MP4: Parse alternate_group and expose it in Format.metadata

Issue: androidx/media#2242
PiperOrigin-RevId: 740794206

RELEASENOTES.md

@@ -11,6 +11,9 @@
         variable bitrate metadata when falling back to constant bitrate seeking
         due to `FLAG_ENABLE_CONSTANT_BITRATE_SEEKING(_ALWAYS)`
         ([#2194](https://github.com/androidx/media/issues/2194)).
+    *   MP4: Parse `alternate_group` from the `tkhd` box and expose it as an
+        `Mp4AlternateGroupData` entry in each track's `Format.metadata`
+        ([#2242](https://github.com/androidx/media/issues/2242)).
 *   DataSource:
 *   Audio:
     *   Allow constant power upmixing/downmixing in DefaultAudioMixer.

libraries/container/src/main/java/androidx/media3/container/Mp4AlternateGroupData.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package androidx.media3.container;
+
+import androidx.annotation.Nullable;
+import androidx.media3.common.Metadata;
+import androidx.media3.common.util.UnstableApi;
+
+/** Stores MP4 {@code alternate_group} info parsed from a {@code tkhd} box. */
+@UnstableApi
+public final class Mp4AlternateGroupData implements Metadata.Entry {
+
+  public final int alternateGroup;
+
+  public Mp4AlternateGroupData(int alternateGroup) {
+    this.alternateGroup = alternateGroup;
+  }
+
+  @Override
+  public boolean equals(@Nullable Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (!(obj instanceof Mp4AlternateGroupData)) {
+      return false;
+    }
+
+    Mp4AlternateGroupData other = (Mp4AlternateGroupData) obj;
+    return alternateGroup == other.alternateGroup;
+  }
+
+  @Override
+  public int hashCode() {
+    return alternateGroup;
+  }
+
+  @Override
+  public String toString() {
+    return "Mp4AlternateGroup: " + alternateGroup;
+  }
+}

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/BoxParser.java

@@ -37,6 +37,7 @@ import androidx.media3.common.util.ParsableByteArray;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
 import androidx.media3.container.DolbyVisionConfig;
+import androidx.media3.container.Mp4AlternateGroupData;
 import androidx.media3.container.Mp4Box;
 import androidx.media3.container.Mp4Box.LeafBox;
 import androidx.media3.container.Mp4LocationData;
@@ -380,16 +381,33 @@ public final class BoxParser {
         }
       }
     }
-    return stsdData.format == null
+    if (stsdData.format == null) {
-        ? null
+      return null;
-        : new Track(
+    }
+    Format format;
+    if (tkhdData.alternateGroup != 0) {
+      Mp4AlternateGroupData alternateGroupEntry =
+          new Mp4AlternateGroupData(tkhdData.alternateGroup);
+      format =
+          stsdData
+              .format
+              .buildUpon()
+              .setMetadata(
+                  stsdData.format.metadata != null
+                      ? stsdData.format.metadata.copyWithAppendedEntries(alternateGroupEntry)
+                      : new Metadata(alternateGroupEntry))
+              .build();
+    } else {
+      format = stsdData.format;
+    }
+    return new Track(
         tkhdData.id,
         trackType,
         mdhdData.timescale,
         movieTimescale,
         durationUs,
         mdhdData.mediaDurationUs,
-            stsdData.format,
+        format,
         stsdData.requiredSampleTransformation,
         stsdData.trackEncryptionBoxes,
         stsdData.nalUnitLengthFieldLength,
@@ -913,7 +931,9 @@ public final class BoxParser {
       }
     }
 
-    tkhd.skipBytes(16);
+    tkhd.skipBytes(10);
+    int alternateGroup = tkhd.readUnsignedShort();
+    tkhd.skipBytes(4);
     int a00 = tkhd.readInt();
     int a01 = tkhd.readInt();
     tkhd.skipBytes(4);
@@ -933,7 +953,7 @@ public final class BoxParser {
       rotationDegrees = 0;
     }
 
-    return new TkhdData(trackId, duration, rotationDegrees);
+    return new TkhdData(trackId, duration, alternateGroup, rotationDegrees);
   }
 
   /**
@@ -2543,11 +2563,13 @@ public final class BoxParser {
 
     private final int id;
     private final long duration;
+    private final int alternateGroup;
     private final int rotationDegrees;
 
-    public TkhdData(int id, long duration, int rotationDegrees) {
+    public TkhdData(int id, long duration, int alternateGroup, int rotationDegrees) {
       this.id = id;
       this.duration = duration;
+      this.alternateGroup = alternateGroup;
       this.rotationDegrees = rotationDegrees;
     }
   }

