视频摘要是视频内容的一种压缩表示方式。为了能够更好地浏览视频，提出了一种根据浏览或检索的粒度不同来建立两种层次视频摘要(镜头级和场景级)的思想，并给出了一种视频摘要生成方法：首先用一种根据内容变化自动提取镜头内关键帧的方法来实现关键帧的提取；继而用一种改进的时间自适应算法通过镜头的组合来得到场景；最后在场景级用最小生成树方法提取代表帧。由于关键帧和代表帧分别代表了它们所在镜头和场景的主要内容，因此它们的序列就构成了视频总结。一些电影视频片段检验的实验结果表明，这种生成方法能够较好地提供粗细两种粒度的视频内容总结。

ion is a short summary of the content of a longer video document, which helps to enable a quick browsing of a large collection of video data and to achieve efficient content access and representation. In this paper, we propose a novel approach of generating video abstraction at two levels, namely, the shot level and the scene level. The hierarchical video abstraction can facilitate video browsing and retrieval at different granularities. Firstly, the video stream is segmented into shots. A new key frame extraction algorithm, which does not rely on threshold, is put up to extract key frames from shots based on the content variation. An updated time-adaptive algorithm is used to group the shots into scene. Based on the defined shot similarity formula, the video scene structure is constructed after shot clustering and adjustment. Representative frames are extracted from the key frames of each scene using the method of generating Minimum Spanning Tree. Key frames and representative frames can represent the content of shot and scene, respectively. The sequence of key frames and representative frames is the two-level video abstraction. Experiments based on real-world movies show that the method above can provide users with better video summary at different levels.