Enable track selection + WebVTT for HLS.

See the documentation of buildTracks for the gory details.

Issue: #151
Issue: #676
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=112149293

demo/src/main/java/com/google/android/exoplayer/demo/player/HlsRendererBuilder.java

@@ -25,12 +25,14 @@ import com.google.android.exoplayer.audio.AudioCapabilities;
 import com.google.android.exoplayer.demo.player.DemoPlayer.RendererBuilder;
 import com.google.android.exoplayer.hls.DefaultHlsTrackSelector;
 import com.google.android.exoplayer.hls.HlsChunkSource;
+import com.google.android.exoplayer.hls.HlsMasterPlaylist;
 import com.google.android.exoplayer.hls.HlsPlaylist;
 import com.google.android.exoplayer.hls.HlsPlaylistParser;
 import com.google.android.exoplayer.hls.HlsSampleSource;
 import com.google.android.exoplayer.hls.PtsTimestampAdjusterProvider;
 import com.google.android.exoplayer.metadata.Id3Parser;
 import com.google.android.exoplayer.metadata.MetadataTrackRenderer;
+import com.google.android.exoplayer.text.TextTrackRenderer;
 import com.google.android.exoplayer.text.eia608.Eia608TrackRenderer;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
@@ -53,7 +55,8 @@ import java.util.Map;
 public class HlsRendererBuilder implements RendererBuilder {
 
   private static final int BUFFER_SEGMENT_SIZE = 64 * 1024;
-  private static final int BUFFER_SEGMENTS = 256;
+  private static final int MAIN_BUFFER_SEGMENTS = 256;
+  private static final int TEXT_BUFFER_SEGMENTS = 2;
 
   private final Context context;
   private final String userAgent;
@@ -127,13 +130,15 @@ public class HlsRendererBuilder implements RendererBuilder {
       Handler mainHandler = player.getMainHandler();
       LoadControl loadControl = new DefaultLoadControl(new DefaultAllocator(BUFFER_SEGMENT_SIZE));
       DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
+      PtsTimestampAdjusterProvider timestampAdjusterProvider = new PtsTimestampAdjusterProvider();
 
+      // Build the video/audio/metadata renderers.
       DataSource dataSource = new DefaultUriDataSource(context, bandwidthMeter, userAgent);
       HlsChunkSource chunkSource = new HlsChunkSource(true /* isMaster */, dataSource, url,
           manifest, DefaultHlsTrackSelector.newDefaultInstance(context), bandwidthMeter,
-          new PtsTimestampAdjusterProvider(), HlsChunkSource.ADAPTIVE_MODE_SPLICE);
+          timestampAdjusterProvider, HlsChunkSource.ADAPTIVE_MODE_SPLICE);
       HlsSampleSource sampleSource = new HlsSampleSource(chunkSource, loadControl,
-          BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, mainHandler, player, DemoPlayer.TYPE_VIDEO);
+          MAIN_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, mainHandler, player, DemoPlayer.TYPE_VIDEO);
       MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(context,
           sampleSource, MediaCodecSelector.DEFAULT, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT,
           5000, mainHandler, player, 50);
@@ -142,14 +147,30 @@ public class HlsRendererBuilder implements RendererBuilder {
           AudioCapabilities.getCapabilities(context), AudioManager.STREAM_MUSIC);
       MetadataTrackRenderer<Map<String, Object>> id3Renderer = new MetadataTrackRenderer<>(
           sampleSource, new Id3Parser(), player, mainHandler.getLooper());
-      Eia608TrackRenderer closedCaptionRenderer = new Eia608TrackRenderer(sampleSource, player,
-          mainHandler.getLooper());
+
+      // Build the text renderer, preferring Webvtt where available.
+      boolean preferWebvtt = false;
+      if (manifest instanceof HlsMasterPlaylist) {
+        preferWebvtt = !((HlsMasterPlaylist) manifest).subtitles.isEmpty();
+      }
+      TrackRenderer textRenderer;
+      if (preferWebvtt) {
+        DataSource textDataSource = new DefaultUriDataSource(context, bandwidthMeter, userAgent);
+        HlsChunkSource textChunkSource = new HlsChunkSource(false /* isMaster */, textDataSource,
+            url, manifest, DefaultHlsTrackSelector.newVttInstance(), bandwidthMeter,
+            timestampAdjusterProvider, HlsChunkSource.ADAPTIVE_MODE_SPLICE);
+        HlsSampleSource textSampleSource = new HlsSampleSource(textChunkSource, loadControl,
+            TEXT_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, mainHandler, player, DemoPlayer.TYPE_TEXT);
+        textRenderer = new TextTrackRenderer(textSampleSource, player, mainHandler.getLooper());
+      } else {
+        textRenderer = new Eia608TrackRenderer(sampleSource, player, mainHandler.getLooper());
+      }
 
