text_to_speech_plus 🎙️ #

text_to_speech_plus is a modern, high-performance Flutter plugin for Text-to-Speech (TTS). It is designed for developers who need more than just basic voice output, offering advanced features like SSML, Real-time Visualization, Streaming, and Emotional Expression.

Compatible with: Android, iOS, Web, Windows, and macOS.

🚀 Top Features #

• 🎭 Expressive Styles: Use Cheerful, Angry, Sad, Whisper, and more.
• ⚡ AI-Ready Streaming: Enqueue chunks of text for immediate playback while your AI generates more.
• 📜 Full SSML Support: Precise control over pauses, emphasis, pronunciation, and volume.
• 👥 Multi-Speaker: Switch between different voices mid-conversation with zero delay.
• 📊 Real-time Amplitude: Build waveforms or sync character lip-movements with actual speech volume.
• 🔍 Smart Voice Discovery: Deep metadata including Neural, Premium, and Gender info.
• ⏱️ Precise Timestamps: Know exactly when every word or sentence is spoken.
• 🧠 Auto Language Detect: Automatically select the right voice based on input text script.

📦 Installation #

Add to your pubspec.yaml:

dependencies:
  text_to_speech_plus: ^1.0.0

Setup Requirements #

• Android: minSdkVersion 21 or higher.
• iOS: Target 12.0+ (Advanced SSML requires iOS 17.0+).
• macOS: Target 10.15+.

📖 Feature Showcase & Code #

1. Advanced Expressions & Emotions #

Request specific vocal tones to match the mood of your app.

final tts = TextToSpeechPlus();

// Speak with a specific style
await tts.speak("I am so excited to see you!", style: "cheerful");

// Or inject emotional context
await tts.speak("I'm sorry, I cannot do that.", emotion: "sad");

2. ⚡ Streaming (Enqueueing) for AI Chat #

Ideal for LLM integrations (like OpenAI or Gemini). Start speaking the first sentence as soon as it arrives!

// First sentence speaks immediately
await tts.speak("The weather in London is ", enqueue: false);

// Next chunks are added to the queue for seamless playback
await tts.speak("currently rainy with a high of 15 degrees.", enqueue: true);
await tts.speak(" I suggest taking an umbrella!", enqueue: true);

3. 📊 Real-time Audio Visualizer #

The onAmplitude callback provides the volume level (0.0 to 1.0) of the audio being output.

tts.onAmplitude((double amplitude) {
  // Use this value to drive a waveform widget or an avatar's mouth
  setState(() {
    mouthOpenness = amplitude; 
  });
});

await tts.speak("Watch the visualizer react to my voice!");

4. ⏱️ Live Word & Sentence Highlighting #

Synchronize your UI with the spoken text for reading or accessibility apps.

// Word-level progress
tts.onProgress((text, start, end, word, type) {
  print("Now speaking word: $word");
});

// Sentence-level detection
tts.onSentenceStart((text, start, end, sentence, type) {
  print("Beginning new sentence: $sentence");
});

5. 📜 SSML Playground #

Full support for Speech Synthesis Markup Language.

await tts.speakSsml("""
<speak>
  <p>First, I will speak normally.</p>
  <p><emphasis level="strong">Then with strong emphasis!</emphasis></p>
  <p>I can also <break time="2s"/> pause for two seconds.</p>
  <p><prosody pitch="high">And speak in a high pitch.</prosody></p>
</speak>
""");

6. 🗣️ Multi-Speaker Dialogs #

Define unique voices for different characters in a single session.

final voices = await tts.voices;
final maleVoice = voices.firstWhere((v) => v['gender'] == 'male');
final femaleVoice = voices.firstWhere((v) => v['gender'] == 'female');

await tts.speak("How are you doing today?", voice: maleVoice);
await tts.speak("I'm doing fantastic, thank you!", voice: femaleVoice, enqueue: true);

7. 🔍 Voice Discovery & Search (Gender, Type, Locale) #

Filter system voices to find exactly what you need, such as a Male or Female neural voice.

List<dynamic>? allVoices = await tts.getVoices();

// Find all premium female English voices
var myVoices = allVoices?.where((v) => 
    v['locale'] == 'en-US' && 
    v['gender'] == 'female' &&
    v['is_neural'] == '1'
).toList();

if (myVoices != null && myVoices.isNotEmpty) {
    await tts.setVoice(Map<String, String>.from(myVoices.first));
}

9. 👫 Changing Voice Gender #

Most TTS engines provide multiple voices per language. You can change the gender by selecting a specific voice that matches your preference.

List<dynamic>? allVoices = await tts.getVoices();

// Find a Male voice for English
var maleVoice = allVoices?.firstWhere((v) => 
    v['locale'] == 'en-US' && v['gender'] == 'male'
);

if (maleVoice != null) {
    await tts.setVoice(Map<String, String>.from(maleVoice));
}

🎧 Unified Event Callbacks #

📋 Full API Reference #

⚖️ License #

This project is licensed under the MIT License - see the LICENSE file for details.

Developed with ❤️ by Shirsh Shukla.