# Remotion Video
> This skill should be used when the user asks to "make a video with Remotion", "create a programmatic/data-driven video in React", "render an MP4/GIF from code", "animate with useCurrentFrame/interpolate/spring", "sync video to audio/beats", or "render a templated video per record headlessly". Covers building React compositions and rendering them via CLI or @remotion/renderer.
- Skill: `2233admin/remotion-video` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add 2233admin/remotion-video`
- Raw SKILL.md: https://api.skillmd.com/api/skills/2233admin/remotion-video/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: 2233admin (https://skillmd.com/u/2233admin)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/2233admin/remotion-video
---
# Remotion (Programmatic Video)
Build real MP4/GIF/WebM videos in React. Every frame is a pure function of `useCurrentFrame()`, so output is deterministic, scrubbable, diffable, and renderable in CI. The code-first alternative to After Effects for templated and data-driven motion graphics.
## When to use
- Render MP4/GIF/WebM from code (social clips, title cards, explainers).
- Templated/data-driven videos: one composition, many outputs from props (per-user, per-record, per-row of a CSV/DB).
- Motion graphics that must be versioned, code-reviewed, and rendered in CI without a GUI.
- Programmatic audio sync, charts that animate from data, or embedding shaders/Three.js into video.
## Core techniques
### Frame-driven animation
Animation is derived from the current frame, never from `setState` or `requestAnimationFrame`. `interpolate` maps an input range to an output range; `spring` produces physically natural motion.
```jsx
import {useCurrentFrame, useVideoConfig, interpolate, spring} from 'remotion';
export const Title = () => {
const frame = useCurrentFrame();
const {fps} = useVideoConfig();
// Fade in over frames 0-30, then stay (clamp prevents over/undershoot).
const opacity = interpolate(frame, [0, 30], [0, 1], {
extrapolateLeft: 'clamp',
extrapolateRight: 'clamp',
});
// Spring entrance; divide by spring duration is unnecessary — drive transforms directly.
const scale = spring({frame, fps, config: {damping: 200, mass: 1, stiffness: 100}});
return
Hello
;
};
```
Always clamp `interpolate` unless an intentional overshoot is desired — by default it extrapolates linearly past the range, which produces opacity > 1 or negative values.
### Scheduling: Sequence and Series
`` shifts time: children see `frame` reset to 0 at the sequence's `from`. Use it to place clips on a timeline. `` lays out back-to-back segments without manual offset math.
```jsx
import {Sequence, Series, AbsoluteFill} from 'remotion';
export const Timeline = () => (
{/* Series auto-sequences; offset overlaps the previous segment for crossfades */}
);
```
### Composition registration + parametric props
The `` declares id, size, fps, duration, and `defaultProps`. A zod schema makes props type-safe and editable in the Studio sidebar.
```jsx
import {Composition} from 'remotion';
import {z} from 'zod';
export const schema = z.object({
title: z.string(),
accent: z.string(),
fps: z.number().default(30),
});
export const Root = () => (
);
```
To make duration data-dependent, use `calculateMetadata` on the Composition to compute `durationInFrames` from props (e.g. number of rows × frames per row) before render.
### Audio and beat sync
```jsx
import {Audio, staticFile, useCurrentFrame, useVideoConfig} from 'remotion';
const BEATS_SEC = [0.5, 1.0, 1.5, 2.0]; // detected offline
export const Music = ({children}) => {
const frame = useCurrentFrame();
const {fps} = useVideoConfig();
const t = frame / fps;
const onBeat = BEATS_SEC.some((b) => Math.abs(t - b) < 1 / fps);
return (
<>
{children}
);
};
```
Detect beats offline (e.g. with `web-audio-beat-detector` or aubio) and bake the timestamps into props — never analyze audio at render time, since headless rendering has no realtime audio clock.
### Rendering
Preview in the browser-based Studio; render headlessly via CLI or the programmatic API.
```bash
npx remotion studio # interactive preview
npx remotion render Promo out/promo.mp4 \
--props='{"title":"Launch","accent":"#f43"}' # pass parametric props
npx remotion render Promo out.gif --codec=gif # GIF output
```
For batch/data-driven pipelines, render in Node with `@remotion/renderer` (bundle once, render many) — see the reference file.
