Remotion

[IMPORTANT] Use TaskCreate to break ALL work into small tasks BEFORE starting. For simple tasks, ask user whether to skip. MUST ATTENTION wait for user approval of scene plan (Step 3.3) before writing any files — NEVER skip. MUST ATTENTION read existing project files before modifying — NEVER overwrite scenes blindly. MUST ATTENTION update totalChapters in ALL existing scene files when adding/removing scenes.

Be skeptical. Apply critical thinking. Every claim needs traced proof, confidence >80% to act.

Quick Summary

Goal: Create new Remotion video project, add/update scenes in existing one, or launch local Remotion Studio preview server.

Two Modes:

Default project path: remotion/ (relative to workspace root). Respect any path user explicitly provides.

Key Rules:

• NEVER implement scenes before user approves the plan (Step 3.3)
• Always read existing project structure before adding/modifying scenes
• Keep totalChapters consistent across ALL scene files
• All animations MUST be driven by useCurrentFrame() — CSS transitions FORBIDDEN
• Always use Remotion components (<Img>, <Video>, <Audio>) instead of native HTML elements

Implementing one of these? Copy from refs/ — do NOT implement from memory:

Phase 0: Mode Detection

Classify prompt:

PLAY keywords   → "play", "preview", "open studio", "start server", "watch", "launch", "dev server"
CREATE/UPDATE   → everything else (default)

Ambiguous → proceed with Create/Update (safe default).

Phase 1A: Detect Existing Project

Locate Remotion project before acting:

# Check default path
ls remotion/package.json 2>/dev/null

# Check if CWD is already a Remotion project
ls package.json 2>/dev/null | xargs grep -l '"remotion"' 2>/dev/null

# Check common paths
find . -maxdepth 3 -name "package.json" -exec grep -l '"remotion"' {} \; 2>/dev/null | head -5

State after detection:

• PROJECT_EXISTS = true/false
• PROJECT_PATH = remotion/ (default) or detected path
• HAS_STUDIO_SCRIPT = true/false (check package.json scripts.studio)

Phase 2: PLAY Mode

When: User explicitly asks to preview / open studio / launch dev server.

Step 2.1 — Verify project exists

If PROJECT_EXISTS = false:

"No Remotion project found. Run /remotion <description> to create one first." Exit.

Step 2.2 — Find launch command

cat {PROJECT_PATH}/package.json | grep '"studio"'
# → use: npm run studio
# → fallback: npx remotion studio

Step 2.3 — Start dev server (background)

cd {PROJECT_PATH} && npm run studio

Remotion Studio launches at http://localhost:3000

Server runs in background. Report URL and composition IDs visible in {source-root}/Root.tsx.

Step 2.4 — Optional: one-frame render check

npx remotion still [composition-id] --scale=0.25 --frame=30
# At 30fps, --frame=30 = one-second mark (zero-based)

Phase 3: CREATE / UPDATE Mode

Step 3.1 — New vs Update Decision

Step 3.2 — Scaffold New Project

Only when no existing Remotion project found.

3.2.1 Bootstrap with create-video (preferred)

# Creates {PROJECT_PATH}/ with blank template (no Tailwind)
npx create-video@latest --yes --blank --no-tailwind {PROJECT_PATH}
cd {PROJECT_PATH}
npm install @remotion/transitions  # add transitions support

Replace generated {source-root}/ with project structure below (keep package.json and tsconfig.json from scaffold).

Fallback (manual) — when npx create-video unavailable

mkdir -p {PROJECT_PATH}/{source-root}/compositions {PROJECT_PATH}/{source-root}/components {PROJECT_PATH}/{source-root}/utils
cd {PROJECT_PATH}
npm init -y
npm install remotion @remotion/cli @remotion/transitions react react-dom
npm install -D @types/react @types/react-dom typescript

Directory structure (both paths)

{PROJECT_PATH}/
  package.json          ← scripts: studio, render, still
  tsconfig.json
  {source-root}/
    index.ts            ← registerRoot
    Root.tsx            ← register compositions
    components/
      Shared.tsx        ← palette + reusable UI components
    utils/
      animations.ts     ← easeOut, staggeredEaseOut, pop, counter
    compositions/
      {CompositionName}.tsx

3.2.3 Create package.json scripts (merge into existing after install)

{
    "scripts": {
        "studio": "remotion studio",
        "render": "remotion render {CompositionId} out/video.mp4",
        "still": "remotion still {CompositionId} --frame=0 out/still.png"
    },
    "remotion": {
        "entryPoint": "{source-root}/index.ts"
    }
}

