Prevent the setLanguage() method in TextToSpeech to change the language

for all current TextToSpeech instances by only caching the language
value so it is used with each subsequent utterance for this instance.
Synchronize calls to the engine around a global mutex since the engine
isn't thread-safe, except for the stop() call which is meant to interrupt
the synthesis loop.

2 files changed, 20 insertions, 6 deletions

diff --git a/packages/TtsService/jni/android_tts_SynthProxy.cpp b/packages/TtsService/jni/android_tts_SynthProxy.cpp
index 68e3fb7..82067be 100644
--- a/packages/TtsService/jni/android_tts_SynthProxy.cpp
+++ b/packages/TtsService/jni/android_tts_SynthProxy.cpp
@@ -59,6 +59,9 @@ struct afterSynthData_t {
 // ----------------------------------------------------------------------------
 static fields_t javaTTSFields;
 
+// TODO move to synth member once we have multiple simultaneous engines running
+static Mutex engineMutex;
+
 // ----------------------------------------------------------------------------
 class SynthProxyJniStorage {
     public :
@@ -194,7 +197,6 @@ static tts_callback_status ttsSynthDoneCB(void *& userdata, uint32_t rate,
         if (bufferSize > 0) {
             prepAudioTrack(pJniData, pForAfter->streamType, rate, format, channel);
             if (pJniData->mAudioOut) {
-                pJniData->mAudioOut->start();
                 pJniData->mAudioOut->write(wav, bufferSize);
                 memset(wav, 0, bufferSize);
                 //LOGV("AudioTrack wrote: %d bytes", bufferSize);
@@ -331,6 +333,8 @@ android_tts_SynthProxy_setLanguage(JNIEnv *env, jobject thiz, jint jniData,
         return result;
     }
 
+    Mutex::Autolock l(engineMutex);
+
     SynthProxyJniStorage* pSynthData = (SynthProxyJniStorage*)jniData;
     const char *langNativeString = env->GetStringUTFChars(language, 0);
     const char *countryNativeString = env->GetStringUTFChars(country, 0);
@@ -390,6 +394,8 @@ android_tts_SynthProxy_setSpeechRate(JNIEnv *env, jobject thiz, jint jniData,
     char buffer [bufSize];
     sprintf(buffer, "%d", speechRate);
 
+    Mutex::Autolock l(engineMutex);
+
     SynthProxyJniStorage* pSynthData = (SynthProxyJniStorage*)jniData;
     LOGI("setting speech rate to %d", speechRate);
 
@@ -412,6 +418,8 @@ android_tts_SynthProxy_setPitch(JNIEnv *env, jobject thiz, jint jniData,
         return result;
     }
 
+    Mutex::Autolock l(engineMutex);
+
     int bufSize = 10;
     char buffer [bufSize];
     sprintf(buffer, "%d", pitch);
@@ -444,6 +452,8 @@ android_tts_SynthProxy_synthesizeToFile(JNIEnv *env, jobject thiz, jint jniData,
         return result;
     }
 
+    Mutex::Autolock l(engineMutex);
+
     // Retrieve audio parameters before writing the file header
     AudioSystem::audio_format encoding = DEFAULT_TTS_FORMAT;
     uint32_t rate = DEFAULT_TTS_RATE;
@@ -546,10 +556,12 @@ android_tts_SynthProxy_speak(JNIEnv *env, jobject thiz, jint jniData,
         return result;
     }
 
+    Mutex::Autolock l(engineMutex);
+
     SynthProxyJniStorage* pSynthData = (SynthProxyJniStorage*)jniData;
 
     if (pSynthData->mAudioOut) {
-        pSynthData->mAudioOut->stop();
+        pSynthData->mAudioOut->start();
     }
 
     afterSynthData_t* pForAfter = new (afterSynthData_t);
@@ -600,6 +612,8 @@ android_tts_SynthProxy_shutdown(JNIEnv *env, jobject thiz, jint jniData)
         return;
     }
 
+    Mutex::Autolock l(engineMutex);
+
     SynthProxyJniStorage* pSynthData = (SynthProxyJniStorage*)jniData;
     if (pSynthData->mNativeSynthInterface) {
         pSynthData->mNativeSynthInterface->shutdown();
diff --git a/packages/TtsService/src/android/tts/TtsService.java b/packages/TtsService/src/android/tts/TtsService.java
index 28801f8..9a4c97d 100755
--- a/packages/TtsService/src/android/tts/TtsService.java
+++ b/packages/TtsService/src/android/tts/TtsService.java
@@ -546,7 +546,7 @@ public class TtsService extends Service implements OnCompletionListener {
                     if (!synthAvailable) {
                         Thread.sleep(100);
                         Thread synth = (new Thread(new SynthThread()));
-                        synth.setPriority(Thread.MIN_PRIORITY);
+                        //synth.setPriority(Thread.MIN_PRIORITY);
                         synth.start();
                         return;
                     }
@@ -608,7 +608,7 @@ public class TtsService extends Service implements OnCompletionListener {
             }
         }
         Thread synth = (new Thread(new SynthThread()));
-        synth.setPriority(Thread.MIN_PRIORITY);
+        //synth.setPriority(Thread.MIN_PRIORITY);
         synth.start();
     }
 
@@ -623,7 +623,7 @@ public class TtsService extends Service implements OnCompletionListener {
                     if (!synthAvailable) {
                         Thread.sleep(100);
                         Thread synth = (new Thread(new SynthThread()));
-                        synth.setPriority(Thread.MIN_PRIORITY);
+                        //synth.setPriority(Thread.MIN_PRIORITY);
                         synth.start();
                         return;
                     }
@@ -677,7 +677,7 @@ public class TtsService extends Service implements OnCompletionListener {
             }
         }
         Thread synth = (new Thread(new SynthThread()));
-        synth.setPriority(Thread.MIN_PRIORITY);
+        //synth.setPriority(Thread.MIN_PRIORITY);
         synth.start();
     }