Support playing as it is generating for Android (#477)

 package com.k2fsa.sherpa.onnx
 
 import android.content.res.AssetManager
-import android.media.MediaPlayer
+import android.media.*
 import android.net.Uri
 import android.os.Bundle
 import android.util.Log
@@ -23,6 +23,10 @@ class MainActivity : AppCompatActivity() {
     private lateinit var generate: Button
     private lateinit var play: Button
 
+    // see
+    // https://developer.android.com/reference/kotlin/android/media/AudioTrack
+    private lateinit var track: AudioTrack
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
@@ -31,6 +35,10 @@ class MainActivity : AppCompatActivity() {
         initTts()
         Log.i(TAG, "Finish initializing TTS")
 
+        Log.i(TAG, "Start to initialize AudioTrack")
+        initAudioTrack()
+        Log.i(TAG, "Finish initializing AudioTrack")
+
         text = findViewById(R.id.text)
         sid = findViewById(R.id.sid)
         speed = findViewById(R.id.speed)
@@ -51,6 +59,33 @@ class MainActivity : AppCompatActivity() {
         play.isEnabled = false
     }
 
+    private fun initAudioTrack() {
+        val sampleRate = tts.sampleRate()
+        val bufLength = (sampleRate * 0.1).toInt()
+        Log.i(TAG, "sampleRate: ${sampleRate}, buffLength: ${bufLength}")
+
+        val attr = AudioAttributes.Builder().setContentType(AudioAttributes.CONTENT_TYPE_SPEECH)
+            .setUsage(AudioAttributes.USAGE_MEDIA)
+            .build()
+
+        val format = AudioFormat.Builder()
+            .setEncoding(AudioFormat.ENCODING_PCM_FLOAT)
+            .setChannelMask(AudioFormat.CHANNEL_OUT_MONO)
+            .setSampleRate(sampleRate)
+            .build()
+
+        track = AudioTrack(
+            attr, format, bufLength, AudioTrack.MODE_STREAM,
+            AudioManager.AUDIO_SESSION_ID_GENERATE
+        )
+        track.play()
+    }
+
+    // this function is called from C++
+    private fun callback(samples: FloatArray) {
+        track.write(samples, 0, samples.size, AudioTrack.WRITE_BLOCKING)
+    }
+
     private fun onClickGenerate() {
         val sidInt = sid.text.toString().toIntOrNull()
         if (sidInt == null || sidInt < 0) {
@@ -79,16 +114,28 @@ class MainActivity : AppCompatActivity() {
             return
         }
 
+        track.pause()
+        track.flush()
+        track.play()
+
         play.isEnabled = false
-        val audio = tts.generate(text = textStr, sid = sidInt, speed = speedFloat)
+        Thread {
+            val audio = tts.generateWithCallback(
+                text = textStr,
+                sid = sidInt,
+                speed = speedFloat,
+                callback = this::callback
+            )
 
             val filename = application.filesDir.absolutePath + "/generated.wav"
             val ok = audio.samples.size > 0 && audio.save(filename)
             if (ok) {
+                runOnUiThread {
                     play.isEnabled = true
-            // Play automatically after generation
-            onClickPlay()
+                    track.stop()
+                }
             }
+        }.start()
     }
 
     private fun onClickPlay() {

@@ -54,6 +54,8 @@ class OfflineTts(
         }
     }
 
+    fun sampleRate() = getSampleRate(ptr)
+
     fun generate(
         text: String,
         sid: Int = 0,
@@ -66,6 +68,19 @@ class OfflineTts(
         )
     }
 
+    fun generateWithCallback(
+        text: String,
+        sid: Int = 0,
+        speed: Float = 1.0f,
+        callback: (samples: FloatArray) -> Unit
+    ): GeneratedAudio {
+        var objArray = generateWithCallbackImpl(ptr, text = text, sid = sid, speed = speed, callback=callback)
+        return GeneratedAudio(
+            samples = objArray[0] as FloatArray,
+            sampleRate = objArray[1] as Int
+        )
+    }
+
     fun allocate(assetManager: AssetManager? = null) {
         if (ptr == 0L) {
             if (assetManager != null) {
@@ -97,6 +112,7 @@ class OfflineTts(
     ): Long
 
     private external fun delete(ptr: Long)
+    private external fun getSampleRate(ptr: Long): Int
 