3.2.4 Create tsconfig.json

{
    "compilerOptions": {
        "target": "ES2020",
        "lib": ["dom", "ES2020"],
        "jsx": "react-jsx",
        "module": "commonjs",
        "moduleResolution": "node",
        "strict": true,
        "esModuleInterop": true,
        "skipLibCheck": true,
        "outDir": "dist"
    },
    "include": ["src"]
}

3.2.5 Create {source-root}/index.ts

import { registerRoot } from 'remotion';
import { Root } from './Root';
registerRoot(Root);

3.2.6 Create {source-root}/components/Shared.tsx

Copy from refs/Shared.tsx — do NOT implement from memory. Exports: C (palette), ProgressBar, ChapterBadge, CodeBlock, Pill, AnimRow. Always create; all scenes import from here.

3.2.7 Create {source-root}/utils/animations.ts

Copy from refs/animations.ts — do NOT implement from memory. Exports: easeOut, easeInOut, pop, staggeredEaseOut, counter.

Step 3.3 — Plan Composition Structure

MUST ATTENTION wait for user confirmation before implementing any scenes.

Plan composition before writing files:

1. Parse intent — What video about? What information to convey?
2. Decide scene count — 1 scene per major concept (30s → ~4 scenes, 60s → ~8, 90s → ~12)
3. Assign durations — Each scene: 6–12s (180–360 frames @ 30fps)
4. Name scenes — Scene01Intro, Scene02{Topic}, etc.
5. Write scene brief — what shown, key data, visual layout (left/right split, full-width, grid)

Present plan before writing files:

Proposed: {N} scenes, ~{total}s total
  Scene 01 ({Xs}) — {topic}: {layout description}
  Scene 02 ({Xs}) — {topic}: {layout description}
  …
Proceed? (or adjust)

Step 3.4 — Read Existing Project (UPDATE path)

MUST ATTENTION read existing project state before any modifications.

When PROJECT_EXISTS = true:

# Read composition registry
cat {PROJECT_PATH}/{source-root}/Root.tsx

# List scene files
ls {PROJECT_PATH}/{source-root}/compositions/ 2>/dev/null || ls {PROJECT_PATH}/{source-root}/scenes/ 2>/dev/null

# Read main composition orchestrator
cat {PROJECT_PATH}/{source-root}/ClaudeAgentExplainer.tsx 2>/dev/null  # or equivalent

Identify:

• Existing scene count and names
• Current totalChapters / composition duration
• Where to insert / which scenes to modify

Target only scenes affected by user's request. Preserve all unchanged scenes.

Step 3.5 — Implement Scene Files

Scene file anatomy (follow exactly)

import { AbsoluteFill, useCurrentFrame, interpolate } from 'remotion';
import { C, ProgressBar, ChapterBadge } from '../components/Shared';  // adjust path
import { easeOut, staggeredEaseOut } from '../utils/animations';       // adjust path

// Data arrays at the top — keep out of component body
const ITEMS = [ ... ];

export const Scene{NN}{Name}: React.FC = () => {
    const frame = useCurrentFrame();

    return (
        <AbsoluteFill style={{ background: C.bg, fontFamily: 'system-ui, -apple-system, sans-serif' }}>
            <ChapterBadge index={NN} label="{Scene Name}" color={C.blue} />

            <div style={{ position: 'absolute', inset: 0, display: 'flex', gap: 48, padding: '68px 72px 44px' }}>
                {/* Content here */}
            </div>

            <ProgressBar chapterIndex={NN - 1} totalChapters={TOTAL} />
        </AbsoluteFill>
    );
};

Animation rules

Layout patterns

Left/Right split (most common):

<div style={{ position: 'absolute', inset: 0, display: 'flex', gap: 48, padding: '68px 72px 44px' }}>
    <div style={{ width: 400, flexShrink: 0, ... }}>  {/* Left panel */}
    <div style={{ flex: 1, ... }}>                     {/* Right panel */}
</div>

Full-width column:

<div style={{ position: 'absolute', inset: 0, display: 'flex', flexDirection: 'column', padding: '68px 64px 44px', gap: 16 }}>

Centered (title/CTA scene):

<div style={{ position: 'absolute', inset: 0, display: 'flex', flexDirection: 'column', justifyContent: 'center', alignItems: 'center', padding: '72px 100px', textAlign: 'center' }}>

