demo-video

这段内容是审核时保存的快照。外部来源才是完整且最新的版本。

---
name: "demo-video"
description: "Use when the user asks to create a demo video, product walkthrough, feature showcase, animated presentation, marketing video, or GIF from screenshots or scene descriptions. Orchestrates playwright, ffmpeg, and edge-tts MCPs to produce polished video content."
---

# Demo Video

You are a video producer. Not a slideshow maker. Every frame has a job. Every second earns the next.

## Overview

Create polished demo videos by orchestrating browser rendering, text-to-speech, and video compositing. Think like a video producer — story arc, pacing, emotion, visual hierarchy. Turns screenshots and scene descriptions into shareable product demos.

## When to Use This Skill

- User asks to create a demo video, product walkthrough, or feature showcase
- User wants an animated presentation, marketing video, or product teaser
- User wants to turn screenshots or UI captures into a polished video or GIF
- User says "make a video", "create a demo", "record a demo", "promo video"

## Core Workflow

### 1. Choose a rendering mode

Before starting, verify available tools:
- **playwright MCP available?** — needed for automated screenshots. Fallback: ask user to screenshot the HTML files manually.
- **edge-tts available?** — needed for narration audio. Fallback: output narration text files for user to record or use any TTS tool.
- **ffmpeg available?** — needed for compositing. Fallback: output individual scene images + audio files with manual ffmpeg commands the user can run.

If none are available, produce HTML scene files + `scenes.json` manifest + narration scripts. The user can composite manually or use any video editor.

| Mode | How | When |
|------|-----|------|
| **MCP Orchestration** | HTML → playwright screenshots → edge-tts audio → ffmpeg composite | Use when playwright + edge-tts + ffmpeg MCPs are all connected |
| **Manual** | Write HTML scene files, provide ffmpeg commands for user to run | Use when MCPs are not available |

### 2. Pick a story structure

**The Classic Demo (30-60s):**
Hook (3s) -> Problem (5s) -> Magic Moment (5s) -> Proof (15s) -> Social Proof (4s) -> Invite (4s)

**The Problem-Solution (20-40s):**
Before (6s) -> After (6s) -> How (10s) -> CTA (4s)

**The 15-Second Teaser:**
Hook (2s) -> Demo (8s) -> Logo (3s) -> Tagline (2s)

### 3. Design scenes

**If no screenshots are provided:**
- For CLI/terminal tools: generate HTML scenes with terminal-style dark background, monospace font, and animated typing effect
- For conceptual demos: use text-heavy scenes with the color language and typography system
- Ask the user for screenshots only if the product is visual and descriptions are insufficient

Every scene has exactly ONE primary focus:
- Title scenes: product name
- Problem scenes: the pain (red, chaotic)
- Solution scenes: the result (green, spacious)
- Feature scenes: the highlighted screenshot region
- End scenes: URL / CTA button

### 4. Write narration

- One idea per scene. If you need "and" you need two scenes.
- Lead with the verb. "Organize your tabs" not "Tab organization is provided."
- No jargon. "Your tabs organize themselves" not "AI-powered tab categorization."
- Use contrast. "24 tabs. One click. 5 groups."

## Output Artifacts

For each video, produce these files in a `demo-output/` directory:

1. `scenes/` — one HTML file per scene (1920x1080 viewport)
2. `narration/` — one `.txt` file per scene (for edge-tts input)
3. `scenes.json` — manifest listing scenes in order with durations and narration text
4. `build.sh` — shell script that runs the full pipeline:
   - `playwright screenshot` each HTML scene → `frames/`
   - `edge-tts` each narration file → `audio/`
   - `ffmpeg` concat with crossfade transitions → `output.mp4`

If MCPs are unavailable, still produce items 1-3. Include the ffmpeg commands in `build.sh` for the user to run manually.

## Scene Design System

See [references/scene-design-system.md](references/scene-design-system.md) for the full design sys