Simplification: Move common logic to TrackSelection

- TrackSelection now exposes the selected formats, ordered by decreasing bandwidth. This removes the need for DASH, SS and HLS to do the sorting individually. - The change also removes the need to reconstruct TrackSelection instances with a different group index in various places (e.g. MergingMediaPeriod). - This is also a step toward potentially packaging the FormatEvaluator inside of the TrackSelection (TBD). ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=128159064

Simplification: Move common logic to TrackSelection
- TrackSelection now exposes the selected formats, ordered by decreasing bandwidth. This removes the need for DASH, SS and HLS to do the sorting individually. - The change also removes the need to reconstruct TrackSelection instances with a different group index in various places (e.g. MergingMediaPeriod). - This is also a step toward potentially packaging the FormatEvaluator inside of the TrackSelection (TBD). ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=128159064
692d756e · olly · Oliver Woodman · 6f1b24f1 · 692d756e · 692d756e
Commit 692d756e authored Jul 22, 2016 by olly Committed by Oliver Woodman Jul 22, 2016
Showing with 239 additions and 342 deletions
demo/src/main/java/com/google/android/exoplayer2/demo/EventLogger.java
demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
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/TrackGroup.java
library/src/main/java/com/google/android/exoplayer2/source/TrackGroupArray.java
library/src/main/java/com/google/android/exoplayer2/source/dash/DashChunkSource.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/SsChunkSource.java
library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
library/src/main/java/com/google/android/exoplayer2/trackselection/MappingTrackSelector.java
library/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java
playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/gts/DashTest.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
@@ -109,7 +109,7 @@ public class EventLogger implements ExoPlayer.EventListener, SimpleExoPlayer.Deb
              trackGroup.length, trackInfo.getAdaptiveSupport(rendererIndex, groupIndex, false));
          Log.d(TAG, "    Group:" + groupIndex + ", adaptive_supported=" + adaptiveSupport + " [");
          for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
-            String status = getTrackStatusString(trackSelection, groupIndex, trackIndex);
+            String status = getTrackStatusString(trackSelection, trackGroup, trackIndex);
            String formatSupport = getFormatSupportString(
                trackInfo.getTrackFormatSupport(rendererIndex, groupIndex, trackIndex));
            Log.d(TAG, "      " + status + " Track:" + trackIndex + ", "
@@ -353,9 +353,9 @@ public class EventLogger implements ExoPlayer.EventListener, SimpleExoPlayer.Deb
    return builder.toString();
  }
-  private static String getTrackStatusString(TrackSelection selection, int groupIndex,
+  private static String getTrackStatusString(TrackSelection selection, TrackGroup group,
      int trackIndex) {
-    boolean groupEnabled = selection != null && selection.group == groupIndex;
+    boolean groupEnabled = selection != null && selection.group == group;
    if (groupEnabled) {
      for (int i = 0; i < selection.length; i++) {
        if (selection.getTrack(i) == trackIndex) {

--- a/demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
+++ b/demo/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionHelper.java
@@ -135,7 +135,7 @@ import java.util.Locale;
        if (trackInfo.getTrackFormatSupport(rendererIndex, groupIndex, trackIndex)
            == RendererCapabilities.FORMAT_HANDLED) {
          haveSupportedTracks = true;
-          trackView.setTag(Pair.create(groupIndex, trackIndex));
+          trackView.setTag(Pair.create(group, trackIndex));
          trackView.setOnClickListener(this);
        } else {
          trackView.setEnabled(false);
@@ -160,7 +160,7 @@ import java.util.Locale;
    for (int i = 0; i < trackViews.length; i++) {
      for (int j = 0; j < trackViews[i].length; j++) {
        trackViews[i][j].setChecked(
-            override != null && override.group == i && override.containsTrack(j));
+            override != null && override.group == trackGroups.get(i) && override.indexOf(j) != -1);
      }
    }
  }
@@ -194,11 +194,11 @@ import java.util.Locale;
    } else {
      isDisabled = false;
      @SuppressWarnings("unchecked")
-      Pair<Integer, Integer> tag = (Pair<Integer, Integer>) view.getTag();
+      Pair<TrackGroup, Integer> tag = (Pair<TrackGroup, Integer>) view.getTag();
-      int groupIndex = tag.first;
+      TrackGroup group = tag.first;
      int trackIndex = tag.second;
-      if (!trackGroupsAdaptive[groupIndex] || override == null) {
+      if (!trackGroupsAdaptive[trackGroups.indexOf(group)] || override == null) {
-        override = new TrackSelection(groupIndex, trackIndex);
+        override = new TrackSelection(group, trackIndex);
      } else {
        // The group being modified is adaptive and we already have a non-null override.
        boolean isEnabled = ((CheckedTextView) view).isChecked();
@@ -216,13 +216,13 @@ import java.util.Locale;
                tracks[trackCount++] = override.getTrack(i);
              }
            }
-            override = new TrackSelection(groupIndex, tracks);
+            override = new TrackSelection(group, tracks);
          }
        } else {
          // Add the track to the override.
          int[] tracks = Arrays.copyOf(override.getTracks(), override.length + 1);
          tracks[tracks.length - 1] = trackIndex;
-          override = new TrackSelection(groupIndex, tracks);
+          override = new TrackSelection(group, tracks);
        }
      }
    }

