diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 7fb10727cc..28d7fb5597 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -16,8 +16,12 @@
   ([#5351](https://github.com/google/ExoPlayer/issues/5351)).
 * Fix issue where uneven track durations in MP4 streams can cause OOM problems
   ([#3670](https://github.com/google/ExoPlayer/issues/3670)).
-* Add the sub text to the MediaDescriptionAdapter of the
-  PlayerNotificationManager.
+* Add `startPositionUs` to `MediaSource.createPeriod`. This fixes an issue where
+  using lazy preparation in `ConcatenatingMediaSource` with an
+  `ExtractorMediaSource` overrides initial seek positions
+  ([#5350](https://github.com/google/ExoPlayer/issues/5350)).
+* Add subtext to the `MediaDescriptionAdapter` of the
+  `PlayerNotificationManager`.
 
 ### 2.9.3 ###
 
diff --git a/extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsMediaSource.java b/extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsMediaSource.java
index 85042c4354..0978ee401c 100644
--- a/extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsMediaSource.java
+++ b/extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsMediaSource.java
@@ -97,8 +97,8 @@ public final class ImaAdsMediaSource extends BaseMediaSource implements SourceIn
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
-    return adsMediaSource.createPeriod(id, allocator);
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
+    return adsMediaSource.createPeriod(id, allocator, startPositionUs);
   }
 
   @Override
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/MediaPeriodHolder.java b/library/core/src/main/java/com/google/android/exoplayer2/MediaPeriodHolder.java
index 5925c8f383..8e51740c56 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/MediaPeriodHolder.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/MediaPeriodHolder.java
@@ -79,7 +79,7 @@ import com.google.android.exoplayer2.util.Log;
     this.info = info;
     sampleStreams = new SampleStream[rendererCapabilities.length];
     mayRetainStreamFlags = new boolean[rendererCapabilities.length];
-    MediaPeriod mediaPeriod = mediaSource.createPeriod(info.id, allocator);
+    MediaPeriod mediaPeriod = mediaSource.createPeriod(info.id, allocator, info.startPositionUs);
     if (info.id.endPositionUs != C.TIME_END_OF_SOURCE) {
       mediaPeriod =
           new ClippingMediaPeriod(
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaSource.java
index 3ed18049bf..fce1c4b877 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaSource.java
@@ -240,10 +240,10 @@ public final class ClippingMediaSource extends CompositeMediaSource<Void> {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     ClippingMediaPeriod mediaPeriod =
         new ClippingMediaPeriod(
-            mediaSource.createPeriod(id, allocator),
+            mediaSource.createPeriod(id, allocator, startPositionUs),
             enableInitialDiscontinuity,
             periodStartUs,
             periodEndUs);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java
index 72ecd2c767..c93afdb249 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java
@@ -476,7 +476,8 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
   }
 
   @Override
-  public final MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public final MediaPeriod createPeriod(
+      MediaPeriodId id, Allocator allocator, long startPositionUs) {
     Object mediaSourceHolderUid = getMediaSourceHolderUid(id.periodUid);
     MediaSourceHolder holder = mediaSourceByUid.get(mediaSourceHolderUid);
     if (holder == null) {
@@ -484,7 +485,8 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
       holder = new MediaSourceHolder(new DummyMediaSource());
       holder.hasStartedPreparing = true;
     }
-    DeferredMediaPeriod mediaPeriod = new DeferredMediaPeriod(holder.mediaSource, id, allocator);
+    DeferredMediaPeriod mediaPeriod =
+        new DeferredMediaPeriod(holder.mediaSource, id, allocator, startPositionUs);
     mediaSourceByMediaPeriod.put(mediaPeriod, holder);
     holder.activeMediaPeriods.add(mediaPeriod);
     if (!holder.hasStartedPreparing) {
@@ -1093,7 +1095,7 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
     }
 
     @Override
-    public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+    public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
       throw new UnsupportedOperationException();
     }
 
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java b/library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java
index 26c25a749e..858769180d 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java
@@ -25,7 +25,7 @@ import java.io.IOException;
 
