基于自适应叠加的H.264时域错误隐藏算法

为了减小视频传输错误对解码端重建视频质量的影响,根据H.264标准的特点,提出一种基于多模式自适应叠加的时域错误隐藏算法。该算法以不同分割模式对丢失宏块进行4次隐藏,得到4个隐藏块,并计算各模式的绝对帧差和,使该值最小的2个隐藏块自适应加权叠加作为最终的替代块。仿真结果表明,与传统方法相比,该算法的错误隐藏性能得到较大提高。     

Content-based hybrid error concealment approach for packet video communication over the noisy channels

Video compression makes the encoded video stream more vulnerable to the channel errors so that, the quality of the received video is exposed to severe degradation when the compressed video is transmitted over the error-prone environments. Therefore, it is necessary to apply error concealment (EC) techniques in the decoder to improve the quality of the received video. In this regard, an Adaptive Content-based EC Approach (ACBECA) is proposed in this paper, which exploits both the spatial and temporal correlations within the video sequences for the EC purpose. The proposed approach adaptively utilizes two EC techniques, including new spatial-temporal error concealment (STEC) technique, and a temporal error concealment (TEC) technique, to recover the lost regions of the frame. The STEC technique proposed in this paper is established on the basis of non-Local Means concept and tries to recover each lost macroblock (MB) as the weighted average of the similar MBs in the reference frame, whereas the TEC technique recovers the motion vector of the lost MB adaptively by analyzing the behavior of the MB in the frame. The decision on temporally or spatially reconstructing the degraded frames is made dynamically according to the content of the degraded frame (i.e., structure or texture), type of the error and also block loss rate (BLR). Compared with the state-of-the-art EC techniques, the simulation results indicate the superiority of the ACBECA in terms of both the objective and subjective quality assessments.

     

RVLC decoding scheme for improved data recovery in MPEG-4 video coding standard

In this paper, we present a low-complexity ‘reversible variable length code’ (RVLC) decoding scheme for MPEG-4 video that recovers more blocks and sometimes more macroblocks (MBs) from error propagation region of corrupted video packets, as compared to the MPEG-4 scheme. The remaining blocks and MBs are concealed. Simulation studies have been carried out to show that the proposed scheme achieves better data recovery, both in terms of peak-signal-to-noise ratio (PSNR) and perceptual quality. In addition, we present more conditions for error detection than those suggested in MPEG-4, discuss properties of error propagation in corrupted video packets, and provide the RVLC codeword structure. The use of RVLC code structure will enable the decoding in both directions by using only one code table, instead of separate tables used for forward and backward decoding. Since the scheme is purely decoder based, the compliance with the standard is fully maintained. It is very simple for the decoder to keep track of the additional blocks/MBs recovered by the proposed scheme. Therefore, the data recovery scheme suggested in MPEG-4 can still be used as default scheme.     

Region-based error concealment of right-view frames for stereoscopic video transmission

Transmission of stereoscopic video stream through error-prone wireless channels results in the loss of blocks. In this paper, we propose a region-based error concealment method that exploits encoding modes, inter-view and intra-view correlations of stereoscopic video sequences. Based on the statistical analysis of the encoding modes of the surrounding macroblocks (MBs) and of the spatially corresponding MB in the neighboring frame, the lost MBs are classified into three types: (1) smooth MBs, (2) regular motion MBs and (3) irregular motion MBs. Following the classification, corresponding operations, including direct replacement, quarter-pixel motion and disparity compensation, and bilateral error concealment with adjustable weights, are applied to reconstruct the smooth MBs, regular motion MBs and irregular motion MBs, respectively. Experimental results show that the proposed method outperforms other existing error concealment methods for stereoscopic video transmission in terms of both objective and subjective evaluations.     

基于纹理检测的视频序列误差掩盖

文章提出了一种新的误差掩盖(ErrorConcealment)算法,作为在解码器端的后处理工具去解决视频序列在传输过程中产生的块及其运动矢量同时丢失的问题。笔者利用LOG算子去对丢失块周围的块进行纹理检测,取所有属于纹理块的运动矢量的平均值,作为丢失运动矢量的估计。仿真结果表明对不同块丢失率或不同视频序列,此算法都能比传统的方法恢复出质量更高的图像。     

低复杂度空域错误隐藏算法

在无线网等不可靠信道传输视频中,针对包含边缘信息的宏块丢失带来的错误,提出了一种低复杂度的空间域错误隐藏算法,该算法根据周围已经接收到的宏块特征,估算丢失宏块中边缘方向,并按照边缘方向使用周围临近像素值进行插值,恢复出包含边缘的宏块;在插值过程中提出并采用了一种快捷的方向插值法。实验结果表明,该算法能有效地掩盖丢失宏块,比常规方法具有更好的掩盖效果与实时性。     