     // The returned array has two entries:
     //  - the first entry is an 1-D float array containing audio samples.
@@ -109,6 +125,14 @@ class OfflineTts(
         speed: Float = 1.0f
     ): Array<Any>
 
+    external fun generateWithCallbackImpl(
+        ptr: Long,
+        text: String,
+        sid: Int = 0,
+        speed: Float = 1.0f,
+        callback: (samples: FloatArray) -> Unit
+    ): Array<Any>
+
     companion object {
         init {
             System.loadLibrary("sherpa-onnx-jni")

@@ -2,6 +2,10 @@ package com.k2fsa.sherpa.onnx
 
 import android.content.res.AssetManager
 
+fun callback(samples: FloatArray): Unit {
+  println("callback got called with ${samples.size} samples");
+}
+
 fun main() {
   testTts()
   testAsr()
@@ -22,7 +26,7 @@ fun testTts() {
     )
   )
   val tts = OfflineTts(config=config)
-  val audio = tts.generate(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.”")
+  val audio = tts.generateWithCallback(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.”", callback=::callback)
   audio.save(filename="test-en.wav")
 }
 

@@ -172,57 +172,57 @@ def get_vits_models() -> List[TtsModel]:
             lang="zh",
             rule_fsts="vits-zh-aishell3/rule.fst",
         ),
-        TtsModel(
-            model_dir="vits-zh-hf-doom",
-            model_name="doom.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-doom/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-echo",
-            model_name="echo.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-echo/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-zenyatta",
-            model_name="zenyatta.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-zenyatta/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-abyssinvoker",
-            model_name="abyssinvoker.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-abyssinvoker/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-keqing",
-            model_name="keqing.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-keqing/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-eula",
-            model_name="eula.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-eula/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-bronya",
-            model_name="bronya.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-bronya/rule.fst",
-        ),
-        TtsModel(
-            model_dir="vits-zh-hf-theresa",
-            model_name="theresa.onnx",
-            lang="zh",
-            rule_fsts="vits-zh-hf-theresa/rule.fst",
-        ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-doom",
+        #      model_name="doom.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-doom/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-echo",
+        #      model_name="echo.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-echo/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-zenyatta",
+        #      model_name="zenyatta.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-zenyatta/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-abyssinvoker",
+        #      model_name="abyssinvoker.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-abyssinvoker/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-keqing",
+        #      model_name="keqing.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-keqing/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-eula",
+        #      model_name="eula.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-eula/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-bronya",
+        #      model_name="bronya.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-bronya/rule.fst",
+        #  ),
+        #  TtsModel(
+        #      model_dir="vits-zh-hf-theresa",
+        #      model_name="theresa.onnx",
+        #      lang="zh",
+        #      rule_fsts="vits-zh-hf-theresa/rule.fst",
+        #  ),
         # English (US)
         TtsModel(model_dir="vits-vctk", model_name="vits-vctk.onnx", lang="en"),
-        TtsModel(model_dir="vits-ljs", model_name="vits-ljs.onnx", lang="en"),
+        #  TtsModel(model_dir="vits-ljs", model_name="vits-ljs.onnx", lang="en"),
         # fmt: on
     ]
 
@@ -238,8 +238,8 @@ def main():
     template = environment.from_string(s)
     d = dict()
 
-    #  all_model_list = get_vits_models()
-    all_model_list = get_piper_models()
+    all_model_list = get_vits_models()
+    all_model_list += get_piper_models()
     all_model_list += get_coqui_models()
 
     num_models = len(all_model_list)

@@ -11,13 +11,15 @@
 // android-ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include
 #include "jni.h"  // NOLINT
 
+#include <fstream>
+#include <functional>
 #include <strstream>
 #include <utility>
+
 #if __ANDROID_API__ >= 9
 #include "android/asset_manager.h"
 #include "android/asset_manager_jni.h"
 #endif
-#include <fstream>
 
