Audio and video are completely separate assets, and it’s time to start treating them that way in your film and video projects.
J- and L-cuts get their names from how they look on a timeline track. With an L-cut, the audio from your initial clip continues underneath the video of the next clip. For the J-cut, the audio extends under the video of the previous clip. While they are most commonly found in dialogue scenes, you can also use them to strategically position B-roll footage, smooth transitions, and fine-tune the timing of your film. Let’s take a closer look at these two versatile cuts.
For this tutorial, I am working on a documentary about hurricanes. My producer recently gave me a few clips that he wants to include in the introduction to the documentary. He’s asked for a specific sequence length of 10 seconds, as this piece is for broadcast and needs to be exact. The problem is that several of these clips don’t have any audio. We can quickly get around this issue with a few J- and L-cuts.
Performing the L-Cut
So I already have the rough cut of my sequence here. The first clip is a view of a hurricane from space, while the second and third clips are B-roll footage of a storm. The second clip is the only one that includes natural sound. Since the raw of this shot is actually 15 seconds long, I can extend just the audio out underneath the third clip. As you can see in the image, this is called an L-cut because it resembles an L shape.
Now, when I play back the last two clips, the natural sound works perfectly with both shots. The L-cut helps to avoid a jarring cut due to a change in sound. In fact, it would be difficult for the average viewer to distinguish which clip carried the natural sound originally. Even if the third clip did have natural sound, it would still benefit from an L-cut. Using the same audio helps create a better transition between the shots.
Performing the J-Cut
The first shot in this sequence also lacks audio. While the natural sound of a storm doesn’t really work for the entire shot, it’s definitely useful for transitioning from the first shot to the second. I can do this with a J-cut. To perform a J-cut, I’ll extend the audio of the second shot back a bit underneath the first clip. Then I can add a transition to slowly bring the audio in. Since this is the intro to the documentary, music and title graphics will cover this part .
To make these cuts easier in Adobe Premiere Pro, I can use a few shortcuts. First, holding the alt key will allow me to select only the audio. I can also unlink the clips by selecting my shot and going to Clip > Unlink. Once in place, I can fine-tune the edits with the Rolling Edit tool. If you want to unlink all of your clips, simply press the “Linked Selection” button in the upper left-hand corner of the timeline.
Gaining Tight Control
In addition to creating seamless transitions, this technique also gives you control over timing and pacing. Let’s say that our documentary producer came back and asked to extend our sequence from 10 to 12 seconds. It’s much easier now that I only need to adjust one audio clip instead of several. I can even swap the last two B-roll clips if I so desire.
This technique reinforces the simple and obvious fact that video and audio are separate assets, so filmmakers should treat them as such. Just because audio and video are linked doesn’t mean you have to use them that way. Slight adjustments using J- and L-cuts can drastically improve your production.
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