中文摘要：

基于软件视频会议系统是未来远程会议系统的发展趋势，而视频会议未来发展的主要关键技术之一是视频的编解码技术。针对视频会议中高带宽下显示帧访问引起视频解码器性能下降的问题，提出了一种基于软件视频会议显示帧的简单和有效的无损压缩算法。该算法基于字典编码、霍夫曼编码，提出了两种创新的编码方法，通过计算获得相邻每对像素差的分布情况和表征每对像素的空间位置LPM值，显著提高了视频显示帧的压缩比例。在定量分析视频显示帧特性的基础上，提出了一种两组分类方法。该方法将显示帧的所有像素分为三组，通过头码压缩方式减少码字的位数，以提高压缩效率。实验结果表明，相对于已有压缩算法，提出的无损压缩算法的压缩率提高了百分之二十。

英文摘要：

Software-based video conferencing system is future trend of conference system development and the coding and decoding tech- nology is one of the key technologies in the future development. In software video conferencing, performance of video decoder is usually reduced due to the high bandwidth required. Therefore a simple and efficient lossless compression algorithm based on software video con- ference display is proposed. It puts forward two kinds of innovation coding methods based on dictionary coding and Huffman coding. Through calculating the distribution of each pair of adjacent pixels difference and space LPM values of every pixels ,the compression ratio of the video display frame is increased significantly. On the basis of quantitative analysis on characteristics of video display frames, a two level classification method is presented,by which all of the pixels are divided into three groups and the code digit size is decreased to pro- mote the compression efficiency. Experimental results show that the compression ratio of the proposed algorithm is enhanced by twenty percent compared with previous algorithm.