基于数据嵌入的H.264/AVC错误隐藏算法

为了改进和完善H.264/AVC的错误隐藏性能,提出了一种基于数据嵌入的错误隐藏算法。算法在编码端提取能用于错误隐藏的特征数据,用奇偶嵌入法,通过宏块交织的方式将数据嵌入到下一帧中。当解码器没有正确接收到宏块时,在该宏块下一帧相应位置提取特征信息进行错误隐藏。实验结果表明,在同等应用环境下,与JM10自带的错误隐藏方法相比,此方案错误隐藏的主观和客观效果均有显著提高。     

H.264高清视频解码实时错误掩盖算法

针对IP网络丢包条件下的H.264高清视频实时解码问题,分析高清视频码流的特点,提出一种实时错误掩盖算法。该算法利用丢失片的边缘宏块信息,以垂直距离为权值加权平均预测得到错误宏块的运动矢量,进而完成错误掩盖。实验表明,与Joint模型中的错误掩盖算法相比,该算法提升了重建图像的主观质量和客观质量,计算复杂度较低,错误掩盖效果较好,适用于高清实时解码。     

基于多模式叠加的H.264时域隐藏算法

为在高误码环境下提高视频通信中重建图像的质量,根据最新H.264标准的特点,提出了一种基于多模式叠加的时域错误隐藏算法。该算法以不同的模式对丢失宏块进行4次掩盖,得到4个隐藏块,以各隐藏块的加权和作为丢失宏块的最终替代块。仿真结果表明,由于利用了宏块模式信息,该算法在不同测试序列及丢包率下的性能均优于传统叠加算法,显著提高了掩盖效果。     

基于H.263技术的差错掩盖和交互差错修正技术

随着通信和计算机技术的发展，基于不可靠网络的视频图象的通信受到了越来越广泛的应用。因此，视频传输中的差错控制技术和差错掩盖技术也显得越来越重要。本文提出了一种精确的差错恢复方案．即将精确差错跟踪和差错掩盖技术相结合的方案，不仅通过帧内编码刷新技术终止了差错的继续传播，而且利用图象和视频特性，在解码器端采
采用差错掩盖技术恢复受损图象。通过在H．263编解系统中的实验表明．这种方法对改善出现差错的视频信号非常有效．     

基于DCT系数的自适应误码掩盖算法

提出一种改进的误码掩盖算法,即自适应地选择加权插值和区域匹配方法恢复丢失块.不同于以往只利用平滑性的误码掩盖算法,该算法利用平滑信息和纹理信息,在可用的相邻宏块中基于DCT系数计算能量函数总和,自动分析图像的平滑性和纹理性,然后自适应地选择加权插值或区域匹配的结果恢复丢失块.该算法已在H.264的参考软件JM86上进行实验.实验结果表明,与H.264中只采用加权插值或只采用区域匹配相比,该算法能取得较好的峰值信噪比(PSNR)和主观质量.     

Error resilient video coding with priority data classification using H.264 flexible macroblock ordering

Flexible macroblock ordering (FMO) is a new error resilience feature in the H.264 (MPEG-4 part 10) video coding standard. The paper exploits FMO to offer a new classification algorithm for prioritised video transmission. Instead of using the default mapping structures of FMO, an optimisation algorithm in which the more important macroblocks (MBs) are categorised in a separate slice group (SG), which corresponds to high-priority packets for transmission, is proposed. The importance of each MB is determined based on its eventual influence on picture quality. This is assessed by considering the fact that the successful transmission of an MB not only enhances the quality of the associated pixels, but also improves the quality of its adjacent lost MBs by improving the efficiency of error concealment. It is assumed that the network can offer a prioritised service for successful transmission of the high-priority SG. Based on this, a vulnerability factor for each MB is determined, and a certain proportion of high-vulnerability MBs at each frame to limit the impact of temporal error propagation is intra-updated. It is shown, where the proposed mapping algorithm outperforms the default mappings of the H.264 codec, that this prioritised transmission will improve the subjective and objective video quality in situations with a high probability of transmission errors.     

Decision trees for error concealment in video decoding

When macro-blocks are lost in a video decoder such as MPEG-2, the decoder can try to conceal the error by estimating or interpolating the missing area. Many different methods for this type of post-processing concealment have been proposed, operating in the spatial, frequency, or temporal domains, or some hybrid combination of them. In this paper, we show how the use of a decision tree that can adaptively choose among several different error concealment methods can outperform each single method. We also propose two promising new methods for temporal error concealment.     

