Replace Android system TTS engine (#508)

android/README.md

@@ -13,3 +13,8 @@ for usage.
 
 - [SherpaOnnxVadAsr](./SherpaOnnxVadAsr) It uses a VAD with a non-streaming
   ASR model.
+
+- [SherpaOnnxTts](./SherpaOnnxTts) It is for standalone text-to-speech.
+
+- [SherpaOnnxTtsEngine](./SherpaOnnxTtsEngine) It is for text-to-speech engine;
+   you can use it to replace the system TTS engine.

android/SherpaOnnxTts/app/src/main/java/com/k2fsa/sherpa/onnx/Tts.kt

@@ -56,6 +56,8 @@ class OfflineTts(
 
     fun sampleRate() = getSampleRate(ptr)
 
+    fun numSpeakers() = getNumSpeakers(ptr)
+
     fun generate(
         text: String,
         sid: Int = 0,
@@ -113,6 +115,7 @@ class OfflineTts(
 
     private external fun delete(ptr: Long)
     private external fun getSampleRate(ptr: Long): Int
+    private external fun getNumSpeakers(ptr: Long): Int
 
     // The returned array has two entries:
     //  - the first entry is an 1-D float array containing audio samples.

android/SherpaOnnxTtsEngine/.gitignore

@@ -0,0 +1,15 @@
+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties

android/SherpaOnnxTtsEngine/app/.gitignore

@@ -0,0 +1 @@
+/build

android/SherpaOnnxTtsEngine/app/build.gradle.kts

@@ -0,0 +1,71 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "com.k2fsa.sherpa.onnx.tts.engine"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "com.k2fsa.sherpa.onnx.tts.engine"
+        minSdk = 21
+        targetSdk = 34
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+        vectorDrawables {
+            useSupportLibrary = true
+        }
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+    buildFeatures {
+        compose = true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion = "1.5.1"
+    }
+    packaging {
+        resources {
+            excludes += "/META-INF/{AL2.0,LGPL2.1}"
+        }
+    }
+}
+
+dependencies {
+
+    implementation("androidx.core:core-ktx:1.12.0")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.6.2")
+    implementation("androidx.activity:activity-compose:1.8.2")
+    implementation(platform("androidx.compose:compose-bom:2023.08.00"))
+    implementation("androidx.compose.ui:ui")
+    implementation("androidx.compose.ui:ui-graphics")
+    implementation("androidx.compose.ui:ui-tooling-preview")
+    implementation("androidx.compose.material3:material3")
+    implementation("androidx.appcompat:appcompat:1.6.1")
+    implementation("com.google.android.material:material:1.9.0")
+    testImplementation("junit:junit:4.13.2")
+    androidTestImplementation("androidx.test.ext:junit:1.1.5")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
+    androidTestImplementation(platform("androidx.compose:compose-bom:2023.08.00"))
+    androidTestImplementation("androidx.compose.ui:ui-test-junit4")
+    debugImplementation("androidx.compose.ui:ui-tooling")
+    debugImplementation("androidx.compose.ui:ui-test-manifest")
+}

android/SherpaOnnxTtsEngine/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

android/SherpaOnnxTtsEngine/app/src/androidTest/java/com/k2fsa/sherpa/onnx/tts/engine/ExampleInstrumentedTest.kt

@@ -0,0 +1,24 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.k2fsa.sherpa.onnx.tts.engine", appContext.packageName)
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/AndroidManifest.xml

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <application
+        android:allowBackup="true"
+        android:dataExtractionRules="@xml/data_extraction_rules"
+        android:fullBackupContent="@xml/backup_rules"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.SherpaOnnxTtsEngine"
+        tools:targetApi="31">
+        <activity
+            android:name=".GetSampleText"
+            android:exported="true"
+            android:theme="@android:style/Theme.Translucent.NoTitleBar">
+            <intent-filter>
+                <action android:name="android.speech.tts.engine.GET_SAMPLE_TEXT" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+        <activity
+            android:name=".CheckVoiceData"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.speech.tts.engine.CHECK_TTS_DATA" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+        <activity
+            android:name=".InstallVoiceData"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.speech.tts.engine.INSTALL_TTS_DATA" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+
+        <service
+            android:name=".TtsService"
+            android:enabled="true"
+            android:exported="true"
+            android:label="@string/app_name">
+            <intent-filter>
+                <action android:name="android.intent.action.TTS_SERVICE" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+
+            <meta-data
+                android:name="android.speech.tts"
+                android:resource="@xml/tts_engine" />
+        </service>
+
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:theme="@style/Theme.SherpaOnnxTtsEngine">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.speech.tts.engine.CONFIGURE_ENGINE" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/CheckVoiceData.kt

