Edit Slow Motion Video on iPhone: Step-by-Step

This guide shows you how to trim, adjust, and fine-tune slow-motion video on your iPhone using the built-in Photos app. You can change which parts of a clip are in slow motion, adjust the speed effect, and even restore the original speed, all without any third-party software.

What You’ll Need

• An iPhone running iOS 13 or later (the Photos app interface for slow-mo editing is consistent from iOS 13 onward).
• A slow-motion video already recorded on your iPhone (or imported from another device).

Step-by-Step

1. Open the Photos app on your iPhone. Tap the Albums tab at the bottom, then scroll down to the Media Types section and tap Slow-Mo. This shows only your slow-motion clips. Alternatively, you can find the video in your main library or in the Videos album.
2. Select the slow-motion video you want to edit by tapping its thumbnail. It will open in full screen.
3. Tap Edit in the top-right corner of the screen. The editing interface opens with the video timeline at the bottom.
4. Locate the slow-motion effect bar. Above the timeline, you’ll see a thin vertical bar with two white vertical lines (like brackets) at the top and bottom. This bar indicates which parts of the video are in slow motion. The area between the lines is the slow-motion section; outside the lines is normal speed.
5. Adjust the slow-motion range: Drag the white lines (top and bottom) to change where the slow-motion effect starts and ends. For example, drag the left line to the right to make the slow-motion start later, or drag the right line to the left to end it earlier. You can also drag the entire bar (by touching the area between the lines) to move the slow-motion segment without changing its length.
6. Change the speed effect (optional): Look for a small icon that looks like a speedometer or a clock with a circular arrow (it’s usually at the bottom-left of the timeline). Tap it to cycle through speed options: 1/4 (very slow), 1/2 (half speed), and 1/1 (normal speed). The selected speed applies to the entire slow-motion segment. Note: not all iPhones offer the 1/4 option; it depends on the model and the video’s frame rate.
7. Trim the video length (optional): To shorten the overall clip, drag the yellow handles at the very ends of the timeline (the left and right edges of the filmstrip). This cuts the video’s start and end points.
8. Preview your changes: Tap the play button to watch the video with your edits. The slow-motion effect will play in the segment between the white lines.
9. Save your edits: When you’re satisfied, tap Done in the bottom-right corner. Your changes are saved to the video. If you want to revert, tap Edit again, then tap Revert at the bottom-right to restore the original recording.

Common Mistakes

• Dragging the wrong handle: The yellow handles at the ends of the timeline trim the video length. The white lines above the timeline control the slow-motion range. Mixing them up is the most common error.
• Slow motion not applying: If you don’t see the white lines or the speed icon, the video may not actually be a slow-motion recording (it might be a regular video). Slow-motion editing only works on clips recorded with the Slo-Mo camera mode.
• Forgetting to save: If you exit the edit screen without tapping Done, your changes are lost. Always tap Done to confirm.

Tips

• Use the 1/4 speed sparingly: The 1/4 speed (quarter speed) is very dramatic and can look choppy if the original frame rate is low. For smoother results, use 1/2 speed.
• Combine slow-mo with regular speed: You can create a nice effect by having a normal-speed intro, then a slow-motion highlight, then return to normal speed. Just set the white lines to cover only the highlight moment.
• Shoot with more light: Slow-motion video requires a high frame rate, which needs more light to avoid graininess. When recording, ensure good lighting for the best quality.
• Export in high quality: When sharing, choose the highest quality option (e.g., 1080p or 4K) to preserve the smoothness of the slow-motion effect.

Troubleshooting

• The white lines don’t appear: This happens if the video is not a true slow-motion clip. Check the album: if the video is in the Slow-Mo album, it is. If not, you can’t adjust slow-motion in Photos; you’d need a third-party app.
• The video plays at normal speed after editing: Make sure you tapped Done to save. If you did, but it still plays normal, try restarting your iPhone. If the issue persists, the video file might be corrupted; try importing it again.
• Can’t find the speed icon: The speed icon (the one that cycles through 1/4, 1/2, 1/1) is only available on iPhones that support that feature. On some models, you may only have the default slow-motion speed (which is 1/2 or 1/4 depending on the recording). If you don’t see it, you can still adjust the range, but not the speed level.
• Edits are not smooth: If the slow-motion looks jerky, it might be because the original video was recorded at a low frame rate (like 120fps instead of 240fps). You can’t change the frame rate after recording, so you’ll need to re-record at a higher frame rate if available.

Frequently Asked Questions

Can I edit slow-motion video on an older iPhone?

Yes, as long as the iPhone runs iOS 13 or later, you can edit slow-motion in the Photos app. The feature has been available since iOS 11, but the interface is consistent from iOS 13 onward.

Does editing slow-motion affect the original video quality?

No, editing in Photos is non-destructive. Your original recording is preserved, and you can always revert to it by tapping Edit then Revert.

Can I make a regular video slow-motion?

No, the Photos app only allows you to edit the slow-motion effect on clips that were originally recorded in Slo-Mo mode. For regular videos, you would need a third-party app to add a slow-motion effect.

Why is my slow-motion video blurry?

Blurriness is usually caused by insufficient lighting. Slow-motion recording uses a high frame rate, which shortens the exposure time for each frame. Ensure you’re recording in a well-lit environment.

How do I share a slow-motion video without losing the effect?

When sharing, select the option to send the video as a video file (not as a link). Also, make sure the quality is set to High (e.g., 1080p or 4K) in the share sheet to preserve the slow-motion effect.

Can I change the slow-motion speed to 1/8?

No, the iPhone’s Photos app only offers 1/4, 1/2, and 1/1 speed options. For slower effects, you’d need a third-party app that supports frame interpolation.

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