--- a/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
+++ b/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
@@ -19,7 +19,6 @@ import com.google.android.exoplayer2.ExoPlayer.ExoPlayerMessage;
 import com.google.android.exoplayer2.source.MediaPeriod;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.SampleStream;
-import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
 import com.google.android.exoplayer2.trackselection.TrackSelector;
@@ -705,7 +704,6 @@ import java.util.ArrayList;
        TrackSelectionArray oldTrackSelections = readingPeriod.trackSelections;
        readingPeriod = readingPeriod.nextPeriod;
        TrackSelectionArray newTrackSelections = readingPeriod.trackSelections;
-        TrackGroupArray groups = readingPeriod.mediaPeriod.getTrackGroups();
        for (int i = 0; i < renderers.length; i++) {
          Renderer renderer = renderers[i];
          TrackSelection oldSelection = oldTrackSelections.get(i);
@@ -716,7 +714,7 @@ import java.util.ArrayList;
              // can be seamless.
              Format[] formats = new Format[newSelection.length];
              for (int j = 0; j < formats.length; j++) {
-                formats[j] = groups.get(newSelection.group).getFormat(newSelection.getTrack(j));
+                formats[j] = newSelection.group.getFormat(newSelection.getTrack(j));
              }
              renderer.replaceStream(formats, readingPeriod.sampleStreams[i],
                  readingPeriod.offsetUs);
@@ -956,7 +954,6 @@ import java.util.ArrayList;
        throws ExoPlaybackException {
      enabledRenderers = new Renderer[enabledRendererCount];
      enabledRendererCount = 0;
-      TrackGroupArray trackGroups = playingPeriod.mediaPeriod.getTrackGroups();
      for (int i = 0; i < renderers.length; i++) {
        Renderer renderer = renderers[i];
        TrackSelection newSelection = playingPeriod.trackSelections.get(i);
@@ -970,7 +967,7 @@ import java.util.ArrayList;
            // Build an array of formats contained by the selection.
            Format[] formats = new Format[newSelection.length];
            for (int j = 0; j < formats.length; j++) {
-              formats[j] = trackGroups.get(newSelection.group).getFormat(newSelection.getTrack(j));
+              formats[j] = newSelection.group.getFormat(newSelection.getTrack(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
@@ -252,7 +252,7 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
      TrackSelection selection = newSelections.get(i);
      Assertions.checkState(selection.length == 1);
      Assertions.checkState(selection.getTrack(0) == 0);
-      int track = selection.group;
+      int track = tracks.indexOf(selection.group);
      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
@@ -19,8 +19,6 @@ import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
-import android.util.Pair;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.IdentityHashMap;
@@ -183,9 +181,10 @@ public final class MergingMediaPeriod implements MediaPeriod, MediaPeriod.Callba
    TrackGroup[] trackGroupArray = new TrackGroup[totalTrackGroupCount];
    int trackGroupIndex = 0;
    for (MediaPeriod period : periods) {
-      int periodTrackGroupCount = period.getTrackGroups().length;
+      TrackGroupArray periodTrackGroups = period.getTrackGroups();
+      int periodTrackGroupCount = periodTrackGroups.length;
      for (int j = 0; j < periodTrackGroupCount; j++) {
-        trackGroupArray[trackGroupIndex++] = period.getTrackGroups().get(j);
+        trackGroupArray[trackGroupIndex++] = periodTrackGroups.get(j);
      }
    }
    trackGroups = new TrackGroupArray(trackGroupArray);
@@ -218,12 +217,12 @@ public final class MergingMediaPeriod implements MediaPeriod, MediaPeriod.Callba
    // Get the subset of the new selections for the period.
    ArrayList<TrackSelection> newSelections = new ArrayList<>();
    int[] newSelectionOriginalIndices = new int[allNewSelections.size()];
+    TrackGroupArray periodTrackGroups = period.getTrackGroups();
    for (int i = 0; i < allNewSelections.size(); i++) {
      TrackSelection selection = allNewSelections.get(i);
-      Pair<MediaPeriod, Integer> periodAndGroup = getPeriodAndGroup(selection.group);
+      if (periodTrackGroups.indexOf(selection.group) != -1) {
-      if (periodAndGroup.first == period) {
        newSelectionOriginalIndices[newSelections.size()] = i;
-        newSelections.add(new TrackSelection(periodAndGroup.second, selection.getTracks()));
+        newSelections.add(selection);
      }
    }
    // Do nothing if nothing has changed, except during the first selection.
@@ -239,16 +238,4 @@ public final class MergingMediaPeriod implements MediaPeriod, MediaPeriod.Callba
    return newSelections.size() - oldStreams.size();
  }
-  private Pair<MediaPeriod, Integer> getPeriodAndGroup(int group) {
-    int totalTrackGroupCount = 0;
-    for (MediaPeriod period : periods) {
-      int periodTrackGroupCount = period.getTrackGroups().length;
-      if (group < totalTrackGroupCount + periodTrackGroupCount) {
-        return Pair.create(period, group - totalTrackGroupCount);
-      }
-      totalTrackGroupCount += periodTrackGroupCount;
-    }
-    throw new IndexOutOfBoundsException();
-  }
 }
--- a/library/src/main/java/com/google/android/exoplayer2/source/TrackGroup.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/TrackGroup.java
@@ -72,6 +72,21 @@ public final class TrackGroup {
    return formats[index];
  }
+  /**
+   * Gets the index of the track with the given format in the group.
+   *
+   * @param format The format.
+   * @return The index of the track, or -1 if no such track exists.
+   */
+  public int indexOf(Format format) {
+    for (int i = 0; i < formats.length; i++) {
+      if (format == formats[i]) {
+        return i;
+      }
+    }
+    return -1;
+  }
  @Override
  public int hashCode() {
    if (hashCode == 0) {

--- a/library/src/main/java/com/google/android/exoplayer2/source/TrackGroupArray.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/TrackGroupArray.java
@@ -50,6 +50,21 @@ public final class TrackGroupArray {
    return trackGroups[index];
  }
+  /**
+   * Gets the index of a group within the array.
+   *
+   * @param group The group.
+   * @return The index of the group, or -1 if no such group exists.
+   */
+  public int indexOf(TrackGroup group) {
+    for (int i = 0; i < length; i++) {
+      if (trackGroups[i] == group) {
+        return i;
+      }
+    }
+    return -1;
+  }
  @Override
  public int hashCode() {
    if (hashCode == 0) {

--- a/library/src/main/java/com/google/android/exoplayer2/source/dash/DashChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/dash/DashChunkSource.java
@@ -15,9 +15,9 @@
 */
 package com.google.android.exoplayer2.source.dash;
-import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.ChunkSource;
 import com.google.android.exoplayer2.source.dash.manifest.DashManifest;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Loader;
 /**
@@ -28,7 +28,7 @@ public interface DashChunkSource extends ChunkSource {
  interface Factory {
    DashChunkSource createDashChunkSource(Loader manifestLoader, DashManifest manifest,
-        int periodIndex, int adaptationSetIndex, TrackGroup trackGroup, int[] tracks,
+        int periodIndex, int adaptationSetIndex, TrackSelection trackSelection,
        long elapsedRealtimeOffsetMs);
  }

--- 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
@@ -236,12 +236,10 @@ import java.util.List;
  private ChunkSampleStream<DashChunkSource> buildSampleStream(TrackSelection selection,
      long positionUs) {
-    int[] selectedTracks = selection.getTracks();
+    int adaptationSetIndex = trackGroupAdaptationSetIndices[trackGroups.indexOf(selection.group)];
-    int adaptationSetIndex = trackGroupAdaptationSetIndices[selection.group];
    AdaptationSet adaptationSet = period.adaptationSets.get(adaptationSetIndex);
    DashChunkSource chunkSource = chunkSourceFactory.createDashChunkSource(loader, manifest, index,
-        adaptationSetIndex, trackGroups.get(selection.group), selectedTracks,
+        adaptationSetIndex, selection, elapsedRealtimeOffset);
-        elapsedRealtimeOffset);
    return new ChunkSampleStream<>(adaptationSet.type, chunkSource, this, allocator, positionUs,
        minLoadableRetryCount, eventDispatcher);
  }