 /**
  * Media period that wraps a media source and defers calling its {@link
- * MediaSource#createPeriod(MediaPeriodId, Allocator)} method until {@link
+ * MediaSource#createPeriod(MediaPeriodId, Allocator, long)} method until {@link
  * #createPeriod(MediaPeriodId)} has been called. This is useful if you need to return a media
  * period immediately but the media source that should create it is not yet prepared.
  */
@@ -60,11 +60,14 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
    * @param mediaSource The media source to wrap.
    * @param id The identifier used to create the deferred media period.
    * @param allocator The allocator used to create the media period.
+   * @param preparePositionUs The expected start position, in microseconds.
    */
-  public DeferredMediaPeriod(MediaSource mediaSource, MediaPeriodId id, Allocator allocator) {
+  public DeferredMediaPeriod(
+      MediaSource mediaSource, MediaPeriodId id, Allocator allocator, long preparePositionUs) {
     this.id = id;
     this.allocator = allocator;
     this.mediaSource = mediaSource;
+    this.preparePositionUs = preparePositionUs;
     preparePositionOverrideUs = C.TIME_UNSET;
   }
 
@@ -86,28 +89,25 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   /**
    * Overrides the default prepare position at which to prepare the media period. This value is only
-   * used if the call to {@link MediaPeriod#prepare(Callback, long)} is being deferred.
+   * used if called before {@link #createPeriod(MediaPeriodId)}.
    *
-   * @param defaultPreparePositionUs The default prepare position to use, in microseconds.
+   * @param preparePositionUs The default prepare position to use, in microseconds.
    */
-  public void overridePreparePositionUs(long defaultPreparePositionUs) {
-    preparePositionOverrideUs = defaultPreparePositionUs;
+  public void overridePreparePositionUs(long preparePositionUs) {
+    preparePositionOverrideUs = preparePositionUs;
   }
 
   /**
-   * Calls {@link MediaSource#createPeriod(MediaPeriodId, Allocator)} on the wrapped source then
-   * prepares it if {@link #prepare(Callback, long)} has been called. Call {@link #releasePeriod()}
-   * to release the period.
+   * Calls {@link MediaSource#createPeriod(MediaPeriodId, Allocator, long)} on the wrapped source
+   * then prepares it if {@link #prepare(Callback, long)} has been called. Call {@link
+   * #releasePeriod()} to release the period.
    *
    * @param id The identifier that should be used to create the media period from the media source.
    */
   public void createPeriod(MediaPeriodId id) {
-    mediaPeriod = mediaSource.createPeriod(id, allocator);
+    long preparePositionUs = getPreparePositionWithOverride(this.preparePositionUs);
+    mediaPeriod = mediaSource.createPeriod(id, allocator, preparePositionUs);
     if (callback != null) {
-      long preparePositionUs =
-          preparePositionOverrideUs != C.TIME_UNSET
-              ? preparePositionOverrideUs
-              : this.preparePositionUs;
       mediaPeriod.prepare(this, preparePositionUs);
     }
   }
@@ -124,9 +124,8 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
   @Override
   public void prepare(Callback callback, long preparePositionUs) {
     this.callback = callback;
-    this.preparePositionUs = preparePositionUs;
     if (mediaPeriod != null) {
-      mediaPeriod.prepare(this, preparePositionUs);
+      mediaPeriod.prepare(this, getPreparePositionWithOverride(this.preparePositionUs));
     }
   }
 
@@ -217,4 +216,9 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     callback.onPrepared(this);
   }
 
