Introduce HlsTrackSelector.

This is equivalent to DashTrackSelector and SmoothStreamingTrackSelector.
This is a step toward allowing HlsChunkSource to expose multiple tracks,
which is a requirement for supporting WebVtt.

This change also enables WebVtt extractor instantiation.

Issue: #151
Issue: #676
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=111698833

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

@@ -19,14 +19,12 @@ import com.google.android.exoplayer.DefaultLoadControl;
 import com.google.android.exoplayer.LoadControl;
 import com.google.android.exoplayer.MediaCodecAudioTrackRenderer;
 import com.google.android.exoplayer.MediaCodecSelector;
-import com.google.android.exoplayer.MediaCodecUtil.DecoderQueryException;
 import com.google.android.exoplayer.MediaCodecVideoTrackRenderer;
 import com.google.android.exoplayer.TrackRenderer;
 import com.google.android.exoplayer.audio.AudioCapabilities;
-import com.google.android.exoplayer.chunk.VideoFormatSelectorUtil;
 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;
@@ -130,25 +128,10 @@ public class HlsRendererBuilder implements RendererBuilder {
       LoadControl loadControl = new DefaultLoadControl(new DefaultAllocator(BUFFER_SEGMENT_SIZE));
       DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
 
-      int[] variantIndices = null;
-      if (manifest instanceof HlsMasterPlaylist) {
-        HlsMasterPlaylist masterPlaylist = (HlsMasterPlaylist) manifest;
-        try {
-          variantIndices = VideoFormatSelectorUtil.selectVideoFormatsForDefaultDisplay(
-              context, masterPlaylist.variants, null, false);
-        } catch (DecoderQueryException e) {
-          player.onRenderersError(e);
-          return;
-        }
-        if (variantIndices.length == 0) {
-          player.onRenderersError(new IllegalStateException("No variants selected."));
-          return;
-        }
-      }
-
       DataSource dataSource = new DefaultUriDataSource(context, bandwidthMeter, userAgent);
-      HlsChunkSource chunkSource = new HlsChunkSource(dataSource, url, manifest, bandwidthMeter,
-          new PtsTimestampAdjusterProvider(), variantIndices, HlsChunkSource.ADAPTIVE_MODE_SPLICE);
+      HlsChunkSource chunkSource = new HlsChunkSource(dataSource, url, manifest,
+          DefaultHlsTrackSelector.newDefaultInstance(context), bandwidthMeter,
+          new PtsTimestampAdjusterProvider(), HlsChunkSource.ADAPTIVE_MODE_SPLICE);
       HlsSampleSource sampleSource = new HlsSampleSource(chunkSource, loadControl,
           BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, mainHandler, player, DemoPlayer.TYPE_VIDEO);
       MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(context,

