J Cut and L Cut
Also known as: Split Edit
What Are J Cuts and L Cuts?
J cuts and L cuts are split edits, where the sound switches from one shot to the next at a different moment than the picture. In a J cut, the next shot’s sound starts first, so viewers hear a voice or a place before they see it. In an L cut, a shot’s sound carries on after the picture has changed. The names come from the editing timeline, where each shot’s picture sits above its sound and the line between two shots bends into a J or an L.
J Cut or L Cut: Which Should You Use?
Use a J cut when the next shot should be heard before it is seen, and an L cut when the last shot’s sound should carry over the new picture. A property tour app, for example, can bring an agent’s voice in under the street view before cutting to the agent, then let that voice run on over each room.
Use a J cut for
-
Replies in a conversation
The answer starts over the end of the question, so the picture cuts to someone who is already talking instead of switching on every line.
-
Openings and scene changes
Rain, traffic or a crowd comes in over the last shot or over black, and viewers know where the story is going before the new picture appears.
-
Tutorials that return to the presenter
The presenter's voice comes back over the last step of a screen recording, then the picture cuts to them mid-sentence.
Use an L cut for
-
Interviews over B-roll
The speaker keeps talking while the picture moves to the footage they describe, so the answer runs as one take.
-
Reactions
The speaker's words carry on over a shot of the listener, which shows how the words land.
-
Endings and montages
A line or a sound runs on over the next shots, so a scene lingers, or a run of images plays under one voice.
How J Cuts and L Cuts Work in CE.SDK
In CE.SDK video editing, a split edit starts by moving a clip’s sound into an audio clip of its own, which your users can then trim apart from the picture. On the Web, Separate Audio sits in the timeline’s clip menu, and the Android Video Editor starter kit shows it in its inspector bar. iOS offers the same action as an inspector bar button.
Separate the sound from its clip
Separate Audio turns every audio track in a video clip into a separate audio clip that starts where the video clip starts, and it mutes the video clip itself. On the Web it shows for clips that have sound and play at 3x speed or slower. Your app can run the same extraction through the engine API.
Drag the edge of the sound clip
For a J cut, drag the left edge of the next clip’s sound under the clip before it. For an L cut, drag the right edge of a clip’s sound under the one after it. The edge reaches into footage beyond the clip’s in or out point and stops at the first or last frame of the source, so the sound stays in step with its picture.
Shorten the other clip’s sound
Separate the neighboring clip’s sound too and trim it, so both shots only play together where you want them to. Make split edits once the picture edit is final, since a separated sound clip stays where it is when the clips around it move.
What Could Go Wrong in a J or L Cut?
The sound can fall out of step with its picture, or two shots can be heard at once for longer than you meant. A shot’s sound drifts when an edit moves it against its own picture instead of lengthening it. We built split edits in CE.SDK 1.85.1 from test clips that flash and beep at the same moments, separated the sound in the editor, and checked where each beep landed against its flash.
Sliding the sound instead of extending it
Dragging the whole sound clip 0.5 s earlier, instead of its edge, made every moment of it play about 0.5 s ahead of its picture.
Changing the picture after the split
Deleting the 4-second clip before a J cut moved the next picture 4 s earlier but left its separated sound where it was, so the sound ran 4 s behind.
Leaving the outgoing sound alone
With only the incoming sound separated, the first clip's own sound kept playing, so both shots were heard together for the 0.5 s of the J cut.
FAQs
Any edit where the sound and the picture switch shots at different moments. J cuts and L cuts are its two forms, depending on whether the sound switches before or after the picture. Editors also call a J cut an audio lead or an audio advance.
A J cut sits between two separate shots and only changes when their sounds switch over. A jump cut removes footage from the middle of a single shot, and the person on screen appears to jump forward.
No. A split edit decides when the sound changes, and a video transition decides how the picture changes, so the two can sit on the same edit. In CE.SDK, a transition blends the two clips' audio for as long as it blends their pictures, so a split edit is how the sound switches at another moment.
Keep the overlap short, or keep one sound lower than the other while both play. Apple's Final Cut Pro guide suggests trimming the outgoing clip's audio, or adjusting levels and fades so the overlap sounds natural. When music runs under a voice, our audio ducking page shows how far to lower it.
Links
Documentation and references for this concept.
Video Editor SDK
Let your users separate a clip's sound and trim it apart from the picture.
Create and Edit Audio
Extract the audio of a video into a separate block that keeps the same trim and speed.
Customize the Clip Context Menu
Show, hide or reorder Separate Audio and the other actions in the timeline clip menu.
Related Terms
Jump Cut
A cut that removes time from a single shot of a subject, so the person or object appears to skip ahead while the camera …
Video Transitions
What happens on screen where one clip ends and the next begins: a plain cut, or an effect such as a cross-fade, fade, wi…
Audio Ducking
Lowering one sound while another plays, most often background music while someone speaks, and raising it again when the …