ElevenLabs Voiceover Generation

Generate professional AI voiceovers for Remotion videos using ElevenLabs API.

Prerequisites

• ELEVENLABS_API_KEY in .env.local

Quick Start

# Generate voiceover from text
node .claude/skills/elevenlabs-remotion-skill/generate.js --text "Your text here" --output public/audio/voiceover.mp3

# Generate with narrator style (more natural)
node .claude/skills/elevenlabs-remotion-skill/generate.js --text "Your text" --character narrator --output voiceover.mp3

# Generate scenes with request stitching
node .claude/skills/elevenlabs-remotion-skill/generate.js --scenes remotion/scenes.json --output-dir public/audio/project/

# Regenerate a single scene
node .claude/skills/elevenlabs-remotion-skill/generate.js --scenes scenes.json --scene scene2 --new-text "Updated text"

# List available voices and character presets
node .claude/skills/elevenlabs-remotion-skill/generate.js --list-voices
node .claude/skills/elevenlabs-remotion-skill/generate.js --list-characters

Character Presets

Use character presets for more natural voiceovers instead of literal screen text reading:

# Use narrator style globally
node .claude/skills/elevenlabs-remotion-skill/generate.js --scenes scenes.json --character narrator --output-dir public/audio/

# Or set per-scene in scenes.json
{
  "scenes": [
    { "id": "scene1", "text": "Problem statement", "character": "dramatic" },
    { "id": "scene2", "text": "Solution", "character": "calm" }
  ]
}

Scene-Based Generation with Request Stitching

Generate multiple scenes with consistent prosody using ElevenLabs request stitching:

scenes.json Format

{
  "name": "product-demo",
  "voice": "George",
  "character": "narrator",
  "scenes": [
    {
      "id": "scene1",
      "text": "Generic text-to-speech sounds robotic. Your brand deserves better.",
      "duration": 4.5,
      "character": "dramatic"
    },
    {
      "id": "scene2",
      "text": "With voice cloning, you can use your own voice for unlimited content.",
      "duration": 5.5
    },
    {
      "id": "scene3",
      "text": "Record a short sample. Clone it. Create professional voiceovers in minutes.",
      "duration": 6,
      "delay": 0.3
    }
  ]
}

Generate All Scenes

node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/product-demo-scenes.json \
  --output-dir public/audio/product-demo/

This creates:

• product-demo-scene1.mp3 through sceneN.mp3
• product-demo-combined.mp3 (all scenes stitched)
• product-demo-info.json (metadata with durations)

Single Scene Regeneration

If a scene starts too early, has wrong timing, or needs different text:

# Regenerate scene2 with new text
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/scenes.json \
  --scene scene2 \
  --new-text "Updated scene 2 text" \
  --output-dir public/audio/project/

# Regenerate scene3 with different character
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/scenes.json \
  --scene scene3 \
  --character salesperson \
  --output-dir public/audio/project/

# Just regenerate (same text, same character)
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/scenes.json \
  --scene scene1 \
  --output-dir public/audio/project/

# Embed a thumbnail into an MP4 video
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --embed-thumbnail public/videos/my-video.mp4 \
  --thumbnail public/videos/my-thumbnail.png \
  --output public/videos/my-video-with-thumb.mp4

The tool automatically:

• Uses request stitching from previous scenes for consistent prosody
• Updates the info.json file with new metadata
• Updates scenes.json if --new-text is provided

Thumbnail Embedding

Embed a thumbnail image into MP4 videos so platforms like Twitter, YouTube, and video players display your custom thumbnail instead of the first frame.

