Converge track selection to a single place.

This change merges the duties of FormatEvaluator into TrackSelection classes, so that both the static and dynamic parts of track selection are implemented in a single place. New feature: Demo app now allows you to enable random adaptation in the track selection dialog. Notes: - It should be quite easy to allow application side track blacklisting in addition to source side, as an extension to this. That would effectively allow applications to do seamless/deferred track selection by creating a TrackSelection with all tracks enabled, and then toggling the blacklist flags to select the ones they want to be active. - It should be trivial to implement format blacklisting for DASH and SS as an extension to this. Will do in a follow up CL. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=128707517

Converge track selection to a single place.
This change merges the duties of FormatEvaluator into TrackSelection classes, so that both the static and dynamic parts of track selection are implemented in a single place. New feature: Demo app now allows you to enable random adaptation in the track selection dialog. Notes: - It should be quite easy to allow application side track blacklisting in addition to source side, as an extension to this. That would effectively allow applications to do seamless/deferred track selection by creating a TrackSelection with all tracks enabled, and then toggling the blacklist flags to select the ones they want to be active. - It should be trivial to implement format blacklisting for DASH and SS as an extension to this. Will do in a follow up CL. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=128707517
3501332d · olly · Oliver Woodman · 5eb61906 · 3501332d · 3501332d
Commit 3501332d authored Jul 28, 2016 by olly Committed by Oliver Woodman Jul 28, 2016
Showing with 712 additions and 360 deletions
demo/src/main/java/com/google/android/exoplayer2/demo/EventLogger.java
demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java
demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
demo/src/main/res/values/strings.xml
library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
library/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java
library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSource.java
library/src/main/java/com/google/android/exoplayer2/source/chunk/FormatEvaluator.java
library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaPeriod.java
library/src/main/java/com/google/android/exoplayer2/source/dash/DefaultDashChunkSource.java
library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
library/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
library/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java
library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/DefaultSsChunkSource.java
library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaPeriod.java
library/src/main/java/com/google/android/exoplayer2/trackselection/AdaptiveVideoTrackSelection.java
library/src/main/java/com/google/android/exoplayer2/trackselection/BaseTrackSelection.java
library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
--- a/demo/src/main/java/com/google/android/exoplayer2/demo/EventLogger.java
+++ b/demo/src/main/java/com/google/android/exoplayer2/demo/EventLogger.java
@@ -364,15 +364,8 @@ public class EventLogger implements ExoPlayer.EventListener, SimpleExoPlayer.Deb
  private static String getTrackStatusString(TrackSelection selection, TrackGroup group,
      int trackIndex) {
-    boolean groupEnabled = selection != null && selection.group == group;
+    return getTrackStatusString(selection != null && selection.getTrackGroup() == group
-    if (groupEnabled) {
+        && selection.indexOf(trackIndex) != -1);
-      for (int i = 0; i < selection.length; i++) {
-        if (selection.getTrack(i) == trackIndex) {
-          return getTrackStatusString(true);
-        }
-      }
-    }
-    return getTrackStatusString(false);
  }
  private static String getTrackStatusString(boolean enabled) {

--- a/demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java
+++ b/demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java
@@ -39,8 +39,6 @@ import com.google.android.exoplayer2.source.ExtractorMediaSource;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.Timeline;
 import com.google.android.exoplayer2.source.TrackGroupArray;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator.AdaptiveEvaluator;
 import com.google.android.exoplayer2.source.dash.DashMediaSource;
 import com.google.android.exoplayer2.source.dash.DefaultDashChunkSource;
 import com.google.android.exoplayer2.source.hls.HlsMediaSource;
@@ -48,13 +46,15 @@ import com.google.android.exoplayer2.source.smoothstreaming.DefaultSsChunkSource
 import com.google.android.exoplayer2.source.smoothstreaming.SsMediaSource;
 import com.google.android.exoplayer2.text.CaptionStyleCompat;
 import com.google.android.exoplayer2.text.Cue;
-import com.google.android.exoplayer2.ui.SubtitleView;
+import com.google.android.exoplayer2.trackselection.AdaptiveVideoTrackSelection;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector.TrackInfo;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.ui.AspectRatioFrameLayout;
 import com.google.android.exoplayer2.ui.DebugTextViewHelper;
 import com.google.android.exoplayer2.ui.PlayerControl;
+import com.google.android.exoplayer2.ui.SubtitleView;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
 import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
@@ -138,7 +138,7 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback, 
  private String userAgent;
  private DataSource.Factory manifestDataSourceFactory;
  private DataSource.Factory mediaDataSourceFactory;
-  private FormatEvaluator.Factory formatEvaluatorFactory;
+  private DefaultBandwidthMeter bandwidthMeter;
  private SimpleExoPlayer player;
  private MappingTrackSelector trackSelector;
  private TrackSelectionHelper trackSelectionHelper;
@@ -155,9 +155,8 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback, 
    super.onCreate(savedInstanceState);
    userAgent = Util.getUserAgent(this, "ExoPlayerDemo");
    manifestDataSourceFactory = new DefaultDataSourceFactory(this, userAgent);
-    DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
+    bandwidthMeter = new DefaultBandwidthMeter();
    mediaDataSourceFactory = new DefaultDataSourceFactory(this, userAgent, bandwidthMeter);
-    formatEvaluatorFactory = new AdaptiveEvaluator.Factory(bandwidthMeter);
    mainHandler = new Handler();
    setContentView(R.layout.player_activity);
@@ -284,12 +283,15 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback, 
          return;
        }
      }
      eventLogger = new EventLogger();
      eventLogger.startSession();
-      trackSelector = new DefaultTrackSelector(mainHandler);
+      TrackSelection.Factory videoTrackSelectionFactory =
+          new AdaptiveVideoTrackSelection.Factory(bandwidthMeter);
+      trackSelector = new DefaultTrackSelector(mainHandler, videoTrackSelectionFactory);
      trackSelector.addListener(this);
      trackSelector.addListener(eventLogger);
-      trackSelectionHelper = new TrackSelectionHelper(trackSelector);
+      trackSelectionHelper = new TrackSelectionHelper(trackSelector, videoTrackSelectionFactory);
      player = ExoPlayerFactory.newSimpleInstance(this, trackSelector, new DefaultLoadControl(),
          drmSessionManager, preferExtensionDecoders);
      player.addListener(this);
@@ -354,15 +356,14 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback, 
    switch (type) {
      case Util.TYPE_SS:
        DefaultSsChunkSource.Factory factory = new DefaultSsChunkSource.Factory(
-            mediaDataSourceFactory, formatEvaluatorFactory);
+            mediaDataSourceFactory);
        return new SsMediaSource(uri, manifestDataSourceFactory, factory, mainHandler, eventLogger);
      case Util.TYPE_DASH:
        DefaultDashChunkSource.Factory factory2 = new DefaultDashChunkSource.Factory(
-            mediaDataSourceFactory, formatEvaluatorFactory);
+            mediaDataSourceFactory);
        return new DashMediaSource(uri, mediaDataSourceFactory, factory2, mainHandler, eventLogger);
      case Util.TYPE_HLS:
-        return new HlsMediaSource(uri, mediaDataSourceFactory, formatEvaluatorFactory, mainHandler,
+        return new HlsMediaSource(uri, mediaDataSourceFactory, mainHandler, eventLogger);
-            eventLogger);
      case Util.TYPE_OTHER:
        return new ExtractorMediaSource(uri, mediaDataSourceFactory, new DefaultExtractorsFactory(),
            mainHandler, eventLogger);