Card grid:

<div style={{ display: 'grid', gridTemplateColumns: 'repeat(4, 1fr)', gap: 12 }}>

Color and font guidelines

Step 3.6 — Wire Root.tsx

Multi-scene composition (with transitions)

import { TransitionSeries, linearTiming } from '@remotion/transitions';
import { fade } from '@remotion/transitions/fade';
import { Scene01Intro } from './compositions/Scene01Intro';
// ... other imports

const T = 18; // transition duration in frames

const D = {
    s01: 210, // 7s
    s02: 240 // 8s
    // ...
};

const SCENES = Object.values(D).length;
export const TOTAL_DURATION_FRAMES = Object.values(D).reduce((a, b) => a + b, 0) - (SCENES - 1) * T;

const tr = () => <TransitionSeries.Transition presentation={fade()} timing={linearTiming({ durationInFrames: T })} />;

export const {
    CompositionName
}: React.FC = () => (
    <TransitionSeries>
        <TransitionSeries.Sequence durationInFrames={D.s01}>
            <Scene01Intro />
        </TransitionSeries.Sequence>
        {tr()}
        <TransitionSeries.Sequence durationInFrames={D.s02}>
            <Scene02Next />
        </TransitionSeries.Sequence>
        {/* ... */}
    </TransitionSeries>
);

// Root.tsx
import { Composition } from 'remotion';
import { {CompositionName}, TOTAL_DURATION_FRAMES } from './{CompositionName}';

export const Root: React.FC = () => (
    <Composition id="{CompositionId}" component={{{CompositionName}}} durationInFrames={TOTAL_DURATION_FRAMES} fps={30} width={1920} height={1080} />
);

Single-scene composition

// Root.tsx
import { Composition } from 'remotion';
import { MyScene } from './compositions/MyScene';

export const Root: React.FC = () => <Composition id="MyVideo" component={MyScene} durationInFrames={300} fps={30} width={1920} height={1080} />;

Step 3.7 — Post-scaffold: launch prompt

After creating/updating, report changed files and offer launch:

✅ Created {N} scene files in {PROJECT_PATH}/{source-root}/compositions/
   Total duration: ~{X}s ({FRAMES} frames @ 30fps)

To preview: run `/remotion play` — starts Remotion Studio at http://localhost:3000
To render:  cd {PROJECT_PATH} && npm run render

Update Mode: Specific Scenarios

Add a new scene

1. Read Root.tsx to find composition orchestrator and current scene count
2. Read totalChapters across existing scenes
3. Determine insertion point (end = safest)
4. Create new scene file following anatomy above
5. Update Root / composition orchestrator:
   • Add import
   • Add D.sNN entry
   • Add <TransitionSeries.Sequence> block
   • MUST ATTENTION update totalChapters in ALL existing scene files (+1)

Modify an existing scene

1. Read specific scene file
2. Identify data array or JSX block needing change
3. Make surgical edits only — do not touch unrelated sections

Change visual style / palette

1. Edit {source-root}/components/Shared.tsx → C object
2. Font changes: update fontFamily in AbsoluteFill style per scene (or add global in Shared)

Remotion API Reference

Authoritative Remotion API reference — apply when implementing beyond basic scene creation.

Animations (Core Rules)

MUST ATTENTION ALL animations driven by useCurrentFrame(). Durations: seconds × fps.

import { useCurrentFrame, useVideoConfig, interpolate, Easing } from 'remotion';

export const FadeIn = () => {
    const frame = useCurrentFrame();
    const { fps } = useVideoConfig();
    const opacity = interpolate(frame, [0, 2 * fps], [0, 1], {
        extrapolateRight: 'clamp',
        extrapolateLeft: 'clamp',
        easing: Easing.bezier(0.16, 1, 0.3, 1)
    });
    return <div style={{ opacity }}>Hello World!</div>;
};

FORBIDDEN: CSS transition-*, CSS animation-*, Tailwind transition-*/animate-* classes.

