Beat detection
Also known as: beat tracking, tempo detection
Finding the regular pulse in a music track and marking its position in time, which is what lets cuts be placed on the beat.
Updated
What it means
Beat detection analyses an audio file and marks the time positions of its pulse. The output is a list of timestamps rather than a single number, which is the part that makes it useful for editing.
Knowing the tempo alone is not enough. A cut has to land on a particular beat at a particular moment, so the positions matter more than the rate, and that distinguishes it from reading BPM (tempo).
On a steady electronic track it is close to solved. On live drums, a track that changes tempo or anything with a long intro, confidence drops and the grid starts to drift.
How it works in practice
The grid produced becomes the set of legal cut points for the whole edit. Shots are then trimmed to fit between beats rather than cut to their natural length, which is what Beat sync means in practice.
Downbeats carry more weight than ordinary beats. Landing the strongest moment on the first beat of a bar reads as intentional, while landing it on the third barely registers.
Checking the grid against the Waveform at the start and the end of a track catches drift early, because an error of a tenth of a second is clearly audible against picture.
What to watch out for
Detectors frequently lock onto half or double the real tempo. The grid is then perfectly regular and wrong, producing an edit that cuts twice as often as the music suggests.
Swapping the track after the edit is built invalidates every mark. A second song at a different tempo means the whole sequence has to be rebuilt, which is why the music is chosen first.
A drifting grid is worse than no grid. Cuts that start on the beat and gradually slide off sound like a mistake, while cuts placed by Pacing alone at least sound deliberate.
How RawClip handles it
The music is analysed for its pulse before any cutting happens, and the edit points are placed on that grid with the strongest moments on the heaviest beats. That is why a finished highlight feels timed to the track rather than merely accompanied by it.