Kdenlive Time Remapping Guide: Precise Speed Ramps

This guide provides a step-by-step walkthrough on how to use Kdenlive’s Time Remapping tool to create smooth and precise speed ramps in your video projects. You will learn how to enable the time remapping interface, add keyframes to control speed, adjust interpolation curves for seamless transitions, and apply the final speed effects directly to your timeline clips.

How to Access the Time Remapping Tool

To begin, make sure your video clip is imported and placed onto the Kdenlive timeline.

  1. Right-click the clip on your timeline that you want to speed ramp.
  2. Select Time Remapping from the context menu.
  3. This action opens the dedicated Time Remapping panel (usually on the right or left side of your workspace), displaying a graph.

In this graph, the horizontal axis (X-axis) represents the original time of the clip, while the vertical axis (Y-axis) represents the remapped output time. A straight, diagonal line from the bottom-left to the top-right indicates that the clip is playing at normal (100%) speed.

Adding Keyframes to Control Speed

To change the speed of specific parts of your clip, you must add keyframes to the diagonal line.

  1. Move the playhead in the Time Remapping preview to the point where you want the speed change to begin.
  2. Click the Add Keyframe button (the green plus icon) or double-click directly on the diagonal line to create a keyframe.
  3. Move the playhead further down the timeline and add a second keyframe where the speed change should end.
  4. Drag the keyframes up or down to adjust the speed:
    • Steeper Line: Dragging a keyframe upward increases the slope of the line, which speeds up the playback of that section.
    • Flatter Line: Dragging a keyframe downward decreases the slope, which slows down the playback.
    • Horizontal Line: A perfectly flat, horizontal line pauses the action, creating a freeze frame.

Creating Smooth Speed Ramps

By default, Kdenlive connects keyframes with straight lines (linear interpolation), causing sudden, jarring changes in speed. To achieve a smooth speed ramp:

  1. Select the keyframe where the speed change begins.
  2. Look at the keyframe properties in the Time Remapping panel and change the interpolation type from Linear to Smooth (or Bezier).
  3. Adjust the Bezier handles that appear on the keyframe. Dragging these handles allows you to customize the acceleration and deceleration, easing the video smoothly into the fast or slow motion.

Applying and Previewing the Effect

After adjusting the curves to your satisfaction, you need to apply the changes to your timeline.

  1. Click the Apply button at the bottom of the Time Remapping panel.
  2. Kdenlive will automatically resize the clip on your timeline to accommodate the new duration resulting from your speed changes (slowing down a clip makes it longer, while speeding it up makes it shorter).
  3. Play back your timeline to preview the speed ramp. If further adjustments are needed, simply select the clip and modify the keyframes in the Time Remapping panel again.