Add server-client time offset to Window.

This offset allows to improve the calculated live offset because it
can take known client-server time offsets into account.

PiperOrigin-RevId: 285970738

extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastTimeline.java

@@ -130,6 +130,7 @@ import java.util.Arrays;
         /* manifest= */ null,
         /* presentationStartTimeMs= */ C.TIME_UNSET,
         /* windowStartTimeMs= */ C.TIME_UNSET,
+        /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
         /* isSeekable= */ !isDynamic,
         isDynamic,
         isLive[windowIndex],

library/core/src/main/java/com/google/android/exoplayer2/BasePlayer.java

@@ -153,7 +153,7 @@ public abstract class BasePlayer implements Player {
     if (windowStartTimeMs == C.TIME_UNSET) {
       return C.TIME_UNSET;
     }
-    return System.currentTimeMillis() - window.windowStartTimeMs - getContentPosition();
+    return window.getCurrentUnixTimeMs() - window.windowStartTimeMs - getContentPosition();
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/Timeline.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2;
 
+import android.os.SystemClock;
 import android.util.Pair;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.source.ads.AdPlaybackState;
@@ -136,19 +137,28 @@ public abstract class Timeline {
 
     /**
      * The start time of the presentation to which this window belongs in milliseconds since the
-     * epoch, or {@link C#TIME_UNSET} if unknown or not applicable. For informational purposes only.
+     * Unix epoch, or {@link C#TIME_UNSET} if unknown or not applicable. For informational purposes
+     * only.
      */
     public long presentationStartTimeMs;
 
     /**
-     * The window's start time in milliseconds since the epoch, or {@link C#TIME_UNSET} if unknown
+     * The window's start time in milliseconds since the Unix epoch, or {@link C#TIME_UNSET} if
-     * or not applicable. For informational purposes only.
+     * unknown or not applicable. For informational purposes only.
      */
     public long windowStartTimeMs;
 
     /**
-     * Whether it's possible to seek within this window.
+     * The offset between {@link SystemClock#elapsedRealtime()} and the time since the Unix epoch
+     * according to the clock of the media origin server, or {@link C#TIME_UNSET} if unknown or not
+     * applicable.
+     *
+     * <p>Note that the current Unix time can be retrieved using {@link #getCurrentUnixTimeMs()} and
+     * is calculated as {@code SystemClock.elapsedRealtime() + elapsedRealtimeEpochOffsetMs}.
      */
+    public long elapsedRealtimeEpochOffsetMs;
+
+    /** Whether it's possible to seek within this window. */
     public boolean isSeekable;
 
     // TODO: Split this to better describe which parts of the window might change. For example it
@@ -205,6 +215,7 @@ public abstract class Timeline {
         @Nullable Object manifest,
         long presentationStartTimeMs,
         long windowStartTimeMs,
+        long elapsedRealtimeEpochOffsetMs,
         boolean isSeekable,
         boolean isDynamic,
         boolean isLive,
@@ -218,6 +229,7 @@ public abstract class Timeline {
       this.manifest = manifest;
       this.presentationStartTimeMs = presentationStartTimeMs;
       this.windowStartTimeMs = windowStartTimeMs;
+      this.elapsedRealtimeEpochOffsetMs = elapsedRealtimeEpochOffsetMs;
       this.isSeekable = isSeekable;
       this.isDynamic = isDynamic;
       this.isLive = isLive;
@@ -279,6 +291,16 @@ public abstract class Timeline {
       return positionInFirstPeriodUs;
     }
 
+    /**
+     * Returns the current time in milliseconds since the Unix epoch.
+     *
+     * <p>This method applies {@link #elapsedRealtimeEpochOffsetMs known corrections} made available
+     * by the media such that this time corresponds to the clock of the media origin server.
+     */
+    public long getCurrentUnixTimeMs() {
+      return Util.getNowUnixTimeMs(elapsedRealtimeEpochOffsetMs);
+    }
+
     @Override
     public boolean equals(@Nullable Object obj) {
       if (this == obj) {
@@ -293,6 +315,7 @@ public abstract class Timeline {
           && Util.areEqual(manifest, that.manifest)
           && presentationStartTimeMs == that.presentationStartTimeMs
           && windowStartTimeMs == that.windowStartTimeMs
+          && elapsedRealtimeEpochOffsetMs == that.elapsedRealtimeEpochOffsetMs
           && isSeekable == that.isSeekable
           && isDynamic == that.isDynamic
           && isLive == that.isLive
@@ -311,6 +334,9 @@ public abstract class Timeline {
       result = 31 * result + (manifest == null ? 0 : manifest.hashCode());
       result = 31 * result + (int) (presentationStartTimeMs ^ (presentationStartTimeMs >>> 32));
       result = 31 * result + (int) (windowStartTimeMs ^ (windowStartTimeMs >>> 32));
+      result =
+          31 * result
+              + (int) (elapsedRealtimeEpochOffsetMs ^ (elapsedRealtimeEpochOffsetMs >>> 32));
       result = 31 * result + (isSeekable ? 1 : 0);
       result = 31 * result + (isDynamic ? 1 : 0);
       result = 31 * result + (isLive ? 1 : 0);

library/core/src/main/java/com/google/android/exoplayer2/source/MaskingMediaSource.java

