Enable Frame Blending for Slow Motion in After Effects

Slowing down footage in Adobe After Effects can lead to choppy, stuttering playback when the frame rate drops below the composition standard. Frame blending resolves this by calculating and generating intermediate frames between existing ones, resulting in smoother motion. This guide walks you through the exact steps to enable frame blending on your layer and composition, including how to choose between standard Frame Mix and advanced Pixel Motion for the best visual quality.

Step 1: Slow Down Your Footage

Before applying frame blending, adjust the speed of your clip on the timeline:

  1. Right-click the video layer in your timeline.
  2. Navigate to Time > Time Stretch (or press Ctrl+Alt+R on Windows / Cmd+Opt+R on Mac).
  3. Increase the Stretch Factor percentage to slow down the clip (for example, set it to 200% for half-speed), or enter a longer target duration.
  4. Click OK.

Step 2: Turn On Layer Frame Blending

To apply blending to the specific clip, you must activate the switch on the layer itself:

  1. Locate your layer in the timeline panel. If you do not see the switches column, click Toggle Switches / Modes at the bottom of the timeline panel or press F4.
  2. Find the Frame Blending column, represented by an icon of a film strip moving diagonally across another strip.
  3. Click the checkbox in the Frame Blending column for your target layer:
    • Click once for Frame Mix: This displays an icon with a solid arrow over a film strip. Frame Mix blends neighboring frames together like a crossfade. It renders quickly and works well for subtle speed adjustments.
    • Click twice for Pixel Motion: This changes the icon to an arrow made of dots. Pixel Motion analyzes pixel trajectory using optical flow algorithms to generate entirely new in-between frames. This produces the smoothest slow-motion results with minimal ghosting.

Step 3: Enable the Global Frame Blending Switch

Frame blending will not be visible in your preview or export until you activate the master switch for the composition:

  1. Look at the top of the timeline panel, directly above your layer stack.
  2. Click the Enable Frame Blending for all layers with the Frame Blending switch set button (the same film-strip icon).
  3. When blue or highlighted, After Effects renders the interpolated frames during RAM previews and exports.