Gemini TTS - Text-to-Speech with Google Gemini API

A TypeScript application that converts text to speech using Google's Gemini API with native TTS capabilities.

Features

• 🎤 Convert text files to high-quality speech audio
• 🎵 30 different voice options available
• 🌍 Supports multiple languages (including Sinhala)
• 📁 Easy file-based input
• 🔧 TypeScript for better development experience
• ⚡ Uses the latest Gemini 2.5 TTS models

Prerequisites

• Node.js 18 or later
• pnpm (recommended) or npm
• A Google Gemini API key

Installation

1. Clone this repository or download the files
2. Install dependencies:

pnpm install

Or if you prefer npm:

npm install

3. Set up your environment variables:

Create a .env file in the root directory:

GEMINI_API_KEY=your_gemini_api_key_here

Get your API key from: https://aistudio.google.com/app/apikey

Usage

Quick Start

1. Make sure your text is in the text.txt file (it's already there with Sinhala text)
2. Run the application:

# Development mode (with ts-node)
pnpm dev

# Or build and run
pnpm build
pnpm start

3. The audio file will be generated as sinhala_text_audio.wav

Available Voices

The application supports 30 different voices:

• Bright: Zephyr, Autonoe
• Upbeat: Puck, Laomedeia
• Firm: Kore, Orus, Alnilam
• Informative: Charon, Rasalgethi
• Excitable: Fenrir
• Youthful: Leda
• Easy-going: Umbriel, Callirrhoe
• Clear: Erinome, Iapetus
• Breezy: Aoede
• Breathy: Enceladus
• Smooth: Algieba, Despina
• Gravelly: Algenib
• Soft: Achernar
• Mature: Gacrux
• Casual: Zubenelgenubi
• Forward: Pulcherrima
• Even: Schedar
• Friendly: Achird
• Lively: Sadachbia
• Knowledgeable: Sadaltager
• Gentle: Vindemiatrix
• Warm: Sulafat

Customizing Voice and Output

You can modify the voice and output filename in src/index.ts:

await tts.convertFileToSpeech('text.txt', {
  voiceName: 'Puck', // Change to any available voice
  outputFile: 'my_custom_audio.wav'
});

Supported Languages

The Gemini TTS API supports 24 languages including:

• English (US, India)
• Arabic (Egyptian)
• German, Spanish, French
• Hindi, Indonesian, Italian
• Japanese, Korean
• Portuguese (Brazil)
• Russian, Dutch, Polish
• Thai, Turkish, Vietnamese
• Romanian, Ukrainian
• Bengali, Marathi, Tamil, Telugu

Note: While Sinhala isn't officially listed, the API may auto-detect and process it.

Project Structure

gemini-tts/
├── src/
│   └── index.ts          # Main TypeScript application
├── dist/                 # Compiled JavaScript (after build)
├── text.txt             # Input text file (Sinhala content)
├── package.json         # Dependencies and scripts
├── tsconfig.json        # TypeScript configuration
└── README.md           # This file

Scripts

• pnpm dev - Run in development mode with ts-node
• pnpm build - Compile TypeScript to JavaScript
• pnpm start - Run the compiled JavaScript
• pnpm clean - Clean the dist directory

API Usage

The application uses the Gemini 2.5 Flash Preview TTS model:

const response = await this.ai.models.generateContent({
  model: "gemini-2.5-flash-preview-tts",
  contents: [{ 
    role: "user", 
    parts: [{ text: `Please read this text aloud: ${text}` }] 
  }],
  config: {
    responseModalities: ['AUDIO'],
    speechConfig: {
      voiceConfig: {
        prebuiltVoiceConfig: { 
          voiceName: 'Kore' 
        }
      }
    }
  }
});

Error Handling

The application includes comprehensive error handling for:

• Missing API keys
• File reading errors
• API response errors
• Audio file saving errors

Limitations

• TTS models accept text-only inputs
• Context window limit of 32k tokens
• Audio output is in WAV format at 24kHz
• Preview feature - may have usage limits

Troubleshooting

Common Issues

1. "GEMINI_API_KEY is required"

   • Make sure you've created a .env file with your API key
   • Verify the API key is correct

2. "Failed to read file text.txt"

   • Ensure the text.txt file exists in the root directory
   • Check file permissions

3. "No audio data received from Gemini API"

   • Check your API key has TTS permissions
   • Verify the text isn't too long (32k token limit)

Contributing

Feel free to submit issues and enhancement requests!

License

MIT License - see LICENSE file for details.

References

• Gemini API Documentation
• Google AI Studio
• TypeScript Documentation