Question

I created a simple speech recognition service: for this purpose I created a subclass of android.speech.RecognitionService and I created an activity to start and stop this service.

My custom speech recognition service trivially uses the default speech recognizer, because my goal is simply to understand how the RecognitionService and RecognitionService.Callback classes work.

public class SimpleVoiceService extends RecognitionService {

    private SpeechRecognizer m_EngineSR;

    @Override
    public void onCreate() {
        super.onCreate();
        Log.i("SimpleVoiceService", "Service started");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i("SimpleVoiceService", "Service stopped");
    }

    @Override
    protected void onCancel(Callback listener) {
        m_EngineSR.cancel();
    }

    @Override
    protected void onStartListening(Intent recognizerIntent, Callback listener) {
        m_EngineSR.setRecognitionListener(new VoiceResultsListener(listener));
        m_EngineSR.startListening(recognizerIntent);
    }

    @Override
    protected void onStopListening(Callback listener) {
        m_EngineSR.stopListening();
    }


    /**
     * 
     */
    private class VoiceResultsListener implements RecognitionListener {

        private Callback m_UserSpecifiedListener;

        /**
         * 
         * @param userSpecifiedListener
         */
        public VoiceResultsListener(Callback userSpecifiedListener) {
            m_UserSpecifiedListener = userSpecifiedListener;
        }

        @Override
        public void onBeginningOfSpeech() {
            try {
                m_UserSpecifiedListener.beginningOfSpeech();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onBufferReceived(byte[] buffer) {
            try {
                m_UserSpecifiedListener.bufferReceived(buffer);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onEndOfSpeech() {
            try {
                m_UserSpecifiedListener.endOfSpeech();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onError(int error) {
            try {
                m_UserSpecifiedListener.error(error);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onEvent(int eventType, Bundle params) { ; }

        @Override
        public void onPartialResults(Bundle partialResults) {
            try {
                m_UserSpecifiedListener.partialResults(partialResults);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onReadyForSpeech(Bundle params) {
            try {
                m_UserSpecifiedListener.readyForSpeech(params);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onResults(Bundle results) {
            try {
                m_UserSpecifiedListener.results(results);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onRmsChanged(float rmsdB) {
            try {
                m_UserSpecifiedListener.rmsChanged(rmsdB);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }

}

I start and stop the service using the following activity.

public class VoiceServiceStarterActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Button startButton = new Button(this);
        startButton.setText("Start the service");
        startButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) { startVoiceService(); }
        });
        Button stopButton = new Button(this);
        stopButton.setText("Stop the service");
        stopButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) { stopVoiceService(); }
        });
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        layout.addView(startButton);
        layout.addView(stopButton);
        setContentView(layout);
    }

    private void startVoiceService() {
        startService(new Intent(this, SimpleVoiceService.class));
    }

    private void stopVoiceService() {
        stopService(new Intent(this, SimpleVoiceService.class));
    }
}

Finally I declared my service on the AndroidManifest.xml (see VoiceRecognition sample within Android SDK folder).

<service android:name="SimpleVoiceService"
         android:label="@string/service_name" >

    <intent-filter>
        <action android:name="android.speech.RecognitionService" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</service>

Then I installed this application on an Android device and I start it:
– when I start the service, it starts properly;
– when I stop it, it stops properly.

But if I launch the following code in a another activity, the activities List contains only an element, which is the default speech recognizer.

PackageManager pm = getPackageManager();
List<ResolveInfo> activities = pm.queryIntentActivities(
            new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);

Why is my speech recognizer not returned among those present in the system?

Answer 1

If you want queryIntentActivities(new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0) to pick up your activity (VoiceServiceStarterActivity) then you have to declare in your app’s Manifest that this activity handles RecognizerIntent.ACTION_RECOGNIZE_SPEECH, like this

<activity android:name="VoiceServiceStarterActivity">
  <intent-filter>
    <action android:name="android.speech.action.RECOGNIZE_SPEECH" />
    <category android:name="android.intent.category.DEFAULT" />
  </intent-filter>
  ...
</activity>

For more concrete code have a look at the project Kõnele (source code) which is essentially an open source implementation of the interfaces via which speech recognition is provided on Android, i.e. it covers:

• ACTION_RECOGNIZE_SPEECH
• ACTION_WEB_SEARCH
• RecognitionService

and uses open source speech recognition servers.