fix: flag to indicate origin of header duration

packager/media/base/stream_info.h

@@ -110,6 +110,7 @@ class StreamInfo {
   uint32_t get_default_sample_duration() const {
     return default_sample_duration_;
   }
+  bool is_mehd_header_duration() const { return mehd_header_carryover_; };
 
   void set_duration(int64_t duration) { duration_ = duration; }
   void set_codec(Codec codec) { codec_ = codec; }
@@ -132,6 +133,10 @@ class StreamInfo {
     default_sample_duration_ = duration;
   }
 
+  void set_mehd_header_carryover(bool mehd_header_carryover) {
+    mehd_header_carryover_ = mehd_header_carryover;
+  }
+
  private:
   // Whether the stream is Audio or Video.
   StreamType stream_type_;
@@ -161,6 +166,10 @@ class StreamInfo {
   // repackaging an init segment alone.
   uint32_t default_sample_duration_ = 0;
 
+  // Flag to indicate whether the duration originated in the movie extends
+  // header and should carry over to the output segment.
+  bool mehd_header_carryover_ = false;
+
   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
   // generated copy constructor and assignment operator. Since the extra data is
   // typically small, the performance impact is minimal.

packager/media/formats/mp4/mp4_media_parser.cc

@@ -410,6 +410,7 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
 
     // Calculate duration (based on timescale).
     int64_t duration = 0;
+    bool mehd_header_carryover = false;
     if (track->media.header.duration > 0 &&
         track->media.header.duration != std::numeric_limits<uint64_t>::max()) {
       duration = track->media.header.duration;
@@ -419,6 +420,7 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
       DCHECK(moov_->header.timescale != 0);
       duration = Rescale(moov_->extends.header.fragment_duration,
                          moov_->header.timescale, timescale);
+      mehd_header_carryover = true;
     } else if (moov_->header.duration > 0 &&
                moov_->header.duration != std::numeric_limits<uint64_t>::max()) {
       DCHECK(moov_->header.timescale != 0);
@@ -593,6 +595,7 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
           num_channels, sampling_frequency, seek_preroll_ns, codec_delay_ns,
           max_bitrate, avg_bitrate, track->media.header.language.code,
           is_encrypted));
+      streams.back()->set_mehd_header_carryover(mehd_header_carryover);
 
       const EditList& edit_list = track->edit.list;
       if (edit_list.edits.size() == 1u) {
@@ -786,6 +789,7 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
           break;
         }
       }
+      video_stream_info->set_mehd_header_carryover(mehd_header_carryover);
 
       streams.push_back(video_stream_info);
     }

packager/media/formats/mp4/mp4_muxer.cc

@@ -248,7 +248,8 @@ Status MP4Muxer::DelayInitializeMuxer() {
       ftyp->compatible_brands.push_back(FOURCC_cmfc);
 
     // Carry over movie extends header duration from init segment.
-    if (streams()[0].get()->duration() > 0) {
+    if (streams()[0].get()->duration() > 0 &&
+        streams()[0].get()->is_mehd_header_duration()) {
       moov->extends.header.fragment_duration = streams()[0].get()->duration();
     }
   }