Allow late HLS sample queue building

Issue:#3149

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=177836048

ISSUE_TEMPLATE

+*** ISSUES THAT IGNORE THIS TEMPLATE WILL BE CLOSED WITHOUT INVESTIGATION ***
+
 Before filing an issue:
 -----------------------
 - Search existing issues, including issues that are closed.

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStream.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source.hls;
 
+import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.FormatHolder;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.source.SampleStream;
@@ -25,33 +26,60 @@ import java.io.IOException;
  */
 /* package */ final class HlsSampleStream implements SampleStream {
 
-  public final int sampleQueueIndex;
-
+  private final int trackGroupIndex;
   private final HlsSampleStreamWrapper sampleStreamWrapper;
+  private int sampleQueueIndex;
 
-  public HlsSampleStream(HlsSampleStreamWrapper sampleStreamWrapper, int sampleQueueIndex) {
+  public HlsSampleStream(HlsSampleStreamWrapper sampleStreamWrapper, int trackGroupIndex) {
     this.sampleStreamWrapper = sampleStreamWrapper;
-    this.sampleQueueIndex = sampleQueueIndex;
+    this.trackGroupIndex = trackGroupIndex;
+  }
+
+  public void unbindSampleQueue() {
+    if (sampleQueueIndex != C.INDEX_UNSET) {
+      sampleStreamWrapper.unbindSampleQueue(trackGroupIndex);
+    }
   }
 
+  // SampleStream implementation.
+
   @Override
   public boolean isReady() {
-    return sampleStreamWrapper.isReady(sampleQueueIndex);
+    return ensureBoundSampleQueue() && sampleStreamWrapper.isReady(sampleQueueIndex);
   }
 
   @Override
   public void maybeThrowError() throws IOException {
+    if (!ensureBoundSampleQueue()) {
+      throw new SampleQueueMappingException(
+          sampleStreamWrapper.getTrackGroups().get(trackGroupIndex).getFormat(0).sampleMimeType);
+    }
     sampleStreamWrapper.maybeThrowError();
   }
 
   @Override
   public int readData(FormatHolder formatHolder, DecoderInputBuffer buffer, boolean requireFormat) {
+    if (!ensureBoundSampleQueue()) {
+      return C.RESULT_NOTHING_READ;
+    }
     return sampleStreamWrapper.readData(sampleQueueIndex, formatHolder, buffer, requireFormat);
   }
 
   @Override
   public int skipData(long positionUs) {
+    if (!ensureBoundSampleQueue()) {
+      return 0;
+    }
     return sampleStreamWrapper.skipData(sampleQueueIndex, positionUs);
   }
 
+  // Internal methods.
+
+  private boolean ensureBoundSampleQueue() {
+    if (sampleQueueIndex != C.INDEX_UNSET) {
+      return true;
+    }
+    sampleQueueIndex = sampleStreamWrapper.bindSampleQueueToSampleStream(trackGroupIndex);
+    return sampleQueueIndex != C.INDEX_UNSET;
+  }
 }

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java

@@ -88,13 +88,14 @@ import java.util.Arrays;
   private final HlsChunkSource.HlsChunkHolder nextChunkHolder;
   private final ArrayList<HlsMediaChunk> mediaChunks;
   private final Runnable maybeFinishPrepareRunnable;
+  private final Runnable onTracksEndedRunnable;
   private final Handler handler;
 
   private SampleQueue[] sampleQueues;
   private int[] sampleQueueTrackIds;
   private boolean sampleQueuesBuilt;
   private boolean prepared;
-  private int enabledSampleQueueCount;
+  private int enabledTrackGroupCount;
   private Format downstreamTrackFormat;
   private boolean released;
 
@@ -108,13 +109,16 @@ import java.util.Arrays;
   private boolean[] sampleQueuesEnabledStates;
   private boolean[] sampleQueueIsAudioVideoFlags;
 
-  private long sampleOffsetUs;
   private long lastSeekPositionUs;
   private long pendingResetPositionUs;
   private boolean pendingResetUpstreamFormats;
   private boolean seenFirstTrackSelection;
   private boolean loadingFinished;
 
