Merge remote-tracking branch 'github/master' into HEAD

AUTHORS

@@ -15,6 +15,7 @@
 
 Anders Hasselqvist <anders.hasselqvist@gmail.com>
 Chun-da Chen <capitalm.c@gmail.com>
+Daniel Cantarín <canta@canta.com.ar>
 Google Inc. <*@google.com>
 Leandro Moreira <leandro.ribeiro.moreira@gmail.com>
 Leo Law <leoltlaw.gh@gmail.com>

CONTRIBUTORS

@@ -25,6 +25,7 @@
 Anders Hasselqvist <anders.hasselqvist@gmail.com>
 Bei Li <beil@google.com>
 Chun-da Chen <capitalm.c@gmail.com>
+Daniel Cantarín <canta@canta.com.ar>
 David Cavar <pal3thorn@gmail.com>
 Gabe Kopley <gabe@philo.com>
 Haoming Chen <hmchen@google.com>

docs/source/options/hls_options.rst

@@ -51,3 +51,27 @@ HLS options
 
     Same as above, but this applies to text tracks only, and overrides the
     default language for text tracks.
+
+--hls_media_sequence_number <unsigned_number>
+
+    HLS uses the EXT-X-MEDIA-SEQUENCE tag at the start of a live playlist in
+    order to specify the first segment sequence number. This is because any
+    live playlist have a limited number of segments, and they also keep
+    updating with new segments while removing old ones. When a player refreshes
+    the playlist, this information is important for keeping track of segments
+    positions.
+
+    When the packager starts, it naturally starts this count from zero. However,
+    there are many situations where the packager may be restarted, without this
+    meaning starting this value from zero (but continuing a previous sequence).
+    The most common situations are problems in the encoder feeding the packager.
+
+    With those cases in mind, this parameter allows to set the initial
+    EXT-X-MEDIA-SEQUENCE value. This way, it's possible to continue the sequence
+    number from previous packager run.
+
+    For more information about the reasoning of this, please see issue
+    `#691 <https://github.com/google/shaka-packager/issues/691>`_.
+
+    The EXT-X-MEDIA-SEQUENCE documentation can be read here:
+    https://tools.ietf.org/html/rfc8216#section-4.3.3.2.

packager/app/hls_flags.cc

@@ -24,3 +24,9 @@ DEFINE_string(hls_playlist_type,
               "VOD, EVENT, or LIVE. This defines the EXT-X-PLAYLIST-TYPE in "
               "the HLS specification. For hls_playlist_type of LIVE, "
               "EXT-X-PLAYLIST-TYPE tag is omitted.");
+DEFINE_int32(hls_media_sequence_number,
+              0,
+              "Number. This HLS-only parameter defines the initial "
+              "EXT-X-MEDIA-SEQUENCE value, which allows continuous media "
+              "sequence across packager restarts. See #691 for more "
+              "information about the reasoning of this and its use cases.");

packager/app/hls_flags.h

@@ -13,5 +13,6 @@ DECLARE_string(hls_master_playlist_output);
 DECLARE_string(hls_base_url);
 DECLARE_string(hls_key_uri);
 DECLARE_string(hls_playlist_type);
+DECLARE_int32(hls_media_sequence_number);
 
 #endif  // PACKAGER_APP_HLS_FLAGS_H_

packager/app/packager_main.cc

@@ -470,6 +470,7 @@ base::Optional<PackagingParams> GetPackagingParams() {
       FLAGS_preserved_segments_outside_live_window;
   hls_params.default_language = FLAGS_default_language;
   hls_params.default_text_language = FLAGS_default_text_language;
+  hls_params.media_sequence_number = FLAGS_hls_media_sequence_number;
 
   TestParams& test_params = packaging_params.test_params;
   test_params.dump_stream_info = FLAGS_dump_stream_info;

packager/hls/base/media_playlist.cc

@@ -106,7 +106,7 @@ std::string CreatePlaylistHeader(
     uint32_t target_duration,
     HlsPlaylistType type,
     MediaPlaylist::MediaPlaylistStreamType stream_type,
-    int media_sequence_number,
+    uint32_t media_sequence_number,
     int discontinuity_sequence_number) {
   const std::string version = GetPackagerVersion();
   std::string version_line;
@@ -343,7 +343,12 @@ MediaPlaylist::MediaPlaylist(const HlsParams& hls_params,
     : hls_params_(hls_params),
       file_name_(file_name),
       name_(name),
-      group_id_(group_id) {}
+      group_id_(group_id),
+      media_sequence_number_(hls_params_.media_sequence_number) {
+        // When there's a forced media_sequence_number, start with discontinuity
+        if (media_sequence_number_ > 0)
+          entries_.emplace_back(new DiscontinuityEntry());
+      }
 
 MediaPlaylist::~MediaPlaylist() {}
 
@@ -390,6 +395,7 @@ bool MediaPlaylist::SetMediaInfo(const MediaInfo& media_info) {
   characteristics_ =
       std::vector<std::string>(media_info_.hls_characteristics().begin(),
                                media_info_.hls_characteristics().end());
+
   return true;
 }
 

packager/hls/base/media_playlist.h

@@ -236,7 +236,7 @@ class MediaPlaylist {
   std::string codec_;
   std::string language_;
   std::vector<std::string> characteristics_;
-  int media_sequence_number_ = 0;
+  uint32_t media_sequence_number_ = 0;
   bool inserted_discontinuity_tag_ = false;
   int discontinuity_sequence_number_ = 0;
 

packager/hls/public/hls_params.h

@@ -56,6 +56,9 @@ struct HlsParams {
   /// be populated from segment duration specified in ChunkingParams if not
   /// specified.
   double target_segment_duration = 0;
+  /// Custom EXT-X-MEDIA-SEQUENCE value to allow continuous media playback
+  /// across packager restarts. See #691 for details.
+  uint32_t media_sequence_number = 0;
 };
 
 }  // namespace shaka

packager/media/formats/mp2t/ts_segmenter.cc

@@ -125,7 +125,7 @@ void TsSegmenter::SetTsWriterFileOpenedForTesting(bool value) {
   ts_writer_file_opened_ = value;
 }
 
-Status TsSegmenter::OpenNewSegmentIfClosed(uint32_t next_pts) {
+Status TsSegmenter::OpenNewSegmentIfClosed(int64_t next_pts) {
   if (ts_writer_file_opened_)
     return Status::OK;
   const std::string segment_name =

packager/media/formats/mp2t/ts_segmenter.h

@@ -71,7 +71,7 @@ class TsSegmenter {
   void SetTsWriterFileOpenedForTesting(bool value);
 
  private:
-  Status OpenNewSegmentIfClosed(uint32_t next_pts);
+  Status OpenNewSegmentIfClosed(int64_t next_pts);
 
   // Writes PES packets (carried in TsPackets) to a file. If a file is not open,
   // it will open one. This will not close the file.