Add ConcatenatingMediaSource version that fully combines windows.

The published Timeline contains one window only with all periods of
the child sources.

Issue: #4868
PiperOrigin-RevId: 358150276

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

@@ -435,7 +435,13 @@ public abstract class Timeline {
      */
      */
     public long durationUs;
     public long durationUs;
 
 
-    private long positionInWindowUs;
+    /**
+     * The position of the start of this period relative to the start of the window to which it
+     * belongs, in microseconds. May be negative if the start of the period is not within the
+     * window.
+     */
+    public long positionInWindowUs;
+
     private AdPlaybackState adPlaybackState;
     private AdPlaybackState adPlaybackState;
 
 
     /** Creates a new instance with no ad playback state. */
     /** Creates a new instance with no ad playback state. */
@@ -922,13 +928,14 @@ public abstract class Timeline {
       }
       }
     }
     }
     int periodIndex = window.firstPeriodIndex;
     int periodIndex = window.firstPeriodIndex;
-    long periodPositionUs = window.getPositionInFirstPeriodUs() + windowPositionUs;
-    long periodDurationUs = getPeriod(periodIndex, period, /* setIds= */ true).getDurationUs();
-    while (periodDurationUs != C.TIME_UNSET && periodPositionUs >= periodDurationUs
-        && periodIndex < window.lastPeriodIndex) {
-      periodPositionUs -= periodDurationUs;
-      periodDurationUs = getPeriod(++periodIndex, period, /* setIds= */ true).getDurationUs();
-    }
+    getPeriod(periodIndex, period);
+    while (periodIndex < window.lastPeriodIndex
+        && period.positionInWindowUs != windowPositionUs
+        && getPeriod(periodIndex + 1, period).positionInWindowUs <= windowPositionUs) {
+      periodIndex++;
+    }
+    getPeriod(periodIndex, period, /* setIds= */ true);
+    long periodPositionUs = windowPositionUs - period.positionInWindowUs;
     return Pair.create(Assertions.checkNotNull(period.uid), periodPositionUs);
     return Pair.create(Assertions.checkNotNull(period.uid), periodPositionUs);
   }
   }
 
 

library/common/src/main/java/com/google/android/exoplayer2/source/MediaPeriodId.java

@@ -152,6 +152,14 @@ public class MediaPeriodId {
             newPeriodUid, adGroupIndex, adIndexInAdGroup, windowSequenceNumber, nextAdGroupIndex);
             newPeriodUid, adGroupIndex, adIndexInAdGroup, windowSequenceNumber, nextAdGroupIndex);
   }
   }
 
 
+  /** Returns a copy of this period identifier with a new {@code windowSequenceNumber}. */
+  public MediaPeriodId copyWithWindowSequenceNumber(long windowSequenceNumber) {
+    return this.windowSequenceNumber == windowSequenceNumber
+        ? this
+        : new MediaPeriodId(
+            periodUid, adGroupIndex, adIndexInAdGroup, windowSequenceNumber, nextAdGroupIndex);
+  }
+
   /** Returns whether this period identifier identifies an ad in an ad group in a period. */
   /** Returns whether this period identifier identifies an ad in an ad group in a period. */
   public boolean isAd() {
   public boolean isAd() {
     return adGroupIndex != C.INDEX_UNSET;
     return adGroupIndex != C.INDEX_UNSET;

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

@@ -104,9 +104,19 @@ public interface MediaSource {
     }
     }
 
 
     /** See {@link com.google.android.exoplayer2.source.MediaPeriodId#copyWithPeriodUid(Object)}. */
     /** See {@link com.google.android.exoplayer2.source.MediaPeriodId#copyWithPeriodUid(Object)}. */
+    @Override
     public MediaPeriodId copyWithPeriodUid(Object newPeriodUid) {
     public MediaPeriodId copyWithPeriodUid(Object newPeriodUid) {
       return new MediaPeriodId(super.copyWithPeriodUid(newPeriodUid));
       return new MediaPeriodId(super.copyWithPeriodUid(newPeriodUid));
     }
     }
+
+    /**
+     * See {@link
+     * com.google.android.exoplayer2.source.MediaPeriodId#copyWithWindowSequenceNumber(long)}.
+     */
+    @Override
+    public MediaPeriodId copyWithWindowSequenceNumber(long windowSequenceNumber) {
+      return new MediaPeriodId(super.copyWithWindowSequenceNumber(windowSequenceNumber));
+    }
   }
   }
 
 
   /**
   /**