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Free Online Keyframe and GOP Analyzer for Video

Find the keyframes in a video free without uploading it. Every keyframe is listed with its second and the gap before it, and the longest gap is named, because that is what decides how far a lossless cut can slip and how well the file will stream.

Free Forever Nothing Uploaded Every Keyframe Read Only

Free Online Keyframe and GOP Analyzer for Video

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Drop a video here to list its keyframes Every keyframe with its second, and what that means for cutting and streaming. Nothing is uploaded. Select a Video MP4, MOV, WebM, MKV, AVI and more • best under 300 MB • nothing is uploaded

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What to check against

Keyframe spacing you were aiming for2.0s Streaming usually wants one every two seconds. This does not change the measurement, only what the result is compared against.

Output

Format

Quality

Size Measured on the short side, so portrait video keeps its shape.

Frame rate Dropping frames makes a smaller file. It cannot add frames that were never recorded.

Encoder effort

Encoder

File name

.mp4

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How to List the Keyframes

Drop it, run it, read the spacing.

Drop the video in It is opened by your browser and never uploaded. Only the picture stream is walked; the sound is ignored.

Say what spacing you expected Two seconds is the usual answer for streaming. This does not change the measurement, only what it is compared against.

Run it Every keyframe is reported with the second it sits at, along with the gap since the one before.

Read the spacing The shortest, longest and average gaps tell you how precisely this file can be cut and how well it will stream.

Why Keyframes Matter

Cutting, seeking and streaming all depend on them.

A cut without re-encoding can only land on a keyframe. That is why a trimmer that copies rather than rebuilds moves your in point backwards, sometimes by seconds. This list is where you find out how far backwards it can be.

Seeking is only as precise as the spacing. A player jumping to a moment has to start decoding from the keyframe before it, so a file with one keyframe every ten seconds feels sluggish to scrub even when everything else is fine.

Streaming wants regular keyframes, usually one every two seconds. Segments have to begin on one, so irregular spacing means either uneven segments or an encoder being forced to insert extras.

Irregular spacing is usually not a fault. Most encoders add a keyframe at a scene change as well as at the fixed interval, because it costs less than coding a whole new scene from the old one. Gaps shorter than the interval are normally that.

This only reads, it never writes. No new video is produced and your file is not touched.

The work happens on your own machine. Your video is opened by this page, not sent anywhere. That is why there is no upload bar, no queue and no waiting for a server. It is also why a big file leans on your own processor: nothing is being done for you somewhere else.

There is a real size ceiling, and it is your device, not us. The whole video has to fit in the browser's memory while it is being worked on, so roughly three hundred megabytes is comfortable on a laptop and far less on a phone. This page tells you where you stand the moment you pick a file.

The first run downloads the engine, later runs do not. Video work needs a real encoder, and that is a thirty megabyte download the first time you press the button. Your browser keeps it, so the second video starts straight away.

Leave the tab open. All of the work is in this page, so closing it or navigating away stops the job halfway. On a phone, switching apps can do the same thing, because the system is allowed to pause a background tab.

Key Features & Capabilities

What this tool does, and what it deliberately does not.

Nothing uploaded FFmpeg runs inside your browser as WebAssembly, so the footage never reaches a server.

Every keyframe Read from the picture stream itself rather than estimated from the file header.

The worst case named The longest gap is what decides how far a lossless cut can slip, and it is stated plainly.

Spacing summarised Shortest, longest and average gaps, plus how regular the file is overall.

A text copy The list downloads as a plain text file with every keyframe and its gap.

Read only No new video is written and your original is never modified.

About the Video Keyframe and GOP Analyzer

A keyframe is a frame that can be decoded on its own. Every other frame in a video is described in terms of the ones around it, which is most of the reason video files are not enormous, and it is also the reason a player cannot simply jump to an arbitrary moment: it has to start at the keyframe before it and work forwards.

That one fact explains several things people find confusing. A trimmer that promises no quality loss can only cut on a keyframe, so an in point lands earlier than you asked, sometimes by several seconds. Scrubbing feels heavy on a file with sparse keyframes even when the machine is fast. Streaming platforms ask for a keyframe every two seconds because segments have to begin on one.

This page walks the picture stream and lists every keyframe with the second it sits at and the gap since the last one. The longest gap is the number that matters most, because it is the worst case for all three of those problems.

Irregular spacing is usually not a fault. Encoders add keyframes at scene changes as well as at their fixed interval, because starting a new scene fresh costs less than describing it in terms of the old one. Nothing here is written: the file is read and reported on, and a text copy is offered.

Frequently Asked Questions

GOP length, cutting without re-encoding, and streaming.

Drop it here and press the button. Every keyframe is listed with the second it sits at and the gap since the one before it.

Because a cut that does not re-encode can only start on one. If your trim keeps landing earlier than you asked, the keyframe spacing is why.

The run of frames from one keyframe up to the next. A short GOP makes a file easier to cut and seek; a long one makes it smaller.

About one keyframe every two seconds is the usual target for streaming. For editing, shorter is friendlier; for pure file size, longer is cheaper.

Most encoders add a keyframe at a scene change as well as at the fixed interval, because that costs less than coding a whole new scene from the old one.

No. The keyframes are read out of the file in this tab. Nothing about your video is uploaded.