--- a/demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
+++ b/demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
@@ -19,8 +19,10 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.RendererCapabilities;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
+import com.google.android.exoplayer2.trackselection.FixedTrackSelection;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector.TrackInfo;
+import com.google.android.exoplayer2.trackselection.RandomTrackSelection;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.util.MimeTypes;
@@ -45,6 +47,7 @@ import java.util.Locale;
    DialogInterface.OnClickListener {
  private final MappingTrackSelector selector;
+  private final TrackSelection.Factory adaptiveVideoTrackSelectionFactory;
  private TrackInfo trackInfo;
  private int rendererIndex;
@@ -55,13 +58,18 @@ import java.util.Locale;
  private CheckedTextView disableView;
  private CheckedTextView defaultView;
+  private CheckedTextView enableRandomAdaptationView;
  private CheckedTextView[][] trackViews;
  /**
   * @param selector The track selector.
+   * @param adaptiveVideoTrackSelectionFactory A factory for adaptive video {@link TrackSelection}s,
+   *     or null if the selection helper should not support adaptive video.
   */
-  public TrackSelectionHelper(MappingTrackSelector selector) {
+  public TrackSelectionHelper(MappingTrackSelector selector,
+      TrackSelection.Factory adaptiveVideoTrackSelectionFactory) {
    this.selector = selector;
+    this.adaptiveVideoTrackSelectionFactory = adaptiveVideoTrackSelectionFactory;
  }
  /**
@@ -80,8 +88,9 @@ import java.util.Locale;
    trackGroups = trackInfo.getTrackGroups(rendererIndex);
    trackGroupsAdaptive = new boolean[trackGroups.length];
    for (int i = 0; i < trackGroups.length; i++) {
-      trackGroupsAdaptive[i] = trackInfo.getAdaptiveSupport(rendererIndex, i, false)
+      trackGroupsAdaptive[i] = adaptiveVideoTrackSelectionFactory != null
-          != RendererCapabilities.ADAPTIVE_NOT_SUPPORTED;
+          && (trackInfo.getAdaptiveSupport(rendererIndex, i, false)
+          != RendererCapabilities.ADAPTIVE_NOT_SUPPORTED);
    }
    isDisabled = selector.getRendererDisabled(rendererIndex);
    override = selector.hasSelectionOverride(rendererIndex, trackGroups)
@@ -118,17 +127,19 @@ import java.util.Locale;
    // Per-track views.
    boolean haveSupportedTracks = false;
+    boolean haveAdaptiveTracks = false;
    trackViews = new CheckedTextView[trackGroups.length][];
    for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
      TrackGroup group = trackGroups.get(groupIndex);
+      boolean groupIsAdaptive = group.length > 1 && trackGroupsAdaptive[groupIndex];
+      haveAdaptiveTracks |= groupIsAdaptive;
      trackViews[groupIndex] = new CheckedTextView[group.length];
      for (int trackIndex = 0; trackIndex < group.length; trackIndex++) {
        if (trackIndex == 0) {
          root.addView(inflater.inflate(R.layout.list_divider, root, false));
        }
-        int trackViewLayoutId = group.length < 2 || !trackGroupsAdaptive[groupIndex]
+        int trackViewLayoutId = groupIsAdaptive ? android.R.layout.simple_list_item_multiple_choice
-            ? android.R.layout.simple_list_item_single_choice
+            : android.R.layout.simple_list_item_single_choice;
-            : android.R.layout.simple_list_item_multiple_choice;
        CheckedTextView trackView = (CheckedTextView) inflater.inflate(
            trackViewLayoutId, root, false);
        trackView.setText(buildTrackName(group.getFormat(trackIndex)));
@@ -148,6 +159,14 @@ import java.util.Locale;
    if (!haveSupportedTracks) {
      // Indicate that the default selection will be nothing.
      defaultView.setText(R.string.selection_default_none);
+    } else if (haveAdaptiveTracks) {
+      // View for using random adaptation.
+      enableRandomAdaptationView = (CheckedTextView) inflater.inflate(
+          android.R.layout.simple_list_item_multiple_choice, root, false);
+      enableRandomAdaptationView.setText(R.string.enable_random_adaptation);
+      enableRandomAdaptationView.setOnClickListener(this);
+      root.addView(inflater.inflate(R.layout.list_divider, root, false));
+      root.addView(enableRandomAdaptationView);
    }
    updateViews();
@@ -158,9 +177,18 @@ import java.util.Locale;
    disableView.setChecked(isDisabled);
    defaultView.setChecked(!isDisabled && override == null);
    for (int i = 0; i < trackViews.length; i++) {
+      TrackGroup trackGroup = trackGroups.get(i);
      for (int j = 0; j < trackViews[i].length; j++) {
-        trackViews[i][j].setChecked(
+        trackViews[i][j].setChecked(override != null && override.getTrackGroup() == trackGroup
-            override != null && override.group == trackGroups.get(i) && override.indexOf(j) != -1);
+            && override.indexOf(trackGroup.getFormat(j)) != -1);
+      }
+    }
+    if (enableRandomAdaptationView != null) {
+      enableRandomAdaptationView.setEnabled(!isDisabled && override != null
+          && override.length() > 1);
+      if (enableRandomAdaptationView.isEnabled()) {
+        enableRandomAdaptationView.setChecked(!isDisabled
+            && override instanceof RandomTrackSelection);
      }
    }
  }
@@ -191,6 +219,9 @@ import java.util.Locale;
    } else if (view == defaultView) {
      isDisabled = false;
      override = null;
+    } else if (view == enableRandomAdaptationView) {
+      setOverride(override.getTrackGroup(), getTracks(override),
+          !enableRandomAdaptationView.isChecked());
    } else {
      isDisabled = false;
      @SuppressWarnings("unchecked")
@@ -198,31 +229,25 @@ import java.util.Locale;
      TrackGroup group = tag.first;
      int trackIndex = tag.second;
      if (!trackGroupsAdaptive[trackGroups.indexOf(group)] || override == null) {
-        override = new TrackSelection(group, trackIndex);
+        override = new FixedTrackSelection(group, trackIndex);
      } else {
        // The group being modified is adaptive and we already have a non-null override.
        boolean isEnabled = ((CheckedTextView) view).isChecked();
+        int overrideLength = override.length();
        if (isEnabled) {
          // Remove the track from the override.
-          if (override.length == 1) {
+          if (overrideLength == 1) {
            // The last track is being removed, so the override becomes empty.
            override = null;
            isDisabled = true;
          } else {
-            int[] tracks = new int[override.length - 1];
+            setOverride(group, getTracksRemoving(override, trackIndex),
-            int trackCount = 0;
+                enableRandomAdaptationView.isChecked());
-            for (int i = 0; i < override.length; i++) {
-              if (override.getTrack(i) != trackIndex) {
-                tracks[trackCount++] = override.getTrack(i);
-              }
-            }
-            override = new TrackSelection(group, tracks);
          }
        } else {
          // Add the track to the override.
-          int[] tracks = Arrays.copyOf(override.getTracks(), override.length + 1);
+          setOverride(group, getTracksAdding(override, trackIndex),
-          tracks[tracks.length - 1] = trackIndex;
+              enableRandomAdaptationView.isChecked());
-          override = new TrackSelection(group, tracks);
        }
      }
    }
@@ -230,6 +255,41 @@ import java.util.Locale;
    updateViews();
  }
+  private void setOverride(TrackGroup group, int[] tracks, boolean enableRandomAdaptation) {
+    override = tracks.length == 1 ? new FixedTrackSelection(group, tracks[0])
+        : (enableRandomAdaptation ? new RandomTrackSelection(group, tracks)
+            : adaptiveVideoTrackSelectionFactory.createTrackSelection(group, tracks));
+  }
+  // Track array manipulation.
+  private static int[] getTracks(TrackSelection trackSelection) {
+    int[] tracks = new int[trackSelection.length()];
+    for (int i = 0; i < tracks.length; i++) {
+      tracks[i] = trackSelection.getIndexInTrackGroup(i);
+    }
+    return tracks;
+  }
+  private static int[] getTracksAdding(TrackSelection trackSelection, int addedTrack) {
+    int[] tracks = getTracks(trackSelection);
+    tracks = Arrays.copyOf(tracks, tracks.length + 1);
+    tracks[tracks.length - 1] = addedTrack;
+    return tracks;
+  }
+  private static int[] getTracksRemoving(TrackSelection trackSelection, int removedTrack) {
+    int[] tracks = new int[trackSelection.length() - 1];
+    int trackCount = 0;
+    for (int i = 0; i < tracks.length + 1; i++) {
+      int track = trackSelection.getIndexInTrackGroup(i);
+      if (track != removedTrack) {
+        tracks[trackCount++] = track;
+      }
+    }
+    return tracks;
+  }
  // Track name construction.
  private static String buildTrackName(Format format) {

--- a/demo/src/main/res/values/strings.xml
+++ b/demo/src/main/res/values/strings.xml
@@ -33,6 +33,8 @@
  <string name="selection_default_none">Default (none)</string>
+  <string name="enable_random_adaptation">Enable random adaptation</string>
  <string name="error_drm_not_supported">Protected content not supported on API levels below 18</string>
  <string name="error_drm_unsupported_scheme">This device does not support the required DRM scheme</string>

--- a/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
+++ b/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
@@ -834,9 +834,9 @@ import java.util.ArrayList;
            if (newSelection != null) {
              // Replace the renderer's SampleStream so the transition to playing the next period
              // can be seamless.
-              Format[] formats = new Format[newSelection.length];
+              Format[] formats = new Format[newSelection.length()];
              for (int j = 0; j < formats.length; j++) {
-                formats[j] = newSelection.group.getFormat(newSelection.getTrack(j));
+                formats[j] = newSelection.getFormat(j);
              }
              renderer.replaceStream(formats, readingPeriod.sampleStreams[i],
                  readingPeriod.offsetUs);
@@ -1087,9 +1087,9 @@ import java.util.ArrayList;
            // Consider as joining only if the renderer was previously disabled.
            boolean joining = !rendererWasEnabledFlags[i] && playing;
            // Build an array of formats contained by the selection.
-            Format[] formats = new Format[newSelection.length];
+            Format[] formats = new Format[newSelection.length()];
            for (int j = 0; j < formats.length; j++) {
-              formats[j] = newSelection.group.getFormat(newSelection.getTrack(j));
+              formats[j] = newSelection.getFormat(j);
            }
            // Enable the renderer.
            renderer.enable(formats, playingPeriod.sampleStreams[i], internalPositionUs, joining,

--- a/library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
@@ -250,9 +250,9 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
    SampleStream[] newStreams = new SampleStream[newSelections.size()];
    for (int i = 0; i < newStreams.length; i++) {
      TrackSelection selection = newSelections.get(i);
-      Assertions.checkState(selection.length == 1);
+      Assertions.checkState(selection.length() == 1);
-      Assertions.checkState(selection.getTrack(0) == 0);
+      Assertions.checkState(selection.getIndexInTrackGroup(0) == 0);
-      int track = tracks.indexOf(selection.group);
+      int track = tracks.indexOf(selection.getTrackGroup());
      Assertions.checkState(!trackEnabledStates[track]);
      enabledTrackCount++;
      trackEnabledStates[track] = true;

--- a/library/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java
@@ -220,7 +220,7 @@ public final class MergingMediaPeriod implements MediaPeriod, MediaPeriod.Callba
    TrackGroupArray periodTrackGroups = period.getTrackGroups();
    for (int i = 0; i < allNewSelections.size(); i++) {
      TrackSelection selection = allNewSelections.get(i);
-      if (periodTrackGroups.indexOf(selection.group) != -1) {
+      if (periodTrackGroups.indexOf(selection.getTrackGroup()) != -1) {
        newSelectionOriginalIndices[newSelections.size()] = i;
        newSelections.add(selection);
      }

--- a/library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java
@@ -150,7 +150,6 @@ public class ChunkSampleStream<T extends ChunkSource> implements SampleStream, S
   * This method should be called when the stream is no longer required.
   */
  public void release() {
-    chunkSource.release();
    sampleQueue.disable();
    loader.release();
  }

