diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/e2etest/MkvPlaybackTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/e2etest/MkvPlaybackTest.java
index f8cf3fea282..99ed83b7711 100644
--- a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/e2etest/MkvPlaybackTest.java
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/e2etest/MkvPlaybackTest.java
@@ -47,13 +47,16 @@ public static ImmutableList<String> mediaSamples() {
         "sample_with_htc_rotation_track_name.mkv",
         "sample_with_pgs_subtitles.mkv",
         "sample_with_ssa_subtitles.mkv",
+        "sample_with_zlib_ass_subtitles.mkv",
         "sample_with_null_terminated_ssa_subtitles.mkv",
         "sample_with_overlapping_ssa_subtitles.mkv",
         "sample_with_srt.mkv",
         "sample_with_null_terminated_srt.mkv",
+        "sample_with_zlib_null_terminated_srt.mkv",
         "sample_with_overlapping_srt.mkv",
         "sample_with_vtt_subtitles.mkv",
         "sample_with_null_terminated_vtt_subtitles.mkv",
+        "sample_with_zlib_null_terminated_vtt_subtitles.mkv",
         "sample_with_vobsub.mkv");
   }
 
diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java b/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
index 4f4a08a1a6c..c58348e326b 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
@@ -84,6 +84,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.UUID;
+import java.util.zip.Inflater;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.RequiresNonNull;
@@ -463,6 +464,7 @@ public static ExtractorsFactory newFactory(SubtitleParser.Factory subtitleParser
   private final ParsableByteArray seekEntryIdBytes;
   private final ParsableByteArray sampleStrippedBytes;
   private final ParsableByteArray subtitleSample;
+  private final ParsableByteArray inflatedSubtitleSample;
   private final ParsableByteArray encryptionInitializationVector;
   private final ParsableByteArray encryptionSubsampleData;
   private final ParsableByteArray supplementalData;
@@ -476,6 +478,9 @@ public static ExtractorsFactory newFactory(SubtitleParser.Factory subtitleParser
   private boolean isWebm;
   private boolean pendingEndTracks;
 
+  // Inflater for zlib compressed tracks
+  @Nullable private Inflater inflater;
+
   // The chapter corresponding to the current EditionEntry element, or null.
   @Nullable private ChapterEntry currentChapter;
 
@@ -591,6 +596,7 @@ public MatroskaExtractor(SubtitleParser.Factory subtitleParserFactory, @Flags in
     nalLength = new ParsableByteArray(4);
     sampleStrippedBytes = new ParsableByteArray();
     subtitleSample = new ParsableByteArray();
+    inflatedSubtitleSample = new ParsableByteArray();
     encryptionInitializationVector = new ParsableByteArray(ENCRYPTION_IV_SIZE);
     encryptionSubsampleData = new ParsableByteArray();
     supplementalData = new ParsableByteArray();
@@ -863,6 +869,9 @@ protected void startMasterElement(int id, long contentPosition, long contentSize
       case ID_CONTENT_ENCODING:
         // TODO: check and fail if more than one content encoding is present.
         break;
+      case ID_CONTENT_COMPRESSION:
+        getCurrentTrack(id).hasContentCompression = true;
+        break;
       case ID_CONTENT_ENCRYPTION:
         getCurrentTrack(id).hasContentEncryption = true;
         break;
@@ -1256,8 +1265,8 @@ protected void integerElement(int id, long value) throws ParserException {
         }
         break;
       case ID_CONTENT_COMPRESSION_ALGORITHM:
-        // This extractor only supports header stripping.
-        if (value != 3) {
+        // This extractor only supports header stripping and zlib compressed text tracks.
