What Is a Prelap in Film Editing? J-Cut vs L-Cut, Explained
A prelap is when the next scene's sound starts before the picture cuts to it. What it does, how it differs from an L-cut, how to build one in Resolve or Premiere, and why we named a tool after it.
By Sami Ullah, founder of Prelap and of the video editing agency Vidify. Written from running real client revision rounds, not from a feature list.
If you have read a screenplay, you have seen the word in capitals: PRELAP. If you have cut anything longer than a social clip, you have built one without thinking about it. A prelap is one of the oldest, quietest tools in editing, and it is also the reason our feedback tool is called what it is. Here is the term, the technique and the difference between a J-cut and an L-cut.
Prelap, defined
A prelap is a transition where the audio of the next scene begins before the picture cuts to that scene. You are still looking at the end of scene A while you start hearing scene B: a line of dialogue, a car engine, a crowd, a music cue. Then the picture catches up. On a timeline the audio clip pokes out to the left of its video clip, which makes the shape of a J, so editors also call it a J-cut.
Screenwriters use PRELAP as a slug in the script to tell the editor that a sound should arrive early. Editors use it as a verb: 'prelap the dialogue by a second.' Either way the meaning is the same: sound first, picture second.
Prelap vs postlap: J-cut vs L-cut
| Term | What happens | Timeline shape | Typical use |
|---|---|---|---|
| Prelap (J-cut) | Next scene's audio starts before its picture | Audio extends left under the previous video | Pulling the viewer into the next scene; hiding a hard cut; interviews where the answer starts before we see the speaker |
| Postlap (L-cut) | Current scene's audio continues after the picture has cut away | Audio extends right under the next video | Reaction shots; letting a line land on someone else's face; ending a scene on a lingering sound |
Both techniques do the same job from opposite directions: they decouple the sound edit from the picture edit so the cut feels continuous instead of mechanical. Most conversations in film and television use a mix of the two. Watch any two-person dialogue scene and count how rarely the picture and the sound change on the same frame.
Why editors use prelaps
- Momentum: hearing the next scene early makes the audience lean forward instead of resetting at every cut.
- Smoothness: a hard cut with a simultaneous audio change draws attention to itself; a prelap hides the seam.
- Emphasis: starting a line before we see the speaker gives the words a beat of their own.
- Pace: prelapping lets you trim the tail of a scene without the ending feeling abrupt, because the sound has already moved on.
How to build a prelap in your NLE
The mechanics are the same in DaVinci Resolve, Premiere Pro and Final Cut Pro: separate the audio from the video, then slide the audio edit point earlier than the picture edit point.
- 1Place scene A and scene B back to back on the timeline.
- 2Unlink (or alt/option-select) the audio of scene B so you can move it independently of its video.
- 3Drag the start of scene B's audio to the left, under the end of scene A's video, by the amount you want: half a second for a subtle lead, two to three seconds for a deliberate pull.
- 4Trim or fade the end of scene A's audio so the two do not fight, and check the sync of scene B's picture is untouched.
- 5Scrub across the cut. If the sound arrives, then the picture, you have a prelap.
In Resolve, the trim tool with audio and video unlinked does this in one drag. In Premiere, hold Alt (Option on Mac) to select only the audio, then roll the edit. In Final Cut, expand audio/video and drag the audio edge. Most editors keep a keyboard shortcut for 'toggle linked selection' because they do this dozens of times a day.
Why our feedback tool is called Prelap
A prelap is sound arriving before the cut. Prelap, the product, is notes arriving before the cut: it takes the voice notes a client records on the review link, plus any texts and emails you paste in, and turns them into a timestamped revision checklist before you open the timeline, then exports each note as a marker in your NLE. You hear what the client wants first, and then you cut. If you were searching for the film term, the definition above is the whole answer. If you were searching for the tool, it is free to start.
Frequently asked questions
What does prelap mean in film?+
Prelap means the sound from an upcoming scene is heard before the image of that scene appears. The audio 'laps' over the cut ahead of the picture. In script and editing shorthand it is written as PRELAP, and on a timeline it looks like the letter J, which is why editors also call it a J-cut.
What is the difference between a prelap and an L-cut?+
In a prelap (J-cut) the next scene's audio starts early, before its picture. In an L-cut (postlap) the current scene's audio continues after the picture has already cut to the next scene. J leads with sound; L trails with sound.
Is Prelap the tool related to the editing term?+
Yes, by name only. Prelap the product is an AI video feedback tool: it turns the voice notes, texts and emails clients send into a timestamped revision checklist. The name is a nod to the technique: you get the notes before you cut.