Propagate segment properties when merging HLS delta updates

Issue: #5011 PiperOrigin-RevId: 350540152

Propagate segment properties when merging HLS delta updates
Issue: #5011 PiperOrigin-RevId: 350540152
b05fa731 · bachinger · Ian Baker · fc3b91c9 · b05fa731 · b05fa731
Commit b05fa731 authored Jan 07, 2021 by bachinger Committed by Ian Baker Jan 08, 2021
Showing with 232 additions and 114 deletions
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistParserFactory.java
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTracker.java
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/FilteringHlsPlaylistParserFactory.java
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylist.java
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParserFactory.java
library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTrackerTest.java
library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylistParserTest.java
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistParserFactory.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistParserFactory.java
@@ -15,6 +15,7 @@
 */
 package com.google.android.exoplayer2.source.hls.playlist;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.ParsingLoadable;
 /** Default implementation for {@link HlsPlaylistParserFactory}. */
@@ -27,7 +28,7 @@ public final class DefaultHlsPlaylistParserFactory implements HlsPlaylistParserF
  @Override
  public ParsingLoadable.Parser<HlsPlaylist> createPlaylistParser(
-      HlsMasterPlaylist masterPlaylist) {
+      HlsMasterPlaylist masterPlaylist, @Nullable HlsMediaPlaylist previousMediaPlaylist) {
-    return new HlsPlaylistParser(masterPlaylist);
+    return new HlsPlaylistParser(masterPlaylist, previousMediaPlaylist);
  }
 }
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTracker.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTracker.java
@@ -68,7 +68,6 @@ public final class DefaultHlsPlaylistTracker
  private final List<PlaylistEventListener> listeners;
  private final double playlistStuckTargetDurationCoefficient;
-  @Nullable private ParsingLoadable.Parser<HlsPlaylist> mediaPlaylistParser;
  @Nullable private EventDispatcher eventDispatcher;
  @Nullable private Loader initialPlaylistLoader;
  @Nullable private Handler playlistRefreshHandler;
@@ -243,7 +242,6 @@ public final class DefaultHlsPlaylistTracker
      masterPlaylist = (HlsMasterPlaylist) result;
    }
    this.masterPlaylist = masterPlaylist;
-    mediaPlaylistParser = playlistParserFactory.createPlaylistParser(masterPlaylist);
    primaryMediaPlaylistUrl = masterPlaylist.variants.get(0).url;
    createBundles(masterPlaylist.mediaPlaylistUrls);
    LoadEventInfo loadEventInfo =
@@ -671,6 +669,8 @@ public final class DefaultHlsPlaylistTracker
    }
    private void loadPlaylistImmediately(Uri playlistRequestUri) {
+      ParsingLoadable.Parser<HlsPlaylist> mediaPlaylistParser =
+          playlistParserFactory.createPlaylistParser(masterPlaylist, playlistSnapshot);
      ParsingLoadable<HlsPlaylist> mediaPlaylistLoadable =
          new ParsingLoadable<>(
              mediaPlaylistDataSource,
@@ -691,10 +691,6 @@ public final class DefaultHlsPlaylistTracker
    private void processLoadedPlaylist(
        HlsMediaPlaylist loadedPlaylist, LoadEventInfo loadEventInfo) {
      @Nullable HlsMediaPlaylist oldPlaylist = playlistSnapshot;
-      loadedPlaylist =
-          loadedPlaylist.skippedSegmentCount > 0
-              ? loadedPlaylist.expandSkippedSegments(checkNotNull(playlistSnapshot))
-              : loadedPlaylist;
      long currentTimeMs = SystemClock.elapsedRealtime();
      lastSnapshotLoadMs = currentTimeMs;
      playlistSnapshot = getLatestPlaylistSnapshot(oldPlaylist, loadedPlaylist);
@@ -759,9 +755,7 @@ public final class DefaultHlsPlaylistTracker
      Uri.Builder uriBuilder = playlistUrl.buildUpon();
      if (playlistSnapshot.serverControl.canBlockReload) {
        long targetMediaSequence =
-            playlistSnapshot.mediaSequence
+            playlistSnapshot.mediaSequence + playlistSnapshot.segments.size();
-                + playlistSnapshot.segments.size()
-                + playlistSnapshot.skippedSegmentCount;
        uriBuilder.appendQueryParameter(BLOCK_MSN_PARAM, String.valueOf(targetMediaSequence));
        if (playlistSnapshot.partTargetDurationUs != C.TIME_UNSET) {
          List<Part> trailingParts = playlistSnapshot.trailingParts;
@@ -774,9 +768,8 @@ public final class DefaultHlsPlaylistTracker
        }
      }
      if (playlistSnapshot.serverControl.skipUntilUs != C.TIME_UNSET) {
-        // TODO: Fix skipped segment merging before re-enabling.