+  // Accessed only by the loading thread.
+  private boolean tracksEnded;
+  private long sampleOffsetUs;
+
   /**
    * @param trackType The type of the track. One of the {@link C} {@code TRACK_TYPE_*} constants.
    * @param callback A callback for the wrapper.
@@ -143,12 +147,20 @@ import java.util.Arrays;
     sampleQueueIsAudioVideoFlags = new boolean[0];
     sampleQueuesEnabledStates = new boolean[0];
     mediaChunks = new ArrayList<>();
-    maybeFinishPrepareRunnable = new Runnable() {
-      @Override
-      public void run() {
-        maybeFinishPrepare();
-      }
-    };
+    maybeFinishPrepareRunnable =
+        new Runnable() {
+          @Override
+          public void run() {
+            maybeFinishPrepare();
+          }
+        };
+    onTracksEndedRunnable =
+        new Runnable() {
+          @Override
+          public void run() {
+            onTracksEnded();
+          }
+        };
     handler = new Handler();
     lastSeekPositionUs = positionUs;
     pendingResetPositionUs = positionUs;
@@ -166,8 +178,8 @@ import java.util.Arrays;
    */
   public void prepareSingleTrack(Format format) {
     track(0, C.TRACK_TYPE_UNKNOWN).format(format);
-    sampleQueuesBuilt = true;
-    maybeFinishPrepare();
+    tracksEnded = true;
+    onTracksEnded();
   }
 
   public void maybeThrowPrepareError() throws IOException {
@@ -178,6 +190,19 @@ import java.util.Arrays;
     return trackGroups;
   }
 
+  public int bindSampleQueueToSampleStream(int trackGroupIndex) {
+    int sampleQueueIndex = trackGroupToSampleQueueIndex[trackGroupIndex];
+    if (sampleQueueIndex == C.INDEX_UNSET) {
+      return C.INDEX_UNSET;
+    }
+    setSampleQueueEnabledState(sampleQueueIndex, true);
+    return sampleQueueIndex;
+  }
+
+  public void unbindSampleQueue(int trackGroupIndex) {
+    setSampleQueueEnabledState(trackGroupToSampleQueueIndex[trackGroupIndex], false);
+  }
+
   /**
    * Called by the parent {@link HlsMediaPeriod} when a track selection occurs.
    *
@@ -198,20 +223,23 @@ import java.util.Arrays;
   public boolean selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
       SampleStream[] streams, boolean[] streamResetFlags, long positionUs, boolean forceReset) {
     Assertions.checkState(prepared);
-    int oldEnabledSampleQueueCount = enabledSampleQueueCount;
+    int oldEnabledTrackGroupCount = enabledTrackGroupCount;
     // Deselect old tracks.
     for (int i = 0; i < selections.length; i++) {
       if (streams[i] != null && (selections[i] == null || !mayRetainStreamFlags[i])) {
-        setSampleQueueEnabledState(((HlsSampleStream) streams[i]).sampleQueueIndex, false);
+        enabledTrackGroupCount--;
+        ((HlsSampleStream) streams[i]).unbindSampleQueue();
         streams[i] = null;
       }
     }
     // We'll always need to seek if we're being forced to reset, or if this is a first selection to
     // a position other than the one we started preparing with, or if we're making a selection
     // having previously disabled all tracks.
-    boolean seekRequired = forceReset
-        || (seenFirstTrackSelection ? oldEnabledSampleQueueCount == 0
-            : positionUs != lastSeekPositionUs);
+    boolean seekRequired =
+        forceReset
+            || (seenFirstTrackSelection
+                ? oldEnabledTrackGroupCount == 0
+                : positionUs != lastSeekPositionUs);
     // Get the old (i.e. current before the loop below executes) primary track selection. The new
     // primary selection will equal the old one unless it's changed in the loop.
     TrackSelection oldPrimaryTrackSelection = chunkSource.getTrackSelection();
@@ -219,19 +247,18 @@ import java.util.Arrays;
     // Select new tracks.
     for (int i = 0; i < selections.length; i++) {
       if (streams[i] == null && selections[i] != null) {
+        enabledTrackGroupCount++;
         TrackSelection selection = selections[i];
         int trackGroupIndex = trackGroups.indexOf(selection.getTrackGroup());
-        int sampleQueueIndex = trackGroupToSampleQueueIndex[trackGroupIndex];
-        setSampleQueueEnabledState(sampleQueueIndex, true);
         if (trackGroupIndex == primaryTrackGroupIndex) {
           primaryTrackSelection = selection;
           chunkSource.selectTracks(selection);
         }
-        streams[i] = new HlsSampleStream(this, sampleQueueIndex);
+        streams[i] = new HlsSampleStream(this, trackGroupIndex);
         streamResetFlags[i] = true;
         // If there's still a chance of avoiding a seek, try and seek within the sample queue.
-        if (!seekRequired) {
-          SampleQueue sampleQueue = sampleQueues[sampleQueueIndex];
+        if (sampleQueuesBuilt && !seekRequired) {
+          SampleQueue sampleQueue = sampleQueues[trackGroupToSampleQueueIndex[trackGroupIndex]];
           sampleQueue.rewind();
           // A seek can be avoided if we're able to advance to the current playback position in the
           // sample queue, or if we haven't read anything from the queue since the previous seek
@@ -243,14 +270,16 @@ import java.util.Arrays;
       }
     }
 
