How to Slice a Clip into Multiple Sections in After Effects

Introduction

Slicing a clip into multiple parts is a popular technique for split-screen animations, stylized transitions, and dynamic motion graphics. In this tutorial, you’ll learn how to divide a single video into multiple vertical slices using solids, track mattes, and smooth animation in After Effects.

Step 1: Import Your Footage

Go to File → Import → File and import your video into the Project panel.Step 2: Create a New Composition

Create a new composition that matches your video settings (for example, 4096 × 2160).

Step 3: Create Solid Masks for Slicing

Go to Layer → New → Solid and create three (or more) solids. Each solid should be the same size and together fully cover the composition. Example for a 4096 × 2160 video sliced into 3 vertical sections:

Solid width: 1365 px
Solid height: 2160 px

Position the solids side by side so they completely cover the composition frame.

Step 4: Duplicate the Video Layer

Based on the number of solids, place the same video above each solid:

Drag the same video from the Project panel onto the timeline three times
Each video layer should be positioned above its corresponding solid Step 5: Set Track Mattes

In the Track Matte column:

Assign each video layer to its corresponding solid
For each video layer, choose Alpha Matte

Each video layer will now be visible only inside its slice.

Step 6: Animate the Slice Movement

Animate the Position of the solids:

Move the playhead to the start of the composition

Enable the Position stopwatch for each solid

Keep the initial position unchanged

Move the playhead to the middle of the composition

Animate the solids moving apart in different directions, creating a slicing effect

Step 7: Smooth the Animation

Select all position keyframes. Apply Easy Ease and fine-tune the motion using the Graph Editor for smoother movement. Step 8: Preview the Composition

Preview the composition and adjust spacing, timing, or easing until the slice animation feels clean and dynamic.

Conclusion

By using solids as track mattes, you can easily slice a single clip into multiple sections and animate them independently. This technique is flexible, resolution-independent, and perfect for creative transitions, split-screen layouts, and modern motion design.