+        uriBuilder.appendQueryParameter(
-        // uriBuilder.appendQueryParameter(
+            SKIP_PARAM, playlistSnapshot.serverControl.canSkipDateRanges ? "v2" : "YES");
-        //    SKIP_PARAM, playlistSnapshot.serverControl.canSkipDateRanges ? "v2" : "YES");
      }
      return uriBuilder.build();
    }

--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/FilteringHlsPlaylistParserFactory.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/FilteringHlsPlaylistParserFactory.java
@@ -15,6 +15,7 @@
 */
 package com.google.android.exoplayer2.source.hls.playlist;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.offline.FilteringManifestParser;
 import com.google.android.exoplayer2.offline.StreamKey;
 import com.google.android.exoplayer2.upstream.ParsingLoadable;
@@ -48,8 +49,9 @@ public final class FilteringHlsPlaylistParserFactory implements HlsPlaylistParse
  @Override
  public ParsingLoadable.Parser<HlsPlaylist> createPlaylistParser(
-      HlsMasterPlaylist masterPlaylist) {
+      HlsMasterPlaylist masterPlaylist, @Nullable HlsMediaPlaylist previousMediaPlaylist) {
    return new FilteringManifestParser<>(
-        hlsPlaylistParserFactory.createPlaylistParser(masterPlaylist), streamKeys);
+        hlsPlaylistParserFactory.createPlaylistParser(masterPlaylist, previousMediaPlaylist),
+        streamKeys);
  }
 }
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylist.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylist.java
@@ -15,7 +15,6 @@
 */
 package com.google.android.exoplayer2.source.hls.playlist;
-import static com.google.android.exoplayer2.util.Assertions.checkArgument;
 import android.net.Uri;
 import androidx.annotation.IntDef;
@@ -170,6 +169,30 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
      this.title = title;
      this.parts = ImmutableList.copyOf(parts);
    }
+    public Segment copyWith(long relativeStartTimeUs, int relativeDiscontinuitySequence) {
+      List<Part> updatedParts = new ArrayList<>();
+      long relativePartStartTimeUs = relativeStartTimeUs;
+      for (int i = 0; i < parts.size(); i++) {
+        Part part = parts.get(i);
+        updatedParts.add(part.copyWith(relativePartStartTimeUs, relativeDiscontinuitySequence));
+        relativePartStartTimeUs += part.durationUs;
+      }
+      return new Segment(
+          url,
+          initializationSegment,
+          title,
+          durationUs,
+          relativeDiscontinuitySequence,
+          relativeStartTimeUs,
+          drmInitData,
+          fullSegmentEncryptionKeyUri,
+          encryptionIV,
+          byteRangeOffset,
+          byteRangeLength,
+          hasGapTag,
+          updatedParts);
+    }
  }
  /** A media part. */
@@ -226,6 +249,23 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
      this.isIndependent = isIndependent;
      this.isPreload = isPreload;
    }
+    public Part copyWith(long relativeStartTimeUs, int relativeDiscontinuitySequence) {
+      return new Part(
+          url,
+          initializationSegment,
+          durationUs,
+          relativeDiscontinuitySequence,
+          relativeStartTimeUs,
+          drmInitData,
+          fullSegmentEncryptionKeyUri,
+          encryptionIV,
+          byteRangeOffset,
+          byteRangeLength,
+          hasGapTag,
+          isIndependent,
+          isPreload);
+    }
  }
  /** The base for a {@link Segment} or a {@link Part} required for playback. */
@@ -405,8 +445,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
   * The list of segments in the playlist.
