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 e73fdd58a3..c031fcde21 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
@@ -456,8 +456,8 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
       holder = new MediaSourceHolder(new DummyMediaSource());
       holder.hasStartedPreparing = true;
     }
-    DeferredMediaPeriod mediaPeriod =
-        new DeferredMediaPeriod(holder.mediaSource, id, allocator, startPositionUs);
+    MaskingMediaPeriod mediaPeriod =
+        new MaskingMediaPeriod(holder.mediaSource, id, allocator, startPositionUs);
     mediaSourceByMediaPeriod.put(mediaPeriod, holder);
     holder.activeMediaPeriods.add(mediaPeriod);
     if (!holder.hasStartedPreparing) {
@@ -474,7 +474,7 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
   public final void releasePeriod(MediaPeriod mediaPeriod) {
     MediaSourceHolder holder =
         Assertions.checkNotNull(mediaSourceByMediaPeriod.remove(mediaPeriod));
-    ((DeferredMediaPeriod) mediaPeriod).releasePeriod();
+    ((MaskingMediaPeriod) mediaPeriod).releasePeriod();
     holder.activeMediaPeriods.remove(mediaPeriod);
     maybeReleaseChildSource(holder);
   }
@@ -784,7 +784,7 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
       // is unset and we don't load beyond periods with unset duration. We need to figure out how to
       // handle the prepare positions of multiple deferred media periods, should that ever change.
       Assertions.checkState(mediaSourceHolder.activeMediaPeriods.size() <= 1);
-      DeferredMediaPeriod deferredMediaPeriod =
+      MaskingMediaPeriod deferredMediaPeriod =
           mediaSourceHolder.activeMediaPeriods.isEmpty()
               ? null
               : mediaSourceHolder.activeMediaPeriods.get(0);
@@ -897,7 +897,7 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
 
     public final MediaSource mediaSource;
     public final Object uid;
-    public final List<DeferredMediaPeriod> activeMediaPeriods;
+    public final List<MaskingMediaPeriod> activeMediaPeriods;
 
     public DeferredTimeline timeline;
     public int childIndex;
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/MaskingMediaPeriod.java
similarity index 94%
rename from library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java
rename to library/core/src/main/java/com/google/android/exoplayer2/source/MaskingMediaPeriod.java
index 95a218bfe7..344c4989eb 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/MaskingMediaPeriod.java
@@ -32,7 +32,7 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
  * #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.
  */
-public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callback {
+public final class MaskingMediaPeriod implements MediaPeriod, MediaPeriod.Callback {
 
   /** Listener for preparation errors. */
   public interface PrepareErrorListener {
@@ -45,7 +45,7 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   /** The {@link MediaSource} which will create the actual media period. */
   public final MediaSource mediaSource;
-  /** The {@link MediaPeriodId} used to create the deferred media period. */
+  /** The {@link MediaPeriodId} used to create the masking media period. */
   public final MediaPeriodId id;
 
   private final Allocator allocator;
@@ -58,14 +58,14 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
   private long preparePositionOverrideUs;
 
   /**
-   * Creates a new deferred media period.
+   * Creates a new masking media period.
    *
    * @param mediaSource The media source to wrap.
-   * @param id The identifier used to create the deferred media period.
+   * @param id The identifier used to create the masking media period.
    * @param allocator The allocator used to create the media period.
    * @param preparePositionUs The expected start position, in microseconds.
    */
-  public DeferredMediaPeriod(
+  public MaskingMediaPeriod(
       MediaSource mediaSource, MediaPeriodId id, Allocator allocator, long preparePositionUs) {
     this.id = id;
     this.allocator = allocator;
@@ -85,7 +85,7 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     this.listener = listener;
   }
 
-  /** Returns the position at which the deferred media period was prepared, in microseconds. */
+  /** Returns the position at which the masking media period was prepared, in microseconds. */
   public long getPreparePositionUs() {
     return preparePositionUs;
   }
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 78b0f6de11..dd4c0d26b2 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
@@ -23,7 +23,7 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.source.CompositeMediaSource;
-import com.google.android.exoplayer2.source.DeferredMediaPeriod;
+import com.google.android.exoplayer2.source.MaskingMediaPeriod;
 import com.google.android.exoplayer2.source.MediaPeriod;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.MediaSource.MediaPeriodId;
@@ -128,7 +128,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
   private final AdsLoader adsLoader;
   private final AdsLoader.AdViewProvider adViewProvider;
   private final Handler mainHandler;
-  private final Map<MediaSource, List<DeferredMediaPeriod>> deferredMediaPeriodByAdMediaSource;
+  private final Map<MediaSource, List<MaskingMediaPeriod>> maskingMediaPeriodByAdMediaSource;
   private final Timeline.Period period;
 