+        if (value != 3 && (value != 0 || getCurrentTrack(id).type != C.TRACK_TYPE_TEXT)) {
           throw ParserException.createForMalformedContainer(
               "ContentCompAlgo " + value + " not supported", /* cause= */ null);
         }
@@ -1834,13 +1843,13 @@ private void readScratch(ExtractorInput input, int requiredLength) throws IOExce
   private int writeSampleData(ExtractorInput input, Track track, int size, boolean isBlockGroup)
       throws IOException {
     if (CODEC_ID_SUBRIP.equals(track.codecId)) {
-      writeSubtitleSampleData(input, SUBRIP_PREFIX, size);
+      writeSubtitleSampleData(input, SUBRIP_PREFIX, size, track.hasContentCompression);
       return finishWriteSampleData();
     } else if (CODEC_ID_ASS.equals(track.codecId) || CODEC_ID_SSA.equals(track.codecId)) {
-      writeSubtitleSampleData(input, SSA_PREFIX, size);
+      writeSubtitleSampleData(input, SSA_PREFIX, size, track.hasContentCompression);
       return finishWriteSampleData();
     } else if (CODEC_ID_VTT.equals(track.codecId)) {
-      writeSubtitleSampleData(input, VTT_PREFIX, size);
+      writeSubtitleSampleData(input, VTT_PREFIX, size, track.hasContentCompression);
       return finishWriteSampleData();
     }
 
@@ -2055,7 +2064,8 @@ private void resetWriteSampleData() {
     sampleStrippedBytes.reset(/* limit= */ 0);
   }
 
-  private void writeSubtitleSampleData(ExtractorInput input, byte[] samplePrefix, int size)
+  private void writeSubtitleSampleData(
+      ExtractorInput input, byte[] samplePrefix, int size, boolean hasContentCompression)
       throws IOException {
     int sizeWithPrefix = samplePrefix.length + size;
     if (subtitleSample.capacity() < sizeWithPrefix) {
@@ -2066,6 +2076,25 @@ private void writeSubtitleSampleData(ExtractorInput input, byte[] samplePrefix,
       System.arraycopy(samplePrefix, 0, subtitleSample.getData(), 0, samplePrefix.length);
     }
     input.readFully(subtitleSample.getData(), samplePrefix.length, size);
+
+    if (hasContentCompression) {
+      if (inflater == null) {
+        inflater = new Inflater();
+      }
+      subtitleSample.setPosition(samplePrefix.length);
+      subtitleSample.setLimit(sizeWithPrefix);
+      if (Util.maybeInflate(subtitleSample, inflatedSubtitleSample, inflater)) {
+        sizeWithPrefix = samplePrefix.length + inflatedSubtitleSample.limit();
+        subtitleSample.ensureCapacity(sizeWithPrefix);
+        System.arraycopy(
+            inflatedSubtitleSample.getData(),
+            0,
+            subtitleSample.getData(),
+            samplePrefix.length,
+            inflatedSubtitleSample.limit());
+      }
+    }
+
     subtitleSample.setPosition(0);
     subtitleSample.setLimit(sizeWithPrefix);
     // Defer writing the data to the track output. We need to modify the sample data by setting
@@ -2359,6 +2388,7 @@ protected static final class Track {
     public int defaultSampleDurationNs;
     public int maxBlockAdditionId;
     private int blockAddIdType;
+    public boolean hasContentCompression;
     public boolean hasContentEncryption;
     public byte @MonotonicNonNull [] sampleStrippedBytes;
     public TrackOutput.@MonotonicNonNull CryptoData cryptoData;
diff --git a/libraries/extractor/src/test/java/androidx/media3/extractor/mkv/MatroskaExtractorTest.java b/libraries/extractor/src/test/java/androidx/media3/extractor/mkv/MatroskaExtractorTest.java
index 756b9b6fdb2..f24e14f3acc 100644
--- a/libraries/extractor/src/test/java/androidx/media3/extractor/mkv/MatroskaExtractorTest.java
+++ b/libraries/extractor/src/test/java/androidx/media3/extractor/mkv/MatroskaExtractorTest.java
@@ -92,6 +92,19 @@ public void mkvSample_withNullTerminatedSubripSubtitles() throws Exception {
         simulationConfig);
   }
 
+  @Test
+  // TODO: b/507050745 - Suppressed due to failure with subtitlesParsedDuringExtraction=true on SDK
+  // >= 32.
+  @Config(maxSdk = 31)
+  public void mkvSample_withZlibNullTerminatedSubripSubtitles() throws Exception {
+    ExtractorAsserts.assertBehavior(
+        getExtractorFactory(subtitlesParsedDuringExtraction),
+        "media/mkv/sample_with_zlib_null_terminated_srt.mkv",
+        getAssertionConfigWithPrefix(
+            "media/mkv/sample_with_zlib_null_terminated_srt.mkv", subtitlesParsedDuringExtraction),
+        simulationConfig);
+  }
+
   @Test
   // TODO: b/507050745 - Suppressed due to failure with subtitlesParsedDuringExtraction=true on SDK
   // >= 32.
@@ -143,6 +156,19 @@ public void mkvSample_withAssSubtitles() throws Exception {
         simulationConfig);
   }
 
+  @Test
+  // TODO: b/507050745 - Suppressed due to failure with subtitlesParsedDuringExtraction=true on SDK
+  // >= 32.