@@ -337,6 +337,7 @@ public final class MaskingMediaSource extends CompositeMediaSource<Void> {
           /* manifest= */ null,
           /* presentationStartTimeMs= */ C.TIME_UNSET,
           /* windowStartTimeMs= */ C.TIME_UNSET,
+          /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
           /* isSeekable= */ false,
           // Dynamic window to indicate pending timeline updates.
           /* isDynamic= */ true,

library/core/src/main/java/com/google/android/exoplayer2/source/SinglePeriodTimeline.java

@@ -29,6 +29,7 @@ public final class SinglePeriodTimeline extends Timeline {
 
   private final long presentationStartTimeMs;
   private final long windowStartTimeMs;
+  private final long elapsedRealtimeEpochOffsetMs;
   private final long periodDurationUs;
   private final long windowDurationUs;
   private final long windowPositionInPeriodUs;
@@ -110,6 +111,7 @@ public final class SinglePeriodTimeline extends Timeline {
     this(
         /* presentationStartTimeMs= */ C.TIME_UNSET,
         /* windowStartTimeMs= */ C.TIME_UNSET,
+        /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
         periodDurationUs,
         windowDurationUs,
         windowPositionInPeriodUs,
@@ -126,8 +128,12 @@ public final class SinglePeriodTimeline extends Timeline {
    * position in the period.
    *
    * @param presentationStartTimeMs The start time of the presentation in milliseconds since the
-   *     epoch.
+   *     epoch, or {@link C#TIME_UNSET} if unknown or not applicable.
-   * @param windowStartTimeMs The window's start time in milliseconds since the epoch.
+   * @param windowStartTimeMs The window's start time in milliseconds since the epoch, or {@link
+   *     C#TIME_UNSET} if unknown or not applicable.
+   * @param elapsedRealtimeEpochOffsetMs The offset between {@link
+   *     android.os.SystemClock#elapsedRealtime()} and the time since the Unix epoch according to
+   *     the clock of the media origin server, or {@link C#TIME_UNSET} if unknown or not applicable.
    * @param periodDurationUs The duration of the period in microseconds.
    * @param windowDurationUs The duration of the window in microseconds.
    * @param windowPositionInPeriodUs The position of the start of the window in the period, in
@@ -143,6 +149,7 @@ public final class SinglePeriodTimeline extends Timeline {
   public SinglePeriodTimeline(
       long presentationStartTimeMs,
       long windowStartTimeMs,
+      long elapsedRealtimeEpochOffsetMs,
       long periodDurationUs,
       long windowDurationUs,
       long windowPositionInPeriodUs,
@@ -154,6 +161,7 @@ public final class SinglePeriodTimeline extends Timeline {
       @Nullable Object tag) {
     this.presentationStartTimeMs = presentationStartTimeMs;
     this.windowStartTimeMs = windowStartTimeMs;
+    this.elapsedRealtimeEpochOffsetMs = elapsedRealtimeEpochOffsetMs;
     this.periodDurationUs = periodDurationUs;
     this.windowDurationUs = windowDurationUs;
     this.windowPositionInPeriodUs = windowPositionInPeriodUs;
@@ -192,13 +200,14 @@ public final class SinglePeriodTimeline extends Timeline {
         manifest,
         presentationStartTimeMs,
         windowStartTimeMs,
+        elapsedRealtimeEpochOffsetMs,
         isSeekable,
         isDynamic,
         isLive,
         windowDefaultStartPositionUs,
         windowDurationUs,
-        0,
+        /* firstPeriodIndex= */ 0,
-        0,
+        /* lastPeriodIndex= */ 0,
         windowPositionInPeriodUs);
   }
 

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -39,6 +39,7 @@ import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Parcel;
+import android.os.SystemClock;
 import android.security.NetworkSecurityPolicy;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
@@ -2045,6 +2046,19 @@ public final class Util {
     }
   }
 