       TrackRenderer[] renderers = new TrackRenderer[DemoPlayer.RENDERER_COUNT];
       renderers[DemoPlayer.TYPE_VIDEO] = videoRenderer;
       renderers[DemoPlayer.TYPE_AUDIO] = audioRenderer;
       renderers[DemoPlayer.TYPE_METADATA] = id3Renderer;
-      renderers[DemoPlayer.TYPE_TEXT] = closedCaptionRenderer;
+      renderers[DemoPlayer.TYPE_TEXT] = textRenderer;
       player.onRenderers(renderers, bandwidthMeter);
     }
 

library/src/main/java/com/google/android/exoplayer/MediaFormat.java

@@ -234,6 +234,13 @@ public final class MediaFormat {
         subsampleOffsetUs, initializationData, adaptive, maxWidth, maxHeight);
   }
 
+  public MediaFormat copyWithFixedTrackInfo(String trackId, int bitrate, int width, int height,
+      String language) {
+    return new MediaFormat(trackId, mimeType, bitrate, maxInputSize, durationUs, width, height,
+        rotationDegrees, pixelWidthHeightRatio, channelCount, sampleRate, language,
+        subsampleOffsetUs, initializationData, adaptive, NO_VALUE, NO_VALUE);
+  }
+
   public MediaFormat copyAsAdaptive(String trackId) {
     return new MediaFormat(trackId, mimeType, NO_VALUE, NO_VALUE, durationUs, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE, null, OFFSET_SAMPLE_RELATIVE, null, true, maxWidth,

library/src/main/java/com/google/android/exoplayer/hls/HlsChunkSource.java

@@ -133,7 +133,7 @@ public class HlsChunkSource implements HlsTrackSelector.Output {
   // TODO: Expose tracks.
   private final ArrayList<ExposedTrack> tracks;
 
-  private ExposedTrack enabledTrack;
+  private int selectedTrackIndex;
 
   // A list of variants considered during playback, ordered by decreasing bandwidth. The following
   // three arrays are of the same length and are ordered in the same way (i.e. variantPlaylists[i],
@@ -295,6 +295,18 @@ public class HlsChunkSource implements HlsTrackSelector.Output {
     return variants.length == 1 ? variants[0] : null;
   }
 
+
+  /**
+   * Returns the currently selected track index.
+   * <p>
+   * This method should only be called after the source has been prepared.
+   *
+   * @return The currently selected track index.
+   */
+  public int getSelectedTrackIndex() {
+    return selectedTrackIndex;
+  }
+
   /**
    * Selects a track for use.
    * <p>
@@ -303,9 +315,10 @@ public class HlsChunkSource implements HlsTrackSelector.Output {
    * @param index The track index.
    */
   public void selectTrack(int index) {
-    enabledTrack = tracks.get(index);
-    selectedVariantIndex = enabledTrack.defaultVariantIndex;
-    variants = enabledTrack.variants;
+    selectedTrackIndex = index;
+    ExposedTrack selectedTrack = tracks.get(selectedTrackIndex);
+    selectedVariantIndex = selectedTrack.defaultVariantIndex;
+    variants = selectedTrack.variants;
     variantPlaylists = new HlsMediaPlaylist[variants.length];
     variantLastPlaylistLoadTimesMs = new long[variants.length];
     variantBlacklistTimes = new long[variants.length];
@@ -472,9 +485,10 @@ public class HlsChunkSource implements HlsTrackSelector.Output {
         // The master source has yet to instantiate an adjuster for the discontinuity sequence.
         return;
       }
+      ExposedTrack selectedTrack = tracks.get(selectedTrackIndex);
       Extractor extractor = new TsExtractor(timestampAdjuster);
       extractorWrapper = new HlsExtractorWrapper(trigger, format, startTimeUs, extractor,
-          switchingVariantSpliced, enabledTrack.adaptiveMaxWidth, enabledTrack.adaptiveMaxHeight);
+          switchingVariantSpliced, selectedTrack.adaptiveMaxWidth, selectedTrack.adaptiveMaxHeight);
     } else {
       // MPEG-2 TS segments, and we need to continue using the same extractor.
       extractorWrapper = previousTsChunk.extractorWrapper;