<title>Scene change detection and feature extraction for MPEG-4 sequences</title>

Abstract

In this paper, we present a new, computationally efficient, effective technique for detection of abrupt scene changes in MPEG-4/2 compressed video sequences. We combine the dc image-based approach of Feng, Lo, and Mehrpour. The bit allocation-based approach has the advantage of computational simplicity, since it only requires entropy decoding of the sequence. Since extraction of dc images from I- Frames/Objects is simple, the dc image-based technique of Yeo is a good alternative for comparison of I- Frames/Objects. For P-Frames/Objects, however, Yeo's algorithm requires additional computation. We find that the bit allocation-change based approach is prone to false detection in comparison to intracoded objects in MPEG-4 sequences. However, if a suspected scene/object change has been located accurately in a group of consecutive frames/objects, the bit allocation-based technique quickly and accurately locates the cut point therein. This motivates us to use dc image-based detection between successive I- Frames/Objects, to identify the subsequences with scene/object changes, and then use bit allocation-based detection to find the cut point therein. Our technique thus has only a marginally greater complexity than the completely bit allocation-based technique, but has greater accuracy. It is applicable to both MPEG-2 sequences and MPEG-4 multiple- object sequences. In the MPEG-4 multiple object case, we use a weighted sum of the change in each object of the frame, using the area of the object as the weight.