Add C# API for Kokoro TTS models (#1720)

dotnet-examples/kokoro-tts/Program.cs

@@ -0,0 +1,70 @@
+// Copyright (c)  2025  Xiaomi Corporation
+//
+// This file shows how to use a non-streaming Kokoro TTS model
+// for text-to-speech
+// Please refer to
+// https://k2-fsa.github.io/sherpa/onnx/pretrained_models/index.html
+// and
+// https://github.com/k2-fsa/sherpa-onnx/releases/tag/tts-models
+// to download pre-trained models
+using SherpaOnnx;
+using System.Runtime.InteropServices;
+
+class OfflineTtsDemo
+{
+  static void Main(string[] args)
+  {
+    var config = new OfflineTtsConfig();
+    config.Model.Kokoro.Model = "./kokoro-en-v0_19/model.onnx";
+    config.Model.Kokoro.Voices = "./kokoro-en-v0_19/voices.bin";
+    config.Model.Kokoro.Tokens = "./kokoro-en-v0_19/tokens.txt";
+    config.Model.Kokoro.DataDir = "./kokoro-en-v0_19/espeak-ng-data";
+
+    config.Model.NumThreads = 2;
+    config.Model.Debug = 1;
+    config.Model.Provider = "cpu";
+
+    var tts = new OfflineTts(config);
+    var speed = 1.0f;
+    var text = "Today as always, men fall into two groups: slaves and free men. Whoever " +
+      "does not have two-thirds of his day for himself, is a slave, whatever " +
+      "he may be: a statesman, a businessman, an official, or a scholar. " +
+      "Friends fell out often because life was changing so fast. The easiest " +
+      "thing in the world was to lose touch with someone.";
+
+    // mapping of sid to voice name
+    // 0->af, 1->af_bella, 2->af_nicole, 3->af_sarah, 4->af_sky, 5->am_adam
+    // 6->am_michael, 7->bf_emma, 8->bf_isabella, 9->bm_george, 10->bm_lewis
+    var sid = 0;
+
+    var MyCallback = (IntPtr samples, int n, float progress) =>
+    {
+      float[] data = new float[n];
+      Marshal.Copy(samples, data, 0, n);
+      // You can process samples here, e.g., play them.
+      // See ../kokoro-tts-playback for how to play them
+      Console.WriteLine($"Progress {progress*100}%");
+
+      // 1 means to keep generating
+      // 0 means to stop generating
+      return 1;
+    };
+
+    var callback = new OfflineTtsCallbackProgress(MyCallback);
+
+    var audio = tts.GenerateWithCallbackProgress(text, speed, sid, callback);
+
+    var outputFilename = "./generated-kokoro-0.wav";
+    var ok = audio.SaveToWaveFile(outputFilename);
+
+    if (ok)
+    {
+      Console.WriteLine($"Wrote to {outputFilename} succeeded!");
+    }
+    else
+    {
+      Console.WriteLine($"Failed to write {outputFilename}");
+    }
+  }
+}
+