Allow applications to specify the live edge offset.

Also allow use of suggestedPresentationDelay taken from the
manifest, and enable this by default.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130409924

library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java

@@ -57,23 +57,31 @@ public final class DashMediaSource implements MediaSource {
    * The default minimum number of times to retry loading data prior to failing.
    */
   public static final int DEFAULT_MIN_LOADABLE_RETRY_COUNT = 3;
+  /**
+   * A constant indicating that the live edge offset (the offset subtracted from the live edge
+   * when calculating the default position returned by {@link #getDefaultStartPosition(int)}) should
+   * be set to {@link DashManifest#suggestedPresentationDelay} if specified by the manifest, or
+   * {@link #DEFAULT_LIVE_EDGE_OFFSET_FIXED_MS} otherwise.
+   */
+  public static final long DEFAULT_LIVE_EDGE_OFFSET_PREFER_MANIFEST_MS = -1;
+  /**
+   * A fixed default live edge offset (the offset subtracted from the live edge when calculating the
+   * default position returned by {@link #getDefaultStartPosition(int)}).
+   */
+  public static final long DEFAULT_LIVE_EDGE_OFFSET_FIXED_MS = 30000;
   /**
    * The interval in milliseconds between invocations of
    * {@link MediaSource.Listener#onSourceInfoRefreshed(Timeline, Object)} when the source's
    * {@link Window} is changing dynamically (for example, for incomplete live streams).
    */
   private static final int NOTIFY_MANIFEST_INTERVAL_MS = 5000;
-  /**
-   * The offset in milliseconds subtracted from the live edge position when calculating the default
-   * position returned by {@link #getDefaultStartPosition(int)}.
-   */
-  private static final long LIVE_EDGE_OFFSET_MS = 30000;
 
   private static final String TAG = "DashMediaSource";
 
   private final DataSource.Factory manifestDataSourceFactory;
   private final DashChunkSource.Factory chunkSourceFactory;
   private final int minLoadableRetryCount;
+  private final long liveEdgeOffsetMs;
   private final EventDispatcher eventDispatcher;
   private final DashManifestParser manifestParser;
   private final ManifestCallback manifestCallback;
@@ -99,16 +107,18 @@ public final class DashMediaSource implements MediaSource {
       DashChunkSource.Factory chunkSourceFactory, Handler eventHandler,
       AdaptiveMediaSourceEventListener eventListener) {
     this(manifestUri, manifestDataSourceFactory, chunkSourceFactory,
-        DEFAULT_MIN_LOADABLE_RETRY_COUNT, eventHandler, eventListener);
+        DEFAULT_MIN_LOADABLE_RETRY_COUNT, DEFAULT_LIVE_EDGE_OFFSET_PREFER_MANIFEST_MS, eventHandler,
+        eventListener);
   }
 
   public DashMediaSource(Uri manifestUri, DataSource.Factory manifestDataSourceFactory,
-      DashChunkSource.Factory chunkSourceFactory, int minLoadableRetryCount,
+      DashChunkSource.Factory chunkSourceFactory, int minLoadableRetryCount, long liveEdgeOffsetMs,
       Handler eventHandler, AdaptiveMediaSourceEventListener eventListener) {
     this.manifestUri = manifestUri;
     this.manifestDataSourceFactory = manifestDataSourceFactory;
     this.chunkSourceFactory = chunkSourceFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
+    this.liveEdgeOffsetMs = liveEdgeOffsetMs;
     eventDispatcher = new EventDispatcher(eventHandler, eventListener);
     manifestParser = new DashManifestParser(generateContentId());
     manifestCallback = new ManifestCallback();
@@ -159,7 +169,12 @@ public final class DashMediaSource implements MediaSource {
     if (index == 0 && manifest.dynamic) {
       // The stream is live, so return a position a position offset from the live edge.
       int periodIndex = window.endPeriodIndex;
-      long positionMs = window.endTimeMs - LIVE_EDGE_OFFSET_MS;
+      long liveEdgeOffsetForManifest = liveEdgeOffsetMs;
+      if (liveEdgeOffsetForManifest == DEFAULT_LIVE_EDGE_OFFSET_PREFER_MANIFEST_MS) {
+        liveEdgeOffsetForManifest = manifest.suggestedPresentationDelay != -1
+            ? manifest.suggestedPresentationDelay : DEFAULT_LIVE_EDGE_OFFSET_FIXED_MS;
+      }
+      long positionMs = window.endTimeMs - liveEdgeOffsetForManifest;
       while (positionMs < 0 && periodIndex > window.startPeriodIndex) {
         periodIndex--;
         positionMs += manifest.getPeriodDurationMs(periodIndex);

library/src/main/java/com/google/android/exoplayer2/source/dash/manifest/DashManifest.java

