1 files changed, 791 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java
new file mode 100644
index 0000000000..a789805cd7
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/chunk/ChunkSampleStream.java
@@ -0,0 +1,791 @@
+/*
+ * 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 org.mozilla.thirdparty.com.google.android.exoplayer2.source.chunk;
+
+import androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.FormatHolder;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.SeekParameters;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.decoder.DecoderInputBuffer;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.drm.DrmSession;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.drm.DrmSessionManager;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.SampleQueue;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.SampleStream;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.SequenceableLoader;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.Allocator;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.LoadErrorHandlingPolicy;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.Loader;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.Loader.LoadErrorAction;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Log;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A {@link SampleStream} that loads media in {@link Chunk}s, obtained from a {@link ChunkSource}.
+ * May also be configured to expose additional embedded {@link SampleStream}s.
+ */
+public class ChunkSampleStream<T extends ChunkSource> implements SampleStream, SequenceableLoader,
+    Loader.Callback<Chunk>, Loader.ReleaseCallback {
+
+  /** A callback to be notified when a sample stream has finished being released. */
+  public interface ReleaseCallback<T extends ChunkSource> {
+
+    /**
+     * Called when the {@link ChunkSampleStream} has finished being released.
+     *
+     * @param chunkSampleStream The released sample stream.
+     */
+    void onSampleStreamReleased(ChunkSampleStream<T> chunkSampleStream);
+  }
+
+  private static final String TAG = "ChunkSampleStream";
+
+  public final int primaryTrackType;
+
+  @Nullable private final int[] embeddedTrackTypes;
+  @Nullable private final Format[] embeddedTrackFormats;
+  private final boolean[] embeddedTracksSelected;
+  private final T chunkSource;
+  private final SequenceableLoader.Callback<ChunkSampleStream<T>> callback;
+  private final EventDispatcher eventDispatcher;
+  private final LoadErrorHandlingPolicy loadErrorHandlingPolicy;
+  private final Loader loader;
+  private final ChunkHolder nextChunkHolder;
+  private final ArrayList<BaseMediaChunk> mediaChunks;
+  private final List<BaseMediaChunk> readOnlyMediaChunks;
+  private final SampleQueue primarySampleQueue;
+  private final SampleQueue[] embeddedSampleQueues;
+  private final BaseMediaChunkOutput chunkOutput;
+
+  private Format primaryDownstreamTrackFormat;
+  @Nullable private ReleaseCallback<T> releaseCallback;
+  private long pendingResetPositionUs;
+  private long lastSeekPositionUs;
+  private int nextNotifyPrimaryFormatMediaChunkIndex;
+
+  /* package */ long decodeOnlyUntilPositionUs;
+  /* package */ boolean loadingFinished;
+
+  /**
+   * Constructs an instance.
+   *
+   * @param primaryTrackType The type of the primary track. One of the {@link C} {@code
+   *     TRACK_TYPE_*} constants.
+   * @param embeddedTrackTypes The types of any embedded tracks, or null.
+   * @param embeddedTrackFormats The formats of the embedded tracks, or null.
+   * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
+   * @param callback An {@link Callback} for the stream.
+   * @param allocator An {@link Allocator} from which allocations can be obtained.
+   * @param positionUs The position from which to start loading media.
+   * @param drmSessionManager The {@link DrmSessionManager} to obtain {@link DrmSession DrmSessions}
+   *     from.
+   * @param loadErrorHandlingPolicy The {@link LoadErrorHandlingPolicy}.
+   * @param eventDispatcher A dispatcher to notify of events.