Error detection based on MB types

This paper proposes a method of error detection based on macroblock （MB） types for video transmission. For decoded inter MBs, the absolute values of received residues are accumulated. At the same time, the intra textural complexity of the current MB is estimated by that of the motion compensated reference block. We compare the inter residue with the intra textural complexity. If the inter residue is larger than the intra textural complexity by a predefined threshold, the MB is considered to be erroneous and errors are concealed. For decoded intra MBs, the connective smoothness of the current MB with neighboring MBs is tested to find erroneous MBs. Simulation results show that the new method can remove those seriously-corrupted MBs efficiently. Combined with error concealment, the new method improves the recovered quality at the decoder by about 0.5--1 dB.     

增强无线视频图像传输差错恢复能力的方法研究

对无线网络环境下视频图像的鲁棒性传输问题进行了研究，提出了一种增强视频图像传输差错恢复能力的新方法。在编码器端采用基于DCT(discrete cosine transform)矩阵系数的快速分类算法提取图像区域分类特征与再同步信息等构成指示信息，并用考虑量化误差后改进的DCT系数强制奇偶修改方法将其嵌入到图像码流中，用于解码器端视频图像序列的差错检测、再同步和差错恢复，以此增强基于H．263 的视频图像传输的鲁棒性。实验结果表明，此方法可以有效地改善标准编解码器的传输质量，不额外增加信源传输码字，计算成本较小。     

RETRACTED ARTICLE: Edge-Oriented Spatial Interpolation for Error Concealment of Consecutive Blocks

This paper proposes a low-complexity spatial-domain error concealment (EC) algorithm for recovering consecutive blocks error in still images or intra-coded (I) frames of video sequences. The proposed algorithm works with the following steps. Firstly the Sobel operator is performed on the top and bottom adjacent pixels to detect the most probable edge direction of current block area. After that one-dimensional (1-D) matching is used on the available block boundaries. Displacement between edge direction candidate and most probable edge direction is taken into consideration as an important factor to improve stability of 1-D boundary matching. Then the corrupted pixels are recovered by linear weighting interpolation along the estimated edge direction. Finally the interpolated values are merged to get last recovered picture. Simulation results demonstrate that the proposed algorithms obtain good subjective quality and higher PSNR than the methods in literatures for most images.     

基于边界匹配的增强多权重差错掩盖方法研究

提出了一种基于边界匹配的增强多权重差错掩盖算法,通过受损宏块周围时空域相邻宏块的相关信息在增强候选运动矢量集中进行运动矢量选取,采用多权重的边界匹配方法使之在物体边界处能够获得更准确的运动矢量,并专门对连续图像片丢失或整帧丢失的情况进行时域掩盖处理。基于H．26L的仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。     

Video Error Concealment Using Spatio-Temporal Boundary Matching and Partial Differential Equation

Error concealment techniques are very important for video communication since compressed video sequences may be corrupted or lost when transmitted over error-prone networks. In this paper, we propose a novel two-stage error concealment scheme for erroneously received video sequences. In the first stage, we propose a novel spatio-temporal boundary matching algorithm (STBMA) to reconstruct the lost motion vectors (MV). A well defined cost function is introduced which exploits both spatial and temporal smoothness properties of video signals. By minimizing the cost function, the MV of each lost macroblock (MB) is recovered and the corresponding reference MB in the reference frame is obtained using this MV. In the second stage, instead of directly copying the reference MB as the final recovered pixel values, we use a novel partial differential equation (PDE) based algorithm to refine the reconstruction. We minimize, in a weighted manner, the difference between the gradient field of the reconstructed MB in current frame and that of the reference MB in the reference frame under given boundary condition. A weighting factor is used to control the regulation level according to the local blockiness degree. With this algorithm, the annoying blocking artifacts are effectively reduced while the structures of the reference MB are well preserved. Compared with the error concealment feature implemented in the H.264 reference software, our algorithm is able to achieve significantly higher PSNR as well as better visual quality.     

Video error concealment scheme based on tensor model

Multimedia Tools and Applications - Since compressed video sequences may be corrupted or lost when transmitted over error-prone networks, error concealment techniques are very important for video...     

基于边界匹配的增强多权重差错掩盖方法研究*

提出了一种基于边界匹配的增强多权重差错掩盖算法,通过受损宏块周围时空域相邻宏块的相关信息在增强候选运动矢量集中进行运动矢量选取,采用多权重的边界匹配方法使之在物体边界处能够获得更准确的运动矢量,并专门对连续图像片丢失或整帧丢失的情况进行时域掩盖处理。基于H.26L的仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。