Refactor #6.5: Restore DASH UTC timing element support.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=121002218

library/src/main/java/com/google/android/exoplayer/dash/DashChunkSource.java

@@ -46,6 +46,8 @@ import com.google.android.exoplayer.upstream.DataSpec;
 import com.google.android.exoplayer.util.MimeTypes;
 import com.google.android.exoplayer.util.Util;
 
+import android.os.SystemClock;
+
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
@@ -62,6 +64,7 @@ public class DashChunkSource implements ChunkSource {
   private final boolean[] adaptiveFormatBlacklistFlags;
   private final DataSource dataSource;
   private final FormatEvaluator adaptiveFormatEvaluator;
+  private final long elapsedRealtimeOffsetUs;
   private final Evaluation evaluation;
 
   private MediaPresentationDescription manifest;
@@ -77,15 +80,19 @@ public class DashChunkSource implements ChunkSource {
    * @param tracks The indices of the selected tracks within the adaptation set.
    * @param dataSource A {@link DataSource} suitable for loading the media data.
    * @param adaptiveFormatEvaluator For adaptive tracks, selects from the available formats.
+   * @param elapsedRealtimeOffsetMs If known, an estimate of the instantaneous difference between
+   *     server-side unix time and {@link SystemClock#elapsedRealtime()} in milliseconds, specified
+   *     as the server's unix time minus the local elapsed time. It unknown, set to 0.
    */
   public DashChunkSource(MediaPresentationDescription manifest, int adaptationSetIndex,
       TrackGroup trackGroup, int[] tracks, DataSource dataSource,
-      FormatEvaluator adaptiveFormatEvaluator) {
+      FormatEvaluator adaptiveFormatEvaluator, long elapsedRealtimeOffsetMs) {
     this.manifest = manifest;
     this.adaptationSetIndex = adaptationSetIndex;
     this.trackGroup = trackGroup;
     this.dataSource = dataSource;
     this.adaptiveFormatEvaluator = adaptiveFormatEvaluator;
+    this.elapsedRealtimeOffsetUs = elapsedRealtimeOffsetMs * 1000;
     this.evaluation = new Evaluation();
 
     Period period = manifest.getPeriod(0);
@@ -197,9 +204,7 @@ public class DashChunkSource implements ChunkSource {
       return;
     }
 
-    // TODO[REFACTOR]: Bring back UTC timing element support.
-    long nowUs = System.currentTimeMillis() * 1000;
-
+    long nowUs = getNowUnixTimeUs();
     int firstAvailableSegmentNum = representationHolder.getFirstSegmentNum();
     int lastAvailableSegmentNum = representationHolder.getLastSegmentNum();
     boolean indexUnbounded = lastAvailableSegmentNum == DashSegmentIndex.INDEX_UNBOUNDED;
@@ -278,6 +283,14 @@ public class DashChunkSource implements ChunkSource {
 
   // Private methods.
 
+  private long getNowUnixTimeUs() {
+    if (elapsedRealtimeOffsetUs != 0) {
+      return (SystemClock.elapsedRealtime() * 1000) + elapsedRealtimeOffsetUs;
+    } else {
+      return System.currentTimeMillis() * 1000;
+    }
+  }
+
   private Chunk newInitializationChunk(RangedUri initializationUri, RangedUri indexUri,
       Representation representation, ChunkExtractorWrapper extractor, DataSource dataSource,
       int trigger) {

library/src/main/java/com/google/android/exoplayer/dash/DashSampleSource.java

@@ -33,17 +33,20 @@ import com.google.android.exoplayer.dash.mpd.MediaPresentationDescription;
 import com.google.android.exoplayer.dash.mpd.MediaPresentationDescriptionParser;
 import com.google.android.exoplayer.dash.mpd.Period;
 import com.google.android.exoplayer.dash.mpd.Representation;
+import com.google.android.exoplayer.dash.mpd.UtcTimingElement;
+import com.google.android.exoplayer.dash.mpd.UtcTimingElementResolver;
+import com.google.android.exoplayer.dash.mpd.UtcTimingElementResolver.UtcTimingCallback;
 import com.google.android.exoplayer.upstream.BandwidthMeter;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DataSourceFactory;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
-import com.google.android.exoplayer.util.Assertions;
 import com.google.android.exoplayer.util.ManifestFetcher;
 import com.google.android.exoplayer.util.Util;
 
