How to speed up the initialization of Text to speech

Question

I'm working on an application which needs to use the class Text to speech to be able to read a text. The thing is that the initialization is very slow, approximately 4 sec. I followed this tutorial : http://code.tutsplus.com/tutorials/use-text-to-speech-on-android-to-read-out-incoming-messages--cms-22524. I made some research but I didn't find really good answers or I miss them.

For example I tried this solution by calling my checkTTS function in a thread but no result where visible. Here and here, they said that my checkTTS function with intent is maybe not so useful and I can just see if my needed language is available.

So my questions :

• Can I really just check if my language exist, what is really the big difference between ACTION_CHECK_TTS_DATA and just check if language is available ?
• Can I improve something else ?

Here is my activity code :

public class MyActivity extends Activity {
    private Speaker _speaker;
    private final int CHECK_CODE = 0x1;
    private final int SHORT_DURATION = 1000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        System.out.println("I'm just before checkTTS");
        checkTTS();
    }


    private void checkTTS(){
        System.out.println("I'm in checkTTS");
        Intent check = new Intent();
        check.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
        startActivityForResult(check, CHECK_CODE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode == CHECK_CODE){
            if(resultCode == TextToSpeech.Engine.CHECK_VOICE_DATA_PASS){
                System.out.println("I'm in onActivityResult");
                _speaker = new Speaker(this);
            }else {
                Intent install = new Intent();
                install.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
                startActivity(install);
            }
        }
    }

    @Override
    protected void onDestroy() {    
        super.onDestroy();
        _speaker.destroy();
    }
}

And here is my Speaker class :

public class Speaker implements OnInitListener {
    private TextToSpeech _tts;
    private boolean _ready = false;
    private boolean _allowed = false;

    public Speaker(Context context){
        _tts = new TextToSpeech(context, this);
    }   

    public void setSpeedRate(float speechrate) {
        _tts.setSpeechRate(speechrate);
    }

    public boolean isAllowed(){
        return _allowed;
    }

    public void allow(boolean allowed){
        _allowed = allowed;
    }

    @Override
    public void onInit(int status) {
        System.out.println("I'm in onInit from Speaker");
        if(status == TextToSpeech.SUCCESS){
            _tts.setLanguage(Locale.UK);
            _ready = true;
        } else{
            _ready = false;
        }
    }

    public void speak(String text){
        if(_ready && _allowed) {
            HashMap<String, String> hash = new HashMap<String,String>();
            hash.put(TextToSpeech.Engine.KEY_PARAM_STREAM, String.valueOf(AudioManager.STREAM_NOTIFICATION));
            _tts.speak(text, TextToSpeech.QUEUE_ADD, hash);
        }
    }

    public boolean isSpeaking() {
        return _tts.isSpeaking();
    }

    public void pause(int duration){
        _tts.playSilence(duration, TextToSpeech.QUEUE_ADD, null);
    }

    public void stop() {
        _tts.stop();
    }

    public void destroy(){
        _tts.shutdown();
    }
}

Here is the log from eclipse :

15:14:58.897: D/dalvikvm(23966): GC_CONCURRENT freed ...
15:15:00.014: I/System.out(23966): I'm just before checkTTS
15:15:00.014: I/System.out(23966): I'm in checkTTS
15:15:00.046: D/AbsListView(23966): unregisterIRListener() is called 
15-13 15:15:01.272: I/System.out(23966): I'm in onActivityResult
15:15:01.311: I/TextToSpeech(23966): Sucessfully bound to com.samsung.SMT
15:15:01.663: D/AbsListView(23966): onVisibilityChanged() is called, visibility : 4
15:15:01.663: D/AbsListView(23966): unregisterIRListener() is called 
15:15:02.600: I/TextToSpeech(23966): Connected to ComponentInfo{com.samsung.SMT/...}
15:15:02.608: I/TextToSpeech(23966): onServiceConnected but waiting
15:15:02.608: I/System.out(23966): I'm in onInit from Speaker
15:15:02.616: I/System.out(23966): Speaker ready
15:15:02.616: I/TextToSpeech(23966): onServiceConnected waiting end

Thank you for your help, Best regards, Zed13

Ps : sorry for the mistakes...

Edit : funny facts, it seems to launched faster with samsung voices than with google voices...

Answer 1

1. According to the Android API, ACTION_CHECK_TTS_DATA "Starts the activity from the platform TextToSpeech engine to verify the proper installation and availability of the resource files on the system". In that case, does not make sense create a TTS instance until you receive CHECK_VOICE_DATA_PASS. Alternatively, if for some reason (state flag, etc) you are confident that the system has the required TTS resources installed, you may use a "optimistic approach", i.e., you skip this step, initialize a TTS instance (for example, in your onCreate method) and after check the available languages or if some language is supported. Since you are skipping a step (ACTION_CHECK_TTS_DATA), if everything succeed, your initialization will be quicker.

You can check the engines installed in the system looking to this code and use that information to launch more accurate ACTION_CHECK_TTS_DATA intents.

2. The rest of the code looks good from a performance point of view. However, keep in mind that you can launch ACTION_CHECK_TTS_DATA intent and initialize the TTS instance simultaneously! If something is missing the intent is already launched and TTS will not work as expected. If the device has all TTS resources, the intent will pass and TTS is already initialized. You can look to the Audio News app as an example of this behavior ;)