   */
  public final List<Segment> segments;
-  /** The number of skipped segments. */
-  public int skippedSegmentCount;
  /**
   * The list of parts at the end of the playlist for which the segment is not in the playlist yet.
   */
@@ -434,7 +472,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
   * @param hasProgramDateTime See {@link #hasProgramDateTime}.
   * @param protectionSchemes See {@link #protectionSchemes}.
   * @param segments See {@link #segments}.
-   * @param skippedSegmentCount See {@link #skippedSegmentCount}.
   * @param trailingParts See {@link #trailingParts}.
   * @param serverControl See {@link #serverControl}
   * @param renditionReports See {@link #renditionReports}.
@@ -456,7 +493,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
      boolean hasProgramDateTime,
      @Nullable DrmInitData protectionSchemes,
      List<Segment> segments,
-      int skippedSegmentCount,
      List<Part> trailingParts,
      ServerControl serverControl,
      Map<Uri, RenditionReport> renditionReports) {
@@ -473,7 +509,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
    this.hasProgramDateTime = hasProgramDateTime;
    this.protectionSchemes = protectionSchemes;
    this.segments = ImmutableList.copyOf(segments);
-    this.skippedSegmentCount = skippedSegmentCount;
    this.trailingParts = ImmutableList.copyOf(trailingParts);
    this.renditionReports = ImmutableMap.copyOf(renditionReports);
    if (!trailingParts.isEmpty()) {
@@ -509,10 +544,9 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
      return false;
    }
    // The media sequences are equal.
-    int segmentCount = segments.size() + skippedSegmentCount;
+    int segmentCountDifference = segments.size() - other.segments.size();
-    int otherSegmentCount = other.segments.size() + other.skippedSegmentCount;
+    if (segmentCountDifference != 0) {
-    if (segmentCount != otherSegmentCount) {
+      return segmentCountDifference > 0;
-      return segmentCount > otherSegmentCount;
    }
    int partCount = trailingParts.size();
    int otherPartCount = other.trailingParts.size();
@@ -528,52 +562,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
  }
  /**
-   * Merges the skipped segments of the previous playlist and returns a copy with a {@link
-   * #skippedSegmentCount} of 0.
-   *
-   * @param previousPlaylist The previous playlist with a {@link #skippedSegmentCount} of zero.
-   * @return A new playlist with a complete list of segments.
-   */
-  public HlsMediaPlaylist expandSkippedSegments(HlsMediaPlaylist previousPlaylist) {
-    if (skippedSegmentCount == 0) {
-      return this;
-    }
-    checkArgument(previousPlaylist.skippedSegmentCount == 0);
-    List<Segment> mergedSegments = new ArrayList<>();
-    long mediaSequence = this.mediaSequence;
-    int startIndex = (int) (mediaSequence - previousPlaylist.mediaSequence);
-    int endIndex = startIndex + skippedSegmentCount;
-    if (startIndex >= 0 && endIndex <= previousPlaylist.segments.size()) {
-      mergedSegments.addAll(previousPlaylist.segments.subList(startIndex, endIndex));
-    } else {
-      // Adjust the media sequence if the old playlist doesn't contain all of the skipped segments.
-      mediaSequence += skippedSegmentCount;
-    }
-    mergedSegments.addAll(segments);
-    return new HlsMediaPlaylist(
-        playlistType,
-        baseUri,
-        tags,
-        startOffsetUs,
-        startTimeUs,
-        hasDiscontinuitySequence,
-        discontinuitySequence,
-        mediaSequence,
-        version,
-        targetDurationUs,
-        partTargetDurationUs,
-        hasIndependentSegments,
-        hasEndTag,
-        hasProgramDateTime,
-        protectionSchemes,
-        mergedSegments,
-        /* skippedSegmentCount= */ 0,
-        trailingParts,
-        serverControl,
-        renditionReports);
-  }
-  /**
   * Returns a playlist identical to this one except for the start time, the discontinuity sequence
   * and {@code hasDiscontinuitySequence} values. The first two are set to the specified values,
   * {@code hasDiscontinuitySequence} is set to true.
