實作中斷處理

TVSDK提供API以及處理中斷期間的範常式式碼。

若要實施中斷處理，包括在中斷期間提供替代內容：

1. 設定應用程式以偵測即時資料流資訊清單中的中斷標籤。

   public void createMediaPlayer {
       ...
       String[] blackoutTags = {BLACKOUTTAG};
       PSDKConfig.setSubscribedTags(blackoutTags);
       // For example: PTSDKConfig.setSubscribedTags({"#EXT-OATCLS-SCTE35"});
   }
   

2. 為前景和背景資料流中的定時中繼資料事件建立事件接聽程式。

   private MediaPlayer createMediaPlayer() {
       mediaPlayer.addEventListener(MediaPlayer.Event.PLAYBACK, _playbackEventListener);
       mediaPlayer.addEventListener(MediaPlayer.Event.BLACKOUTS, _blackoutsEventListener);
   }
   

3. 針對前景和背景資料流，實作計時中繼資料事件處理常式。

   前景：

   private final MediaPlayer.PlaybackEventListener _playbackEventListener =
             new MediaPlayer.PlaybackEventListener() {
       ...
   
       @override
       public void onTimedMetadata(TimedMetadata timedMetadata) {
           if (timedMetadata.getName().equal(BLACKOUTTAG) &&
               !_timedMetadataList.contains(timedMetadata)) {
                 _timedMetadataList.add(timedMetadata);
           }
       }
       ...
   }
   
   private final MediaPlayer.BlackoutsEventListener _blackoutsEventListener =
     new MediaPlayer.BlackoutsEventListener() {
       @Override
       public void onTimedMetadataInBackgroundItem(TimedMetadata timedMetadata) {
           TimedMetadata.Type type = timedMetadata.getType();
           if (type.equals(TimedMetadata.Type.TAG) && _mediaPlayer.getPlaybackRange() != null
               && _mediaPlayer.getPlaybackRange().getDuration() > 0) {
               if (!_timedMetadataList.contains(timedMetadata) && isBlackoutMetadata(timedMetadata)) {
                   _timedMetadataList.add(timedMetadata);
               }
           }
       }
   
       @Override
       public void onBackgroundManifestFailed() {
           ...
       }
   };
   

4. 控點 TimedMetadata 物件，當 MediaPlayer 時間執行。

   _playbackClockEventListener = new Clock.ClockEventListener() {
       @Override
       public void onTick(String name) {
           getActivity().runOnUiThread(new Runnable() {
               @Override
               public void run() {
                   /* handle timedmetadata object list  */
                   if (_mediaPlayer != null && _timedMetadataList != null
                       && _timedMetadataList.size() > 0) {
                       if (_lastKnownStatus == MediaPlayer.PlayerState.PLAYING) {
                           long localTime = _mediaPlayer.getLocalTime();
                           handleTimedMetadataList(localTime);
                       }
                   }
               }
           });
       }
   };
   

5. 建立用於在中斷期間開始和結束時切換內容的方法。

   private void handleTimedMetadataList(long currentTime) {
       for (int i = 0; i < _timedMetadataList.size(); i++) {
           TimedMetadata timedMetadata = _timedMetadataList.get(i);
           long diff = localTime - timedMetadata.getTime();
           if (!_timedMetadataDispatchedList.contains(timedMetadata)
               && diff >= 0
               && diff <= PLAYBACK_CLOCK_INTERVAL
               && _mediaPlayer.shouldTriggerSubscribedTagEvent()) {
                   // switch to blackout content
               if (!_inBlackout && isBlackoutStartTimedMetadata(timedMetadata)) {
                   MediaResource blackoutMediaResource = createBlackoutMediaResource(timedMetadata);
   
                   //1. register current item as background item
                   _mediaPlayer.registerCurrentItemAsBackgroundItem();
   
                   //2. replace current item with blackout item
                   _mediaPlayer.replaceCurrentItem(blackoutMediaResource);
   
                   //3. update qos metrics
                   _mediaQosProvider.updateMetrics(_mediaPlayer);
   
                   //4. maintain state
                   _inBlackout = true;
                   resetTimedMetada();
   
                   break;
               }
               // switch back to main content
               else if (_inBlackout && isBlackoutEndTimedMetadata(timedMetadata)) {
                   //1. register current item as background item
                   _mediaPlayer.unregisterCurrentBackgroundItem();
   
                   //2. replace current item with blackout item
                   _mediaPlayer.replaceCurrentItem(_oldMediaResource);
   
                   //3. update qos metrics
                   _mediaQosProvider.updateMetrics(_mediaPlayer);
   
                   //4. maintain state
                   _inBlackout = false;
                   resetTimedMetada();
   
                   break;
               }
           }
       }
   }
   

6. 如果中斷範圍在播放資料流的DVR中，請更新不可搜尋的範圍。

   // prepare and update blackout nonSeekable ranges
   
   List<TimeRange> blackoutRanges = prepareBlackoutRanges(_timedMetadataList);
   if (blackoutRanges != null && blackoutRanges.size() > 0) {
       int size = blackoutRanges.size();
       TimeRange[] blackoutRangesArray = blackoutRanges.toArray(new TimeRange[size]);
       BlackoutMetadata blackoutMetadata = new BlackoutMetadata(blackoutRangesArray);
       updateBlackoutMetadata(blackoutMetadata);
   }
   
   // function to update blackout metadata
   private void updateBlackoutMetadata(BlackoutMetadata blackoutMetadata) {
       MediaPlayerItem currentItem = _mediaPlayer.getCurrentItem();
       if (currentItem != null) {
           Metadata metadata = currentItem.getResource().getMetadata();
           if (metadata != null) {
               MetadataNode metadataNode = ((MetadataNode) metadata);
               metadataNode.setNode(DefaultMetadataKeys.BLACKOUT_METADATA_KEY.getValue(),
                                    blackoutMetadata);
   
               for (int i = 0; i < blackoutMetadata.getNonSeekableRanges().length; i++) {
                   TimeRange timeRange = blackoutMetadata.getNonSeekableRanges()[i];
               }
           }
       }
   }
   

   注意

   目前對於多個位元速率即時資料流，有時可調整位元速率(ABR)設定檔可能會不同步。 這會導致重複 timedMetadata 相同訂閱標籤的物件。 為了避免不正確的不可搜尋計算，強烈建議您在計算之後檢查是否有重疊的不可搜尋範圍，例如以下範例中：

   List<TimeRange> rangesToRemove = new ArrayList<TimeRange>();
   
   for (int i = 0; i < nonSeekableRanges.size() - 1; i++) {
       TimeRange range1 = nonSeekableRanges.get(i);
       TimeRange range2 = nonSeekableRanges.get(i + 1);
       if (range1.contains(range2.getBegin()) && !rangesToRemove.contains(range2)) {
          rangesToRemove.add(range2);
       } else if (range2.contains(range1.getBegin()) && !rangesToRemove.contains(range1)) {
          rangesToRemove.add(range1);
      }
   }
   
   if (nonSeekableRanges.size() > 0 && rangesToRemove.size() > 0) {
       nonSeekableRanges.removeAll(rangesToRemove);
       for (int i = 0; i < rangesToRemove.size(); i++) {
           TimeRange range = rangesToRemove.get(i);
       }
   }
   
   if (nonSeekableRanges.size() > 0 && rangesToRemove.size() > 0) {
       nonSeekableRanges.removeAll(rangesToRemove);
   }