Efficient motion-vector-based video search using query by clip

A simple and efficient motion-vector-based search engine supporting query by clip is presented for indexing and retrieving of videos. We propose a technique to filter and reconstruct noisy motion vectors to improve the fidelity of the motion activity. In addition to the motion features of intensity and direction, a new motion descriptor, named representative spectrum, extracted by a vector quantization expressing the spatial-temporal distribution of motion activity, is introduced for video indexing. A dynamic programming scheme is also utilized to measure the similarity of two videos based on the concept of common subsequence. Furthermore, a 2-step search of similar videos is employed to reduce the computational complexity. The experimental results indicate that the proposed search engine performs well and the obtained recall and precision values are also high enough.