Offset SIDX timestamps by presentationTimeOffset

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=199856613

RELEASENOTES.md

@@ -4,6 +4,8 @@
 
 * IMA: Don't advertise support for video/mpeg ad media, as we don't have an
   extractor for this ([#4297](https://github.com/google/ExoPlayer/issues/4297)).
+* DASH: Fix playback getting stuck when playing representations that have both
+  sidx atoms and non-zero presentationTimeOffset values.
 * Mitigate memory leaks when `MediaSource` loads are slow to cancel
   ([#4249](https://github.com/google/ExoPlayer/issues/4249)).
 * Fix inconsistent `Player.EventListener` invocations for recursive player state

library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashWrappingSegmentIndex.java

@@ -25,12 +25,15 @@
 public final class DashWrappingSegmentIndex implements DashSegmentIndex {
 
   private final ChunkIndex chunkIndex;
+  private final long timeOffsetUs;
 
   /**
    * @param chunkIndex The {@link ChunkIndex} to wrap.
+   * @param timeOffsetUs An offset to subtract from the times in the wrapped index, in microseconds.
    */
-  public DashWrappingSegmentIndex(ChunkIndex chunkIndex) {
+  public DashWrappingSegmentIndex(ChunkIndex chunkIndex, long timeOffsetUs) {
     this.chunkIndex = chunkIndex;
+    this.timeOffsetUs = timeOffsetUs;
   }
 
   @Override
@@ -45,7 +48,7 @@ public int getSegmentCount(long periodDurationUs) {
 
   @Override
   public long getTimeUs(long segmentNum) {
-    return chunkIndex.timesUs[(int) segmentNum];
+    return chunkIndex.timesUs[(int) segmentNum] - timeOffsetUs;
   }
 
   @Override
@@ -61,7 +64,7 @@ public RangedUri getSegmentUrl(long segmentNum) {
 
   @Override
   public long getSegmentNum(long timeUs, long periodDurationUs) {
-    return chunkIndex.getChunkIndex(timeUs);
+    return chunkIndex.getChunkIndex(timeUs + timeOffsetUs);
   }
 
   @Override

library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DefaultDashChunkSource.java

@@ -354,7 +354,10 @@ public void onChunkLoadCompleted(Chunk chunk) {
       if (representationHolder.segmentIndex == null) {
         SeekMap seekMap = representationHolder.extractorWrapper.getSeekMap();
         if (seekMap != null) {
-          representationHolder.segmentIndex = new DashWrappingSegmentIndex((ChunkIndex) seekMap);
+          representationHolder.segmentIndex =
+              new DashWrappingSegmentIndex(
+                  (ChunkIndex) seekMap,
+                  representationHolder.representation.presentationTimeOffsetUs);
         }
       }
     }

library/dash/src/main/java/com/google/android/exoplayer2/source/dash/offline/DashDownloader.java

@@ -167,7 +167,9 @@ private static void addSegment(
       return index;
     }
     ChunkIndex seekMap = DashUtil.loadChunkIndex(dataSource, trackType, representation);
-    return seekMap == null ? null : new DashWrappingSegmentIndex(seekMap);
+    return seekMap == null
+        ? null
+        : new DashWrappingSegmentIndex(seekMap, representation.presentationTimeOffsetUs);
   }
 
 }