CompositeSequenceableLoader: Prefer buffered position of A/V tracks

Preferring audio and video tracks matches logic we already have in
[`ProgressiveMediaPeriod.getBufferedPositionUs`](https://github.com/androidx/media/blob/f6fe90f30ba022c7e04e14a3dc5c28c568a4d1e2/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/ProgressiveMediaPeriod.java#L403).

PiperOrigin-RevId: 599154217

Author: icbaker

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/CompositeSequenceableLoader.java

@@ -15,39 +15,80 @@
  */
 package androidx.media3.exoplayer.source;
 
+import static androidx.media3.common.util.Assertions.checkArgument;
 import static java.lang.Math.min;
 
 import androidx.media3.common.C;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.exoplayer.LoadingInfo;
+import com.google.common.collect.ImmutableList;
+import java.util.Collections;
+import java.util.List;
 
 /** A {@link SequenceableLoader} that encapsulates multiple other {@link SequenceableLoader}s. */
 @UnstableApi
 public final class CompositeSequenceableLoader implements SequenceableLoader {
 
-  private final SequenceableLoader[] loaders;
+  private final ImmutableList<SequenceableLoaderWithTrackTypes> loadersWithTrackTypes;
 
+  /**
+   * @deprecated Use {@link CompositeSequenceableLoader#CompositeSequenceableLoader(List, List)}
+   *     instead.
+   */
+  @Deprecated
   public CompositeSequenceableLoader(SequenceableLoader[] loaders) {
-    this.loaders = loaders;
+    this(
+        ImmutableList.copyOf(loaders),
+        Collections.nCopies(loaders.length, ImmutableList.of(C.TRACK_TYPE_UNKNOWN)));
+  }
+
+  public CompositeSequenceableLoader(
+      List<? extends SequenceableLoader> loaders,
+      List<List<@C.TrackType Integer>> loaderTrackTypes) {
+    ImmutableList.Builder<SequenceableLoaderWithTrackTypes> loaderAndTrackTypes =
+        ImmutableList.builder();
+    checkArgument(loaders.size() == loaderTrackTypes.size());
+    for (int i = 0; i < loaders.size(); i++) {
+      loaderAndTrackTypes.add(
+          new SequenceableLoaderWithTrackTypes(loaders.get(i), loaderTrackTypes.get(i)));
+    }
+    this.loadersWithTrackTypes = loaderAndTrackTypes.build();
   }
 
   @Override
   public long getBufferedPositionUs() {
     long bufferedPositionUs = Long.MAX_VALUE;
-    for (SequenceableLoader loader : loaders) {
+    boolean hasAudioVideoTracks = false;
+    long bufferedPositionAudioVideoUs = Long.MAX_VALUE;
+    for (int i = 0; i < loadersWithTrackTypes.size(); i++) {
+      SequenceableLoaderWithTrackTypes loader = loadersWithTrackTypes.get(i);
       long loaderBufferedPositionUs = loader.getBufferedPositionUs();
+      if (loader.getTrackTypes().contains(C.TRACK_TYPE_AUDIO)
+          || loader.getTrackTypes().contains(C.TRACK_TYPE_VIDEO)) {
+        hasAudioVideoTracks = true;
+        if (loaderBufferedPositionUs != C.TIME_END_OF_SOURCE) {
+          bufferedPositionAudioVideoUs =
+              min(bufferedPositionAudioVideoUs, loaderBufferedPositionUs);
+        }
+      }
       if (loaderBufferedPositionUs != C.TIME_END_OF_SOURCE) {
         bufferedPositionUs = min(bufferedPositionUs, loaderBufferedPositionUs);
       }
     }
-    return bufferedPositionUs == Long.MAX_VALUE ? C.TIME_END_OF_SOURCE : bufferedPositionUs;
+    if (hasAudioVideoTracks) {
+      return bufferedPositionAudioVideoUs != Long.MAX_VALUE
+          ? bufferedPositionAudioVideoUs
+          : C.TIME_END_OF_SOURCE;
+    } else {
+      return bufferedPositionUs != Long.MAX_VALUE ? bufferedPositionUs : C.TIME_END_OF_SOURCE;
+    }
   }
 