 import android.net.Uri;
 import android.os.Handler;
 import android.os.SystemClock;
+import android.util.Log;
 import android.util.Pair;
 
 import java.io.IOException;
@@ -53,7 +56,9 @@ import java.util.List;
 /**
  * A {@link SampleSource} for DASH media.
  */
-public final class DashSampleSource implements SampleSource {
+public final class DashSampleSource implements SampleSource, UtcTimingCallback {
+
+  private static final String TAG = "DashSampleSource";
 
   private final ManifestFetcher<MediaPresentationDescription> manifestFetcher;
   private final DataSourceFactory dataSourceFactory;
@@ -63,8 +68,10 @@ public final class DashSampleSource implements SampleSource {
   private final LoadControl loadControl;
 
   private boolean prepared;
+  private boolean released;
   private long durationUs;
-  private MediaPresentationDescription currentManifest;
+  private long elapsedRealtimeOffset;
+  private MediaPresentationDescription manifest;
   private TrackGroupArray trackGroups;
   private int[] trackGroupAdaptationSetIndices;
   private boolean pendingReset;
@@ -96,20 +103,24 @@ public final class DashSampleSource implements SampleSource {
       return true;
     }
 
-    if (currentManifest == null) {
-      currentManifest = manifestFetcher.getManifest();
-      if (currentManifest == null) {
+    if (manifest == null) {
+      manifest = manifestFetcher.getManifest();
+      if (manifest == null) {
         manifestFetcher.maybeThrowError();
         manifestFetcher.requestRefresh();
         return false;
       }
+      durationUs = manifest.dynamic ? C.UNSET_TIME_US : manifest.duration * 1000;
+      buildTrackGroups(manifest);
+      if (manifest.utcTiming != null) {
+        UtcTimingElementResolver.resolveTimingElement(dataSourceFactory.createDataSource(),
+            manifest.utcTiming, manifestFetcher.getManifestLoadCompleteTimestamp(), this);
+      } else {
+        prepared = true;
+      }
     }
 
-    durationUs = currentManifest.dynamic ? C.UNSET_TIME_US : currentManifest.duration * 1000;
-    buildTrackGroups(currentManifest);
-
-    prepared = true;
-    return true;
+    return prepared;
   }
 
   @Override
@@ -125,8 +136,6 @@ public final class DashSampleSource implements SampleSource {
   @Override
   public TrackStream[] selectTracks(List<TrackStream> oldStreams,
       List<TrackSelection> newSelections, long positionUs) {
-    Assertions.checkState(prepared);
-
     int newEnabledSourceCount = trackStreams.length + newSelections.size() - oldStreams.size();
     DashChunkSource[] newChunkSources = new DashChunkSource[newEnabledSourceCount];
     ChunkTrackStream[] newTrackStreams = new ChunkTrackStream[newEnabledSourceCount];
@@ -161,16 +170,16 @@ public final class DashSampleSource implements SampleSource {
 
   @Override
   public void continueBuffering(long positionUs) {
-    if (currentManifest.dynamic) {
+    if (manifest.dynamic) {
       MediaPresentationDescription newManifest = manifestFetcher.getManifest();
-      if (newManifest != currentManifest) {
-        currentManifest = newManifest;
+      if (newManifest != manifest) {
+        manifest = newManifest;
         for (DashChunkSource chunkSource : chunkSources) {
           chunkSource.updateManifest(newManifest);
         }
       }
 
-      long minUpdatePeriod = currentManifest.minUpdatePeriod;
+      long minUpdatePeriod = manifest.minUpdatePeriod;
       if (minUpdatePeriod == 0) {
         // TODO: This is a temporary hack to avoid constantly refreshing the MPD in cases where
         // minUpdatePeriod is set to 0. In such cases we shouldn't refresh unless there is explicit
@@ -233,6 +242,28 @@ public final class DashSampleSource implements SampleSource {
     for (ChunkTrackStream trackStream : trackStreams) {
       trackStream.release();
     }
+    released = true;
+  }
+
+  // UtcTimingCallback implementation.
+
+  @Override
+  public void onTimestampResolved(UtcTimingElement utcTiming, long elapsedRealtimeOffset) {
+    if (released) {
+      return;
+    }
+    this.elapsedRealtimeOffset = elapsedRealtimeOffset;
+    prepared = true;
+  }
+
+  @Override
+  public void onTimestampError(UtcTimingElement utcTiming, IOException e) {
+    if (released) {
+      return;
+    }
+    Log.e(TAG, "Failed to resolve UtcTiming element [" + utcTiming + "]", e);
+    // Be optimistic and continue in the hope that the device clock is correct.
+    prepared = true;
   }
 