--- 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
@@ -17,13 +17,11 @@ package com.google.android.exoplayer2.source.dash;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.Format.DecreasingBandwidthComparator;
 import com.google.android.exoplayer2.extractor.ChunkIndex;
 import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.extractor.mkv.MatroskaExtractor;
 import com.google.android.exoplayer2.extractor.mp4.FragmentedMp4Extractor;
 import com.google.android.exoplayer2.source.BehindLiveWindowException;
-import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.Chunk;
 import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper;
 import com.google.android.exoplayer2.source.chunk.ChunkHolder;
@@ -36,6 +34,7 @@ import com.google.android.exoplayer2.source.chunk.SingleSampleMediaChunk;
 import com.google.android.exoplayer2.source.dash.manifest.DashManifest;
 import com.google.android.exoplayer2.source.dash.manifest.RangedUri;
 import com.google.android.exoplayer2.source.dash.manifest.Representation;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.HttpDataSource.InvalidResponseCodeException;
@@ -46,7 +45,6 @@ import com.google.android.exoplayer2.util.Util;
 import android.os.SystemClock;
 import java.io.IOException;
-import java.util.Arrays;
 import java.util.List;
 /**
@@ -67,22 +65,21 @@ public class DefaultDashChunkSource implements DashChunkSource {
    @Override
    public DashChunkSource createDashChunkSource(Loader manifestLoader, DashManifest manifest,
-        int periodIndex, int adaptationSetIndex, TrackGroup trackGroup, int[] tracks,
+        int periodIndex, int adaptationSetIndex, TrackSelection trackSelection,
        long elapsedRealtimeOffsetMs) {
-      FormatEvaluator adaptiveEvaluator = tracks.length > 1
+      FormatEvaluator adaptiveEvaluator = trackSelection.length > 1
          ? formatEvaluatorFactory.createFormatEvaluator() : null;
      DataSource dataSource = dataSourceFactory.createDataSource();
     return new DefaultDashChunkSource(manifestLoader, manifest, periodIndex, adaptationSetIndex,
-         trackGroup, tracks, dataSource, adaptiveEvaluator, elapsedRealtimeOffsetMs);
+         trackSelection, dataSource, adaptiveEvaluator, elapsedRealtimeOffsetMs);
    }
  }
  private final Loader manifestLoader;
  private final int adaptationSetIndex;
-  private final TrackGroup trackGroup;
+  private final TrackSelection trackSelection;
  private final RepresentationHolder[] representationHolders;
-  private final Format[] enabledFormats;
  private final boolean[] adaptiveFormatBlacklistFlags;
  private final DataSource dataSource;
  private final FormatEvaluator adaptiveFormatEvaluator;
@@ -100,8 +97,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
   * @param manifest The initial manifest.
   * @param periodIndex The index of the period in the manifest.
   * @param adaptationSetIndex The index of the adaptation set in the period.
-   * @param trackGroup The track group corresponding to the adaptation set.
+   * @param trackSelection The track selection.
-   * @param tracks The indices of the selected tracks within the adaptation set.
   * @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
@@ -109,12 +105,12 @@ public class DefaultDashChunkSource implements DashChunkSource {
   *     as the server's unix time minus the local elapsed time. If unknown, set to 0.
   */
  public DefaultDashChunkSource(Loader manifestLoader, DashManifest manifest, int periodIndex,
-      int adaptationSetIndex, TrackGroup trackGroup, int[] tracks, DataSource dataSource,
+      int adaptationSetIndex, TrackSelection trackSelection, DataSource dataSource,
      FormatEvaluator adaptiveFormatEvaluator, long elapsedRealtimeOffsetMs) {
    this.manifestLoader = manifestLoader;
    this.manifest = manifest;
    this.adaptationSetIndex = adaptationSetIndex;
-    this.trackGroup = trackGroup;
+    this.trackSelection = trackSelection;
    this.dataSource = dataSource;
    this.adaptiveFormatEvaluator = adaptiveFormatEvaluator;
    this.elapsedRealtimeOffsetUs = elapsedRealtimeOffsetMs * 1000;
@@ -122,20 +118,14 @@ public class DefaultDashChunkSource implements DashChunkSource {
    long periodDurationUs = getPeriodDurationUs(periodIndex);
    List<Representation> representations = getRepresentations(periodIndex);
-    representationHolders = new RepresentationHolder[representations.size()];
+    representationHolders = new RepresentationHolder[trackSelection.length];
+    for (int i = 0; i < trackSelection.length; i++) {
-    for (int i = 0; i < representations.size(); i++) {
+      Representation representation = representations.get(trackSelection.getTrack(i));
-      Representation representation = representations.get(i);
      representationHolders[i] = new RepresentationHolder(periodDurationUs, representation);
    }
-    enabledFormats = new Format[tracks.length];
-    for (int i = 0; i < tracks.length; i++) {
-      enabledFormats[i] = trackGroup.getFormat(tracks[i]);
-    }
-    Arrays.sort(enabledFormats, new DecreasingBandwidthComparator());
    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.enable(enabledFormats);
+      adaptiveFormatEvaluator.enable(trackSelection.getFormats());
-      adaptiveFormatBlacklistFlags = new boolean[tracks.length];
+      adaptiveFormatBlacklistFlags = new boolean[trackSelection.length];
    } else {
      adaptiveFormatBlacklistFlags = null;
    }
@@ -147,8 +137,8 @@ public class DefaultDashChunkSource implements DashChunkSource {
      manifest = newManifest;
      long periodDurationUs = getPeriodDurationUs(periodIndex);
      List<Representation> representations = getRepresentations(periodIndex);
-      for (int i = 0; i < representationHolders.length; i++) {
+      for (int i = 0; i < trackSelection.length; i++) {
-        Representation representation = representations.get(i);
+        Representation representation = representations.get(trackSelection.getTrack(i));
        representationHolders[i].updateRepresentation(periodDurationUs, representation);
      }
    } catch (BehindLiveWindowException e) {
@@ -167,7 +157,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
  @Override
  public int getPreferredQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
-    if (fatalError != null || enabledFormats.length < 2) {
+    if (fatalError != null || trackSelection.length < 2) {
      return queue.size();
    }
    return adaptiveFormatEvaluator.evaluateQueueSize(playbackPositionUs, queue,
@@ -181,12 +171,12 @@ public class DefaultDashChunkSource implements DashChunkSource {
    }
    if (evaluation.format == null || !lastChunkWasInitialization) {
-      if (enabledFormats.length > 1) {
+      if (trackSelection.length > 1) {
        long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
        adaptiveFormatEvaluator.evaluateFormat(bufferedDurationUs, adaptiveFormatBlacklistFlags,
            evaluation);
      } else {
-        evaluation.format = enabledFormats[0];
+        evaluation.format = trackSelection.getFormat(0);
        evaluation.trigger = FormatEvaluator.TRIGGER_UNKNOWN;
        evaluation.data = null;
      }
@@ -198,7 +188,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
    }
    RepresentationHolder representationHolder =
-        representationHolders[getTrackIndex(selectedFormat)];
+        representationHolders[trackSelection.indexOf(selectedFormat)];
    Representation selectedRepresentation = representationHolder.representation;
    DashSegmentIndex segmentIndex = representationHolder.segmentIndex;
@@ -270,7 +260,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
    if (chunk instanceof InitializationChunk) {
      InitializationChunk initializationChunk = (InitializationChunk) chunk;
      RepresentationHolder representationHolder =
-          representationHolders[getTrackIndex(initializationChunk.format)];
+          representationHolders[trackSelection.indexOf(initializationChunk.format)];
      Format sampleFormat = initializationChunk.getSampleFormat();
      if (sampleFormat != null) {
        representationHolder.setSampleFormat(sampleFormat);
@@ -295,7 +285,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
        && e instanceof InvalidResponseCodeException
        && ((InvalidResponseCodeException) e).responseCode == 404) {
      RepresentationHolder representationHolder =
-          representationHolders[getTrackIndex(chunk.format)];
+          representationHolders[trackSelection.indexOf(chunk.format)];
      int lastAvailableSegmentNum = representationHolder.getLastSegmentNum();
      if (((MediaChunk) chunk).chunkIndex >= lastAvailableSegmentNum) {
        missingLastSegment = true;
@@ -368,16 +358,6 @@ public class DefaultDashChunkSource implements DashChunkSource {
    }
  }
-  private int getTrackIndex(Format format) {
-    for (int i = 0; i < trackGroup.length; i++) {
-      if (trackGroup.getFormat(i) == format) {
-        return i;
-      }
-    }
-    // Should never happen.
-    throw new IllegalStateException("Invalid format: " + format);
-  }
  private long getPeriodDurationUs(int periodIndex) {
    long durationMs = manifest.getPeriodDuration(periodIndex);
    if (durationMs == -1) {

