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name: remotion-video-builder description: Use when building, reviewing, or refactoring a Remotion project, especially parameterized launch or demo videos with shared props schemas, calculateMetadata, Sequence and Series timing, multiple aspect ratios, terminal or footage layers, and render scripts. Prefer official Remotion docs or MCP for API details because package behavior may change.

Remotion Video Builder

Your Remotion knowledge may be stale. When exact API behavior matters, prefer the official remotion-documentation MCP server or the docs at remotion.dev.

Start Here

• If the project does not exist yet, scaffold it with npx create-video@latest and prefer the blank template.
• Keep every remotion and @remotion/* package on the exact same version and avoid caret ranges.
• Standard entry shape:
  • src/index.ts calls registerRoot()
  • src/Root.tsx registers all videos with <Composition> or <Still>

Build Order

1. Model the input contract first:
   • top-level props schema
   • timeline or event data
   • render profile
2. Define shared props with zod and pass the schema to each <Composition>.
3. Use calculateMetadata to derive durationInFrames, width, height, transformed props, and defaultOutName.
4. Build the scene structure with <Series> for narrative order and <Sequence> for overlays, entrances, footage windows, and callouts.
5. In Remotion v4.x projects, explicitly set premountFor on <Sequence> elements that need assets loaded before they appear.
6. Add sample data and render scripts before polishing animation.

Defaults And Rules

• Default to fps={30} and 1920x1080 for landscape unless the brief says otherwise.
• Use AbsoluteFill for layering.
• Use staticFile() for anything coming from public/.
• Use useCurrentFrame() and useVideoConfig() for frame-based logic.
• Prefer subtle motion:
  • spring() with high damping
  • interpolate() with clamping
• Do not use Math.random(). Use random(seed) from remotion.
• Keep text animation simple and legible.
• Keep landscape and vertical outputs on the same business logic unless the brief truly requires divergence.

Parameterized Video Checklist

• One shared top-level z.object() schema
• defaultProps matching the component prop shape
• calculateMetadata returning dynamic duration or dimensions when inputs require it
• Sample JSON or TypeScript data for local preview
• Render scripts for every target output

Footage Strategy

Support at least these modes when footage is optional:

• none
• placeholder
• real

The timeline and overlays should still render when no real footage exists.

Millrace Launch Video

If the request is about Millrace or the launch video pipeline, read references/millrace-launch-video.md before implementing.

References

• references/remotion-core.md
• references/millrace-launch-video.md