@@ -0,0 +1,18 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.content.Intent
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+import android.speech.tts.TextToSpeech
+
+class CheckVoiceData : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val intent = Intent().apply {
+            putStringArrayListExtra(TextToSpeech.Engine.EXTRA_AVAILABLE_VOICES, arrayListOf(TtsEngine.lang))
+            putStringArrayListExtra(TextToSpeech.Engine.EXTRA_UNAVAILABLE_VOICES, arrayListOf())
+        }
+        setResult(TextToSpeech.Engine.CHECK_VOICE_DATA_PASS, intent)
+        finish()
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/GetSampleText.kt

@@ -0,0 +1,37 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.app.Activity
+import android.content.Intent
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+import android.speech.tts.TextToSpeech
+
+class GetSampleText : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        var result = TextToSpeech.LANG_AVAILABLE
+        var text: String = ""
+        when(TtsEngine.lang) {
+            "eng" -> {
+                text = "This is a text-to-speech engine with next generation Kaldi"
+            }
+            "zho", "cmn" -> {
+                text = "使用新一代 Kaldi 进行语音合成"
+            }
+            else -> {
+                result = TextToSpeech.LANG_NOT_SUPPORTED
+            }
+        }
+
+        val intent = Intent().apply{
+            if(result == TextToSpeech.LANG_AVAILABLE) {
+                putExtra(TextToSpeech.Engine.EXTRA_SAMPLE_TEXT, text)
+            } else {
+                putExtra("sampleText", text)
+            }
+        }
+
+        setResult(result, intent)
+        finish()
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/InstallVoiceData.kt

@@ -0,0 +1,12 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.app.Activity
+import android.os.Bundle
+import android.view.Window
+
+class InstallVoiceData : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        requestWindowFeature(Window.FEATURE_NO_TITLE)
+        super.onCreate(savedInstanceState)
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/MainActivity.kt

@@ -0,0 +1,141 @@
+@file:OptIn(ExperimentalMaterial3Api::class)
+
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.media.MediaPlayer
+import android.net.Uri
+import android.os.Bundle
+import android.util.Log
+import android.widget.Toast
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.wrapContentHeight
+import androidx.compose.material3.Button
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Slider
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextField
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import com.k2fsa.sherpa.onnx.tts.engine.ui.theme.SherpaOnnxTtsEngineTheme
+import java.io.File
+
+const val TAG = "sherpa-onnx-tts-engine"
+
+class MainActivity : ComponentActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        TtsEngine.createTts(this.application)
+        setContent {
+            SherpaOnnxTtsEngineTheme {
+                // A surface container using the 'background' color from the theme
+                Surface(
+                    modifier = Modifier.fillMaxSize(),
+                    color = MaterialTheme.colorScheme.background
+                ) {
+                    Scaffold(topBar = {
+                        TopAppBar(title = { Text("Next-gen Kaldi: TTS") })
+                    }) {
+                        Box(modifier = Modifier.padding(it)) {
+                            Column {
+                                Row {
+                                    Text("Speed")
+                                    Slider(
+                                        value = TtsEngine.speedState.value,
+                                        onValueChange = { TtsEngine.speed = it },
+                                        valueRange = 0.2F..3.0F
+                                    )
+                                }
+                                var testText by remember { mutableStateOf("") }
+
