RecognizerApi.java

package com.todoroo.aacenc;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnCancelListener;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.speech.RecognitionListener;
import android.speech.RecognizerIntent;
import android.speech.SpeechRecognizer;
import android.util.Log;

@TargetApi(8)
public class RecognizerApi implements RecognitionListener {

	public static interface PlaybackExceptionHandler {
		public void playbackFailed(String file);
	}

    private String aacFile;

    private Context context;

    public static interface RecognizerApiListener {
    	public void onSpeechResult(String result);
    	public void onSpeechError(int error);
    }

    private RecognizerApiListener mListener;

    public RecognizerApi(Context context) {
    	this.context = context;

    	File dir = context.getFilesDir();
    	aacFile = dir.toString() + "/audio.aac";

    	sr = SpeechRecognizer.createSpeechRecognizer(context);
    }

    public void setTemporaryFile(String fileName) {
    	aacFile = context.getFilesDir().toString() + "/" + fileName;
    }

    public String getTemporaryFile() {
    	return aacFile;
    }

    public void setListener(RecognizerApiListener listener) {
    	this.mListener = listener;
    }

    public static void play(Activity activity, String file, PlaybackExceptionHandler handler) {
        MediaPlayer mediaPlayer = new MediaPlayer();

        try {
            mediaPlayer.setDataSource(file);
            mediaPlayer.prepare();
            mediaPlayer.start();
        } catch (Exception e) {
        	handler.playbackFailed(file);
        }
    }

    private AACEncoder encoder = new AACEncoder();
    private long speechStarted = 0;
    private SpeechRecognizer sr;
    private ProgressDialog speakPd;
    private ProgressDialog processingPd;
    private String processingMessage;

    /**
     * Start speech recognition
     *
     * @param callingPackage e.g. com.myapp.example
     * @param speakNowMessage e.g. "Speak now!"
     * @param processingMessage e.g. "Processing..."
     */
    public void start(String callingPackage, String speakNowMessage, String processingMessage) {
        sr.setRecognitionListener(this);

        Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
                RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
        intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, callingPackage);

        speechStarted = 0;
        baos.reset();

        speakPd = new ProgressDialog(context);
        speakPd.setMessage(speakNowMessage);
        speakPd.setIndeterminate(true);
        speakPd.setCancelable(true);
        speakPd.setOnCancelListener(new OnCancelListener() {
            @Override
            public void onCancel(DialogInterface dialog) {
                sr.cancel();
                onEndOfSpeech();
            }
        });

        speakPd.show();
        sr.startListening(intent);

        speechStarted = System.currentTimeMillis();
    }

    /**
     * Convert AAC file to M4A
     *
     * @param toFile
     * @throws IOException
     */
    public void convert(String toFile) throws IOException {
		new AACToM4A().convert(context, aacFile, toFile);
    }

    public void cancel() {
    	sr.cancel();
    }

    public void destroy() {
    	sr.setRecognitionListener(null);
    	sr.destroy();
    }

    // --- RecognitionListener methods --- //

    private ByteArrayOutputStream baos = new ByteArrayOutputStream();

    @Override
    public void onBeginningOfSpeech() {
    }

    @Override
    public void onBufferReceived(byte[] buffer) {
        if(speechStarted > 0) {
            try {
                baos.write(buffer);
            } catch (IOException e) {
                //
            }
        }
    }

    @Override
    public void onEndOfSpeech() {
        speakPd.dismiss();

        if(speechStarted == 0)
            return;

        processingPd = new ProgressDialog(context);
        processingPd.setMessage(processingMessage);
        processingPd.setIndeterminate(true);
        processingPd.setCancelable(true);
        processingPd.setOnCancelListener(new OnCancelListener() {
            @Override
            public void onCancel(DialogInterface dialog) {
                sr.cancel();
            }
        });
        processingPd.show();

        long delta = System.currentTimeMillis() - speechStarted;

        int sampleRate = (int) (baos.size() * 1000 / delta);
        sampleRate = 8000; // THIS IS A MAGIC NUMBER@?!!?!?!
        // can i has calculate?

        encoder.init(64000, 1, sampleRate, 16, aacFile);

        encoder.encode(baos.toByteArray());

        encoder.uninit();
    }

    @Override
    public void onError(int error) {
    	if (mListener != null)
    		mListener.onSpeechError(error);
        Log.w("Speech Error", "Error code: " + error);
    }

    @Override
    public void onEvent(int arg0, Bundle arg1) {
        //
    }

    @Override
    public void onPartialResults(Bundle partialResults) {
        onResults(partialResults);
    }

    @Override
    public void onReadyForSpeech(Bundle arg0) {
    }

    @Override
    public void onResults(Bundle results) {
    	processingPd.dismiss();
        ArrayList<String> strings = results.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
        if (mListener != null)
        	mListener.onSpeechResult(strings.size() == 0 ? "" : strings.get(0));
    }

    @Override
    public void onRmsChanged(float arg0) {
    }

}