Split DashMediaSource MediaPeriod implementation into DashMediaPeriod and support multiple periods.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127315877

library/src/main/java/com/google/android/exoplayer2/source/dash/DashChunkSource.java

@@ -34,9 +34,7 @@ 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;
-import com.google.android.exoplayer2.source.dash.mpd.AdaptationSet;
 import com.google.android.exoplayer2.source.dash.mpd.MediaPresentationDescription;
-import com.google.android.exoplayer2.source.dash.mpd.Period;
 import com.google.android.exoplayer2.source.dash.mpd.RangedUri;
 import com.google.android.exoplayer2.source.dash.mpd.Representation;
 import com.google.android.exoplayer2.upstream.DataSource;
@@ -84,11 +82,11 @@ public class DashChunkSource implements ChunkSource {
    * @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. It unknown, set to 0.
+   *     as the server's unix time minus the local elapsed time. If unknown, set to 0.
    */
   public DashChunkSource(Loader manifestLoader, MediaPresentationDescription manifest,
       int adaptationSetIndex, TrackGroup trackGroup, int[] tracks, DataSource dataSource,
-      FormatEvaluator adaptiveFormatEvaluator, long elapsedRealtimeOffsetMs) {
+      FormatEvaluator adaptiveFormatEvaluator, long elapsedRealtimeOffsetMs, int index) {
     this.manifestLoader = manifestLoader;
     this.manifest = manifest;
     this.adaptationSetIndex = adaptationSetIndex;
@@ -98,12 +96,10 @@ public class DashChunkSource implements ChunkSource {
     this.elapsedRealtimeOffsetUs = elapsedRealtimeOffsetMs * 1000;
     this.evaluation = new Evaluation();
 
-    Period period = manifest.getPeriod(0);
+    long periodDurationUs = getPeriodDurationUs(index);
-    long periodDurationUs = getPeriodDurationUs(manifest, 0);
+    List<Representation> representations = getRepresentations(index);
-    AdaptationSet adaptationSet = period.adaptationSets.get(adaptationSetIndex);
-
-    List<Representation> representations = adaptationSet.representations;
     representationHolders = new RepresentationHolder[representations.size()];
+
     for (int i = 0; i < representations.size(); i++) {
       Representation representation = representations.get(i);
       representationHolders[i] = new RepresentationHolder(periodDurationUs, representation);
@@ -121,12 +117,11 @@ public class DashChunkSource implements ChunkSource {
     }
   }
 
-  public void updateManifest(MediaPresentationDescription newManifest) {
+  public void updateManifest(MediaPresentationDescription newManifest, int index) {
     try {
       manifest = newManifest;
-      long periodDurationUs = getPeriodDurationUs(manifest, 0);
+      long periodDurationUs = getPeriodDurationUs(index);
-      List<Representation> representations = manifest.getPeriod(0).adaptationSets
+      List<Representation> representations = getRepresentations(index);
-          .get(adaptationSetIndex).representations;
       for (int i = 0; i < representationHolders.length; i++) {
         Representation representation = representations.get(i);
         representationHolders[i].updateRepresentation(periodDurationUs, representation);
@@ -136,6 +131,10 @@ public class DashChunkSource implements ChunkSource {
     }
   }
 
+  private List<Representation> getRepresentations(int index) {
+    return manifest.getPeriod(index).adaptationSets.get(adaptationSetIndex).representations;
+  }
+
   // ChunkSource implementation.
 
   @Override
@@ -356,7 +355,7 @@ public class DashChunkSource implements ChunkSource {
     throw new IllegalStateException("Invalid format: " + format);
   }
 
-  private static long getPeriodDurationUs(MediaPresentationDescription manifest, int index) {
+  private long getPeriodDurationUs(int index) {
     long durationMs = manifest.getPeriodDuration(index);
     if (durationMs == -1) {
       return C.UNSET_TIME_US;