Timing — interpolate & Bézier Easing

// With clamping + Bézier easing
const opacity = interpolate(frame, [0, 60], [0, 1], {
    easing: Easing.bezier(0.16, 1, 0.3, 1),
    extrapolateLeft: 'clamp',
    extrapolateRight: 'clamp'
});

Copy-paste curves:

easing: Easing.bezier(0.16, 1, 0.3, 1); // crisp UI entrance (strong ease-out)
easing: Easing.bezier(0.45, 0, 0.55, 1); // editorial / slow fade
easing: Easing.bezier(0.34, 1.56, 0.64, 1); // playful overshoot

Composing multiple properties from one progress:

const slideIn = interpolate(frame, [start, start + dur], [0, 1], {
    easing: Easing.bezier(0.22, 1, 0.36, 1),
    extrapolateLeft: 'clamp',
    extrapolateRight: 'clamp'
});
const overlayX = interpolate(slideIn, [0, 1], [100, 0]);
const opacity = interpolate(slideIn, [0, 1], [0, 1]);

Sequencing & Trimming

<Sequence> delays element appearance. useCurrentFrame() inside = local frame (0-based). Always premountFor:

<Sequence from={1 * fps} durationInFrames={2 * fps} premountFor={1 * fps}>
    <Title />
</Sequence>

<Series> for sequential without overlap:

<Series>
    <Series.Sequence durationInFrames={45}>
        <Intro />
    </Series.Sequence>
    <Series.Sequence durationInFrames={60}>
        <MainContent />
    </Series.Sequence>
    <Series.Sequence offset={-15} durationInFrames={60}>
        <SceneB />
    </Series.Sequence>{' '}
    {/* overlap */}
</Series>

Trimming:

<Sequence from={-0.5 * fps}><MyAnimation /></Sequence>       // skip first 15 frames
<Sequence durationInFrames={1.5 * fps}><MyAnimation /></Sequence>  // trim end
<Sequence from={30}><Sequence from={-15}><MyAnimation /></Sequence></Sequence>  // trim + delay

Compositions

import { Composition, Folder, Still } from "remotion";

<Composition id="MyComposition" component={MyComp} durationInFrames={100} fps={30} width={1080} height={1080} />

// With default props (use `type` not `interface`)
<Composition id="MyComposition" component={MyComp} durationInFrames={100} fps={30} width={1080} height={1080}
  defaultProps={{ title: "Hello World", color: "#ff0000" } satisfies MyCompositionProps}
/>

// Still (single-frame)
<Still id="Thumbnail" component={Thumbnail} width={1280} height={720} />

Assets — staticFile() & public folder

MUST use staticFile() for assets in public/:

import { Img, staticFile } from "remotion";
import { Video } from "@remotion/media";
import { Audio } from "@remotion/media";

<Img src={staticFile("logo.png")} />
<Video src={staticFile("clip.mp4")} />
<Audio src={staticFile("music.mp3")} />
// Remote URLs work directly — no staticFile needed

Images

MUST use <Img> from remotion — NOT <img>, NOT Next.js <Image>, NOT CSS background-image.

import { Img, staticFile } from "remotion";

<Img src={staticFile("photo.png")} style={{ width: 500, height: 300, objectFit: "cover" }} />
<Img src={staticFile(`frames/frame${frame}.png`)} />  // dynamic paths work

Videos

Install: npx remotion add @remotion/media

import { Video } from "@remotion/media";

<Video src={staticFile("video.mp4")} />
<Video src={staticFile("video.mp4")} trimBefore={2 * fps} trimAfter={10 * fps} />
<Video src={staticFile("video.mp4")} volume={(f) => interpolate(f, [0, fps], [0, 1], { extrapolateRight: "clamp" })} />
<Video src={staticFile("video.mp4")} playbackRate={2} loop muted />

Audio

Install: npx remotion add @remotion/media

import { Audio } from "@remotion/media";

<Audio src={staticFile("audio.mp3")} />
<Audio src={staticFile("audio.mp3")} trimBefore={2 * fps} trimAfter={10 * fps} />
<Sequence from={1 * fps}><Audio src={staticFile("audio.mp3")} /></Sequence>  // delay
// volume callback: `f` starts at 0 when audio begins, not composition frame
<Audio src={staticFile("audio.mp3")} volume={(f) => interpolate(f, [0, fps], [0, 1], { extrapolateRight: "clamp" })} />

GIFs & Animated Images

import { AnimatedImage, staticFile } from "remotion";

// Preferred: supports GIF, APNG, AVIF, WebP
<AnimatedImage src={staticFile("animation.gif")} width={500} height={500} />
<AnimatedImage src={staticFile("animation.gif")} width={500} height={300} fit="cover" playbackRate={2} />

// Fallback: GIF only — npx remotion add @remotion/gif
import { Gif } from "@remotion/gif";
<Gif src={staticFile("animation.gif")} width={500} height={500} />

