Guide
How to fix flickering slow-motion video on iPhone
You filmed something great in slow motion, played it back, and the whole picture is pulsing, or dark bands are rolling through it. The good news is that flicker is one of the more fixable problems in video: it's a change in brightness from frame to frame, and software can measure that change and undo it. Here's how to do it on your iPhone, without a computer.
Open the clip in a deflicker app such as Deflicker, keep the default settings (On iPhone, Medium strength, Smart method), tap Remove flicker, compare the result and save it to Photos. If deep flicker or uneven patches of light remain, run the clip through Fusion, the stronger cloud engine.
First, work out what kind of flicker you have
Play the clip a couple of times and watch the light rather than the subject. Slow-motion flicker usually shows up in one of four ways, and knowing which one you have helps you pick the right setting later.
- Whole-frame pulsing. The entire picture gets brighter and darker in a steady rhythm. This is the most common kind, typical of a room lit by one type of light.
- Bands. Darker stripes sit across the frame or crawl through it. They come from the camera's rolling shutter reading the sensor line by line while the light pulses. In clips filmed with the phone upright, the stripes usually run from top to bottom.
- Patchy flicker. Different parts of the frame pulse out of step with each other. You see this in big spaces such as gyms, warehouses and ranges, where fixtures can run on different phases of the power supply, or where two kinds of light mix.
- Color flicker. The tint shifts along with the brightness, often towards green or magenta. Fluorescent tubes and some LEDs do this because their colors don't all pulse in exactly the same way.
If you're curious why this happens at all, why slow-motion video flickers explains the physics in plain terms.
Step by step: remove flicker with Deflicker
These steps use Deflicker, our iPhone app built for exactly this job. The on-device fix is free to try; exports carry a watermark until you upgrade to Pro.
Get the clip ready in Photos
Make sure the flickering video is in your Photos library. If only part of a long clip matters, trim it first: tap Edit and drag the ends of the timeline. Deflicker picks up the edited version, so there is less to process.
Open Deflicker and choose the video
Tap Choose a video and pick the clip. It loops on the next screen so you can see the flicker you are about to fix.
Pick the engine
Choose On iPhone or Fusion. On iPhone is quick, private and right for most clips. Fusion is the stronger option for deep or patchy flicker; it runs on our GPUs and uses the Fusion clips included with Deflicker Pro.
Set strength and method
For the on-device engine, Medium strength suits most clips. Light is gentler and keeps real lighting changes, like a lamp switching on; Strong is for heavy flicker. Under Method, Smart is the default and the right choice almost every time. Bands targets rolling stripes, Deep rebuilds each frame's tone balance, and All runs every method so you can pick the best result.
Remove the flicker
Tap Remove flicker, or Remove flicker with Fusion. With the on-device engine, keep the app open while it works. With Fusion you only need to stay in the app for the upload, and the button shows how many Fusion clips the video will use before you start.
Compare before and after
Drag the line across the preview: the original is on the left and the fixed video on the right, both playing in sync. To see the untouched clip full-frame, touch and hold the Hold for original button.
Save to Photos
Tap Save to Photos. The fixed video is saved as a new clip in your library, and the original stays as it was.
Which settings for which flicker
The defaults handle most clips. When they don't, this is where to go next.
| What you see | Try first | If it isn't enough |
|---|---|---|
| Whole frame pulsing | Smart method, Medium strength | Strong, then Fusion |
| Stripes or rolling bands | Smart (it works area by area) | Bands method, then Fusion |
| Patches flickering out of sync | Smart | Fusion |
| Tint shifting with the flicker | Deep method | Custom with color flicker correction on, or Fusion |
| A real lighting change you want to keep | Light strength | Custom with less smoothing |
Not sure? Choose All under Method. Deflicker runs every on-device method on the clip so you can flip between the results and keep the best one. It takes roughly four times as long, so it's worth it for short clips.
What deflickering can and can't fix
Deflickering evens out brightness. It works best when every frame still holds the detail and only the exposure level is wrong. A few things limit how far any tool can go:
- Clipped highlights. If a lamp or a white wall is blown out to pure white in the bright frames, there's no detail left to bring back. The flicker around it can be smoothed, but the clipped area stays flat.
- Very dark frames. When the camera caught the light near the bottom of its pulse, brightening those frames also brightens their noise. Deep flicker can leave a slightly grainier result.
- Screens in the shot. TVs, monitors and LED signs refresh in their own pattern. They can flicker for different reasons than room lighting and may not clean up completely.
Fast motion is the other classic problem: simple tools mistake a moving subject for a brightness change and make the area around it pump. Deflicker's Smart method follows the picture area by area to avoid that, and Fusion goes further by tracking every pixel across frames.
Prefer to fix it on a computer?
If you already edit on a Mac or PC, there are good desktop routes too: a dedicated plug-in, DaVinci Resolve Studio's Deflicker effect, or the free ffmpeg command line. We compare them honestly in how to deflicker video without After Effects. For a clip that's already on your phone, though, fixing it there skips the export and import round trip.
Stop it happening next time
A few habits prevent most flicker before it's recorded: film in daylight or under steady lights when you can, use 120 fps rather than 240 fps if you're in a 60 Hz country, and avoid dimmed LEDs. The details, including flicker-safe shutter speeds for 50 Hz and 60 Hz power, are in how to prevent flicker when filming on iPhone. And if LED lighting is your main problem, see how to remove LED and fluorescent flicker.