--- a/library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkSource.java
@@ -84,11 +84,4 @@ public interface ChunkSource {
   */
  boolean onChunkLoadError(Chunk chunk, boolean cancelable, Exception e);
-  /**
-   * Releases the source.
-   * <p>
-   * This method should be called when the source is no longer required.
-   */
-  void release();
 }
--- a/library/src/main/java/com/google/android/exoplayer2/source/chunk/FormatEvaluator.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/chunk/FormatEvaluator.java
--- a/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaPeriod.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaPeriod.java
@@ -222,7 +222,7 @@ import java.util.List;
  private ChunkSampleStream<DashChunkSource> buildSampleStream(TrackSelection selection,
      long positionUs) {
-    int adaptationSetIndex = trackGroups.indexOf(selection.group);
+    int adaptationSetIndex = trackGroups.indexOf(selection.getTrackGroup());
    AdaptationSet adaptationSet = period.adaptationSets.get(adaptationSetIndex);
    DashChunkSource chunkSource = chunkSourceFactory.createDashChunkSource(
        manifestLoaderErrorThrower, manifest, index, adaptationSetIndex, selection,

--- a/library/src/main/java/com/google/android/exoplayer2/source/dash/DefaultDashChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/dash/DefaultDashChunkSource.java
@@ -28,8 +28,6 @@ import com.google.android.exoplayer2.source.chunk.Chunk;
 import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper;
 import com.google.android.exoplayer2.source.chunk.ChunkHolder;
 import com.google.android.exoplayer2.source.chunk.ContainerMediaChunk;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator.Evaluation;
 import com.google.android.exoplayer2.source.chunk.InitializationChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.SingleSampleMediaChunk;
@@ -56,25 +54,19 @@ public class DefaultDashChunkSource implements DashChunkSource {
  public static final class Factory implements DashChunkSource.Factory {
-    private final FormatEvaluator.Factory formatEvaluatorFactory;
    private final DataSource.Factory dataSourceFactory;
-    public Factory(DataSource.Factory dataSourceFactory,
+    public Factory(DataSource.Factory dataSourceFactory) {
-        FormatEvaluator.Factory formatEvaluatorFactory) {
      this.dataSourceFactory = dataSourceFactory;
-      this.formatEvaluatorFactory = formatEvaluatorFactory;
    }
    @Override
    public DashChunkSource createDashChunkSource(LoaderErrorThrower manifestLoaderErrorThrower,
        DashManifest manifest, int periodIndex, int adaptationSetIndex,
        TrackSelection trackSelection, long elapsedRealtimeOffsetMs) {
-      FormatEvaluator adaptiveEvaluator = trackSelection.length > 1
-          ? formatEvaluatorFactory.createFormatEvaluator() : null;
      DataSource dataSource = dataSourceFactory.createDataSource();
-     return new DefaultDashChunkSource(manifestLoaderErrorThrower, manifest, periodIndex,
+      return new DefaultDashChunkSource(manifestLoaderErrorThrower, manifest, periodIndex,
-         adaptationSetIndex, trackSelection, dataSource, adaptiveEvaluator,
+          adaptationSetIndex, trackSelection, dataSource, elapsedRealtimeOffsetMs);
-         elapsedRealtimeOffsetMs);
    }
  }
@@ -83,16 +75,12 @@ public class DefaultDashChunkSource implements DashChunkSource {
  private final int adaptationSetIndex;
  private final TrackSelection trackSelection;
  private final RepresentationHolder[] representationHolders;
-  private final boolean[] adaptiveFormatBlacklistFlags;
  private final DataSource dataSource;
-  private final FormatEvaluator adaptiveFormatEvaluator;
  private final long elapsedRealtimeOffsetUs;
-  private final Evaluation evaluation;
  private DashManifest manifest;
  private int periodIndex;
-  private boolean lastChunkWasInitialization;
  private IOException fatalError;
  private boolean missingLastSegment;
@@ -103,38 +91,28 @@ public class DefaultDashChunkSource implements DashChunkSource {
   * @param adaptationSetIndex The index of the adaptation set in the period.
   * @param trackSelection The track selection.
   * @param dataSource A {@link DataSource} suitable for loading the media data.
-   * @param adaptiveFormatEvaluator For adaptive tracks, selects from the available formats.
   * @param elapsedRealtimeOffsetMs If known, an estimate of the instantaneous difference between
   *     server-side unix time and {@link SystemClock#elapsedRealtime()} in milliseconds, specified
   *     as the server's unix time minus the local elapsed time. If unknown, set to 0.
   */
  public DefaultDashChunkSource(LoaderErrorThrower manifestLoaderErrorThrower,
      DashManifest manifest, int periodIndex, int adaptationSetIndex, TrackSelection trackSelection,
-      DataSource dataSource, FormatEvaluator adaptiveFormatEvaluator,
+      DataSource dataSource, long elapsedRealtimeOffsetMs) {
-      long elapsedRealtimeOffsetMs) {
    this.manifestLoaderErrorThrower = manifestLoaderErrorThrower;
    this.manifest = manifest;
    this.adaptationSetIndex = adaptationSetIndex;
    this.trackSelection = trackSelection;
    this.dataSource = dataSource;
-    this.adaptiveFormatEvaluator = adaptiveFormatEvaluator;
    this.periodIndex = periodIndex;
    this.elapsedRealtimeOffsetUs = elapsedRealtimeOffsetMs * 1000;
-    this.evaluation = new Evaluation();
    long periodDurationUs = getPeriodDurationUs();
    List<Representation> representations = getRepresentations();
-    representationHolders = new RepresentationHolder[trackSelection.length];
+    representationHolders = new RepresentationHolder[trackSelection.length()];
-    for (int i = 0; i < trackSelection.length; i++) {
+    for (int i = 0; i < representationHolders.length; i++) {
-      Representation representation = representations.get(trackSelection.getTrack(i));
+      Representation representation = representations.get(trackSelection.getIndexInTrackGroup(i));
      representationHolders[i] = new RepresentationHolder(periodDurationUs, representation);
    }
-    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.enable(trackSelection.getFormats());
-      adaptiveFormatBlacklistFlags = new boolean[trackSelection.length];
-    } else {
-      adaptiveFormatBlacklistFlags = null;
-    }
  }
  @Override
@@ -144,8 +122,8 @@ public class DefaultDashChunkSource implements DashChunkSource {
      periodIndex = newPeriodIndex;
      long periodDurationUs = getPeriodDurationUs();
      List<Representation> representations = getRepresentations();
-      for (int i = 0; i < trackSelection.length; i++) {
+      for (int i = 0; i < representationHolders.length; i++) {
-        Representation representation = representations.get(trackSelection.getTrack(i));
+        Representation representation = representations.get(trackSelection.getIndexInTrackGroup(i));
        representationHolders[i].updateRepresentation(periodDurationUs, representation);
      }
    } catch (BehindLiveWindowException e) {
@@ -164,11 +142,10 @@ public class DefaultDashChunkSource implements DashChunkSource {
  @Override
  public int getPreferredQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
-    if (fatalError != null || trackSelection.length < 2) {
+    if (fatalError != null || trackSelection.length() < 2) {
      return queue.size();
    }
-    return adaptiveFormatEvaluator.evaluateQueueSize(playbackPositionUs, queue,
+    return trackSelection.evaluateQueueSize(playbackPositionUs, queue);
-        adaptiveFormatBlacklistFlags);
  }
  @Override
@@ -177,25 +154,11 @@ public class DefaultDashChunkSource implements DashChunkSource {
      return;
    }
-    if (evaluation.format == null || !lastChunkWasInitialization) {
+    long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
-      if (trackSelection.length > 1) {
+    trackSelection.updateSelectedTrack(bufferedDurationUs);
-        long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
-        adaptiveFormatEvaluator.evaluateFormat(bufferedDurationUs, adaptiveFormatBlacklistFlags,
-            evaluation);
-      } else {
-        evaluation.format = trackSelection.getFormat(0);
-        evaluation.reason = C.SELECTION_REASON_UNKNOWN;
-        evaluation.data = null;
-      }
-    }
-    Format selectedFormat = evaluation.format;
-    if (selectedFormat == null) {
-      return;
-    }
    RepresentationHolder representationHolder =
-        representationHolders[trackSelection.indexOf(selectedFormat)];
+        representationHolders[trackSelection.getSelectedIndex()];
    Representation selectedRepresentation = representationHolder.representation;
    DashSegmentIndex segmentIndex = representationHolder.segmentIndex;
@@ -211,9 +174,8 @@ public class DefaultDashChunkSource implements DashChunkSource {
    if (pendingInitializationUri != null || pendingIndexUri != null) {
      // We have initialization and/or index requests to make.
      Chunk initializationChunk = newInitializationChunk(representationHolder, dataSource,
-          selectedFormat, evaluation.reason, evaluation.data, pendingInitializationUri,
+          trackSelection.getSelectedFormat(), trackSelection.getSelectionReason(),
-          pendingIndexUri);
+          trackSelection.getSelectionData(), pendingInitializationUri, pendingIndexUri);
-      lastChunkWasInitialization = true;
      out.chunk = initializationChunk;
      return;
    }
@@ -256,9 +218,9 @@ public class DefaultDashChunkSource implements DashChunkSource {
      return;
    }
-    Chunk nextMediaChunk = newMediaChunk(representationHolder, dataSource, selectedFormat,
+    Chunk nextMediaChunk = newMediaChunk(representationHolder, dataSource,
-        evaluation.reason, evaluation.data, sampleFormat, segmentNum);
+        trackSelection.getSelectedFormat(), trackSelection.getSelectionReason(),
-    lastChunkWasInitialization = false;
+        trackSelection.getSelectionData(), sampleFormat, segmentNum);
    out.chunk = nextMediaChunk;
  }
@@ -303,13 +265,6 @@ public class DefaultDashChunkSource implements DashChunkSource {
    return false;
  }
-  @Override
-  public void release() {
-    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.disable();
-    }
-  }
  // Private methods.
  private List<Representation> getRepresentations() {