Fonts

Google Fonts (recommended): npx remotion add @remotion/google-fonts

import { loadFont } from '@remotion/google-fonts/Roboto';

const { fontFamily } = loadFont('normal', { weights: ['400', '700'], subsets: ['latin'] });
<h1 style={{ fontFamily, fontSize: 80, fontWeight: 'bold' }}>{text}</h1>;

Local fonts: npx remotion add @remotion/fonts

import { loadFont } from '@remotion/fonts';
import { staticFile } from 'remotion';

await Promise.all([
    loadFont({ family: 'Inter', url: staticFile('Inter-Regular.woff2'), weight: '400' }),
    loadFont({ family: 'Inter', url: staticFile('Inter-Bold.woff2'), weight: '700' })
]);

Transitions (Full API)

npx remotion add @remotion/transitions

import { TransitionSeries, linearTiming, springTiming } from "@remotion/transitions";
import { fade } from "@remotion/transitions/fade";
import { slide } from "@remotion/transitions/slide";
import { wipe } from "@remotion/transitions/wipe";
import { flip } from "@remotion/transitions/flip";

<TransitionSeries>
  <TransitionSeries.Sequence durationInFrames={60}><SceneA /></TransitionSeries.Sequence>
  <TransitionSeries.Transition presentation={fade()} timing={linearTiming({ durationInFrames: 15 })} />
  <TransitionSeries.Sequence durationInFrames={60}><SceneB /></TransitionSeries.Sequence>
</TransitionSeries>

// Slide directions: "from-left" | "from-right" | "from-top" | "from-bottom"
<TransitionSeries.Transition presentation={slide({ direction: "from-left" })} timing={linearTiming({ durationInFrames: 20 })} />

// Spring timing
springTiming({ config: { damping: 200 }, durationInFrames: 25 })

// Overlay (no duration shortening — note: cannot be adjacent to transition or another overlay)
<TransitionSeries.Overlay durationInFrames={20} offset={0}><MyEffect /></TransitionSeries.Overlay>

Duration: two 60-frame scenes + 15-frame transition = 60 + 60 - 15 = 105 frames total.

Light Leaks (Overlay Effect)

Requires Remotion ≥ 4.0.415. Check: npx remotion versions. Upgrade: npx remotion upgrade.

npx remotion add @remotion/light-leaks

import { LightLeak } from "@remotion/light-leaks";

// As TransitionSeries overlay
<TransitionSeries.Overlay durationInFrames={30}><LightLeak /></TransitionSeries.Overlay>

// Standalone decorative overlay
<AbsoluteFill>
  <MyContent />
  <LightLeak durationInFrames={60} seed={3} />
</AbsoluteFill>

// seed: different patterns; hueShift: 0=yellow-orange, 120=green, 240=blue
<LightLeak seed={5} hueShift={240} />

3D with Three.js (React Three Fiber)

npx remotion add @remotion/three

MUST wrap in <ThreeCanvas> with width and height props. FORBIDDEN: useFrame() from @react-three/fiber — causes flickering. Use useCurrentFrame().

import { ThreeCanvas } from '@remotion/three';
import { useVideoConfig, useCurrentFrame } from 'remotion';

const { width, height } = useVideoConfig();
const frame = useCurrentFrame();

<ThreeCanvas width={width} height={height}>
    <ambientLight intensity={0.4} />
    <directionalLight position={[5, 5, 5]} intensity={0.8} />
    <mesh rotation={[0, frame * 0.02, 0]}>
        <boxGeometry args={[2, 2, 2]} />
        <meshStandardMaterial color="#4a9eff" />
    </mesh>
</ThreeCanvas>;

// <Sequence> inside ThreeCanvas must use layout="none"

Text Animations

All text animations driven by useCurrentFrame(). CSS transitions FORBIDDEN.

Typewriter — use string slicing, NEVER per-character opacity. Spring word highlight — scaleX wipe from left.

Implementing typewriter or word-highlight? Copy from refs/text-animations.tsx — do NOT implement from memory. Contains: getTypedText, Cursor, TypewriterScene, Highlight.

Text Measurement

npx remotion add @remotion/layout-utils

import { measureText, fitText, fillTextBox } from '@remotion/layout-utils';

const { width, height } = measureText({ text: 'Hello World', fontFamily: 'Arial', fontSize: 32, fontWeight: 'bold' });
const { fontSize } = fitText({ text: 'Hello World', withinWidth: 600, fontFamily: 'Inter', fontWeight: 'bold' });

MUST ATTENTION call only after fonts loaded. Use validateFontIsLoaded: true. Match font properties exactly between measurement and rendering.

