【作者】 牟晶晶；

【导师】 张帆；

【作者基本信息】 湖南大学 ， 控制理论与控制工程， 2006， 硕士

【摘要】 随着科学技术的不断发展,数字视频已经开始走出实验室和专业领域,进入了寻常百姓的视野中,数字电视就是这一发展的体现。做为数字电视的中间产品――数字电视接收机呈现出了巨大的市场。本文对数字电视机顶盒视频处理过程中的相关技术,主要对视频后处理过程中所采用的各种插值方法进行了分析。介绍了基于STi5518芯片的数字机顶盒方案,对该方案中所采用的视频后处理方法进行了介绍。阐述了数字视频和模拟视频原理,以及影响图像清晰度的各种因素。然后针对现行机顶盒视频后处理现状,分析了视频后处理所采用的方法,包括采样率转换、去隔行、帧率提升等。本文主要就去隔行算法进行了详细地分析和说明,并对运动补偿去隔行算法提出了新的思路。针对已经提出的线性去隔行和运动自适应去隔行算法存在的缺陷,着重在保护运动图像细节和噪声的滤除方面进行考虑,并兼顾硬件开销和运算时间,提出了在运动补偿去隔行过程中的前期运动检测单元加入自适应中值滤波保护图像细节和滤除噪声,使检测出的静止和运动像更加准确,同时采用双向块匹配运动估计,得到更加精确的运动矢量。整个算法大大减少了运算量,提高了算法的鲁棒性。通过软件仿真验证了该种算法在理论上对图像细节具有保护作用并且对图像清晰度有较大提高。阐述了对于视频处理过程中误码的解决方法,着重对于视频后处理过程的误码检测和掩盖方法进行了说明,这些方法也是现行解码芯片普遍使用的误码解决方案。并对STi5518芯片在视频处理过程中的错误检测和掩盖方法进行了分析和说明。最后针对现行的机顶盒方案,如何将图像质量进一步提高,及本文算法的硬件实现提出了展望。更多还原

【Abstract】 With the development of technology, digital video begin access common people’s view from lab and some special fields. DVB is the symbol of this development. As the DVB transitional product ---STB have very large market.This paper analyze the technology of video processing in STB, and the emphasis is putted on the interlaced algorithm of video post-processing. In this article ,the STB scheme based on STi5518 chip and the video post-processing methods be introduced. And then, expatiate the digital video and analog video elements and several factors that can affect the video definition. Aiming at the present condition of STB video post-processing, analyze the video post-processing algorithms which include sampling conversion, de-interlace and frame rate up-conversion. This article mainly analyze de-interlace algorithm, for motion-compensated de-interlace algorithm give a new method. This method aimed at avoiding the limitation of liner de-interlace and motion adaptation de-interlace algorithm, and put emphases on image detail protection and noise elimination, at the same time consider the cost of hard ware and operation spending. The first step of this method is in the motion-detection unit, we add an adaptation median filter in order to protect image details and eliminate noise, so the motion-detection result more precise. The second step is that adopting bidirectional block matching motion-estimation ,this way can get more exact motion-vector, at the same time can reduce the operation spending and improve robust. The last step is de-interlacing. The result of software emulation prove that this method can protect image details and improve video definition in theory. The fifth chapter expatiate the resolve method of false code during the video processing. The emphasis is put on the false code resolve method in video post-processing. These methods are adopted in many video processing chips include STi5518.At the end of this article, give an expectation of video post-processing in STB, and for the realization of my method give a plan.更多还原