+   */
+  public ChunkSampleStream(
+      int primaryTrackType,
+      @Nullable int[] embeddedTrackTypes,
+      @Nullable Format[] embeddedTrackFormats,
+      T chunkSource,
+      Callback<ChunkSampleStream<T>> callback,
+      Allocator allocator,
+      long positionUs,
+      DrmSessionManager<?> drmSessionManager,
+      LoadErrorHandlingPolicy loadErrorHandlingPolicy,
+      EventDispatcher eventDispatcher) {
+    this.primaryTrackType = primaryTrackType;
+    this.embeddedTrackTypes = embeddedTrackTypes;
+    this.embeddedTrackFormats = embeddedTrackFormats;
+    this.chunkSource = chunkSource;
+    this.callback = callback;
+    this.eventDispatcher = eventDispatcher;
+    this.loadErrorHandlingPolicy = loadErrorHandlingPolicy;
+    loader = new Loader("Loader:ChunkSampleStream");
+    nextChunkHolder = new ChunkHolder();
+    mediaChunks = new ArrayList<>();
+    readOnlyMediaChunks = Collections.unmodifiableList(mediaChunks);
+
+    int embeddedTrackCount = embeddedTrackTypes == null ? 0 : embeddedTrackTypes.length;
+    embeddedSampleQueues = new SampleQueue[embeddedTrackCount];
+    embeddedTracksSelected = new boolean[embeddedTrackCount];
+    int[] trackTypes = new int[1 + embeddedTrackCount];
+    SampleQueue[] sampleQueues = new SampleQueue[1 + embeddedTrackCount];
+
+    primarySampleQueue = new SampleQueue(allocator, drmSessionManager);
+    trackTypes[0] = primaryTrackType;
+    sampleQueues[0] = primarySampleQueue;
+
+    for (int i = 0; i < embeddedTrackCount; i++) {
+      SampleQueue sampleQueue =
+          new SampleQueue(allocator, DrmSessionManager.getDummyDrmSessionManager());
+      embeddedSampleQueues[i] = sampleQueue;
+      sampleQueues[i + 1] = sampleQueue;
+      trackTypes[i + 1] = embeddedTrackTypes[i];
+    }
+
+    chunkOutput = new BaseMediaChunkOutput(trackTypes, sampleQueues);
+    pendingResetPositionUs = positionUs;
+    lastSeekPositionUs = positionUs;
+  }
+
+  /**
+   * Discards buffered media up to the specified position.
+   *
+   * @param positionUs The position to discard up to, in microseconds.
+   * @param toKeyframe If true then for each track discards samples up to the keyframe before or at
+   *     the specified position, rather than any sample before or at that position.
+   */
+  public void discardBuffer(long positionUs, boolean toKeyframe) {
+    if (isPendingReset()) {
+      return;
+    }
+    int oldFirstSampleIndex = primarySampleQueue.getFirstIndex();
+    primarySampleQueue.discardTo(positionUs, toKeyframe, true);
+    int newFirstSampleIndex = primarySampleQueue.getFirstIndex();
+    if (newFirstSampleIndex > oldFirstSampleIndex) {
+      long discardToUs = primarySampleQueue.getFirstTimestampUs();
+      for (int i = 0; i < embeddedSampleQueues.length; i++) {
+        embeddedSampleQueues[i].discardTo(discardToUs, toKeyframe, embeddedTracksSelected[i]);
+      }
+    }
+    discardDownstreamMediaChunks(newFirstSampleIndex);
+  }
+
+  /**
+   * Selects the embedded track, returning a new {@link EmbeddedSampleStream} from which the track's
+   * samples can be consumed. {@link EmbeddedSampleStream#release()} must be called on the returned
+   * stream when the track is no longer required, and before calling this method again to obtain
+   * another stream for the same track.
+   *
+   * @param positionUs The current playback position in microseconds.
+   * @param trackType The type of the embedded track to enable.
+   * @return The {@link EmbeddedSampleStream} for the embedded track.
+   */
+  public EmbeddedSampleStream selectEmbeddedTrack(long positionUs, int trackType) {
+    for (int i = 0; i < embeddedSampleQueues.length; i++) {
+      if (embeddedTrackTypes[i] == trackType) {
+        Assertions.checkState(!embeddedTracksSelected[i]);
+        embeddedTracksSelected[i] = true;
+        embeddedSampleQueues[i].seekTo(positionUs, /* allowTimeBeyondBuffer= */ true);
+        return new EmbeddedSampleStream(this, embeddedSampleQueues[i], i);
+      }
+    }
+    // Should never happen.
