Studying the impact of sequence clustering on near-duplicate video retrieval: an experimental comparison

In this paper, we propose studying the impact of clustering on near-duplicate video (NDV) retrieval. The aim is to reduce the search space at retrieval time through a pre-processing clustering step performed on the dataset off-line and retrieving NDVs based on the formed clusters. Our contribution is a novel clustering framework inspired by a bioinformatics technique, namely DNA multiple sequence alignment (MSA). A series of video keyframes in chronological order is represented as an alphabetical genome, analogous to a DNA sequence and MSA is employed to automatically partition the NDVs in a video collection into clusters. After discussing the advantages and shortcomings of the main state-of-the-art clustering approaches for video clustering in the theoretical part of the paper, we empirically evaluate the performance of the proposed MSA-based framework against five clustering algorithms representative of these mainstream approaches: Birch, Cure, Dbscan, Expectation-Maximization and Proclus. Also, we show that our clustering-based approach, while being significantly faster than non-clustering-based n-gram and edit distance NDV retrieval techniques, yields better mean average precision retrieval accuracy.