@@ -600,7 +588,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
        hasProgramDateTime,
        protectionSchemes,
        segments,
-        skippedSegmentCount,
        trailingParts,
        serverControl,
        renditionReports);
@@ -631,7 +618,6 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
        hasProgramDateTime,
        protectionSchemes,
        segments,
-        skippedSegmentCount,
        trailingParts,
        serverControl,
        renditionReports);

--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
@@ -16,6 +16,8 @@
 package com.google.android.exoplayer2.source.hls.playlist;
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+import static com.google.android.exoplayer2.util.Assertions.checkState;
+import static com.google.android.exoplayer2.util.Util.castNonNull;
 import android.net.Uri;
 import android.text.TextUtils;
@@ -211,13 +213,14 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
      Pattern.compile("\\{\\$([a-zA-Z0-9\\-_]+)\\}");
  private final HlsMasterPlaylist masterPlaylist;
+  @Nullable private final HlsMediaPlaylist previousMediaPlaylist;
  /**
   * Creates an instance where media playlists are parsed without inheriting attributes from a
   * master playlist.
   */
  public HlsPlaylistParser() {
-    this(HlsMasterPlaylist.EMPTY);
+    this(HlsMasterPlaylist.EMPTY, /* previousMediaPlaylist= */ null);
  }
  /**
@@ -225,9 +228,13 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
   * playlist.
   *
   * @param masterPlaylist The master playlist from which media playlists will inherit attributes.
+   * @param previousMediaPlaylist The previous media playlist from which the new media playlist may
+   *     inherit skipped segments.
   */
-  public HlsPlaylistParser(HlsMasterPlaylist masterPlaylist) {
+  public HlsPlaylistParser(
+      HlsMasterPlaylist masterPlaylist, @Nullable HlsMediaPlaylist previousMediaPlaylist) {
    this.masterPlaylist = masterPlaylist;
+    this.previousMediaPlaylist = previousMediaPlaylist;
  }
  @Override
@@ -257,7 +264,10 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
            || line.equals(TAG_ENDLIST)) {
          extraLines.add(line);
          return parseMediaPlaylist(
-              masterPlaylist, new LineIterator(extraLines, reader), uri.toString());
+              masterPlaylist,
+              previousMediaPlaylist,
+              new LineIterator(extraLines, reader),
+              uri.toString());
        } else {
          extraLines.add(line);
        }
@@ -603,7 +613,11 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
  }
  private static HlsMediaPlaylist parseMediaPlaylist(
-      HlsMasterPlaylist masterPlaylist, LineIterator iterator, String baseUri) throws IOException {
+      HlsMasterPlaylist masterPlaylist,
+      @Nullable HlsMediaPlaylist previousMediaPlaylist,
+      LineIterator iterator,
+      String baseUri)
+      throws IOException {
    @HlsMediaPlaylist.PlaylistType int playlistType = HlsMediaPlaylist.PLAYLIST_TYPE_UNKNOWN;
    long startOffsetUs = C.TIME_UNSET;
    long mediaSequence = 0;
@@ -642,7 +656,6 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
            /* holdBackUs= */ C.TIME_UNSET,
            /* partHoldBackUs= */ C.TIME_UNSET,
            /* canBlockReload= */ false);
-    int skippedSegmentCount = 0;
    @Nullable DrmInitData playlistProtectionSchemes = null;
    @Nullable String fullSegmentEncryptionKeyUri = null;
@@ -727,7 +740,41 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
            (long) (parseDoubleAttr(line, REGEX_MEDIA_DURATION) * C.MICROS_PER_SECOND);
        segmentTitle = parseOptionalStringAttr(line, REGEX_MEDIA_TITLE, "", variableDefinitions);
      } else if (line.startsWith(TAG_SKIP)) {
-        skippedSegmentCount = parseIntAttr(line, REGEX_SKIPPED_SEGMENTS);
+        int skippedSegmentCount = parseIntAttr(line, REGEX_SKIPPED_SEGMENTS);
+        checkState(previousMediaPlaylist != null && segments.isEmpty());
+        int startIndex = (int) (mediaSequence - castNonNull(previousMediaPlaylist).mediaSequence);
+        int endIndex = startIndex + skippedSegmentCount;
+        if (startIndex >= 0 && endIndex <= previousMediaPlaylist.segments.size()) {
+          // Merge only if all skipped segments are available in the previous playlist.
