hlsdemux2: Mark locations where partial segments need handling

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

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

@@ -974,6 +974,7 @@ out:
         GST_STIME_ARGS (current_segment->stream_time +
             current_segment->duration));
 
+    /* FIXME: Could seek to an INDEPENDENT partial segment in LL-HLS */
     candidate_segment =
         gst_hls_media_playlist_seek (hls_stream->playlist, TRUE,
         GST_SEEK_FLAG_SNAP_NEAREST, low_stream_time);

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

@@ -514,6 +514,7 @@ gst_hls_demux_stream_seek (GstAdaptiveDemux2Stream * stream, gboolean forward,
     }
   }
 
+  /* FIXME: Allow jumping to partial segments in LL-HLS? */
   new_position =
       gst_hls_media_playlist_seek (hls_stream->playlist, forward, flags, ts);
   if (new_position) {
@@ -1350,6 +1351,7 @@ gst_hlsdemux_handle_internal_time (GstHLSDemux * demux,
       GST_DEBUG_OBJECT (hls_stream,
           "Trying to seek to the correct segment for %" GST_STIME_FORMAT,
           GST_STIME_ARGS (current_stream_time));
+      /* FIXME: Allow jumping to partial segments in LL-HLS */
       actual_segment =
           gst_hls_media_playlist_seek (hls_stream->playlist, TRUE,
           GST_SEEK_FLAG_SNAP_NEAREST, current_stream_time);
@@ -1823,9 +1825,10 @@ gst_hls_demux_stream_advance_fragment (GstAdaptiveDemux2Stream * stream)
       GST_STIME_ARGS (hlsdemux_stream->current_segment->stream_time),
       GST_STR_NULL (hlsdemux_stream->current_segment->uri));
 
+  /* FIXME: In LL-HLS, handle advancing into the partial-only segment */
   new_segment =
       gst_hls_media_playlist_advance_fragment (hlsdemux_stream->playlist,
-      hlsdemux_stream->current_segment, stream->demux->segment.rate > 0);
+      hlsdemux_stream->current_segment, stream->demux->segment.rate > 0, FALSE);
   if (new_segment) {
     hlsdemux_stream->reset_pts = FALSE;
     if (new_segment->discont_sequence !=
@@ -2224,6 +2227,11 @@ gst_hls_demux_stream_update_media_playlist (GstHLSDemux * demux,
     new_segment =
         gst_hls_media_playlist_sync_to_segment (new_playlist,
         stream->current_segment);
+
+    /* FIXME: Handle LL-HLS partial segment sync */
+    if (new_segment && new_segment->partial_only)
+      new_segment = NULL;
+
     if (new_segment) {
       if (new_segment->discont_sequence !=
           stream->current_segment->discont_sequence)
@@ -2385,6 +2393,7 @@ gst_hls_demux_stream_update_fragment_info (GstAdaptiveDemux2Stream * stream)
       GST_DEBUG_OBJECT (stream,
           "Looking up segment for position %" GST_TIME_FORMAT,
           GST_TIME_ARGS (stream->current_position));
+      /* FIXME: Look up partial segments in LL-HLS */
       hlsdemux_stream->current_segment =
           gst_hls_media_playlist_seek (hlsdemux_stream->playlist, TRUE,
           GST_SEEK_FLAG_SNAP_NEAREST, stream->current_position);

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

@@ -1218,6 +1218,11 @@ gst_hls_media_playlist_seek (GstHLSMediaPlaylist * playlist, gboolean forward,
   for (idx = 0; idx < playlist->segments->len; idx++) {
     GstM3U8MediaSegment *cand = g_ptr_array_index (playlist->segments, idx);
 
+    /* If only full segments was request, skip any segment that
+     * only has EXT-X-PARTs attached */
+    if (cand->partial_only && !(flags & GST_HLS_M3U8_SEEK_FLAG_ALLOW_PARTIAL))
+      continue;
+
     if ((forward & snap_after) || snap_nearest) {
       if (cand->stream_time >= ts ||
           (snap_nearest && (ts - cand->stream_time < cand->duration / 2))) {
@@ -1736,7 +1741,8 @@ gst_hls_media_playlist_has_next_fragment (GstHLSMediaPlaylist * m3u8,
 
 GstM3U8MediaSegment *
 gst_hls_media_playlist_advance_fragment (GstHLSMediaPlaylist * m3u8,
-    GstM3U8MediaSegment * current, gboolean forward)
+    GstM3U8MediaSegment * current, gboolean forward,
+    gboolean allow_partial_only_segment)
 {
   GstM3U8MediaSegment *file = NULL;
   guint idx;
@@ -1768,6 +1774,12 @@ gst_hls_media_playlist_advance_fragment (GstHLSMediaPlaylist * m3u8,
             idx - 1));
   }
 
+  if (file && file->partial_only && !allow_partial_only_segment) {
+    GST_LOG
+        ("Ignoring segment with only partials as full segment was requested");
+    file = NULL;
+  }
+
   if (file)
     GST_DEBUG ("Advanced to segment sn:%" G_GINT64_FORMAT " dsn:%"
         G_GINT64_FORMAT, file->sequence, file->discont_sequence);

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

@@ -65,6 +65,11 @@ typedef enum {
   GST_HLS_PLAYLIST_TYPE_VOD,
 } GstHLSPlaylistType;
 
+/* Extra seek flag extensions for partial segment handling
+ * Values are chosen to avoid collision with the core GST_SEEK_FLAG_*
+ * flags */
+#define GST_HLS_M3U8_SEEK_FLAG_ALLOW_PARTIAL (1 << 16)  /* Allow seeking to a partial segment */
+
 /**
  * GstHLSMediaPlaylist:
  *
@@ -271,7 +276,8 @@ gst_hls_media_playlist_has_next_fragment    (GstHLSMediaPlaylist * m3u8,
 GstM3U8MediaSegment *
 gst_hls_media_playlist_advance_fragment     (GstHLSMediaPlaylist * m3u8,
 					     GstM3U8MediaSegment * current,
-					     gboolean  forward);
+					     gboolean  forward,
+					     gboolean allow_partial_only_segment);
 
 GstM3U8MediaSegment *
 gst_hls_media_playlist_get_starting_segment (GstHLSMediaPlaylist *self);

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

@@ -690,7 +690,7 @@ GST_START_TEST (test_advance_fragment)
   gst_m3u8_media_segment_unref (mf);
 
   /* Check next media segments */
-  mf = gst_hls_media_playlist_advance_fragment (pl, mf, TRUE);
+  mf = gst_hls_media_playlist_advance_fragment (pl, mf, TRUE, FALSE);
   fail_unless (mf != NULL);
   assert_equals_int (mf->discont, FALSE);
   assert_equals_string (mf->uri, "http://media.example.com/all.ts");
@@ -701,7 +701,7 @@ GST_START_TEST (test_advance_fragment)
   gst_m3u8_media_segment_unref (mf);
 
   /* Check next media segments */
-  mf = gst_hls_media_playlist_advance_fragment (pl, mf, TRUE);
+  mf = gst_hls_media_playlist_advance_fragment (pl, mf, TRUE, FALSE);
   assert_equals_int (mf->discont, FALSE);
   assert_equals_string (mf->uri, "http://media.example.com/all.ts");
   assert_equals_uint64 (mf->stream_time, 20 * GST_SECOND);