library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaPeriod.java

@@ -0,0 +1,265 @@
+/*
+ * 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.source.dash;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.source.AdaptiveMediaSourceEventListener.EventDispatcher;
+import com.google.android.exoplayer2.source.CompositeSequenceableLoader;
+import com.google.android.exoplayer2.source.MediaPeriod;
+import com.google.android.exoplayer2.source.SampleStream;
+import com.google.android.exoplayer2.source.SequenceableLoader;
+import com.google.android.exoplayer2.source.TrackGroup;
+import com.google.android.exoplayer2.source.TrackGroupArray;
+import com.google.android.exoplayer2.source.chunk.ChunkSampleStream;
+import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
+import com.google.android.exoplayer2.source.dash.mpd.AdaptationSet;
+import com.google.android.exoplayer2.source.dash.mpd.MediaPresentationDescription;
+import com.google.android.exoplayer2.source.dash.mpd.Period;
+import com.google.android.exoplayer2.source.dash.mpd.Representation;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
+import com.google.android.exoplayer2.upstream.Allocator;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
+import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.DataSourceFactory;
+import com.google.android.exoplayer2.upstream.Loader;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * A DASH {@link MediaPeriod}.
+ */
+/* package */ final class DashMediaPeriod implements MediaPeriod,
+    SequenceableLoader.Callback<ChunkSampleStream<DashChunkSource>> {
+
+  private final Loader loader;
+  private final DataSourceFactory dataSourceFactory;
+  private final BandwidthMeter bandwidthMeter;
+  private final EventDispatcher eventDispatcher;
+
+  private ChunkSampleStream<DashChunkSource>[] sampleStreams;
+  private CompositeSequenceableLoader sequenceableLoader;
+  private Callback callback;
+  private Allocator allocator;
+  private long durationUs;
+  private TrackGroupArray trackGroups;
+  private int[] trackGroupAdaptationSetIndices;
+  private MediaPresentationDescription manifest;
+  private int index;
+  private int minLoadableRetryCount;
+  private long elapsedRealtimeOffset;
+  private Period period;
+
+  public DashMediaPeriod(MediaPresentationDescription manifest, int index,
+      DataSourceFactory dataSourceFactory, BandwidthMeter bandwidthMeter,
+      int minLoadableRetryCount, EventDispatcher eventDispatcher, long elapsedRealtimeOffset,
+      Loader loader) {
+    this.manifest = manifest;
+    this.index = index;
+    this.dataSourceFactory = dataSourceFactory;
+    this.bandwidthMeter = bandwidthMeter;
+    this.minLoadableRetryCount = minLoadableRetryCount;
+    this.eventDispatcher = eventDispatcher;
+    this.elapsedRealtimeOffset = elapsedRealtimeOffset;
+    this.loader = loader;
+    period = manifest.getPeriod(index);
+    durationUs = manifest.dynamic ? C.UNSET_TIME_US : manifest.getPeriodDuration(index) * 1000;
+  }
+
+  public void updateManifest(MediaPresentationDescription manifest, int index) {
+    this.manifest = manifest;
+    this.index = index;
+    period = manifest.getPeriod(index);
+    if (sampleStreams != null) {
+      for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+        sampleStream.getChunkSource().updateManifest(manifest, index);
+      }
+      callback.onContinueLoadingRequested(this);
+    }
+  }
+
+  // MediaPeriod implementation.
+
+  @Override
+  public void prepare(Callback callback, Allocator allocator, long positionUs) {
+    this.callback = callback;
+    this.allocator = allocator;
+    sampleStreams = newSampleStreamArray(0);
+    sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
+    buildTrackGroups();
+    callback.onPeriodPrepared(this);
+  }
+
+  @Override
+  public void maybeThrowPrepareError() throws IOException {
+    loader.maybeThrowError();
+  }
+
+  @Override
+  public long getDurationUs() {
+    return durationUs;
+  }
+
+  @Override
+  public TrackGroupArray getTrackGroups() {
+    return trackGroups;
+  }
+
+  @Override
+  public SampleStream[] selectTracks(List<SampleStream> oldStreams,
+      List<TrackSelection> newSelections, long positionUs) {
+    int newEnabledSourceCount = sampleStreams.length + newSelections.size() - oldStreams.size();
+    ChunkSampleStream<DashChunkSource>[] newSampleStreams =
+        newSampleStreamArray(newEnabledSourceCount);
+    int newEnabledSourceIndex = 0;
+
+    // Iterate over currently enabled streams, either releasing them or adding them to the new
+    // list.
+    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+      if (oldStreams.contains(sampleStream)) {
+        sampleStream.release();
+      } else {
+        newSampleStreams[newEnabledSourceIndex++] = sampleStream;