+  @Config(maxSdk = 31)
+  public void mkvSample_withZlibAssSubtitles() throws Exception {
+    ExtractorAsserts.assertBehavior(
+        getExtractorFactory(subtitlesParsedDuringExtraction),
+        "media/mkv/sample_with_zlib_ass_subtitles.mkv",
+        getAssertionConfigWithPrefix(
+            "media/mkv/sample_with_zlib_ass_subtitles.mkv", subtitlesParsedDuringExtraction),
+        simulationConfig);
+  }
+
   // https://github.com/google/ExoPlayer/pull/8265
   @Test
   // TODO: b/507050745 - Suppressed due to failure with subtitlesParsedDuringExtraction=true on SDK
@@ -198,6 +224,20 @@ public void mkvSample_withNullTerminatedVttSubtitles() throws Exception {
         simulationConfig);
   }
 
+  @Test
+  // TODO: b/507050745 - Suppressed due to failure with subtitlesParsedDuringExtraction=true on SDK
+  // >= 32.
+  @Config(maxSdk = 31)
+  public void mkvSample_withZlibNullTerminatedVttSubtitles() throws Exception {
+    ExtractorAsserts.assertBehavior(
+        getExtractorFactory(subtitlesParsedDuringExtraction),
+        "media/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv",
+        getAssertionConfigWithPrefix(
+            "media/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv",
+            subtitlesParsedDuringExtraction),
+        simulationConfig);
+  }
+
   @Test
   public void mkvSample_withVorbisAudio() throws Exception {
     ExtractorAsserts.assertBehavior(
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.0.dump
new file mode 100644
index 00000000000..776114637cc
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.0.dump
@@ -0,0 +1,291 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 81
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 81, hash F61A8B12
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.1.dump
new file mode 100644
index 00000000000..776114637cc
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.1.dump
@@ -0,0 +1,291 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 81
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 81, hash F61A8B12
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.2.dump
new file mode 100644
index 00000000000..776114637cc
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.2.dump
@@ -0,0 +1,291 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 81
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 81, hash F61A8B12
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.3.dump
new file mode 100644
index 00000000000..776114637cc
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.3.dump
@@ -0,0 +1,291 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 81
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 81, hash F61A8B12
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump
new file mode 100644
index 00000000000..776114637cc
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump
@@ -0,0 +1,291 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 81
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 81, hash F61A8B12
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.0.dump
new file mode 100644
index 00000000000..18cb01954a0
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.0.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 49
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 49, hash DE7F89EF
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.1.dump
new file mode 100644
index 00000000000..18cb01954a0
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.1.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 49
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 49, hash DE7F89EF
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.2.dump
new file mode 100644
index 00000000000..18cb01954a0
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.2.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 49
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 49, hash DE7F89EF
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.3.dump
new file mode 100644
index 00000000000..18cb01954a0
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.3.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 49
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 49, hash DE7F89EF
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump
new file mode 100644
index 00000000000..18cb01954a0
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 49
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 49, hash DE7F89EF
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump
new file mode 100644
index 00000000000..3e37950b6c3
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump
@@ -0,0 +1,288 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 55
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 55, hash F96B22E6
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump
new file mode 100644
index 00000000000..3e37950b6c3
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump
@@ -0,0 +1,288 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 55
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 55, hash F96B22E6
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump
new file mode 100644
index 00000000000..3e37950b6c3
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump
@@ -0,0 +1,288 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 55
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 55, hash F96B22E6
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump
new file mode 100644
index 00000000000..3e37950b6c3
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump
@@ -0,0 +1,288 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 55
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 55, hash F96B22E6
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump
new file mode 100644
index 00000000000..3e37950b6c3