+          for (int i = startIndex; i < endIndex; i++) {
+            Segment segment = previousMediaPlaylist.segments.get(i);
+            if (mediaSequence != previousMediaPlaylist.mediaSequence) {
+              // If the media sequences of the playlists are not the same, we need to recreate the
+              // object with the updated relative start time and the relative discontinuity
+              // sequence. With identical playlist media sequences these values do not change.
+              int newRelativeDiscontinuitySequence =
+                  previousMediaPlaylist.discontinuitySequence
+                      - playlistDiscontinuitySequence
+                      + segment.relativeDiscontinuitySequence;
+              segment = segment.copyWith(segmentStartTimeUs, newRelativeDiscontinuitySequence);
+            }
+            segments.add(segment);
+            segmentStartTimeUs += segment.durationUs;
+            partStartTimeUs = segmentStartTimeUs;
+            if (segment.byteRangeLength != C.LENGTH_UNSET) {
+              segmentByteRangeOffset = segment.byteRangeOffset + segment.byteRangeLength;
+            }
+            relativeDiscontinuitySequence = segment.relativeDiscontinuitySequence;
+            initializationSegment = segment.initializationSegment;
+            cachedDrmInitData = segment.drmInitData;
+            fullSegmentEncryptionKeyUri = segment.fullSegmentEncryptionKeyUri;
+            if (segment.encryptionIV == null
+                || !segment.encryptionIV.equals(Long.toHexString(segmentMediaSequence))) {
+              fullSegmentEncryptionIV = segment.encryptionIV;
+            }
+            segmentMediaSequence++;
+          }
+        }
      } else if (line.startsWith(TAG_KEY)) {
        String method = parseStringAttr(line, REGEX_METHOD, variableDefinitions);
        String keyFormat =
@@ -972,7 +1019,6 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
        /* hasProgramDateTime= */ playlistStartTimeUs != 0,
        playlistProtectionSchemes,
        segments,
-        skippedSegmentCount,
        trailingParts,
        serverControl,
        renditionReports);

--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParserFactory.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParserFactory.java
@@ -15,6 +15,7 @@
 */
 package com.google.android.exoplayer2.source.hls.playlist;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.ParsingLoadable;
 /** Factory for {@link HlsPlaylist} parsers. */
@@ -32,7 +33,10 @@ public interface HlsPlaylistParserFactory {
   * {@code masterPlaylist}.
   *
   * @param masterPlaylist The master playlist that referenced any parsed media playlists.
+   * @param previousMediaPlaylist The previous media playlist or null if there is no previous media
+   *     playlist.
   * @return A parser for HLS playlists.
   */
-  ParsingLoadable.Parser<HlsPlaylist> createPlaylistParser(HlsMasterPlaylist masterPlaylist);
+  ParsingLoadable.Parser<HlsPlaylist> createPlaylistParser(
+      HlsMasterPlaylist masterPlaylist, @Nullable HlsMediaPlaylist previousMediaPlaylist);
 }
--- a/library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTrackerTest.java
+++ b/library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/DefaultHlsPlaylistTrackerTest.java
@@ -24,7 +24,7 @@ import com.google.android.exoplayer2.robolectric.RobolectricUtil;
 import com.google.android.exoplayer2.source.MediaSourceEventListener;
 import com.google.android.exoplayer2.testutil.TestUtil;
 import com.google.android.exoplayer2.upstream.DataSource;
-import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
+import com.google.android.exoplayer2.upstream.DefaultHttpDataSource;
 import com.google.android.exoplayer2.upstream.DefaultLoadErrorHandlingPolicy;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -116,7 +116,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -128,14 +128,12 @@ public class DefaultHlsPlaylistTrackerTest {
    assertThat(firstFullPlaylist.segments).hasSize(6);
    HlsMediaPlaylist secondFullPlaylist = mediaPlaylists.get(1);
    assertThat(secondFullPlaylist.mediaSequence).isEqualTo(11);
-    assertThat(secondFullPlaylist.skippedSegmentCount).isEqualTo(0);
    assertThat(secondFullPlaylist.segments.get(0).url).isEqualTo("fileSequence11.ts");
    assertThat(secondFullPlaylist.segments.get(5).url).isEqualTo("fileSequence16.ts");
    assertThat(secondFullPlaylist.segments).hasSize(6);
    assertThat(secondFullPlaylist.segments).containsNoneIn(firstFullPlaylist.segments);
  }
-  @Ignore // Test disabled because playlist delta updates are temporarily disabled.
