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MPEG-4视频编码、传输过程中的码率控制
其他题名Rate-Control for MPEG-4 Video Coding and Transmission
关灵艳
学位类型工学硕士
导师李泽飞
2003-06-01
学位授予单位中国科学院研究生院
学位授予地点中国科学院自动化研究所
学位专业控制理论与控制工程
关键词Mpeg-4 视频编码 码率控制 Mpeg-4 Video Coding Rate Control
摘要随着科学技术的发展,人类社会逐渐进入了信息时代。信息的数字化带来了数据量的爆炸性增长,尤其是数字化后的视频和音频信息的数据量极大,这使信息的存储和传输变得极为困难,成为阻碍人类有效获取和使用信息的瓶颈,因此,必须对视频和音频信息进行压缩。本文全面回顾了多媒体压缩编码技术 的发展,详细介绍了常用的多媒体压缩编码方法和常用的多媒体压缩编码标准。 在回顾已有的多媒体压缩编码方法以及标准的基础上,本论文重点研究了 MPEG-4视频编码码率控制算法。针对MPEG-4标准测试模型的码率控制算法 (VM-18)中所固有的跳帧问题,分析了导致跳帧的主要原因并给出了减少跳帧的 方法。改进的码率控制算法明显减少了帧跳跃的数量,提高了峰值信噪比 (PSNR)。 本论文还针对MPEG-4视频在Internet网络上的传输,设计了一种端到端的 MPEG-4视频实时传输的传输结构。我们的传输系统包括三个部分:采用端到端 的反馈控制算法对带宽进行估计;采用基于对象的适应性码率控制算法对码率 进行分配;采用有效的打包算法在同步层对视频数据进行打包。其中码率控制 算法包括两个阶段:帧一级的码率控制和基于对象的码率控制。该算法先根据 前后帧的编码复杂度进行目标码率预测,然后根据视频对象的编码复杂度在视 频对象间分配码率,最后通过码率-失真模型求出最优的量化步长。这样求得 的量化步长从全局来讲是次优的,但是大大减小了优化问题的计算量,是切实 可行的。本算法通过将码率控制划分为两个相互独立的阶段简单而有效地解决 了MPEG-4视频实时传输的优化问题,这对于网络实时视频应用具有重要的意 义。
其他摘要Along with the development of science and technology, we have entered an information era in which the amount of digital data increases dramatically. Especially, the amount of digital video and audio is very large, which makes it extremely difficult to store and transport the information. It has become a big obstacle for us to access and use the information effectively. To tackle this problem, information compression is necessary. This thesis reviews the development of multimedia compressing technology comprehensively and introduces some commonly used multimedia compressing algorithms and some existing standards in detail. Based on the introduction of the multimedia compressing algorithms and standards, the thesis is mainly devoted to the study of the rate control algorithm for MPEG-4 video coding. Aiming to tackle the inherent frame-skipping problem of the current MPEG-4 rate control algorithm (VM-18), the main causes of frame skipping are analyzed and method for reducing frame skipping is proposed. Results show that the modified rate control algorithm reduces the frame skipping and increases the peak signal to noise ratio (PSNR) significantly. Besides we also devise a peer-to-peer real time transmission structure suitable for MPEG-4 video transporting over the Internet. The transmission system includes three stages: The available network bandwidth is predicted by using peer-to-peer feedback control algorithm; The bit is allocated using the object-based adaptive rate control algorithm; The video data is packaged into packets in the synchronization layer using efficient packetization algorithm. The rate control algorithm comprises two stages: the frame level rate control algorithm and the object level rate control algorithm. In the rate control algorithm, the target bit is first predicted according to the coding complexity of the frames. Then the bits are allocated among the video objects based on their coding complexities. Finally, the optimal quantization step is determined using the rate-distortion model. The quantization step derived in this way is sub-optimal in view of the overall situation. However it reduces the computation complexity greatly. Therefore it is a feasible and effective way in practice. The algorithm divides the rate control into two independent stages and thereby the optimization problem of the MEPG-4 real time video transmission is resolved simply, which is of great importance for the real time video transmission over the Internet.
馆藏号XWLW677
其他标识符677
语种中文
文献类型学位论文
条目标识符http://ir.ia.ac.cn/handle/173211/6836
专题毕业生_硕士学位论文
推荐引用方式
GB/T 7714
关灵艳. MPEG-4视频编码、传输过程中的码率控制[D]. 中国科学院自动化研究所. 中国科学院研究生院,2003.
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