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump
@@ -0,0 +1,288 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 55
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 55, hash F96B22E6
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.0.dump
new file mode 100644
index 00000000000..288ea5a2cb7
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.0.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1291
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1291, hash 7F76D24B
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.1.dump
new file mode 100644
index 00000000000..288ea5a2cb7
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.1.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1291
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1291, hash 7F76D24B
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.2.dump
new file mode 100644
index 00000000000..288ea5a2cb7
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.2.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1291
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1291, hash 7F76D24B
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.3.dump
new file mode 100644
index 00000000000..288ea5a2cb7
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.3.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1291
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1291, hash 7F76D24B
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump
new file mode 100644
index 00000000000..288ea5a2cb7
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_ass_subtitles.mkv.unknown_length.dump
@@ -0,0 +1,292 @@
+seekMap:
+  isSeekable = true
+  duration = 1139000
+  getPosition(0) = [[timeUs=67000, position=6131]]
+  getPosition(1) = [[timeUs=67000, position=6131]]
+  getPosition(569500) = [[timeUs=67000, position=6131]]
+  getPosition(1139000) = [[timeUs=67000, position=6131]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=67000]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 67000
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 134000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 100000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 267000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 200000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 167000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 234000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 400000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 334000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 300000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 367000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 500000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 467000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 434000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 634000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 567000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 534000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 600000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 767000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 700000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 667000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 734000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 900000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 834000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 800000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 867000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 1034000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 967000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 934000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 1000000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 129000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 163829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 198659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 233489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 268319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 303149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 337979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 372809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 408000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 442829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 477659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 512489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 547319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 582149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 616979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 651809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 687000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 721829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 756659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 791489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 826319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 861149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 895979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 930809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 965000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 999829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 1034659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1069489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1104319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1291
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/x-ssa
+    selectionFlags = [default]
+    language = und
+    initializationData:
+      data = length 90, hash A5E21974
+      data = length 470, hash 40E7D996
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1291, hash 7F76D24B