+  /**
+   * Returns the current time in milliseconds since the epoch.
+   *
+   * @param elapsedRealtimeEpochOffsetMs The offset between {@link SystemClock#elapsedRealtime()}
+   *     and the time since the Unix epoch, or {@link C#TIME_UNSET} if unknown.
+   * @return The Unix time in milliseconds since the epoch.
+   */
+  public static long getNowUnixTimeMs(long elapsedRealtimeEpochOffsetMs) {
+    return elapsedRealtimeEpochOffsetMs == C.TIME_UNSET
+        ? System.currentTimeMillis()
+        : SystemClock.elapsedRealtime() + elapsedRealtimeEpochOffsetMs;
+  }
+
   @Nullable
   private static String getSystemProperty(String name) {
     try {

library/core/src/test/java/com/google/android/exoplayer2/TimelineTest.java

@@ -134,6 +134,7 @@ public class TimelineTest {
             window.manifest,
             window.presentationStartTimeMs,
             window.windowStartTimeMs,
+            window.elapsedRealtimeEpochOffsetMs,
             window.isSeekable,
             window.isDynamic,
             window.isLive,

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

@@ -42,7 +42,8 @@ public interface DashChunkSource extends ChunkSource {
      * @param trackSelection The track selection.
      * @param elapsedRealtimeOffsetMs If known, an estimate of the instantaneous difference between
      *     server-side unix time and {@link SystemClock#elapsedRealtime()} in milliseconds,
-     *     specified as the server's unix time minus the local elapsed time. If unknown, set to 0.
+     *     specified as the server's unix time minus the local elapsed time. Or {@link
+     *     com.google.android.exoplayer2.C#TIME_UNSET} if unknown.
      * @param enableEventMessageTrack Whether to output an event message track.
      * @param closedCaptionFormats The {@link Format Formats} of closed caption tracks to be output.
      * @param transferListener The transfer listener which should be informed of any data transfers.

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

@@ -621,6 +621,7 @@ public final class DashMediaSource extends BaseMediaSource {
     periodsById = new SparseArray<>();
     playerEmsgCallback = new DefaultPlayerEmsgCallback();
     expiredManifestPublishTimeUs = C.TIME_UNSET;
+    elapsedRealtimeOffsetMs = C.TIME_UNSET;
     if (sideloadedManifest) {
       Assertions.checkState(!manifest.dynamic);
       manifestCallback = null;
@@ -723,7 +724,7 @@ public final class DashMediaSource extends BaseMediaSource {
       handler.removeCallbacksAndMessages(null);
       handler = null;
     }
-    elapsedRealtimeOffsetMs = 0;
+    elapsedRealtimeOffsetMs = C.TIME_UNSET;
     staleManifestReloadAttempt = 0;
     expiredManifestPublishTimeUs = C.TIME_UNSET;
     firstPeriodId = 0;
@@ -969,7 +970,8 @@ public final class DashMediaSource extends BaseMediaSource {
     if (manifest.dynamic && !lastPeriodSeekInfo.isIndexExplicit) {
       // The manifest describes an incomplete live stream. Update the start/end times to reflect the
       // live stream duration and the manifest's time shift buffer depth.
-      long liveStreamDurationUs = getNowUnixTimeUs() - C.msToUs(manifest.availabilityStartTimeMs);
+      long nowUnixTimeUs = C.msToUs(Util.getNowUnixTimeMs(elapsedRealtimeOffsetMs));
+      long liveStreamDurationUs = nowUnixTimeUs - C.msToUs(manifest.availabilityStartTimeMs);
       long liveStreamEndPositionInLastPeriodUs = liveStreamDurationUs
           - C.msToUs(manifest.getPeriod(lastPeriodIndex).startMs);
       currentEndTimeUs = Math.min(liveStreamEndPositionInLastPeriodUs, currentEndTimeUs);
@@ -1022,6 +1024,7 @@ public final class DashMediaSource extends BaseMediaSource {
         new DashTimeline(
             manifest.availabilityStartTimeMs,
             windowStartTimeMs,
+            elapsedRealtimeOffsetMs,
             firstPeriodId,
             currentStartTimeUs,
             windowDurationUs,
@@ -1093,14 +1096,6 @@ public final class DashMediaSource extends BaseMediaSource {
     manifestEventDispatcher.loadStarted(loadable.dataSpec, loadable.type, elapsedRealtimeMs);
   }
 
