagation. In the proposed algorithm, we impose a constraint which uses side match distortion (SMD) and overlapped region difference (ORD) to estimate motion vectors between the target reconstructed frame and its reference frame. SMD measures the spatial smoothness connection between a block and its neighboring blocks. ORD is defined as the difference between the correlated pixels which are predicted from one reference pixel. Experimental results show that the proposed algorithm effectively suppresses error propagation and significantly outperforms other conventional techniques in terms of both peak signal‐to‐noise ratio performance and subjective visual quality.     

基于纹理方向预测的空域差错隐藏方案

在差错信道中传输视频压缩码流时,容易发生视频数据的损坏或丢失,这样不仅会对当前的视频帧产生影响,而且差错会蔓延到后续视频帧。I帧出错时的影响尤为严重。针对这一问题,本文在对H.264标准进行研究的基础上,对一种空域差错隐藏算法——纹理方向法进行了改进,结果表明,这种方法达到了较好的隐藏效果,改善了图像的主观质量。     

视频通信中基于不同频率成分的空域差错消隐方法

在视频通信中，由于信道噪声的影响，致使视频图象中经常出现比特差错以及块和宏块差错，它们严重地影响着视频的质量，同时由于基于检错重发的机制不能很好地满足实时的要求，目前许多人提出了时域、空域、频域以及它们的联合差错消除方法，但这些方法比较复杂，为了利用简单可行的方法，在校正错误的同时，并能满足实时传输处理的要求，从而提出了一种基于不同频率成分的空域误码隐匿和恢复方法，该方法利用马尔科夫随机场描述了像素之间以及像素块之间的相关性，并以此来确定用以恢复误码区域的邻域及其误码块中边缘像素的邻域，再根据人眼视觉,地误码区域的高频与低频部分分别利用不同的策略来先预测，后恢复，并在均方误差最的差错处理能力和良好的差错恢复性能。     

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。     

Spatial error concealment: A novel exemplar-based approach using segmentation

In this paper, the problem of spatial error concealment for real-time applications is addressed. The proposed method can be categorized in exemplar-based error concealment approaches. In this category, a patch of corrupted pixels are replaced by another patch of the image that contains correct pixels. For splitting the erroneous block to different patches, a novel context-dependent exemplar-based algorithm based on a previously proposed segmentation method is proposed. The capability of the proposed method for concealment in diverse image regions is depicted. Our detailed conducted experiments show that the proposed method outperforms the state-of-the-art spatial error concealment methods in terms of output quality.     

基于可变尺寸块运动矢量恢复的H.264时域差错掩盖算法

针对H.264帧间预测编码的新特点,提出了一种基于可变尺寸块运动矢量恢复的时域差错掩盖算法。该算法首先利用相邻宏块编码模式的相关性,根据周围宏块的编码模式判断受损宏块的编码模式及运动矢量恢复的宏块划分方式,分别对各个划分的子块进行运动矢量的恢复;然后利用相邻块运动矢量参考帧的相关性,根据相邻块运动矢量的参考帧确定匹配使用的参考帧;最后采用边缘失真匹配方法恢复运动矢量。实验结果表明,该算法同传统的差错掩盖算法相比,由于支持不同尺寸块运动矢量的恢复,因此,算法对差错信号能够获得更好的恢复效果。     

视频压缩编码的差错复原技术

在无线移动信道和因特网等环境下的压缩视频传输业务,信道传输差错不但严重影响业务质量,甚至会导致整个视频通信完全失效,因此差错复原技术就成为易发生差错信道下视频编码的重要组成部分。在Ｈ．２６３＾＋,Ｈ．２６３＾＋和ＭＰＥＧ－４等视频编码标准中均采用了若干差错复原技术或工具。该文对目前各种新的视频编码标准中所应用的一些差错复原技术,如重同步、数据分割、可逆变长编码、参数图象选择、差错掩盖等的内容、原理     

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.