   // Internal methods.
@@ -271,13 +302,14 @@ public final class DashSampleSource implements SampleSource {
     FormatEvaluator adaptiveEvaluator = selectedTracks.length > 1
         ? new AdaptiveEvaluator(bandwidthMeter) : null;
     int adaptationSetIndex = trackGroupAdaptationSetIndices[selection.group];
-    AdaptationSet adaptationSet = currentManifest.getPeriod(0).adaptationSets.get(
+    AdaptationSet adaptationSet = manifest.getPeriod(0).adaptationSets.get(
         adaptationSetIndex);
     int adaptationSetType = adaptationSet.type;
     int bufferSize = Util.getDefaultBufferSize(adaptationSetType);
     DataSource dataSource = dataSourceFactory.createDataSource(bandwidthMeter);
-    DashChunkSource chunkSource = new DashChunkSource(currentManifest, adaptationSetIndex,
-        trackGroups.get(selection.group), selectedTracks, dataSource, adaptiveEvaluator);
+    DashChunkSource chunkSource = new DashChunkSource(manifest, adaptationSetIndex,
+        trackGroups.get(selection.group), selectedTracks, dataSource, adaptiveEvaluator,
+        elapsedRealtimeOffset);
     ChunkTrackStream trackStream = new ChunkTrackStream(chunkSource, loadControl, bufferSize,
         positionUs, eventHandler, eventListener, adaptationSetType);
     return Pair.create(chunkSource, trackStream);

library/src/main/java/com/google/android/exoplayer/smoothstreaming/SmoothStreamingSampleSource.java

@@ -37,7 +37,6 @@ import com.google.android.exoplayer.upstream.BandwidthMeter;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DataSourceFactory;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
-import com.google.android.exoplayer.util.Assertions;
 import com.google.android.exoplayer.util.ManifestFetcher;
 import com.google.android.exoplayer.util.MimeTypes;
 import com.google.android.exoplayer.util.Util;
@@ -67,7 +66,6 @@ public final class SmoothStreamingSampleSource implements SampleSource {
   private final LoadControl loadControl;
   private final ManifestFetcher<SmoothStreamingManifest> manifestFetcher;
 
-  private boolean prepared;
   private long durationUs;
   private SmoothStreamingManifest currentManifest;
   private TrackEncryptionBox[] trackEncryptionBoxes;
@@ -102,22 +100,20 @@ public final class SmoothStreamingSampleSource implements SampleSource {
 
   @Override
   public boolean prepare(long positionUs) throws IOException {
-    if (prepared) {
+    if (currentManifest != null) {
+      // Already prepared.
       return true;
     }
 
+    currentManifest = manifestFetcher.getManifest();
     if (currentManifest == null) {
-      currentManifest = manifestFetcher.getManifest();
-      if (currentManifest == null) {
-        manifestFetcher.maybeThrowError();
-        manifestFetcher.requestRefresh();
-        return false;
-      }
+      manifestFetcher.maybeThrowError();
+      manifestFetcher.requestRefresh();
+      return false;
     }
 
     durationUs = currentManifest.durationUs;
     buildTrackGroups(currentManifest);
-
     ProtectionElement protectionElement = currentManifest.protectionElement;
     if (protectionElement != null) {
       byte[] keyId = getProtectionElementKeyId(protectionElement.data);
@@ -127,8 +123,6 @@ public final class SmoothStreamingSampleSource implements SampleSource {
       drmInitData.put(protectionElement.uuid,
           new SchemeInitData(MimeTypes.VIDEO_MP4, protectionElement.data));
     }
-
-    prepared = true;
     return true;
   }
 
@@ -145,8 +139,6 @@ public final class SmoothStreamingSampleSource implements SampleSource {
   @Override
   public TrackStream[] selectTracks(List<TrackStream> oldStreams,
       List<TrackSelection> newSelections, long positionUs) {
-    Assertions.checkState(prepared);
-
     int newEnabledSourceCount = trackStreams.length + newSelections.size() - oldStreams.size();
     SmoothStreamingChunkSource[] newChunkSources =
         new SmoothStreamingChunkSource[newEnabledSourceCount];