   @Override
   public long getNextLoadPositionUs() {
     long nextLoadPositionUs = Long.MAX_VALUE;
-    for (SequenceableLoader loader : loaders) {
-      long loaderNextLoadPositionUs = loader.getNextLoadPositionUs();
+    for (int i = 0; i < loadersWithTrackTypes.size(); i++) {
+      long loaderNextLoadPositionUs = loadersWithTrackTypes.get(i).getNextLoadPositionUs();
       if (loaderNextLoadPositionUs != C.TIME_END_OF_SOURCE) {
         nextLoadPositionUs = min(nextLoadPositionUs, loaderNextLoadPositionUs);
       }
@@ -57,8 +98,8 @@ public long getNextLoadPositionUs() {
 
   @Override
   public void reevaluateBuffer(long positionUs) {
-    for (SequenceableLoader loader : loaders) {
-      loader.reevaluateBuffer(positionUs);
+    for (int i = 0; i < loadersWithTrackTypes.size(); i++) {
+      loadersWithTrackTypes.get(i).reevaluateBuffer(positionUs);
     }
   }
 
@@ -72,13 +113,13 @@ public boolean continueLoading(LoadingInfo loadingInfo) {
       if (nextLoadPositionUs == C.TIME_END_OF_SOURCE) {
         break;
       }
-      for (SequenceableLoader loader : loaders) {
-        long loaderNextLoadPositionUs = loader.getNextLoadPositionUs();
+      for (int i = 0; i < loadersWithTrackTypes.size(); i++) {
+        long loaderNextLoadPositionUs = loadersWithTrackTypes.get(i).getNextLoadPositionUs();
         boolean isLoaderBehind =
             loaderNextLoadPositionUs != C.TIME_END_OF_SOURCE
                 && loaderNextLoadPositionUs <= loadingInfo.playbackPositionUs;
         if (loaderNextLoadPositionUs == nextLoadPositionUs || isLoaderBehind) {
-          madeProgressThisIteration |= loader.continueLoading(loadingInfo);
+          madeProgressThisIteration |= loadersWithTrackTypes.get(i).continueLoading(loadingInfo);
         }
       }
       madeProgress |= madeProgressThisIteration;
@@ -88,11 +129,54 @@ public boolean continueLoading(LoadingInfo loadingInfo) {
 
   @Override
   public boolean isLoading() {
-    for (SequenceableLoader loader : loaders) {
-      if (loader.isLoading()) {
+    for (int i = 0; i < loadersWithTrackTypes.size(); i++) {
+      if (loadersWithTrackTypes.get(i).isLoading()) {
         return true;
       }
     }
     return false;
   }
+
+  private static final class SequenceableLoaderWithTrackTypes implements SequenceableLoader {
+
+    private final SequenceableLoader loader;
+    private final ImmutableList<@C.TrackType Integer> trackTypes;
+
+    public SequenceableLoaderWithTrackTypes(
+        SequenceableLoader loader, List<@C.TrackType Integer> trackTypes) {
+      this.loader = loader;
+      this.trackTypes = ImmutableList.copyOf(trackTypes);
+    }
+
+    public ImmutableList<@C.TrackType Integer> getTrackTypes() {
+      return trackTypes;
+    }
+
+    // SequenceableLoader implementation
+
+    @Override
+    public long getBufferedPositionUs() {
+      return loader.getBufferedPositionUs();
+    }
+
+    @Override
+    public long getNextLoadPositionUs() {
+      return loader.getNextLoadPositionUs();
+    }
+
+    @Override
+    public boolean continueLoading(LoadingInfo loadingInfo) {
+      return loader.continueLoading(loadingInfo);
+    }
+
+    @Override
+    public boolean isLoading() {
+      return loader.isLoading();
+    }
+
+    @Override
+    public void reevaluateBuffer(long positionUs) {
+      loader.reevaluateBuffer(positionUs);
+    }
+  }
 }

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/CompositeSequenceableLoaderFactory.java

@@ -15,17 +15,33 @@
  */
 package androidx.media3.exoplayer.source;
 
+import androidx.media3.common.C;
 import androidx.media3.common.util.UnstableApi;
+import java.util.List;
 
 /** A factory to create composite {@link SequenceableLoader}s. */
 @UnstableApi
 public interface CompositeSequenceableLoaderFactory {
 
