【作者】 刘琰；

【导师】 张志禹；

【作者基本信息】 西安理工大学 ， 通信与信息系统， 2007， 硕士

【摘要】 20世纪90年代以来，JPEG，H.263，MPEG-1，MPEG-2等图像多媒体国际标准相继出台，它们成功地应用于多种实用场合。但是，随着时代的发展、Internet的普及，以及对视频传输需求不断提高，现有的这些视频压缩标准明显存在着一些缺陷和局限性。H.264是目前由ITU-T的视频编码专家组(VCEG)及ISO／IEC的移动图像专家组(MPEG)大力发展研究的适应于低码率传输的新一代视频压缩标准。作为视频编解码领域的最新标准，H.264具有压缩率高、差错恢复能力强、适用范围广等优点。为达到理想的数据压缩率，H.264编码器采用了很多新的编码算法，这些算法极大地增加了编码器的计算复杂性，使其目前在PC环境下的实时应用受到很多限制。要实现H.264的实时编解码，必须对其进行大量的优化工作，但这种优化工作不应该以较大的性能牺牲为代价。本文首先介绍了视频编解码技术的国内外研究、发展现状以及H.264／AVC标准；在分析H.264／AVC编码器软件的不足和问题的基础上，结合模型自身特点，从帧内预测与帧间预测、运动估计与运动补偿以及整数变换与量化这三个不同的方面入手对H.264／AVC编码器软件进行了优化。在优化过程中改进了模式选择算法。以JM10.1软件模型为基础，进行了仿真试验，并对比了优化前后的图像视觉质量、编码时间和PSNR值变化。实验证明，在采用改进的选择算法和变换与量化过程后，在视频图像信噪比基本上不变的情况下，运算复杂度大大降低，提高了视频压缩编码效率。更多还原

【Abstract】 Entering 21 Century, the adoption of digital video has been fuelled by the development of many video coding standards in many applications. There are many video protocols such as JPEG, H.263, MPEG-1 and MPEG-2 which are targeted in different application areas. However the requirements for video transmission are increasing with the prevalence of Internet, so the video protocols have some limitation and localization nowadays. The H.264 is researched to be seasoned with low bitrate by VCEG and MPEG. As the latest standard in video codec field, H.264 has such advantage as high compression-rate, strong error resilience capacity, highly adaptability and so on. In order to gain good coding result, H.264 adopts so many new algorithms that the amount of calculation increase drastically. As a result, its applications in PC environment are restricted. In order to realize H.264 real-time codec, many optimization works have to be done. But these optimization gains should not at the cost of obviously coding performance drop.Firstly, introduced the researches about video coding Home and abroad and H.264/AVC standard. Based on the disadvantages and problems of coding soft ware, combining the individual traits of model, we optimized the coder in three aspects. The three aspects are forecast intra frame, forecast inter frames, integral transfer and quantity. The mode selection algorithm is improved. The process of integral transfer and quantity is optimized in structure. The experiment took the JM10.1 software model as the main source, carried on the simulated test, and made a contrast with the image vision quality, coding time and change of PSNR before optimizing and after it.The experiment proved that after the process of adopting improved selection algorithm, searching algorithm, integral transfer and quantity, the complication of calculation is decreased greatly. This method advanced the coding efficiency of video compressing. Finally, this paper is presented summarizer and future prospects the H.264/AVC algorithm.更多还原