文档介绍：摘要
多媒体通信将是新一代通信系统的典型业务和显著特征,而视频编码技术是多媒
体技术的基础和核心。随着多媒体数字业务的迅速发展,编码复杂度日趋提高,高效
快速的编码算法的研究与实现已成为视频图像传输的技术关键。
本文首先介绍了图像数据压缩方法和以MPEG系列、、AVS标准为代
表的国内外主流视频编解码标准,并基于视频压缩编码技术的理论依据,深入研究了
AV S 视频压缩标准的编码框架和实现原理,对其关键技术进行了分析与总结,并比较
了AV S ,MPEG-4的异同,在不影响图像质量的前提下,以提高编码速度为目
的,研究并实现了AV S 熵编码算法。
本文提出了一种简单的码长估计模型,这种估计模型跳过熵编码,利用在熵编码
之前的语法元素直接估计一个块的最后编码信息的码长,并将此模型应用到率失真优
化中,从而减少 RDO 中的熵编码的调用,实验表明,这种算法在基本不影响视频质
量的前提下,能有效降低率失真优化的复杂度,节约编码时间,易于硬件实现。
针对 AV S 中 2D-VLC 熵编码的特点,基于达芬奇(DM6446)DSP 的系统,对其
进行 DSP 上的优化;研究了基于 DSP 的代码级,内联函数及线性汇编的优化方法,
对 2D-VLC 熵编码中的码表,哥伦布编码及写码流算法提出了优化策略并实现之,实
验表明这些优化方法可使熵编码在 DSP 上运行的周期数减少近一半。
最后对全文进行总结,对有待继续研究的工作提出初步设想。
关键词: 视频编码; 中国音视频标准(AVS); 二维自适应变长编码; 熵编码; 率失真优
化; DSP 优化
I
Abstract
With the emergence works, along with the rapid growth of
multimedia service, the role played by munication has e increasingly
important and essential in next munication system. Video coding is the
fundamental and kernel tech in emerging multimedia/munication. With the rapid
development of digital multimedia technology, plex fast and efficient coding
algorithms have e the key technique for both video and image transmission.
The main pression methods are introduced firstly,the key technologies and
characteristics of the most famous video coding standards, like MPEG series, series
and AVS are analyzed. Based on the theory of pression technology, the coding
frame and principle of AVS has been researched , then AVS pared with and
MPEG-4; the AVS entropy coding is realized aiming at increasing the coding efficiency.
Then a simple bit-rate estimation model is proposed, which makes entropy coding
unnecessary in the rate-distortion optimizing process. This model can estimate approximate
bit rate through some syntax elements directly, therefore, reducing entropy coding cost.
Experiments show that the algorithm can reduce the plexity and save coding
time with acceptable loss of video quality. It is convenien