hlsdemux2: Add a timestamp to the playlist

Store the timestamp for this playlist. If valid it represents the monotonic time
at which the data was retrieved, minus any proxy cache Age field.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3883>

subprojects/gst-plugins-good/ext/adaptivedemux2/hls/gsthlsdemux.c

@@ -941,7 +941,7 @@ gst_hls_demux_process_manifest (GstAdaptiveDemux * demux, GstBuffer * buf)
 
   if (hlsdemux->master->is_simple) {
     simple_media_playlist =
-        gst_hls_media_playlist_parse (playlist,
+        gst_hls_media_playlist_parse (playlist, GST_CLOCK_TIME_NONE,
         gst_adaptive_demux_get_manifest_ref_uri (demux), NULL);
   }
 
@@ -2066,6 +2066,12 @@ download_media_playlist (GstHLSDemux * demux, gchar * uri, GError ** err,
           "Couldn't download the playlist");
     goto out;
   }
+
+  /* Calculate the newest time we know this playlist was valid to store on the HLS Media Playlist */
+  GstClockTime playlist_ts =
+      MAX (0, GST_CLOCK_DIFF (download_request_get_age (download),
+          download->download_start_time));
+
   buf = download_request_take_buffer (download);
   download_request_unref (download);
 
@@ -2090,7 +2096,9 @@ download_media_playlist (GstHLSDemux * demux, gchar * uri, GError ** err,
     playlist->reloaded = TRUE;
     g_free (playlist_data);
   } else {
-    playlist = gst_hls_media_playlist_parse (playlist_data, uri, base_uri);
+    playlist =
+        gst_hls_media_playlist_parse (playlist_data, playlist_ts, uri,
+        base_uri);
     if (!playlist) {
       GST_WARNING_OBJECT (demux, "Couldn't parse playlist");
       if (err)
@@ -2424,8 +2432,6 @@ gst_hls_demux_stream_update_media_playlist (GstHLSDemux * demux,
     GST_WARNING_OBJECT (stream, "Could not get playlist '%s'", *uri);
     return GST_FLOW_ERROR;
   }
-  stream->playlist_last_update_time =
-      gst_adaptive_demux2_get_monotonic_time (GST_ADAPTIVE_DEMUX (demux));
 
   /* Check if a redirect happened */
   if (g_strcmp0 (*uri, new_playlist->uri)) {
@@ -2660,7 +2666,7 @@ gst_hls_demux_stream_update_fragment_info (GstAdaptiveDemux2Stream * stream)
       stream->current_position : GST_CLOCK_TIME_NONE;
   GstClockTime playlist_age =
       gst_adaptive_demux2_get_monotonic_time (GST_ADAPTIVE_DEMUX (demux)) -
-      hlsdemux_stream->playlist_last_update_time;
+      hlsdemux_stream->playlist->playlist_ts;
   GST_DEBUG_OBJECT (stream,
       "Updating fragment information, current_position:%" GST_TIME_FORMAT
       " which is %" GST_STIME_FORMAT " from live edge. Playlist age %"

subprojects/gst-plugins-good/ext/adaptivedemux2/hls/m3u8.c

@@ -404,6 +404,7 @@ gst_hls_media_playlist_new (const gchar * uri, const gchar * base_uri)
 
   m3u8 = g_new0 (GstHLSMediaPlaylist, 1);
 
+  m3u8->playlist_ts = GST_CLOCK_TIME_NONE;
   m3u8->uri = g_strdup (uri);
   m3u8->base_uri = g_strdup (base_uri);
 
@@ -763,8 +764,8 @@ malformed_line:
 
 /* Parse and create a new GstHLSMediaPlaylist */
 GstHLSMediaPlaylist *
-gst_hls_media_playlist_parse (gchar * data, const gchar * uri,
-    const gchar * base_uri)
+gst_hls_media_playlist_parse (gchar * data,
+    GstClockTime playlist_ts, const gchar * uri, const gchar * base_uri)
 {
   gchar *input_data = data;
   GstHLSMediaPlaylist *self;
@@ -784,6 +785,7 @@ gst_hls_media_playlist_parse (gchar * data, const gchar * uri,
   GPtrArray *partial_segments = NULL;
   gboolean is_gap = FALSE;
 
+  GST_LOG ("playlist ts: %" GST_TIMEP_FORMAT, &playlist_ts);
   GST_LOG ("uri: %s", uri);
   GST_LOG ("base_uri: %s", base_uri);
   GST_TRACE ("data:\n%s", data);
@@ -801,6 +803,7 @@ gst_hls_media_playlist_parse (gchar * data, const gchar * uri,
   }
 
   self = gst_hls_media_playlist_new (uri, base_uri);
+  self->playlist_ts = playlist_ts;
 
   /* Store a copy of the data */
   self->last_data = g_strdup (data);

subprojects/gst-plugins-good/ext/adaptivedemux2/hls/m3u8.h

@@ -97,6 +97,8 @@ struct _GstHLSMediaPlaylist
   gchar *uri;                   /* actually downloaded URI */
   gchar *base_uri;              /* URI to use as base for resolving relative URIs.
                                  * This will be different to uri in case of redirects */
+  GstClockTime playlist_ts;     /* Monotonic clock time estimate for this playlist's validity from download time and cached Age */
+
   /* Base Tag */
   gint version;                 /* EXT-X-VERSION (default 1) */
 
@@ -272,6 +274,7 @@ gst_hls_media_playlist_has_same_data (GstHLSMediaPlaylist * m3u8,
 
 GstHLSMediaPlaylist *
 gst_hls_media_playlist_parse (gchar        * data,
+			      GstClockTime playlist_ts,
 			      const gchar  * uri,
 			      const gchar  * base_uri);
 

subprojects/gst-plugins-good/tests/check/elements/hlsdemux_m3u8.c

@@ -265,7 +265,7 @@ load_m3u8 (const gchar * data)
   GstHLSMediaPlaylist *playlist;
 
   playlist = gst_hls_media_playlist_parse (g_strdup (data),
-      "http://localhost/test.m3u8", NULL);
+      GST_CLOCK_TIME_NONE, "http://localhost/test.m3u8", NULL);
   fail_unless (playlist != NULL);
 
   return playlist;
@@ -556,7 +556,7 @@ GST_START_TEST (test_parse_invalid_playlist)
   GstHLSMediaPlaylist *pl;
 
   pl = gst_hls_media_playlist_parse (g_strdup ("#INVALID"),
-      "http://localhost/test.m3u8", NULL);
+      GST_CLOCK_TIME_NONE, "http://localhost/test.m3u8", NULL);
   fail_if (pl != NULL);
 }