--- a/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
--- a/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
@@ -28,7 +28,6 @@ import com.google.android.exoplayer2.source.SinglePeriodTimeline;
 import com.google.android.exoplayer2.source.Timeline;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMasterPlaylist;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist;
 import com.google.android.exoplayer2.source.hls.playlist.HlsPlaylist;
@@ -64,7 +63,6 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
  private final Uri manifestUri;
  private final DataSource.Factory dataSourceFactory;
-  private final FormatEvaluator.Factory formatEvaluatorFactory;
  private final int minLoadableRetryCount;
  private final EventDispatcher eventDispatcher;
  private final IdentityHashMap<SampleStream, HlsSampleStreamWrapper> sampleStreamSources;
@@ -89,19 +87,17 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
  private HlsSampleStreamWrapper[] enabledSampleStreamWrappers;
  private CompositeSequenceableLoader sequenceableLoader;
-  public HlsMediaSource(Uri manifestUri, DataSource.Factory dataSourceFactory,
+  public HlsMediaSource(Uri manifestUri, DataSource.Factory dataSourceFactory, Handler eventHandler,
-      FormatEvaluator.Factory formatEvaluatorFactory, Handler eventHandler,
      AdaptiveMediaSourceEventListener eventListener) {
-    this(manifestUri, dataSourceFactory, formatEvaluatorFactory, DEFAULT_MIN_LOADABLE_RETRY_COUNT,
+    this(manifestUri, dataSourceFactory, DEFAULT_MIN_LOADABLE_RETRY_COUNT, eventHandler,
-        eventHandler, eventListener);
+        eventListener);
  }
  public HlsMediaSource(Uri manifestUri, DataSource.Factory dataSourceFactory,
-      FormatEvaluator.Factory formatEvaluatorFactory, int minLoadableRetryCount,
+      int minLoadableRetryCount, Handler eventHandler,
-      Handler eventHandler, AdaptiveMediaSourceEventListener eventListener) {
+      AdaptiveMediaSourceEventListener eventListener) {
    this.manifestUri = manifestUri;
    this.dataSourceFactory = dataSourceFactory;
-    this.formatEvaluatorFactory = formatEvaluatorFactory;
    this.minLoadableRetryCount = minLoadableRetryCount;
    eventDispatcher = new EventDispatcher(eventHandler, eventListener);
@@ -352,7 +348,7 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
          Format.NO_VALUE);
      Variant[] variants = new Variant[] {new Variant(playlist.baseUri, format, null)};
      sampleStreamWrappers.add(buildSampleStreamWrapper(C.TRACK_TYPE_DEFAULT, baseUri, variants,
-          formatEvaluatorFactory.createFormatEvaluator(), null, null));
+          null, null));
      return sampleStreamWrappers;
    }
@@ -386,8 +382,7 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
      Variant[] variants = new Variant[selectedVariants.size()];
      selectedVariants.toArray(variants);
      sampleStreamWrappers.add(buildSampleStreamWrapper(C.TRACK_TYPE_DEFAULT, baseUri, variants,
-          formatEvaluatorFactory.createFormatEvaluator(), masterPlaylist.muxedAudioFormat,
+          masterPlaylist.muxedAudioFormat, masterPlaylist.muxedCaptionFormat));
-          masterPlaylist.muxedCaptionFormat));
    }
    // Build the audio stream wrapper if applicable.
@@ -396,7 +391,7 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
      Variant[] variants = new Variant[audioVariants.size()];
      audioVariants.toArray(variants);
      sampleStreamWrappers.add(buildSampleStreamWrapper(C.TRACK_TYPE_AUDIO, baseUri, variants, null,
-          null, null));
+          null));
    }
    // Build the text stream wrapper if applicable.
@@ -405,18 +400,17 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
      Variant[] variants = new Variant[subtitleVariants.size()];
      subtitleVariants.toArray(variants);
      sampleStreamWrappers.add(buildSampleStreamWrapper(C.TRACK_TYPE_TEXT, baseUri, variants, null,
-          null, null));
+          null));
    }
    return sampleStreamWrappers;
  }
  private HlsSampleStreamWrapper buildSampleStreamWrapper(int trackType, String baseUri,
-      Variant[] variants, FormatEvaluator formatEvaluator, Format muxedAudioFormat,
+      Variant[] variants, Format muxedAudioFormat, Format muxedCaptionFormat) {
-      Format muxedCaptionFormat) {
    DataSource dataSource = dataSourceFactory.createDataSource();
    HlsChunkSource defaultChunkSource = new HlsChunkSource(baseUri, variants, dataSource,
-        timestampAdjusterProvider, formatEvaluator);
+        timestampAdjusterProvider);
    return new HlsSampleStreamWrapper(trackType, this, defaultChunkSource, allocator,
        preparePositionUs, muxedAudioFormat, muxedCaptionFormat, minLoadableRetryCount,
        eventDispatcher);
@@ -440,7 +434,7 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
    int[] newSelectionOriginalIndices = new int[allNewSelections.size()];
    for (int i = 0; i < allNewSelections.size(); i++) {
      TrackSelection selection = allNewSelections.get(i);
-      if (sampleStreamWrapperTrackGroups.indexOf(selection.group) != -1) {
+      if (sampleStreamWrapperTrackGroups.indexOf(selection.getTrackGroup()) != -1) {
        newSelectionOriginalIndices[newSelections.size()] = i;
        newSelections.add(selection);
      }

--- a/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java
@@ -168,11 +168,10 @@ import java.util.List;
    SampleStream[] newStreams = new SampleStream[newSelections.size()];
    for (int i = 0; i < newStreams.length; i++) {
      TrackSelection selection = newSelections.get(i);
-      int group = trackGroups.indexOf(selection.group);
+      int group = trackGroups.indexOf(selection.getTrackGroup());
-      int[] tracks = selection.getTracks();
      setTrackGroupEnabledState(group, true);
      if (group == primaryTrackGroupIndex) {
-        chunkSource.selectTracks(new TrackSelection(chunkSource.getTrackGroup(), tracks));
+        chunkSource.selectTracks(selection);
      }
      newStreams[i] = new SampleStreamImpl(group);
    }
@@ -236,7 +235,6 @@ import java.util.List;
  }
  public void release() {
-    chunkSource.release();
    int sampleQueueCount = sampleQueues.size();
    for (int i = 0; i < sampleQueueCount; i++) {
      sampleQueues.valueAt(i).disable();

