HLS: More control over buffering + tweak caption impl.

- Move all three buffering constants to a single class (the
  chunk source).
- Increase the target buffer to 40s for increased robustness
  against temporary network blips.
- Make values configurable via the chunk source constructor.
- Treat captions as a text track for HLS. This allows them to
  be enabled/disabled through the demo app UI.

Issue: #165

demo/src/main/java/com/google/android/exoplayer/demo/full/FullPlayerActivity.java

@@ -25,7 +25,6 @@ import com.google.android.exoplayer.demo.full.player.DemoPlayer;
 import com.google.android.exoplayer.demo.full.player.DemoPlayer.RendererBuilder;
 import com.google.android.exoplayer.demo.full.player.HlsRendererBuilder;
 import com.google.android.exoplayer.demo.full.player.SmoothStreamingRendererBuilder;
-import com.google.android.exoplayer.metadata.ClosedCaption;
 import com.google.android.exoplayer.metadata.TxxxMetadata;
 import com.google.android.exoplayer.text.CaptionStyleCompat;
 import com.google.android.exoplayer.text.SubtitleView;
@@ -57,15 +56,13 @@ import android.widget.PopupMenu;
 import android.widget.PopupMenu.OnMenuItemClickListener;
 import android.widget.TextView;
 
-import java.util.List;
 import java.util.Map;
 
 /**
  * An activity that plays media using {@link DemoPlayer}.
  */
 public class FullPlayerActivity extends Activity implements SurfaceHolder.Callback, OnClickListener,
-    DemoPlayer.Listener, DemoPlayer.TextListener, DemoPlayer.Id3MetadataListener,
+    DemoPlayer.Listener, DemoPlayer.TextListener, DemoPlayer.Id3MetadataListener {
-    DemoPlayer.ClosedCaptionListener {
 
   private static final String TAG = "FullPlayerActivity";
 
@@ -198,7 +195,6 @@ public class FullPlayerActivity extends Activity implements SurfaceHolder.Callba
       player.addListener(this);
       player.setTextListener(this);
       player.setMetadataListener(this);
-      player.setClosedCaptionListener(this);
       player.seekTo(playerPosition);
       playerNeedsPrepare = true;
       mediaController.setMediaPlayer(player.getPlayerControl());
@@ -428,31 +424,6 @@ public class FullPlayerActivity extends Activity implements SurfaceHolder.Callba
     }
   }
 
-  // DemoPlayer.ClosedCaptioListener implementation
-
-  @Override
-  public void onClosedCaption(List<ClosedCaption> closedCaptions) {
-    StringBuilder stringBuilder = new StringBuilder();
-    for (ClosedCaption caption : closedCaptions) {
-      // Ignore control characters and just insert a new line in between words.
-      if (caption.type == ClosedCaption.TYPE_CTRL) {
-        if (stringBuilder.length() > 0
-            && stringBuilder.charAt(stringBuilder.length() - 1) != '\n') {
-          stringBuilder.append('\n');
-        }
-      } else if (caption.type == ClosedCaption.TYPE_TEXT) {
-        stringBuilder.append(caption.text);
-      }
-    }
-    if (stringBuilder.length() > 0 && stringBuilder.charAt(stringBuilder.length() - 1) == '\n') {
-      stringBuilder.deleteCharAt(stringBuilder.length() - 1);
-    }
-    if (stringBuilder.length() > 0) {
-      subtitleView.setVisibility(View.VISIBLE);
-      subtitleView.setText(stringBuilder.toString());
-    }
-  }
-
   // SurfaceHolder.Callback implementation
 
   @Override

demo/src/main/java/com/google/android/exoplayer/demo/full/player/DemoPlayer.java

@@ -145,13 +145,6 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
     void onId3Metadata(Map<String, Object> metadata);
   }
 
-  /**
-   * A listener for receiving closed captions parsed from the media stream.
-   */
-  public interface ClosedCaptionListener {
-    void onClosedCaption(List<ClosedCaption> closedCaptions);
-  }
-
   // Constants pulled into this class for convenience.
   public static final int STATE_IDLE = ExoPlayer.STATE_IDLE;
   public static final int STATE_PREPARING = ExoPlayer.STATE_PREPARING;
@@ -162,13 +155,12 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
   public static final int DISABLED_TRACK = -1;
   public static final int PRIMARY_TRACK = 0;
 
