中文摘要：

目的分布式视频编码较其传统视频编码具有编码简单、误码鲁棒性高等特点，可以很好地满足如无人机航拍、无线监控等新型视频业务的需求。在分布式视频编码中，视频图像被交替分为关键帧和Wyner—Ziv帧，由于受到信道衰落和干扰等因素的影响，采用传统帧内编码方式的关键帧的误码鲁棒性远不如基于信道编码的Wyner—Ziv帧。关键帧能否正确传输和解码对于Wyner—Ziv帧能否正确解码起着决定性的作用，进而影响着整个系统的压缩效率和率失真性能。为此针对关键帧在异构网络中的鲁棒性传输问题，提出一种基于小波域的关键帧质量可分级保护传输方案。方法在编码端对关键帧同时进行传统的帧内视频编码和基于小波域的Wyner—Ziv编码，解码端将经过错误隐藏后的误码关键帧作为基本层，Wyner—Ziv编码产生的校验信息码流作为增强层。为了提高系统的分层特性以便使系统的码率适应不同的网络条件，进一步将小波分解后图像的各个不同层的低频带和高频带组合成不同的增强层，根据不同信道环境，传输不同层的Wyner—Ziv校验数据。同时对误码情况下关键帧的虚拟噪声模型进行了改进，利用第1个增强层已解码重建的频带与其对应边信息来获得第2个和第3个增强层对应频带的更加符合实际的虚拟信道模型的估计。结果针对不同的视频序列在关键帧误码率为1％～20％时，相比较于传统的帧内错误隐藏算法，所提方案可以提高视频重建图像的主观质量和整体系统的率失真性能。例如在关键帧误码率为5％时，通过传输第1个增强层，不同的视频序列峰值信噪比（PSNR）提升可达2～5dB左右；如果继续传输第2个增强层的校验信息，视频图像的PSNR也可以提升0．5～1．6dB左右；如果3个增强层的校验信息都传输的话，基本上可以达到无误码情况下?

英文摘要：

Objective Distributed video coding （DVC） has attracted the significant attention of many relevant international standardization committees and experts ever since the emergence of distributed source coding （DSC）. DSC is a new class of source coding approaches based on the Slepian-Wolf theorem and the Wyner-Ziv （WZ） theorem. Owing to its characteristic of slight encoding and high error robustness, DVC is a good way to meet the demands of the new video business, which requires low-power consumption and low complexity, such as video chat, unmanned aerial wireless monitoring, and so on. However, the bit error ratio of the wireless channel is higher than the wired channel because of the impact of the channel attenuation, muhipath interference, frequency band mutual interference, and so on. In the DVC system, video source is interleaved with key frames and WZ frames, and the side information regarded as the noise version of the current WZ frame is generated by the motion estimation and compensation algorithm of the adjacent key frames. Therefore, the key frames, regardless of their ability to correctly decode and transmit, would affect the compression efficiency and rate distortion of the whole system. However, the robustness of the key frames that use traditional intra-frame coding is far lower than that of the WZ frames, which are based on channel coding. For the robustness and transmission of key frames in the heterogeneous network, this paper presents a quality scalable protection solution for the key frames in wavelet domain DVC. Method At the encoder side, the key frames are encoded by the traditional HEVC/H. 265 （High Efficiency Video Coding） intraframe coding and Wyner-Ziv coding based wavelet domain simultaneously. The HEVC bitstreams are transmitted to the wireless channel. The information bits are directly discarded for the WZ bistreams, and the generated parity bits are stored in buffer. To make the bit rate of the system adapt to different network conditions, different layers of low-f