Allow multiple metadata tracks, assuming multiple metadata renderers

library/core/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java

@@ -1732,6 +1732,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
 
     TextTrackScore selectedTextTrackScore = null;
     int selectedTextRendererIndex = C.INDEX_UNSET;
+    int nIgnore = 0;
     for (int i = 0; i < rendererCount; i++) {
       int trackType = mappedTrackInfo.getRendererType(i);
       switch (trackType) {
@@ -1762,7 +1763,8 @@ public class DefaultTrackSelector extends MappingTrackSelector {
         default:
           definitions[i] =
               selectOtherTrack(
-                  trackType, mappedTrackInfo.getTrackGroups(i), rendererFormatSupports[i], params);
+                  trackType, mappedTrackInfo.getTrackGroups(i), rendererFormatSupports[i], params, nIgnore);
+          nIgnore++;
           break;
       }
     }
@@ -2297,11 +2299,12 @@ public class DefaultTrackSelector extends MappingTrackSelector {
    */
   @Nullable
   protected TrackSelection.Definition selectOtherTrack(
-      int trackType, TrackGroupArray groups, int[][] formatSupport, Parameters params)
+      int trackType, TrackGroupArray groups, int[][] formatSupport, Parameters params, int nIgnore)
       throws ExoPlaybackException {
     TrackGroup selectedGroup = null;
     int selectedTrackIndex = 0;
     int selectedTrackScore = 0;
+    int nAlreadyIgnored = 0;
     for (int groupIndex = 0; groupIndex < groups.length; groupIndex++) {
       TrackGroup trackGroup = groups.get(groupIndex);
       int[] trackFormatSupport = formatSupport[groupIndex];
@@ -2315,9 +2318,16 @@ public class DefaultTrackSelector extends MappingTrackSelector {
             trackScore += WITHIN_RENDERER_CAPABILITIES_BONUS;
           }
           if (trackScore > selectedTrackScore) {
-            selectedGroup = trackGroup;
             selectedTrackIndex = trackIndex;
             selectedTrackScore = trackScore;
+            nAlreadyIgnored = 0;
+          }
+          if(trackScore == selectedTrackScore) {
+            if(nAlreadyIgnored == nIgnore) {
+              selectedGroup = trackGroup;
+              selectedTrackIndex = trackIndex;
+            }
+            nAlreadyIgnored++;
           }
         }
       }

library/core/src/main/java/com/google/android/exoplayer2/trackselection/MappingTrackSelector.java

@@ -31,7 +31,10 @@ import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
+
 import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
@@ -356,15 +359,17 @@ public abstract class MappingTrackSelector extends TrackSelector {
     for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
       TrackGroup group = trackGroups.get(groupIndex);
       // Associate the group to a preferred renderer.
-      int rendererIndex = findRenderer(rendererCapabilities, group);
-      // Evaluate the support that the renderer provides for each track in the group.
-      int[] rendererFormatSupport = rendererIndex == rendererCapabilities.length
-          ? new int[group.length] : getFormatSupport(rendererCapabilities[rendererIndex], group);
-      // Stash the results.
-      int rendererTrackGroupCount = rendererTrackGroupCounts[rendererIndex];
-      rendererTrackGroups[rendererIndex][rendererTrackGroupCount] = group;
-      rendererFormatSupports[rendererIndex][rendererTrackGroupCount] = rendererFormatSupport;
-      rendererTrackGroupCounts[rendererIndex]++;
+      List<Integer> rendererIndexes = findAllRenderers(rendererCapabilities, group);
+      for(int rendererIndex: rendererIndexes) {
+        // Evaluate the support that the renderer provides for each track in the group.
+        int[] rendererFormatSupport = rendererIndex == rendererCapabilities.length
+                ? new int[group.length] : getFormatSupport(rendererCapabilities[rendererIndex], group);
+        // Stash the results.
+        int rendererTrackGroupCount = rendererTrackGroupCounts[rendererIndex];
+        rendererTrackGroups[rendererIndex][rendererTrackGroupCount] = group;
+        rendererFormatSupports[rendererIndex][rendererTrackGroupCount] = rendererFormatSupport;
+        rendererTrackGroupCounts[rendererIndex]++;
+      }
     }
 
     // Create a track group array for each renderer, and trim each rendererFormatSupports entry.
@@ -465,6 +470,27 @@ public abstract class MappingTrackSelector extends TrackSelector {
     return bestRendererIndex;
   }
 
+  private static List<Integer> findAllRenderers(RendererCapabilities[] rendererCapabilities, TrackGroup group)
+          throws ExoPlaybackException {
+    ArrayList<Integer> result = new ArrayList<>();
+    int bestFormatSupportLevel = RendererCapabilities.FORMAT_UNSUPPORTED_TYPE;
+    for (int rendererIndex = 0; rendererIndex < rendererCapabilities.length; rendererIndex++) {
+      RendererCapabilities rendererCapability = rendererCapabilities[rendererIndex];
+      for (int trackIndex = 0; trackIndex < group.length; trackIndex++) {
+        int formatSupportLevel = rendererCapability.supportsFormat(group.getFormat(trackIndex))
+                & RendererCapabilities.FORMAT_SUPPORT_MASK;
+        if (formatSupportLevel > bestFormatSupportLevel) {
+          bestFormatSupportLevel = formatSupportLevel;
+          result.clear();
+        }
+        if (formatSupportLevel == bestFormatSupportLevel) {
+          result.add(rendererIndex);
+        }
+      }
+    }
+    return result;
+  }
+
   /**
    * Calls {@link RendererCapabilities#supportsFormat} for each track in the specified
    * {@link TrackGroup}, returning the results in an array.