ENF Signal Induced by Power Grid: A New Modality for Video Synchronization

Multiple videos capturing the same scene from possibly different viewing angles may be synthesized for novel immersive experience. Synchronization is an important task for such applications involving multiple pieces of audio-visual data. In this work, we exploit the electric network frequency (ENF) signal inherently embedded in the soundtrack and/or image sequence of video to temporally align video recordings. ENF is the supply frequency of power distribution networks in a power grid. Its value fluctuates slightly from its nominal value of 50 Hz or 60 Hz, and the fluctuation trends stay consistent within the same grid. Audio and video recordings that are created in areas of electric activities may capture the ENF signal due to electromagnetic interferences and other physical phenomena. We propose to synchronize video recordings by aligning the embedded ENF signals. Without major constraints on viewing angle and camera calibration as many existing methods impose, the proposed approach emerges as a new synchronization modality.