-  public static final int RENDERER_COUNT = 6;
+  public static final int RENDERER_COUNT = 5;
   public static final int TYPE_VIDEO = 0;
   public static final int TYPE_AUDIO = 1;
   public static final int TYPE_TEXT = 2;
   public static final int TYPE_TIMED_METADATA = 3;
-  public static final int TYPE_CLOSED_CAPTIONS = 4;
+  public static final int TYPE_DEBUG = 4;
-  public static final int TYPE_DEBUG = 5;
 
   private static final int RENDERER_BUILDING_STATE_IDLE = 1;
   private static final int RENDERER_BUILDING_STATE_BUILDING = 2;
@@ -179,6 +171,7 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
   private final PlayerControl playerControl;
   private final Handler mainHandler;
   private final CopyOnWriteArrayList<Listener> listeners;
+  private final StringBuilder closedCaptionStringBuilder;
 
   private int rendererBuildingState;
   private int lastReportedPlaybackState;
@@ -194,7 +187,6 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
 
   private TextListener textListener;
   private Id3MetadataListener id3MetadataListener;
-  private ClosedCaptionListener closedCaptionListener;
   private InternalErrorListener internalErrorListener;
   private InfoListener infoListener;
 
@@ -210,6 +202,7 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
     selectedTracks = new int[RENDERER_COUNT];
     // Disable text initially.
     selectedTracks[TYPE_TEXT] = DISABLED_TRACK;
+    closedCaptionStringBuilder = new StringBuilder();
   }
 
   public PlayerControl getPlayerControl() {
@@ -240,10 +233,6 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
     id3MetadataListener = listener;
   }
 
-  public void setClosedCaptionListener(ClosedCaptionListener listener) {
-    closedCaptionListener = listener;
-  }
-
   public void setSurface(Surface surface) {
     this.surface = surface;
     pushSurfaceAndVideoTrack(false);
@@ -275,6 +264,9 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
       pushSurfaceAndVideoTrack(false);
     } else {
       pushTrackSelection(type, true);
+      if (type == TYPE_TEXT && index == DISABLED_TRACK && textListener != null) {
+        textListener.onText(null);
+      }
     }
   }
 
@@ -483,36 +475,28 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
 
   @Override
   public void onText(String text) {
-    if (textListener != null) {
+    processText(text);
-      textListener.onText(text);
-    }
   }
 
   /* package */ MetadataTrackRenderer.MetadataRenderer<Map<String, Object>>
       getId3MetadataRenderer() {
     return new MetadataTrackRenderer.MetadataRenderer<Map<String, Object>>() {
-
       @Override
       public void onMetadata(Map<String, Object> metadata) {
         if (id3MetadataListener != null) {
           id3MetadataListener.onId3Metadata(metadata);
         }
       }
-
     };
   }
 
   /* package */ MetadataTrackRenderer.MetadataRenderer<List<ClosedCaption>>
       getClosedCaptionMetadataRenderer() {
     return new MetadataTrackRenderer.MetadataRenderer<List<ClosedCaption>>() {
-
       @Override
       public void onMetadata(List<ClosedCaption> metadata) {
-        if (closedCaptionListener != null) {
+        processClosedCaption(metadata);
-          closedCaptionListener.onClosedCaption(metadata);
       }
-      }
-
     };
   }
 
@@ -607,6 +591,36 @@ public class DemoPlayer implements ExoPlayer.Listener, ChunkSampleSource.EventLi
     }
   }
 
+  /* package */ void processText(String text) {
+    if (textListener == null || selectedTracks[TYPE_TEXT] == DISABLED_TRACK) {
+      return;
+    }
+    textListener.onText(text);
+  }
+
+  /* package */ void processClosedCaption(List<ClosedCaption> metadata) {
+    if (textListener == null || selectedTracks[TYPE_TEXT] == DISABLED_TRACK) {
+      return;
+    }
+    closedCaptionStringBuilder.setLength(0);
+    for (ClosedCaption caption : metadata) {
+      // Ignore control characters and just insert a new line in between words.
+      if (caption.type == ClosedCaption.TYPE_CTRL) {
+        if (closedCaptionStringBuilder.length() > 0
+            && closedCaptionStringBuilder.charAt(closedCaptionStringBuilder.length() - 1) != '\n') {
+          closedCaptionStringBuilder.append('\n');
+        }
+      } else if (caption.type == ClosedCaption.TYPE_TEXT) {
+        closedCaptionStringBuilder.append(caption.text);
+      }
+    }
+    if (closedCaptionStringBuilder.length() > 0
+        && closedCaptionStringBuilder.charAt(closedCaptionStringBuilder.length() - 1) == '\n') {
+      closedCaptionStringBuilder.deleteCharAt(closedCaptionStringBuilder.length() - 1);
+    }
+    textListener.onText(closedCaptionStringBuilder.toString());
+  }
+
   private class InternalRendererBuilderCallback implements RendererBuilderCallback {
 