   // Accessed on the player thread.
@@ -179,7 +179,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
     this.adsLoader = adsLoader;
     this.adViewProvider = adViewProvider;
     mainHandler = new Handler(Looper.getMainLooper());
-    deferredMediaPeriodByAdMediaSource = new HashMap<>();
+    maskingMediaPeriodByAdMediaSource = new HashMap<>();
     period = new Timeline.Period();
     adGroupMediaSources = new MediaSource[0][];
     adGroupTimelines = new Timeline[0][];
@@ -219,29 +219,29 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
       if (mediaSource == null) {
         mediaSource = adMediaSourceFactory.createMediaSource(adUri);
         adGroupMediaSources[adGroupIndex][adIndexInAdGroup] = mediaSource;
-        deferredMediaPeriodByAdMediaSource.put(mediaSource, new ArrayList<>());
+        maskingMediaPeriodByAdMediaSource.put(mediaSource, new ArrayList<>());
         prepareChildSource(id, mediaSource);
       }
-      DeferredMediaPeriod deferredMediaPeriod =
-          new DeferredMediaPeriod(mediaSource, id, allocator, startPositionUs);
-      deferredMediaPeriod.setPrepareErrorListener(
+      MaskingMediaPeriod maskingMediaPeriod =
+          new MaskingMediaPeriod(mediaSource, id, allocator, startPositionUs);
+      maskingMediaPeriod.setPrepareErrorListener(
           new AdPrepareErrorListener(adUri, adGroupIndex, adIndexInAdGroup));
-      List<DeferredMediaPeriod> mediaPeriods = deferredMediaPeriodByAdMediaSource.get(mediaSource);
+      List<MaskingMediaPeriod> mediaPeriods = maskingMediaPeriodByAdMediaSource.get(mediaSource);
       if (mediaPeriods == null) {
         Object periodUid =
             Assertions.checkNotNull(adGroupTimelines[adGroupIndex][adIndexInAdGroup])
                 .getUidOfPeriod(/* periodIndex= */ 0);
         MediaPeriodId adSourceMediaPeriodId = new MediaPeriodId(periodUid, id.windowSequenceNumber);
-        deferredMediaPeriod.createPeriod(adSourceMediaPeriodId);
+        maskingMediaPeriod.createPeriod(adSourceMediaPeriodId);
       } else {
-        // Keep track of the deferred media period so it can be populated with the real media period
+        // Keep track of the masking media period so it can be populated with the real media period
         // when the source's info becomes available.
-        mediaPeriods.add(deferredMediaPeriod);
+        mediaPeriods.add(maskingMediaPeriod);
       }
-      return deferredMediaPeriod;
+      return maskingMediaPeriod;
     } else {
-      DeferredMediaPeriod mediaPeriod =
-          new DeferredMediaPeriod(contentMediaSource, id, allocator, startPositionUs);
+      MaskingMediaPeriod mediaPeriod =
+          new MaskingMediaPeriod(contentMediaSource, id, allocator, startPositionUs);
       mediaPeriod.createPeriod(id);
       return mediaPeriod;
     }
@@ -249,13 +249,13 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
 
   @Override
   public void releasePeriod(MediaPeriod mediaPeriod) {
-    DeferredMediaPeriod deferredMediaPeriod = (DeferredMediaPeriod) mediaPeriod;
-    List<DeferredMediaPeriod> mediaPeriods =
-        deferredMediaPeriodByAdMediaSource.get(deferredMediaPeriod.mediaSource);
+    MaskingMediaPeriod maskingMediaPeriod = (MaskingMediaPeriod) mediaPeriod;
+    List<MaskingMediaPeriod> mediaPeriods =
+        maskingMediaPeriodByAdMediaSource.get(maskingMediaPeriod.mediaSource);
     if (mediaPeriods != null) {
-      mediaPeriods.remove(deferredMediaPeriod);
+      mediaPeriods.remove(maskingMediaPeriod);
     }
-    deferredMediaPeriod.releasePeriod();
+    maskingMediaPeriod.releasePeriod();
   }
 
   @Override
@@ -263,7 +263,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
     super.releaseSourceInternal();
     Assertions.checkNotNull(componentListener).release();
     componentListener = null;
-    deferredMediaPeriodByAdMediaSource.clear();
+    maskingMediaPeriodByAdMediaSource.clear();
     contentTimeline = null;
     contentManifest = null;
     adPlaybackState = null;
@@ -319,11 +319,11 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
       int adIndexInAdGroup, Timeline timeline) {
     Assertions.checkArgument(timeline.getPeriodCount() == 1);
     adGroupTimelines[adGroupIndex][adIndexInAdGroup] = timeline;
-    List<DeferredMediaPeriod> mediaPeriods = deferredMediaPeriodByAdMediaSource.remove(mediaSource);
+    List<MaskingMediaPeriod> mediaPeriods = maskingMediaPeriodByAdMediaSource.remove(mediaSource);
     if (mediaPeriods != null) {
       Object periodUid = timeline.getUidOfPeriod(/* periodIndex= */ 0);
       for (int i = 0; i < mediaPeriods.size(); i++) {
-        DeferredMediaPeriod mediaPeriod = mediaPeriods.get(i);
+        MaskingMediaPeriod mediaPeriod = mediaPeriods.get(i);
         MediaPeriodId adSourceMediaPeriodId =
             new MediaPeriodId(periodUid, mediaPeriod.id.windowSequenceNumber);
         mediaPeriod.createPeriod(adSourceMediaPeriodId);
@@ -413,7 +413,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
     }
   }
 
-  private final class AdPrepareErrorListener implements DeferredMediaPeriod.PrepareErrorListener {
+  private final class AdPrepareErrorListener implements MaskingMediaPeriod.PrepareErrorListener {
 
     private final Uri adUri;
     private final int adGroupIndex;