Shiny.Speech 2.1.0

Shiny.Speech

Cross-platform speech services for .NET MAUI and Blazor WebAssembly — speech-to-text, text-to-speech, audio capture, and audio playback with pluggable cloud providers.

Libraries

Getting Started

Native Platform Speech

Use the built-in OS speech engines — no cloud account needed. Works on MAUI (iOS, Android, Windows) and Blazor WebAssembly (via Web Speech API).

builder.Services.AddSpeechServices();
// Registers: ISpeechToTextService, ITextToSpeechService, IAudioSource, IAudioPlayer
// On Browser/WASM: auto-detected via OperatingSystem.IsBrowser()

Azure AI Speech (Cloud)

builder.Services.AddAzureSpeech("your-subscription-key", "your-region");

ElevenLabs (Cloud)

// Register both STT (Scribe) and TTS:
builder.Services.AddElevenLabsSpeech("your-api-key");

// Or pick one:
builder.Services.AddElevenLabsSpeechToText("your-api-key");
builder.Services.AddElevenLabsTextToSpeech("your-api-key");

Usage

Text-to-Speech

public class MyService(ITextToSpeechService tts)
{
    public async Task SpeakAsync()
    {
        await tts.SpeakAsync("Hello world!", new TextToSpeechOptions
        {
            SpeechRate = 1.2f,
            Pitch = 1.0f,
            Volume = 0.8f
        });
    }
}

VU Meter (Audio Level)

ITextToSpeechService and IAudioPlayer expose an AudioLevelChanged event that fires periodically while audio is playing with a normalized 0.0–1.0 RMS level. Check IsPlayerAnalysisSupported before binding UI.

if (tts.IsPlayerAnalysisSupported)
    tts.AudioLevelChanged += (s, level) =>
        MainThread.BeginInvokeOnMainThread(() => MyVuBar.Progress = level);

On Apple platforms, native TTS routes AVSpeechSynthesizer through AVAudioEngine + AVAudioPlayerNode so audio levels can be tapped. The engine is created lazily on first speak and kept warm across utterances — only the first utterance pays ~50–150 ms additional startup.

Speech-to-Text

The ISpeechToTextService uses a Start/Stop model with events, allowing multiple consumers to observe recognition results simultaneously.

public class MyService(ISpeechToTextService stt) : IDisposable
{
    public async Task StartListeningAsync()
    {
        var access = await stt.RequestAccess();
        if (access != AccessState.Available)
            return;

        // Subscribe to events
        stt.ResultReceived += OnResult;
        stt.KeywordHeard += OnKeyword;
        stt.Error += OnError;

        // Start listening (throws if already listening)
        await stt.Start(new SpeechRecognitionOptions
        {
            Culture = CultureInfo.GetCultureInfo("en-US"),
            SilenceTimeout = TimeSpan.FromSeconds(3),
            Keywords = ["Yes", "No", "Maybe"]
        });
    }

    public async Task StopListeningAsync()
    {
        await stt.Stop(); // no-op if not listening
        stt.ResultReceived -= OnResult;
        stt.KeywordHeard -= OnKeyword;
        stt.Error -= OnError;
    }

    void OnResult(object? sender, SpeechRecognitionResult result)
        => Console.WriteLine($"[{(result.IsFinal ? "FINAL" : "partial")}] {result.Text}");

    void OnKeyword(object? sender, string keyword)
        => Console.WriteLine($"Keyword detected: {keyword}");

    void OnError(object? sender, SpeechRecognitionError error)
        => Console.WriteLine($"Error: {error.Message}");

    public void Dispose() => StopListeningAsync().GetAwaiter().GetResult();
}

Extension Methods (Convenience)

// Simple: wait for silence (starts and stops automatically)
var text = await stt.ListenUntilSilence(cancellationToken: ct);

// Wake word: "Hey Computer, do something" → returns "do something"
var command = await stt.StatementAfterKeyword(["Hey Computer"], cancellationToken: ct);

// Wait for a specific keyword (with optional timeout)
var answer = await stt.WaitListenForKeywords(["Yes", "No"], timeout: TimeSpan.FromSeconds(30), cancellationToken: ct);

// Continuous keyword stream
await foreach (var keyword in stt.ListenForKeywords(["Up", "Down", "Left", "Right"], cancellationToken: ct))
{
    Console.WriteLine($"Direction: {keyword}");
}

Custom Cloud Provider

Implement ISpeechToTextProvider and/or ITextToSpeechProvider from Shiny.Speech.Cloud:

public class MyCloudSttProvider : ISpeechToTextProvider
{
    public event EventHandler<SpeechRecognitionError>? Error;

    public async IAsyncEnumerable<SpeechRecognitionResult> RecognizeAsync(
        Stream audioStream,
        SpeechRecognitionOptions? options = null,
        CancellationToken cancellationToken = default)
    {
        // Read PCM audio from audioStream (16kHz, 16-bit, mono)
        // Yield recognition results...

        // For continuous recognition, surface non-fatal errors (e.g. a transient
        // network blip between chunked requests) without aborting the session:
        // Error?.Invoke(this, new SpeechRecognitionError("network blip", ex));
    }
}

// Register:
builder.Services.AddCloudSpeechToText<MyCloudSttProvider>();

CloudSpeechToText subscribes to the provider's Error event and forwards it to the service-level ISpeechToTextService.Error, so app code only needs to wire one handler.

Platform Requirements

Browser (Blazor WebAssembly)

No manifest changes needed — the browser prompts the user for microphone access automatically. Include the JS interop module in your index.html:

<script src="shiny-speech.js"></script>

Note: IAudioSource captures raw PCM audio in the browser using the Web Audio API (getUserMedia + ScriptProcessorNode), downsampled to 16kHz 16-bit mono. Audio playback (IAudioPlayer) accepts any browser-supported format via a base64 data URL.

iOS/macOS

Add to Info.plist:

<key>NSSpeechRecognitionUsageDescription</key>
<string>Speech recognition description</string>
<key>NSMicrophoneUsageDescription</key>
<string>Microphone description</string>

Android

Add to AndroidManifest.xml:

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

MODIFY_AUDIO_SETTINGS is required for the TTS audio-level Visualizer and for the native STT beep suppression.