     private boolean canceled;

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

@@ -100,7 +100,7 @@ public class HlsRendererBuilder implements RendererBuilder, ManifestCallback<Hls
     renderers[DemoPlayer.TYPE_VIDEO] = videoRenderer;
     renderers[DemoPlayer.TYPE_AUDIO] = audioRenderer;
     renderers[DemoPlayer.TYPE_TIMED_METADATA] = id3Renderer;
-    renderers[DemoPlayer.TYPE_CLOSED_CAPTIONS] = closedCaptionRenderer;
+    renderers[DemoPlayer.TYPE_TEXT] = closedCaptionRenderer;
     callback.onRenderers(null, null, renderers);
   }
 

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

@@ -80,9 +80,24 @@ public class HlsChunkSource {
    */
   public static final int ADAPTIVE_MODE_ABRUPT = 3;
 
+  /**
+   * The default target buffer duration in milliseconds.
+   */
+  public static final long DEFAULT_TARGET_BUFFER_DURATION_MS = 40000;
+
+  /**
+   * The default minimum duration of media that needs to be buffered for a switch to a higher
+   * quality variant to be considered.
+   */
+  public static final long DEFAULT_MIN_BUFFER_TO_SWITCH_UP_MS = 5000;
+
+  /**
+   * The default maximum duration of media that needs to be buffered for a switch to a lower
+   * quality variant to be considered.
+   */
+  public static final long DEFAULT_MAX_BUFFER_TO_SWITCH_DOWN_MS = 20000;
+
   private static final float BANDWIDTH_FRACTION = 0.8f;
-  private static final long MIN_BUFFER_TO_SWITCH_UP_US = 5000000;
-  private static final long MAX_BUFFER_TO_SWITCH_DOWN_US = 15000000;
 
   private final SamplePool samplePool = new TsExtractor.SamplePool();
   private final DataSource upstreamDataSource;
@@ -94,6 +109,9 @@ public class HlsChunkSource {
   private final Uri baseUri;
   private final int maxWidth;
   private final int maxHeight;
+  private final long targetBufferDurationUs;
+  private final long minBufferDurationToSwitchUpUs;
+  private final long maxBufferDurationToSwitchDownUs;
 
   /* package */ final HlsMediaPlaylist[] mediaPlaylists;
   /* package */ final long[] lastMediaPlaylistLoadTimesMs;
@@ -106,6 +124,13 @@ public class HlsChunkSource {
   private String encryptedDataSourceIv;
   private byte[] encryptedDataSourceSecretKey;
 
