Video feature selection using fast-converging sort-merge tree

High time complexity is a bottle-neck in video segmentation, classification, analysis, and retrieval. In This work we use a heuristic method called fast-converging sort-merge tree (FSMT) to construct automatically a hierarchy of small subsets of features that are progressively more useful for video data exploration. The method combines the virtues of a wrapper model approach for high accuracy, with those of a filter method approach for deriving the appropriate features quickly. FSMT speeds up a more fundamental method, the basic sort-merge tree (BSMT) approach, while retaining its performance. We demonstrate FSMT´s high accuracy: it has a 0.001 error rate in a frame classification task on 75 minutes of instructional video, and a 0.98 precision and 0.89 recall in a segment retrieval task on 30 minutes of sports video. Additionally, FSMT is more than 80% faster than its predecessor, BSMT.