TrackSelection.Factory clean-up.

We currently have two factory methods where it is completely unclear which one needs
to be overridden.

This change deprecates the old one, adds a Util method to easily map back from the new
to the old behaviour, and updates all implementations of the now deprecated method in
our code.

PiperOrigin-RevId: 224303560

RELEASENOTES.md

@@ -5,10 +5,13 @@
 * Support for playing spherical videos on Daydream.
 * Improve decoder re-use between playbacks. TODO: Write and link a blog post
   here ([#2826](https://github.com/google/ExoPlayer/issues/2826)).
-* Add options for controlling audio track selections to `DefaultTrackSelector`
-  ([#3314](https://github.com/google/ExoPlayer/issues/3314)).
+* Track selection:
+  * Add options for controlling audio track selections to `DefaultTrackSelector`
+    ([#3314](https://github.com/google/ExoPlayer/issues/3314)).
+  * Update `TrackSelection.Factory` interface to support creating all track
+    selections together.
 * Do not retry failed loads whose error is `FileNotFoundException`.
-* Prevent Cea608Decoder from generating Subtitles with null Cues list
+* Prevent Cea608Decoder from generating Subtitles with null Cues list.
 * Caching: Cache data with unknown length by default. The previous flag to opt
   in to this behavior (`DataSpec.FLAG_ALLOW_CACHING_UNKNOWN_LENGTH`) has been
   replaced with an opt out flag (`DataSpec.FLAG_DONT_CACHE_IF_LENGTH_UNKNOWN`).

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

@@ -227,27 +227,6 @@ public class AdaptiveTrackSelection extends BaseTrackSelection {
     }
 
     @Override
-    public AdaptiveTrackSelection createTrackSelection(
-        TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks) {
-      if (this.bandwidthMeter != null) {
-        bandwidthMeter = this.bandwidthMeter;
-      }
-      AdaptiveTrackSelection adaptiveTrackSelection =
-          new AdaptiveTrackSelection(
-              group,
-              tracks,
-              new DefaultBandwidthProvider(bandwidthMeter, bandwidthFraction),
-              minDurationForQualityIncreaseMs,
-              maxDurationForQualityDecreaseMs,
-              minDurationToRetainAfterDiscardMs,
-              bufferedFractionToLiveEdgeForQualityIncrease,
-              minTimeBetweenBufferReevaluationMs,
-              clock);
-      adaptiveTrackSelection.experimental_setTrackBitrateEstimator(trackBitrateEstimator);
-      return adaptiveTrackSelection;
-    }
-
-    @Override
     public @NullableType TrackSelection[] createTrackSelections(
         @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
       TrackSelection[] selections = new TrackSelection[definitions.length];
@@ -259,8 +238,9 @@ public class AdaptiveTrackSelection extends BaseTrackSelection {
           continue;
         }
         if (definition.tracks.length > 1) {
-          selections[i] = createTrackSelection(definition.group, bandwidthMeter, definition.tracks);
-          adaptiveSelection = (AdaptiveTrackSelection) selections[i];
+          adaptiveSelection =
+              createAdaptiveTrackSelection(definition.group, bandwidthMeter, definition.tracks);
+          selections[i] = adaptiveSelection;
         } else {
           selections[i] = new FixedTrackSelection(definition.group, definition.tracks[0]);
           int trackBitrate = definition.group.getFormat(definition.tracks[0]).bitrate;
@@ -274,6 +254,26 @@ public class AdaptiveTrackSelection extends BaseTrackSelection {
       }
       return selections;
     }
+
+    private AdaptiveTrackSelection createAdaptiveTrackSelection(
+        TrackGroup group, BandwidthMeter bandwidthMeter, int[] tracks) {
+      if (this.bandwidthMeter != null) {
+        bandwidthMeter = this.bandwidthMeter;
+      }
+      AdaptiveTrackSelection adaptiveTrackSelection =
+          new AdaptiveTrackSelection(
+              group,
+              tracks,
+              new DefaultBandwidthProvider(bandwidthMeter, bandwidthFraction),
+              minDurationForQualityIncreaseMs,
+              maxDurationForQualityDecreaseMs,
+              minDurationToRetainAfterDiscardMs,
+              bufferedFractionToLiveEdgeForQualityIncrease,
+              minTimeBetweenBufferReevaluationMs,
+              clock);
+      adaptiveTrackSelection.experimental_setTrackBitrateEstimator(trackBitrateEstimator);
+      return adaptiveTrackSelection;
+    }
   }
 
   public static final int DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS = 10000;