+      }
+    }
+
+    // Instantiate and return new streams.
+    SampleStream[] streamsToReturn = new SampleStream[newSelections.size()];
+    for (int i = 0; i < newSelections.size(); i++) {
+      newSampleStreams[newEnabledSourceIndex] =
+          buildSampleStream(newSelections.get(i), positionUs);
+      streamsToReturn[i] = newSampleStreams[newEnabledSourceIndex];
+      newEnabledSourceIndex++;
+    }
+
+    sampleStreams = newSampleStreams;
+    sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
+    return streamsToReturn;
+  }
+
+  @Override
+  public boolean continueLoading(long positionUs) {
+    return sequenceableLoader.continueLoading(positionUs);
+  }
+
+  @Override
+  public long getNextLoadPositionUs() {
+    return sequenceableLoader.getNextLoadPositionUs();
+  }
+
+  @Override
+  public long readDiscontinuity() {
+    return C.UNSET_TIME_US;
+  }
+
+  @Override
+  public long getBufferedPositionUs() {
+    long bufferedPositionUs = Long.MAX_VALUE;
+    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+      long rendererBufferedPositionUs = sampleStream.getBufferedPositionUs();
+      if (rendererBufferedPositionUs != C.END_OF_SOURCE_US) {
+        bufferedPositionUs = Math.min(bufferedPositionUs, rendererBufferedPositionUs);
+      }
+    }
+    return bufferedPositionUs == Long.MAX_VALUE ? C.END_OF_SOURCE_US : bufferedPositionUs;
+  }
+
+  @Override
+  public long seekToUs(long positionUs) {
+    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+      sampleStream.seekToUs(positionUs);
+    }
+    return positionUs;
+  }
+
+  @Override
+  public void release() {
+    if (sampleStreams != null) {
+      for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+        sampleStream.release();
+      }
+      sampleStreams = null;
+    }
+    sequenceableLoader = null;
+    callback = null;
+    allocator = null;
+    durationUs = 0;
+    trackGroups = null;
+    trackGroupAdaptationSetIndices = null;
+  }
+
+  // SequenceableLoader.Callback implementation.
+
+  @Override
+  public void onContinueLoadingRequested(ChunkSampleStream<DashChunkSource> sampleStream) {
+    callback.onContinueLoadingRequested(this);
+  }
+
+  // Internal methods.
+
+  private void buildTrackGroups() {
+    int trackGroupCount = 0;
+    trackGroupAdaptationSetIndices = new int[period.adaptationSets.size()];
+    TrackGroup[] trackGroupArray = new TrackGroup[period.adaptationSets.size()];
+    for (int i = 0; i < period.adaptationSets.size(); i++) {
+      AdaptationSet adaptationSet = period.adaptationSets.get(i);
+      int adaptationSetType = adaptationSet.type;
+      List<Representation> representations = adaptationSet.representations;
+      if (!representations.isEmpty() && (adaptationSetType == C.TRACK_TYPE_AUDIO
+          || adaptationSetType == C.TRACK_TYPE_VIDEO || adaptationSetType == C.TRACK_TYPE_TEXT)) {
+        Format[] formats = new Format[representations.size()];
+        for (int j = 0; j < formats.length; j++) {
+          formats[j] = representations.get(j).format;
+        }
+        trackGroupAdaptationSetIndices[trackGroupCount] = i;
+        boolean adaptive = adaptationSetType == C.TRACK_TYPE_VIDEO;
+        trackGroupArray[trackGroupCount++] = new TrackGroup(adaptive, formats);
+      }
+    }
+    if (trackGroupCount < trackGroupArray.length) {
+      trackGroupAdaptationSetIndices = Arrays.copyOf(trackGroupAdaptationSetIndices,
+          trackGroupCount);
+      trackGroupArray = Arrays.copyOf(trackGroupArray, trackGroupCount);
+    }
+    trackGroups = new TrackGroupArray(trackGroupArray);
+  }
+
+  private ChunkSampleStream<DashChunkSource> buildSampleStream(TrackSelection selection,
+      long positionUs) {
+    int[] selectedTracks = selection.getTracks();
+    FormatEvaluator adaptiveEvaluator = selectedTracks.length > 1
+        ? new FormatEvaluator.AdaptiveEvaluator(bandwidthMeter) : null;
+    int adaptationSetIndex = trackGroupAdaptationSetIndices[selection.group];
+    AdaptationSet adaptationSet = period.adaptationSets.get(
+        adaptationSetIndex);
+    int adaptationSetType = adaptationSet.type;
+    DataSource dataSource =
+        dataSourceFactory.createDataSource(bandwidthMeter);
+    DashChunkSource chunkSource = new DashChunkSource(loader, manifest, adaptationSetIndex,
+        trackGroups.get(selection.group), selectedTracks, dataSource, adaptiveEvaluator,
+        elapsedRealtimeOffset, index);
+    return new ChunkSampleStream<>(adaptationSetType, chunkSource, this, allocator, positionUs,
+        minLoadableRetryCount, eventDispatcher);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static ChunkSampleStream<DashChunkSource>[] newSampleStreamArray(int length) {
+    return new ChunkSampleStream[length];
+  }
+
+}