+  private long getPreparePositionWithOverride(long preparePositionUs) {
+    return preparePositionOverrideUs != C.TIME_UNSET
+        ? preparePositionOverrideUs
+        : preparePositionUs;
+  }
 }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
index 07733436cb..9465a8f1a2 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java
@@ -379,7 +379,7 @@ public final class ExtractorMediaSource extends BaseMediaSource
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     DataSource dataSource = dataSourceFactory.createDataSource();
     if (transferListener != null) {
       dataSource.addTransferListener(transferListener);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/LoopingMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/LoopingMediaSource.java
index cac15d5ed9..281465eec3 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/LoopingMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/LoopingMediaSource.java
@@ -80,14 +80,15 @@ public final class LoopingMediaSource extends CompositeMediaSource<Void> {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     if (loopCount == Integer.MAX_VALUE) {
-      return childSource.createPeriod(id, allocator);
+      return childSource.createPeriod(id, allocator, startPositionUs);
     }
     Object childPeriodUid = LoopingTimeline.getChildPeriodUidFromConcatenatedUid(id.periodUid);
     MediaPeriodId childMediaPeriodId = id.copyWithPeriodUid(childPeriodUid);
     childMediaPeriodIdToMediaPeriodId.put(childMediaPeriodId, id);
-    MediaPeriod mediaPeriod = childSource.createPeriod(childMediaPeriodId, allocator);
+    MediaPeriod mediaPeriod =
+        childSource.createPeriod(childMediaPeriodId, allocator, startPositionUs);
     mediaPeriodToChildMediaPeriodId.put(mediaPeriod, childMediaPeriodId);
     return mediaPeriod;
   }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSource.java
index 74449ba16b..801737faef 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSource.java
@@ -35,8 +35,8 @@ import java.io.IOException;
  *       on the {@link SourceInfoRefreshListener}s passed to {@link #prepareSource(ExoPlayer,
  *       boolean, SourceInfoRefreshListener, TransferListener)}.
  *   <li>To provide {@link MediaPeriod} instances for the periods in its timeline. MediaPeriods are
- *       obtained by calling {@link #createPeriod(MediaPeriodId, Allocator)}, and provide a way for
- *       the player to load and read the media.
+ *       obtained by calling {@link #createPeriod(MediaPeriodId, Allocator, long)}, and provide a
+ *       way for the player to load and read the media.
  * </ul>
  *
  * All methods are called on the player's internal playback thread, as described in the {@link
@@ -274,9 +274,10 @@ public interface MediaSource {
    *
    * @param id The identifier of the period.
    * @param allocator An {@link Allocator} from which to obtain media buffer allocations.
+   * @param startPositionUs The expected start position, in microseconds.
    * @return A new {@link MediaPeriod}.
    */
-  MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator);
+  MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs);
 