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

@@ -24,12 +24,14 @@ import com.google.android.exoplayer2.LoadControl;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
+import com.google.android.exoplayer2.trackselection.TrackSelection.Definition;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.upstream.DefaultAllocator;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Clock;
 import com.google.android.exoplayer2.util.PriorityTaskManager;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Builder for a {@link TrackSelection.Factory} and {@link LoadControl} that implement buffer size
@@ -273,19 +275,22 @@ public final class BufferSizeAdaptationBuilder {
     TrackSelection.Factory trackSelectionFactory =
         new TrackSelection.Factory() {
           @Override
-          public TrackSelection createTrackSelection(
-              TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks) {
-            return new BufferSizeAdaptiveTrackSelection(
-                group,
-                tracks,
-                bandwidthMeter,
-                minBufferMs,
-                maxBufferMs,
-                hysteresisBufferMs,
-                startUpBandwidthFraction,
-                startUpMinBufferForQualityIncreaseMs,
-                dynamicFormatFilter,
-                clock);
+          public @NullableType TrackSelection[] createTrackSelections(
+              @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
+            return TrackSelectionUtil.createTrackSelectionsForDefinitions(
+                definitions,
+                definition ->
+                    new BufferSizeAdaptiveTrackSelection(
+                        definition.group,
+                        definition.tracks,
+                        bandwidthMeter,
+                        minBufferMs,
+                        maxBufferMs,
+                        hysteresisBufferMs,
+                        startUpBandwidthFraction,
+                        startUpMinBufferForQualityIncreaseMs,
+                        dynamicFormatFilter,
+                        clock));
           }
         };
 

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

@@ -21,8 +21,8 @@ import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
-import com.google.android.exoplayer2.util.Assertions;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * A {@link TrackSelection} consisting of a single track.
@@ -56,10 +56,12 @@ public final class FixedTrackSelection extends BaseTrackSelection {
     }
 
     @Override
-    public FixedTrackSelection createTrackSelection(
-        TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks) {
-      Assertions.checkArgument(tracks.length == 1);
-      return new FixedTrackSelection(group, tracks[0], reason, data);
+    public @NullableType TrackSelection[] createTrackSelections(
+        @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      return TrackSelectionUtil.createTrackSelectionsForDefinitions(
+          definitions,
+          definition ->
+              new FixedTrackSelection(definition.group, definition.tracks[0], reason, data));
     }
   }
 

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

@@ -24,6 +24,7 @@ import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import java.util.List;
 import java.util.Random;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * A {@link TrackSelection} whose selected track is updated randomly.
@@ -49,9 +50,11 @@ public final class RandomTrackSelection extends BaseTrackSelection {
     }
 
     @Override
-    public RandomTrackSelection createTrackSelection(
-        TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks) {
-      return new RandomTrackSelection(group, tracks, random);
+    public @NullableType TrackSelection[] createTrackSelections(
+        @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      return TrackSelectionUtil.createTrackSelectionsForDefinitions(
+          definitions,
+          definition -> new RandomTrackSelection(definition.group, definition.tracks, random));
     }
   }
 

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

@@ -21,8 +21,8 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
+import com.google.android.exoplayer2.trackselection.TrackSelectionUtil.AdaptiveTrackSelectionFactory;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
-import com.google.android.exoplayer2.util.Assertions;
 import java.util.List;
 import org.checkerframework.checker.nullness.compatqual.NullableType;
 