+    throw new IllegalStateException();
+  }
+
+  /**
+   * Returns the {@link ChunkSource} used by this stream.
+   */
+  public T getChunkSource() {
+    return chunkSource;
+  }
+
+  /**
+   * Returns an estimate of the position up to which data is buffered.
+   *
+   * @return An estimate of the absolute position in microseconds up to which data is buffered, or
+   *     {@link C#TIME_END_OF_SOURCE} if the track is fully buffered.
+   */
+  @Override
+  public long getBufferedPositionUs() {
+    if (loadingFinished) {
+      return C.TIME_END_OF_SOURCE;
+    } else if (isPendingReset()) {
+      return pendingResetPositionUs;
+    } else {
+      long bufferedPositionUs = lastSeekPositionUs;
+      BaseMediaChunk lastMediaChunk = getLastMediaChunk();
+      BaseMediaChunk lastCompletedMediaChunk = lastMediaChunk.isLoadCompleted() ? lastMediaChunk
+          : mediaChunks.size() > 1 ? mediaChunks.get(mediaChunks.size() - 2) : null;
+      if (lastCompletedMediaChunk != null) {
+        bufferedPositionUs = Math.max(bufferedPositionUs, lastCompletedMediaChunk.endTimeUs);
+      }
+      return Math.max(bufferedPositionUs, primarySampleQueue.getLargestQueuedTimestampUs());
+    }
+  }
+
+  /**
+   * Adjusts a seek position given the specified {@link SeekParameters}. Chunk boundaries are used
+   * as sync points.
+   *
+   * @param positionUs The seek position in microseconds.
+   * @param seekParameters Parameters that control how the seek is performed.
+   * @return The adjusted seek position, in microseconds.
+   */
+  public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
+    return chunkSource.getAdjustedSeekPositionUs(positionUs, seekParameters);
+  }
+
+  /**
+   * Seeks to the specified position in microseconds.
+   *
+   * @param positionUs The seek position in microseconds.
+   */
+  public void seekToUs(long positionUs) {
+    lastSeekPositionUs = positionUs;
+    if (isPendingReset()) {
+      // A reset is already pending. We only need to update its position.
+      pendingResetPositionUs = positionUs;
+      return;
+    }
+
+    // Detect whether the seek is to the start of a chunk that's at least partially buffered.
+    BaseMediaChunk seekToMediaChunk = null;
+    for (int i = 0; i < mediaChunks.size(); i++) {
+      BaseMediaChunk mediaChunk = mediaChunks.get(i);
+      long mediaChunkStartTimeUs = mediaChunk.startTimeUs;
+      if (mediaChunkStartTimeUs == positionUs && mediaChunk.clippedStartTimeUs == C.TIME_UNSET) {
+        seekToMediaChunk = mediaChunk;
+        break;
+      } else if (mediaChunkStartTimeUs > positionUs) {
+        // We're not going to find a chunk with a matching start time.
+        break;
+      }
+    }
+
+    // See if we can seek inside the primary sample queue.
+    boolean seekInsideBuffer;
+    if (seekToMediaChunk != null) {
+      // When seeking to the start of a chunk we use the index of the first sample in the chunk
+      // rather than the seek position. This ensures we seek to the keyframe at the start of the
+      // chunk even if the sample timestamps are slightly offset from the chunk start times.
+      seekInsideBuffer = primarySampleQueue.seekTo(seekToMediaChunk.getFirstSampleIndex(0));
+      decodeOnlyUntilPositionUs = 0;
+    } else {
+      seekInsideBuffer =
+          primarySampleQueue.seekTo(
+              positionUs, /* allowTimeBeyondBuffer= */ positionUs < getNextLoadPositionUs());
+      decodeOnlyUntilPositionUs = lastSeekPositionUs;
+    }
+
+    if (seekInsideBuffer) {
+      // We can seek inside the buffer.
