Chose timestamp adjustment master based on track selection

Select the timestamp master depending on track availability. If
a variant is being loaded, then that is the timestmap master.
Otherwise, if an audio track is being loaded, then the responsible
chunk source is the timestmap master. If no variant or audio
rendition is enabled, then a subtitle chunk source is selected as
timestamp master. This CL will become specially relevant once
ID3 PRIV timestamps are used for audio renditions.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=140201385

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

@@ -103,6 +103,7 @@ import java.util.Locale;
   private final HlsPlaylistTracker playlistTracker;
   private final TrackGroup trackGroup;
 
+  private boolean isTimestampMaster;
   private byte[] scratchSpace;
   private IOException fatalError;
 
@@ -177,6 +178,16 @@ import java.util.Locale;
   }
 
   /**
+   * Sets whether this chunk source is responsible for initializing timestamp adjusters.
+   *
+   * @param isTimestampMaster True if this chunk source is responsible for initializing timestamp
+   *     adjusters.
+   */
+  public void setIsTimestampMaster(boolean isTimestampMaster) {
+    this.isTimestampMaster = isTimestampMaster;
+  }
+
+  /**
    * Returns the next chunk to load.
    * <p>
    * If a chunk is available then {@link HlsChunkHolder#chunk} is set. If the end of the stream has
@@ -280,7 +291,6 @@ import java.util.Locale;
         || previous.discontinuitySequenceNumber != segment.discontinuitySequenceNumber
         || format != previous.trackFormat;
     boolean extractorNeedsInit = true;
-    boolean isTimestampMaster = false;
     TimestampAdjuster timestampAdjuster = null;
     String lastPathSegment = chunkUri.getLastPathSegment();
     if (lastPathSegment.endsWith(AAC_FILE_EXTENSION)) {
@@ -299,7 +309,6 @@ import java.util.Locale;
           startTimeUs);
       extractor = new WebvttExtractor(format.language, timestampAdjuster);
     } else if (lastPathSegment.endsWith(MP4_FILE_EXTENSION)) {
-      isTimestampMaster = true;
       if (needNewExtractor) {
         timestampAdjuster = timestampAdjusterProvider.getAdjuster(
             segment.discontinuitySequenceNumber, startTimeUs);
@@ -310,7 +319,6 @@ import java.util.Locale;
       }
     } else if (needNewExtractor) {
       // MPEG-2 TS segments, but we need a new extractor.
-      isTimestampMaster = true;
       timestampAdjuster = timestampAdjusterProvider.getAdjuster(
           segment.discontinuitySequenceNumber, startTimeUs);
       // This flag ensures the change of pid between streams does not affect the sample queues.

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

@@ -26,6 +26,7 @@ import com.google.android.exoplayer2.source.SampleStream;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMasterPlaylist;
+import com.google.android.exoplayer2.source.hls.playlist.HlsMasterPlaylist.HlsUrl;
 import com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
@@ -166,6 +167,18 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
     // Update the local state.
     enabledSampleStreamWrappers = new HlsSampleStreamWrapper[enabledSampleStreamWrapperList.size()];
     enabledSampleStreamWrapperList.toArray(enabledSampleStreamWrappers);
+
+    // The first enabled sample stream wrapper is responsible for intializing the timestamp
+    // adjuster. This way, if present, variants are responsible. Otherwise, audio renditions are.
+    // If only subtitles are present, then text renditions are used for timestamp adjustment
+    // initialization.
+    if (enabledSampleStreamWrappers.length > 0) {
+      enabledSampleStreamWrappers[0].setIsTimestampMaster(true);
+      for (int i = 1; i < enabledSampleStreamWrappers.length; i++) {
+        enabledSampleStreamWrappers[i].setIsTimestampMaster(false);
+      }
+    }
+
     sequenceableLoader = new CompositeSequenceableLoader(enabledSampleStreamWrappers);
     if (seenFirstTrackSelection && selectedNewTracks) {
       seekToUs(positionUs);
@@ -241,7 +254,7 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
   }
 
   @Override
-  public void onPlaylistRefreshRequired(HlsMasterPlaylist.HlsUrl url) {
+  public void onPlaylistRefreshRequired(HlsUrl url) {
     playlistTracker.refreshPlaylist(url, this);
   }
 