-    if (enabledSampleQueueCount == 0) {
+    if (enabledTrackGroupCount == 0) {
       chunkSource.reset();
       downstreamTrackFormat = null;
       mediaChunks.clear();
       if (loader.isLoading()) {
-        // Discard as much as we can synchronously.
-        for (SampleQueue sampleQueue : sampleQueues) {
-          sampleQueue.discardToEnd();
+        if (sampleQueuesBuilt) {
+          // Discard as much as we can synchronously.
+          for (SampleQueue sampleQueue : sampleQueues) {
+            sampleQueue.discardToEnd();
+          }
         }
         loader.cancelLoading();
       } else {
@@ -297,6 +326,9 @@ import java.util.Arrays;
   }
 
   public void discardBuffer(long positionUs, boolean toKeyframe) {
+    if (!sampleQueuesBuilt) {
+      return;
+    }
     int sampleQueueCount = sampleQueues.length;
     for (int i = 0; i < sampleQueueCount; i++) {
       sampleQueues[i].discardTo(positionUs, toKeyframe, sampleQueuesEnabledStates[i]);
@@ -314,7 +346,7 @@ import java.util.Arrays;
   public boolean seekToUs(long positionUs, boolean forceReset) {
     lastSeekPositionUs = positionUs;
     // If we're not forced to reset nor have a pending reset, see if we can seek within the buffer.
-    if (!forceReset && !isPendingReset() && seekInsideBufferUs(positionUs)) {
+    if (sampleQueuesBuilt && !forceReset && !isPendingReset() && seekInsideBufferUs(positionUs)) {
       return false;
     }
     // We were unable to seek within the buffer, so need to reset.
@@ -426,9 +458,11 @@ import java.util.Arrays;
       if (lastCompletedMediaChunk != null) {
         bufferedPositionUs = Math.max(bufferedPositionUs, lastCompletedMediaChunk.endTimeUs);
       }
-      for (SampleQueue sampleQueue : sampleQueues) {
-        bufferedPositionUs = Math.max(bufferedPositionUs,
-            sampleQueue.getLargestQueuedTimestampUs());
+      if (sampleQueuesBuilt) {
+        for (SampleQueue sampleQueue : sampleQueues) {
+          bufferedPositionUs =
+              Math.max(bufferedPositionUs, sampleQueue.getLargestQueuedTimestampUs());
+        }
       }
       return bufferedPositionUs;
     }
@@ -513,7 +547,7 @@ import java.util.Arrays;
         loadable.endTimeUs, elapsedRealtimeMs, loadDurationMs, loadable.bytesLoaded());
     if (!released) {
       resetSampleQueues();
-      if (enabledSampleQueueCount > 0) {
+      if (enabledTrackGroupCount > 0) {
         callback.onContinueLoadingRequested(this);
       }
     }
@@ -582,7 +616,7 @@ import java.util.Arrays;
         return sampleQueues[i];
       }
     }
-    if (sampleQueuesBuilt) {
+    if (tracksEnded) {
       Log.w(TAG, "Unmapped track with id " + id + " of type " + type);
       return new DummyTrackOutput();
     }
@@ -603,8 +637,8 @@ import java.util.Arrays;
 
   @Override
   public void endTracks() {
-    sampleQueuesBuilt = true;
-    handler.post(maybeFinishPrepareRunnable);
+    tracksEnded = true;
+    handler.post(onTracksEndedRunnable);
   }
 
   @Override
@@ -616,9 +650,7 @@ import java.util.Arrays;
 
   @Override
   public void onUpstreamFormatChanged(Format format) {
-    if (!prepared) {
-      handler.post(maybeFinishPrepareRunnable);
-    }
+    handler.post(maybeFinishPrepareRunnable);
   }
 
   // Called by the loading thread.
@@ -650,6 +682,11 @@ import java.util.Arrays;
     pendingResetUpstreamFormats = false;
   }
 