+  public HlsChunkSource(DataSource dataSource, String playlistUrl, HlsPlaylist playlist,
+      BandwidthMeter bandwidthMeter, int[] variantIndices, int adaptiveMode) {
+    this(dataSource, playlistUrl, playlist, bandwidthMeter, variantIndices, adaptiveMode,
+        DEFAULT_TARGET_BUFFER_DURATION_MS, DEFAULT_MIN_BUFFER_TO_SWITCH_UP_MS,
+        DEFAULT_MAX_BUFFER_TO_SWITCH_DOWN_MS);
+  }
+
   /**
    * @param dataSource A {@link DataSource} suitable for loading the media data.
    * @param playlistUrl The playlist URL.
@@ -116,12 +141,24 @@ public class HlsChunkSource {
    * @param adaptiveMode The mode for switching from one variant to another. One of
    *     {@link #ADAPTIVE_MODE_NONE}, {@link #ADAPTIVE_MODE_ABRUPT} and
    *     {@link #ADAPTIVE_MODE_SPLICE}.
+   * @param targetBufferDurationMs The targeted duration of media to buffer ahead of the current
+   *     playback position. Note that the greater this value, the greater the amount of memory
+   *     that will be consumed.
+   * @param minBufferDurationToSwitchUpMs The minimum duration of media that needs to be buffered
+   *     for a switch to a higher quality variant to be considered.
+   * @param maxBufferDurationToSwitchDownMs The maximum duration of media that needs to be buffered
+   *     for a switch to a lower quality variant to be considered.
    */
   public HlsChunkSource(DataSource dataSource, String playlistUrl, HlsPlaylist playlist,
-      BandwidthMeter bandwidthMeter, int[] variantIndices, int adaptiveMode) {
+      BandwidthMeter bandwidthMeter, int[] variantIndices, int adaptiveMode,
+      long targetBufferDurationMs, long minBufferDurationToSwitchUpMs,
+      long maxBufferDurationToSwitchDownMs) {
     this.upstreamDataSource = dataSource;
     this.bandwidthMeter = bandwidthMeter;
     this.adaptiveMode = adaptiveMode;
+    targetBufferDurationUs = targetBufferDurationMs * 1000;
+    minBufferDurationToSwitchUpUs = minBufferDurationToSwitchUpMs * 1000;
+    maxBufferDurationToSwitchDownUs = maxBufferDurationToSwitchDownMs * 1000;
     baseUri = playlist.baseUri;
     bitArray = new BitArray();
     playlistParser = new HlsPlaylistParser();
@@ -182,8 +219,9 @@ public class HlsChunkSource {
    */
   public HlsChunk getChunkOperation(TsChunk previousTsChunk, long seekPositionUs,
       long playbackPositionUs) {
-    if (previousTsChunk != null && previousTsChunk.isLastChunk) {
+    if (previousTsChunk != null && (previousTsChunk.isLastChunk
-      // We're already finished.
+        || previousTsChunk.endTimeUs - playbackPositionUs >= targetBufferDurationUs)) {
+      // We're either finished, or we have the target amount of data buffered.
       return null;
     }
 
@@ -303,8 +341,8 @@ public class HlsChunkSource {
         : adaptiveMode == ADAPTIVE_MODE_SPLICE ? previousTsChunk.startTimeUs
         : previousTsChunk.endTimeUs;
     long bufferedUs = bufferedPositionUs - playbackPositionUs;
-    if ((idealVariantIndex > variantIndex && bufferedUs < MAX_BUFFER_TO_SWITCH_DOWN_US)
+    if ((idealVariantIndex > variantIndex && bufferedUs < maxBufferDurationToSwitchDownUs)
-        || (idealVariantIndex < variantIndex && bufferedUs > MIN_BUFFER_TO_SWITCH_UP_US)) {
+        || (idealVariantIndex < variantIndex && bufferedUs > minBufferDurationToSwitchUpUs)) {
       // Switch variant.
       return idealVariantIndex;
     }

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

@@ -40,7 +40,6 @@ public class HlsSampleSource implements SampleSource, Loader.Callback {
    */
   public static final int DEFAULT_MIN_LOADABLE_RETRY_COUNT = 1;
 
-  private static final long BUFFER_DURATION_US = 20000000;
   private static final int NO_RESET_PENDING = -1;
 
   private final HlsChunkSource chunkSource;
@@ -350,7 +349,7 @@ public class HlsSampleSource implements SampleSource, Loader.Callback {
   }
 
   private void maybeStartLoading() {
-    if (currentLoadableExceptionFatal || loadingFinished) {
+    if (currentLoadableExceptionFatal || loadingFinished || loader.isLoading()) {
       return;
     }
 
@@ -364,17 +363,6 @@ public class HlsSampleSource implements SampleSource, Loader.Callback {
       return;
     }
 
-    boolean bufferFull = false;
-    if (!extractors.isEmpty()) {
-      long largestSampleTimestamp = extractors.getLast().getLargestSampleTimestamp();
-      bufferFull = largestSampleTimestamp != Long.MIN_VALUE
-          && (largestSampleTimestamp - downstreamPositionUs) >= BUFFER_DURATION_US;
-    }
-
-    if (loader.isLoading() || bufferFull) {
-      return;
-    }
-
     HlsChunk nextLoadable = chunkSource.getChunkOperation(previousTsLoadable,
         pendingResetPositionUs, downstreamPositionUs);
     if (nextLoadable == null) {