DOM Node Measurement

Remotion applies scale() transform — use useCurrentScale() to get true dimensions:

import { useCurrentScale } from 'remotion';

const scale = useCurrentScale();
const rect = ref.current.getBoundingClientRect();
const trueWidth = rect.width / scale;

Captions & Subtitles

npx remotion add @remotion/captions

Caption type: { text, startMs, endMs, timestampMs, confidence }

Transcribe with Whisper.cpp: npx remotion add @remotion/install-whisper-cpp

import { installWhisperCpp, downloadWhisperModel, transcribe, toCaptions } from '@remotion/install-whisper-cpp';

await installWhisperCpp({ to: './whisper.cpp', version: '1.5.5' });
await downloadWhisperModel({ model: 'medium.en', folder: './whisper.cpp' });
// Convert to 16KHz wav first: npx remotion ffmpeg -i input.mp4 -ar 16000 output.wav
const whisperOutput = await transcribe({
    model: 'medium.en',
    whisperPath: './whisper.cpp',
    whisperCppVersion: '1.5.5',
    inputPath: '/path/to/audio.wav',
    tokenLevelTimestamps: true
});
const { captions } = toCaptions({ whisperCppOutput: whisperOutput });

Import from.srt:

import { parseSrt } from '@remotion/captions';
const { captions } = parseSrt({ input: await fetch(staticFile('subtitles.srt')).then(r => r.text()) });

TikTok-style word highlight display:

Implementing TikTok-style captions? Copy from refs/captions.tsx — do NOT implement from memory. Contains: CaptionedVideo, CaptionPage, delayRender, createTikTokStyleCaptions, per-token active highlighting.

Note: use whiteSpace: "pre" — captions are whitespace-sensitive.

Dynamic Compositions — calculateMetadata

import { CalculateMetadataFunction } from 'remotion';

const calculateMetadata: CalculateMetadataFunction<Props> = async ({ props, abortSignal }) => {
    const durationInSeconds = await getVideoDuration(props.videoSrc);
    return { durationInFrames: Math.ceil(durationInSeconds * 30) };
};

// Transform props (fetch data before render)
const calculateMetadata: CalculateMetadataFunction<Props> = async ({ props, abortSignal }) => {
    const data = await fetch(props.dataUrl, { signal: abortSignal }).then(r => r.json());
    return { props: { ...props, fetchedData: data } };
};

// Return values (all optional): durationInFrames, width, height, fps, props, defaultOutName, defaultCodec

Parameters — Zod Schema

import { z } from 'zod';
import { zColor } from '@remotion/zod-types';

export const MyCompositionSchema = z.object({
    title: z.string(),
    color: zColor() // renders color picker in Studio
});

// Root.tsx
<Composition
    id="MyComposition"
    component={MyComponent}
    schema={MyCompositionSchema}
    durationInFrames={100}
    fps={30}
    width={1080}
    height={1080}
    defaultProps={{ title: 'Hello World', color: '#ff0000' }}
/>;

Top-level type MUST be z.object().

Mediabunny — Video/Audio Metadata

npx remotion add mediabunny

Need video/audio duration, dimensions, or frame extraction? Copy from refs/mediabunny-utils.ts — do NOT implement from memory. Contains: getVideoDuration, getAudioDuration, getVideoDimensions, canDecode, extractFrames.

Use staticFile() for local files. Use FileSource instead of UrlSource in Node.js/Bun.

FFmpeg in Remotion

npx remotion ffmpeg -i input.mp4 output.mp3
npx remotion ffprobe input.mp4

Trimming — prefer <Video> props (non-destructive, no re-encoding):

<Video src={staticFile('video.mp4')} trimBefore={5 * fps} trimAfter={10 * fps} />

// FFmpeg fallback (MUST re-encode to avoid frozen frames)
// npx remotion ffmpeg -ss 00:00:05 -i public/input.mp4 -to 00:00:10 -c:v libx264 -c:a aac public/output.mp4

Silence Detection

# Step 1: measure loudness
npx remotion ffmpeg -i public/video.mov -map 0:a -af loudnorm=print_format=json -f null /dev/null
# → read input_i (integrated loudness dB) and input_thresh