--- 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
@@ -23,6 +23,7 @@ import com.google.android.exoplayer2.extractor.ts.AdtsExtractor;
 import com.google.android.exoplayer2.extractor.ts.PtsTimestampAdjuster;
 import com.google.android.exoplayer2.extractor.ts.TsExtractor;
 import com.google.android.exoplayer2.source.BehindLiveWindowException;
+import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.Chunk;
 import com.google.android.exoplayer2.source.chunk.ChunkHolder;
 import com.google.android.exoplayer2.source.chunk.DataChunk;
@@ -31,6 +32,7 @@ import com.google.android.exoplayer2.source.chunk.FormatEvaluator.Evaluation;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist;
 import com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistParser;
 import com.google.android.exoplayer2.source.hls.playlist.Variant;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.HttpDataSource.InvalidResponseCodeException;
@@ -47,7 +49,6 @@ import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.math.BigInteger;
 import java.util.Arrays;
-import java.util.Comparator;
 import java.util.Locale;
 /**
@@ -78,6 +79,7 @@ public class HlsChunkSource {
  private final PtsTimestampAdjusterProvider timestampAdjusterProvider;
  private final Variant[] variants;
  private final HlsMediaPlaylist[] variantPlaylists;
+  private final TrackGroup trackGroup;
  private final long[] variantLastPlaylistLoadTimesMs;
  private boolean seenFirstExternalTrackSelection;
@@ -92,7 +94,7 @@ public class HlsChunkSource {
  private byte[] encryptionIv;
  // Properties of enabled variants.
-  private Variant[] enabledVariants;
+  private TrackSelection trackSelection;
  private long[] enabledVariantBlacklistTimes;
  private boolean[] enabledVariantBlacklistFlags;
@@ -117,11 +119,15 @@ public class HlsChunkSource {
    evaluation = new Evaluation();
    variantPlaylists = new HlsMediaPlaylist[variants.length];
    variantLastPlaylistLoadTimesMs = new long[variants.length];
+    Format[] variantFormats = new Format[variants.length];
    int[] initialTrackSelection = new int[variants.length];
    for (int i = 0; i < variants.length; i++) {
+      variantFormats[i] = variants[i].format;
      initialTrackSelection[i] = i;
    }
-    selectTracksInternal(initialTrackSelection, false);
+    trackGroup = new TrackGroup(adaptiveFormatEvaluator != null, variantFormats);
+    selectTracksInternal(new TrackSelection(trackGroup, initialTrackSelection), false);
  }
  /**
@@ -137,18 +143,7 @@ public class HlsChunkSource {
  }
  /**
-   * Returns whether this source supports adaptation between its tracks.
-   *
-   * @return Whether this source supports adaptation between its tracks.
-   */
-  public boolean isAdaptive() {
-    return adaptiveFormatEvaluator != null;
-  }
-  /**
   * Returns whether this is a live playback.
-   * <p>
-   * This method should only be called after the source has been prepared.
   *
   * @return True if this is a live playback. False otherwise.
   */
@@ -158,8 +153,6 @@ public class HlsChunkSource {
  /**
   * Returns the duration of the source, or {@link C#UNSET_TIME_US} if the duration is unknown.
-   * <p>
-   * This method should only be called after the source has been prepared.
   *
   * @return The number of tracks.
   */
@@ -168,43 +161,25 @@ public class HlsChunkSource {
  }
  /**
-   * Returns the number of tracks exposed by the source.
+   * Returns the track group exposed by the source.
-   * <p>
-   * This method should only be called after the source has been prepared.
-   *
-   * @return The number of tracks.
-   */
-  public int getTrackCount() {
-    return variants.length;
-  }
-  /**
-   * Returns the format of the track at the specified index.
-   * <p>
-   * This method should only be called after the source has been prepared.
   *
-   * @param index The track index.
+   * @return The track group.
-   * @return The format of the track.
   */
-  public Format getTrackFormat(int index) {
+  public TrackGroup getTrackGroup() {
-    return variants[index].format;
+    return trackGroup;
  }
  /**
   * Selects tracks for use.
-   * <p>
-   * This method should only be called after the source has been prepared.
   *
-   * @param tracks The track indices.
+   * @param trackSelection The track selection.
   */
-  public void selectTracks(int[] tracks) {
+  public void selectTracks(TrackSelection trackSelection) {
-    selectTracksInternal(tracks, true);
+    selectTracksInternal(trackSelection, true);
  }
  /**
   * Resets the source.
-   * <p>
-   * This method should only be called after the source has been prepared.
   */
  public void reset() {
    fatalError = null;
@@ -224,10 +199,9 @@ public class HlsChunkSource {
   * @param out A holder to populate.
   */
  public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, ChunkHolder out) {
-    int previousChunkVariantIndex =
+    int previousChunkVariantIndex = previous != null ? trackGroup.indexOf(previous.format) : -1;
-        previous != null ? getVariantIndex(previous.format) : -1;
    updateFormatEvaluation(previous, playbackPositionUs);
-    int newVariantIndex = getVariantIndex(evaluation.format);
+    int newVariantIndex = trackGroup.indexOf(evaluation.format);
    boolean switchingVariant = previousChunkVariantIndex != newVariantIndex;
    HlsMediaPlaylist mediaPlaylist = variantPlaylists[newVariantIndex];
    if (mediaPlaylist == null) {
@@ -443,7 +417,7 @@ public class HlsChunkSource {
      InvalidResponseCodeException responseCodeException = (InvalidResponseCodeException) e;
      int responseCode = responseCodeException.responseCode;
      if (responseCode == 404 || responseCode == 410) {
-        int enabledVariantIndex = getEnabledVariantIndex(chunk.format);
+        int enabledVariantIndex = trackSelection.indexOf(chunk.format);
        boolean alreadyBlacklisted = enabledVariantBlacklistFlags[enabledVariantIndex];
        enabledVariantBlacklistFlags[enabledVariantIndex] = true;
        enabledVariantBlacklistTimes[enabledVariantIndex] = SystemClock.elapsedRealtime();
@@ -471,37 +445,21 @@ public class HlsChunkSource {
  // Private methods.
-  private void selectTracksInternal(int[] tracks, boolean isExternal) {
+  private void selectTracksInternal(TrackSelection trackSelection, boolean isExternal) {
+    this.trackSelection = trackSelection;
    seenFirstExternalTrackSelection |= isExternal;
-    // Construct and sort the enabled variants.
-    enabledVariants = new Variant[tracks.length];
-    for (int i = 0; i < tracks.length; i++) {
-      enabledVariants[i] = variants[tracks[i]];
-    }
-    Arrays.sort(enabledVariants, new Comparator<Variant>() {
-      private final Comparator<Format> formatComparator =
-          new Format.DecreasingBandwidthComparator();
-      @Override
-      public int compare(Variant first, Variant second) {
-        return formatComparator.compare(first.format, second.format);
-      }
-    });
    // Reset the enabled variant blacklist flags.
-    enabledVariantBlacklistTimes = new long[enabledVariants.length];
+    enabledVariantBlacklistTimes = new long[trackSelection.length];
-    enabledVariantBlacklistFlags = new boolean[enabledVariants.length];
+    enabledVariantBlacklistFlags = new boolean[trackSelection.length];
    if (!isExternal) {
      return;
    }
-    if (enabledVariants.length > 1) {
+    if (trackSelection.length > 1) {
-      Format[] formats = new Format[enabledVariants.length];
-      for (int i = 0; i < formats.length; i++) {
-        formats[i] = enabledVariants[i].format;
-      }
      // TODO[REFACTOR]: We need to disable this at some point.
+      Format[] formats = trackSelection.getFormats();
      adaptiveFormatEvaluator.enable(formats);
      if (!Util.contains(formats, evaluation.format)) {
        evaluation.format = null;
@@ -515,23 +473,23 @@ public class HlsChunkSource {
  private void updateFormatEvaluation(HlsMediaChunk previous, long playbackPositionUs) {
    clearStaleBlacklistedVariants();
    if (!seenFirstExternalTrackSelection) {
-      if (!enabledVariantBlacklistFlags[getEnabledVariantIndex(variants[0].format)]) {
+      if (!enabledVariantBlacklistFlags[trackSelection.indexOf(variants[0].format)]) {
        // Use the first variant prior to external track selection, unless it's been blacklisted.
        evaluation.format = variants[0].format;
        return;
      }
      // Try from lowest bitrate to highest.
-      for (int i = enabledVariants.length - 1; i >= 0; i--) {
+      for (int i = trackSelection.length - 1; i >= 0; i--) {
        if (!enabledVariantBlacklistFlags[i]) {
-          evaluation.format = enabledVariants[i].format;
+          evaluation.format = trackSelection.getFormat(i);
          return;
        }
      }
      // Should never happen.
      throw new IllegalStateException();
    }
-    if (enabledVariants.length == 1) {
+    if (trackSelection.length == 1) {
-      evaluation.format = enabledVariants[0].format;
+      evaluation.format = trackSelection.getFormat(0);
      return;
    }
    long bufferedDurationUs;
@@ -624,26 +582,6 @@ public class HlsChunkSource {
    }
  }
-  private int getEnabledVariantIndex(Format format) {
-    for (int i = 0; i < enabledVariants.length; i++) {
-      if (enabledVariants[i].format == format) {
-        return i;
-      }
-    }
-    // Should never happen.
-    throw new IllegalStateException("Invalid format: " + format);
-  }
-  private int getVariantIndex(Format format) {
-    for (int i = 0; i < variants.length; i++) {
-      if (variants[i].format == format) {
-        return i;
-      }
-    }
-    // Should never happen.
-    throw new IllegalStateException("Invalid format: " + format);
-  }
  // Private classes.
  private static final class MediaPlaylistChunk extends DataChunk {