--- a/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/DefaultSsChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/DefaultSsChunkSource.java
@@ -25,8 +25,6 @@ import com.google.android.exoplayer2.source.chunk.Chunk;
 import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper;
 import com.google.android.exoplayer2.source.chunk.ChunkHolder;
 import com.google.android.exoplayer2.source.chunk.ContainerMediaChunk;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator.Evaluation;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.smoothstreaming.manifest.SsManifest;
 import com.google.android.exoplayer2.source.smoothstreaming.manifest.SsManifest.StreamElement;
@@ -47,24 +45,19 @@ public class DefaultSsChunkSource implements SsChunkSource {
  public static final class Factory implements SsChunkSource.Factory {
-    private final FormatEvaluator.Factory formatEvaluatorFactory;
    private final DataSource.Factory dataSourceFactory;
-    public Factory(DataSource.Factory dataSourceFactory,
+    public Factory(DataSource.Factory dataSourceFactory) {
-        FormatEvaluator.Factory formatEvaluatorFactory) {
      this.dataSourceFactory = dataSourceFactory;
-      this.formatEvaluatorFactory = formatEvaluatorFactory;
    }
    @Override
    public SsChunkSource createChunkSource(LoaderErrorThrower manifestLoaderErrorThrower,
        SsManifest manifest, int elementIndex, TrackSelection trackSelection,
        TrackEncryptionBox[] trackEncryptionBoxes) {
-      FormatEvaluator adaptiveEvaluator = trackSelection.length > 1
-          ? formatEvaluatorFactory.createFormatEvaluator() : null;
      DataSource dataSource = dataSourceFactory.createDataSource();
      return new DefaultSsChunkSource(manifestLoaderErrorThrower, manifest, elementIndex,
-          trackSelection, dataSource, adaptiveEvaluator, trackEncryptionBoxes);
+          trackSelection, dataSource, trackEncryptionBoxes);
    }
  }
@@ -73,10 +66,7 @@ public class DefaultSsChunkSource implements SsChunkSource {
  private final int elementIndex;
  private final TrackSelection trackSelection;
  private final ChunkExtractorWrapper[] extractorWrappers;
-  private final boolean[] adaptiveFormatBlacklistFlags;
  private final DataSource dataSource;
-  private final Evaluation evaluation;
-  private final FormatEvaluator adaptiveFormatEvaluator;
  private SsManifest manifest;
  private int currentManifestChunkOffset;
@@ -89,26 +79,23 @@ public class DefaultSsChunkSource implements SsChunkSource {
   * @param elementIndex The index of the stream element in the manifest.
   * @param trackSelection The track selection.
   * @param dataSource A {@link DataSource} suitable for loading the media data.
-   * @param adaptiveFormatEvaluator For adaptive tracks, selects from the available formats.
   * @param trackEncryptionBoxes Track encryption boxes for the stream.
   */
  public DefaultSsChunkSource(LoaderErrorThrower manifestLoaderErrorThrower, SsManifest manifest,
      int elementIndex, TrackSelection trackSelection, DataSource dataSource,
-      FormatEvaluator adaptiveFormatEvaluator, TrackEncryptionBox[] trackEncryptionBoxes) {
+      TrackEncryptionBox[] trackEncryptionBoxes) {
    this.manifestLoaderErrorThrower = manifestLoaderErrorThrower;
    this.manifest = manifest;
    this.elementIndex = elementIndex;
    this.trackSelection = trackSelection;
    this.dataSource = dataSource;
-    this.adaptiveFormatEvaluator = adaptiveFormatEvaluator;
-    this.evaluation = new Evaluation();
    StreamElement streamElement = manifest.streamElements[elementIndex];
-    extractorWrappers = new ChunkExtractorWrapper[trackSelection.length];
+    extractorWrappers = new ChunkExtractorWrapper[trackSelection.length()];
-    for (int i = 0; i < trackSelection.length; i++) {
+    for (int i = 0; i < extractorWrappers.length; i++) {
-      int manifestTrackIndex = trackSelection.getTrack(i);
+      int manifestTrackIndex = trackSelection.getIndexInTrackGroup(i);
-      Format format = trackSelection.getFormat(i);
+      Format format = streamElement.formats[i];
      int nalUnitLengthFieldLength = streamElement.type == C.TRACK_TYPE_VIDEO ? 4 : -1;
      Track track = new Track(manifestTrackIndex, streamElement.type, streamElement.timescale,
          C.UNSET_TIME_US, manifest.durationUs, format, Track.TRANSFORMATION_NONE,
@@ -118,12 +105,6 @@ public class DefaultSsChunkSource implements SsChunkSource {
          | FragmentedMp4Extractor.FLAG_WORKAROUND_IGNORE_TFDT_BOX, track);
      extractorWrappers[i] = new ChunkExtractorWrapper(extractor, format, false);
    }
-    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.enable(trackSelection.getFormats());
-      adaptiveFormatBlacklistFlags = new boolean[trackSelection.length];
-    } else {
-      adaptiveFormatBlacklistFlags = null;
-    }
  }
  @Override
@@ -162,11 +143,10 @@ public class DefaultSsChunkSource implements SsChunkSource {
  @Override
  public int getPreferredQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
-    if (fatalError != null || trackSelection.length < 2) {
+    if (fatalError != null || trackSelection.length() < 2) {
      return queue.size();
    }
-    return adaptiveFormatEvaluator.evaluateQueueSize(playbackPositionUs, queue,
+    return trackSelection.evaluateQueueSize(playbackPositionUs, queue);
-        adaptiveFormatBlacklistFlags);
  }
  @Override
@@ -175,20 +155,8 @@ public class DefaultSsChunkSource implements SsChunkSource {
      return;
    }
-    if (trackSelection.length > 1) {
+    long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
-      long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
+    trackSelection.updateSelectedTrack(bufferedDurationUs);
-      adaptiveFormatEvaluator.evaluateFormat(bufferedDurationUs, adaptiveFormatBlacklistFlags,
-          evaluation);
-    } else {
-      evaluation.format = trackSelection.getFormat(0);
-      evaluation.reason = C.SELECTION_REASON_UNKNOWN;
-      evaluation.data = null;
-    }
-    Format selectedFormat = evaluation.format;
-    if (selectedFormat == null) {
-      return;
-    }
    StreamElement streamElement = manifest.streamElements[elementIndex];
    if (streamElement.chunkCount == 0) {
@@ -219,14 +187,15 @@ public class DefaultSsChunkSource implements SsChunkSource {
    long chunkEndTimeUs = chunkStartTimeUs + streamElement.getChunkDurationUs(chunkIndex);
    int currentAbsoluteChunkIndex = chunkIndex + currentManifestChunkOffset;
-    int trackSelectionIndex = trackSelection.indexOf(selectedFormat);
+    int trackSelectionIndex = trackSelection.getSelectedIndex();
    ChunkExtractorWrapper extractorWrapper = extractorWrappers[trackSelectionIndex];
-    int manifestTrackIndex = trackSelection.getTrack(trackSelectionIndex);
+    int manifestTrackIndex = trackSelection.getIndexInTrackGroup(trackSelectionIndex);
    Uri uri = streamElement.buildRequestUri(manifestTrackIndex, chunkIndex);
-    out.chunk = newMediaChunk(selectedFormat, dataSource, uri, null, currentAbsoluteChunkIndex,
+    out.chunk = newMediaChunk(trackSelection.getSelectedFormat(), dataSource, uri, null,
-        chunkStartTimeUs, chunkEndTimeUs, evaluation.reason, evaluation.data, extractorWrapper);
+        currentAbsoluteChunkIndex, chunkStartTimeUs, chunkEndTimeUs,
+        trackSelection.getSelectionReason(), trackSelection.getSelectionData(), extractorWrapper);
  }
  @Override
@@ -240,13 +209,6 @@ public class DefaultSsChunkSource implements SsChunkSource {
    return false;
  }
-  @Override
-  public void release() {
-    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.disable();
-    }
-  }
  // Private methods.
  private static MediaChunk newMediaChunk(Format format, DataSource dataSource, Uri uri,

--- a/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaPeriod.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaPeriod.java
@@ -199,7 +199,7 @@ import java.util.List;
  private ChunkSampleStream<SsChunkSource> buildSampleStream(TrackSelection selection,
      long positionUs) {
-    int streamElementIndex = trackGroups.indexOf(selection.group);
+    int streamElementIndex = trackGroups.indexOf(selection.getTrackGroup());
    SsChunkSource chunkSource = chunkSourceFactory.createChunkSource(manifestLoaderErrorThrower,
        manifest, streamElementIndex, selection, trackEncryptionBoxes);
    return new ChunkSampleStream<>(manifest.streamElements[streamElementIndex].type, chunkSource,

