Add workaround for unmatched track indices in tkhd and tfhd.

If there is only one track, we can assume that both boxes refer to the same track
even if the track indices don't match.

Issue:#4083

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=203485872

RELEASENOTES.md

@@ -18,6 +18,9 @@
 * Add workaround for track index mismatches between trex and tkhd boxes in
   fragmented MP4 files
   ([#4477](https://github.com/google/ExoPlayer/issues/4477)).
+* Add workaround for track index mismatches between tfhd and tkhd boxes in
+  fragmented MP4 files
+  ([#4083](https://github.com/google/ExoPlayer/issues/4083)).
 
 ### 2.8.2 ###
 

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

@@ -654,7 +654,7 @@ private static void parseMoof(ContainerAtom moof, SparseArray<TrackBundle> track
   private static void parseTraf(ContainerAtom traf, SparseArray<TrackBundle> trackBundleArray,
       @Flags int flags, byte[] extendedTypeScratch) throws ParserException {
     LeafAtom tfhd = traf.getLeafAtomOfType(Atom.TYPE_tfhd);
-    TrackBundle trackBundle = parseTfhd(tfhd.data, trackBundleArray, flags);
+    TrackBundle trackBundle = parseTfhd(tfhd.data, trackBundleArray);
     if (trackBundle == null) {
       return;
     }
@@ -805,13 +805,13 @@ private static void parseSaio(ParsableByteArray saio, TrackFragment out) throws
    * @return The {@link TrackBundle} to which the {@link TrackFragment} belongs, or null if the tfhd
    *     does not refer to any {@link TrackBundle}.
    */
-  private static TrackBundle parseTfhd(ParsableByteArray tfhd,
-      SparseArray<TrackBundle> trackBundles, int flags) {
+  private static TrackBundle parseTfhd(
+      ParsableByteArray tfhd, SparseArray<TrackBundle> trackBundles) {
     tfhd.setPosition(Atom.HEADER_SIZE);
     int fullAtom = tfhd.readInt();
     int atomFlags = Atom.parseFullAtomFlags(fullAtom);
     int trackId = tfhd.readInt();
-    TrackBundle trackBundle = trackBundles.get((flags & FLAG_SIDELOADED) == 0 ? trackId : 0);
+    TrackBundle trackBundle = getTrackBundle(trackBundles, trackId);
     if (trackBundle == null) {
       return null;
     }
@@ -836,6 +836,17 @@ private static TrackBundle parseTfhd(ParsableByteArray tfhd,
     return trackBundle;
   }
 
+  private static @Nullable TrackBundle getTrackBundle(
+      SparseArray<TrackBundle> trackBundles, int trackId) {
+    if (trackBundles.size() == 1) {
+      // Ignore track id if there is only one track. This is either because we have a side-loaded
+      // track (flag FLAG_SIDELOADED) or to cope with non-matching track indices (see
+      // https://github.com/google/ExoPlayer/issues/4083).
+      return trackBundles.valueAt(/* index= */ 0);
+    }
+    return trackBundles.get(trackId);
+  }
+
   /**
    * Parses a tfdt atom (defined in 14496-12).
    *