@@ -61,42 +61,31 @@ public interface TrackSelection {
   interface Factory {
 
     /**
-     * Creates a new selection.
-     *
-     * @param group The {@link TrackGroup}. Must not be null.
-     * @param bandwidthMeter A {@link BandwidthMeter} which can be used to select tracks.
-     * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
-     *     null or empty. May be in any order.
-     * @return The created selection.
+     * @deprecated Implement {@link #createTrackSelections(Definition[], BandwidthMeter)} instead.
+     *     Calling {@link TrackSelectionUtil#createTrackSelectionsForDefinitions(Definition[],
+     *     AdaptiveTrackSelectionFactory)} helps to create a single adaptive track selection in the
+     *     same way as using this deprecated method.
      */
-    TrackSelection createTrackSelection(
-        TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks);
+    @Deprecated
+    default TrackSelection createTrackSelection(
+        TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks) {
+      throw new UnsupportedOperationException();
+    }
 
     /**
      * Creates a new selection for each {@link Definition}.
      *
      * @param definitions A {@link Definition} array. May include null values.
      * @param bandwidthMeter A {@link BandwidthMeter} which can be used to select tracks.
-     * @return The created selections. For null entries in {@code definitions} returns null values.
+     * @return The created selections. Must have the same length as {@code definitions} and may
+     *     include null values.
      */
+    @SuppressWarnings("deprecation")
     default @NullableType TrackSelection[] createTrackSelections(
         @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
-      TrackSelection[] selections = new TrackSelection[definitions.length];
-      boolean createdAdaptiveTrackSelection = false;
-      for (int i = 0; i < definitions.length; i++) {
-        Definition definition = definitions[i];
-        if (definition == null) {
-          continue;
-        }
-        if (definition.tracks.length > 1) {
-          Assertions.checkState(!createdAdaptiveTrackSelection);
-          createdAdaptiveTrackSelection = true;
-          selections[i] = createTrackSelection(definition.group, bandwidthMeter, definition.tracks);
-        } else {
-          selections[i] = new FixedTrackSelection(definition.group, definition.tracks[0]);
-        }
-      }
-      return selections;
+      return TrackSelectionUtil.createTrackSelectionsForDefinitions(
+          definitions,
+          definition -> createTrackSelection(definition.group, bandwidthMeter, definition.tracks));
     }
   }
 

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

@@ -22,15 +22,59 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.source.chunk.MediaChunkListIterator;
+import com.google.android.exoplayer2.trackselection.TrackSelection.Definition;
 import com.google.android.exoplayer2.util.Assertions;
 import java.util.Arrays;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /** Track selection related utility methods. */
 public final class TrackSelectionUtil {
 
   private TrackSelectionUtil() {}
 
+  /** Functional interface to create a single adaptive track selection. */
+  public interface AdaptiveTrackSelectionFactory {
+
+    /**
+     * Creates an adaptive track selection for the provided track selection definition.
+     *
+     * @param trackSelectionDefinition A {@link Definition} for the track selection.
+     * @return The created track selection.
+     */
+    TrackSelection createAdaptiveTrackSelection(Definition trackSelectionDefinition);
+  }
+
+  /**
+   * Creates track selections for an array of track selection definitions, with at most one
+   * multi-track adaptive selection.
+   *
+   * @param definitions The list of track selection {@link Definition definitions}. May include null
+   *     values.
+   * @param adaptiveTrackSelectionFactory A factory for the multi-track adaptive track selection.
+   * @return The array of created track selection. For null entries in {@code definitions} returns
+   *     null values.
+   */
+  public static @NullableType TrackSelection[] createTrackSelectionsForDefinitions(
+      @NullableType Definition[] definitions,
+      AdaptiveTrackSelectionFactory adaptiveTrackSelectionFactory) {
+    TrackSelection[] selections = new TrackSelection[definitions.length];
+    boolean createdAdaptiveTrackSelection = false;
+    for (int i = 0; i < definitions.length; i++) {
+      Definition definition = definitions[i];
+      if (definition == null) {
+        continue;
+      }
+      if (definition.tracks.length > 1 && !createdAdaptiveTrackSelection) {
+        createdAdaptiveTrackSelection = true;
+        selections[i] = adaptiveTrackSelectionFactory.createAdaptiveTrackSelection(definition);
+      } else {
+        selections[i] = new FixedTrackSelection(definition.group, definition.tracks[0]);
+      }
+    }
+    return selections;
+  }
+
   /**
    * Returns average bitrate for chunks in bits per second. Chunks are included in average until
    * {@code maxDurationMs} or the first unknown length chunk.