+      nextNotifyPrimaryFormatMediaChunkIndex =
+          primarySampleIndexToMediaChunkIndex(
+              primarySampleQueue.getReadIndex(), /* minChunkIndex= */ 0);
+      // Seek the embedded sample queues.
+      for (SampleQueue embeddedSampleQueue : embeddedSampleQueues) {
+        embeddedSampleQueue.seekTo(positionUs, /* allowTimeBeyondBuffer= */ true);
+      }
+    } else {
+      // We can't seek inside the buffer, and so need to reset.
+      pendingResetPositionUs = positionUs;
+      loadingFinished = false;
+      mediaChunks.clear();
+      nextNotifyPrimaryFormatMediaChunkIndex = 0;
+      if (loader.isLoading()) {
+        loader.cancelLoading();
+      } else {
+        loader.clearFatalError();
+        primarySampleQueue.reset();
+        for (SampleQueue embeddedSampleQueue : embeddedSampleQueues) {
+          embeddedSampleQueue.reset();
+        }
+      }
+    }
+  }
+
+  /**
+   * Releases the stream.
+   *
+   * <p>This method should be called when the stream is no longer required. Either this method or
+   * {@link #release(ReleaseCallback)} can be used to release this stream.
+   */
+  public void release() {
+    release(null);
+  }
+
+  /**
+   * Releases the stream.
+   *
+   * <p>This method should be called when the stream is no longer required. Either this method or
+   * {@link #release()} can be used to release this stream.
+   *
+   * @param callback An optional callback to be called on the loading thread once the loader has
+   *     been released.
+   */
+  public void release(@Nullable ReleaseCallback<T> callback) {
+    this.releaseCallback = callback;
+    // Discard as much as we can synchronously.
+    primarySampleQueue.preRelease();
+    for (SampleQueue embeddedSampleQueue : embeddedSampleQueues) {
+      embeddedSampleQueue.preRelease();
+    }
+    loader.release(this);
+  }
+
+  @Override
+  public void onLoaderReleased() {
+    primarySampleQueue.release();
+    for (SampleQueue embeddedSampleQueue : embeddedSampleQueues) {
+      embeddedSampleQueue.release();
+    }
+    if (releaseCallback != null) {
+      releaseCallback.onSampleStreamReleased(this);
+    }
+  }
+
+  // SampleStream implementation.
+
+  @Override
+  public boolean isReady() {
+    return !isPendingReset() && primarySampleQueue.isReady(loadingFinished);
+  }
+
+  @Override
+  public void maybeThrowError() throws IOException {
+    loader.maybeThrowError();
+    primarySampleQueue.maybeThrowError();
+    if (!loader.isLoading()) {
+      chunkSource.maybeThrowError();
+    }
+  }
+
+  @Override
+  public int readData(FormatHolder formatHolder, DecoderInputBuffer buffer,
+      boolean formatRequired) {
+    if (isPendingReset()) {
+      return C.RESULT_NOTHING_READ;
+    }
+    maybeNotifyPrimaryTrackFormatChanged();
+
+    return primarySampleQueue.read(
+        formatHolder, buffer, formatRequired, loadingFinished, decodeOnlyUntilPositionUs);
+  }
+
+  @Override
+  public int skipData(long positionUs) {
+    if (isPendingReset()) {
+      return 0;
+    }
+    int skipCount;
+    if (loadingFinished && positionUs > primarySampleQueue.getLargestQueuedTimestampUs()) {
+      skipCount = primarySampleQueue.advanceToEnd();
+    } else {
+      skipCount = primarySampleQueue.advanceTo(positionUs);
+    }
+    maybeNotifyPrimaryTrackFormatChanged();
+    return skipCount;
+  }
+
+  // Loader.Callback implementation.
