A VideoToFrames alternative that never uploads the video
People searching this way want to turn a video into a set of still images, usually for thumbnails, contact sheets or frame-by-frame review.
Convertto extracts still frames from a video inside your browser tab. FFmpeg is compiled to WebAssembly and runs on your own machine, so the video file is never uploaded. Choose how many frames you want and they are sampled across the clip, with the first picked by FFmpeg's thumbnail filter so it is a representative frame rather than a black opening one.
- Engine
- FFmpeg compiled to WebAssembly, running in a Web Worker
- Video uploaded
- None. The file is read from disk into the tab
- First run
- Downloads about 30 MB of FFmpeg core, then cached
- Cost
- Free, no sign-up, no length limit imposed
What you are looking for, and the tool that does it
| The job | Convertto tool | What it does |
|---|---|---|
| Frames as individual images | Video to Frames / Images | Extracts frames at any interval as JPG or PNG images |
| A few representative stills | Video Frame Extractor | Picks a representative first frame, then samples further frames across the clip |
| An animated GIF instead | Video to GIF Converter | Turns a clip into an animated GIF, with control over frame rate and size |
| An animated WebP instead | Video to WebP Animation | Turns a short clip into an animated WebP, far smaller than a GIF |
| A shorter clip first | Video Trimmer | Cuts a clip out by start and end time, without uploading it |
| Just the audio | Video to MP3 Converter | Extracts the audio track as MP3, WAV, AAC or OGG |
Why the first frame is usually the wrong frame
Taking frame zero as a thumbnail almost always produces a black rectangle, because most footage opens on a fade, a slate or an empty shot. FFmpeg's thumbnail filter exists for this: it buffers a window of frames and picks the one least like the average, which in practice means the one with the most detail and contrast. That is what the frame extractor uses for its first pick.
How many frames to ask for
- One thumbnail: ask for one and let the thumbnail filter choose it.
- A contact sheet: eight to twenty frames sampled evenly gives a readable overview of a clip of any length.
- Frame-by-frame review: ask for a high count over a short trimmed section rather than over the whole video, or you will extract thousands of images.
PNG or JPG
PNG is lossless, so a PNG frame is exactly what the decoder produced and is the right choice for analysis, for compositing, or when the frame will be edited further. JPG is far smaller and is the right choice for a contact sheet or a thumbnail that will be looked at and discarded. Extracting to JPG does add a second lossy step on top of the video codec's own compression, which shows up as extra artefacts around sharp edges and text.
What running locally costs and buys
The cost is a one-time download of roughly 30 MB of FFmpeg WebAssembly on first use, and extraction speed bounded by your own CPU rather than a server's. What it buys is that the video itself never moves. For recorded meetings, unreleased footage, medical or legal video, or anything under an NDA, that trade is usually the right way round, and it removes the upload wait for large files entirely.
Related media tools
The rest of the set is in audio and video tools: video compressor, video converter, media file info for reading a file's streams and codecs, and video to subtitles for transcription.
Frequently asked questions
Is my video uploaded?
What is the 30 MB download on the first run?
Can I extract every frame of a video?
Why is the first frame black on other tools but not here?
What formats can it read?
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