From 9ae5083102d9adc8100828e0726c185c36de8e90 Mon Sep 17 00:00:00 2001
From: tonihei <tonihei@google.com>
Date: Fri, 5 Nov 2021 11:34:33 +0000
Subject: [PATCH] Fix track selection with mixed empty/non-empty overrides

When we have multiple overrides for TrackGroups associated with
one renderer, we need to look at all of them to find the non-empty
one. Empty ones should only be used to remove previously selected
tracks for this group and otherwise be ignored.

Currently this is broken because the first override (no matter if
it's empty or not) is used as the final selection for this renderer.

Issue: google/ExoPlayer#9649

#minor-release

PiperOrigin-RevId: 407792330
---
 .../trackselection/DefaultTrackSelector.java  | 19 +++++++---
 .../DefaultTrackSelectorTest.java             | 37 +++++++++++++++++++
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelector.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelector.java
index dbf4d794cc..256d9dd8ab 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelector.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelector.java
@@ -1561,7 +1561,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
         || params.disabledTrackTypes.contains(rendererType)) {
       return null;
     }
-    // Per TrackGroupArray override
+    // Per TrackGroupArray overrides.
     TrackGroupArray rendererTrackGroups = mappedTrackInfo.getTrackGroups(rendererIndex);
     if (params.hasSelectionOverride(rendererIndex, rendererTrackGroups)) {
       @Nullable
@@ -1572,18 +1572,27 @@ public class DefaultTrackSelector extends MappingTrackSelector {
       return new ExoTrackSelection.Definition(
           rendererTrackGroups.get(override.groupIndex), override.tracks, override.type);
     }
-    // Per TrackGroup override
+    // Per TrackGroup overrides.
     for (int j = 0; j < rendererTrackGroups.length; j++) {
       TrackGroup trackGroup = rendererTrackGroups.get(j);
       @Nullable
       TrackSelectionOverride overrideTracks =
           params.trackSelectionOverrides.getOverride(trackGroup);
       if (overrideTracks != null) {
-        return new ExoTrackSelection.Definition(
-            trackGroup, Ints.toArray(overrideTracks.trackIndexes));
+        if (overrideTracks.trackIndexes.isEmpty()) {
+          // TrackGroup is disabled. Deselect the currentDefinition if applicable. Otherwise ignore.
+          if (currentDefinition != null && currentDefinition.group.equals(trackGroup)) {
+            currentDefinition = null;
+          }
+        } else {
+          // Override current definition with new selection.
+          currentDefinition =
+              new ExoTrackSelection.Definition(
+                  trackGroup, Ints.toArray(overrideTracks.trackIndexes));
+        }
       }
     }
-    return currentDefinition; // No override
+    return currentDefinition;
   }
 
   // Track selection prior to overrides and disabled flags being applied.
diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelectorTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelectorTest.java
index 6a61eea7f3..865686aae0 100644
--- a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelectorTest.java
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelectorTest.java
@@ -206,6 +206,43 @@ public final class DefaultTrackSelectorTest {
         .isEqualTo(new RendererConfiguration[] {DEFAULT, DEFAULT});
   }
 
+  @Test
+  public void selectTrack_withMixedEmptyAndNonEmptyTrackOverrides_appliesNonEmptyOverride()
+      throws Exception {
+    TrackGroup videoGroupHighBitrate =
+        new TrackGroup(VIDEO_FORMAT.buildUpon().setAverageBitrate(1_000_000).build());
+    TrackGroup videoGroupMidBitrate =
+        new TrackGroup(VIDEO_FORMAT.buildUpon().setAverageBitrate(500_000).build());
+    TrackGroup videoGroupLowBitrate =
+        new TrackGroup(VIDEO_FORMAT.buildUpon().setAverageBitrate(100_000).build());
+    trackSelector.setParameters(
+        trackSelector
+            .buildUponParameters()
+            .setTrackSelectionOverrides(
+                new TrackSelectionOverrides.Builder()
+                    .addOverride(
+                        new TrackSelectionOverride(
+                            videoGroupHighBitrate, /* trackIndexes= */ ImmutableList.of()))
+                    .addOverride(
+                        new TrackSelectionOverride(
+                            videoGroupMidBitrate, /* trackIndexes= */ ImmutableList.of(0)))
+                    .addOverride(
+                        new TrackSelectionOverride(
+                            videoGroupLowBitrate, /* trackIndexes= */ ImmutableList.of()))
+                    .build()));
+
+    TrackSelectorResult result =
+        trackSelector.selectTracks(
+            RENDERER_CAPABILITIES,
+            new TrackGroupArray(videoGroupHighBitrate, videoGroupMidBitrate, videoGroupLowBitrate),
+            periodId,
+            TIMELINE);
+
+    assertThat(result.selections)
+        .asList()
+        .containsExactly(new FixedTrackSelection(videoGroupMidBitrate, /* track= */ 0), null);
+  }
+
   /** Tests that an empty override is not applied for a different set of available track groups. */
   @Test
   public void selectTracks_withEmptyTrackOverrideForDifferentTracks_hasNoEffect()