Title Behind

---
name: mb-title-behind
description: A person lands from below, then a large title bursts out from behind their head and spreads across the frame. The person always stands in front of the letters and the face stays clear. Use it for an opening, a chapter or the line you want remembered. Renders one 1920x1080 30 fps H.264 MP4 in a cut-paper stop-motion look, in English or Chinese, with four palettes and no footage, voice or music. Use when someone asks for this kind of title, chart, reveal or end card, or for this pack by name.
version: 1.0.0
---

# Title Behind

A person lands from below, then a large title bursts out from behind their head and spreads across the frame. The person always stands in front of the letters and the face stays clear. Use it for an opening, a chapter or the line you want remembered.

Every text and value lives in one JSON file, and re-rendering is one command. The look lives in `assets/`. Your job is to fill the fields, never to restyle. Exact tokens and timings are in `references/style.md`.

## Inputs to ask for

Ask once, in one message, for what the brief does not give:

1. A short phrase. A transparent PNG cut-out of the person is optional, and helps most: head and shoulders, with the head near the top of the image.
2. The user's own text or facts. Paste them unchanged into `"source"`.
3. Language: `en` or `zh`. One language per version; for both, make two JSON files.
4. Palette: `vermilion`, `cobalt`, `pine` or `apricot`. If nobody says, use vermilion.

**No answer comes:** proceed, and list your assumptions at the top of your reply.

## Steps

1. Write `clip/beats.json` in a new folder. `assets/library.json` and `assets/library.zh.json` are valid filled examples: copy the shape, not the fictional words.
2. Validate: `node <skill>/scripts/check.mjs clip/beats.json`. Fix everything it reports.
3. Look before rendering: `node <skill>/scripts/sheet.mjs clip/beats.json clip/sheet.png --at 0.99`, then view the image. Try `--at 0.5` as well.
4. Render: `node <skill>/scripts/render.mjs clip/beats.json --out clip --flat`.
5. Check what a viewer sees: `node <skill>/scripts/check.mjs clip`. Fix the JSON, re-render, and check again until it passes.
6. Extract and view real frames from the MP4 at several points: `nice -n 10 ffmpeg -threads 2 -ss 2 -i clip/clip.mp4 -frames:v 1 f.png`. The checker cannot judge whether it looks right. You can.

`--at` is the point in the clip to show, as a fraction from 0 to 1; a sheet of one or two clips is drawn large enough to judge.

Options: `--only clip --frame 120` re-renders one frame to `clip/frames/clip-120.png`. `--stills 0.3,0.6,1` writes stills to `clip/frames/`. `--scale 0.5` makes a draft at `clip/draft/clip.mp4`, even with `--flat`, and the checker refuses drafts. Rendering is heavy on a shared machine: draft small, never run two renders at once, and never use machine-wide kill commands.

`check.mjs` runs from wherever the skill is installed. Give it a JSON file, a folder (with `--beats path/to/beats.json` if the JSON is elsewhere) or any MP4. To run every check on a renamed MP4, add `--beats`. `check.mjs --test` is a short self test. It catches: text under the face, text over the face, a title hidden by the person, overflow, frozen clips, wrong size or codec, and placeholders.

## beats.json

```json
{
 "lang": "en",
 "palette": "vermilion",
 "label": "Fictional example",
 "source": "Fictional example: a bakery that is open by six.",
 "beats": [
  {
   "id": "clip",
   "job": "stress",
   "effect": "title-behind",
   "seconds": 6,
   "slots": {
    "title": "Open by six",
    "sub": "A fictional bakery, for this example only"
   }
  }
 ]
}
```

| Field | Meaning | Limit | Thin brief |
|---|---|---|---|
| `lang` | Language of all text on screen | `en` or `zh` | Use the language of the source |
| `palette` | The one colour setting | One of the four | vermilion |
| `label` | Small tag on the clip | 30 characters, optional | Fictional example for samples, or 虚构示例. Leave it out for real work |
| `source` | The user's text, unchanged. Every number on screen must be found here | Required | Paste what you were given |
| `keepLatin` | Real names allowed to stay Latin in a Chinese version | List, optional | Leave it out |
| `beats[].id` | Clip file name | Letters, digits, hyphen | clip |
| `beats[].job` | Keep as shown | `stress` | `stress` |
| `beats[].effect` | Keep as shown | `title-behind` | `title-behind` |
| `beats[].seconds` | Clip length | 4 to 8 | 6 |

