Learn Time Remapping & Speed Ramps in After Effects

After Effects 08/03/2021 4 min read

There are many reasons you might want to change the Speed of your clips in an After Effects project; perhaps the clip needs to fit a specific length, or you want to create a slow-motion effect. Whatever your reasons for changing the Speed, knowing the variety of ways you can make an After Effects Time Remapping effect is a crucial skill for any Editor.

Part 1: What is Time Remapping in After Effects?

As we’ve already mentioned, there are several ways to change your clips’ Speed, each allowing you to create different effects. 

Freeze Frame

A Freeze Frame is probably the most commonly understood form of time manipulation, where a still image is created from a frame of your clip. Freeze Frames have various uses, and we’ve written a handy article for you to find out everything you need to know about this type of effect.

Time Stretch

Time Stretch is an excellent tool for changing a clip to a specific length or Speed, and can be done using figures and percentages rather than visually. The Time Stretch settings can be super helpful if, for example, you need to change a clip to a specific length to fit a template project.

Time Reverse Layer 

The self-explanatory titled Time Reverse Layer effect will play your clip backward. This can be an individual clip for stylistic purposes or a part of a clip to create a rewind style effect, ideal for sports content and comedy videos.

Time Remapping

Time Remapping allows you to play with the time across your clip, slowing it down and speeding it up as desired throughout, rather than having one consistent time effect. You can use time remapping to create speed ramps, where throughout your clip, the video speeds up or slows down.

One of the critical things to remember with any time effects is that overextending the footage can cause a quality loss in your clip. When you slow down a clip, you are stretching out the Frames; if you want to ensure that your Time Remapping effects are smooth, choose to shoot at a high frame rate like 50, 60, 120 FPS.

Part 2: Time Remapping in After Effects

The Time Remapping Effect can look a little confusing at first, and the best way to learn how to use it is to jump in a play around with the settings. When you add the Time Remapping Effect, a Keyframe will be added to the first and last Frame. These Keyframes indicate the clip’s actual length; move them closer together to speed up or further apart to slow down.

Step 1: Basic Speed

Firstly, let’s look at the basic Speed Keyframes;

  1. Select your layer, right-click and select Time > Enable Time Remapping or Control/Command Alt+T.
  2. Firstly, move your Keyframes closer together and play the clip back; you will notice it has sped up.
  3. Control/Command Z to undo and try again moving the Keyframes further apart. You will see that the clip slows down, but you will also notice that the clip cuts out before the end of the action. To counteract this, drag the end of your clip out to meet the Keyframe.

Step 2: Adding more Keyframes

If you add more Keyframes to your clip, you can play around with the Speed at various video stages. Remember, if you are slowing down the clip at any point, you will be increasing the Speed of other areas unless you extend your clip to counteract. 

  1. Add in some Keyframes around the points you want to speed up or slow down, and move them along the Timeline.
  2. If you want to create a Freeze Frame on a specific Frame of your clip, generate a Keyframe in the image, Copy it, and paste it further down the Timeline.
  3. If you want to Reverse a section of your Clip, swap the position of two Keyframes.
  4. To create a more subtle start and finish to your Time Keyframes, highlight them in the Timeline > Right Click > Keyframe Assistant > Easy Ease.

Part 3: Speed Ramps & Freeze Frames in After Effects

You can use Time Remapping Effects to create Speed Ramps and Freeze Frames where the clips slow and speed up according to your shot’s action. Since each Speed Ramp effect will depend on your clip, we’re going to show you how to use one of the most common types of clips for this effect.

  1. Add the Time Remapping Effect, and watch through your clip to decide how you want the Speed to change. 
  2. Add Keyframes at the start and end of the section you want to add Time Effects to. In our example, we’re going to change the Time of the area where our performer is mid-air; the sections on either side will play at average Speed.
  3. For our example, we will slow down some of the clip, add a Freeze Frame, and a quick Time Reverse. As such, we need to make additional space in the Clip to play with. Highlight the last two Keyframes and drag them out to give you a second or two to play with. Extend your clip, so it plays through to the end.
  4. You should now have a clip that starts at Normal Speed, slows in the middle, and finishes at Normal Speed.
  5. Next, we will add our Freeze Frame; Create a Keyframe on the image you want to Freeze. Copy the Keyframe, and paste it further down the Timeline, leaving an appropriate Freeze.
  6. Click on the Graph Editor to create the Reverse section, and you will see all of your KeyFrames displayed in Graph form. On the Left is a range of Numbers, with a Line Representing 0. You will see the Freeze Frame second is a flat Line at 0; there is no Speed to the clip.
  7. To Reverse the Speed, the Clip line needs to fall below 0 on the Graph; drag your chosen Keyframes below the line and check how it looks.
  8. Finally, we are going to add a slight Ramp to the start of the section. The Clip Line will show you how the Speed is changed when you drag the Keyframe. The higher the Keyframe is in the Graph, the Faster that part will play. Play around with the Speed Ramp settings until you have created the right look, using the Handles to create softer or sharper Speed Effects.

Using Speed Ramps can be confusing and frustrating, especially when using the Graph Editor. However, it is important to remember that there are many ways to create time-based effects in After Effects. The best way to become a pro with the Graph Editor is to use it; play around with the Time Remapping After Effects tools and see what you can create.

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