Highlight finder

There's no model watching the video and deciding what's interesting, the same way Green Screen keys a colour instead of segmenting with a model and Beat Sync detects onsets instead of guessing a tempo: a real highlight-detection model is large and needs real compute, which breaks the "free, no upload, runs entirely client-side" promise every tool on this site keeps. Instead this measures the audio's loudness and the picture's frame-to-frame motion in half-second windows, combines them, and ranks the highest-scoring stretches. It has no idea whether a loud, busy moment is the best play of the game or a car alarm — it only measures loud and busy.

Loudness is the audio's RMS level per half-second window, the same measurement Noise Remover already uses to find quiet stretches, just tracking the loud ones here instead. Motion is measured by decoding the picture at a tiny size — 64 pixels wide, far too small to make out anything, plenty to measure how much is changing — and averaging the frame-to-frame brightness change, the same signal Auto-Reframe already tracks to find where the motion is. Both are normalised to the clip's own peak and combined with the loudness/motion slider. A sliding window the length of the chosen highlight duration is swept across the result, and the highest-scoring windows that don't overlap each other become the ranked candidates. This math was unit-tested standalone before being wired into this tool.

Once a range is chosen, this reuses the same lossless cutting engine as Trim and Split: compressed video and audio packets are copied straight from the original file with their timestamps shifted, so the exported clip is bit-for-bit the original picture and sound. A cut can only start on a keyframe, so the start you asked for and the start you get may move by up to a second or two — this shows exactly where it landed rather than hiding the move behind a quiet re-encode.

Measuring the audio and picture, scoring the candidates, and cutting the export all happen in this page. There is no server here to send the video to, and the page's security policy blocks any connection to anywhere but this site. Here is how that is enforced.