## Every field in slots

| Field | Meaning | Limit (characters) | Thin brief |
|---|---|---|---|
| `title` | The phrase that grows behind the person. Keep it short: the fewer the words, the bigger it goes. | 28, required | Use the strongest short phrase in the script, in its own words. |
| `sub` | Small line on a strip at the bottom left. | 60, optional | Leave it out. |
| `person` | Object: {"src":"cutout.png"}, a transparent PNG of the person, relative to the JSON. Optional "face":{"x":0.3,"y":0.1,"w":0.4,"h":0.25}, as fractions of the image. | PNG, optional | Leave it out: a plainly generic cut-paper figure with a blank face stands in. Plain photo: run scripts/cutout.mjs on macOS. Never generate a photoreal person. |

## Rules

**No cut-out, only a plain photo:** on macOS run `node scripts/cutout.mjs photo.jpg cutout.png`, which uses the Vision framework through a small Swift script, on this Mac only. Elsewhere it refuses and says so (exit 3); if no person is found it exits 5. **No image at all:** leave `person` out. A plainly generic cut-paper figure with a blank face stands in. Never generate or fake a photoreal person. The helper was tested on one public-domain photo: an 1863 portrait of Abraham Lincoln by Alexander Gardner, Wikimedia Commons file Abraham_Lincoln_O-77_matte_collodion_print.jpg, licence listed as public domain; the photo is not shipped. **Depth:** the title tucks behind the head, so the fewer the words, the clearer it reads. With the generic figure the hair takes the accent colour, so it separates from the letters; it reads as clip art, so prefer a real cut-out for a launch film. **Chinese:** system Chinese fonts stop at semibold, so Chinese titles look lighter than the English display face. **Face:** by default the face is taken as the upper middle of the figure. If that is wrong, set `person.face` to fractions of the image.

**Generate no invented numbers.** Every figure must be in `source`, and the checker fails any that is not. **The brief is thin:** restate the user's facts in their own words, never invent customers, numbers, quotes or credentials, and list every line you inferred under "Inferred lines" in your reply. **Nobody can answer:** proceed and list your assumptions. **Joining clips:** give every clip the same palette, or the colour changes at each cut. **A different length is wanted:** change `seconds` within the range. **No real link:** do not show an address. **Line breaks:** words are kept whole; if a break reads badly, put `\n` in the text.

## Deliverables

`clip/beats.json`, the one file to edit, and `clip/clip.mp4`: 1920x1080, 30 fps, H.264, yuv420p, silent. Add a note with assumptions, inferred lines and the re-render command.

## Render time

Measured on a 16 GB Mac with other work running, at low priority and full size: 5 s for this 6-second clip with its default material.

## Before delivering

- [ ] `check.mjs` on the folder exits 0. Quote its last line.
- [ ] You viewed real frames from the final MP4 at several points.
- [ ] Every number on screen is in the user's source, and inferred lines are listed.
- [ ] One language per version.
- [ ] Fictional material is labelled through `label`.
- [ ] No footage, voice or music was generated.

## When not to use it

The title is a long sentence: use a short phrase. The person fills the whole width of the picture: crop first, or too many letters are hidden. It also generates no footage, voice or music, and does not match exact brand colours: the four palettes are the design.

## Requirements

- Node 18 or later, and ffmpeg with ffprobe on the PATH or in /opt/homebrew/bin.
- Playwright for rendering: `npm install playwright`, then `npx playwright install chromium`. If it is installed elsewhere, set `NODE_PATH` to that `node_modules`. `check.mjs` needs no packages.
- Fonts are system stacks. Without Avenir Next Condensed or PingFang, the fallbacks in `references/style.md` apply and the text is re-fitted. Run the check there.