--- 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
@@ -43,7 +43,6 @@ import com.google.android.exoplayer2.util.MimeTypes;
 import android.net.Uri;
 import android.os.Handler;
 import android.text.TextUtils;
-import android.util.Pair;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -429,13 +428,13 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
    }
    // Get the subset of the new selections for the wrapper.
    ArrayList<TrackSelection> newSelections = new ArrayList<>();
+    TrackGroupArray sampleStreamWrapperTrackGroups = sampleStreamWrapper.getTrackGroups();
    int[] newSelectionOriginalIndices = new int[allNewSelections.size()];
    for (int i = 0; i < allNewSelections.size(); i++) {
      TrackSelection selection = allNewSelections.get(i);
-      Pair<HlsSampleStreamWrapper, Integer> sourceAndGroup = getSourceAndGroup(selection.group);
+      if (sampleStreamWrapperTrackGroups.indexOf(selection.group) != -1) {
-      if (sourceAndGroup.first == sampleStreamWrapper) {
        newSelectionOriginalIndices[newSelections.size()] = i;
-        newSelections.add(new TrackSelection(sourceAndGroup.second, selection.getTracks()));
+        newSelections.add(selection);
      }
    }
    // Do nothing if nothing has changed, except during the first selection.
@@ -452,18 +451,6 @@ public final class HlsMediaSource implements MediaPeriod, MediaSource,
    return newSelections.size() - oldStreams.size();
  }
-  private Pair<HlsSampleStreamWrapper, Integer> getSourceAndGroup(int group) {
-    int totalTrackGroupCount = 0;
-    for (HlsSampleStreamWrapper sampleStreamWrapper : sampleStreamWrappers) {
-      int sourceTrackGroupCount = sampleStreamWrapper.getTrackGroups().length;
-      if (group < totalTrackGroupCount + sourceTrackGroupCount) {
-        return Pair.create(sampleStreamWrapper, group - totalTrackGroupCount);
-      }
-      totalTrackGroupCount += sourceTrackGroupCount;
-    }
-    throw new IndexOutOfBoundsException();
-  }
  private static boolean variantHasExplicitCodecWithPrefix(Variant variant, String prefix) {
    String codecs = variant.codecs;
    if (TextUtils.isEmpty(codecs)) {

--- 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
@@ -164,11 +164,11 @@ 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 = selection.group;
+      int group = trackGroups.indexOf(selection.group);
      int[] tracks = selection.getTracks();
      setTrackGroupEnabledState(group, true);
      if (group == primaryTrackGroupIndex) {
-        chunkSource.selectTracks(tracks);
+        chunkSource.selectTracks(new TrackSelection(chunkSource.getTrackGroup(), tracks));
      }
      newStreams[i] = new SampleStreamImpl(group);
    }
@@ -526,8 +526,8 @@ import java.util.List;
      }
    }
-    // Calculate the number of tracks that will be exposed.
+    TrackGroup chunkSourceTrackGroup = chunkSource.getTrackGroup();
-    int chunkSourceTrackCount = chunkSource.getTrackCount();
+    int chunkSourceTrackCount = chunkSourceTrackGroup.length;
    // Instantiate the necessary internal data-structures.
    primaryTrackGroupIndex = -1;
@@ -540,9 +540,9 @@ import java.util.List;
      if (i == primaryExtractorTrackIndex) {
        Format[] formats = new Format[chunkSourceTrackCount];
        for (int j = 0; j < chunkSourceTrackCount; j++) {
-          formats[j] = getSampleFormat(chunkSource.getTrackFormat(j), sampleFormat);
+          formats[j] = getSampleFormat(chunkSourceTrackGroup.getFormat(j), sampleFormat);
        }
-        trackGroups[i] = new TrackGroup(chunkSource.isAdaptive(), formats);
+        trackGroups[i] = new TrackGroup(chunkSourceTrackGroup.adaptive, formats);
        primaryTrackGroupIndex = i;
      } else {
        Format trackFormat = null;