+
+  @Override
+  public void onLoadCompleted(Chunk loadable, long elapsedRealtimeMs, long loadDurationMs) {
+    chunkSource.onChunkLoadCompleted(loadable);
+    eventDispatcher.loadCompleted(
+        loadable.dataSpec,
+        loadable.getUri(),
+        loadable.getResponseHeaders(),
+        loadable.type,
+        primaryTrackType,
+        loadable.trackFormat,
+        loadable.trackSelectionReason,
+        loadable.trackSelectionData,
+        loadable.startTimeUs,
+        loadable.endTimeUs,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        loadable.bytesLoaded());
+    callback.onContinueLoadingRequested(this);
+  }
+
+  @Override
+  public void onLoadCanceled(Chunk loadable, long elapsedRealtimeMs, long loadDurationMs,
+      boolean released) {
+    eventDispatcher.loadCanceled(
+        loadable.dataSpec,
+        loadable.getUri(),
+        loadable.getResponseHeaders(),
+        loadable.type,
+        primaryTrackType,
+        loadable.trackFormat,
+        loadable.trackSelectionReason,
+        loadable.trackSelectionData,
+        loadable.startTimeUs,
+        loadable.endTimeUs,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        loadable.bytesLoaded());
+    if (!released) {
+      primarySampleQueue.reset();
+      for (SampleQueue embeddedSampleQueue : embeddedSampleQueues) {
+        embeddedSampleQueue.reset();
+      }
+      callback.onContinueLoadingRequested(this);
+    }
+  }
+
+  @Override
+  public LoadErrorAction onLoadError(
+      Chunk loadable,
+      long elapsedRealtimeMs,
+      long loadDurationMs,
+      IOException error,
+      int errorCount) {
+    long bytesLoaded = loadable.bytesLoaded();
+    boolean isMediaChunk = isMediaChunk(loadable);
+    int lastChunkIndex = mediaChunks.size() - 1;
+    boolean cancelable =
+        bytesLoaded == 0 || !isMediaChunk || !haveReadFromMediaChunk(lastChunkIndex);
+    long blacklistDurationMs =
+        cancelable
+            ? loadErrorHandlingPolicy.getBlacklistDurationMsFor(
+                loadable.type, loadDurationMs, error, errorCount)
+            : C.TIME_UNSET;
+    LoadErrorAction loadErrorAction = null;
+    if (chunkSource.onChunkLoadError(loadable, cancelable, error, blacklistDurationMs)) {
+      if (cancelable) {
+        loadErrorAction = Loader.DONT_RETRY;
+        if (isMediaChunk) {
+          BaseMediaChunk removed = discardUpstreamMediaChunksFromIndex(lastChunkIndex);
+          Assertions.checkState(removed == loadable);
+          if (mediaChunks.isEmpty()) {
+            pendingResetPositionUs = lastSeekPositionUs;
+          }
+        }
+      } else {
+        Log.w(TAG, "Ignoring attempt to cancel non-cancelable load.");
+      }
+    }
+
+    if (loadErrorAction == null) {
+      // The load was not cancelled. Either the load must be retried or the error propagated.
