# Video Splitter

Cut a long video into clips that begin at shot changes rather than on a fixed interval, ranked by picture quality.

Runs entirely in the browser through WebCodecs and WebAssembly. No upload, no account, no size limit
imposed by a plan, no watermark — because there is no server involved.

Page: https://life2film.com/tools/video-splitter/

## What matters

- Shot boundaries come from the Life2Film engine (Rust compiled to WebAssembly), not from a timer.
- Sampling rate dominates accuracy: at 2 samples/second boundaries land 1-3 seconds out; at 10/second they land on the frame. All sixteen detection algorithms were wrong the same way at the low rate.
- Uses a coarse pass to find candidates, then a tight pass at ten times the resolution around each one.
- Clips never cut inside a shot; short tails are absorbed into the previous clip.
- Optional 9:16 crop takes the centre of the frame, there is no face tracking.

## From code

```js
// Shot detection uses the Life2Film engine:
// https://life2film.com/wasm/va_wasm.js
const engine = await import('https://life2film.com/wasm/va_wasm.js');
await engine.default({ module_or_path: 'https://life2film.com/wasm/va_wasm_bg.wasm' });

// pixels: centre-column mean RGB per sampled frame, timestamps in seconds
const { scenes } = JSON.parse(engine.detect_scenes_slick(JSON.stringify({
  pixels, timestamps, duration, algo: 'adjacent_diffs',
})));
```

## Questions

**How is this different from other video splitters?**

Most cut every N seconds, so a clip can start halfway through a sentence and end mid-gesture. This one finds the cuts the video already has (the shot changes) and builds clips out of whole shots. You still choose roughly how long a clip should be; the boundaries land on the nearest real change instead of on a stopwatch.

**Is my video uploaded?**

No. The browser decodes it, WebAssembly analyses the frames, and the clips are re-encoded locally with WebCodecs: the same hardware path your browser uses to play video. Nothing is sent anywhere, which is also why there is no length limit imposed by a plan, no queue and no watermark.

**What are the stars next to each clip?**

The engine scores every sampled frame for sharpness, exposure, contrast, colourfulness and detail, and each clip gets the duration-weighted average of the shots inside it. The stars are relative to the best clip in this video, not an absolute scale, they are a suggestion of where to look first, not a verdict on what is interesting.

**Will the vertical crop cut people out of frame?**

It takes the centre of the frame, which is right most of the time and wrong when the subject is off to one side. There is no face tracking here yet, so check the previews before posting. If a clip is framed wide, it is usually better to crop it by hand.

**How long does it take?**

Analysis takes a few seconds per minute of video. Encoding is the slow part and depends on your machine, expect roughly real time or better for 1080p on a recent laptop, since it uses the GPU where available. Clips are written one at a time so you can start downloading before the rest finish.

**Which files work?**

MP4 and MOV with H.264, and WebM, whatever your browser can both decode and encode. Camera-native formats like ProRes or raw usually cannot be opened by a browser; transcode a proxy first.

## Related

- [Trim Video](https://life2film.com/tools/video-trimmer/): Drag the handles to the part you want, preview it, save it. Audio stays in sync.
- [Compress Video](https://life2film.com/tools/video-compressor/): Make a file smaller and see exactly what it cost. No size limit, because there is no server.
- [Video to MP3](https://life2film.com/tools/video-to-mp3/): Pull the audio out of a video and keep it as MP3, WAV or OGG.
- [Convert Video](https://life2film.com/tools/video-converter/): MP4, WebM and MOV in any direction, or pull the audio out as WAV.
- [BPM Detector](https://life2film.com/tools/bpm-detector/): Find a track’s tempo and the time of every beat, then send the grid to Resolve, Premiere, Final Cut or Audacity as markers.
- [Scene Detector](https://life2film.com/tools/scene-detector/): Find every cut in a video and get the shot list with thumbnails, timecodes and quality scores.

- The engine as a package: https://life2film.com/engine/
- Site overview for agents: https://life2film.com/llms.txt
- Every tool page is available as markdown by appending `.md` to its address, or by requesting it
  with `Accept: text/markdown`.

---
Life2Film — on-device video montage. https://life2film.com/