+                                OutlinedTextField(value = testText,
+                                    onValueChange = { testText = it },
+                                            label = { Text ("Test text") },
+                                    modifier = Modifier.fillMaxWidth().wrapContentHeight().padding(16.dp),
+                                    singleLine = false,
+                                )
+
+                                val numSpeakers = TtsEngine.tts!!.numSpeakers()
+                                if (numSpeakers > 1) {
+                                    Row {
+                                        Text("Speaker ID: (0-${numSpeakers - 1})")
+                                        Slider(
+                                            value = TtsEngine.speakerIdState.value.toFloat(),
+                                            onValueChange = { TtsEngine.speakerId = it.toInt() },
+                                            valueRange = 0.0f..(numSpeakers - 1).toFloat(),
+                                            steps = 1
+                                        )
+                                    }
+                                }
+                                Row {
+                                    Button(
+                                        modifier = Modifier.padding(20.dp),
+                                        onClick = {
+                                            Log.i(TAG, "Clicked, text: ${testText}")
+                                            if (testText.isBlank() || testText.isEmpty()) {
+                                                Toast.makeText(
+                                                    applicationContext,
+                                                    "Please input a test sentence",
+                                                    Toast.LENGTH_SHORT
+                                                ).show()
+                                            } else {
+                                                val audio = TtsEngine.tts!!.generate(
+                                                    text = testText,
+                                                    sid = TtsEngine.speakerId,
+                                                    speed = TtsEngine.speed,
+                                                )
+
+                                                val filename =
+                                                    application.filesDir.absolutePath + "/generated.wav"
+                                                val ok =
+                                                    audio.samples.size > 0 && audio.save(filename)
+
+                                                if (ok) {
+                                                    val mediaPlayer = MediaPlayer.create(
+                                                        applicationContext,
+                                                        Uri.fromFile(File(filename))
+                                                    )
+                                                    mediaPlayer.start()
+                                                } else {
+                                                    Log.i(TAG, "Failed to generate or save audio")
+                                                }
+                                            }
+                                        }) {
+                                        Text("Test")
+                                    }
+
+                                    Button(
+                                        modifier = Modifier.padding(20.dp),
+                                        onClick = {
+                                            TtsEngine.speakerId = 0
+                                            TtsEngine.speed = 1.0f
+                                            testText = ""
+                                        }) {
+                                        Text("Reset")
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/Tts.kt