# Step 2: detect silences (d=0.5 = min silence duration in seconds)
npx remotion ffmpeg -i public/video.mov -map 0:a -af "silencedetect=noise=${THRESH}dB:d=0.5" -f null /dev/null

<Video src={staticFile('video.mov')} trimBefore={Math.floor(leadingEnd * fps)} trimAfter={Math.ceil(trailingStart * fps)} />

Audio Visualization

npx remotion add @remotion/media-utils

import { useWindowedAudioData, visualizeAudio, visualizeAudioWaveform, createSmoothSvgPath } from '@remotion/media-utils';

const { audioData, dataOffsetInSeconds } = useWindowedAudioData({ src: staticFile('music.mp3'), frame, fps, windowInSeconds: 30 });
if (!audioData) return null;

// Spectrum bars (numberOfSamples must be power of 2)
const frequencies = visualizeAudio({ fps, frame, audioData, numberOfSamples: 256, optimizeFor: 'speed', dataOffsetInSeconds });
// Values 0-1; left=bass, right=highs

// Waveform SVG
const waveform = visualizeAudioWaveform({ fps, frame, audioData, numberOfSamples: 256, windowInSeconds: 0.5, dataOffsetInSeconds });
const path = createSmoothSvgPath({ points: waveform.map((y, i) => ({ x: (i / (waveform.length - 1)) * width, y: 100 + y * 100 })) });

// Bass-reactive scale
const bassIntensity = frequencies.slice(0, 32).reduce((sum, v) => sum + v, 0) / 32;
const scale = 1 + bassIntensity * 0.5;

MUST ATTENTION pass frame from parent to child visualization — NEVER call useCurrentFrame() in each child inside <Sequence>.

Logarithmic scaling: const db = 20 * Math.log10(value); const scaled = (db - (-100)) / ((-30) - (-100));

Lottie Animations

npx remotion add @remotion/lottie

import { Lottie, LottieAnimationData } from '@remotion/lottie';
import { cancelRender, continueRender, delayRender } from 'remotion';

export const MyAnimation = () => {
    const [handle] = useState(() => delayRender('Loading Lottie animation'));
    const [animationData, setAnimationData] = useState<LottieAnimationData | null>(null);

    useEffect(() => {
        fetch('https://assets4.lottiefiles.com/packages/lf20_zyquagfl.json')
            .then(r => r.json())
            .then(json => {
                setAnimationData(json);
                continueRender(handle);
            })
            .catch(err => {
                cancelRender(err);
            });
    }, [handle]);

    if (!animationData) return null;
    return <Lottie animationData={animationData} style={{ width: 400, height: 400 }} />;
};

Charts & Data Visualization

MUST ATTENTION drive all animations from useCurrentFrame(). Disable all third-party chart library animations.

import { spring, evolvePath, getLength, getPointAtLength, getTangentAtLength } from '@remotion/paths';

// Bar chart — spring stagger
const bars = data.map((item, i) => {
    const height = spring({ frame, fps, delay: i * 5, config: { damping: 200 } });
    return <div style={{ height: height * item.value }} />;
});

// Line chart path animation (npx remotion add @remotion/paths)
const pathProgress = interpolate(frame, [0, 2 * fps], [0, 1], { extrapolateLeft: 'clamp', extrapolateRight: 'clamp' });
const { strokeDasharray, strokeDashoffset } = evolvePath(pathProgress, svgPath);
<path d={svgPath} fill="none" stroke="#FF3232" strokeWidth={4} strokeDasharray={strokeDasharray} strokeDashoffset={strokeDashoffset} />;

Maps with Mapbox

npm i mapbox-gl @turf/turf @types/mapbox-gl — set REMOTION_MAPBOX_TOKEN in .env.

Implementing Mapbox map scene? Copy from refs/maps-mapbox.tsx — do NOT implement from memory. Key rules: interactive: false, fadeDuration: 0, explicit width/height/position: "absolute" on container, animate camera via useCurrentFrame(), NO cleanup (_map.remove()). Render: npx remotion render --gl=angle --concurrency=1.

Transparent Video Rendering

# ProRes (for video editors)
npx remotion render --image-format=png --pixel-format=yuva444p10le --codec=prores --prores-profile=4444 MyComp out.mov

# WebM VP9 (for browsers)
npx remotion render --image-format=png --pixel-format=yuva420p --codec=vp9 MyComp out.webm

AI Voiceover (ElevenLabs TTS)

Implementing ElevenLabs TTS voiceover? Copy from refs/generate-voiceover.ts — do NOT implement from memory. Includes calculateMetadata integration to size composition to audio duration.