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.0.dump
new file mode 100644
index 00000000000..ccb3613d112
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.0.dump
@@ -0,0 +1,293 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 994
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 994, hash 6AA26024
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.1.dump
new file mode 100644
index 00000000000..ccb3613d112
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.1.dump
@@ -0,0 +1,293 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 994
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 994, hash 6AA26024
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.2.dump
new file mode 100644
index 00000000000..ccb3613d112
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.2.dump
@@ -0,0 +1,293 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 994
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 994, hash 6AA26024
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.3.dump
new file mode 100644
index 00000000000..ccb3613d112
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.3.dump
@@ -0,0 +1,293 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 994
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 994, hash 6AA26024
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump
new file mode 100644
index 00000000000..ccb3613d112
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_srt.mkv.unknown_length.dump
@@ -0,0 +1,293 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=978]]
+  getPosition(1) = [[timeUs=0, position=978]]
+  getPosition(617000) = [[timeUs=0, position=978]]
+  getPosition(1234000) = [[timeUs=0, position=978]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 97000
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131000
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166000
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201000
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236000
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270000
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 306000
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 376000
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410000
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445000
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 514000
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 550000
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 585000
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654000
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 690000
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724000
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759000
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 793000
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 829000
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 864000
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932000
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 968000
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002000
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037000
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 994
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = application/x-subrip
+    selectionFlags = [default]
+    language = en
+    label = Subs Label
+    labels:
+      lang = en
+      value = Subs Label
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 994, hash 6AA26024
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump
new file mode 100644
index 00000000000..82abee72c75
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.0.dump
@@ -0,0 +1,289 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1161
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1161, hash 1A73F62
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump
new file mode 100644
index 00000000000..82abee72c75
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.1.dump
@@ -0,0 +1,289 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1161
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1161, hash 1A73F62
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump
new file mode 100644
index 00000000000..82abee72c75
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.2.dump
@@ -0,0 +1,289 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1161
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1161, hash 1A73F62
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump
new file mode 100644
index 00000000000..82abee72c75
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.3.dump
@@ -0,0 +1,289 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1161
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1161, hash 1A73F62
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump
new file mode 100644
index 00000000000..82abee72c75
--- /dev/null
+++ b/libraries/test_data/src/test/assets/extractordumps/mkv_subtitle_transcoding/sample_with_zlib_null_terminated_vtt_subtitles.mkv.unknown_length.dump
@@ -0,0 +1,289 @@
+seekMap:
+  isSeekable = true
+  duration = 1234000
+  getPosition(0) = [[timeUs=0, position=5679]]
+  getPosition(1) = [[timeUs=0, position=5679]]
+  getPosition(617000) = [[timeUs=0, position=5679]]
+  getPosition(1234000) = [[timeUs=0, position=5679]]
+numberOfTracks = 3
+track 1:
+  total output bytes = 89502
+  sample count = 30
+  format 0:
+    id = 1
+    containerMimeType = video/x-matroska
+    sampleMimeType = video/avc
+    codecs = avc1.640034
+    width = 1080
+    height = 720
+    colorInfo:
+      lumaBitdepth = 8
+      chromaBitdepth = 8
+    selectionFlags = [default]
+    language = und
+    metadata = entries=[ThumbnailMetadata: presentationTimeUs=0]
+    initializationData:
+      data = length 30, hash F6F3D010