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/MetadataUtil.java

@@ -84,13 +84,22 @@ import com.google.common.collect.ImmutableList;
 
   private MetadataUtil() {}
 
-  /** Updates a {@link Format.Builder} to include metadata from the provided sources. */
+  /**
+   * Updates a {@link Format.Builder} to include metadata from the provided sources.
+   *
+   * @param trackType The {@link C.TrackType} of the track.
+   * @param mdtaMetadata The {@link Metadata} from the {@code mdta} box if present, otherwise null.
+   * @param formatBuilder A {@link Format.Builder} to append the metadata too.
+   * @param existingMetadata The {@link Format#metadata} from {@code formatBuilder}.
+   * @param additionalMetadata Additional metadata to append.
+   */
   public static void setFormatMetadata(
-      int trackType,
+      @C.TrackType int trackType,
       @Nullable Metadata mdtaMetadata,
       Format.Builder formatBuilder,
+      @Nullable Metadata existingMetadata,
       @NullableType Metadata... additionalMetadata) {
-    Metadata formatMetadata = new Metadata();
+    Metadata formatMetadata = existingMetadata != null ? existingMetadata : new Metadata();
 
     if (mdtaMetadata != null) {
       for (int i = 0; i < mdtaMetadata.length(); i++) {

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/Mp4Extractor.java

@@ -775,6 +775,7 @@ public final class Mp4Extractor implements Extractor, SeekMap {
           track.type,
           mdtaMetadata,
           formatBuilder,
+          track.format.metadata,
           slowMotionMetadataEntries.isEmpty() ? null : new Metadata(slowMotionMetadataEntries),
           udtaMetadata,
           mvhdMetadata);

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.0.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.1.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.2.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.3.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.reading_within_gop_sample_dependencies.0.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.reading_within_gop_sample_dependencies.1.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.reading_within_gop_sample_dependencies.2.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.reading_within_gop_sample_dependencies.3.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/bt601.mov.unknown_length.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], Mp4Timestamp: creation time=3790610215, modification time=3790610215, timescale=30000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.0.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.1.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.2.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.3.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4.unknown_length.dump

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample.mp4_with_flag_read_auxiliary_tracks

@@ -162,7 +162,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
-    metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+    metadata = entries=[Mp4AlternateGroup: 1, TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
     initializationData:
       data = length 2, hash 5F7
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.0.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.1.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 96000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.2.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 192000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.3.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 256000
     flags = 536870913

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 96000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 192000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 256000
     flags = 536870913

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3.mp4.unknown_length.dump

@@ -20,7 +20,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3664419241, modification time=3664419241, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.0.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.1.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 96000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.2.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 192000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.3.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 256000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 96000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 192000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 256000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac3_fragmented.mp4.unknown_length.dump

@@ -19,6 +19,7 @@ track 0:
     channelCount = 6
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.0.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.1.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.2.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.3.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4.mp4.unknown_length.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3661132875, modification time=3661132875, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.0.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.1.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 240000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.2.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 480000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.3.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 720000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 240000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 480000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 720000
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_fragmented.mp4.unknown_length.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 2
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.0.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.1.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.2.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.3.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4.mp4.unknown_length.dump

@@ -18,7 +18,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
-    metadata = entries=[Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
+    metadata = entries=[Mp4AlternateGroup: 2, Mp4Timestamp: creation time=3785281997, modification time=3785281997, timescale=600]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.0.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.1.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.2.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.3.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 426666
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_ac4_level4_fragmented.mp4.unknown_length.dump

@@ -17,6 +17,7 @@ track 0:
     channelCount = 21
     sampleRate = 48000
     language = und
+    metadata = entries=[Mp4AlternateGroup: 2]
   sample 0:
     time = 0
     flags = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented.mp4.0.dump

@@ -153,6 +153,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -153,6 +153,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -153,6 +153,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented.mp4.unknown_length.dump

@@ -153,6 +153,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.0.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.1.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.2.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.3.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0:

libraries/test_data/src/test/assets/extractordumps/mp4/sample_fragmented_large_bitrates.mp4.unknown_length.dump

@@ -161,6 +161,7 @@ track 1:
     channelCount = 1
     sampleRate = 44100
     language = und
+    metadata = entries=[Mp4AlternateGroup: 1]
     initializationData:
       data = length 5, hash 2B7623A
   sample 0: