Support CMAS regulatory requirements

Fixes an issue where the 10.5s CMAS alert audio can be truncated
because the code relied on a timer and assumed playback would
start with zero lag. The alert audio file is changed to include
the full 10.5s alert sequence and is played in full without a
timer if the requested duration is 10.5s.

Change-Id: I0fff72579cad74bdb0ef5ab2fe6be8daf5c3b837
BZ: 25728174

1 files changed, 25 insertions, 6 deletions

diff --git a/src/com/android/cellbroadcastreceiver/CellBroadcastAlertAudio.java b/src/com/android/cellbroadcastreceiver/CellBroadcastAlertAudio.java
index 32f38aa4..d03e67a1 100644
--- a/src/com/android/cellbroadcastreceiver/CellBroadcastAlertAudio.java
+++ b/src/com/android/cellbroadcastreceiver/CellBroadcastAlertAudio.java
@@ -25,6 +25,7 @@ import android.content.res.Resources;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
 import android.media.MediaPlayer.OnErrorListener;
+import android.media.MediaPlayer.OnCompletionListener;
 import android.media.Ringtone;
 import android.media.RingtoneManager;
 import android.net.Uri;
@@ -85,6 +86,9 @@ public class CellBroadcastAlertAudio extends Service implements TextToSpeech.OnI
     /** Pause duration between alert sound and alert speech. */
     private static final int PAUSE_DURATION_BEFORE_SPEAKING_MSEC = 1000;
 
+    /** Duration of a CMAS alert. */
+    private static final int CMAS_DURATION_MSEC = 10500;
+
     /** Vibration uses the same on/off pattern as the CMAS alert tone */
     private static final long[] sVibratePattern = { 0, 2000, 500, 1000, 500, 1000, 500,
             2000, 500, 1000, 500, 1000};
@@ -296,7 +300,8 @@ public class CellBroadcastAlertAudio extends Service implements TextToSpeech.OnI
 
         // This extra should always be provided by CellBroadcastAlertService,
         // but default to 10.5 seconds just to be safe (CMAS requirement).
-        int duration = intent.getIntExtra(ALERT_AUDIO_DURATION_EXTRA, 10500);
+        int duration = intent.getIntExtra(ALERT_AUDIO_DURATION_EXTRA, CMAS_DURATION_MSEC);
+        if (DBG) log("Duration: " + duration);
 
         // Get text to speak (if enabled by user)
         mMessageBody = intent.getStringExtra(ALERT_AUDIO_MESSAGE_BODY);
@@ -380,6 +385,14 @@ public class CellBroadcastAlertAudio extends Service implements TextToSpeech.OnI
                 }
             });
 
+            mMediaPlayer.setOnCompletionListener(new OnCompletionListener() {
+                public void onCompletion(MediaPlayer mp) {
+                    if (DBG) log("Audio playback complete.");
+                    mHandler.sendMessage(mHandler.obtainMessage(ALERT_SOUND_FINISHED));
+                    return;
+                }
+            });
+
             try {
                 // Check if we are in a call. If we are, play the alert
                 // sound at a low volume to not disrupt the call.
@@ -394,22 +407,28 @@ public class CellBroadcastAlertAudio extends Service implements TextToSpeech.OnI
                         R.raw.attention_signal);
                 mAudioManager.requestAudioFocus(null, AudioManager.STREAM_NOTIFICATION,
                         AudioManager.AUDIOFOCUS_GAIN_TRANSIENT);
-                startAlarm(mMediaPlayer);
+                // if the duration isn't equal to one play of the full 10.5s file then play
+                // with looping enabled.
+                startAlarm(mMediaPlayer, duration != CMAS_DURATION_MSEC);
             } catch (Exception ex) {
                 loge("Failed to play alert sound: " + ex);
             }
         }
 
-        // stop alert after the specified duration
-        mHandler.sendMessageDelayed(mHandler.obtainMessage(ALERT_SOUND_FINISHED), duration);
+        // stop alert after the specified duration, unless we are playing the full 10.5s file once
+        // in which case we'll use the end of playback callback rather than a delayed message.
+        // This is to avoid the CMAS alert potentially being truncated due to audio playback lag.
+        if (duration != CMAS_DURATION_MSEC) {
+            mHandler.sendMessageDelayed(mHandler.obtainMessage(ALERT_SOUND_FINISHED), duration);
+        }
         mState = STATE_ALERTING;
     }
 
     // Do the common stuff when starting the alarm.
-    private static void startAlarm(MediaPlayer player)
+    private static void startAlarm(MediaPlayer player, boolean looping)
             throws java.io.IOException, IllegalArgumentException, IllegalStateException {
         player.setAudioStreamType(AudioManager.STREAM_NOTIFICATION);
-        player.setLooping(true);
+        player.setLooping(looping);
         player.prepare();
         player.start();
     }