How to Use Time Stretch in Adobe After Effects

This article explains the concept of time stretching in video editing and provides a step-by-step guide on how to apply it within Adobe After Effects. You will learn what time stretching does to your footage, how it differs from other retiming methods, the exact steps to adjust a layer's duration using the Time Stretch dialog, and how to maintain visual quality using frame blending techniques.

What Is Time Stretching?

Time stretching is the process of altering the playback speed and overall duration of a layer uniformly. When you stretch a layer, you change its speed across the entire duration rather than dynamically ramping it up or down.

Decreasing the duration (a stretch factor below 100%) speeds up the playback, causing the clip to play faster. Increasing the duration (a stretch factor above 100%) slows down the playback, extending the time it takes for the layer to complete. Unlike Time Remapping—which allows for variable speeds and keyframing—time stretching applies a constant, linear speed change from the layer's start to its end.

How to Apply Time Stretch Using the Menu

  1. Select the Layer: In your After Effects Timeline panel, click on the video, graphic, or pre-composition layer you want to retime.
  2. Open the Dialog: Go to the top menu bar, navigate to Layer > Time > Time Stretch. Alternatively, right-click the layer in the timeline, hover over Time, and select Time Stretch.
  3. Configure the Settings:
    • Stretch Factor: Enter a percentage. Values lower than 100% speed up the clip, while values higher than 100% create slow motion. For example, 50% doubles the speed, and 200% cuts the speed in half.
    • New Duration: Alternatively, enter a specific timecode or frame count to force the layer to match an exact length. The Stretch Factor will update automatically.
    • Hold In Place: Choose which point of the layer remains fixed while the layer expands or contracts:
      • Layer In-point: Anchors the beginning of the layer; the end extends or contracts.
      • Current Frame: Anchors the frame where the Current Time Indicator (CTI) is positioned.
      • Layer Out-point: Anchors the end of the layer; the beginning extends or contracts.
  4. Confirm: Click OK to apply the changes.

How to Apply Time Stretch Using Timeline Columns

  1. Open the timeline column options by clicking the Toggle switches / modes button at the bottom of the Timeline panel, or click the Expand or Collapse the In/Out/Duration/Stretch panes icon in the bottom-left corner.
  2. Locate the Stretch column.
  3. Click on the percentage value for your selected layer and enter your desired stretch percentage.

Maintaining Quality with Frame Blending

Slowing down footage via time stretching can result in choppy playback if the original frame rate is lower than the composition frame rate. To smooth out extended frames:

  1. Select the stretched layer.
  2. Click the Frame Blending switch for the layer in the Timeline panel to cycle through the options:
    • Frame Mix: Blends adjacent frames together to soften motion stutter.
    • Pixel Motion: Uses motion vectors to synthesize entirely new intermediate frames for smoother slow motion.
  3. Ensure the master Enable Frame Blending button is active at the top of the Timeline panel to preview the result.