--- 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
@@ -17,12 +17,10 @@ package com.google.android.exoplayer2.source.smoothstreaming;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.Format.DecreasingBandwidthComparator;
 import com.google.android.exoplayer2.extractor.mp4.FragmentedMp4Extractor;
 import com.google.android.exoplayer2.extractor.mp4.Track;
 import com.google.android.exoplayer2.extractor.mp4.TrackEncryptionBox;
 import com.google.android.exoplayer2.source.BehindLiveWindowException;
-import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.Chunk;
 import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper;
 import com.google.android.exoplayer2.source.chunk.ChunkHolder;
@@ -32,15 +30,14 @@ 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;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.Loader;
 import android.net.Uri;
-import android.text.TextUtils;
 import java.io.IOException;
-import java.util.Arrays;
 import java.util.List;
 /**
@@ -61,23 +58,21 @@ public class DefaultSsChunkSource implements SsChunkSource {
    @Override
    public SsChunkSource createChunkSource(Loader manifestLoader, SsManifest manifest,
-        int elementIndex, TrackGroup trackGroup, int[] tracks,
+        int elementIndex, TrackSelection trackSelection,
        TrackEncryptionBox[] trackEncryptionBoxes) {
-      FormatEvaluator adaptiveEvaluator = tracks.length > 1
+      FormatEvaluator adaptiveEvaluator = trackSelection.length > 1
          ? formatEvaluatorFactory.createFormatEvaluator() : null;
      DataSource dataSource = dataSourceFactory.createDataSource();
-      return new DefaultSsChunkSource(manifestLoader, manifest, elementIndex,
+      return new DefaultSsChunkSource(manifestLoader, manifest, elementIndex, trackSelection,
-          trackGroup, tracks, dataSource, adaptiveEvaluator,
+          dataSource, adaptiveEvaluator, trackEncryptionBoxes);
-          trackEncryptionBoxes);
    }
  }
  private final Loader manifestLoader;
  private final int elementIndex;
-  private final TrackGroup trackGroup;
+  private final TrackSelection trackSelection;
  private final ChunkExtractorWrapper[] extractorWrappers;
-  private final Format[] enabledFormats;
  private final boolean[] adaptiveFormatBlacklistFlags;
  private final DataSource dataSource;
  private final Evaluation evaluation;
@@ -92,45 +87,40 @@ public class DefaultSsChunkSource implements SsChunkSource {
   * @param manifestLoader The {@link Loader} being used to load manifests.
   * @param manifest The initial manifest.
   * @param elementIndex The index of the stream element in the manifest.
-   * @param trackGroup The track group corresponding to the stream element.
+   * @param trackSelection The track selection.
-   * @param tracks The indices of the selected tracks within the stream element.
   * @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(Loader manifestLoader, SsManifest manifest, int elementIndex,
-      TrackGroup trackGroup, int[] tracks, DataSource dataSource,
+      TrackSelection trackSelection, DataSource dataSource, FormatEvaluator adaptiveFormatEvaluator,
-      FormatEvaluator adaptiveFormatEvaluator, TrackEncryptionBox[] trackEncryptionBoxes) {
+      TrackEncryptionBox[] trackEncryptionBoxes) {
    this.manifestLoader = manifestLoader;
    this.manifest = manifest;
    this.elementIndex = elementIndex;
-    this.trackGroup = trackGroup;
+    this.trackSelection = trackSelection;
    this.dataSource = dataSource;
    this.adaptiveFormatEvaluator = adaptiveFormatEvaluator;
    this.evaluation = new Evaluation();
    StreamElement streamElement = manifest.streamElements[elementIndex];
-    Format[] formats = streamElement.formats;
-    extractorWrappers = new ChunkExtractorWrapper[formats.length];
+    extractorWrappers = new ChunkExtractorWrapper[trackSelection.length];
-    for (int j = 0; j < formats.length; j++) {
+    for (int i = 0; i < trackSelection.length; i++) {
+      int manifestTrackIndex = trackSelection.getTrack(i);
+      Format format = trackSelection.getFormat(i);
      int nalUnitLengthFieldLength = streamElement.type == C.TRACK_TYPE_VIDEO ? 4 : -1;
-      Track track = new Track(j, streamElement.type, streamElement.timescale, C.UNSET_TIME_US,
+      Track track = new Track(manifestTrackIndex, streamElement.type, streamElement.timescale,
-          manifest.durationUs, formats[j], Track.TRANSFORMATION_NONE, trackEncryptionBoxes,
+          C.UNSET_TIME_US, manifest.durationUs, format, Track.TRANSFORMATION_NONE,
-          nalUnitLengthFieldLength, null, null);
+          trackEncryptionBoxes, nalUnitLengthFieldLength, null, null);
      FragmentedMp4Extractor extractor = new FragmentedMp4Extractor(
          FragmentedMp4Extractor.FLAG_WORKAROUND_EVERY_VIDEO_FRAME_IS_SYNC_FRAME
          | FragmentedMp4Extractor.FLAG_WORKAROUND_IGNORE_TFDT_BOX, track);
-      extractorWrappers[j] = new ChunkExtractorWrapper(extractor, formats[j], false);
+      extractorWrappers[i] = new ChunkExtractorWrapper(extractor, format, false);
-    }
-    enabledFormats = new Format[tracks.length];
-    for (int i = 0; i < tracks.length; i++) {
-      enabledFormats[i] = trackGroup.getFormat(tracks[i]);
    }
-    Arrays.sort(enabledFormats, new DecreasingBandwidthComparator());
    if (adaptiveFormatEvaluator != null) {
-      adaptiveFormatEvaluator.enable(enabledFormats);
+      adaptiveFormatEvaluator.enable(trackSelection.getFormats());
-      adaptiveFormatBlacklistFlags = new boolean[tracks.length];
+      adaptiveFormatBlacklistFlags = new boolean[trackSelection.length];
    } else {
      adaptiveFormatBlacklistFlags = null;
    }
@@ -172,7 +162,7 @@ public class DefaultSsChunkSource implements SsChunkSource {
  @Override
  public int getPreferredQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
-    if (fatalError != null || enabledFormats.length < 2) {
+    if (fatalError != null || trackSelection.length < 2) {
      return queue.size();
    }
    return adaptiveFormatEvaluator.evaluateQueueSize(playbackPositionUs, queue,
@@ -185,12 +175,12 @@ public class DefaultSsChunkSource implements SsChunkSource {
      return;
    }
-    if (enabledFormats.length > 1) {
+    if (trackSelection.length > 1) {
      long bufferedDurationUs = previous != null ? (previous.endTimeUs - playbackPositionUs) : 0;
      adaptiveFormatEvaluator.evaluateFormat(bufferedDurationUs, adaptiveFormatBlacklistFlags,
          evaluation);
    } else {
-      evaluation.format = enabledFormats[0];
+      evaluation.format = trackSelection.getFormat(0);
      evaluation.trigger = FormatEvaluator.TRIGGER_UNKNOWN;
      evaluation.data = null;
    }
@@ -229,10 +219,10 @@ public class DefaultSsChunkSource implements SsChunkSource {
    long chunkEndTimeUs = chunkStartTimeUs + streamElement.getChunkDurationUs(chunkIndex);
    int currentAbsoluteChunkIndex = chunkIndex + currentManifestChunkOffset;
-    int trackGroupTrackIndex = getTrackGroupTrackIndex(trackGroup, selectedFormat);
+    int trackSelectionIndex = trackSelection.indexOf(selectedFormat);
-    ChunkExtractorWrapper extractorWrapper = extractorWrappers[trackGroupTrackIndex];
+    ChunkExtractorWrapper extractorWrapper = extractorWrappers[trackSelectionIndex];
-    int manifestTrackIndex = getManifestTrackIndex(streamElement, selectedFormat);
+    int manifestTrackIndex = trackSelection.getTrack(trackSelectionIndex);
    Uri uri = streamElement.buildRequestUri(manifestTrackIndex, chunkIndex);
    out.chunk = newMediaChunk(selectedFormat, dataSource, uri, null, currentAbsoluteChunkIndex,
@@ -259,37 +249,6 @@ public class DefaultSsChunkSource implements SsChunkSource {
  // Private methods.
-  /**
-   * Gets the index of a format in a track group, using referential equality.
-   */
-  private static int getTrackGroupTrackIndex(TrackGroup trackGroup, Format format) {
-    for (int i = 0; i < trackGroup.length; i++) {
-      if (trackGroup.getFormat(i) == format) {
-        return i;
-      }
-    }
-    // Should never happen.
-    throw new IllegalStateException("Invalid format: " + format);
-  }
-  /**
-   * Gets the index of a format in an element, using format.id equality.
-   * <p>
-   * This method will return the same index as {@link #getTrackGroupTrackIndex(TrackGroup, Format)}
-   * except in the case where a live manifest is refreshed and the ordering of the tracks in the
-   * manifest has changed.
-   */
-  private static int getManifestTrackIndex(StreamElement element, Format format) {
-    Format[] formats = element.formats;
-    for (int i = 0; i < formats.length; i++) {
-      if (TextUtils.equals(formats[i].id, format.id)) {
-        return i;
-      }
-    }
-    // Should never happen.
-    throw new IllegalStateException("Invalid format: " + format);
-  }
  private static MediaChunk newMediaChunk(Format format, DataSource dataSource, Uri uri,
      String cacheKey, int chunkIndex, long chunkStartTimeUs, long chunkEndTimeUs,
      int formatEvaluatorTrigger, Object formatEvaluatorData,

