Synchronisation is the process of establishing the exact relationship between two or more pieces of audiovisual material—knowing when one piece of footage begins, relative to another.
Synchronising images or videos in space and time can be done using visual clues, such as the shape of bomb clouds or the movement of people. Pieces of video or audio can be synchronised using their sound profiles. Witness testimony can also be ‘synchronised’ to a video or audio recording if there is an important, distinct element, such as an explosion or a gunshot, that is either captured or described in both.
Synchronisation is necessary whenever we are working with multiple pieces of evidence, not all of which have accurate metadata. Once multiple pieces of evidence are reliably synchronised by reference to their contents, the accurate metadata of one piece ‘anchors’ the others in time and space.