@@ -0,0 +1 @@
+../../../../../../../../../../../SherpaOnnxTts/app/src/main/java/com/k2fsa/sherpa/onnx/Tts.kt

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/TtsEngine.kt

@@ -0,0 +1,158 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.app.Application
+import android.content.res.AssetManager
+import android.util.Log
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.mutableStateOf
+import com.k2fsa.sherpa.onnx.*
+import java.io.File
+import java.io.FileOutputStream
+import java.io.IOException
+
+object TtsEngine {
+    var tts: OfflineTts? = null
+
+    // https://en.wikipedia.org/wiki/ISO_639-3
+    // Example:
+    // eng for English,
+    // deu for German
+    // cmn for Mandarin
+    var lang: String? = null
+
+
+
+    val speedState: MutableState<Float> = mutableStateOf(1.0F)
+    val speakerIdState: MutableState<Int> = mutableStateOf(0)
+
+    var speed: Float
+        get() = speedState.value
+        set(value) {
+            speedState.value = value
+        }
+
+    var speakerId: Int
+        get() = speakerIdState.value
+        set(value) {
+            speakerIdState.value = value
+        }
+
+    private var modelDir: String? = null
+    private var modelName: String? = null
+    private var ruleFsts: String? = null
+    private var lexicon: String? = null
+    private var dataDir: String? = null
+    private var assets: AssetManager? = null
+
+    private var application: Application? = null
+
+    fun createTts(application: Application) {
+        Log.i(TAG, "Init Next-gen Kaldi TTS")
+        if (tts == null) {
+            this.application = application
+            initTts()
+        }
+    }
+
+    private fun initTts() {
+        assets = application?.assets
+
+        // The purpose of such a design is to make the CI test easier
+        // Please see
+        // https://github.com/k2-fsa/sherpa-onnx/blob/master/scripts/apk/generate-tts-apk-script.py
+        modelDir = null
+        modelName = null
+        ruleFsts = null
+        lexicon = null
+        dataDir = null
+        lang = null
+
+        // Please enable one and only one of the examples below
+
+        // Example 1:
+        // modelDir = "vits-vctk"
+        // modelName = "vits-vctk.onnx"
+        // lexicon = "lexicon.txt"
+        // lang = "eng"
+
+        // Example 2:
+        // https://github.com/k2-fsa/sherpa-onnx/releases/tag/tts-models
+        // https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-piper-en_US-amy-low.tar.bz2
+        // modelDir = "vits-piper-en_US-amy-low"
+        // modelName = "en_US-amy-low.onnx"
+        // dataDir = "vits-piper-en_US-amy-low/espeak-ng-data"
+        // lang = "eng"
+
+        // Example 3:
+        // modelDir = "vits-zh-aishell3"
+        // modelName = "vits-aishell3.onnx"
+        // ruleFsts = "vits-zh-aishell3/rule.fst"
+        // lexcion = "lexicon.txt"
+        // lang = "zho"
+
+        if (dataDir != null) {
+            val newDir = copyDataDir(modelDir!!)
+            modelDir = newDir + "/" + modelDir
+            dataDir = newDir + "/" + dataDir
+            assets = null
+        }
+
+        val config = getOfflineTtsConfig(
+            modelDir = modelDir!!, modelName = modelName!!, lexicon = lexicon ?: "",
+            dataDir = dataDir ?: "",
+            ruleFsts = ruleFsts ?: ""
+        )!!
+
+        tts = OfflineTts(assetManager = assets, config = config)
+    }
+
+
+    private fun copyDataDir(dataDir: String): String {
+        println("data dir is $dataDir")
+        copyAssets(dataDir)
+
+        val newDataDir = application!!.getExternalFilesDir(null)!!.absolutePath
+        println("newDataDir: $newDataDir")
+        return newDataDir
+    }
+
+    private fun copyAssets(path: String) {
+        val assets: Array<String>?
+        try {
+            assets = application!!.assets.list(path)
+            if (assets!!.isEmpty()) {
+                copyFile(path)
+            } else {
+                val fullPath = "${application!!.getExternalFilesDir(null)}/$path"
+                val dir = File(fullPath)
+                dir.mkdirs()
+                for (asset in assets.iterator()) {
+                    val p: String = if (path == "") "" else path + "/"
+                    copyAssets(p + asset)
+                }
+            }
+        } catch (ex: IOException) {
+            Log.e(TAG, "Failed to copy $path. ${ex.toString()}")
+        }
+    }
+
+    private fun copyFile(filename: String) {
+        try {
+            val istream = application!!.assets.open(filename)
+            val newFilename = application!!.getExternalFilesDir(null).toString() + "/" + filename
+            val ostream = FileOutputStream(newFilename)
+            // Log.i(TAG, "Copying $filename to $newFilename")
+            val buffer = ByteArray(1024)
+            var read = 0
+            while (read != -1) {
+                ostream.write(buffer, 0, read)
+                read = istream.read(buffer)
+            }
+            istream.close()
+            ostream.flush()
+            ostream.close()
+        } catch (ex: Exception) {
+            Log.e(TAG, "Failed to copy $filename, ${ex.toString()}")
+        }
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/TtsService.kt