--- a/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsChunkSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsChunkSource.java
@@ -16,9 +16,9 @@
 package com.google.android.exoplayer2.source.smoothstreaming;
 import com.google.android.exoplayer2.extractor.mp4.TrackEncryptionBox;
-import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.ChunkSource;
 import com.google.android.exoplayer2.source.smoothstreaming.manifest.SsManifest;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Loader;
 /**
@@ -29,7 +29,7 @@ public interface SsChunkSource extends ChunkSource {
  interface Factory {
    SsChunkSource createChunkSource(Loader manifestLoader, SsManifest manifest, int elementIndex,
-        TrackGroup trackGroup, int[] tracks, TrackEncryptionBox[] trackEncryptionBoxes);
+        TrackSelection trackSelection, TrackEncryptionBox[] trackEncryptionBoxes);
  }

--- a/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
@@ -354,11 +354,9 @@ public final class SsMediaSource implements MediaPeriod, MediaSource,
  private ChunkSampleStream<SsChunkSource> buildSampleStream(TrackSelection selection,
      long positionUs) {
-    int[] selectedTracks = selection.getTracks();
+    int streamElementIndex = trackGroupElementIndices[trackGroups.indexOf(selection.group)];
-    int streamElementIndex = trackGroupElementIndices[selection.group];
+    SsChunkSource chunkSource = chunkSourceFactory.createChunkSource(manifestLoader, manifest,
-    SsChunkSource chunkSource = chunkSourceFactory.createChunkSource(manifestLoader,
+        streamElementIndex, selection, trackEncryptionBoxes);
-        manifest, streamElementIndex, trackGroups.get(selection.group), selectedTracks,
-        trackEncryptionBoxes);
    return new ChunkSampleStream<>(manifest.streamElements[streamElementIndex].type, chunkSource,
        this, allocator, positionUs, minLoadableRetryCount, eventDispatcher);
  }

--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
@@ -176,17 +176,18 @@ public class DefaultTrackSelector extends MappingTrackSelector {
        : RendererCapabilities.ADAPTIVE_SEAMLESS;
    boolean allowMixedMimeTypes = allowMixedMimeAdaptiveness
        && (rendererCapabilities.supportsMixedMimeTypeAdaptation() & requiredAdaptiveSupport) != 0;
-    int largestAdaptiveGroup = -1;
+    TrackGroup largestAdaptiveGroup = null;
    int[] largestAdaptiveGroupTracks = NO_TRACKS;
    for (int i = 0; i < trackGroups.length; i++) {
-      int[] adaptiveTracks = getAdaptiveTracksOfGroup(trackGroups.get(i), formatSupport[i],
+      TrackGroup trackGroup = trackGroups.get(i);
+      int[] adaptiveTracks = getAdaptiveTracksOfGroup(trackGroup, formatSupport[i],
          allowMixedMimeTypes, requiredAdaptiveSupport, maxVideoWidth, maxVideoHeight);
      if (adaptiveTracks.length > largestAdaptiveGroupTracks.length) {
-        largestAdaptiveGroup = i;
+        largestAdaptiveGroup = trackGroup;
        largestAdaptiveGroupTracks = adaptiveTracks;
      }
    }
-    if (largestAdaptiveGroup != -1) {
+    if (largestAdaptiveGroup != null) {
      return new TrackSelection(largestAdaptiveGroup, largestAdaptiveGroupTracks);
    }
@@ -197,7 +198,7 @@ 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(groupIndex, trackIndex);
+          return new TrackSelection(trackGroup, trackIndex);
        }
      }
    }
@@ -267,7 +268,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
  private static TrackSelection selectSmallestSupportedVideoTrack(TrackGroupArray trackGroups,
      int[][] formatSupport) {
    int smallestPixelCount = Integer.MAX_VALUE;
-    int trackGroupIndexSelection = -1;
+    TrackGroup trackGroupSelection = null;
    int trackIndexSelection = -1;
    for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
      TrackGroup trackGroup = trackGroups.get(groupIndex);
@@ -279,13 +280,13 @@ public class DefaultTrackSelector extends MappingTrackSelector {
            && isSupportedVideoTrack(trackFormatSupport[trackIndex], format, Integer.MAX_VALUE,
                Integer.MAX_VALUE)) {
          smallestPixelCount = pixelCount;
-          trackGroupIndexSelection = groupIndex;
+          trackGroupSelection = trackGroup;
          trackIndexSelection = trackIndex;
        }
      }
    }
-    return trackIndexSelection != -1
+    return trackGroupSelection != null
-        ? new TrackSelection(trackGroupIndexSelection, trackIndexSelection) : null;
+        ? new TrackSelection(trackGroupSelection, trackIndexSelection) : null;
  }
  private static boolean isSupportedVideoTrack(int formatSupport, Format format, int maxVideoWidth,
@@ -305,7 +306,7 @@ 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(groupIndex, trackIndex);
+            return new TrackSelection(trackGroup, trackIndex);
          }
        }
      }
@@ -318,7 +319,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
  private static TrackSelection selectTrackForTextRenderer(TrackGroupArray trackGroups,
      int[][] formatSupport, String preferredLanguage) {
-    int firstForcedGroup = -1;
+    TrackGroup firstForcedGroup = null;
    int firstForcedTrack = -1;
    for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
      TrackGroup trackGroup = trackGroups.get(groupIndex);
@@ -327,17 +328,17 @@ public class DefaultTrackSelector extends MappingTrackSelector {
        if (isSupported(trackFormatSupport[trackIndex])
            && (trackGroup.getFormat(trackIndex).selectionFlags
                & Format.SELECTION_FLAG_FORCED) != 0) {
-          if (firstForcedGroup == -1) {
+          if (firstForcedGroup == null) {
-            firstForcedGroup = groupIndex;
+            firstForcedGroup = trackGroup;
            firstForcedTrack = trackIndex;
          }
          if (formatHasLanguage(trackGroup.getFormat(trackIndex), preferredLanguage)) {
-            return new TrackSelection(groupIndex, trackIndex);
+            return new TrackSelection(trackGroup, trackIndex);
          }
        }
      }
    }
-    return firstForcedGroup != -1 ? new TrackSelection(firstForcedGroup, firstForcedTrack) : null;
+    return firstForcedGroup != null ? new TrackSelection(firstForcedGroup, firstForcedTrack) : null;
  }
  // General track selection methods.
@@ -349,7 +350,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
      int[] trackFormatSupport = formatSupport[groupIndex];
      for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
        if (isSupported(trackFormatSupport[trackIndex])) {
-          return new TrackSelection(groupIndex, trackIndex);
+          return new TrackSelection(trackGroup, trackIndex);
        }
      }
    }