+      data = length 10, hash 7A0D0F2B
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 36477, hash F0F36CFE
+  sample 1:
+    time = 67000
+    flags = 0
+    data = length 5341, hash 40B85E2
+  sample 2:
+    time = 33000
+    flags = 0
+    data = length 596, hash 357B4D92
+  sample 3:
+    time = 200000
+    flags = 0
+    data = length 7704, hash A39EDA06
+  sample 4:
+    time = 133000
+    flags = 0
+    data = length 989, hash 2813C72D
+  sample 5:
+    time = 100000
+    flags = 0
+    data = length 721, hash C50D1C73
+  sample 6:
+    time = 167000
+    flags = 0
+    data = length 519, hash 65FE1911
+  sample 7:
+    time = 333000
+    flags = 0
+    data = length 6160, hash E1CAC0EC
+  sample 8:
+    time = 267000
+    flags = 0
+    data = length 953, hash 7160C661
+  sample 9:
+    time = 233000
+    flags = 0
+    data = length 620, hash 7A7AE07C
+  sample 10:
+    time = 300000
+    flags = 0
+    data = length 405, hash 5CC7F4E7
+  sample 11:
+    time = 433000
+    flags = 0
+    data = length 4852, hash 9DB6979D
+  sample 12:
+    time = 400000
+    flags = 0
+    data = length 547, hash E31A6979
+  sample 13:
+    time = 367000
+    flags = 0
+    data = length 570, hash FEC40D00
+  sample 14:
+    time = 567000
+    flags = 0
+    data = length 5525, hash 7C478F7E
+  sample 15:
+    time = 500000
+    flags = 0
+    data = length 1082, hash DA07059A
+  sample 16:
+    time = 467000
+    flags = 0
+    data = length 807, hash 93478E6B
+  sample 17:
+    time = 533000
+    flags = 0
+    data = length 744, hash 9A8E6026
+  sample 18:
+    time = 700000
+    flags = 0
+    data = length 4732, hash C73B23C0
+  sample 19:
+    time = 633000
+    flags = 0
+    data = length 1004, hash 8A19A228
+  sample 20:
+    time = 600000
+    flags = 0
+    data = length 794, hash 8126022C
+  sample 21:
+    time = 667000
+    flags = 0
+    data = length 645, hash F08300E5
+  sample 22:
+    time = 833000
+    flags = 0
+    data = length 2684, hash 727FE378
+  sample 23:
+    time = 767000
+    flags = 0
+    data = length 787, hash 419A7821
+  sample 24:
+    time = 733000
+    flags = 0
+    data = length 649, hash 5C159346
+  sample 25:
+    time = 800000
+    flags = 0
+    data = length 509, hash F912D655
+  sample 26:
+    time = 967000
+    flags = 0
+    data = length 1226, hash 29815C21
+  sample 27:
+    time = 900000
+    flags = 0
+    data = length 898, hash D997AD0A
+  sample 28:
+    time = 867000
+    flags = 0
+    data = length 476, hash A0423645
+  sample 29:
+    time = 933000
+    flags = 0
+    data = length 486, hash DDF32CBB
+track 2:
+  total output bytes = 12120
+  sample count = 29
+  format 0:
+    id = 2
+    containerMimeType = video/x-matroska
+    sampleMimeType = audio/ac3
+    channelCount = 1
+    sampleRate = 44100
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 62000
+    flags = 1
+    data = length 416, hash 211F2286
+  sample 1:
+    time = 96829
+    flags = 1
+    data = length 418, hash 77425A86
+  sample 2:
+    time = 131659
+    flags = 1
+    data = length 418, hash A0FE5CA1
+  sample 3:
+    time = 166489
+    flags = 1
+    data = length 418, hash 2309B066
+  sample 4:
+    time = 201319
+    flags = 1
+    data = length 418, hash 928A653B
+  sample 5:
+    time = 236149
+    flags = 1
+    data = length 418, hash 3422F0CB
+  sample 6:
+    time = 270979
+    flags = 1
+    data = length 418, hash EFF43D5B
+  sample 7:
+    time = 305809
+    flags = 1
+    data = length 418, hash FC8093C7
+  sample 8:
+    time = 341000
+    flags = 1
+    data = length 418, hash CCC08A16
+  sample 9:
+    time = 375829
+    flags = 1
+    data = length 418, hash 2A6EE863
+  sample 10:
+    time = 410659
+    flags = 1
+    data = length 418, hash D69A9251
+  sample 11:
+    time = 445489
+    flags = 1
+    data = length 418, hash BCFB758D
+  sample 12:
+    time = 480319
+    flags = 1
+    data = length 418, hash 11B66799
+  sample 13:
+    time = 515149
+    flags = 1
+    data = length 418, hash C824D392
+  sample 14:
+    time = 549979
+    flags = 1
+    data = length 418, hash C167D872
+  sample 15:
+    time = 584809
+    flags = 1
+    data = length 418, hash 4221C855
+  sample 16:
+    time = 620000
+    flags = 1
+    data = length 418, hash 4D4FF934
+  sample 17:
+    time = 654829
+    flags = 1
+    data = length 418, hash 984AA025
+  sample 18:
+    time = 689659
+    flags = 1
+    data = length 418, hash BB788B46
+  sample 19:
+    time = 724489
+    flags = 1
+    data = length 418, hash 9EFBFD97
+  sample 20:
+    time = 759319
+    flags = 1
+    data = length 418, hash DF1A460C
+  sample 21:
+    time = 794149
+    flags = 1
+    data = length 418, hash 2BDB56A
+  sample 22:
+    time = 828979
+    flags = 1
+    data = length 418, hash CA230060
+  sample 23:
+    time = 863809
+    flags = 1
+    data = length 418, hash D2F19F41
+  sample 24:
+    time = 898000
+    flags = 1
+    data = length 418, hash AF392D79
+  sample 25:
+    time = 932829
+    flags = 1
+    data = length 418, hash C5D7F2A3
+  sample 26:
+    time = 967659
+    flags = 1
+    data = length 418, hash 733A35AE
+  sample 27:
+    time = 1002489
+    flags = 1
+    data = length 418, hash DE46E5D3
+  sample 28:
+    time = 1037319
+    flags = 1
+    data = length 418, hash 56AB8D37
+track 3:
+  total output bytes = 1161
+  sample count = 1
+  format 0:
+    id = 3
+    containerMimeType = video/x-matroska
+    sampleMimeType = application/x-media3-cues
+    codecs = text/vtt
+    selectionFlags = [default]
+    language = und
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 1161, hash 1A73F62
+tracksEnded = true
diff --git a/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_ass_subtitles.mkv b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_ass_subtitles.mkv
