---
name: beat-cut
title: Cut on the beat
summary: Find the tempo and every beat of a song and land each cut, caption and action peak on the music.
tags: [edit, music]
---
# Cut on the beat

1. **Detect beats** with an onset/beat tracker (e.g. librosa `beat_track`) on the full mix. Note the BPM and the time of the first downbeat.
2. **Build a grid.** Beat *k* is at `t0 + k × 60 / BPM`. Bars are every 4 beats.
3. **Snap cuts.** Every shot start goes to the nearest beat; section changes go to downbeats (bar starts).
4. **Pace by section.** Verses: cut every 2 bars. Pre-chorus: every bar. Chorus: every 2 beats. Drops: hit the first downbeat with the biggest shot.
5. **Land the action.** If a shot's action peak (arrow release, door slam) misses a beat by less than 0.3 s, retime the clip between 0.7× and 1.25× so the peak lands.
6. **Captions on beats too.** Big words appear on the beat they are sung, not before.

Our free in-browser Beat Cutter does steps 1–3 for any song: nightshift.fans/#tools