@@ -0,0 +1,155 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import android.media.AudioFormat
+import android.speech.tts.SynthesisCallback
+import android.speech.tts.SynthesisRequest
+import android.speech.tts.TextToSpeech
+import android.speech.tts.TextToSpeechService
+import android.util.Log
+import com.k2fsa.sherpa.onnx.*
+
+/*
+https://developer.android.com/reference/java/util/Locale#getISO3Language()
+https://developer.android.com/reference/java/util/Locale#getISO3Country()
+
+eng, USA,
+eng, USA, POSIX
+eng,
+eng, GBR
+afr,
+afr, NAM
+afr, ZAF
+agq
+agq, CMR
+aka,
+aka, GHA
+amh,
+amh, ETH
+ara,
+ara, 001
+ara, ARE
+ara, BHR,
+deu
+deu, AUT
+deu, BEL
+deu, CHE
+deu, ITA
+deu, ITA
+deu, LIE
+deu, LUX
+spa,
+spa, 419
+spa, ARG,
+spa, BRA
+fra,
+fra, BEL,
+fra, FRA,
+
+E  Failed to check TTS data, no activity found for Intent
+{ act=android.speech.tts.engine.CHECK_TTS_DATA pkg=com.k2fsa.sherpa.chapter5 })
+
+E Failed to get default language from engine com.k2fsa.sherpa.chapter5
+Engine failed voice data integrity check (null return)com.k2fsa.sherpa.chapter5
+Failed to get default language from engine com.k2fsa.sherpa.chapter5
+
+*/
+
+class TtsService : TextToSpeechService() {
+    override fun onCreate() {
+        super.onCreate()
+
+        // see https://github.com/Miserlou/Android-SDK-Samples/blob/master/TtsEngine/src/com/example/android/ttsengine/RobotSpeakTtsService.java#L68
+        onLoadLanguage(TtsEngine.lang, "", "")
+    }
+
+    // https://developer.android.com/reference/kotlin/android/speech/tts/TextToSpeechService#onislanguageavailable
+    override fun onIsLanguageAvailable(_lang: String?, _country: String?, _variant: String?): Int {
+        val lang = _lang ?: ""
+
+        if (lang == TtsEngine.lang) {
+            return TextToSpeech.LANG_AVAILABLE
+        }
+
+        return TextToSpeech.LANG_NOT_SUPPORTED
+    }
+
+    override fun onGetLanguage(): Array<String> {
+        return arrayOf(TtsEngine.lang!!, "", "")
+    }
+
+    // https://developer.android.com/reference/kotlin/android/speech/tts/TextToSpeechService#onLoadLanguage(kotlin.String,%20kotlin.String,%20kotlin.String)
+    override fun onLoadLanguage(_lang: String?, _country: String?, _variant: String?): Int {
+        val lang = _lang ?: ""
+
+        if (lang == TtsEngine.lang) {
+            TtsEngine.createTts(application)
+            return TextToSpeech.LANG_AVAILABLE
+        } else {
+            return TextToSpeech.LANG_NOT_SUPPORTED
+        }
+    }
+
+    override fun onStop() {}
+
+    override fun onSynthesizeText(request: SynthesisRequest?, callback: SynthesisCallback?) {
+        if (request == null || callback == null) {
+            return
+        }
+        val language = request.language
+        val country = request.country
+        val variant = request.variant
+        val text = request.charSequenceText.toString()
+
+        val ret = onIsLanguageAvailable(language, country, variant)
+        if (ret == TextToSpeech.LANG_NOT_SUPPORTED) {
+            callback.error()
+            return
+        }
+        Log.i(TAG, "text: $text")
+        val tts = TtsEngine.tts!!
+
+        // Note that AudioFormat.ENCODING_PCM_FLOAT requires API level >= 24
+        // callback.start(tts.sampleRate(), AudioFormat.ENCODING_PCM_FLOAT, 1)
+
+        callback.start(tts.sampleRate(), AudioFormat.ENCODING_PCM_16BIT, 1)
+
+        if (text.isBlank() || text.isEmpty()) {
+            callback.done()
+            return
+        }
+
+        val ttsCallback = {floatSamples: FloatArray ->
+            // convert FloatArray to ByteArray
+            val samples = floatArrayToByteArray(floatSamples)
+            val maxBufferSize: Int = callback.maxBufferSize
+            var offset = 0
+            while (offset < samples.size) {
+                val bytesToWrite = Math.min(maxBufferSize, samples.size - offset)
+                callback.audioAvailable(samples, offset, bytesToWrite)
+                offset += bytesToWrite
+            }
+
+        }
+
+        Log.i(TAG, "text: $text")
+        tts.generateWithCallback(
+            text = text,
+            sid = TtsEngine.speakerId,
+            speed = TtsEngine.speed,
+            callback=ttsCallback,
+        )
+
+        callback.done()
+    }
+
+    private fun floatArrayToByteArray(audio: FloatArray): ByteArray {
+        // byteArray is actually a ShortArray
+        val byteArray = ByteArray(audio.size * 2)
+        for (i in audio.indices) {
+            val sample = (audio[i] * 32767).toInt()
+            byteArray[2 * i] = sample.toByte()
+            byteArray[2 * i + 1] = (sample shr 8).toByte()
+        }
+        return byteArray
+    }
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/ui/theme/Color.kt

