How to Speed Up or Slow Down Videos Using iMovie on Your MacReading Time: 3 minutes
Learn to adjust the speed of a video clip within minutes with the free iMovie app on your Mac.
Do you want to make a YouTube video with an extra punch? Perhaps you’ve made a funny home movie where you’ve played a prank on a friend or family member. Or you’re making a short instructional video for work that isn’t quite hitting the time stamp.
In such cases, you may want to speed up or slow down your videos in a video editor. Thankfully, iMovie on your Mac makes creating fast and slow-motion videos easy. Here, we’ll teach you how.
How to Use iMovie to Speed Up or Slow Down Videos
Apple’s iMovie app has a straightforward, easy-to-use interface, with most editing functions on one page. These functions do include the option to alter the speed of clips. It’s straightforward and can be very fun to play with.
If you wish to follow the guide, open up iMovie on your Mac or download iMovie from the App Store if you don’t have it installed.
If this is your first time with video editing, feel free to take a quick look at our tips for editing videos on a Mac first. Otherwise, let’s get started with preparing your clip.
Download: iMovie (Free)
Step 1: Prepare the Video Clip
First, you’ll need to add the video to your timeline. Upon launching iMovie, create a new project, and import the video. Once done, drag the video to the timeline to start the editing process.
The next step is to segment the portion of the clip you wish to speed up or slow down. To do this, scrub or play through the clip, and stop at the beginning where you intend to add the effect. Then either press Command-B or click on Modify > Split Clip from the menu bar. This will create the first cut.
Next, find the point in the timeline at which you want the video to return to normal speed. Cut here using the same method. This will create a separate clip within the timeline. You are now ready to apply the effect.
Step 2: Apply the Effect to the Video Clip
There are two ways in which you can alter the clip’s speed. You can alter it by the designated speed tab or by a slider.
You can find the Speed button—which looks like a speedometer—along with other tools in the top-right window (viewer). You have four options: slow, fast, freeze-frame, and custom.
Note the custom percentage option, which is very useful if you want a reduced or increased speed by a more specific amount. Remember that 0-99% is slower, and any value over 100% is faster.
Another interesting way to alter the speed is by a slider on the clip itself. In the top right corner of the selected clip, you may see a small gray circle with a black center. But if you don’t, select the clip you wish to alter and then press Command-R. Or, right-click the selected clip and choose Show Speed Editor from the context menu.
If you wish to have a go at a more advanced technique, follow the YouTube video tutorial on a speed ramp made by Creative Tech Lab—it shows you how to edit the speed within the clip itself.
Step 3: Customize and Tweak the Video Clip
If you think you’ve added too many effects or you don’t like the result, you can reset the clip, which is pretty easy. Simply click on the Reset option at the far right of the viewer (preview) window.
Doing this will clear all the speed alternations applied to a clip and allow you to start again. It’s worth noting that the clip size will change on the timeline too, so take care of surrounding audio and video clips.
A key point to remember is that if you have already detached the audio, you will need to alter it the same way to match the clip. Remember that altering the speed of an audio clip will also alter the pitch. This can cause voices to sound high-pitched and squeaky or low-pitched and monster-like.
Fortunately, iMovie has a handy little function that allows the clip’s pitch to remain as it should. Right next to the Reset button in the viewer, you’ll see an option called Preserve Pitch. Leaving this checked will allow the pitch of the audio clip to remain as per the original file.
When you’re done making all the adjustments, remember to save your iMovie project and then export the edited video.
Have Some Fun With Your Own Footage
If you don’t already have appropriate videos yet wish to try this technique, why not grab a camera or your smartphone and go and shoot something to use?
It could be a quick instructional video on making the perfect sandwich or a safe, practical joke on your friend. So, have some fun and jump back to the start of the guide when you are ready.