library/core/src/test/java/com/google/android/exoplayer2/trackselection/AdaptiveTrackSelectionTest.java

@@ -32,6 +32,7 @@ import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.testutil.FakeClock;
 import com.google.android.exoplayer2.testutil.FakeMediaChunk;
+import com.google.android.exoplayer2.trackselection.TrackSelection.Definition;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.util.MimeTypes;
 import java.util.ArrayList;
@@ -66,15 +67,20 @@ public final class AdaptiveTrackSelectionTest {
   }
 
   @Test
+  @SuppressWarnings("deprecation")
   public void testFactoryUsesInitiallyProvidedBandwidthMeter() {
     BandwidthMeter initialBandwidthMeter = mock(BandwidthMeter.class);
     BandwidthMeter injectedBandwidthMeter = mock(BandwidthMeter.class);
-    Format format = videoFormat(/* bitrate= */ 500, /* width= */ 320, /* height= */ 240);
-    @SuppressWarnings("deprecation")
-    AdaptiveTrackSelection adaptiveTrackSelection =
+    Format format1 = videoFormat(/* bitrate= */ 500, /* width= */ 320, /* height= */ 240);
+    Format format2 = videoFormat(/* bitrate= */ 1000, /* width= */ 640, /* height= */ 480);
+    TrackSelection[] trackSelections =
         new AdaptiveTrackSelection.Factory(initialBandwidthMeter)
-            .createTrackSelection(new TrackGroup(format), injectedBandwidthMeter, /* tracks= */ 0);
-    adaptiveTrackSelection.updateSelectedTrack(
+            .createTrackSelections(
+                new Definition[] {
+                  new Definition(new TrackGroup(format1, format2), /* tracks= */ 0, 1)
+                },
+                injectedBandwidthMeter);
+    trackSelections[0].updateSelectedTrack(
         /* playbackPositionUs= */ 0,
         /* bufferedDurationUs= */ 0,
         /* availableDurationUs= */ C.TIME_UNSET,

testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/FakeTrackSelector.java

@@ -79,8 +79,19 @@ public class FakeTrackSelector extends DefaultTrackSelector {
     }
 
     @Override
-    public TrackSelection createTrackSelection(
-        TrackGroup trackGroup, BandwidthMeter bandwidthMeter, int... tracks) {
+    public TrackSelection[] createTrackSelections(
+        TrackSelection.Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      TrackSelection[] selections = new TrackSelection[definitions.length];
+      for (int i = 0; i < definitions.length; i++) {
+        TrackSelection.Definition definition = definitions[i];
+        if (definition != null) {
+          selections[i] = createTrackSelection(definition.group);
+        }
+      }
+      return selections;
+    }
+
+    private TrackSelection createTrackSelection(TrackGroup trackGroup) {
       if (mayReuseTrackSelection) {
         for (FakeTrackSelection trackSelection : trackSelections) {
           if (trackSelection.getTrackGroup().equals(trackGroup)) {
@@ -92,18 +103,5 @@ public class FakeTrackSelector extends DefaultTrackSelector {
       trackSelections.add(trackSelection);
       return trackSelection;
     }
-
-    @Override
-    public TrackSelection[] createTrackSelections(
-        TrackSelection.Definition[] definitions, BandwidthMeter bandwidthMeter) {
-      TrackSelection[] selections = new TrackSelection[definitions.length];
-      for (int i = 0; i < definitions.length; i++) {
-        TrackSelection.Definition definition = definitions[i];
-        if (definition != null) {
-          selections[i] = createTrackSelection(definition.group, bandwidthMeter, definition.tracks);
-        }
-      }
-      return selections;
-    }
   }
 }