Compressed domain object tracking for automatic indexing of objects in MPEG home video

Object tracking is of utmost importance for automatic indexing of video content. This work presents an object tracker that operates directly on MPEG compressed data. Motion vectors and discrete cosine transform (DCT) coefficients directly available from the compressed video stream are exploited for the purpose of tracking. Tracking proceeds in two steps: motion vector based tracking in P and B frames within the groups of pictures (GOPs), and object identification in I frames. Colour, which is one of the strongest cues for tracking is used for the identification step. Such a system offers speed, simplicity and robustness against occlusion and camera motion, with good intra-shot tracking for shots in excess of 500 frames, as shown in the experimental results.