 #include "sherpa-onnx/csrc/macros.h"
 #include "sherpa-onnx/csrc/offline-recognizer.h"
@@ -502,11 +504,14 @@ class SherpaOnnxOfflineTts {
   explicit SherpaOnnxOfflineTts(const OfflineTtsConfig &config)
       : tts_(config) {}
 
-  GeneratedAudio Generate(const std::string &text, int64_t sid = 0,
-                          float speed = 1.0) const {
-    return tts_.Generate(text, sid, speed);
+  GeneratedAudio Generate(
+      const std::string &text, int64_t sid = 0, float speed = 1.0,
+      std::function<void(const float *, int32_t)> callback = nullptr) const {
+    return tts_.Generate(text, sid, speed, callback);
   }
 
+  int32_t SampleRate() const { return tts_.SampleRate(); }
+
  private:
   OfflineTts tts_;
 };
@@ -628,6 +633,13 @@ JNIEXPORT void JNICALL Java_com_k2fsa_sherpa_onnx_OfflineTts_delete(
   delete reinterpret_cast<sherpa_onnx::SherpaOnnxOfflineTts *>(ptr);
 }
 
+SHERPA_ONNX_EXTERN_C
+JNIEXPORT jint JNICALL Java_com_k2fsa_sherpa_onnx_OfflineTts_getSampleRate(
+    JNIEnv *env, jobject /*obj*/, jlong ptr) {
+  return reinterpret_cast<sherpa_onnx::SherpaOnnxOfflineTts *>(ptr)
+      ->SampleRate();
+}
+
 // see
 // https://stackoverflow.com/questions/29043872/android-jni-return-multiple-variables
 static jobject NewInteger(JNIEnv *env, int32_t value) {
@@ -664,6 +676,43 @@ Java_com_k2fsa_sherpa_onnx_OfflineTts_generateImpl(JNIEnv *env, jobject /*obj*/,
 }
 
 SHERPA_ONNX_EXTERN_C
+JNIEXPORT jobjectArray JNICALL
+Java_com_k2fsa_sherpa_onnx_OfflineTts_generateWithCallbackImpl(
+    JNIEnv *env, jobject /*obj*/, jlong ptr, jstring text, jint sid,
+    jfloat speed, jobject callback) {
+  const char *p_text = env->GetStringUTFChars(text, nullptr);
+  SHERPA_ONNX_LOGE("string is: %s", p_text);
+
+  std::function<void(const float *, int32_t)> callback_wrapper =
+      [env, callback](const float *samples, int32_t n) {
+        jclass cls = env->GetObjectClass(callback);
+        jmethodID mid = env->GetMethodID(cls, "invoke", "([F)V");
+
+        jfloatArray samples_arr = env->NewFloatArray(n);
+        env->SetFloatArrayRegion(samples_arr, 0, n, samples);
+        env->CallVoidMethod(callback, mid, samples_arr);
+      };
+
+  auto audio =
+      reinterpret_cast<sherpa_onnx::SherpaOnnxOfflineTts *>(ptr)->Generate(
+          p_text, sid, speed, callback_wrapper);
+
+  jfloatArray samples_arr = env->NewFloatArray(audio.samples.size());
+  env->SetFloatArrayRegion(samples_arr, 0, audio.samples.size(),
+                           audio.samples.data());
+
+  jobjectArray obj_arr = (jobjectArray)env->NewObjectArray(
+      2, env->FindClass("java/lang/Object"), nullptr);
+
+  env->SetObjectArrayElement(obj_arr, 0, samples_arr);
+  env->SetObjectArrayElement(obj_arr, 1, NewInteger(env, audio.sample_rate));
+
+  env->ReleaseStringUTFChars(text, p_text);
+
+  return obj_arr;
+}
+
+SHERPA_ONNX_EXTERN_C
 JNIEXPORT jboolean JNICALL Java_com_k2fsa_sherpa_onnx_GeneratedAudio_saveImpl(
     JNIEnv *env, jobject /*obj*/, jstring filename, jfloatArray samples,
     jint sample_rate) {