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**WARNING:** ... (ellipsis) is NOT a reliable pause — it can be vocalized as a word/sound. Do not use ellipsis as a pause mechanism.

### Pronunciation Control

**Phonetic spelling (any model):** Write words as you want them pronounced:

• Janus → Jan-us
• nginx → engine-x
• Use dashes, capitals, apostrophes to guide pronunciation

**SSML phoneme tags (flash/turbo only):**

<phoneme alphabet="ipa" ph="ˈdʒeɪnəs">Janus</phoneme>

### Iterative Workflow

1. Generate → listen → identify pronunciation/pacing issues

2. Adjust: phonetic spellings, break tags, voice settings

3. Regenerate. If pauses aren't precise enough, add silence in post with ffmpeg rather than fighting the TTS engine.

Voice Cloning

### Instant Voice Clone

with open("sample.mp3", "rb") as f:
    voice = client.voices.ivc.create(
        name="My Voice",
        files=[f],
        remove_background_noise=True
    )
print(f"Voice ID: {voice.voice_id}")

• Use client.voices.ivc.create() (not client.voices.clone())
• Pass file handles in binary mode ("rb"), not paths
• Convert m4a first: ffmpeg -i input.m4a -codec:a libmp3lame -qscale:a 2 output.mp3
• Multiple samples (2-3 clips) improve accuracy
• Save voice ID for reuse

**Professional Voice Clone:** Requires Creator plan+, 30+ min audio. See reference.md (reference.md).

Sound Effects

Max 22 seconds per generation.

result = client.text_to_sound_effects.convert(
    text="Thunder rumbling followed by heavy rain",
    duration_seconds=10,
    prompt_influence=0.3
)
with open("thunder.mp3", "wb") as f:
    for chunk in result:
        f.write(chunk)

**Prompt tips:** Be specific — "Heavy footsteps on wooden floorboards, slow and deliberate, with creaking"

Music Generation

10 seconds to 5 minutes. Use client.music.compose() (not .generate()).

result = client.music.compose(
    prompt="Upbeat indie rock, catchy guitar riff, energetic drums, travel vlog",
    music_length_ms=60000,
    force_instrumental=True
)
with open("music.mp3", "wb") as f:
    for chunk in result:
        f.write(chunk)

**Prompt structure:** Genre, mood, instruments, tempo, use case. Add "no vocals" or use force_instrumental=True for background music.

Remotion Integration

### Complete Workflow: Script to Synchronized Scene

VOICEOVER-SCRIPT.md → voiceover.py → public/audio/ → Remotion composition
        ↓                  ↓               ↓                 ↓
  Scene narration    Generate MP3    Audio files     <Audio> component
  with durations     per scene       with timing     synced to scenes

### Step 1: Generate Per-Scene Audio

Use the toolkit's voiceover tool to generate audio for each scene:

# Generate voiceover files for each scene
python tools/voiceover.py --scene-dir public/audio/scenes --json

# Output:
# public/audio/scenes/
#   ├── scene-01-title.mp3
#   ├── scene-02-problem.mp3
#   ├── scene-03-solution.mp3
#   └── manifest.json  (durations for each file)

The manifest.json contains timing info:

{
  "scenes": [
    { "file": "scene-01-title.mp3", "duration": 4.2 },
    { "file": "scene-02-problem.mp3", "duration": 12.8 },
    { "file": "scene-03-solution.mp3", "duration": 15.3 }
  ],
  "totalDuration": 32.3
}

### Step 2: Use Audio in Remotion Composition

// src/Composition.tsx
import { Audio, staticFile, Series, useVideoConfig } from 'remotion';

// Import scene components
import { TitleSlide } from './scenes/TitleSlide';
import { ProblemSlide } from './scenes/ProblemSlide';
import { SolutionSlide } from './scenes/SolutionSlide';

// Scene durations (from manifest.json, converted to frames at 30fps)
const SCENE_DURATIONS = {
  title: Math.ceil(4.2 * 30),      // 126 frames
  problem: Math.ceil(12.8 * 30),   // 384 frames
  solution: Math.ceil(15.3 * 30),  // 459 frames
};

export const MainComposition: React.FC = () => {
  return (
    <>
      {/* Scene sequence */}
      <Series>
        <Series.Sequence durationInFrames={SCENE_DURATIONS.title}>
          <TitleSlide />
        </Series.Sequence>
        <Series.Sequence durationInFrames={SCENE_DURATIONS.problem}>
          <ProblemSlide />
        </Series.Sequence>
        <Series.Sequence durationInFrames={SCENE_DURATIONS.solution}>
          <SolutionSlide />
        </Series.Sequence>
      </Series>

      {/* Audio track - plays continuously across all scenes */}
      <Audio src={staticFile('audio/voiceover.mp3')} volume={1} />

      {/* Optional: Background music at lower volume */}
      <Audio src={staticFile('audio/music.mp3')} volume={0.15} />
    </>
  );
};

### Step 3: Per-Scene Audio (Alternative)

For more control, add audio to each scene individually:

// src/scenes/ProblemSlide.tsx
import { Audio, staticFile, useCurrentFrame } from 'remotion';

export const ProblemSlide: React.FC = () => {
  const frame = useCurrentFrame();

  return (
    <div style={{ /* slide styles */ }}>
      <h1>The Problem</h1>
      {/* Scene content */}

      {/* Audio starts when this scene starts (frame 0 of this sequence) */}
      <Audio src={staticFile('audio/scenes/scene-02-problem.mp3')} />
    </div>
  );
};

### Syncing Visuals to Voiceover

Calculate scene duration from audio, not the other way around:

// src/config/timing.ts
import manifest from '../../public/audio/scenes/manifest.json';

const FPS = 30