library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java

@@ -16,34 +16,19 @@
 package com.google.android.exoplayer2.source.dash;
 
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.source.AdaptiveMediaSourceEventListener;
 import com.google.android.exoplayer2.source.AdaptiveMediaSourceEventListener.EventDispatcher;
-import com.google.android.exoplayer2.source.CompositeSequenceableLoader;
 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.SequenceableLoader;
-import com.google.android.exoplayer2.source.TrackGroup;
-import com.google.android.exoplayer2.source.TrackGroupArray;
-import com.google.android.exoplayer2.source.chunk.ChunkSampleStream;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator;
-import com.google.android.exoplayer2.source.chunk.FormatEvaluator.AdaptiveEvaluator;
-import com.google.android.exoplayer2.source.dash.mpd.AdaptationSet;
 import com.google.android.exoplayer2.source.dash.mpd.MediaPresentationDescription;
 import com.google.android.exoplayer2.source.dash.mpd.MediaPresentationDescriptionParser;
-import com.google.android.exoplayer2.source.dash.mpd.Period;
-import com.google.android.exoplayer2.source.dash.mpd.Representation;
 import com.google.android.exoplayer2.source.dash.mpd.UtcTimingElement;
-import com.google.android.exoplayer2.trackselection.TrackSelection;
-import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSourceFactory;
 import com.google.android.exoplayer2.upstream.Loader;
 import com.google.android.exoplayer2.upstream.ParsingLoadable;
-import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 
 import android.net.Uri;
@@ -57,16 +42,13 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
-import java.util.Arrays;
-import java.util.List;
 import java.util.Locale;
 import java.util.TimeZone;
 
 /**
  * A DASH {@link MediaSource}.
  */
-public final class DashMediaSource implements MediaPeriod, MediaSource,
+public final class DashMediaSource implements MediaSource {
-    SequenceableLoader.Callback<ChunkSampleStream<DashChunkSource>> {
 
   /**
    * The default minimum number of times to retry loading data prior to failing.
@@ -84,22 +66,14 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
 
   private DataSource dataSource;
   private Loader loader;
-  private ChunkSampleStream<DashChunkSource>[] sampleStreams;
-  private CompositeSequenceableLoader sequenceableLoader;
 
   private Uri manifestUri;
   private long manifestLoadStartTimestamp;
   private long manifestLoadEndTimestamp;
   private MediaPresentationDescription manifest;
-
-  private Callback callback;
-  private Allocator allocator;
   private Handler manifestRefreshHandler;
-  private boolean prepared;
+  private DashMediaPeriod[] periods;
-  private long durationUs;
   private long elapsedRealtimeOffset;
-  private TrackGroupArray trackGroups;
-  private int[] trackGroupAdaptationSetIndices;
 
   public DashMediaSource(Uri manifestUri, DataSourceFactory dataSourceFactory,
       BandwidthMeter bandwidthMeter, Handler eventHandler,
@@ -118,29 +92,14 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
     eventDispatcher = new EventDispatcher(eventHandler, eventListener);
     manifestParser = new MediaPresentationDescriptionParser();
     manifestCallback = new ManifestCallback();
+    // TODO: Remove this call when prepare() is a part of MediaSource.
+    prepare(dataSourceFactory);
   }
 
   // MediaSource implementation.
 
-  @Override
+  // TODO @Override
-  public int getPeriodCount() {
+  public void prepare(DataSourceFactory dataSourceFactory) {
-    return 1;
-  }
-
-  @Override
-  public MediaPeriod createPeriod(int index) {
-    Assertions.checkArgument(index == 0);
-    return this;
-  }
-
-  // MediaPeriod implementation.
-
-  @Override
-  public void prepare(Callback callback, Allocator allocator, long positionUs) {
-    this.callback = callback;
-    this.allocator = allocator;
-    sampleStreams = newSampleStreamArray(0);
-    sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
     dataSource = dataSourceFactory.createDataSource();
     loader = new Loader("Loader:DashMediaSource");
     manifestRefreshHandler = new Handler();
@@ -148,120 +107,36 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
   }
 