-  private long getNowUnixTimeUs() {
-    if (elapsedRealtimeOffsetMs != 0) {
-      return C.msToUs(SystemClock.elapsedRealtime() + elapsedRealtimeOffsetMs);
-    } else {
-      return C.msToUs(System.currentTimeMillis());
-    }
-  }
-
   private static final class PeriodSeekInfo {
 
     public static PeriodSeekInfo createPeriodSeekInfo(
@@ -1170,6 +1165,7 @@ public final class DashMediaSource extends BaseMediaSource {
 
     private final long presentationStartTimeMs;
     private final long windowStartTimeMs;
+    private final long elapsedRealtimeEpochOffsetMs;
 
     private final int firstPeriodId;
     private final long offsetInFirstPeriodUs;
@@ -1181,6 +1177,7 @@ public final class DashMediaSource extends BaseMediaSource {
     public DashTimeline(
         long presentationStartTimeMs,
         long windowStartTimeMs,
+        long elapsedRealtimeEpochOffsetMs,
         int firstPeriodId,
         long offsetInFirstPeriodUs,
         long windowDurationUs,
@@ -1189,6 +1186,7 @@ public final class DashMediaSource extends BaseMediaSource {
         @Nullable Object windowTag) {
       this.presentationStartTimeMs = presentationStartTimeMs;
       this.windowStartTimeMs = windowStartTimeMs;
+      this.elapsedRealtimeEpochOffsetMs = elapsedRealtimeEpochOffsetMs;
       this.firstPeriodId = firstPeriodId;
       this.offsetInFirstPeriodUs = offsetInFirstPeriodUs;
       this.windowDurationUs = windowDurationUs;
@@ -1228,6 +1226,7 @@ public final class DashMediaSource extends BaseMediaSource {
           manifest,
           presentationStartTimeMs,
           windowStartTimeMs,
+          elapsedRealtimeEpochOffsetMs,
           /* isSeekable= */ true,
           /* isDynamic= */ isMovingLiveWindow(manifest),
           /* isLive= */ manifest.dynamic,

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

@@ -136,7 +136,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
    * @param dataSource A {@link DataSource} suitable for loading the media data.
    * @param elapsedRealtimeOffsetMs If known, an estimate of the instantaneous difference between
    *     server-side unix time and {@link SystemClock#elapsedRealtime()} in milliseconds, specified
-   *     as the server's unix time minus the local elapsed time. If unknown, set to 0.
+   *     as the server's unix time minus the local elapsed time. Or {@link C#TIME_UNSET} if unknown.
    * @param maxSegmentsPerLoad The maximum number of segments to combine into a single request. Note
    *     that segments will only be combined if their {@link Uri}s are the same and if their data
    *     ranges are adjacent.
@@ -267,7 +267,7 @@ public class DefaultDashChunkSource implements DashChunkSource {
       return;
     }
 
-    long nowUnixTimeUs = getNowUnixTimeUs();
+    long nowUnixTimeUs = C.msToUs(Util.getNowUnixTimeMs(elapsedRealtimeOffsetMs));
     MediaChunk previous = queue.isEmpty() ? null : queue.get(queue.size() - 1);
     MediaChunkIterator[] chunkIterators = new MediaChunkIterator[trackSelection.length()];
     for (int i = 0; i < chunkIterators.length; i++) {
@@ -474,14 +474,6 @@ public class DefaultDashChunkSource implements DashChunkSource {
         ? representationHolder.getSegmentEndTimeUs(lastAvailableSegmentNum) : C.TIME_UNSET;
   }
 
-  private long getNowUnixTimeUs() {
-    if (elapsedRealtimeOffsetMs != 0) {
-      return (SystemClock.elapsedRealtime() + elapsedRealtimeOffsetMs) * 1000;
-    } else {
-      return System.currentTimeMillis() * 1000;
-    }
-  }
-
   private long resolveTimeToLiveEdgeUs(long playbackPositionUs) {
     boolean resolveTimeToLiveEdgePossible = manifest.dynamic && liveEdgeTimeUs != C.TIME_UNSET;
     return resolveTimeToLiveEdgePossible ? liveEdgeTimeUs - playbackPositionUs : C.TIME_UNSET;

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

@@ -468,6 +468,7 @@ public final class HlsMediaSource extends BaseMediaSource
           new SinglePeriodTimeline(
               presentationStartTimeMs,
               windowStartTimeMs,
+              /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
               periodDurationUs,
               /* windowDurationUs= */ playlist.durationUs,
               /* windowPositionInPeriodUs= */ offsetFromInitialStartTimeUs,
@@ -485,6 +486,7 @@ public final class HlsMediaSource extends BaseMediaSource
           new SinglePeriodTimeline(
               presentationStartTimeMs,
               windowStartTimeMs,
+              /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
               /* periodDurationUs= */ playlist.durationUs,
               /* windowDurationUs= */ playlist.durationUs,
               /* windowPositionInPeriodUs= */ 0,

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeTimeline.java

@@ -219,6 +219,7 @@ public final class FakeTimeline extends Timeline {
         manifests[windowIndex],
         /* presentationStartTimeMs= */ C.TIME_UNSET,
         /* windowStartTimeMs= */ C.TIME_UNSET,
+        /* elapsedRealtimeEpochOffsetMs= */ C.TIME_UNSET,
         windowDefinition.isSeekable,
         windowDefinition.isDynamic,
         windowDefinition.isLive,