A montage cut to the beat and the same montage cut to nothing are different videos. The footage is identical. What changed is that one of them has a pulse and the viewer's body knows it.

Why cutting on the beat works

Music sets an expectation of when the next thing happens. A cut that arrives on that expectation feels inevitable; a cut that arrives between beats feels like an interruption, because it competes with a rhythm the viewer is already tracking.

This is not a matter of taste. It is why a shot held four beats too long feels slow even when it is objectively short, and why a rapid-fire sequence on the beat feels controlled while the same speed off the beat feels frantic.

An editing timeline: video clips, a zoom keyframe and an audio track below.

AVFoundation is the layer underneath - Apple's media framework, and what a Mac editor uses to assemble a timeline and encode the finished file.

Detecting the beats

Zella analyses the music track on your device and marks the onsets, so you are placing cuts against real markers rather than counting bars by ear. Open the music in Zella, run the beat detection, and the markers appear on the timeline.

Two controls shape what you get.

Sensitivity decides how many beats it finds. Turn it up on a sparse track where the drums are quiet, turn it down on a dense one where every sound is being counted.

Band decides which part of the kit it listens to, and it matters more than sensitivity:

Band What it follows Cutting feel
All beats Every onset it can find Busy - good for finding structure, rarely good for cutting
Kick (bass) The low thump Slow, weighty, one cut per bar or two
Snare / body The backbeat The classic montage pulse
Hats / cymbals The fast top end Rapid-fire, four to eight cuts a bar

Picking a band is picking a pace. A travel montage on the kick and the same footage on the hats are different edits, and it is far quicker to switch band than to move thirty cuts.

Land the cut slightly early

The detail that separates a montage that feels tight from one that feels marginally late: put the cut one or two frames before the beat, not exactly on it.

Sound registers faster than picture. A cut placed exactly on the transient reads as arriving just after it, because your ear has already processed the drum by the time your eye has processed the new frame. Nudging the cut a frame or two earlier makes the two land together.

At 30 fps, one frame is 33 milliseconds. That is enough to hear the difference and small enough that you will not see the cut as early.

Beat Sync for effects, not only cuts

The same beat markers can drive emphasis rather than cuts. Beat Sync pulses zooms and effects on the beat, tuned to the band you chose, so a shot can breathe with the music without being cut at all.

It is deliberately not applied for you. A one-tap pass that pulsed every video to its music would be a pass that made every video look the same, so Beat Sync stays a decision. The one-tap Make it Viral pass does add a music bed and matched sound effects, and Beat Sync sits alongside it as the thing you reach for when the music is the point.

Two effects that reward it: a subtle scale pulse on a held shot, and a punch-in that arrives on the downbeat of a new section.

Choosing the track first

Cut to the music, not the other way round. Picking the track after the edit means fitting a rhythm to cuts that were placed against nothing, and the result is a video that is nearly on the beat, which is worse than being obviously off it.

Practical order: pick the track, find the section with the clearest pulse, place your beat markers, then lay footage against them. Where to find music you can actually use matters here too, because a track you have to swap for licensing reasons at the end takes the whole edit with it.

When not to cut on the beat

Anything with speech. A talking-head video cut to a beat chops sentences, and the sentence is the content. Cut on the meaning and let the music sit under it, dipping with auto-ducking.

The mixed case is common and worth naming: a talking video with a montage section. Cut the talking on the words, cut the montage on the beat, and let the transition between the two modes be the moment the music comes up.

Frequently asked questions

Which band should I follow? The kick for slow, weighty montages, the snare for the standard pulse, the hats for rapid-fire sequences. All beats is useful for seeing a track's structure but usually too busy to cut against.

Should the cut be exactly on the beat? A frame or two before it. Sound registers faster than picture, so a cut placed exactly on the transient reads as slightly late.

Does the beat detection upload my music? No. The analysis runs on your device, like the rest of the audio work.

How many cuts should a montage have? As many as the band you chose implies. That is the point of picking a band first: it turns a pacing question into a setting rather than thirty separate decisions.

Can I pulse a zoom instead of cutting? Yes. Beat Sync drives zooms and effects from the same markers, tuned per band, which keeps a held shot alive without cutting it.

Why does my beat-cut video still feel off? Usually one of two things: the track was chosen after the edit, or the cuts sit exactly on the transients. Fix the order first, then nudge the cuts a frame earlier.