  @Test
  public void start_playlistCanSkip_requestsDeltaUpdateAndExpandsSkippedSegments()
      throws IOException, TimeoutException, InterruptedException {
@@ -150,7 +148,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -160,14 +158,14 @@ public class DefaultHlsPlaylistTrackerTest {
    assertThat(initialPlaylistWithAllSegments.segments).hasSize(6);
    HlsMediaPlaylist mergedPlaylist = mediaPlaylists.get(1);
    assertThat(mergedPlaylist.mediaSequence).isEqualTo(11);
-    assertThat(mergedPlaylist.skippedSegmentCount).isEqualTo(0);
    assertThat(mergedPlaylist.segments).hasSize(6);
    // First 2 segments of the merged playlist need to be copied from the previous playlist.
-    assertThat(mergedPlaylist.segments.subList(0, 2))
+    assertThat(mergedPlaylist.segments.get(0).url)
-        .containsExactlyElementsIn(initialPlaylistWithAllSegments.segments.subList(1, 3))
+        .isEqualTo(initialPlaylistWithAllSegments.segments.get(1).url);
-        .inOrder();
+    assertThat(mergedPlaylist.segments.get(0).relativeStartTimeUs).isEqualTo(0);
-    assertThat(mergedPlaylist.segments.get(2).url)
+    assertThat(mergedPlaylist.segments.get(1).url)
-        .isEqualTo(initialPlaylistWithAllSegments.segments.get(3).url);
+        .isEqualTo(initialPlaylistWithAllSegments.segments.get(2).url);
+    assertThat(mergedPlaylist.segments.get(1).relativeStartTimeUs).isEqualTo(4000000);
  }
  @Ignore // Test disabled because playlist delta updates are temporarily disabled.
@@ -185,7 +183,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -195,11 +193,9 @@ public class DefaultHlsPlaylistTrackerTest {
    assertThat(initialPlaylistWithAllSegments.segments).hasSize(6);
    HlsMediaPlaylist mergedPlaylist = mediaPlaylists.get(1);
    assertThat(mergedPlaylist.mediaSequence).isEqualTo(22);
-    assertThat(mergedPlaylist.skippedSegmentCount).isEqualTo(0);
    assertThat(mergedPlaylist.segments).hasSize(4);
  }
-  @Ignore // Test disabled because playlist delta updates are temporarily disabled.
  @Test
  public void start_playlistCanSkipDataRanges_requestsDeltaUpdateV2()
      throws IOException, TimeoutException, InterruptedException {
@@ -214,7 +210,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -224,7 +220,6 @@ public class DefaultHlsPlaylistTrackerTest {
    assertThat(mediaPlaylists.get(1).mediaSequence).isEqualTo(11);
  }
-  @Ignore // Test disabled because playlist delta updates are temporarily disabled.
  @Test
  public void start_playlistCanSkipAndUriWithParams_preservesOriginalParams()
      throws IOException, TimeoutException, InterruptedException {
@@ -241,7 +236,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -266,7 +261,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -292,7 +287,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -321,7 +316,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -352,7 +347,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            new DefaultHttpDataSourceFactory(),
+            new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 2);
@@ -365,7 +360,6 @@ public class DefaultHlsPlaylistTrackerTest {
    assertThat(mediaPlaylists.get(1).trailingParts).hasSize(2);
  }
-  @Ignore // Test disabled because playlist delta updates are temporarily disabled.