@@ -269,7 +282,7 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
   }
 
   @Override
-  public void onPlaylistLoadError(HlsMasterPlaylist.HlsUrl url, IOException error) {
+  public void onPlaylistLoadError(HlsUrl url, IOException error) {
     for (HlsSampleStreamWrapper sampleStreamWrapper : enabledSampleStreamWrappers) {
       sampleStreamWrapper.onPlaylistLoadError(url, error);
     }
@@ -281,11 +294,11 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
   private void buildAndPrepareSampleStreamWrappers() {
     HlsMasterPlaylist masterPlaylist = playlistTracker.getMasterPlaylist();
     // Build the default stream wrapper.
-    List<HlsMasterPlaylist.HlsUrl> selectedVariants = new ArrayList<>(masterPlaylist.variants);
-    ArrayList<HlsMasterPlaylist.HlsUrl> definiteVideoVariants = new ArrayList<>();
-    ArrayList<HlsMasterPlaylist.HlsUrl> definiteAudioOnlyVariants = new ArrayList<>();
+    List<HlsUrl> selectedVariants = new ArrayList<>(masterPlaylist.variants);
+    ArrayList<HlsUrl> definiteVideoVariants = new ArrayList<>();
+    ArrayList<HlsUrl> definiteAudioOnlyVariants = new ArrayList<>();
     for (int i = 0; i < selectedVariants.size(); i++) {
-      HlsMasterPlaylist.HlsUrl variant = selectedVariants.get(i);
+      HlsUrl variant = selectedVariants.get(i);
       if (variant.format.height > 0 || variantHasExplicitCodecWithPrefix(variant, "avc")) {
         definiteVideoVariants.add(variant);
       } else if (variantHasExplicitCodecWithPrefix(variant, "mp4a")) {
@@ -304,41 +317,44 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
     } else {
       // Leave the enabled variants unchanged. They're likely either all video or all audio.
     }
-    List<HlsMasterPlaylist.HlsUrl> audioVariants = masterPlaylist.audios;
-    List<HlsMasterPlaylist.HlsUrl> subtitleVariants = masterPlaylist.subtitles;
-    sampleStreamWrappers = new HlsSampleStreamWrapper[(selectedVariants.isEmpty() ? 0 : 1)
-        + audioVariants.size() + subtitleVariants.size()];
+    List<HlsUrl> audioRenditions = masterPlaylist.audios;
+    List<HlsUrl> subtitleRenditions = masterPlaylist.subtitles;
+    sampleStreamWrappers = new HlsSampleStreamWrapper[1 /* variants */ + audioRenditions.size()
+        + subtitleRenditions.size()];
     int currentWrapperIndex = 0;
     pendingPrepareCount = sampleStreamWrappers.length;
-    if (!selectedVariants.isEmpty()) {
-      HlsMasterPlaylist.HlsUrl[] variants = new HlsMasterPlaylist.HlsUrl[selectedVariants.size()];
-      selectedVariants.toArray(variants);
-      HlsSampleStreamWrapper sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_DEFAULT,
-          variants, masterPlaylist.muxedAudioFormat, masterPlaylist.muxedCaptionFormat);
-      sampleStreamWrappers[currentWrapperIndex++] = sampleStreamWrapper;
-      sampleStreamWrapper.continuePreparing();
-    }
+
+    Assertions.checkArgument(!selectedVariants.isEmpty());
+    HlsUrl[] variants = new HlsMasterPlaylist.HlsUrl[selectedVariants.size()];
+    selectedVariants.toArray(variants);
+    HlsSampleStreamWrapper sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_DEFAULT,
+        variants, masterPlaylist.muxedAudioFormat, masterPlaylist.muxedCaptionFormat);
+    sampleStreamWrappers[currentWrapperIndex++] = sampleStreamWrapper;
+    sampleStreamWrapper.setIsTimestampMaster(true);
+    sampleStreamWrapper.continuePreparing();
+
+    // TODO: Build video stream wrappers here.
 
     // Build audio stream wrappers.
-    for (int i = 0; i < audioVariants.size(); i++) {
-      HlsSampleStreamWrapper sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_AUDIO,
-          new HlsMasterPlaylist.HlsUrl[] {audioVariants.get(i)}, null, null);
+    for (int i = 0; i < audioRenditions.size(); i++) {
+      sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_AUDIO,
+          new HlsUrl[] {audioRenditions.get(i)}, null, null);
       sampleStreamWrappers[currentWrapperIndex++] = sampleStreamWrapper;
       sampleStreamWrapper.continuePreparing();
     }
 
     // Build subtitle stream wrappers.
-    for (int i = 0; i < subtitleVariants.size(); i++) {
-      HlsMasterPlaylist.HlsUrl url = subtitleVariants.get(i);
-      HlsSampleStreamWrapper sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_TEXT,
-          new HlsMasterPlaylist.HlsUrl[] {url}, null, null);
+    for (int i = 0; i < subtitleRenditions.size(); i++) {
+      HlsUrl url = subtitleRenditions.get(i);
+      sampleStreamWrapper = buildSampleStreamWrapper(C.TRACK_TYPE_TEXT, new HlsUrl[] {url}, null,
+          null);
       sampleStreamWrapper.prepareSingleTrack(url.format);
       sampleStreamWrappers[currentWrapperIndex++] = sampleStreamWrapper;
     }
   }
 
-  private HlsSampleStreamWrapper buildSampleStreamWrapper(int trackType,
-      HlsMasterPlaylist.HlsUrl[] variants, Format muxedAudioFormat, Format muxedCaptionFormat) {
+  private HlsSampleStreamWrapper buildSampleStreamWrapper(int trackType, HlsUrl[] variants,
+      Format muxedAudioFormat, Format muxedCaptionFormat) {
     DataSource dataSource = dataSourceFactory.createDataSource();
     HlsChunkSource defaultChunkSource = new HlsChunkSource(playlistTracker, variants, dataSource,
         timestampAdjusterProvider);
@@ -347,8 +363,7 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
         eventDispatcher);
   }
 
-  private static boolean variantHasExplicitCodecWithPrefix(HlsMasterPlaylist.HlsUrl variant,
-      String prefix) {
+  private static boolean variantHasExplicitCodecWithPrefix(HlsUrl variant, String prefix) {
     String codecs = variant.format.codecs;
     if (TextUtils.isEmpty(codecs)) {
       return false;

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

@@ -275,6 +275,10 @@ import java.util.LinkedList;
     return largestQueuedTimestampUs;
   }
 
+  public void setIsTimestampMaster(boolean isTimestampMaster) {
+    chunkSource.setIsTimestampMaster(isTimestampMaster);
+  }
+
   public void onPlaylistLoadError(HlsUrl url, IOException error) {
     chunkSource.onPlaylistLoadError(url, error);
   }