+      long retryDelayMs =
+          loadErrorHandlingPolicy.getRetryDelayMsFor(
+              loadable.type, loadDurationMs, error, errorCount);
+      loadErrorAction =
+          retryDelayMs != C.TIME_UNSET
+              ? Loader.createRetryAction(/* resetErrorCount= */ false, retryDelayMs)
+              : Loader.DONT_RETRY_FATAL;
+    }
+
+    boolean canceled = !loadErrorAction.isRetry();
+    eventDispatcher.loadError(
+        loadable.dataSpec,
+        loadable.getUri(),
+        loadable.getResponseHeaders(),
+        loadable.type,
+        primaryTrackType,
+        loadable.trackFormat,
+        loadable.trackSelectionReason,
+        loadable.trackSelectionData,
+        loadable.startTimeUs,
+        loadable.endTimeUs,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        bytesLoaded,
+        error,
+        canceled);
+    if (canceled) {
+      callback.onContinueLoadingRequested(this);
+    }
+    return loadErrorAction;
+  }
+
+  // SequenceableLoader implementation
+
+  @Override
+  public boolean continueLoading(long positionUs) {
+    if (loadingFinished || loader.isLoading() || loader.hasFatalError()) {
+      return false;
+    }
+
+    boolean pendingReset = isPendingReset();
+    List<BaseMediaChunk> chunkQueue;
+    long loadPositionUs;
+    if (pendingReset) {
+      chunkQueue = Collections.emptyList();
+      loadPositionUs = pendingResetPositionUs;
+    } else {
+      chunkQueue = readOnlyMediaChunks;
+      loadPositionUs = getLastMediaChunk().endTimeUs;
+    }
+    chunkSource.getNextChunk(positionUs, loadPositionUs, chunkQueue, nextChunkHolder);
+    boolean endOfStream = nextChunkHolder.endOfStream;
+    Chunk loadable = nextChunkHolder.chunk;
+    nextChunkHolder.clear();
+
+    if (endOfStream) {
+      pendingResetPositionUs = C.TIME_UNSET;
+      loadingFinished = true;
+      return true;
+    }
+
+    if (loadable == null) {
+      return false;
+    }
+
+    if (isMediaChunk(loadable)) {
+      BaseMediaChunk mediaChunk = (BaseMediaChunk) loadable;
+      if (pendingReset) {
+        boolean resetToMediaChunk = mediaChunk.startTimeUs == pendingResetPositionUs;
+        // Only enable setting of the decode only flag if we're not resetting to a chunk boundary.
+        decodeOnlyUntilPositionUs = resetToMediaChunk ? 0 : pendingResetPositionUs;
+        pendingResetPositionUs = C.TIME_UNSET;
+      }
+      mediaChunk.init(chunkOutput);
+      mediaChunks.add(mediaChunk);
+    } else if (loadable instanceof InitializationChunk) {
+      ((InitializationChunk) loadable).init(chunkOutput);
+    }
+    long elapsedRealtimeMs =
+        loader.startLoading(
+            loadable, this, loadErrorHandlingPolicy.getMinimumLoadableRetryCount(loadable.type));
+    eventDispatcher.loadStarted(
+        loadable.dataSpec,
+        loadable.type,
+        primaryTrackType,
+        loadable.trackFormat,
+        loadable.trackSelectionReason,
+        loadable.trackSelectionData,
+        loadable.startTimeUs,
+        loadable.endTimeUs,
+        elapsedRealtimeMs);
+    return true;
+  }
+
+  @Override
+  public boolean isLoading() {
+    return loader.isLoading();
+  }
+
+  @Override
+  public long getNextLoadPositionUs() {
+    if (isPendingReset()) {
+      return pendingResetPositionUs;
+    } else {
+      return loadingFinished ? C.TIME_END_OF_SOURCE : getLastMediaChunk().endTimeUs;
+    }
+  }
+
+  @Override
+  public void reevaluateBuffer(long positionUs) {
+    if (loader.isLoading() || loader.hasFatalError() || isPendingReset()) {
+      return;
+    }
+
+    int currentQueueSize = mediaChunks.size();
+    int preferredQueueSize = chunkSource.getPreferredQueueSize(positionUs, readOnlyMediaChunks);
+    if (currentQueueSize <= preferredQueueSize) {
