Fix crash when the live default position moves past a playing SSAI ad

RELEASENOTES.md

@@ -32,6 +32,9 @@
     *   Fix an issue where Player.getCurrentPosition() could return stale values
         (updating only a few times per second) when dynamic scheduling is
         enabled ([#3286](https://github.com/androidx/media/issues/3286)).
+    *   Fix `ArrayIndexOutOfBoundsException` when a live timeline refresh moves
+        the default position past a server-side inserted ad that is currently
+        being played ([#3348](https://github.com/androidx/media/issues/3348)).
 *   CompositionPlayer:
     *   Support configuring the frame rate of video frame aggregation via
         `Composition.Builder.setVideoFrameAggregationParameters` for playback

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ExoPlayerImplInternal.java

@@ -4103,7 +4103,7 @@ private static PositionUpdateForPlaylistChange resolvePositionForPlaylistChange(
             oldPeriodId,
             oldContentPositionUs,
             periodIdWithAds,
-            timeline.getPeriodByUid(newPeriodUid, period),
+            timeline.getPeriodByUid(periodIdWithAds.periodUid, period),
             newContentPositionUs);
     MediaPeriodId newPeriodId =
         onlyNextAdGroupIndexIncreased || isInStreamAdChange ? oldPeriodId : periodIdWithAds;

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/ExoPlayerAdTest.java

@@ -1058,6 +1058,66 @@ public void adInMovingLiveWindow_keepsContentPosition() throws Exception {
     assertThat(contentPositionAfterLiveWindowUpdateMs).isEqualTo(2000);
   }
 
+  @Test
+  public void timelineRefresh_movingLiveDefaultPositionPastPlayingSsaiAd_keepsPlayingAd()
+      throws Exception {
+    // Live window with three 20s periods: |- p0 content -|- p1 ad -|- p2 content -|.
+    Object adsId = new Object();
+    TimelineWindowDefinition liveWindowDefinition =
+        new TimelineWindowDefinition.Builder()
+            .setDynamic(true)
+            .setLive(true)
+            .setSeekable(true)
+            .setPeriodCount(3)
+            .setDurationUs(60_000_000)
+            .setWindowStartTimeUs(1_720_000_000_000_000L)
+            .setWindowPositionInFirstPeriodUs(0)
+            .setDefaultPositionUs(30_000_000)
+            .build();
+    Timeline initialContentTimeline = new FakeTimeline(liveWindowDefinition);
+    // p1 is entirely covered by a server-side inserted ad.
+    AdPlaybackState contentOnlyAdPlaybackState = new AdPlaybackState(adsId);
+    AdPlaybackState adPeriodAdPlaybackState =
+        addAdGroupToAdPlaybackState(
+            contentOnlyAdPlaybackState,
+            /* fromPositionUs= */ 0,
+            /* contentResumeOffsetUs= */ 20_000_000,
+            /* adDurationsUs...= */ 20_000_000);
+    // ServerSideAdInsertionMediaSource requires an AdPlaybackState for every period.
+    ImmutableMap<Object, AdPlaybackState> adPlaybackStates =
+        ImmutableMap.of(
+            initialContentTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+            contentOnlyAdPlaybackState,
+            initialContentTimeline.getUidOfPeriod(/* periodIndex= */ 1),
+            adPeriodAdPlaybackState,
+            initialContentTimeline.getUidOfPeriod(/* periodIndex= */ 2),
+            contentOnlyAdPlaybackState);
+    FakeMediaSource contentMediaSource = new FakeMediaSource(initialContentTimeline);
+    ServerSideAdInsertionMediaSource mediaSource =
+        new ServerSideAdInsertionMediaSource(
+            contentMediaSource, /* adPlaybackStateUpdater= */ contentTimeline -> false);
+    mediaSource.setAdPlaybackStates(adPlaybackStates, initialContentTimeline);
+    ExoPlayer player = parameterizeTestExoPlayerBuilder(new TestExoPlayerBuilder(context)).build();
+
+    // Join the live stream while the ad in p1 is on air.
+    player.setMediaSource(mediaSource);
+    player.prepare();
+    advance(player).untilState(Player.STATE_READY);
+    boolean isPlayingAdAfterJoining = player.isPlayingAd();
+    // Refresh the live timeline with a default position that moved past the ad, into p2.
+    contentMediaSource.setNewSourceInfo(
+        new FakeTimeline(
+            liveWindowDefinition.buildUpon().setDefaultPositionUs(45_000_000).build()));
+    advance(player).untilPendingCommandsAreFullyHandled();
+    boolean isPlayingAdAfterRefresh = player.isPlayingAd();
+    @Nullable PlaybackException error = player.getPlayerError();
+    player.release();
+
+    assertThat(isPlayingAdAfterJoining).isTrue();
+    assertThat(error).isNull();
+    assertThat(isPlayingAdAfterRefresh).isTrue();
+  }
+
   @Test
   public void addMediaSource_whilePlayingAd_correctMasking() throws Exception {
     long contentDurationMs = 10_000;