How to fit music to your video's length on the beat

Music almost never comes at the length you need. The track is three minutes and your video is two minutes ten. Fading out early sounds lazy, and chopping a chunk out by ear usually leaves a stumble where the beat skips. Video by Zaweba has a tool that does what a music editor would: it cuts or repeats whole bars in the middle of the track, on the beat, so the result sounds like the piece was written to that length.

Tempo, phase and downbeat

First it analyses the music to find the tempo, the phase (where each beat falls) and the downbeat, the first beat of each bar. With that map of the song, it looks for places in the middle where the music matches best, two points that sound alike, and either takes out the bars between them or repeats a section to make it longer. The joins are crossfaded on bar lines, so the rhythm carries straight through.

Working in the middle matters. The opening and ending of a piece of music are what people recognise and remember, and a clean ending is far better than a fade. By leaving the start and finish alone and adjusting the middle, the re-edit keeps the track's shape.

Three ways to use it

Edit > Re-edit music to a length takes a music clip and a target length. Set the length you need and the app does the rest.

The music re-edit tool, on Shift+R, works on the timeline. It's handy when you'd rather drag a music clip to the length you want and have it re-edited to fit.

Fit the music bed to the episode is the third. It's made for series work and the Episode Builder, where the episode's length is decided by the shots and the voiceover. One command stretches or shrinks the music bed to cover the whole episode.

Getting the best results

Steady music works best. Tracks with a clear, constant beat, such as pop, dance, many library tracks and most background beds, give the analysis an easy job. Music with tempo changes, free rubato passages or no clear pulse is harder, and the result may need a check by ear.

Ask for a sensible change. Taking thirty seconds out of a three-minute track is easy. Asking for ten seconds from a five-minute piece leaves very little to work with, and the joins may land in obvious places.

Listen to every join. The crossfades fall on bar lines, so they're usually invisible, but if a melody or a lyric is cut midway it can still be noticed. If one join bothers you, try a slightly different target length and the tool may pick a different spot.

Fitting it into an edit

Lock the picture before you re-edit the music, or as close to locked as you can. If the edit keeps changing, you'll be re-fitting the music each time.

Then line up the big moments. A music change on a scene change feels deliberate. After the re-edit, nudge the clip if a strong downbeat lands just off a cut you care about.

Finally, let the automatic ducking and your mix sit the music under the dialogue. In Video by Zaweba, a re-edited bed that ends cleanly on its final chord gives a film a finish that a fade-out never quite manages.