new file mode 100644
index 00000000000..cd2e950f616
Binary files /dev/null and b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_ass_subtitles.mkv differ
diff --git a/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_srt.mkv b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_srt.mkv
new file mode 100644
index 00000000000..46b9d8bc637
Binary files /dev/null and b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_srt.mkv differ
diff --git a/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv
new file mode 100644
index 00000000000..28eaa974f0a
Binary files /dev/null and b/libraries/test_data/src/test/assets/media/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv differ
diff --git a/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_ass_subtitles.mkv.dump b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_ass_subtitles.mkv.dump
new file mode 100644
index 00000000000..1954b5f4bba
--- /dev/null
+++ b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_ass_subtitles.mkv.dump
@@ -0,0 +1,541 @@
+MediaCodecAdapter (media3.audio.ac3):
+  inputBuffers:
+    count = 30
+    input buffer #0:
+      timeUs = 1000000129000
+      contents = length 416, hash 211F2286
+    input buffer #1:
+      timeUs = 1000000163829
+      contents = length 418, hash 77425A86
+    input buffer #2:
+      timeUs = 1000000198659
+      contents = length 418, hash A0FE5CA1
+    input buffer #3:
+      timeUs = 1000000233489
+      contents = length 418, hash 2309B066
+    input buffer #4:
+      timeUs = 1000000268319
+      contents = length 418, hash 928A653B
+    input buffer #5:
+      timeUs = 1000000303149
+      contents = length 418, hash 3422F0CB
+    input buffer #6:
+      timeUs = 1000000337979
+      contents = length 418, hash EFF43D5B
+    input buffer #7:
+      timeUs = 1000000372809
+      contents = length 418, hash FC8093C7
+    input buffer #8:
+      timeUs = 1000000408000
+      contents = length 418, hash CCC08A16
+    input buffer #9:
+      timeUs = 1000000442829
+      contents = length 418, hash 2A6EE863
+    input buffer #10:
+      timeUs = 1000000477659
+      contents = length 418, hash D69A9251
+    input buffer #11:
+      timeUs = 1000000512489
+      contents = length 418, hash BCFB758D
+    input buffer #12:
+      timeUs = 1000000547319
+      contents = length 418, hash 11B66799
+    input buffer #13:
+      timeUs = 1000000582149
+      contents = length 418, hash C824D392
+    input buffer #14:
+      timeUs = 1000000616979
+      contents = length 418, hash C167D872
+    input buffer #15:
+      timeUs = 1000000651809
+      contents = length 418, hash 4221C855
+    input buffer #16:
+      timeUs = 1000000687000
+      contents = length 418, hash 4D4FF934
+    input buffer #17:
+      timeUs = 1000000721829
+      contents = length 418, hash 984AA025
+    input buffer #18:
+      timeUs = 1000000756659
+      contents = length 418, hash BB788B46
+    input buffer #19:
+      timeUs = 1000000791489
+      contents = length 418, hash 9EFBFD97
+    input buffer #20:
+      timeUs = 1000000826319
+      contents = length 418, hash DF1A460C
+    input buffer #21:
+      timeUs = 1000000861149
+      contents = length 418, hash 2BDB56A
+    input buffer #22:
+      timeUs = 1000000895979
+      contents = length 418, hash CA230060
+    input buffer #23:
+      timeUs = 1000000930809
+      contents = length 418, hash D2F19F41
+    input buffer #24:
+      timeUs = 1000000965000
+      contents = length 418, hash AF392D79
+    input buffer #25:
+      timeUs = 1000000999829
+      contents = length 418, hash C5D7F2A3
+    input buffer #26:
+      timeUs = 1000001034659
+      contents = length 418, hash 733A35AE
+    input buffer #27:
+      timeUs = 1000001069489
+      contents = length 418, hash DE46E5D3
+    input buffer #28:
+      timeUs = 1000001104319
+      contents = length 418, hash 56AB8D37
+    input buffer #29:
+      timeUs = 0
+      flags = 4
+      contents = length 0, hash 1
+  outputBuffers:
+    count = 29
+    output buffer #0:
+      timeUs = 1000000129000
+      size = 0
+      rendered = false
+    output buffer #1:
+      timeUs = 1000000163829
+      size = 0
+      rendered = false
+    output buffer #2:
+      timeUs = 1000000198659
+      size = 0
+      rendered = false
+    output buffer #3:
+      timeUs = 1000000233489
+      size = 0
+      rendered = false
+    output buffer #4:
+      timeUs = 1000000268319
+      size = 0
+      rendered = false
+    output buffer #5:
+      timeUs = 1000000303149
+      size = 0
+      rendered = false
+    output buffer #6:
+      timeUs = 1000000337979
+      size = 0
+      rendered = false
+    output buffer #7:
+      timeUs = 1000000372809
+      size = 0
+      rendered = false
+    output buffer #8:
+      timeUs = 1000000408000
+      size = 0
+      rendered = false
+    output buffer #9:
+      timeUs = 1000000442829
+      size = 0
+      rendered = false
+    output buffer #10:
+      timeUs = 1000000477659
+      size = 0
+      rendered = false
+    output buffer #11:
+      timeUs = 1000000512489
+      size = 0
+      rendered = false
+    output buffer #12:
+      timeUs = 1000000547319
+      size = 0
+      rendered = false
+    output buffer #13:
+      timeUs = 1000000582149
+      size = 0
+      rendered = false
+    output buffer #14:
+      timeUs = 1000000616979
+      size = 0
+      rendered = false
+    output buffer #15:
+      timeUs = 1000000651809
+      size = 0
+      rendered = false
+    output buffer #16:
+      timeUs = 1000000687000
+      size = 0
+      rendered = false
+    output buffer #17:
+      timeUs = 1000000721829
+      size = 0
+      rendered = false
+    output buffer #18:
+      timeUs = 1000000756659
+      size = 0