Sound Effects

import { Audio } from '@remotion/sfx';
<Audio src={'https://remotion.media/whoosh.wav'} />;

Available: whoosh, whip, page-turn, switch, mouse-click, shutter-modern, shutter-old, ding, bruh, vine-boom, windows-xp-error — all at https://remotion.media/{name}.wav

TailwindCSS

Use if installed. NEVER use transition-* or animate-* Tailwind classes — animate via useCurrentFrame().

Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.

AI Mistake Prevention — Failure modes to avoid on every task:

Re-read files after context changes. Context compaction, resume, or long-running work can make memory stale; verify current files before acting. Verify generated content against source evidence. AI hallucinates APIs, names, claims, and document facts. Check the relevant source before documenting or referencing. Check downstream references before deleting or renaming. Removing an artifact can stale docs, generated mirrors, configs, and callers; map references first. Trace the full impact chain after edits. Changing a definition can miss derived outputs and consumers. Follow the affected chain before declaring done. Verify ALL affected outputs, not just the first. One green check is not all green checks; validate every output surface the change can affect. Assume existing values are intentional — ask WHY before changing OR flagging one as a defect. Before changing or reporting a constant, limit, flag, cutoff, wording, or pattern, read nearby context and history, the CALLER's ordering, and 2+ sibling call sites of the same convention. A doc stating WHAT without WHY is missing rationale, not proof of a missing guard. Surface ambiguity before acting — don't pick silently. Multiple valid interpretations require an explicit question or stated assumption with risk. Assert the outcome your system owns, not the intermediate state your infrastructure owns. When verifying async work, assert the final business state — never the delivery/retry bookkeeping held in shared infrastructure that any co-running process can write. Such a check passes when run alone and flakes the moment anything else shares that infrastructure. Keep shared guidance role-relevant. Universal guidance must help every receiving skill or agent; code-specific obligations belong only in code-specific protocols.

Project Protocol Overlay — Before executing this skill, resolve any PROJECT overlay rules layered onto it: match this skill's name against the Target column of the project's skill-protocol index (docs/project-reference/skill-protocols-reference.md by default; a referenceDocs entry in docs/project-config.json overrides the path), taking the most specific matching tier ONLY — exact name > glob > *. That precedence orders overlays against EACH OTHER, never against this skill. Read ONLY the matched bodies, resolved as <protocols-dir>/<Name>.md; a row's Body link is display text, never a read path. A matched body that is missing or malformed is REPORTED and skipped — never reconstructed from the index Description. No index, or no match -> proceed with no overlay, silently. Full contract: .claude/skills/project-skill-protocol/references/registry.md.

Overlays are ADDITIVE ONLY: they ADD rules on top of this skill's own protocol and NEVER replace, override, disable, or reinterpret a rule it already states — removing every overlay must return this skill to exactly its documented behavior. An overlay is a BRIEF, not an authority escalation: it can NEVER waive a workflow gate, git discipline, a review gate, or a user-confirmation gate. A genuine overlay-vs-skill conflict, or two equally-specific overlays that directly contradict -> surface both to the user; NEVER resolve silently.

MUST ATTENTION resolve project protocol overlays for this skill BEFORE executing — most specific matching tier only (exact > glob > *, which ranks overlays against each other, NEVER against this skill), read only matched bodies at <protocols-dir>/<Name>.md; a missing or malformed body is reported, never reconstructed. Overlays are ADDITIVE ONLY (they never replace this skill's own rules) and are a brief, NEVER an authority escalation; an equal-specificity contradiction goes to the user.

Closing Reminders

Protocols in force (concise digest of the SYNC/shared blocks this skill carries):

• Critical Thinking: MUST ATTENTION apply critical + sequential thinking; every claim needs traced proof, confidence >80% to act.

• AI Mistake Prevention: verify generated content against evidence, trace downstream references, verify all affected outputs, re-read after context loss, surface ambiguity.

• MUST ATTENTION wait for user approval of scene plan (Step 3.3) — NEVER implement scenes before approval

• MUST ATTENTION read existing project structure (Step 3.4) before modifications — NEVER overwrite blindly

• MUST ATTENTION update totalChapters in ALL scene files when adding/removing scenes — one missed file causes visual regression

• MUST ATTENTION keep data arrays outside component body — NEVER define `c

…(truncated)