Embed Thumbnail into Video

# Basic usage - outputs to video-thumb.mp4
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --embed-thumbnail public/videos/promo.mp4 \
  --thumbnail public/videos/thumbnail.png

# Custom output path
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --embed-thumbnail public/videos/promo.mp4 \
  --thumbnail public/videos/thumbnail.png \
  --output public/videos/promo-final.mp4

Workflow with Remotion

# 1. Render your video
npx remotion render MyVideo public/videos/my-video.mp4

# 2. Render your thumbnail (use Still composition)
npx remotion still MyVideoThumbnail public/videos/my-thumbnail.png

# 3. Embed the thumbnail
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --embed-thumbnail public/videos/my-video.mp4 \
  --thumbnail public/videos/my-thumbnail.png \
  --output public/videos/my-video-final.mp4

Supported Formats

• Video: MP4 (H.264/H.265)
• Thumbnail: PNG, JPG, JPEG

The embedding uses ffmpeg's -disposition:v:1 attached_pic flag to set the thumbnail as an attached picture, which most video players and platforms recognize.

Timing Validation

The skill automatically validates timing after generation using ffprobe:

What It Checks

Validate Existing Audio

# Validate all scenes in a project
node .claude/skills/elevenlabs-remotion-skill/generate.js --validate public/audio/product-demo/

Output example:

🔍 Validating product-demo (6 scenes)

❌ scene1: 3.00s (expected: 4.5s)
   ❌ Audio 1.50s shorter than expected
   👍 8 words @ 3.1 words/sec
⚠️ scene2: 6.35s (expected: 5.5s)
   ⚠️ Leading silence: 235ms (may start late)
   🐢 10 words @ 1.8 words/sec
✅ scene4: 4.36s (expected: 4s)
   👍 9 words @ 2.3 words/sec

📊 Total duration: 30.80s (expected: 30.00s)

Updated info.json

After validation, the info.json includes actual measurements:

{
  "scenes": [
    {
      "id": "scene1",
      "duration": 4.5,
      "actualDuration": 3.0,
      "leadingSilence": 0.05,
      "wordsPerSecond": 3.1
    }
  ]
}

Use actualDuration in your Remotion composition for precise sync.

Options

Recommended Voices

Integration with Remotion

After generating scene voiceovers, use them in your composition:

import { Audio, Sequence, staticFile } from "remotion";

// Use individual scene audio files for precise sync
const SCENE_DURATIONS = {
  scene1: 4.5,  // From info.json
  scene2: 5.5,
  scene3: 8.0,
};

export const VideoWithVoiceover: React.FC = () => {
  const { fps } = useVideoConfig();

  const scene1Frames = Math.round(SCENE_DURATIONS.scene1 * fps);
  const scene2Frames = Math.round(SCENE_DURATIONS.scene2 * fps);

  return (
    <>
      <Sequence from={0} durationInFrames={scene1Frames}>
        <Audio src={staticFile("audio/project/project-scene1.mp3")} />
        <Scene1Visual />
      </Sequence>

      <Sequence from={scene1Frames} durationInFrames={scene2Frames}>
        <Audio src={staticFile("audio/project/project-scene2.mp3")} />
        <Scene2Visual />
      </Sequence>
    </>
  );
};

Tips for Best Results

1. Use character presets: Don't read screen text literally - use narrator or expert for natural flow
2. Punctuation matters: Use periods for pauses, commas for brief breaks
3. Numbers: Write out numbers ("five hundred" not "500") for natural speech
4. Abbreviations: Write full words ("twenty-four hours" not "24h")
5. Scene-by-scene: Different scenes can have different characters (dramatic intro, calm CTA)
6. Fine-tune: Use --scene to regenerate individual scenes without redoing everything
7. Request stitching: Keeps voice consistent across all scenes

Workflow Example

# 1. Create scenes.json with your script
# 2. Generate all scenes with narrator style
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/my-video-scenes.json \
  --character narrator \
  --output-dir public/audio/my-video/

# 3. Preview in Remotion, notice scene2 starts too early
# 4. Regenerate just scene2 with updated text
node .claude/skills/elevenlabs-remotion-skill/generate.js \
  --scenes remotion/my-video-scenes.json \
  --scene scene2 \
  --new-text "Slightly longer text to fill the visual timing" \
  --output-dir public/audio/my-video/

# 5. Update video composition with new duration from info.json
# 6. Repeat until timing is perfect