Android
Text zu Sprache (TTS)

Text zur Sprachbasis

layout_text_to_speech.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">
    
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content" 
        android:hint="Enter text here!"
        android:id="@+id/textToSpeak"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:layout_centerHorizontal="true"
        android:layout_below="@id/textToSpeak"
        android:id="@+id/btnSpeak"/>

</RelativeLayout>

AndroidTextToSpeechActivity.java

public class AndroidTextToSpeechActivity extends Activity implements
        TextToSpeech.OnInitListener {

    EditText textToSpeak = null;
    Button btnSpeak = null;
    TextToSpeech tts;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        textToSpeak = findViewById(R.id.textToSpeak);
        btnSpeak = findViewById(R.id.btnSpeak);
        btnSpeak.setEnabled(false);
        tts = new TextToSpeech(this, this);
        btnSpeak.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    speakOut();
                }
            });
    }

    @Override
    public void onDestroy() {
        // Don't forget to shutdown tts!
        if (tts != null) {
            tts.stop();
            tts.shutdown();
        }
        super.onDestroy();
    }

    @Override
    public void onInit(int status) {
        if (status == TextToSpeech.SUCCESS) {
            int result = tts.setLanguage(Locale.US);

            if (result == TextToSpeech.LANG_MISSING_DATA
                    || result == TextToSpeech.LANG_NOT_SUPPORTED) {
                Log.e("TTS", "This Language is not supported");
            } else {
                btnSpeak.setEnabled(true);
                speakOut();
            }
        } else {
            Log.e("TTS", "Initilization Failed!");
        }
    }

    private void speakOut() {
        String text = textToSpeak.getText().toString();
        if(text == null || text.isEmpty())
            return;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            String utteranceId=this.hashCode() + "";
            tts.speak(text, TextToSpeech.QUEUE_FLUSH, null, utteranceId);
        } else {
            tts.speak(text, TextToSpeech.QUEUE_FLUSH, null);
        }
    }
}

Die Sprache, die gesprochen werden soll, kann durch setLanguage() eines Locale für die setLanguage() -Methode festgelegt werden:

tts.setLanguage(Locale.CHINESE); // Chinese language

Die Anzahl der unterstützten Sprachen variiert zwischen den Android-Stufen. Mit der Methode isLanguageAvailable() kann isLanguageAvailable() werden, ob eine bestimmte Sprache unterstützt wird:

tts.isLanguageAvailable(Locale.CHINESE);

Der setPitch() kann mit der Methode setPitch() werden. Standardmäßig ist der Tonhöhenwert 1,0. Verwenden Sie Werte unter 1,0, um die Tonhöhe zu verringern, oder Werte über 1,0, um die Tonhöhe zu erhöhen:

tts.setPitch(0.6);

Die Sprechgeschwindigkeit kann mit setSpeechRate() . Die voreingestellte Sprachrate beträgt 1,0. Die Sprachrate kann verdoppelt werden, indem sie auf 2,0 eingestellt wird, oder halbiert werden, indem sie auf 0,5 gesetzt wird:

tts.setSpeechRate(2.0);

TextToSpeech-Implementierung über die APIs

Kalte beobachtbare Implementierung, gibt True aus, wenn die TTS-Engine das Sprechen beendet hat, fängt an zu sprechen, wenn sie abonniert ist. Beachten Sie, dass die API-Ebene 21 eine andere Methode zum Sprechen einführt:

public class RxTextToSpeech {

@Nullable RxTTSObservableOnSubscribe audio;

WeakReference<Context> contextRef;

public RxTextToSpeech(Context context) {
    this.contextRef = new WeakReference<>(context);
}

public void requestTTS(FragmentActivity activity, int requestCode) {
    Intent checkTTSIntent = new Intent();
    checkTTSIntent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
    activity.startActivityForResult(checkTTSIntent, requestCode);
}

public void cancelCurrent() {
    if (audio != null) {
        audio.dispose();
        audio = null;
    }
}

public Observable<Boolean> speak(String textToRead) {
    audio = new RxTTSObservableOnSubscribe(contextRef.get(), textToRead, Locale.GERMANY);
    return Observable.create(audio);
}


public static class RxTTSObservableOnSubscribe extends UtteranceProgressListener
        implements ObservableOnSubscribe<Boolean>,
        Disposable, Cancellable, TextToSpeech.OnInitListener {

    volatile boolean disposed;
    ObservableEmitter<Boolean> emitter;
    TextToSpeech textToSpeech;
    String text = "";
    Locale selectedLocale;
    Context context;

    public RxTTSObservableOnSubscribe(Context context, String text, Locale locale) {
        this.selectedLocale = locale;
        this.context = context;
        this.text = text;
    }

    @Override public void subscribe(ObservableEmitter<Boolean> e) throws Exception {
        this.emitter = e;
        if (context == null) {
            this.emitter.onError(new Throwable("nullable context, cannot execute " + text));
        } else {
            this.textToSpeech = new TextToSpeech(context, this);
        }
    }

    @Override @DebugLog public void dispose() {
        if (textToSpeech != null) {
            textToSpeech.setOnUtteranceProgressListener(null);
            textToSpeech.stop();
            textToSpeech.shutdown();
            textToSpeech = null;
        }
        disposed = true;
    }

    @Override public boolean isDisposed() {
        return disposed;
    }

    @Override public void cancel() throws Exception {
        dispose();
    }

    @Override public void onInit(int status) {

        int languageCode = textToSpeech.setLanguage(selectedLocale);

        if (languageCode == android.speech.tts.TextToSpeech.LANG_COUNTRY_AVAILABLE) {
            textToSpeech.setPitch(1);
            textToSpeech.setSpeechRate(1.0f);
            textToSpeech.setOnUtteranceProgressListener(this);
            performSpeak();
        } else {
            emitter.onError(new Throwable("language " + selectedLocale.getCountry() + " is not supported"));
        }
    }

    @Override public void onStart(String utteranceId) {
        //no-op
    }

    @Override public void onDone(String utteranceId) {
        this.emitter.onNext(true);
        this.emitter.onComplete();
    }

    @Override public void onError(String utteranceId) {
        this.emitter.onError(new Throwable("error TTS " + utteranceId));
    }

    void performSpeak() {

        if (isAtLeastApiLevel(21)) {
            speakWithNewApi();
        } else {
            speakWithOldApi();
        }
    }

    @RequiresApi(api = 21) void speakWithNewApi() {
        Bundle params = new Bundle();
        params.putString(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, "");
        textToSpeech.speak(text, TextToSpeech.QUEUE_ADD, params, uniqueId());
    }

    void speakWithOldApi() {
        HashMap<String, String> map = new HashMap<>();
        map.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, uniqueId());
        textToSpeech.speak(text, TextToSpeech.QUEUE_ADD, map);
    }

    private String uniqueId() {
        return UUID.randomUUID().toString();
    }
}

public static boolean isAtLeastApiLevel(int apiLevel) {
    return Build.VERSION.SDK_INT >= apiLevel;
}

}