--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/AdaptiveVideoTrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/AdaptiveVideoTrackSelection.java
--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/BaseTrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/BaseTrackSelection.java
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.trackselection;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.Format.DecreasingBandwidthComparator;
+import com.google.android.exoplayer2.source.TrackGroup;
+import com.google.android.exoplayer2.source.chunk.MediaChunk;
+import com.google.android.exoplayer2.util.Assertions;
+import android.os.SystemClock;
+import java.util.Arrays;
+import java.util.List;
+/**
+ * An abstract base class suitable for most {@link TrackSelection} implementations.
+ */
+public abstract class BaseTrackSelection implements TrackSelection {
+  /**
+   * The selected {@link TrackGroup}.
+   */
+  protected final TrackGroup group;
+  /**
+   * The number of selected tracks within the {@link TrackGroup}. Always greater than zero.
+   */
+  protected final int length;
+  /**
+   * The indices of the selected tracks in {@link #group}, in order of decreasing bandwidth.
+   */
+  private final int[] tracks;
+  /**
+   * The {@link Format}s of the selected tracks, in order of decreasing bandwidth.
+   */
+  private final Format[] formats;
+  /**
+   * Selected track blacklist timestamps, in order of decreasing bandwidth.
+   */
+  private final long[] blacklistUntilTimes;
+  // Lazily initialized hashcode.
+  private int hashCode;
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   */
+  public BaseTrackSelection(TrackGroup group, int... tracks) {
+    Assertions.checkState(tracks.length > 0);
+    this.group = Assertions.checkNotNull(group);
+    this.length = tracks.length;
+    // Set the formats, sorted in order of decreasing bandwidth.
+    formats = new Format[length];
+    for (int i = 0; i < tracks.length; i++) {
+      formats[i] = group.getFormat(tracks[i]);
+    }
+    Arrays.sort(formats, new DecreasingBandwidthComparator());
+    // Set the format indices in the same order.
+    this.tracks = new int[length];
+    for (int i = 0; i < length; i++) {
+      this.tracks[i] = group.indexOf(formats[i]);
+    }
+    blacklistUntilTimes = new long[length];
+  }
+  @Override
+  public final TrackGroup getTrackGroup() {
+    return group;
+  }
+  @Override
+  public final int length() {
+    return tracks.length;
+  }
+  @Override
+  public final Format getFormat(int index) {
+    return formats[index];
+  }
+  @Override
+  public final int getIndexInTrackGroup(int index) {
+    return tracks[index];
+  }
+  @Override
+  public final int indexOf(Format format) {
+    for (int i = 0; i < length; i++) {
+      if (formats[i] == format) {
+        return i;
+      }
+    }
+    return -1;
+  }
+  @Override
+  public final int indexOf(int indexInTrackGroup) {
+    for (int i = 0; i < length; i++) {
+      if (tracks[i] == indexInTrackGroup) {
+        return i;
+      }
+    }
+    return -1;
+  }
+  @Override
+  public final Format getSelectedFormat() {
+    return formats[getSelectedIndex()];
+  }
+  @Override
+  public final int getSelectedIndexInTrackGroup() {
+    return tracks[getSelectedIndex()];
+  }
+  @Override
+  public int evaluateQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
+    return queue.size();
+  }
+  @Override
+  public final boolean blacklist(int index, long blacklistDurationMs) {
+    long nowMs = SystemClock.elapsedRealtime();
+    boolean canBlacklist = isBlacklisted(index, nowMs);
+    for (int i = 0; i < length && !canBlacklist; i++) {
+      canBlacklist = i != index && !isBlacklisted(index, nowMs);
+    }
+    if (!canBlacklist) {
+      return false;
+    }
+    blacklistUntilTimes[index] = Math.max(blacklistUntilTimes[index], nowMs + blacklistDurationMs);
+    return true;
+  }
+  /**
+   * Returns whether the track at the specified index in the selection is blaclisted.
+   *
+   * @param index The index of the track in the selection.
+   * @param nowMs The current time in the timebase of {@link SystemClock#elapsedRealtime()}.
+   */
+  protected final boolean isBlacklisted(int index, long nowMs) {
+    return blacklistUntilTimes[index] > nowMs;
+  }
+  // Object overrides.
+  @Override
+  public int hashCode() {
+    if (hashCode == 0) {
+      hashCode = 31 * System.identityHashCode(group) + Arrays.hashCode(tracks);
+    }
+    return hashCode;
+  }
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    BaseTrackSelection other = (BaseTrackSelection) obj;
+    return group == other.group && Arrays.equals(tracks, other.tracks);
+  }
+}
--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
@@ -51,6 +51,8 @@ public class DefaultTrackSelector extends MappingTrackSelector {
  private static final int[] NO_TRACKS = new int[0];
  private static final String TAG = "DefaultTrackSelector";
+  private final TrackSelection.Factory adaptiveVideoTrackSelectionFactory;
  // Audio and text.
  private String preferredLanguage;
@@ -64,8 +66,28 @@ public class DefaultTrackSelector extends MappingTrackSelector {
  private int viewportWidth;
  private int viewportHeight;
+  /**
+   * Constructs an instance that does not support adaptive video.
+   *
+   * @param eventHandler A handler to use when delivering events to listeners. May be null if
+   *     listeners will not be added.
+   */
  public DefaultTrackSelector(Handler eventHandler) {
+    this(eventHandler, null);
+  }
+  /**
+   * Constructs an instance that uses a factory to create adaptive video track selections.
+   *
+   * @param eventHandler A handler to use when delivering events to listeners. May be null if
+   *     listeners will not be added.
+   * @param adaptiveVideoTrackSelectionFactory A factory for adaptive video {@link TrackSelection}s,
+   *     or null if the selector should not support adaptive video.
+   */
+  public DefaultTrackSelector(Handler eventHandler,
+      TrackSelection.Factory adaptiveVideoTrackSelectionFactory) {
    super(eventHandler);
+    this.adaptiveVideoTrackSelectionFactory = adaptiveVideoTrackSelectionFactory;
    allowNonSeamlessAdaptiveness = true;
    exceedVideoConstraintsIfNecessary = true;
    maxVideoWidth = Integer.MAX_VALUE;
@@ -203,11 +225,8 @@ public class DefaultTrackSelector extends MappingTrackSelector {
          rendererTrackSelections[i] = selectTrackForVideoRenderer(rendererCapabilities[i],
              rendererTrackGroupArrays[i], rendererFormatSupports[i], maxVideoWidth, maxVideoHeight,
              allowNonSeamlessAdaptiveness, allowMixedMimeAdaptiveness, viewportWidth,
-              viewportHeight, orientationMayChange);
+              viewportHeight, orientationMayChange, adaptiveVideoTrackSelectionFactory,
-          if (rendererTrackSelections[i] == null && exceedVideoConstraintsIfNecessary) {
+              exceedVideoConstraintsIfNecessary);
-            rendererTrackSelections[i] = selectSmallestSupportedVideoTrack(
-                rendererTrackGroupArrays[i], rendererFormatSupports[i]);
-          }
          break;
        case C.TRACK_TYPE_AUDIO:
          rendererTrackSelections[i] = selectTrackForAudioRenderer(rendererTrackGroupArrays[i],
@@ -232,28 +251,35 @@ public class DefaultTrackSelector extends MappingTrackSelector {
      RendererCapabilities rendererCapabilities, TrackGroupArray trackGroups,
      int[][] formatSupport, int maxVideoWidth, int maxVideoHeight,
      boolean allowNonSeamlessAdaptiveness, boolean allowMixedMimeAdaptiveness, int viewportWidth,
-      int viewportHeight, boolean orientationMayChange) throws ExoPlaybackException {
+      int viewportHeight, boolean orientationMayChange,
-    int requiredAdaptiveSupport = allowNonSeamlessAdaptiveness
+      TrackSelection.Factory adaptiveVideoTrackSelectionFactory,
-        ? (RendererCapabilities.ADAPTIVE_NOT_SEAMLESS | RendererCapabilities.ADAPTIVE_SEAMLESS)
+      boolean exceedVideoConstraintsIfNecessary) throws ExoPlaybackException {
-        : RendererCapabilities.ADAPTIVE_SEAMLESS;
+    if (adaptiveVideoTrackSelectionFactory != null) {
-    boolean allowMixedMimeTypes = allowMixedMimeAdaptiveness
+      int requiredAdaptiveSupport = allowNonSeamlessAdaptiveness
-        && (rendererCapabilities.supportsMixedMimeTypeAdaptation() & requiredAdaptiveSupport) != 0;
+          ? (RendererCapabilities.ADAPTIVE_NOT_SEAMLESS | RendererCapabilities.ADAPTIVE_SEAMLESS)
-    TrackGroup largestAdaptiveGroup = null;
+          : RendererCapabilities.ADAPTIVE_SEAMLESS;
-    int[] largestAdaptiveGroupTracks = NO_TRACKS;
+      boolean allowMixedMimeTypes = allowMixedMimeAdaptiveness
-    for (int i = 0; i < trackGroups.length; i++) {
+          && (rendererCapabilities.supportsMixedMimeTypeAdaptation() & requiredAdaptiveSupport)
-      TrackGroup trackGroup = trackGroups.get(i);
+          != 0;
-      int[] adaptiveTracks = getAdaptiveTracksOfGroup(trackGroup, formatSupport[i],
+      TrackGroup largestAdaptiveGroup = null;
-          allowMixedMimeTypes, requiredAdaptiveSupport, maxVideoWidth, maxVideoHeight,
+      int[] largestAdaptiveGroupTracks = NO_TRACKS;
-          viewportWidth, viewportHeight, orientationMayChange);
+      for (int i = 0; i < trackGroups.length; i++) {
-      if (adaptiveTracks.length > largestAdaptiveGroupTracks.length) {
+        TrackGroup trackGroup = trackGroups.get(i);
-        largestAdaptiveGroup = trackGroup;
+        int[] adaptiveTracks = getAdaptiveTracksOfGroup(trackGroup, formatSupport[i],
-        largestAdaptiveGroupTracks = adaptiveTracks;
+            allowMixedMimeTypes, requiredAdaptiveSupport, maxVideoWidth, maxVideoHeight,
+            viewportWidth, viewportHeight, orientationMayChange);
+        if (adaptiveTracks.length > largestAdaptiveGroupTracks.length) {
+          largestAdaptiveGroup = trackGroup;
+          largestAdaptiveGroupTracks = adaptiveTracks;
+        }
+      }
+      if (largestAdaptiveGroup != null) {
+        return adaptiveVideoTrackSelectionFactory.createTrackSelection(largestAdaptiveGroup,
+            largestAdaptiveGroupTracks);
      }
-    }
-    if (largestAdaptiveGroup != null) {
-      return new TrackSelection(largestAdaptiveGroup, largestAdaptiveGroupTracks);
    }
+    // TODO: Should select the best supported video track, not the first one.
    // No adaptive tracks selection could be made, so we select the first supported video track.
    for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
      TrackGroup trackGroup = trackGroups.get(groupIndex);
@@ -261,10 +287,15 @@ public class DefaultTrackSelector extends MappingTrackSelector {
      for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
        if (isSupportedVideoTrack(trackFormatSupport[trackIndex], trackGroup.getFormat(trackIndex),
            maxVideoWidth, maxVideoHeight)) {
-          return new TrackSelection(trackGroup, trackIndex);
+          return new FixedTrackSelection(trackGroup, trackIndex);
        }
      }
    }
+    if (exceedVideoConstraintsIfNecessary) {
+      return selectSmallestSupportedVideoTrack(trackGroups, formatSupport);
+    }
    return null;
  }
@@ -350,8 +381,8 @@ public class DefaultTrackSelector extends MappingTrackSelector {
        }
      }
    }
-    return trackGroupSelection != null
+    return trackGroupSelection == null ? null
-        ? new TrackSelection(trackGroupSelection, trackIndexSelection) : null;
+        : new FixedTrackSelection(trackGroupSelection, trackIndexSelection);
  }
  private static boolean isSupportedVideoTrack(int formatSupport, Format format, int maxVideoWidth,
@@ -371,7 +402,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
        for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
          if (isSupported(trackFormatSupport[trackIndex])
              && formatHasLanguage(trackGroup.getFormat(trackIndex), preferredLanguage)) {
-            return new TrackSelection(trackGroup, trackIndex);
+            return new FixedTrackSelection(trackGroup, trackIndex);
          }
        }
      }
@@ -398,12 +429,13 @@ public class DefaultTrackSelector extends MappingTrackSelector {
            firstForcedTrack = trackIndex;
          }
          if (formatHasLanguage(trackGroup.getFormat(trackIndex), preferredLanguage)) {
-            return new TrackSelection(trackGroup, trackIndex);
+            return new FixedTrackSelection(trackGroup, trackIndex);
          }
        }
      }
    }
-    return firstForcedGroup != null ? new TrackSelection(firstForcedGroup, firstForcedTrack) : null;
+    return firstForcedGroup == null ? null
+        : new FixedTrackSelection(firstForcedGroup, firstForcedTrack);
  }
  // General track selection methods.
@@ -415,7 +447,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
      int[] trackFormatSupport = formatSupport[groupIndex];
      for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
        if (isSupported(trackFormatSupport[trackIndex])) {
-          return new TrackSelection(trackGroup, trackIndex);
+          return new FixedTrackSelection(trackGroup, trackIndex);
        }
      }
    }
@@ -492,7 +524,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
    // Before API 25 the platform Display object does not provide a working way to identify Android
    // TVs that can show 4k resolution in a SurfaceView, so check for supported devices here.
    if (Util.SDK_INT < 25) {
-      if ("Sony".equals(Util.MANUFACTURER) && Util.MODEL != null && Util.MODEL.startsWith("BRAVIA")
+      if ("Sony".equals(Util.MANUFACTURER) && Util.MODEL.startsWith("BRAVIA")
          && context.getPackageManager().hasSystemFeature("com.sony.dtv.hardware.panel.qfhd")) {
        return new Point(3840, 2160);
      } else if ("NVIDIA".equals(Util.MANUFACTURER) && Util.MODEL != null

