HEVC码率控制算法研究

发布时间：2018-02-21 18:10

本文关键词： HEVC 码率控制 R-l模型 gpp　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：3G技术和Internet技术的高速发展,使得当前主流的H.264/AVC编码标准不能满足人们对于高分辨率视频的要求,JCT-VC研究的高效率视频编码HEVC逐渐兴起。在实际的应用中,由于带宽资源的稀缺和有限性,如何在限定带宽下保证编码质量成为了视频编码中的一个重要问题,这就是码率控制技术所研究的内容。而对于不同的应用,对码率控制的要求有着不同的侧重点,生活影音娱乐中,对视频质量的要求比较高,而在视频会议等实时视频传输应用中,就要求传输系统延迟低,实时视频传输应用的快速发展使得针对低时延的码率控制成为一个研究的热点。本文对HEVC编码标准的技术特点和码率控制的原理进行理论分析和总结,针对HEVC标准测试模型(HM)中采用的JCTVC-K0103提案中的码率控制算法在低延时应用的不足,对算法的码率分配方案进行了改进。在帧级,在分析虚拟缓冲区状态和帧编码比特的关系基础上,提出了基于虚拟缓存区状态的比特分配方案。在基本编码树单元CTU(Coded Tree Unit)级,在R??(Rate-Lambda)模型的基础上,用数值解法得到了一种新的权重,然后根据该权重和帧级缓冲区的状态对未编码的CTU进行了比特分配。实验结果显示,在考虑缓存区状态进行比特分配后,码率控制的更加精确,能够解决缓存区溢出和下溢的问题,从而达到低延时的目的。同时,R??模型对于I帧控制的不准确性,使得码率控制算法的性能在遇到场景切换时会受到很大的影响,由此引入单位像素梯度(gpp,gradient per pixel)对R??模型进行了优化。实验结果表明,将优化后R??模型用于I帧码率控制后,I帧比特分配更加精确,能够获得更平稳的帧比特以及更加连续和稳定的视频质量。
[Abstract]:With the rapid development of 3G technology and Internet technology, the current mainstream H.264% AVC coding standard can not meet the requirements of high resolution video. The high efficiency video coding HEVC studied by JCT-VC is emerging gradually. Due to the scarcity and limitation of bandwidth resources, how to guarantee the coding quality under limited bandwidth has become an important problem in video coding, which is the research content of bit-rate control technology. The requirements of rate control have different emphases. In live video entertainment, the demand for video quality is relatively high, but in real-time video transmission applications such as video conferencing, the transmission system delay is low. With the rapid development of real-time video transmission applications, low delay rate control has become a hot topic. This paper makes a theoretical analysis and summary of the technical characteristics of HEVC coding standard and the principle of bit rate control. In view of the shortage of the rate control algorithm in the JCTVC-K0103 proposal used in the HEVC standard test model, the rate allocation scheme of the algorithm is improved at the frame level. Based on the analysis of the relationship between the virtual buffer state and the frame coding bits, a bit allocation scheme based on the virtual buffer state is proposed. ? Based on the Rate-Lambda) model, a new weight is obtained by numerical method, and then the uncoded CTU is allocated according to the weight and the state of the frame level buffer. The experimental results show that after the buffer state is considered, the bit allocation is carried out. The rate control is more accurate, which can solve the problem of buffer overflow and underflow, so as to achieve the goal of low latency. ? Because of the inaccuracy of the model for I frame control, the performance of the rate control algorithm will be greatly affected when the scene is switched, so the unit pixel gradient gradient per pixel is introduced. ? The model is optimized. The experimental results show that the optimized R? ? After the model is used for I frame rate control, the allocation of I frame bits is more accurate, and more stable frame bits and more continuous and stable video quality can be obtained.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN919.81

【共引文献】