@@ -0,0 +1,11 @@
+package com.k2fsa.sherpa.onnx.tts.engine.ui.theme
+
+import androidx.compose.ui.graphics.Color
+
+val Purple80 = Color(0xFFD0BCFF)
+val PurpleGrey80 = Color(0xFFCCC2DC)
+val Pink80 = Color(0xFFEFB8C8)
+
+val Purple40 = Color(0xFF6650a4)
+val PurpleGrey40 = Color(0xFF625b71)
+val Pink40 = Color(0xFF7D5260)

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/ui/theme/Theme.kt

@@ -0,0 +1,70 @@
+package com.k2fsa.sherpa.onnx.tts.engine.ui.theme
+
+import android.app.Activity
+import android.os.Build
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.dynamicDarkColorScheme
+import androidx.compose.material3.dynamicLightColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.SideEffect
+import androidx.compose.ui.graphics.toArgb
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalView
+import androidx.core.view.WindowCompat
+
+private val DarkColorScheme = darkColorScheme(
+    primary = Purple80,
+    secondary = PurpleGrey80,
+    tertiary = Pink80
+)
+
+private val LightColorScheme = lightColorScheme(
+    primary = Purple40,
+    secondary = PurpleGrey40,
+    tertiary = Pink40
+
+    /* Other default colors to override
+    background = Color(0xFFFFFBFE),
+    surface = Color(0xFFFFFBFE),
+    onPrimary = Color.White,
+    onSecondary = Color.White,
+    onTertiary = Color.White,
+    onBackground = Color(0xFF1C1B1F),
+    onSurface = Color(0xFF1C1B1F),
+    */
+)
+
+@Composable
+fun SherpaOnnxTtsEngineTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    // Dynamic color is available on Android 12+
+    dynamicColor: Boolean = true,
+    content: @Composable () -> Unit
+) {
+    val colorScheme = when {
+        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
+            val context = LocalContext.current
+            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
+        }
+
+        darkTheme -> DarkColorScheme
+        else -> LightColorScheme
+    }
+    val view = LocalView.current
+    if (!view.isInEditMode) {
+        SideEffect {
+            val window = (view.context as Activity).window
+            window.statusBarColor = colorScheme.primary.toArgb()
+            WindowCompat.getInsetsController(window, view).isAppearanceLightStatusBars = darkTheme
+        }
+    }
+
+    MaterialTheme(
+        colorScheme = colorScheme,
+        typography = Typography,
+        content = content
+    )
+}

android/SherpaOnnxTtsEngine/app/src/main/java/com/k2fsa/sherpa/onnx/tts/engine/ui/theme/Type.kt

@@ -0,0 +1,34 @@
+package com.k2fsa.sherpa.onnx.tts.engine.ui.theme
+
+import androidx.compose.material3.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+// Set of Material typography styles to start with
+val Typography = Typography(
+    bodyLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp,
+        lineHeight = 24.sp,
+        letterSpacing = 0.5.sp
+    )
+    /* Other default text styles to override
+    titleLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 22.sp,
+        lineHeight = 28.sp,
+        letterSpacing = 0.sp
+    ),
+    labelSmall = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Medium,
+        fontSize = 11.sp,
+        lineHeight = 16.sp,
+        letterSpacing = 0.5.sp
+    )
+    */
+)

android/SherpaOnnxTtsEngine/app/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>

android/SherpaOnnxTtsEngine/app/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>

android/SherpaOnnxTtsEngine/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

android/SherpaOnnxTtsEngine/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

android/SherpaOnnxTtsEngine/app/src/main/res/values/colors.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>

android/SherpaOnnxTtsEngine/app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Next-gen Kaldi: TTS</string>
+</resources>

android/SherpaOnnxTtsEngine/app/src/main/res/values/themes.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="Theme.SherpaOnnxTtsEngine" parent="android:Theme.Material.Light.NoActionBar" />
+</resources>

android/SherpaOnnxTtsEngine/app/src/main/res/xml/backup_rules.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample backup rules file; uncomment and customize as necessary.
+   See https://developer.android.com/guide/topics/data/autobackup
+   for details.
+   Note: This file is ignored for devices older that API 31
+   See https://developer.android.com/about/versions/12/backup-restore
+-->
+<full-backup-content>
+    <!--
+   <include domain="sharedpref" path="."/>
+   <exclude domain="sharedpref" path="device.xml"/>
+-->
+</full-backup-content>

android/SherpaOnnxTtsEngine/app/src/main/res/xml/data_extraction_rules.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample data extraction rules file; uncomment and customize as necessary.
+   See https://developer.android.com/about/versions/12/backup-restore#xml-changes
+   for details.
+-->
+<data-extraction-rules>
+    <cloud-backup>
+        <!-- TODO: Use <include> and <exclude> to control what is backed up.
+        <include .../>
+        <exclude .../>
+        -->
+    </cloud-backup>
+    <!--
+    <device-transfer>
+        <include .../>
+        <exclude .../>
+    </device-transfer>
+    -->
+</data-extraction-rules>

android/SherpaOnnxTtsEngine/app/src/main/res/xml/tts_engine.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<tts-engine xmlns:android="http://schemas.android.com/apk/res/android"
+    android:settingsActivity="com.k2fsa.sherpa.onnx.tts.engine.MainActivity"
+    >
+</tts-engine>

android/SherpaOnnxTtsEngine/app/src/test/java/com/k2fsa/sherpa/onnx/tts/engine/ExampleUnitTest.kt

