OneTaskBy Tim King · Updated
Frame Difference Viewer
Compare Two Video Frames to Spot Scene Cuts, Flicker and Motion
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How the Frame Difference Viewer works
This frame difference viewer compares one moment of a video with a moment just after it and lights up every pixel that changed. Drag Position to scrub, choose how far apart the two frames are, and read the verdict: static, motion or a likely cut. Everything runs in your browser.
Two frames that look identical to the eye can differ in thousands of pixels, and two frames that look different can share most of their picture. Subtracting one from the other shows the truth. Editors use it to find hidden cuts, encoders to spot flicker, and anyone checking a looping clip to see whether the last frame really matches the first.
How the frame difference viewer works
The video is seeked to the Position you choose, and that frame is copied. It is then seeked forward by the gap and the second frame is copied. For every pixel the tool takes the absolute difference of the red, green and blue values and averages them. A pixel counts as changed when that average is above 12 on the 0–255 scale, which ignores most compression noise.
In Difference view, unchanged areas are black and changed areas glow, brighter for bigger changes. Boost multiplies the difference so small movements become visible. In Overlay view, the second frame is dimmed and changed pixels are tinted red, so you can see what moved in context.
Choosing the gap
| Gap | At 30 fps | Good for |
|---|---|---|
| 1 frame | 33 ms | Cuts, flicker, dropped or duplicated frames |
| 5 frames | 167 ms | Slow motion, camera shake |
| 0.5 seconds | 500 ms | Gradual changes, slow pans |
| 1 second | 1000 ms | Time-lapse and security footage |
The tool assumes 30 frames per second for the frame-based gaps. At 60 fps, "1 frame" is really two frames apart; at 24 fps it is slightly less than one frame step, which is still fine.
Find biggest change
The action samples 120 evenly spaced points through the clip at a small size, measures the difference at each, and jumps Position to the largest. In edited footage that is almost always a hard cut. In a single continuous shot it is the moment of fastest motion.
Tips and pitfalls
A whole frame lit up means a cut or a flash. Over 60% of pixels changed in one frame step is rarely motion; it is an edit, a camera flash or an exposure jump.
Nothing changed at all can be a problem too. Zero difference across one frame step in moving footage usually means a duplicated frame, often from a frame rate conversion.
Noise looks like change. Dark, grainy footage shows a speckled difference everywhere. Lower Boost before deciding something moved.
How to read the result
The stats show the two times compared, the share of pixels that changed, the mean difference on the 0–255 scale and a verdict. Download saves the current view as a PNG.
FAQ
What does the frame difference show?
It shows how much each pixel changed between two moments of the video. Black means the pixel stayed the same, and brighter colours mean bigger changes, so moving objects, cuts and flicker stand out against a still background.
How do I find a scene cut in a video?
Press Find biggest change. The tool samples 120 points through the clip and jumps to the one with the largest difference, which is usually a hard cut. Then set the gap to 1 frame and step Position to see the exact frame.
Why does the whole picture show some change?
Video compression and sensor noise change pixel values slightly in every frame. The tool ignores differences of 12 or less, but grainy or dark footage still shows a faint speckle. Lower Boost to make only real movement stand out.
Is my video uploaded to compare frames?
No. The video is decoded and compared by your own browser, and the difference image is drawn on your device. Nothing is sent to a server, so private and unreleased footage stays with you.
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