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Android can’t recognize speech, so a typical Android device cannot recognize speech either. Or, is there a way it can?
The easiest way is to ask another application to do the recognition for us. Asking another application to do something in Android is called using intents.
Our target device must have at least one application that can process the Intent for speech recognition, which is called by the RecognizerIntent.ACTION_RECOGNIZE_SPEECH action.
One such app is Google Voice Search. It is one of the best recognizers available for Android and supports a lot of languages. This service requires Internet connection because the voice recognition occurs on Google servers. This app has a very simple Activity that informs users they can speak. The moment the user stops talking, the dialog is closed and our application (intent caller) receives an array of strings with the recognized speech.
A voice recognition sample
Let’s write a little sample app that demonstrates using voice search in applications.
Our application needs to do these things:
- Receive a request for voice recognition
- Check the availability of application for speech recognizing
- If speech recognizing is available, then call the intent for it and receive the results
- If speech recognizing is not available, then show the dialog for installing Google Voice Search and redirect the user to Google Play, if he wants
First, we create a class that implements the logic for speech recognition. Call this class SpeechRecognitionHelper
where we declare a static, public function run()
that will receive a request for launching a recognition:
public class SpeechRecognitionHelper {
public static void run(Activity callingActivity) {
if (isSpeechRecognitionActivityPresented(callingActivity) == true) {
startRecognition(callingActivity);
} else {
Toast.makeText(callingActivity, "In order to activate speech recognition you must install \"Google Voice Search\"", Toast.LENGTH_LONG).show();
installGoogleVoiceSearch(callingActivity);
}
}
}
As you can see, besides the run()
function we need to implement three other functions:
isSpeechRecognitionActivityPresented
– checks if the speech recognition application is present on the system
installGoogleVoiceSearch
– initializes the Google Voice Search installation process
startRecognition
– prepares the appropriate Intent and runs the recognition
To check if the device has an application for speech recognition, we can use the queryIntentActivities method in class PackageManager. This method gives a list of activities that can process the specified Intent. To receive an instance of the PackageManager, we can use getPackageManager.
Our code is shown below:
isSpeechRecognitionActivityPresented
private static boolean isSpeechRecognitionActivityPresented(Activity callerActivity) {
try {
PackageManager pm = callerActivity.getPackageManager();
List activities = pm.queryIntentActivities(new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
if (activities.size() != 0) { return true; }
} catch (Exception e) {
}
return false; }
Now implement the startRecognition
function. This function will form the appropriate Intent for launching the speech recognition Activity. You can find detailed information for how to do it on documentation page.
Source code:
private static void startRecognitionActivity(Activity callerActivity) {
Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Select an application"); intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_WEB_SEARCH); intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 1);
ownerActivity.startActivityForResult(intent, SystemData.VOICE_RECOGNITION_REQUEST_CODE);
}
And last, we’ll implement the installGoogleVoiceSearch
. This function will show the dialog, asking the user if he wants to install Google Voice Search and send him to Google Play, if he does.
private static void installGoogleVoiceSearch(final Activity ownerActivity) {
Dialog dialog = new AlertDialog.Builder(ownerActivity)
.setMessage("For recognition it’s necessary to install \"Google Voice Search\"") .setTitle("Install Voice Search from Google Play?") .setPositiveButton("Install", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
try {
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=com.google.android.voicesearch"));
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY | Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
ownerActivity.startActivity(intent);
} catch (Exception ex) {
}
}})
.setNegativeButton("Cancel", null) .create();
dialog.show(); }
That’s about it. We run the speech recognition Activity. Then request the user’s permission to install Voice Search and send him to Google Play if he consents. One thing we still need to do and that is gather the voice recognition results.
We send a request using the startActivityForResult function to gather results of the launched Activity. We also need to redefine a OnActivityResult method in our intent caller Activity. This can be done this way:
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == SystemData.VOICE_RECOGNITION_REQUEST_CODE && resultCode == RESULT_OK) {
ArrayList matches = data.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
if (matches.size() > 0) Toast.makeText(this, matches.get(0), Toast.LENGTH_LONG).show();
}
super.onActivityResult(requestCode, resultCode, data);
}
Now we’re ready
The created class SpeechRecognitionHelper
allows us to perform a speech recognition request by calling only one function run()
.
All that is needed for adding a recognition feature is to add this class in our project and call the run function in needed place. And then implement processing text results by redefining the onActivityResult method for the Activity that initiated the recognition call.
For additional information you can look at the Android Developers website. Here, you’ll find good examples showing how to do voice recognition, and importantly, how to get the available language list. You will need this list if you want to recognize a language other than the user’s default locale.
For fast integration of voice input in to your app, you can download and use this code for the SpeechRecognitionHelper class.
About the Authors
Stanislav works in the Software & Service Group at Intel Corporation. He has 10+ years of experience in software development. His main interest is optimization of performance, power consumption, and parallel programming. In his current role as an Application Engineer providing technical support for Intel-based devices, Stanislav works closely with software developers and SoC architects to help them achieve the best possible performance on Intel platforms. Stanislav holds a Master's degree in Mathematical Economics from the National Research University Higher School of Economics.
Mikhail is co-author of this blog and an Intel summer intern, who is studying computer science at Lobachevsky University. He likes to deep dive in to math and do Android programming tricks.
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