图像传输中多描述编码与差错隐藏的综合应用

多描述编码和后处理差错隐藏是差错复原的两种主要技术,通常它们是分别进行研究的,然而,只有较少描述用于重构图像时不能得到满意的图像。本文提出一种多描述编码与差错隐藏相结合的差错复原算法,仿真实验验证了该算法的有效性。     

H.264的差错控制与错误隐藏技术研究

针对无线应用中的传输错误和IP网络拥塞导致的视频数据包丢失,H.264采用了一系列的技术。介绍了H.264所使用的差错控制和错误隐藏技术,重点讨论了基于灵活宏块重排（Flexible Macroblock Ordering,FMO）的差错控制技术,及基于整帧丢失的帧拷贝（Frame Copy）和运动矢量拷贝（Motion Copy）错误隐藏技术和基于宏块丢失的帧内隐藏和帧间隐藏技术。在此基础上,利用ITU-T的误码模型（Error Pattern）对H.264的差错隐藏的性能进行了仿真,并对错误隐藏的效果进行了定量分析。     

全局运动补偿技术在形状信息错误隐藏中研究

深入研究MPEG-4的形状编码技术和视频图像帧的编码方式,参照全局运动补偿技术,在图像形状信息全部丢失、部分丢失信息变化复杂的情况下,提出一种基于全局运动补偿的前向错误隐藏方法对出现传输错误的图像进行恢复。通过与Cheng方法对比仿真实验证明该方法取得很好的恢复效果,尤其是对象形状信息全部丢失时。     

内容指导的自适应时域错误隐藏算法

为了减小视频传输中的错误对解码端重建视频质量的影响,提出了一种使用于H.264的基于内容的自适应时域错误隐藏算法。该算法首先对受损块邻域进行边缘检测,通过对边缘信息的进一步分析来对受损块的宏块模式进行估计,然后根据估计的宏块模式对受损块进行重建。实验表明,该算法能更好地适应丢失块内存在运动目标的情形,差错隐藏效果明显。     

基于自适应块尺寸的H.264时域错误隐藏算法

为提高在视频通信中重建图像质量,充分利用运动矢量的空间相关性、相邻宏块的编码模式信息,提出了一种新的H.264时域错误隐藏算法。该算法根据误码块周围的邻块模式,自适应决定隐藏块的尺寸;对于每个尺寸块,都从多个候选运动矢量集合中选取使外边界对应像素差值最小的运动矢量;并利用运动估计技术更精确地恢复丢失宏块的运动矢量,从而提高所恢复视频信号的质量。实验结果表明：对于不同运动类型序列和不同宏块丢失率,该算法不仅计算量较小,而且恢复后的图像质量均优于传统的时域错误隐藏算法。     

一种基于对象几何形状的视频抗误码方法

针对压缩视频流中的误码,提出了一种新颖的基于对象几何形状的视频抗误码方法.首先,在编码端通过比较帧间编码帧内邻近宏块的运动向量差异获得粗略的对象几何形状信息,以对象标示图表示;再把它以与标准码流兼容的方式嵌入到压缩码流里去;最后,在解码端利用它帮助精确的构造错误宏块的运动向量.试验结果表明,该方法对于即使大量连续slice出错的情况仍能获得比较好的掩盖效果,而增加的运算复杂度和传输负载量都不大.     

基于内容的无线视频误码隐藏技术仿真

仿真了基于内容的误码隐藏技术,分析了各种技术的性能,最后给出了在实际的通信系统中如何选择合适的误码隐藏技术的结论,即误码隐藏技术必须根据视频特征和实际应用来决定采用何种技术.     

论我国“亲亲相隐”制度的现代化

“亲亲相隐”制度无论是在我国古代还是在西方国家都是一项重要的法律制度,当代西方许多国家还普遍存在这一制度,而我国立法中对该制度的规定并不完善.改革现行立法,确定“亲亲相隐”的适用范围及例外,符合人道主义精神和现代立法的发展趋势.     

Performance evaluation of enhanced error correction algorithms for efficient wireless 3D video communication systems

In the Three‐Dimensional Multi‐View Video (3D MVV) coding prediction structure, the coded bit‐streams may be dropped down due to error transmissions. So, it is compulsory to recover the corrupted Macro‐Blocks (MBs) at the decoder utilizing efficient Error Concealment (EC) post‐processing techniques. The EC methods exploit the temporal, inter‐view, and spatial matching among 3D MVV views and frames without any alterations in the encoder software or hardware or in the transmission rate. They retrieve the Disparity Vectors (DVs) and Motion Vectors (MVs) of the erroneous MBs. To enhance the received 3D MVV quality, we suggest several optimized schemes to reconstruct the lost and erroneous MBs of inter‐encoded and intra‐encoded frames. A hybrid method combining the Circular Scan Order Interpolation Algorithm (CSOIA) and Partitioning Motion Compensation Algorithm (PMCA) is proposed for intra‐frame EC. For inter‐corrupted MBs, a hybrid method comprising Directional Textural Motion Coherence Algorithm (DTMCA) and Directional Interpolation Error Concealment Algorithm (DIECA) is suggested. Experimental outcomes on several 3D MVV frames demonstrate that the suggested EC algorithms have more robustness to both heavily random and slice losses. They objectively and subjectively work better than the state‐of‐the‐art EC techniques. The proposed work achieves high 3D MVV quality with an improved average Peak Signal‐to‐Noise Ratio (PSNR) gain up to 2.45 to 4.55 dB compared with traditional EC algorithms at Packet Loss Rates (PLRs) of 40%.     

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%.