   /**
    * Releases the period.
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java
index 573e97cb13..cc7202f9b2 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java
@@ -124,13 +124,13 @@ public final class MergingMediaSource extends CompositeMediaSource<Integer> {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     MediaPeriod[] periods = new MediaPeriod[mediaSources.length];
     int periodIndex = timelines[0].getIndexOfPeriod(id.periodUid);
     for (int i = 0; i < periods.length; i++) {
       MediaPeriodId childMediaPeriodId =
           id.copyWithPeriodUid(timelines[i].getUidOfPeriod(periodIndex));
-      periods[i] = mediaSources[i].createPeriod(childMediaPeriodId, allocator);
+      periods[i] = mediaSources[i].createPeriod(childMediaPeriodId, allocator, startPositionUs);
     }
     return new MergingMediaPeriod(compositeSequenceableLoaderFactory, periods);
   }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaSource.java
index 66097970c7..046672bb77 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaSource.java
@@ -318,7 +318,7 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     return new SingleSampleMediaPeriod(
         dataSpec,
         dataSourceFactory,
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdsMediaSource.java b/library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdsMediaSource.java
index 19ddbd2c54..4bf661ddc0 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdsMediaSource.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdsMediaSource.java
@@ -341,7 +341,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     if (adPlaybackState.adGroupCount > 0 && id.isAd()) {
       int adGroupIndex = id.adGroupIndex;
       int adIndexInAdGroup = id.adIndexInAdGroup;
@@ -360,7 +360,8 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
         prepareChildSource(id, adMediaSource);
       }
       MediaSource mediaSource = adGroupMediaSources[adGroupIndex][adIndexInAdGroup];
-      DeferredMediaPeriod deferredMediaPeriod = new DeferredMediaPeriod(mediaSource, id, allocator);
+      DeferredMediaPeriod deferredMediaPeriod =
+          new DeferredMediaPeriod(mediaSource, id, allocator, startPositionUs);
       deferredMediaPeriod.setPrepareErrorListener(
           new AdPrepareErrorListener(adUri, adGroupIndex, adIndexInAdGroup));
       List<DeferredMediaPeriod> mediaPeriods = deferredMediaPeriodByAdMediaSource.get(mediaSource);
@@ -376,7 +377,8 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
       }
       return deferredMediaPeriod;
     } else {
-      DeferredMediaPeriod mediaPeriod = new DeferredMediaPeriod(contentMediaSource, id, allocator);
+      DeferredMediaPeriod mediaPeriod =
+          new DeferredMediaPeriod(contentMediaSource, id, allocator, startPositionUs);
       mediaPeriod.createPeriod(id);
       return mediaPeriod;
     }
diff --git a/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java b/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
index c8de8f02b1..c65bfceb39 100644
--- a/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
+++ b/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
@@ -635,7 +635,8 @@ public final class DashMediaSource extends BaseMediaSource {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId periodId, Allocator allocator) {
+  public MediaPeriod createPeriod(
+      MediaPeriodId periodId, Allocator allocator, long startPositionUs) {
     int periodIndex = (Integer) periodId.periodUid - firstPeriodId;
     EventDispatcher periodEventDispatcher =
         createEventDispatcher(periodId, manifest.getPeriod(periodIndex).startMs);
diff --git a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
index a9b0c579ac..2afd041631 100644
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java
@@ -412,7 +412,7 @@ public final class HlsMediaSource extends BaseMediaSource
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     EventDispatcher eventDispatcher = createEventDispatcher(id);
     return new HlsMediaPeriod(
         extractorFactory,
diff --git a/library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java b/library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
index 103a52a55a..d025f8fa3a 100644
--- a/library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
+++ b/library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java
@@ -533,7 +533,7 @@ public final class SsMediaSource extends BaseMediaSource
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     EventDispatcher eventDispatcher = createEventDispatcher(id);
     SsMediaPeriod period =
         new SsMediaPeriod(
diff --git a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
index 1f0c0c1a40..999372b90a 100644
--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
@@ -116,7 +116,7 @@ public class FakeMediaSource extends BaseMediaSource {
   }
 
   @Override
-  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
+  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
     assertThat(preparedSource).isTrue();
     assertThat(releasedSource).isFalse();
     int periodIndex = timeline.getIndexOfPeriod(id.periodUid);
diff --git a/testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/MediaSourceTestRunner.java b/testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/MediaSourceTestRunner.java
index 70e7669dfb..e6fb5bc5f3 100644
--- a/testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/MediaSourceTestRunner.java
+++ b/testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/MediaSourceTestRunner.java
@@ -142,15 +142,28 @@ public class MediaSourceTestRunner {
   }
 
   /**
-   * Calls {@link MediaSource#createPeriod(MediaSource.MediaPeriodId, Allocator)} on the playback
-   * thread, asserting that a non-null {@link MediaPeriod} is returned.
+   * Calls {@link MediaSource#createPeriod(MediaSource.MediaPeriodId, Allocator, long)} with a zero
+   * start position on the playback thread, asserting that a non-null {@link MediaPeriod} is
+   * returned.
    *
    * @param periodId The id of the period to create.
    * @return The created {@link MediaPeriod}.
    */
   public MediaPeriod createPeriod(final MediaPeriodId periodId) {
+    return createPeriod(periodId, /* startPositionUs= */ 0);
+  }
+
+  /**
+   * Calls {@link MediaSource#createPeriod(MediaSource.MediaPeriodId, Allocator, long)} on the
+   * playback thread, asserting that a non-null {@link MediaPeriod} is returned.
+   *
+   * @param periodId The id of the period to create.
+   * @return The created {@link MediaPeriod}.
+   */
+  public MediaPeriod createPeriod(final MediaPeriodId periodId, long startPositionUs) {
     final MediaPeriod[] holder = new MediaPeriod[1];
-    runOnPlaybackThread(() -> holder[0] = mediaSource.createPeriod(periodId, allocator));
+    runOnPlaybackThread(
+        () -> holder[0] = mediaSource.createPeriod(periodId, allocator, startPositionUs));
     assertThat(holder[0]).isNotNull();
     return holder[0];
   }