Capturing videos has come a long way since the first film camera was made. Now, consumer digital video cameras can record high-resolution footage at frame rates previously limited to high-budget productions. Even your smartphone can shoot slow-motion videos. And one of the best ways to make those even more amazing is by adding a variable speed.
Speed ramping is used a lot of because it helps to focus your audience on something specific. Clips play at normal speed, then slow down and go back to normal speed, or the other way around. You can find good examples of time-remapping in movies like The 300, Snatch, or Sherlock Holmes.
The common technique that a lot of editors use is to cut clips into three sections. The first and last sections are at normal speed, while the middle section is either sped up or slowed down. The problem with this method is that the speed change is instant and can be a little jarring. Time-remapping, on the other hand, allows you to vary the speed of your clips with the use of keyframes. This gives you more control over how the speed changes from normal to slow or fast.
First, increase the height of the video track where your clip is. The easiest way to do this is by placing your mouse pointer on a track header and scrolling on your mouse. Doing this will help you adjust clip keyframes a lot more easily.
Next, select your clip on the timeline and, right-click, and choose Show Clip Keyframes > Time Remapping > Speed, or simply place your mouse pointer on top of the clip’s Fx badge and choose Time Remapping > Speed.
This allows you to view the speed keyframes of a clip. You’ll know if you’ve got it right because the horizontal white band will go from the upper portion to the middle.
Position the playhead to where you want the speed change to start and create a keyframe. Adding keyframes can be done in two ways: by using the Pen tool and clicking on the Speed keyframe or by using the selection tool and Ctrl-click or Command-clicking on the rubber band. Do this again, this time creating a keyframe where you want the speed change to end.
Select the white rubber band in the middle of the keyframes and drag it down.
This will decrease the playback speed of that portion. Pressing Shift while dragging will change the values to 5% increments.
This is what I have so far. The clip starts at a normal speed, slows down in the middle, and then goes back to normal speed.
This is the initial result of my time-remapping. What I like about this technique is that it’s very easy to revise it if needed. All you need to do is drag the white rubber band again to your desired speed, and you’re done.
You could stop here, but let’s take it to another level. Right now, the speed change is instantaneous and, as mentioned earlier, a little jarring. By adding a speed transition, we can make the shot even better.
Alt-click or Option-click the keyframe to split it, then drag the sides to separate it. You’ll notice that the white line now ramps down, which makes the speed transition smoother.
While you’re separating the keyframes, you’ll also notice that the program monitor updates and shows you the start and end of the ramp.
You should now have something like this:
This is the result of our speed ramp.
As a final optional step, you can smooth out the ramp to get an even better result. Click on the keyframe to show the Bezier handles and drag them to smooth it out.
If you want to change the in and out sections of the speed change, click on the speed-control track between the split keyframes and drag it. This will allow you to move the keyframes later or earlier in the clip.
And here’s our final result:
Using variable speed ramps is a great technique to add more drama into your shot. Just don’t be tempted to use time-remapping for the sake of doing it — always make sure that it, like every other creative choice helps add to the story and movement of your film.