+      return;
+    }
+
+    int newQueueSize = currentQueueSize;
+    for (int i = preferredQueueSize; i < currentQueueSize; i++) {
+      if (!haveReadFromMediaChunk(i)) {
+        newQueueSize = i;
+        break;
+      }
+    }
+    if (newQueueSize == currentQueueSize) {
+      return;
+    }
+
+    long endTimeUs = getLastMediaChunk().endTimeUs;
+    BaseMediaChunk firstRemovedChunk = discardUpstreamMediaChunksFromIndex(newQueueSize);
+    if (mediaChunks.isEmpty()) {
+      pendingResetPositionUs = lastSeekPositionUs;
+    }
+    loadingFinished = false;
+    eventDispatcher.upstreamDiscarded(primaryTrackType, firstRemovedChunk.startTimeUs, endTimeUs);
+  }
+
+  // Internal methods
+
+  private boolean isMediaChunk(Chunk chunk) {
+    return chunk instanceof BaseMediaChunk;
+  }
+
+  /** Returns whether samples have been read from media chunk at given index. */
+  private boolean haveReadFromMediaChunk(int mediaChunkIndex) {
+    BaseMediaChunk mediaChunk = mediaChunks.get(mediaChunkIndex);
+    if (primarySampleQueue.getReadIndex() > mediaChunk.getFirstSampleIndex(0)) {
+      return true;
+    }
+    for (int i = 0; i < embeddedSampleQueues.length; i++) {
+      if (embeddedSampleQueues[i].getReadIndex() > mediaChunk.getFirstSampleIndex(i + 1)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /* package */ boolean isPendingReset() {
+    return pendingResetPositionUs != C.TIME_UNSET;
+  }
+
+  private void discardDownstreamMediaChunks(int discardToSampleIndex) {
+    int discardToMediaChunkIndex =
+        primarySampleIndexToMediaChunkIndex(discardToSampleIndex, /* minChunkIndex= */ 0);
+    // Don't discard any chunks that we haven't reported the primary format change for yet.
+    discardToMediaChunkIndex =
+        Math.min(discardToMediaChunkIndex, nextNotifyPrimaryFormatMediaChunkIndex);
+    if (discardToMediaChunkIndex > 0) {
+      Util.removeRange(mediaChunks, /* fromIndex= */ 0, /* toIndex= */ discardToMediaChunkIndex);
+      nextNotifyPrimaryFormatMediaChunkIndex -= discardToMediaChunkIndex;
+    }
+  }
+
+  private void maybeNotifyPrimaryTrackFormatChanged() {
+    int readSampleIndex = primarySampleQueue.getReadIndex();
+    int notifyToMediaChunkIndex =
+        primarySampleIndexToMediaChunkIndex(
+            readSampleIndex, /* minChunkIndex= */ nextNotifyPrimaryFormatMediaChunkIndex - 1);
+    while (nextNotifyPrimaryFormatMediaChunkIndex <= notifyToMediaChunkIndex) {
+      maybeNotifyPrimaryTrackFormatChanged(nextNotifyPrimaryFormatMediaChunkIndex++);
+    }
+  }
+
+  private void maybeNotifyPrimaryTrackFormatChanged(int mediaChunkReadIndex) {
+    BaseMediaChunk currentChunk = mediaChunks.get(mediaChunkReadIndex);
+    Format trackFormat = currentChunk.trackFormat;
+    if (!trackFormat.equals(primaryDownstreamTrackFormat)) {
+      eventDispatcher.downstreamFormatChanged(primaryTrackType, trackFormat,
+          currentChunk.trackSelectionReason, currentChunk.trackSelectionData,
+          currentChunk.startTimeUs);
+    }
+    primaryDownstreamTrackFormat = trackFormat;
+  }
+
+  /**
+   * Returns the media chunk index corresponding to a given primary sample index.
+   *
+   * @param primarySampleIndex The primary sample index for which the corresponding media chunk
+   *     index is required.
+   * @param minChunkIndex A minimum chunk index from which to start searching, or -1 if no hint can
+   *     be provided.
+   * @return The index of the media chunk corresponding to the sample index, or -1 if the list of
+   *     media chunks is empty, or {@code minChunkIndex} if the sample precedes the first chunk in
+   *     the search (i.e. the chunk at {@code minChunkIndex}, or at index 0 if {@code minChunkIndex}
+   *     is -1.
