---
paths:
  - "remotion_service/**"
---

# Remotion Service Rules

## Animations
- ONLY use Remotion interpolate()/spring() for all animations
- NEVER use CSS transitions, CSS animations, or Framer Motion
- All timing must be frame-based, not time-based

## Compositions
- Deterministic frame rendering: no Date.now(), no Math.random(), no network calls during render
- All data must be passed via inputProps from the server
- useCurrentFrame() and useVideoConfig() for all timing calculations

## Server
- ElysiaJS, single POST /api/render endpoint
- Flow: receive S3 path + transcription -> Remotion CLI render -> upload to S3 -> return path
- Health check: GET /health

## Captions
- All caption presets live in src/components/captions/
- Caption data format: Word[] with start/end timestamps from transcription module

## Video Inspection
- Use ffprobe (installed) to validate input video codec/resolution/fps before render
- Use ffprobe to verify output after render
- Use ffmpeg to extract single frames for visual caption verification
- Use mediainfo for detailed container metadata