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      1 page.title=Dealing with Audio Output Hardware
      2 parent.title=Managing Audio Playback
      3 parent.link=index.html
      4 
      5 trainingnavtop=true
      6 previous.title=Managing Audio Focus
      7 previous.link=audio-focus.html
      8 
      9 @jd:body
     10 
     11  
     12 <div id="tb-wrapper"> 
     13 <div id="tb">
     14 
     15 <h2>This lesson teaches you to</h2>
     16 <ol>
     17   <li><a href="#CheckHardware">Check What Hardware is Being Used</a></li>
     18   <li><a href="#HandleChanges">Handle Changes in the Audio Output Hardware</a></li>
     19 </ol>
     20 
     21 
     22 <h2>You should also read</h2>
     23 <ul>
     24   <li><a href="{@docRoot}guide/topics/media/mediaplayer.html">Media Playback</a></li>
     25 </ul>
     26 
     27 
     28 </div> 
     29 </div>
     30 
     31 <p>Users have a number of alternatives when it comes to enjoying the audio from their Android
     32 devices. Most devices have a built-in speaker, headphone jacks for wired headsets, and many also
     33 feature Bluetooth connectivity and support for A2DP audio. </p>
     34 
     35  
     36 <h2 id="CheckHardware">Check What Hardware is Being Used</h2> 
     37  
     38 <p>How your app behaves might be affected by which hardware its output is being routed to.</p>
     39 
     40 <p>You can query the {@link android.media.AudioManager} to determine if the audio is currently
     41 being routed to the device speaker, wired headset, or attached Bluetooth device as shown in the
     42 following snippet:</p>
     43 
     44 <pre>
     45 if (isBluetoothA2dpOn()) {
     46     // Adjust output for Bluetooth.
     47 } else if (isSpeakerphoneOn()) {
     48     // Adjust output for Speakerphone.
     49 } else if (isWiredHeadsetOn()) {
     50     // Adjust output for headsets
     51 } else { 
     52     // If audio plays and noone can hear it, is it still playing?
     53 }
     54 </pre>
     55 
     56 
     57 <h2 id="HandleChanges">Handle Changes in the Audio Output Hardware</h2> 
     58 
     59 <p>When a headset is unplugged, or a Bluetooth device disconnected, the audio stream
     60 automatically reroutes to the built in speaker. If you listen to your music at as high a volume as I
     61 do, that can be a noisy surprise.</p>
     62 
     63 <p>Luckily the system broadcasts an {@link android.media.AudioManager#ACTION_AUDIO_BECOMING_NOISY}
     64 intent when this happens. Its good practice to register a {@link android.content.BroadcastReceiver}
     65 that listens for this intent whenever youre playing audio. In the case of music players, users
     66 typically expect the playback to be paused&mdash;while for games you may choose to significantly
     67 lower the volume.</p>
     68  
     69 <pre>
     70 private class NoisyAudioStreamReceiver extends BroadcastReceiver {
     71     &#64;Override
     72     public void onReceive(Context context, Intent intent) {
     73         if (AudioManager.ACTION_AUDIO_BECOMING_NOISY.equals(intent.getAction())) {
     74             // Pause the playback
     75         }
     76     }
     77 }
     78 
     79 private IntentFilter intentFilter = new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY);
     80 
     81 private void startPlayback() {
     82     registerReceiver(myNoisyAudioStreamReceiver(), intentFilter);
     83 }
     84 
     85 private void stopPlayback() {
     86     unregisterReceiver(myNoisyAudioStreamReceiver);
     87 }
     88 </pre>
     89