+      rendered = false
+    output buffer #19:
+      timeUs = 1000000791489
+      size = 0
+      rendered = false
+    output buffer #20:
+      timeUs = 1000000826319
+      size = 0
+      rendered = false
+    output buffer #21:
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+      size = 0
+      rendered = false
+    output buffer #22:
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+      size = 0
+      rendered = false
+    output buffer #23:
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+      size = 0
+      rendered = false
+    output buffer #24:
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+      size = 0
+      rendered = false
+    output buffer #25:
+      timeUs = 1000000999829
+      size = 0
+      rendered = false
+    output buffer #26:
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+      size = 0
+      rendered = false
+    output buffer #27:
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+      size = 0
+      rendered = false
+    output buffer #28:
+      timeUs = 1000001104319
+      size = 0
+      rendered = false
+MediaCodecAdapter (media3.video.avc):
+  inputBuffers:
+    count = 31
+    input buffer #0:
+      timeUs = 1000000067000
+      contents = length 36477, hash F0F36CFE
+    input buffer #1:
+      timeUs = 1000000134000
+      contents = length 5341, hash 40B85E2
+    input buffer #2:
+      timeUs = 1000000100000
+      contents = length 596, hash 357B4D92
+    input buffer #3:
+      timeUs = 1000000267000
+      contents = length 7704, hash A39EDA06
+    input buffer #4:
+      timeUs = 1000000200000
+      contents = length 989, hash 2813C72D
+    input buffer #5:
+      timeUs = 1000000167000
+      contents = length 721, hash C50D1C73
+    input buffer #6:
+      timeUs = 1000000234000
+      contents = length 519, hash 65FE1911
+    input buffer #7:
+      timeUs = 1000000400000
+      contents = length 6160, hash E1CAC0EC
+    input buffer #8:
+      timeUs = 1000000334000
+      contents = length 953, hash 7160C661
+    input buffer #9:
+      timeUs = 1000000300000
+      contents = length 620, hash 7A7AE07C
+    input buffer #10:
+      timeUs = 1000000367000
+      contents = length 405, hash 5CC7F4E7
+    input buffer #11:
+      timeUs = 1000000500000
+      contents = length 4852, hash 9DB6979D
+    input buffer #12:
+      timeUs = 1000000467000
+      contents = length 547, hash E31A6979
+    input buffer #13:
+      timeUs = 1000000434000
+      contents = length 570, hash FEC40D00
+    input buffer #14:
+      timeUs = 1000000634000
+      contents = length 5525, hash 7C478F7E
+    input buffer #15:
+      timeUs = 1000000567000
+      contents = length 1082, hash DA07059A
+    input buffer #16:
+      timeUs = 1000000534000
+      contents = length 807, hash 93478E6B
+    input buffer #17:
+      timeUs = 1000000600000
+      contents = length 744, hash 9A8E6026
+    input buffer #18:
+      timeUs = 1000000767000
+      contents = length 4732, hash C73B23C0
+    input buffer #19:
+      timeUs = 1000000700000
+      contents = length 1004, hash 8A19A228
+    input buffer #20:
+      timeUs = 1000000667000
+      contents = length 794, hash 8126022C
+    input buffer #21:
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+      contents = length 645, hash F08300E5
+    input buffer #22:
+      timeUs = 1000000900000
+      contents = length 2684, hash 727FE378
+    input buffer #23:
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+      contents = length 787, hash 419A7821
+    input buffer #24:
+      timeUs = 1000000800000
+      contents = length 649, hash 5C159346
+    input buffer #25:
+      timeUs = 1000000867000
+      contents = length 509, hash F912D655
+    input buffer #26:
+      timeUs = 1000001034000
+      contents = length 1226, hash 29815C21
+    input buffer #27:
+      timeUs = 1000000967000
+      contents = length 898, hash D997AD0A
+    input buffer #28:
+      timeUs = 1000000934000
+      contents = length 476, hash A0423645
+    input buffer #29:
+      timeUs = 1000001000000
+      contents = length 486, hash DDF32CBB
+    input buffer #30:
+      timeUs = 0
+      flags = 4
+      contents = length 0, hash 1
+  outputBuffers:
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+    output buffer #0:
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+      size = 36477
+      rendered = true
+    output buffer #1:
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+      rendered = true
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+      rendered = true
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+  Subtitle[1]:
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+      line = 0.95
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+      lineAnchor = 2
+      position = 0.5
+      positionAnchor = 1
+  Subtitle[2]:
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diff --git a/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_srt.mkv.dump b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_srt.mkv.dump
new file mode 100644
index 00000000000..7197e3abe55
--- /dev/null
+++ b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_srt.mkv.dump
@@ -0,0 +1,532 @@
+MediaCodecAdapter (media3.audio.ac3):
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+MediaCodecAdapter (media3.video.avc):
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diff --git a/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.dump b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.dump
new file mode 100644
index 00000000000..f9c87321687
--- /dev/null
+++ b/libraries/test_data/src/test/assets/playbackdumps/mkv/sample_with_zlib_null_terminated_vtt_subtitles.mkv.dump
@@ -0,0 +1,539 @@
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