   @Override
-  public void maybeThrowPrepareError() throws IOException {
+  public int getPeriodCount() {
-    loader.maybeThrowError();
+    if (manifest == null) {
-  }
+      return UNKNOWN_PERIOD_COUNT;
-
-  @Override
-  public long getDurationUs() {
-    return durationUs;
-  }
-
-  @Override
-  public TrackGroupArray getTrackGroups() {
-    return trackGroups;
-  }
-
-  @Override
-  public SampleStream[] selectTracks(List<SampleStream> oldStreams,
-      List<TrackSelection> newSelections, long positionUs) {
-    int newEnabledSourceCount = sampleStreams.length + newSelections.size() - oldStreams.size();
-    ChunkSampleStream<DashChunkSource>[] newSampleStreams =
-        newSampleStreamArray(newEnabledSourceCount);
-    int newEnabledSourceIndex = 0;
-
-    // Iterate over currently enabled streams, either releasing them or adding them to the new list.
-    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
-      if (oldStreams.contains(sampleStream)) {
-        sampleStream.release();
-      } else {
-        newSampleStreams[newEnabledSourceIndex++] = sampleStream;
-      }
     }
+    return manifest.getPeriodCount();
+  }
 
-    // Instantiate and return new streams.
+  @Override
-    SampleStream[] streamsToReturn = new SampleStream[newSelections.size()];
+  public MediaPeriod createPeriod(int index) {
-    for (int i = 0; i < newSelections.size(); i++) {
+    if (periods == null) {
-      newSampleStreams[newEnabledSourceIndex] = buildSampleStream(newSelections.get(i), positionUs);
+      return null;
-      streamsToReturn[i] = newSampleStreams[newEnabledSourceIndex];
-      newEnabledSourceIndex++;
     }
-
+    return periods[index];
-    sampleStreams = newSampleStreams;
-    sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
-    return streamsToReturn;
   }
 
-  @Override
+  // TODO @Override
-  public boolean continueLoading(long positionUs) {
-    return sequenceableLoader.continueLoading(positionUs);
-  }
-
-  @Override
-  public long getNextLoadPositionUs() {
-    return sequenceableLoader.getNextLoadPositionUs();
-  }
-
-  @Override
-  public long readDiscontinuity() {
-    return C.UNSET_TIME_US;
-  }
-
-  @Override
-  public long getBufferedPositionUs() {
-    long bufferedPositionUs = Long.MAX_VALUE;
-    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
-      long rendererBufferedPositionUs = sampleStream.getBufferedPositionUs();
-      if (rendererBufferedPositionUs != C.END_OF_SOURCE_US) {
-        bufferedPositionUs = Math.min(bufferedPositionUs, rendererBufferedPositionUs);
-      }
-    }
-    return bufferedPositionUs == Long.MAX_VALUE ? C.END_OF_SOURCE_US : bufferedPositionUs;
-  }
-
-  @Override
-  public long seekToUs(long positionUs) {
-    for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
-      sampleStream.seekToUs(positionUs);
-    }
-    return positionUs;
-  }
-
-  @Override
   public void release() {
     dataSource = null;
     if (loader != null) {
       loader.release();
       loader = null;
     }
-    if (sampleStreams != null) {
-      for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
-        sampleStream.release();
-      }
-      sampleStreams = null;
-    }
-    sequenceableLoader = null;
     manifestLoadStartTimestamp = 0;
     manifestLoadEndTimestamp = 0;
     manifest = null;
-    callback = null;
-    allocator = null;
     if (manifestRefreshHandler != null) {
       manifestRefreshHandler.removeCallbacksAndMessages(null);
       manifestRefreshHandler = null;
     }
-    prepared = false;
-    durationUs = 0;
     elapsedRealtimeOffset = 0;
-    trackGroups = null;
-    trackGroupAdaptationSetIndices = null;
-  }
-
-  // SequenceableLoader.Callback implementation.
-
-  @Override
-  public void onContinueLoadingRequested(ChunkSampleStream<DashChunkSource> sampleStream) {
-    callback.onContinueLoadingRequested(this);
   }
 