+  private void onTracksEnded() {
+    sampleQueuesBuilt = true;
+    maybeFinishPrepare();
+  }
+
   private void maybeFinishPrepare() {
     if (released || prepared || !sampleQueuesBuilt) {
       return;
@@ -739,14 +776,14 @@ import java.util.Arrays;
       if (i == primaryExtractorTrackIndex) {
         Format[] formats = new Format[chunkSourceTrackCount];
         for (int j = 0; j < chunkSourceTrackCount; j++) {
-          formats[j] = deriveFormat(chunkSourceTrackGroup.getFormat(j), sampleFormat);
+          formats[j] = deriveFormat(chunkSourceTrackGroup.getFormat(j), sampleFormat, true);
         }
         trackGroups[i] = new TrackGroup(formats);
         primaryTrackGroupIndex = i;
       } else {
         Format trackFormat = primaryExtractorTrackType == PRIMARY_TYPE_VIDEO
             && MimeTypes.isAudio(sampleFormat.sampleMimeType) ? muxedAudioFormat : null;
-        trackGroups[i] = new TrackGroup(deriveFormat(trackFormat, sampleFormat));
+        trackGroups[i] = new TrackGroup(deriveFormat(trackFormat, sampleFormat, false));
       }
     }
     this.trackGroups = new TrackGroupArray(trackGroups);
@@ -761,7 +798,6 @@ import java.util.Arrays;
   private void setSampleQueueEnabledState(int sampleQueueIndex, boolean enabledState) {
     Assertions.checkState(sampleQueuesEnabledStates[sampleQueueIndex] != enabledState);
     sampleQueuesEnabledStates[sampleQueueIndex] = enabledState;
-    enabledSampleQueueCount = enabledSampleQueueCount + (enabledState ? 1 : -1);
   }
 
   private HlsMediaChunk getLastMediaChunk() {
@@ -797,22 +833,30 @@ import java.util.Arrays;
   }
 
   /**
-   * Derives a track format corresponding to a given container format, by combining it with sample
-   * level information obtained from the samples.
+   * Derives a track format using master playlist and sample format information.
    *
-   * @param containerFormat The container format for which the track format should be derived.
-   * @param sampleFormat A sample format from which to obtain sample level information.
+   * @param playlistFormat The format information obtained from the master playlist.
+   * @param sampleFormat The format information obtained from the samples.
+   * @param propagateBitrate Whether the bitrate from the playlist format should be included in the
+   *     derived format.
    * @return The derived track format.
    */
-  private static Format deriveFormat(Format containerFormat, Format sampleFormat) {
-    if (containerFormat == null) {
+  private static Format deriveFormat(
+      Format playlistFormat, Format sampleFormat, boolean propagateBitrate) {
+    if (playlistFormat == null) {
       return sampleFormat;
     }
+    int bitrate = propagateBitrate ? playlistFormat.bitrate : Format.NO_VALUE;
     int sampleTrackType = MimeTypes.getTrackType(sampleFormat.sampleMimeType);
-    String codecs = Util.getCodecsOfType(containerFormat.codecs, sampleTrackType);
-    return sampleFormat.copyWithContainerInfo(containerFormat.id, codecs, containerFormat.bitrate,
-        containerFormat.width, containerFormat.height, containerFormat.selectionFlags,
-        containerFormat.language);
+    String codecs = Util.getCodecsOfType(playlistFormat.codecs, sampleTrackType);
+    return sampleFormat.copyWithContainerInfo(
+        playlistFormat.id,
+        codecs,
+        bitrate,
+        playlistFormat.width,
+        playlistFormat.height,
+        playlistFormat.selectionFlags,
+        playlistFormat.language);
   }
 
   private static boolean isMediaChunk(Chunk chunk) {

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/SampleQueueMappingException.java

+/*
+ * Copyright (C) 2017 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.hls;
+
+import com.google.android.exoplayer2.source.SampleQueue;
+import com.google.android.exoplayer2.source.TrackGroup;
+import java.io.IOException;
+
+/** Thrown when it is not possible to map a {@link TrackGroup} to a {@link SampleQueue}. */
+public final class SampleQueueMappingException extends IOException {
+
+  /** @param mimeType The mime type of the track group whose mapping failed. */
+  public SampleQueueMappingException(String mimeType) {
+    super("Unable to bind a sample queue to TrackGroup with mime type " + mimeType + ".");
+  }
+}