Specify Initial Sequence Number

[sammirata]

Here is a sample command line:
packager-linux input=s00015072.ts.25274682549.ts,stream_selector=video,init_segment=video.mp4,segment_template=video2-$Number$.mp4

[sammirata]

I answered my own question by looking at the code. There is no way to change the default of 1 as starting sequence number. Here is a patch that applies to latest version. It adds a new option to control the initial sequence number of the segmenter:

diff --git a/packager/app/muxer_flags.cc b/packager/app/muxer_flags.cc
index a18a4e7..888d486 100644
--- a/packager/app/muxer_flags.cc
+++ b/packager/app/muxer_flags.cc
@@ -50,3 +50,7 @@ DEFINE_bool(mp4_use_decoding_timestamp_in_timeline,
             "be used when generating media timeline, e.g. timestamps in sidx "
             "and mpd. This is to workaround a Chromium bug that decoding "
             "timestamp is used in buffered range, https://crbug.com/398130.");
+DEFINE_int32(mp4_sequence_number_initial,
+             1,
+             "This number allows for the customization of the "
+             "initial sequence_number in the mp4 moof->mfhd.");
\ No newline at end of file
diff --git a/packager/app/muxer_flags.h b/packager/app/muxer_flags.h
index a88a777..a096be4 100644
--- a/packager/app/muxer_flags.h
+++ b/packager/app/muxer_flags.h
@@ -20,5 +20,6 @@ DECLARE_int32(num_subsegments_per_sidx);
 DECLARE_string(temp_dir);
 DECLARE_bool(mp4_include_pssh_in_stream);
 DECLARE_bool(mp4_use_decoding_timestamp_in_timeline);
+DECLARE_int32(mp4_sequence_number_initial);
 
 #endif  // APP_MUXER_FLAGS_H_
diff --git a/packager/app/packager_main.cc b/packager/app/packager_main.cc
index fa7e034..e9d41be 100644
--- a/packager/app/packager_main.cc
+++ b/packager/app/packager_main.cc
@@ -284,6 +284,7 @@ base::Optional<PackagingParams> GetPackagingParams() {
   mp4_params.use_decoding_timestamp_in_timeline =
       FLAGS_mp4_use_decoding_timestamp_in_timeline;
   mp4_params.include_pssh_in_stream = FLAGS_mp4_include_pssh_in_stream;
+  mp4_params.sequence_number_initial = FLAGS_mp4_sequence_number_initial;
 
   packaging_params.output_media_info = FLAGS_output_media_info;
 
diff --git a/packager/media/formats/mp4/segmenter.cc b/packager/media/formats/mp4/segmenter.cc
index 8e1bb56..dfbf84c 100644
--- a/packager/media/formats/mp4/segmenter.cc
+++ b/packager/media/formats/mp4/segmenter.cc
@@ -84,7 +84,7 @@ Status Segmenter::Initialize(
 
   // Use the reference stream's time scale as movie time scale.
   moov_->header.timescale = sidx_->timescale;
-  moof_->header.sequence_number = 1;
+  moof_->header.sequence_number = options_.mp4_params.sequence_number_initial;
 
   // Fill in version information.
   const std::string version = GetPackagerVersion();
diff --git a/packager/media/public/mp4_output_params.h b/packager/media/public/mp4_output_params.h
index f9b83f1..4c39dd8 100644
--- a/packager/media/public/mp4_output_params.h
+++ b/packager/media/public/mp4_output_params.h
@@ -29,6 +29,7 @@ struct Mp4OutputParams {
   /// which is needed to workaround a Chromium bug that decoding timestamp is
   /// used in buffered range, https://crbug.com/398130.
   bool use_decoding_timestamp_in_timeline = false;
+  int sequence_number_initial = 1;
 };
 
 }  // namespace shaka

[vaage]

@sammirata Sorry for the lack of communication. If you would like to contribute to the shaka packager, please follow the instructions in CONTRIBUTING and then provide a pull request.

@kqyang Would this be a change we would be willing to accept?

[kqyang]

Yes! I'd hope to have native support for HLS to DASH conversion, but since it is not going to happen soon, @sammirata's method is an effective way to make it work right now.

@sammirata Sorry for not getting back to you earlier. As suggested by @vaage, we welcome pull requests. A quick question, are there any clients / players requires the sequence_number to be set properly? I know Chrome does not care about the value.

[vaage]

To make this issue appear nicer in the list of issues, I am going to rename it and move the description down here.

Is there a way to specify the sequence number when manually creating a single segment with a template? I could not find anything in the command line. I am working on a c# application that pulls HLS and converts it to HLS/fmp4 and Dash using the packager command line one segment at a time and the only thing I am missing is the sequence number assignment inside the mp4 files.

[sammirata]

I have submitted a pull request with the patch. This method has been used effectively to generate a valid HLS/fmp4 stream using an HLS/ts as source.

[vaage]

I have added the "Help Wanted" label since you submitted a pull request. The pull request is #350.