   // Loadable callbacks.
@@ -276,20 +151,17 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
     if (manifest.location != null) {
       manifestUri = manifest.location;
     }
-    if (!prepared) {
+
-      durationUs = manifest.dynamic ? C.UNSET_TIME_US : manifest.getPeriodDuration(0) * 1000;
+    if (periods == null) {
-      buildTrackGroups(manifest);
       if (manifest.utcTiming != null) {
         resolveUtcTimingElement(manifest.utcTiming);
       } else {
         finishPrepare();
       }
     } else {
-      for (ChunkSampleStream<DashChunkSource> sampleStream : sampleStreams) {
+      for (int i = 0; i < periods.length; i++) {
-        sampleStream.getChunkSource().updateManifest(manifest);
+        periods[i].updateManifest(manifest, i);
       }
-      callback.onContinueLoadingRequested(this);
-      scheduleManifestRefresh();
     }
   }
 
@@ -371,8 +243,12 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
   }
 
   private void finishPrepare() {
-    prepared = true;
+    int periodCount = manifest.getPeriodCount();
-    callback.onPeriodPrepared(this);
+    periods = new DashMediaPeriod[periodCount];
+    for (int i = 0; i < periodCount; i++) {
+      periods[i] = new DashMediaPeriod(manifest, i, dataSourceFactory, bandwidthMeter,
+          minLoadableRetryCount, eventDispatcher, elapsedRealtimeOffset, loader);
+    }
     scheduleManifestRefresh();
   }
 
@@ -404,56 +280,6 @@ public final class DashMediaSource implements MediaPeriod, MediaSource,
     eventDispatcher.loadStarted(loadable.dataSpec, loadable.type, elapsedRealtimeMs);
   }
 
-  private void buildTrackGroups(MediaPresentationDescription manifest) {
-    Period period = manifest.getPeriod(0);
-    int trackGroupCount = 0;
-    trackGroupAdaptationSetIndices = new int[period.adaptationSets.size()];
-    TrackGroup[] trackGroupArray = new TrackGroup[period.adaptationSets.size()];
-    for (int i = 0; i < period.adaptationSets.size(); i++) {
-      AdaptationSet adaptationSet = period.adaptationSets.get(i);
-      int adaptationSetType = adaptationSet.type;
-      List<Representation> representations = adaptationSet.representations;
-      if (!representations.isEmpty() && (adaptationSetType == C.TRACK_TYPE_AUDIO
-          || adaptationSetType == C.TRACK_TYPE_VIDEO || adaptationSetType == C.TRACK_TYPE_TEXT)) {
-        Format[] formats = new Format[representations.size()];
-        for (int j = 0; j < formats.length; j++) {
-          formats[j] = representations.get(j).format;
-        }
-        trackGroupAdaptationSetIndices[trackGroupCount] = i;
-        boolean adaptive = adaptationSetType == C.TRACK_TYPE_VIDEO;
-        trackGroupArray[trackGroupCount++] = new TrackGroup(adaptive, formats);
-      }
-    }
-    if (trackGroupCount < trackGroupArray.length) {
-      trackGroupAdaptationSetIndices = Arrays.copyOf(trackGroupAdaptationSetIndices,
-          trackGroupCount);
-      trackGroupArray = Arrays.copyOf(trackGroupArray, trackGroupCount);
-    }
-    trackGroups = new TrackGroupArray(trackGroupArray);
-  }
-
-  private ChunkSampleStream<DashChunkSource> buildSampleStream(TrackSelection selection,
-      long positionUs) {
-    int[] selectedTracks = selection.getTracks();
-    FormatEvaluator adaptiveEvaluator = selectedTracks.length > 1
-        ? new AdaptiveEvaluator(bandwidthMeter) : null;
-    int adaptationSetIndex = trackGroupAdaptationSetIndices[selection.group];
-    AdaptationSet adaptationSet = manifest.getPeriod(0).adaptationSets.get(
-        adaptationSetIndex);
-    int adaptationSetType = adaptationSet.type;
-    DataSource dataSource = dataSourceFactory.createDataSource(bandwidthMeter);
-    DashChunkSource chunkSource = new DashChunkSource(loader, manifest, adaptationSetIndex,
-        trackGroups.get(selection.group), selectedTracks, dataSource, adaptiveEvaluator,
-        elapsedRealtimeOffset);
-    return new ChunkSampleStream<>(adaptationSetType, chunkSource, this, allocator, positionUs,
-        minLoadableRetryCount, eventDispatcher);
-  }
-
-  @SuppressWarnings("unchecked")
-  private static ChunkSampleStream<DashChunkSource>[] newSampleStreamArray(int length) {
-    return new ChunkSampleStream[length];
-  }
-
   private final class ManifestCallback implements
       Loader.Callback<ParsingLoadable<MediaPresentationDescription>> {