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

+/*
+ * Copyright (C) 2014 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.exoplayer.hls;
+
+import com.google.android.exoplayer.chunk.VideoFormatSelectorUtil;
+
+import android.content.Context;
+import android.text.TextUtils;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A default {@link HlsTrackSelector} implementation.
+ */
+public final class DefaultHlsTrackSelector implements HlsTrackSelector {
+
+  private static final int TYPE_DEFAULT = 0;
+  private static final int TYPE_VTT = 1;
+
+  private final Context context;
+  private final int type;
+
+  /**
+   * Creates a {@link DefaultHlsTrackSelector} that selects the streams defined in the playlist.
+   *
+   * @param context A context.
+   * @return The selector instance.
+   */
+  public static DefaultHlsTrackSelector newDefaultInstance(Context context) {
+    return new DefaultHlsTrackSelector(context, TYPE_DEFAULT);
+  }
+
+  /**
+   * Creates a {@link DefaultHlsTrackSelector} that selects subtitle renditions.
+   *
+   * @return The selector instance.
+   */
+  public static DefaultHlsTrackSelector newVttInstance() {
+    return new DefaultHlsTrackSelector(null, TYPE_VTT);
+  }
+
+  private DefaultHlsTrackSelector(Context context, int type) {
+    this.context = context;
+    this.type = type;
+  }
+
+  @Override
+  public void selectTracks(HlsMasterPlaylist playlist, Output output) throws IOException {
+    if (type == TYPE_VTT) {
+      List<Variant> subtitleVariants = playlist.subtitles;
+      if (subtitleVariants != null && !subtitleVariants.isEmpty()) {
+        for (int i = 0; i < subtitleVariants.size(); i++) {
+          output.fixedTrack(playlist, subtitleVariants.get(i));
+        }
+      }
+      return;
+    }
+
+    // Type is TYPE_DEFAULT.
+
+    ArrayList<Variant> enabledVariantList = new ArrayList<>();
+    int[] variantIndices = VideoFormatSelectorUtil.selectVideoFormatsForDefaultDisplay(
+        context, playlist.variants, null, false);
+    for (int i = 0; i < variantIndices.length; i++) {
+      enabledVariantList.add(playlist.variants.get(variantIndices[i]));
+    }
+
+    ArrayList<Variant> definiteVideoVariants = new ArrayList<>();
+    ArrayList<Variant> definiteAudioOnlyVariants = new ArrayList<>();
+    for (int i = 0; i < enabledVariantList.size(); i++) {
+      Variant variant = enabledVariantList.get(i);
+      if (variant.format.height > 0 || variantHasExplicitCodecWithPrefix(variant, "avc")) {
+        definiteVideoVariants.add(variant);
+      } else if (variantHasExplicitCodecWithPrefix(variant, "mp4a")) {
+        definiteAudioOnlyVariants.add(variant);
+      }
+    }
+
+    if (!definiteVideoVariants.isEmpty()) {
+      // We've identified some variants as definitely containing video. Assume variants within the
+      // master playlist are marked consistently, and hence that we have the full set. Filter out
+      // any other variants, which are likely to be audio only.
+      enabledVariantList = definiteVideoVariants;
+    } else if (definiteAudioOnlyVariants.size() < enabledVariantList.size()) {
+      // We've identified some variants, but not all, as being audio only. Filter them out to leave
+      // the remaining variants, which are likely to contain video.
+      enabledVariantList.removeAll(definiteAudioOnlyVariants);
+    } else {
+      // Leave the enabled variants unchanged. They're likely either all video or all audio.
+    }
+
+    if (enabledVariantList.size() > 1) {
+      Variant[] enabledVariants = new Variant[enabledVariantList.size()];
+      enabledVariantList.toArray(enabledVariants);
+      output.adaptiveTrack(playlist, enabledVariants);
+    }
+    for (int i = 0; i < enabledVariantList.size(); i++) {
+      output.fixedTrack(playlist, enabledVariantList.get(i));
+    }
+  }
+
+  private static boolean variantHasExplicitCodecWithPrefix(Variant variant, String prefix) {
+    String codecs = variant.format.codecs;
+    if (TextUtils.isEmpty(codecs)) {
+      return false;
+    }
+    String[] codecArray = codecs.split("(\\s*,\\s*)|(\\s*$)");
+    for (int i = 0; i < codecArray.length; i++) {
+      if (codecArray[i].startsWith(prefix)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+}

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

@@ -129,6 +129,8 @@ public final class HlsSampleSource implements SampleSource, SampleSourceReader,
   public boolean prepare(long positionUs) {
     if (prepared) {
       return true;
+    } else if (!chunkSource.prepare()) {
+      return false;
     }
     if (!extractors.isEmpty()) {
       while (true) {

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

+/*
+ * Copyright (C) 2014 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.exoplayer.hls;
+
+import java.io.IOException;
+
+/**
+ * Specifies a track selection from an {@link HlsMasterPlaylist}.
+ */
+public interface HlsTrackSelector {
+
+  /**
+   * Defines a selector output.
+   */
+  interface Output {
+
+    /**
+     * Outputs an adaptive track, covering the specified representations in the specified
+     * adaptation set.
+     *
+     * @param playlist The master playlist being processed.
+     * @param variants The variants to use for the adaptive track.
+     */
+    void adaptiveTrack(HlsMasterPlaylist playlist, Variant[] variants);
+
+    /**
+     * Outputs an fixed track corresponding to the specified representation in the specified
+     * adaptation set.
+     *
+     * @param playlist The master playlist being processed.
+     * @param variant The variant to use for the track.
+     */
+    void fixedTrack(HlsMasterPlaylist playlist, Variant variant);
+
+  }
+
+  /**
+   * Outputs a track selection for a given period.
+   *
+   * @param playlist The master playlist to process.
+   * @param output The output to receive tracks.
+   * @throws IOException If an error occurs processing the period.
+   */
+  void selectTracks(HlsMasterPlaylist playlist, Output output) throws IOException;
+
+}