# Zoom Punch

> zoom-punch

- Skill: `jperrello/zoom-punch` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add jperrello/zoom-punch`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jperrello/zoom-punch/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jperrello (https://skillmd.com/u/jperrello)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jperrello/zoom-punch

---


# zoom-punch

A punch-in zoom is the cheapest "wake up" beat in shorts editing: a sharp ~10%
zoom punctuating an emphasis word. This skill places 1–4 of them
deterministically.

## Invoke

```
.claude/skills/zoom-punch/zoom-punch.sh <in.mp4> <transcript.json> <out.mp4> [strength=0.10]
```

- `in.mp4`: the 1080x1920 vertical clip (post fill-vertical)
- `transcript.json`: the clip-local word-timed transcript
- `strength`: zoom amount (0.10 = 10% punch)

## Placement rules

- candidate = loudest per-second RMS buckets (`pick-segments/rms.py`)
- snapped to the nearest word start within 0.6s — the punch lands ON a word
- first 2.8s excluded (title card) and last 2s excluded
- min 4s apart, count = clamp(dur/12, 1, 4)
- pulse: 0.1s attack -> ~0.35s hold -> 0.18s release, upper-third crop bias

## Chain position

After `fill-vertical`, BEFORE `broll-composite` (cutaways replace the full
frame and must not be warped by a punch) and `burn-subtitles` (captions must
not wobble). Orchestrators treat it as non-fatal: on failure the vertical clip
passes through unzoomed. Disable with `ZOOM_PUNCH=0`.

## Output

1080x1920 mp4, video re-encoded, audio stream-copied. Idempotent via
`<out>.zpmeta`. No punch candidates -> passthrough copy.