--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/FixedTrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/FixedTrackSelection.java
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.trackselection;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.source.TrackGroup;
+/**
+ * A {@link TrackSelection} consisting of a single track.
+ */
+public final class FixedTrackSelection extends BaseTrackSelection {
+  private final int reason;
+  private final Object data;
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param track The index of the selected track within the {@link TrackGroup}.
+   */
+  public FixedTrackSelection(TrackGroup group, int track) {
+    this(group, track, C.SELECTION_REASON_UNKNOWN, null);
+  }
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param track The index of the selected track within the {@link TrackGroup}.
+   * @param reason A reason for the track selection.
+   * @param data Optional data associated with the track selection.
+   */
+  public FixedTrackSelection(TrackGroup group, int track, int reason, Object data) {
+    super(group, track);
+    this.reason = reason;
+    this.data = data;
+  }
+  @Override
+  public void updateSelectedTrack(long bufferedDurationUs) {
+    // Do nothing.
+  }
+  @Override
+  public int getSelectedIndex() {
+    return 0;
+  }
+  @Override
+  public int getSelectionReason() {
+    return reason;
+  }
+  @Override
+  public Object getSelectionData() {
+    return data;
+  }
+}
--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/RandomTrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/RandomTrackSelection.java
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.trackselection;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.source.TrackGroup;
+import android.os.SystemClock;
+import java.util.Random;
+/**
+ * A {@link TrackSelection} whose selected track is updated randomly.
+ */
+public final class RandomTrackSelection extends BaseTrackSelection {
+  private final Random random;
+  private int selectedIndex;
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   */
+  public RandomTrackSelection(TrackGroup group, int... tracks) {
+    super(group, tracks);
+    random = new Random();
+    selectedIndex = random.nextInt(length);
+  }
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   * @param seed A seed for the {@link Random} instance used to update the selected track.
+   */
+  public RandomTrackSelection(TrackGroup group, int[] tracks, long seed) {
+    super(group, tracks);
+    random = new Random(seed);
+    selectedIndex = random.nextInt(length);
+  }
+  @Override
+  public void updateSelectedTrack(long bufferedDurationUs) {
+    // Count the number of non-blacklisted formats.
+    long nowMs = SystemClock.elapsedRealtime();
+    int nonBlacklistedFormatCount = 0;
+    for (int i = 0; i < length; i++) {
+      if (!isBlacklisted(i, nowMs)) {
+        nonBlacklistedFormatCount++;
+      }
+    }
+    selectedIndex = random.nextInt(nonBlacklistedFormatCount);
+    if (nonBlacklistedFormatCount != length) {
+      // Adjust the format index to account for blacklisted formats.
+      nonBlacklistedFormatCount = 0;
+      for (int i = 0; i < length; i++) {
+        if (!isBlacklisted(i, nowMs) && selectedIndex == nonBlacklistedFormatCount++) {
+          selectedIndex = i;
+          return;
+        }
+      }
+    }
+  }
+  @Override
+  public int getSelectedIndex() {
+    return selectedIndex;
+  }
+  @Override
+  public int getSelectionReason() {
+    return C.SELECTION_REASON_ADAPTIVE;
+  }
+  @Override
+  public Object getSelectionData() {
+    return null;
+  }
+}
--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java
@@ -16,54 +16,48 @@
 package com.google.android.exoplayer2.trackselection;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.Format.DecreasingBandwidthComparator;
 import com.google.android.exoplayer2.source.TrackGroup;
-import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.source.chunk.MediaChunk;
-import java.util.Arrays;
+import java.util.List;
 /**
- * A track selection, consisting of a {@link TrackGroup} and a selected subset of the tracks within
+ * A track selection consisting of a static subset of selected tracks belonging to a
- * it. The selected tracks are exposed in order of decreasing bandwidth.
+ * {@link TrackGroup}, and a possibly varying individual selected track from the subset.
+ * <p>
+ * Tracks belonging to the subset are exposed in decreasing bandwidth order. The individual selected
+ * track may change as a result of calling {@link #updateSelectedTrack(long)}.
 */
-public final class TrackSelection {
+public interface TrackSelection {
  /**
-   * The selected {@link TrackGroup}.
+   * Factory for {@link TrackSelection} instances.
   */
-  public final TrackGroup group;
+  interface Factory {
-  /**
-   * The number of selected tracks within the {@link TrackGroup}. Always greater than zero.
+    /**
-   */
+     * Creates a new selection.
-  public final int length;
+     *
+     * @param group The {@link TrackGroup}. Must not be null.
+     * @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.
+     */
+    TrackSelection createTrackSelection(TrackGroup group, int... tracks);
-  private final int[] tracks;
+  }
-  private final Format[] formats;
-  // Lazily initialized hashcode.
+  /**
-  private int hashCode;
+   * Returns the {@link TrackGroup} to which the selected tracks belong.
+   */
+  TrackGroup getTrackGroup();
+  // Static subset of selected tracks.
  /**
-   * @param group The {@link TrackGroup}. Must not be null.
+   * Returns the number of tracks in the selection.
-   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
-   *     null or empty. May be in any order.
   */
-  public TrackSelection(TrackGroup group, int... tracks) {
+  int length();
-    Assertions.checkState(tracks.length > 0);
-    this.group = Assertions.checkNotNull(group);
-    this.length = tracks.length;
-    // Set the formats, sorted in order of decreasing bandwidth.
-    formats = new Format[length];
-    for (int i = 0; i < tracks.length; i++) {
-      formats[i] = group.getFormat(tracks[i]);
-    }
-    Arrays.sort(formats, new DecreasingBandwidthComparator());
-    // Set the format indices in the same order.
-    this.tracks = new int[length];
-    for (int i = 0; i < length; i++) {
-      this.tracks[i] = group.indexOf(formats[i]);
-    }
-  }
  /**
   * Returns the format of the track at a given index in the selection.
@@ -71,16 +65,15 @@ public final class TrackSelection {
   * @param index The index in the selection.
   * @return The format of the selected track.
   */
-  public Format getFormat(int index) {
+  Format getFormat(int index);
-    return formats[index];
-  }
  /**
-   * Returns a copy of the formats of the selected tracks.
+   * Returns the index in the track group of the track at a given index in the selection.
+   *
+   * @param index The index in the selection.
+   * @return The index of the selected track.
   */
-  public Format[] getFormats() {
+  int getIndexInTrackGroup(int index);
-    return formats.clone();
-  }
  /**
   * Returns the index in the selection of the track with the specified format.
@@ -89,66 +82,82 @@ public final class TrackSelection {
   * @return The index in the selection, or -1 if the track with the specified format is not part of
   *     the selection.
   */
-  public int indexOf(Format format) {
+  int indexOf(Format format);
-    for (int i = 0; i < length; i++) {
-      if (formats[i] == format) {
-        return i;
-      }
-    }
-    return -1;
-  }
  /**
-   * Returns the index in the track group of the track at a given index in the selection.
+   * Returns the index in the selection of the track with the specified index in the track group.
   *
-   * @param index The index in the selection.
+   * @param indexInTrackGroup The index in the track group.
-   * @return The index of the selected track.
+   * @return The index in the selection, or -1 if the track with the specified index is not part of
+   *     the selection.
   */
-  public int getTrack(int index) {
+  int indexOf(int indexInTrackGroup);
-    return tracks[index];
-  }
+  // Individual selected track.
  /**
-   * Returns a copy of the selected tracks in the track group.
+   * Returns the {@link Format} of the individual selected track.
   */
-  public int[] getTracks() {
+  Format getSelectedFormat();
-    return tracks.clone();
-  }
  /**
-   * Returns the index in the selection of the track with the specified index in the track group.
+   * Returns the index in the track group of the individual selected track.
+   */
+  int getSelectedIndexInTrackGroup();
+  /**
+   * Returns the index of the selected track.
+   */
+  int getSelectedIndex();
+  /**
+   * Returns the reason for the current track selection.
+   */
+  int getSelectionReason();
+  /**
+   * Returns optional data associated with the current track selection.
+   */
+  Object getSelectionData();
+  // Adaptation.
+  /**
+   * Updates the selected track.
   *
-   * @param trackIndex The index in the track group.
+   * @param bufferedDurationUs The duration of media currently buffered in microseconds.
-   * @return The index in the selection, or -1 if the track with the specified index is not part of
-   *     the selection.
   */
-  public int indexOf(int trackIndex) {
+  void updateSelectedTrack(long bufferedDurationUs);
-    for (int i = 0; i < length; i++) {
-      if (tracks[i] == trackIndex) {
-        return i;
-      }
-    }
-    return -1;
-  }
-  @Override
+  /**
-  public int hashCode() {
+   * May be called periodically by sources that load media in discrete {@link MediaChunk}s and
-    if (hashCode == 0) {
+   * support discarding of buffered chunks in order to re-buffer using a different selected track.
-      hashCode = 31 * System.identityHashCode(group) + Arrays.hashCode(tracks);
+   * Returns the number of chunks that should be retained in the queue.
-    }
+   * <p>
-    return hashCode;
+   * To avoid excessive re-buffering, implementations should normally return the size of the queue.
-  }
+   * An example of a case where a smaller value may be returned is if network conditions have
+   * improved dramatically, allowing chunks to be discarded and re-buffered in a track of
+   * significantly higher quality. Discarding chunks may allow faster switching to a higher quality
+   * track in this case.
+   *
+   * @param playbackPositionUs The current playback position in microseconds.
+   * @param queue The queue of buffered {@link MediaChunk}s. Must not be modified.
+   * @return The number of chunks to retain in the queue.
+   */
+  int evaluateQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue);
-  @Override
+  /**
-  public boolean equals(Object obj) {
+   * Attempts to blacklist the track at the specified index in the selection, making it ineligible
-    if (this == obj) {
+   * for selection by calls to {@link #updateSelectedTrack(long)} for the specified period of time.
-      return true;
+   * Blacklisting will fail if all other tracks are currently blacklisted. If blacklisting the
-    }
+   * currently selected track, note that it will remain selected until the next call to
-    if (obj == null || getClass() != obj.getClass()) {
+   * {@link #updateSelectedTrack(long)}.
-      return false;
+   *
-    }
+   * @param index The index of the track in the selection.
-    TrackSelection other = (TrackSelection) obj;
+   * @param blacklistDurationMs The duration of time for which the track should be blacklisted, in
-    return group == other.group && Arrays.equals(tracks, other.tracks);
+   *     milliseconds.
-  }
+   * @return Whether blacklisting was successful.
+   */
+  boolean blacklist(int index, long blacklistDurationMs);
 }
--- a/playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/gts/DashTest.java
+++ b/playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/gts/DashTest.java
@@ -34,17 +34,18 @@ import com.google.android.exoplayer2.playbacktests.util.MetricsLogger;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator.AdaptiveEvaluator;
 import com.google.android.exoplayer2.source.dash.DashMediaSource;
 import com.google.android.exoplayer2.source.dash.DefaultDashChunkSource;
+import com.google.android.exoplayer2.trackselection.FixedTrackSelection;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
+import com.google.android.exoplayer2.trackselection.RandomTrackSelection;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.upstream.DataSource;
-import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
 import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSource;
 import com.google.android.exoplayer2.upstream.HttpDataSource;
+import com.google.android.exoplayer2.upstream.TransferListener;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
@@ -680,15 +681,16 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
      this.isWidevineEncrypted = isWidevineEncrypted;
      this.videoMimeType = videoMimeType;
      this.isCddLimitedRetry = isCddLimitedRetry;
-      trackSelector = new DashTestTrackSelector(new String[] {audioFormat},
+      trackSelector = new DashTestTrackSelector(audioFormat, videoFormats,
-          videoFormats, canIncludeAdditionalVideoFormats);
+          canIncludeAdditionalVideoFormats);
      if (actionSchedule != null) {
        setSchedule(actionSchedule);
      }
    }
    @Override
-    protected MappingTrackSelector buildTrackSelector(HostActivity host) {
+    protected MappingTrackSelector buildTrackSelector(HostActivity host,
+        BandwidthMeter bandwidthMeter) {
      return trackSelector;
    }
@@ -731,19 +733,17 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
    }
    @Override
-    public MediaSource buildSource(HostActivity host, String userAgent) {
+    public MediaSource buildSource(HostActivity host, String userAgent,
+        TransferListener mediaTransferListener) {
      DataSource.Factory manifestDataSourceFactory = new DefaultDataSourceFactory(host, userAgent);
-      DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
      DataSource.Factory mediaDataSourceFactory = new DefaultDataSourceFactory(host, userAgent,
-          bandwidthMeter);
+          mediaTransferListener);
-      FormatEvaluator.Factory formatEvaluatorFactory = new AdaptiveEvaluator.Factory(
-          bandwidthMeter);
      String manifestUrl = manifestPath;
      manifestUrl += isWidevineEncrypted ? (needsSecureVideoDecoder ? WIDEVINE_L1_SUFFIX
          : WIDEVINE_L3_SUFFIX) : "";
      Uri manifestUri = Uri.parse(manifestUrl);
      DefaultDashChunkSource.Factory chunkSourceFactory = new DefaultDashChunkSource.Factory(
-          mediaDataSourceFactory, formatEvaluatorFactory);
+          mediaDataSourceFactory);
      return new DashMediaSource(manifestUri, manifestDataSourceFactory, chunkSourceFactory,
          MIN_LOADABLE_RETRY_COUNT, null, null);
    }
@@ -801,16 +801,16 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
  private static final class DashTestTrackSelector extends MappingTrackSelector {
-    private final String[] audioFormatIds;
+    private final String audioFormatId;
    private final String[] videoFormatIds;
    private final boolean canIncludeAdditionalVideoFormats;
    public boolean includedAdditionalVideoFormats;
-    private DashTestTrackSelector(String[] audioFormatIds, String[] videoFormatIds,
+    private DashTestTrackSelector(String audioFormatId, String[] videoFormatIds,
        boolean canIncludeAdditionalVideoFormats) {
      super(null);
-      this.audioFormatIds = audioFormatIds;
+      this.audioFormatId = audioFormatId;
      this.videoFormatIds = videoFormatIds;
      this.canIncludeAdditionalVideoFormats = canIncludeAdditionalVideoFormats;
    }
@@ -826,17 +826,17 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
      Assertions.checkState(rendererTrackGroupArrays[VIDEO_RENDERER_INDEX].length == 1);
      Assertions.checkState(rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].length == 1);
      TrackSelection[] selections = new TrackSelection[rendererCapabilities.length];
-      selections[VIDEO_RENDERER_INDEX] = new TrackSelection(
+      selections[VIDEO_RENDERER_INDEX] = new RandomTrackSelection(
          rendererTrackGroupArrays[VIDEO_RENDERER_INDEX].get(0),
          getTrackIndices(rendererTrackGroupArrays[VIDEO_RENDERER_INDEX].get(0),
              rendererFormatSupports[VIDEO_RENDERER_INDEX][0], videoFormatIds,
-              canIncludeAdditionalVideoFormats));
+              canIncludeAdditionalVideoFormats),
-      selections[AUDIO_RENDERER_INDEX] = new TrackSelection(
+          0 /* seed */);
+      selections[AUDIO_RENDERER_INDEX] = new FixedTrackSelection(
          rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].get(0),
-          getTrackIndices(rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].get(0),
+          getTrackIndex(rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].get(0), audioFormatId));
-              rendererFormatSupports[AUDIO_RENDERER_INDEX][0], audioFormatIds, false));
      includedAdditionalVideoFormats =
-          selections[VIDEO_RENDERER_INDEX].length > videoFormatIds.length;
+          selections[VIDEO_RENDERER_INDEX].length() > videoFormatIds.length;
      return selections;
    }
@@ -844,18 +844,9 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
        String[] formatIds, boolean canIncludeAdditionalFormats) {
      List<Integer> trackIndices = new ArrayList<>();
-      // Always select explicitly listed representations, failing if they're missing.
+      // Always select explicitly listed representations.
      for (String formatId : formatIds) {
-        boolean foundIndex = false;
+        trackIndices.add(getTrackIndex(trackGroup, formatId));
-        for (int j = 0; j < trackGroup.length && !foundIndex; j++) {
-          if (trackGroup.getFormat(j).id.equals(formatId)) {
-            trackIndices.add(j);
-            foundIndex = true;
-          }
-        }
-        if (!foundIndex) {
-          throw new IllegalStateException("Format " + formatId + " not found.");
-        }
      }
      // Select additional video representations, if supported by the device.
@@ -873,6 +864,15 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
      return trackIndicesArray;
    }
+    private static int getTrackIndex(TrackGroup trackGroup, String formatId) {
+      for (int i = 0; i < trackGroup.length; i++) {
+        if (trackGroup.getFormat(i).id.equals(formatId)) {
+          return i;
+        }
+      }
+      throw new IllegalStateException("Format " + formatId + " not found.");
+    }
    private static boolean isFormatHandled(int formatSupport) {
      return (formatSupport & RendererCapabilities.FORMAT_SUPPORT_MASK)
          == RendererCapabilities.FORMAT_HANDLED;