  @Test
  public void start_httpBadRequest_forcesFullNonBlockingPlaylistRequest()
      throws IOException, TimeoutException, InterruptedException {
@@ -386,7 +380,7 @@ public class DefaultHlsPlaylistTrackerTest {
    List<HlsMediaPlaylist> mediaPlaylists =
        runPlaylistTrackerAndCollectMediaPlaylists(
-            /* dataSourceFactory= */ new DefaultHttpDataSourceFactory(),
+            /* dataSourceFactory= */ new DefaultHttpDataSource.Factory(),
            Uri.parse(mockWebServer.url("/master.m3u8").toString()),
            /* awaitedMediaPlaylistCount= */ 3);

--- a/library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylistParserTest.java
+++ b/library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylistParserTest.java
@@ -303,24 +303,112 @@ public class HlsMediaPlaylistParserTest {
  }
  @Test
-  public void parseMediaPlaylist_withSkippedSegments_parsesNumberOfSkippedSegments()
+  public void parseMediaPlaylist_withSkippedSegments_correctlyMergedSegments() throws IOException {
-      throws IOException {
    Uri playlistUri = Uri.parse("https://example.com/test.m3u8");
-    String playlistString =
+    String previousPlaylistString =
        "#EXTM3U\n"
            + "#EXT-X-TARGETDURATION:4\n"
            + "#EXT-X-VERSION:6\n"
+            + "#EXT-X-DISCONTINUITY-SEQUENCE:1234\n"
            + "#EXT-X-SERVER-CONTROL:CAN-SKIP-UNTIL=24.0\n"
-            + "#EXT-X-MEDIA-SEQUENCE:266\n"
+            + "#EXT-X-MEDIA-SEQUENCE:263\n"
-            + "#EXT-X-SKIP:SKIPPED-SEGMENTS=1234\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence264.mp4\n"
+            + "#EXT-X-DISCONTINUITY\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence265.mp4\n"
            + "#EXTINF:4.00008,\n"
            + "fileSequence266.mp4";
+    String playlistString =
+        "#EXTM3U\n"
+            + "#EXT-X-TARGETDURATION:4\n"
+            + "#EXT-X-VERSION:6\n"
+            + "#EXT-X-DISCONTINUITY-SEQUENCE:1234\n"
+            + "#EXT-X-SERVER-CONTROL:CAN-SKIP-UNTIL=24.0\n"
+            + "#EXT-X-MEDIA-SEQUENCE:265\n"
+            + "#EXT-X-SKIP:SKIPPED-SEGMENTS=1\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence266.mp4"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence267.mp4\n";
+    InputStream previousInputStream =
+        new ByteArrayInputStream(Util.getUtf8Bytes(previousPlaylistString));
+    HlsMediaPlaylist previousPlaylist =
+        (HlsMediaPlaylist) new HlsPlaylistParser().parse(playlistUri, previousInputStream);
    InputStream inputStream = new ByteArrayInputStream(Util.getUtf8Bytes(playlistString));
    HlsMediaPlaylist playlist =
-        (HlsMediaPlaylist) new HlsPlaylistParser().parse(playlistUri, inputStream);
+        (HlsMediaPlaylist)
+            new HlsPlaylistParser(HlsMasterPlaylist.EMPTY, previousPlaylist)
+                .parse(playlistUri, inputStream);
+    assertThat(playlist.segments).hasSize(3);
+    assertThat(playlist.segments.get(1).relativeStartTimeUs).isEqualTo(4000079);
+    assertThat(previousPlaylist.segments.get(0).relativeDiscontinuitySequence).isEqualTo(0);
+    assertThat(previousPlaylist.segments.get(1).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(previousPlaylist.segments.get(2).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(0).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(1).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(2).relativeDiscontinuitySequence).isEqualTo(1);
+  }
+  @Test
+  public void parseMediaPlaylist_withSkippedSegments_correctlyMergedParts() throws IOException {
+    Uri playlistUri = Uri.parse("https://example.com/test.m3u8");
+    String previousPlaylistString =
+        "#EXTM3U\n"
+            + "#EXT-X-TARGETDURATION:4\n"
+            + "#EXT-X-VERSION:6\n"
+            + "#EXT-X-DISCONTINUITY-SEQUENCE:1234\n"
+            + "#EXT-X-SERVER-CONTROL:CAN-SKIP-UNTIL=24.0\n"
