A unified approach to detection of shot boundaries and subshots in compressed video

Abstract

This paper describes a method to partition a video sequence into shots and subshots. By subshots, we mean one or a combination of the three camera motions of pan, tilt and zoom. The proposed technique detects both hard cuts and gradual transitions in MPEG compressed video using a single technique. We also present a motion estimation algorithm to compute the dominant motion represented by an affine model. The motion information is used to refine the location of dissolves as well as to subdivide the shot into subshots, thus providing a characterization of camera motion. We consider the dissimilarity between the I-, P- and B-frames with respect to the type of macroblocks used for encoding. Unlike previous algorithms reported, our method requires minimal decompression of the video sequence and uses very loose thresholds. The algorithm is evaluated on several types of video sequences to demonstrate its effectiveness.