@@ -37,6 +37,8 @@ public class DashManifest {
 
   public final long timeShiftBufferDepth;
 
+  public final long suggestedPresentationDelay;
+
   public final UtcTimingElement utcTiming;
 
   public final Uri location;
@@ -44,14 +46,16 @@ public class DashManifest {
   private final List<Period> periods;
 
   public DashManifest(long availabilityStartTime, long duration, long minBufferTime,
-      boolean dynamic, long minUpdatePeriod, long timeShiftBufferDepth, UtcTimingElement utcTiming,
-      Uri location, List<Period> periods) {
+      boolean dynamic, long minUpdatePeriod, long timeShiftBufferDepth,
+      long suggestedPresentationDelay, UtcTimingElement utcTiming, Uri location,
+      List<Period> periods) {
     this.availabilityStartTime = availabilityStartTime;
     this.duration = duration;
     this.minBufferTime = minBufferTime;
     this.dynamic = dynamic;
     this.minUpdatePeriod = minUpdatePeriod;
     this.timeShiftBufferDepth = timeShiftBufferDepth;
+    this.suggestedPresentationDelay = suggestedPresentationDelay;
     this.utcTiming = utcTiming;
     this.location = location;
     this.periods = periods == null ? Collections.<Period>emptyList() : periods;

library/src/main/java/com/google/android/exoplayer2/source/dash/manifest/DashManifestParser.java

@@ -106,8 +106,10 @@ public class DashManifestParser extends DefaultHandler
     long minBufferTimeMs = parseDuration(xpp, "minBufferTime", -1);
     String typeString = xpp.getAttributeValue(null, "type");
     boolean dynamic = typeString != null && typeString.equals("dynamic");
-    long minUpdateTimeMs = (dynamic) ? parseDuration(xpp, "minimumUpdatePeriod", -1) : -1;
-    long timeShiftBufferDepthMs = (dynamic) ? parseDuration(xpp, "timeShiftBufferDepth", -1) : -1;
+    long minUpdateTimeMs = dynamic ? parseDuration(xpp, "minimumUpdatePeriod", -1) : -1;
+    long timeShiftBufferDepthMs = dynamic ? parseDuration(xpp, "timeShiftBufferDepth", -1) : -1;
+    long suggestedPresentationDelayMs = dynamic
+        ? parseDuration(xpp, "suggestedPresentationDelay", -1) : -1;
     UtcTimingElement utcTiming = null;
     Uri location = null;
 
@@ -159,14 +161,17 @@ public class DashManifestParser extends DefaultHandler
     }
 
     return buildMediaPresentationDescription(availabilityStartTime, durationMs, minBufferTimeMs,
-        dynamic, minUpdateTimeMs, timeShiftBufferDepthMs, utcTiming, location, periods);
+        dynamic, minUpdateTimeMs, timeShiftBufferDepthMs, suggestedPresentationDelayMs, utcTiming,
+        location, periods);
   }
 
   protected DashManifest buildMediaPresentationDescription(long availabilityStartTime,
       long durationMs, long minBufferTimeMs, boolean dynamic, long minUpdateTimeMs,
-      long timeShiftBufferDepthMs, UtcTimingElement utcTiming, Uri location, List<Period> periods) {
+      long timeShiftBufferDepthMs, long suggestedPresentationDelayMs, UtcTimingElement utcTiming,
+      Uri location, List<Period> periods) {
     return new DashManifest(availabilityStartTime, durationMs, minBufferTimeMs,
-        dynamic, minUpdateTimeMs, timeShiftBufferDepthMs, utcTiming, location, periods);
+        dynamic, minUpdateTimeMs, timeShiftBufferDepthMs, suggestedPresentationDelayMs, utcTiming,
+        location, periods);
   }
 
   protected UtcTimingElement parseUtcTiming(XmlPullParser xpp) {

playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/gts/DashTest.java

@@ -743,7 +743,8 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
       DefaultDashChunkSource.Factory chunkSourceFactory = new DefaultDashChunkSource.Factory(
           mediaDataSourceFactory);
       return new DashMediaSource(manifestUri, manifestDataSourceFactory, chunkSourceFactory,
-          MIN_LOADABLE_RETRY_COUNT, null, null);
+          MIN_LOADABLE_RETRY_COUNT, DashMediaSource.DEFAULT_LIVE_EDGE_OFFSET_PREFER_MANIFEST_MS,
+          null, null);
     }
 
     @Override