Add workaround for unmatched track indices in trex and tkhd.

Both boxes should contain the same list of track indices. However, if only one
track index in each list does not match, we can just assume that these belong
together.

Issue:#4477

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=203481258

RELEASENOTES.md

@@ -15,6 +15,9 @@
   ([#4403](https://github.com/google/ExoPlayer/issues/4413)).
   ([#4403](https://github.com/google/ExoPlayer/issues/4413)).
 * Add support for multiple audio and video tracks in MPEG-PS streams
 * Add support for multiple audio and video tracks in MPEG-PS streams
   ([#4406](https://github.com/google/ExoPlayer/issues/4406)).
   ([#4406](https://github.com/google/ExoPlayer/issues/4406)).
+* Add workaround for track index mismatches between trex and tkhd boxes in
+  fragmented MP4 files
+  ([#4477](https://github.com/google/ExoPlayer/issues/4477)).
 
 
 ### 2.8.2 ###
 ### 2.8.2 ###
 
 

library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java

@@ -499,7 +499,7 @@ public final class FragmentedMp4Extractor implements Extractor {
       for (int i = 0; i < trackCount; i++) {
       for (int i = 0; i < trackCount; i++) {
         Track track = tracks.valueAt(i);
         Track track = tracks.valueAt(i);
         TrackBundle trackBundle = new TrackBundle(extractorOutput.track(i, track.type));
         TrackBundle trackBundle = new TrackBundle(extractorOutput.track(i, track.type));
-        trackBundle.init(track, defaultSampleValuesArray.get(track.id));
+        trackBundle.init(track, getDefaultSampleValues(defaultSampleValuesArray, track.id));
         trackBundles.put(track.id, trackBundle);
         trackBundles.put(track.id, trackBundle);
         durationUs = Math.max(durationUs, track.durationUs);
         durationUs = Math.max(durationUs, track.durationUs);
       }
       }
@@ -509,11 +509,23 @@ public final class FragmentedMp4Extractor implements Extractor {
       Assertions.checkState(trackBundles.size() == trackCount);
       Assertions.checkState(trackBundles.size() == trackCount);
       for (int i = 0; i < trackCount; i++) {
       for (int i = 0; i < trackCount; i++) {
         Track track = tracks.valueAt(i);
         Track track = tracks.valueAt(i);
-        trackBundles.get(track.id).init(track, defaultSampleValuesArray.get(track.id));
+        trackBundles
+            .get(track.id)
+            .init(track, getDefaultSampleValues(defaultSampleValuesArray, track.id));
       }
       }
     }
     }
   }
   }
 
 
+  private DefaultSampleValues getDefaultSampleValues(
+      SparseArray<DefaultSampleValues> defaultSampleValuesArray, int trackId) {
+    if (defaultSampleValuesArray.size() == 1) {
+      // Ignore track id if there is only one track to cope with non-matching track indices.
+      // See https://github.com/google/ExoPlayer/issues/4477.
+      return defaultSampleValuesArray.valueAt(/* index= */ 0);
+    }
+    return Assertions.checkNotNull(defaultSampleValuesArray.get(trackId));
+  }
+
   private void onMoofContainerAtomRead(ContainerAtom moof) throws ParserException {
   private void onMoofContainerAtomRead(ContainerAtom moof) throws ParserException {
     parseMoof(moof, trackBundles, flags, extendedTypeScratch);
     parseMoof(moof, trackBundles, flags, extendedTypeScratch);
     // If drm init data is sideloaded, we ignore pssh boxes.
     // If drm init data is sideloaded, we ignore pssh boxes.