More specifically, the elements of the compressed sequence themselves should serve as search keys. The concept of compression is thus extended from only producing an efficient representation, to also providing a meaningful one. While vast energies have been expended in the development of video databases, relatively little of it has focused on using motion to describe object activity. This approach usually requires the video that will be classified to be divided into scenes and shots. A shot is defined as a sequences of frames filmed either from a fixed camera position, or using coherent camera motion, such as panning, rotation and zooming.
Scenes are groups of shots which exhibit some consistency in the context of the plot of the video.
Shot classification is a fairly well developed technique. Once the shot boundaries are determined, several techniques can be applied. Most methods select a single representative frame from each shot and apply some still picture analysis methods to it. Depommier et al. The idea of using multi-scale representations to facilitate searches by example has found application to the field as well.