--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/MappingTrackSelector.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/MappingTrackSelector.java
@@ -272,39 +272,26 @@ public abstract class MappingTrackSelector extends TrackSelector {
    TrackGroupArray unassociatedTrackGroupArray = new TrackGroupArray(Arrays.copyOf(
        rendererTrackGroups[rendererCapabilities.length], unassociatedTrackGroupCount));
-    TrackSelection[] rendererTrackSelections = selectTracks(rendererCapabilities,
+    TrackSelection[] trackSelections = selectTracks(rendererCapabilities, rendererTrackGroupArrays,
-        rendererTrackGroupArrays, rendererFormatSupports);
+        rendererFormatSupports);
    // Apply track disabling and overriding.
    for (int i = 0; i < rendererCapabilities.length; i++) {
      if (rendererDisabledFlags.get(i)) {
-        rendererTrackSelections[i] = null;
+        trackSelections[i] = null;
      } else {
        Map<TrackGroupArray, TrackSelection> override = trackSelectionOverrides.get(i);
        TrackSelection overrideSelection = override == null ? null
            : override.get(rendererTrackGroupArrays[i]);
        if (overrideSelection != null) {
-          rendererTrackSelections[i] = overrideSelection;
+          trackSelections[i] = overrideSelection;
        }
      }
    }
-    // The track selections above index into the track group arrays associated to each renderer,
-    // and not to the original track groups passed to this method. Build the corresponding track
-    // selections into the original track groups to pass back as the final selection.
-    TrackSelection[] trackSelections = new TrackSelection[rendererCapabilities.length];
-    for (int i = 0; i < rendererCapabilities.length; i++) {
-      TrackSelection selection = rendererTrackSelections[i];
-      if (selection != null) {
-        TrackGroup group = rendererTrackGroupArrays[i].get(selection.group);
-        int originalGroupIndex = findGroupInGroupArray(trackGroups, group);
-        trackSelections[i] = new TrackSelection(originalGroupIndex, selection.getTracks());
-      }
-    }
    // Package up the track information and selections.
    TrackSelectionArray trackSelectionArray = new TrackSelectionArray(trackSelections);
-    TrackInfo trackInfo = new TrackInfo(rendererTrackGroupArrays, rendererTrackSelections,
+    TrackInfo trackInfo = new TrackInfo(rendererTrackGroupArrays, trackSelections,
        mixedMimeTypeAdaptationSupport, rendererFormatSupports, unassociatedTrackGroupArray);
    return Pair.<TrackSelectionArray, Object>create(trackSelectionArray, trackInfo);
  }
@@ -403,23 +390,6 @@ public abstract class MappingTrackSelector extends TrackSelector {
    return mixedMimeTypeAdaptationSupport;
  }
-  /**
-   * Finds the specified group in a group array, using referential equality.
-   *
-   * @param groupArray The group array to search.
-   * @param group The group to search for.
-   * @return The index of the group in the group array.
-   * @throws IllegalStateException If the group was not found.
-   */
-  private static int findGroupInGroupArray(TrackGroupArray groupArray, TrackGroup group) {
-    for (int i = 0; i < groupArray.length; i++) {
-      if (groupArray.get(i) == group) {
-        return i;
-      }
-    }
-    throw new IllegalStateException();
-  }
  private void notifyTrackInfoChanged(final TrackInfo trackInfo) {
    if (eventHandler != null) {
      eventHandler.post(new Runnable() {

--- a/library/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java
+++ b/library/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java
@@ -15,44 +15,93 @@
 */
 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 java.util.Arrays;
 /**
- * Defines a track selection.
+ * A track selection, consisting of a {@link TrackGroup} and a selected subset of the tracks within
+ * it. The selected tracks are exposed in order of decreasing bandwidth.
 */
 public final class TrackSelection {
  /**
-   * The index of the selected {@link TrackGroup}.
+   * The selected {@link TrackGroup}.
   */
-  public final int group;
+  public final TrackGroup group;
  /**
   * The number of selected tracks within the {@link TrackGroup}. Always greater than zero.
   */
  public final int length;
  private final int[] tracks;
+  private final Format[] formats;
  // Lazily initialized hashcode.
  private int hashCode;
  /**
-   * @param group The index of the {@link TrackGroup}.
+   * @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.
+   *     null or empty. May be in any order.
   */
-  public TrackSelection(int group, int... tracks) {
+  public TrackSelection(TrackGroup group, int... tracks) {
    Assertions.checkState(tracks.length > 0);
-    this.group = group;
+    this.group = Assertions.checkNotNull(group);
-    this.tracks = tracks;
    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]);
+    }
+  }
+  /**
+   * Gets the format of the track at a given index in the selection.
+   *
+   * @param index The index in the selection.
+   * @return The format of the selected track.
+   */
+  public Format getFormat(int index) {
+    return formats[index];
+  }
+  /**
+   * Gets a copy of the formats of the selected tracks.
+   *
+   * @return The track formats.
+   */
+  public Format[] getFormats() {
+    return formats.clone();
+  }
+  /**
+   * Gets the index in the selection of the track with the specified format.
+   *
+   * @param format The format.
+   * @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) {
+    for (int i = 0; i < length; i++) {
+      if (formats[i] == format) {
+        return i;
+      }
+    }
+    return -1;
  }
  /**
-   * Gets the index of the selected track at a given index in the selection.
+   * Gets 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.
@@ -62,7 +111,7 @@ public final class TrackSelection {
  }
  /**
-   * Gets a copy of the individual track indices.
+   * Gets a copy of the selected tracks in the track group.
   *
   * @return The track indices.
   */
@@ -71,24 +120,25 @@ public final class TrackSelection {
  }
  /**
-   * Gets whether a given track index is included in the selection.
+   * Gets the index in the selection of the track with the specified index in the track group.
   *
-   * @param trackIndex The track index.
+   * @param trackIndex The index in the track group.
-   * @return True if the index is included in the selection. False otherwise.
+   * @return The index in the selection, or -1 if the track with the specified index is not part of
+   *     the selection.
   */
-  public boolean containsTrack(int trackIndex) {
+  public int indexOf(int trackIndex) {
    for (int i = 0; i < length; i++) {
      if (tracks[i] == trackIndex) {
-        return true;
+        return i;
      }
    }
-    return false;
+    return -1;
  }
  @Override
  public int hashCode() {
    if (hashCode == 0) {
-      hashCode = 31 * group + Arrays.hashCode(tracks);
+      hashCode = 31 * System.identityHashCode(group) + Arrays.hashCode(tracks);
    }
    return hashCode;
  }

--- 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
@@ -826,11 +826,13 @@ 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(0,
+      selections[VIDEO_RENDERER_INDEX] = new TrackSelection(
+          rendererTrackGroupArrays[VIDEO_RENDERER_INDEX].get(0),
          getTrackIndices(rendererTrackGroupArrays[VIDEO_RENDERER_INDEX].get(0),
              rendererFormatSupports[VIDEO_RENDERER_INDEX][0], videoFormatIds,
              canIncludeAdditionalVideoFormats));
-      selections[AUDIO_RENDERER_INDEX] = new TrackSelection(0,
+      selections[AUDIO_RENDERER_INDEX] = new TrackSelection(
+          rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].get(0),
          getTrackIndices(rendererTrackGroupArrays[AUDIO_RENDERER_INDEX].get(0),
              rendererFormatSupports[AUDIO_RENDERER_INDEX][0], audioFormatIds, false));
      includedAdditionalVideoFormats =