@@ -0,0 +1,17 @@
+package com.k2fsa.sherpa.onnx.tts.engine
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}

android/SherpaOnnxTtsEngine/build.gradle.kts

@@ -0,0 +1,5 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+plugins {
+    id("com.android.application") version "8.2.0" apply false
+    id("org.jetbrains.kotlin.android") version "1.9.0" apply false
+}

android/SherpaOnnxTtsEngine/gradle.properties

@@ -0,0 +1,23 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app's APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official
+# Enables namespacing of each library's R class so that its R class includes only the
+# resources declared in the library itself and none from the library's dependencies,
+# thereby reducing the size of the R class for that library
+android.nonTransitiveRClass=true

android/SherpaOnnxTtsEngine/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Sun Dec 31 18:47:53 CST 2023
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.2-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

android/SherpaOnnxTtsEngine/gradlew

@@ -0,0 +1,185 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"

android/SherpaOnnxTtsEngine/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

android/SherpaOnnxTtsEngine/settings.gradle.kts

@@ -0,0 +1,17 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = "SherpaOnnxTtsEngine"
+include(":app")

sherpa-onnx/csrc/offline-tts-impl.h

@@ -34,6 +34,10 @@ class OfflineTtsImpl {
 
   // Return the sample rate of the generated audio
   virtual int32_t SampleRate() const = 0;
+
+  // Number of supported speakers.
+  // If it supports only a single speaker, then it return 0 or 1.
+  virtual int32_t NumSpeakers() const = 0;
 };
 
 }  // namespace sherpa_onnx

sherpa-onnx/csrc/offline-tts-vits-impl.h

@@ -74,6 +74,10 @@ class OfflineTtsVitsImpl : public OfflineTtsImpl {
     return model_->GetMetaData().sample_rate;
   }
 
+  int32_t NumSpeakers() const override {
+    return model_->GetMetaData().num_speakers;
+  }
+
   GeneratedAudio Generate(
       const std::string &_text, int64_t sid = 0, float speed = 1.0,
       GeneratedAudioCallback callback = nullptr) const override {

sherpa-onnx/csrc/offline-tts.cc

@@ -73,4 +73,6 @@ GeneratedAudio OfflineTts::Generate(
 
 int32_t OfflineTts::SampleRate() const { return impl_->SampleRate(); }
 
+int32_t OfflineTts::NumSpeakers() const { return impl_->NumSpeakers(); }
+
 }  // namespace sherpa_onnx

sherpa-onnx/csrc/offline-tts.h

@@ -86,6 +86,10 @@ class OfflineTts {
   // Return the sample rate of the generated audio
   int32_t SampleRate() const;
 
+  // Number of supported speakers.
+  // If it supports only a single speaker, then it return 0 or 1.
+  int32_t NumSpeakers() const;
+
  private:
   std::unique_ptr<OfflineTtsImpl> impl_;
 };

sherpa-onnx/jni/jni.cc

@@ -524,6 +524,8 @@ class SherpaOnnxOfflineTts {
 
   int32_t SampleRate() const { return tts_.SampleRate(); }
 
+  int32_t NumSpeakers() const { return tts_.NumSpeakers(); }
+
  private:
   OfflineTts tts_;
 };
@@ -652,6 +654,13 @@ JNIEXPORT jint JNICALL Java_com_k2fsa_sherpa_onnx_OfflineTts_getSampleRate(
       ->SampleRate();
 }
 
+SHERPA_ONNX_EXTERN_C
+JNIEXPORT jint JNICALL Java_com_k2fsa_sherpa_onnx_OfflineTts_getNumSpeakers(
+    JNIEnv *env, jobject /*obj*/, jlong ptr) {
+  return reinterpret_cast<sherpa_onnx::SherpaOnnxOfflineTts *>(ptr)
+      ->NumSpeakers();
+}
+
 // see
 // https://stackoverflow.com/questions/29043872/android-jni-return-multiple-variables
 static jobject NewInteger(JNIEnv *env, int32_t value) {

sherpa-onnx/python/csrc/offline-tts.cc

@@ -51,6 +51,7 @@ void PybindOfflineTts(py::module *m) {
       .def(py::init<const OfflineTtsConfig &>(), py::arg("config"),
            py::call_guard<py::gil_scoped_release>())
       .def_property_readonly("sample_rate", &PyClass::SampleRate)
+      .def_property_readonly("num_speakers", &PyClass::NumSpeakers)
       .def(
           "generate",
           [](const PyClass &self, const std::string &text, int64_t sid,