+   */
+  private int primarySampleIndexToMediaChunkIndex(int primarySampleIndex, int minChunkIndex) {
+    for (int i = minChunkIndex + 1; i < mediaChunks.size(); i++) {
+      if (mediaChunks.get(i).getFirstSampleIndex(0) > primarySampleIndex) {
+        return i - 1;
+      }
+    }
+    return mediaChunks.size() - 1;
+  }
+
+  private BaseMediaChunk getLastMediaChunk() {
+    return mediaChunks.get(mediaChunks.size() - 1);
+  }
+
+  /**
+   * Discard upstream media chunks from {@code chunkIndex} and corresponding samples from sample
+   * queues.
+   *
+   * @param chunkIndex The index of the first chunk to discard.
+   * @return The chunk at given index.
+   */
+  private BaseMediaChunk discardUpstreamMediaChunksFromIndex(int chunkIndex) {
+    BaseMediaChunk firstRemovedChunk = mediaChunks.get(chunkIndex);
+    Util.removeRange(mediaChunks, /* fromIndex= */ chunkIndex, /* toIndex= */ mediaChunks.size());
+    nextNotifyPrimaryFormatMediaChunkIndex =
+        Math.max(nextNotifyPrimaryFormatMediaChunkIndex, mediaChunks.size());
+    primarySampleQueue.discardUpstreamSamples(firstRemovedChunk.getFirstSampleIndex(0));
+    for (int i = 0; i < embeddedSampleQueues.length; i++) {
+      embeddedSampleQueues[i].discardUpstreamSamples(firstRemovedChunk.getFirstSampleIndex(i + 1));
+    }
+    return firstRemovedChunk;
+  }
+
+  /**
+   * A {@link SampleStream} embedded in a {@link ChunkSampleStream}.
+   */
+  public final class EmbeddedSampleStream implements SampleStream {
+
+    public final ChunkSampleStream<T> parent;
+
+    private final SampleQueue sampleQueue;
+    private final int index;
+
+    private boolean notifiedDownstreamFormat;
+
+    public EmbeddedSampleStream(ChunkSampleStream<T> parent, SampleQueue sampleQueue, int index) {
+      this.parent = parent;
+      this.sampleQueue = sampleQueue;
+      this.index = index;
+    }
+
+    @Override
+    public boolean isReady() {
+      return !isPendingReset() && sampleQueue.isReady(loadingFinished);
+    }
+
+    @Override
+    public int skipData(long positionUs) {
+      if (isPendingReset()) {
+        return 0;
+      }
+      maybeNotifyDownstreamFormat();
+      int skipCount;
+      if (loadingFinished && positionUs > sampleQueue.getLargestQueuedTimestampUs()) {
+        skipCount = sampleQueue.advanceToEnd();
+      } else {
+        skipCount = sampleQueue.advanceTo(positionUs);
+      }
+      return skipCount;
+    }
+
+    @Override
+    public void maybeThrowError() throws IOException {
+      // Do nothing. Errors will be thrown from the primary stream.
+    }
+
+    @Override
+    public int readData(FormatHolder formatHolder, DecoderInputBuffer buffer,
+        boolean formatRequired) {
+      if (isPendingReset()) {
+        return C.RESULT_NOTHING_READ;
+      }
+      maybeNotifyDownstreamFormat();
+      return sampleQueue.read(
+          formatHolder,
+          buffer,
+          formatRequired,
+          loadingFinished,
+          decodeOnlyUntilPositionUs);
+    }
+
+    public void release() {
+      Assertions.checkState(embeddedTracksSelected[index]);
+      embeddedTracksSelected[index] = false;
+    }
+
+    private void maybeNotifyDownstreamFormat() {
+      if (!notifiedDownstreamFormat) {
+        eventDispatcher.downstreamFormatChanged(
+            embeddedTrackTypes[index],
+            embeddedTrackFormats[index],
+            C.SELECTION_REASON_UNKNOWN,
+            /* trackSelectionData= */ null,
+            lastSeekPositionUs);
+        notifiedDownstreamFormat = true;
+      }
+    }
+  }
+
+}