diff --git a/packager/live_packager_test.cc b/packager/live_packager_test.cc
index b895da47f2..08a9357e8a 100644
--- a/packager/live_packager_test.cc
+++ b/packager/live_packager_test.cc
@@ -870,7 +870,7 @@ TEST_F(LivePackagerBaseTest, VerifyPrdDecryptReEncrypt) {
   }
 }
 
-TEST_F(LivePackagerBaseTest, EditListAfterRepackage) {
+TEST_F(LivePackagerBaseTest, MoovAfterRepackage) {
   std::vector<uint8_t> init_segment_buffer =
       ReadTestDataFile("encrypted/prd_data/init.mp4");
   ASSERT_FALSE(init_segment_buffer.empty());
@@ -900,6 +900,8 @@ TEST_F(LivePackagerBaseTest, EditListAfterRepackage) {
     const auto& act_track = act_moov.tracks[i];
     EXPECT_EQ(exp_track.edit.list.edits, act_track.edit.list.edits);
   }
+
+  EXPECT_EQ(exp_moov.extends.tracks, act_moov.extends.tracks);
 }
 
 TEST_F(LivePackagerBaseTest, EncryptionFailure) {
diff --git a/packager/media/base/stream_info.h b/packager/media/base/stream_info.h
index 3317dc6d78..7caf971dd3 100644
--- a/packager/media/base/stream_info.h
+++ b/packager/media/base/stream_info.h
@@ -107,6 +107,9 @@ class StreamInfo {
     return encryption_config_;
   }
   int64_t media_time() const { return media_time_; }
+  uint32_t get_default_sample_duration() const {
+    return default_sample_duration_;
+  }
 
   void set_duration(int64_t duration) { duration_ = duration; }
   void set_codec(Codec codec) { codec_ = codec; }
@@ -125,6 +128,9 @@ class StreamInfo {
     encryption_config_ = encryption_config;
   }
   void set_media_time(int64_t media_time) { media_time_ = media_time; }
+  void set_default_sample_duration(uint32_t duration) {
+    default_sample_duration_ = duration;
+  }
 
  private:
   // Whether the stream is Audio or Video.
@@ -148,9 +154,12 @@ class StreamInfo {
   // codebooks.
   std::vector<uint8_t> codec_config_;
 
-  // Optional data required for preserving edit lists when repackaging an
+  // Optional data required for preserving media time when repackaging an
   // init segment alone.
   int64_t media_time_ = 0;
+  // Optional data required for preserving default sample duration when repackaging an
+  // init segment alone.
+  uint32_t default_sample_duration_ = 0;
 
   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
   // generated copy constructor and assignment operator. Since the extra data is
diff --git a/packager/media/formats/mp4/mp4_media_parser.cc b/packager/media/formats/mp4/mp4_media_parser.cc
index 1ebf126678..73c5ffe6a2 100644
--- a/packager/media/formats/mp4/mp4_media_parser.cc
+++ b/packager/media/formats/mp4/mp4_media_parser.cc
@@ -595,6 +595,13 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
       if (edit_list.edits.size() == 1u) {
         streams.back()->set_media_time(edit_list.edits.front().media_time);
       }
+
+      for (const auto& trex : moov_->extends.tracks) {
+        if (trex.track_id == track->header.track_id) {
+          streams.back()->set_default_sample_duration(trex.default_sample_duration);
+          break;
+        }
+      }
     }
 
     if (samp_descr.type == kVideo) {
@@ -768,6 +775,13 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
         video_stream_info->set_media_time(edit_list.edits.front().media_time);
       }
 
+      for (const auto& trex : moov_->extends.tracks) {
+        if (trex.track_id == track->header.track_id) {
+          video_stream_info->set_default_sample_duration(trex.default_sample_duration);
+          break;
+        }
+      }
+
       streams.push_back(video_stream_info);
     }
   }
diff --git a/packager/media/formats/mp4/mp4_muxer.cc b/packager/media/formats/mp4/mp4_muxer.cc
index e5c61bff1d..7d58b1de0b 100644
--- a/packager/media/formats/mp4/mp4_muxer.cc
+++ b/packager/media/formats/mp4/mp4_muxer.cc
@@ -264,6 +264,9 @@ Status MP4Muxer::DelayInitializeMuxer() {
     TrackExtends& trex = moov->extends.tracks[i];
     trex.track_id = trak.header.track_id;
     trex.default_sample_description_index = 1;
+    if (stream->get_default_sample_duration() != 0) {
+      trex.default_sample_duration = stream->get_default_sample_duration();
+    }
 
     bool generate_trak_result = false;
     switch (stream->stream_type()) {