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题名:
易错信道中容错视频编码技术研究
作者: 徐进
答辩日期: 2007-06-05
授予单位: 中国科学院软件研究所
授予地点: 软件研究所
学位: 博士
关键词: 容错视频编码 ; 冗余片 ; 帧内刷新 ; 多描述视频编码 ; 人眼视觉系统 ; H.264/AVC
其他题名: Research of error-resilient video coding techniques over error-prone channels
摘要: 因为目前常用的视频编码国际标准如MPEG-x以及H.26x都采用了基于块的混合编码技术,使得生成的码流对信道误码非常敏感,因而,为了在Internet和无线网络等易错信道中进行高效的视频通信,必须采用有效的差错控制技术提高编码视频流的容错性能。本文概述了目前视频通信中常用的差错控制技术,简要介绍了最新的视频编码标准H.264在压缩编码和抗误码编码方面的技术亮点,重点研究了易错信道中的容错视频编码技术,主要取得了以下几个方面的研究成果: 第一、针对H.264创新的抗误码技术-冗余片技术,提出了一种内容自适应的冗余片编码算法。它能在实际编码前通过分析视频图像的运动信息以及纹理特征确定视频图像中的视觉敏感区域,并利用动态的灵活宏块排列技术仅对属于视觉敏感区域的片应用冗余片技术进行保护。实验结果表明,该算法能明显地提高重建视频的主客观质量。 第二、提出了一种结合人眼视觉特性的率失真优化帧内刷新算法。该算法在计算端到端的全局失真时引入了视觉敏感因子,使得位于不同区域的宏块能得到与人眼视觉特性相符的全局失真,从而保证具有较大视觉失真期望值的宏块能得到更及时的帧内刷新。实验结果表明,本文提出的新型帧内宏块刷新算法能取得比传统的率失真优化帧内刷新算法更好的主观质量。 第三、提出了一种基于自适应帧内刷新的联合抗误码算法。该算法可以在对当前帧进行实际编码前得到该帧在当前信道状况下最优帧内刷新率,并且能根据图像中每个宏块的信道失真估计值确定当前帧需要进行帧内编码的宏块,同时利用动态的灵活宏块排列技术对每帧中的帧内宏块进行着重保护。实验结果表明,该联合抗误码算法能明显提高重建视频的质量。 第四、提出了一种基于感兴趣区的多描述视频编码算法。它利用基于感兴趣区的非线性变换技术,使得每个描述包含了更多有关感兴趣区的信息,从而保证感兴趣区能更好地进行解码重建。实验结果表明,该多描述视频编码算法能明显提高重建视频中感兴趣区的质量。
英文摘要: Due to the block-based hybrid coding framework adopted by most video coding standards such as H.26x and MPEG-x, the coded video data becomes extremely vulnerable to transmission errors. Therefore, in order to realize effective video communication over such error-prone channels as Internet and wireless network, various error control techniques should be adopted to enhance the error-resilience of the coded video data. In this dissertation, the common error control techniques used in a typical video communication system is firstly reviewed, which is followed by a brief description of the novel coding techniques and error-resilient tools adopted by H.264, a state-of-the-art video coding standard. Then, special emphasis is focused on research of error-resilient video coding under error-prone environment. The main contribution and innovation points are as follows: Firstly, a content-adaptive redundant slices coding algorithm is proposed. By analyzing both motion and texture information of the original video sequence, the proposed algorithm can determine the visually sensitive regions of a video frame before it is encoded and protect the slices belonging to the visually sensitive regions with redundant slices by adopting a dynamic Flexible Macroblock Ordering (FMO) mapping technique. The experimental results show that our proposed algorithm can remarkably improve both subjective and objective quality of the reconstructed H.264 video in the packet-lossy environments. Secondly, a Rate-Distortion (R-D) optimized intra refreshing algorithm using human visual system (HVS) characteristic is proposed. Based on a simple yet effective method to measure the visual sensitivity of macroblock, the proposed algorithm can adjust its corresponding estimated overall distortion to make it accord with human visual system so that the macroblocks having bigger perceptual distortion can be intra-refreshed more timely. The simulation results show that, comparing with the traditional RD-optimized intra refreshing algorithm, the proposed algorithm can guarantee a better subjective quality of the reconstructed video at the decoder. Thirdly, a joint adaptive intra refreshment and unequally error protection algorithm is proposed. The proposed algorithm can achieve both the global optimization in determining the intra refreshing ratio and the local accuracy in selecting the proper macroblocks to be intra-coded before the current frame is actually encoded. Meanwhile, the intra macroblocks in a frame is better protected by taking advantage of dynamic Flexible Macroblock Ordering mapping technique.The experimental results show that our joint intra refreshment and unequally error protection algorithm can remarkably improve the reconstructed video quality in the packet lossy network. Fourthly, a Region of Interest (ROI) based multiple description video coding technique is proposed. Since the proposed multiple description coding (MDC) takes advantage of ROI-based nonlinear transform to make each description contain more information about ROI areas, this increased redundancy make it easy to reconstructed ROI under error-prone environment. The experimental results show that the proposed MDC can remarkably improve the reconstructed video quality for ROI in the packet lossy network.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.iscas.ac.cn/handle/311060/7408
Appears in Collections:中科院软件所

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Recommended Citation:
徐进. 易错信道中容错视频编码技术研究[D]. 软件研究所. 中国科学院软件研究所. 2007-06-05.
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