## Deliver & verify (rendered stills → MP4)
> **Packaged helper** (`scripts/`): tile your stills with `scripts/contact-sheet.sh sheet.png f-hook.png f-mid.png f-end.png`, then assert the encode with `scripts/probe-mp4.sh out.mp4 [WxH] [fps]`. See `scripts/README.md`.
Remotion is frame-deterministic by construction — every frame is a pure function of `useCurrentFrame()`, so you can render any exact frame headlessly with **no seek harness** (this is the heavy-tier counterpart to a web scene's `?t=N`). Use this tier when the output must be an MP4/GIF, must carry exact numbers/text, or batches from data; for a lightweight web animation, deliver standalone HTML instead.
**Output contract:**
- A Remotion project with the composition registered (`` + zod `schema` + `defaultProps`), all motion frame-driven (no timers / `Date.now()` / `Math.random()`).
- Deliverable = the rendered `out/*.mp4` (plus the project, so the user can re-render with new props/data).
- Duration data-dependent? compute it in `calculateMetadata`, not by hand.
**Verify loop — render stills → inspect → encode.** Render single frames first (cheap, no video encode), inspect them, and encode the full video only once the frames are right.
```bash
# 1. Frame-exact stills at start / mid / end (PNG, headless, fast)
npx remotion still Promo out/f-start.png --frame=0
npx remotion still Promo out/f-mid.png --frame=75
npx remotion still Promo out/f-end.png --frame=149 # last frame = durationInFrames - 1
# render with the SAME props you'll ship, not just defaultProps:
# npx remotion still Promo out/f-mid.png --frame=75 --props='{"title":"Launch"}'
# 2. Inspect each PNG — fidelity (matches brief; numbers/text correct) AND
# artifacts (text overflow, off-canvas, clipped safe-area, missing font, wrong data binding).
# 3. Only after the stills check out, encode the video:
npx remotion render Promo out/promo.mp4 --props='{"title":"Launch"}'
```
- Use `npx remotion compositions` to read each composition's `durationInFrames`/`fps` and pick the end frame.
- **Data-driven / batch**: verify ONE representative props set via stills *before* batch-rendering all rows — catch a layout bug once instead of N times.
- **README demo GIF for free**: `npx remotion render Promo out/demo.gif --codec=gif` produces the first-screen proof clip (Direction D).
**Before you finish:**
1. `npx remotion still` renders cleanly at frame 0, mid, and last — no errors, no missing assets/fonts.
2. Numbers/text are exact and inside safe areas at every checked frame.
3. Frame-driven only — no `Date.now()` / `Math.random()` / timers (determinism holds in CI).
4. Props are zod-typed; the **shipped** props render correctly (not just `defaultProps`).
5. Full MP4 encoded and plays; (optional) GIF rendered for the README.
## Quick reference
| Need | Use |
|---|---|
| Map time → value | `interpolate(frame, [a,b], [x,y], {extrapolateRight:'clamp'})` |
| Natural easing | `spring({frame, fps, config})` |
| Place a clip at t | `` |
| Back-to-back shots | `` |
| Audio | `` |
| Frame ↔ seconds | `frame / fps` |
| Loop a value | `frame % period` then interpolate |
| Editable props | zod `schema` on `` |
| CI render | `npx remotion render` or `@remotion/renderer` |
## Gotchas
- Never use `Math.random()`, `Date.now()`, or animation timers — they break determinism. Use `random(seed)` from Remotion for stable per-frame randomness.
- Load fonts and assets via `staticFile()` and wait with `delayRender`/`continueRender`, or fonts pop in mid-render.
- Default `interpolate` extrapolates — clamp it.
- `useCurrentFrame` inside a `` is local (starts at 0); use `useVideoConfig().durationInFrames` for absolute timing.
## Reference files
- `references/api-and-patterns.md` — `interpolate` options and `Easing`, spring config recipes, Sequence/Series scheduling, `