+            + "#EXT-X-MEDIA-SEQUENCE:264\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part264.1.ts\"\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part264.2.ts\"\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence264.mp4\n"
+            + "#EXT-X-DISCONTINUITY\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part265.1.ts\"\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part265.2.ts\"\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence265.mp4\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part266.1.ts\"\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part266.2.ts\"\n"
+            + "#EXTINF:4.00008,\n"
+            + "fileSequence266.mp4\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part267.1.ts\"";
+    String playlistString =
+        "#EXTM3U\n"
+            + "#EXT-X-TARGETDURATION:4\n"
+            + "#EXT-X-VERSION:6\n"
+            + "#EXT-X-DISCONTINUITY-SEQUENCE:1234\n"
+            + "#EXT-X-SERVER-CONTROL:CAN-SKIP-UNTIL=24.0\n"
+            + "#EXT-X-MEDIA-SEQUENCE:265\n"
+            + "#EXT-X-SKIP:SKIPPED-SEGMENTS=2\n"
+            + "#EXT-X-PART:DURATION=2.00000,URI=\"part267.1.ts\"";
+    InputStream previousInputStream =
+        new ByteArrayInputStream(Util.getUtf8Bytes(previousPlaylistString));
+    HlsMediaPlaylist previousPlaylist =
+        (HlsMediaPlaylist) new HlsPlaylistParser().parse(playlistUri, previousInputStream);
+    InputStream inputStream = new ByteArrayInputStream(Util.getUtf8Bytes(playlistString));
-    assertThat(playlist.skippedSegmentCount).isEqualTo(1234);
+    HlsMediaPlaylist playlist =
+        (HlsMediaPlaylist)
+            new HlsPlaylistParser(HlsMasterPlaylist.EMPTY, previousPlaylist)
+                .parse(playlistUri, inputStream);
+    assertThat(playlist.segments).hasSize(2);
+    assertThat(playlist.segments.get(0).relativeStartTimeUs).isEqualTo(0);
+    assertThat(playlist.segments.get(0).parts.get(0).relativeStartTimeUs).isEqualTo(0);
+    assertThat(playlist.segments.get(0).parts.get(0).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(0).parts.get(1).relativeStartTimeUs).isEqualTo(2000000);
+    assertThat(playlist.segments.get(0).parts.get(1).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(1).relativeStartTimeUs).isEqualTo(4000079);
+    assertThat(playlist.segments.get(1).parts.get(0).relativeStartTimeUs).isEqualTo(4000079);
+    assertThat(playlist.segments.get(1).parts.get(1).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.segments.get(1).parts.get(1).relativeStartTimeUs).isEqualTo(6000079);
+    assertThat(playlist.segments.get(1).parts.get(1).relativeDiscontinuitySequence).isEqualTo(1);
+    assertThat(playlist.trailingParts.get(0).relativeStartTimeUs).isEqualTo(8000158);
+    assertThat(playlist.trailingParts.get(0).relativeDiscontinuitySequence).isEqualTo(1);
  }
  @Test
@@ -1125,7 +1213,9 @@ public class HlsMediaPlaylistParserTest {
            /* variableDefinitions= */ Collections.emptyMap(),
            /* sessionKeyDrmInitData= */ Collections.emptyList());
    HlsMediaPlaylist playlistWithInheritance =
-        (HlsMediaPlaylist) new HlsPlaylistParser(masterPlaylist).parse(playlistUri, inputStream);
+        (HlsMediaPlaylist)
+            new HlsPlaylistParser(masterPlaylist, /* previousMediaPlaylist= */ null)
+                .parse(playlistUri, inputStream);
    assertThat(playlistWithInheritance.hasIndependentSegments).isTrue();
  }
@@ -1187,7 +1277,9 @@ public class HlsMediaPlaylistParserTest {
            variableDefinitions,
            /* sessionKeyDrmInitData= */ Collections.emptyList());
    HlsMediaPlaylist playlist =
-        (HlsMediaPlaylist) new HlsPlaylistParser(masterPlaylist).parse(playlistUri, inputStream);
+        (HlsMediaPlaylist)
+            new HlsPlaylistParser(masterPlaylist, /* previousMediaPlaylist= */ null)
+                .parse(playlistUri, inputStream);
    for (int i = 1; i <= 4; i++) {
      assertThat(playlist.segments.get(i - 1).url).isEqualTo("long_path" + i + ".ts");
    }