--- a/playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/util/ExoHostedTest.java
+++ b/playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/util/ExoHostedTest.java
@@ -27,15 +27,18 @@ import com.google.android.exoplayer2.drm.DrmSessionManager;
 import com.google.android.exoplayer2.playbacktests.util.HostActivity.HostedTest;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.Timeline;
+import com.google.android.exoplayer2.trackselection.AdaptiveVideoTrackSelection;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
+import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
+import com.google.android.exoplayer2.upstream.TransferListener;
 import com.google.android.exoplayer2.util.Util;
 import android.os.Handler;
 import android.os.SystemClock;
 import android.util.Log;
 import android.view.Surface;
 import junit.framework.Assert;
@@ -123,11 +126,12 @@ public abstract class ExoHostedTest implements HostedTest, ExoPlayer.EventListen
  @Override
  public final void onStart(HostActivity host, Surface surface) {
    // Build the player.
-    trackSelector = buildTrackSelector(host);
+    DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
+    trackSelector = buildTrackSelector(host, bandwidthMeter);
    String userAgent = "ExoPlayerPlaybackTests";
    DrmSessionManager drmSessionManager = buildDrmSessionManager(userAgent);
    player = buildExoPlayer(host, surface, trackSelector, drmSessionManager);
-    player.setMediaSource(buildSource(host, Util.getUserAgent(host, userAgent)));
+    player.setMediaSource(buildSource(host, Util.getUserAgent(host, userAgent), bandwidthMeter));
    player.addListener(this);
    player.setDebugListener(this);
    player.setPlayWhenReady(true);
@@ -288,8 +292,9 @@ public abstract class ExoHostedTest implements HostedTest, ExoPlayer.EventListen
  }
  @SuppressWarnings("unused")
-  protected MappingTrackSelector buildTrackSelector(HostActivity host) {
+  protected MappingTrackSelector buildTrackSelector(HostActivity host,
-    return new DefaultTrackSelector(null);
+      BandwidthMeter bandwidthMeter) {
+    return new DefaultTrackSelector(null, new AdaptiveVideoTrackSelection.Factory(bandwidthMeter));
  }
  @SuppressWarnings("unused")
@@ -302,7 +307,8 @@ public abstract class ExoHostedTest implements HostedTest, ExoPlayer.EventListen
  }
  @SuppressWarnings("unused")
-  protected abstract MediaSource buildSource(HostActivity host, String userAgent);
+  protected abstract MediaSource buildSource(HostActivity host, String userAgent,
+      TransferListener mediaTransferListener);
  @SuppressWarnings("unused")
  protected void onPlayerErrorInternal(ExoPlaybackException error) {