+  /** Returns an empty composite {@link SequenceableLoader}, with no delegate loaders. */
+  SequenceableLoader empty();
+
+  /**
+   * @deprecated Use {@link #empty()} for an empty composite loader, or {@link #create(List, List)}
+   *     for a non-empty one.
+   */
+  @Deprecated
+  SequenceableLoader createCompositeSequenceableLoader(SequenceableLoader... loaders);
+
   /**
    * Creates a composite {@link SequenceableLoader}.
    *
    * @param loaders The sub-loaders that make up the {@link SequenceableLoader} to be built.
+   * @param loaderTrackTypes The track types handled by each entry in {@code loaders}. Must be the
+   *     same as {@code loaders}.
    * @return A composite {@link SequenceableLoader} that comprises the given loaders.
    */
-  SequenceableLoader createCompositeSequenceableLoader(SequenceableLoader... loaders);
+  SequenceableLoader create(
+      List<? extends SequenceableLoader> loaders,
+      List<List<@C.TrackType Integer>> loaderTrackTypes);
 }

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/DefaultCompositeSequenceableLoaderFactory.java

@@ -15,15 +15,32 @@
  */
 package androidx.media3.exoplayer.source;
 
+import androidx.media3.common.C;
 import androidx.media3.common.util.UnstableApi;
+import com.google.common.collect.ImmutableList;
+import java.util.List;
 
 /** Default implementation of {@link CompositeSequenceableLoaderFactory}. */
 @UnstableApi
 public final class DefaultCompositeSequenceableLoaderFactory
     implements CompositeSequenceableLoaderFactory {
 
   @Override
+  public SequenceableLoader empty() {
+    return new CompositeSequenceableLoader(ImmutableList.of(), ImmutableList.of());
+  }
+
+  @Deprecated
+  @Override
+  @SuppressWarnings("deprecation") // Calling deprecated constructor
   public SequenceableLoader createCompositeSequenceableLoader(SequenceableLoader... loaders) {
     return new CompositeSequenceableLoader(loaders);
   }
+
+  @Override
+  public SequenceableLoader create(
+      List<? extends SequenceableLoader> loaders,
+      List<List<@C.TrackType Integer>> loaderTrackTypes) {
+    return new CompositeSequenceableLoader(loaders, loaderTrackTypes);
+  }
 }

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/MergingMediaPeriod.java

@@ -29,6 +29,7 @@
 import androidx.media3.exoplayer.source.chunk.MediaChunk;
 import androidx.media3.exoplayer.source.chunk.MediaChunkIterator;
 import androidx.media3.exoplayer.trackselection.ExoTrackSelection;
+import com.google.common.collect.Lists;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -58,8 +59,7 @@ public MergingMediaPeriod(
     this.periods = periods;
     childrenPendingPreparation = new ArrayList<>();
     childTrackGroupByMergedTrackGroup = new HashMap<>();
-    compositeSequenceableLoader =
-        compositeSequenceableLoaderFactory.createCompositeSequenceableLoader();
+    compositeSequenceableLoader = compositeSequenceableLoaderFactory.empty();
     streamPeriodIndices = new IdentityHashMap<>();
     enabledPeriods = new MediaPeriod[0];
     for (int i = 0; i < periods.length; i++) {
@@ -172,7 +172,9 @@ public long selectTracks(
     // Update the local state.
     enabledPeriods = enabledPeriodsList.toArray(new MediaPeriod[0]);
     compositeSequenceableLoader =
-        compositeSequenceableLoaderFactory.createCompositeSequenceableLoader(enabledPeriods);
+        compositeSequenceableLoaderFactory.create(
+            enabledPeriodsList,
+            Lists.transform(enabledPeriodsList, period -> period.getTrackGroups().getTrackTypes()));
     return positionUs;
   }
 

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/TrackGroupArray.java

@@ -25,6 +25,7 @@
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
 import java.util.List;
 
 /**
@@ -90,6 +91,11 @@ public boolean isEmpty() {
     return length == 0;
   }
 
+  /** Returns the {@link TrackGroup#type} of each track group in this array. */
+  public ImmutableList<@C.TrackType Integer> getTrackTypes() {
+    return ImmutableList.copyOf(Lists.transform(trackGroups, t -> t.type));
+  }
+
   @Override
   public int hashCode() {
     if (hashCode == 0) {