dvbsuboverlay: ensure valid subtitle running time by proper clipping

In particular, pass buffer timestamp (pts) to dvb_sub, and then clip
and convert to running time when the duration (timeout) is known after
decoding it.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=660233

1 files changed, 31 insertions, 13 deletions

diff --git a/gst/dvbsuboverlay/gstdvbsuboverlay.c b/gst/dvbsuboverlay/gstdvbsuboverlay.c
index 80f0ea25a..e22a6a1d7 100644
--- a/gst/dvbsuboverlay/gstdvbsuboverlay.c
+++ b/gst/dvbsuboverlay/gstdvbsuboverlay.c
@@ -728,9 +728,8 @@ gst_dvbsub_overlay_process_text (GstDVBSubOverlay * overlay, GstBuffer * buffer,
   guint size = GST_BUFFER_SIZE (buffer);
 
   GST_DEBUG_OBJECT (overlay,
-      "Processing subtitles with fake PTS=%" G_GUINT64_FORMAT
-      " which is a running time of %" GST_TIME_FORMAT,
-      pts, GST_TIME_ARGS (pts));
+      "Processing subtitles with PTS=%" G_GUINT64_FORMAT
+      " which is a time of %" GST_TIME_FORMAT, pts, GST_TIME_ARGS (pts));
   GST_DEBUG_OBJECT (overlay, "Feeding %u bytes to libdvbsub", size);
   g_mutex_lock (overlay->dvbsub_mutex);
   dvb_sub_feed_with_pts (overlay->dvb_sub, pts, data, size);
@@ -750,6 +749,7 @@ new_dvb_subtitles_cb (DvbSub * dvb_sub, DVBSubtitles * subs, gpointer user_data)
 {
   GstDVBSubOverlay *overlay = GST_DVBSUB_OVERLAY (user_data);
   int max_page_timeout;
+  gint64 start, stop;
 
   max_page_timeout = g_atomic_int_get (&overlay->max_page_timeout);
   if (max_page_timeout > 0)
@@ -757,12 +757,38 @@ new_dvb_subtitles_cb (DvbSub * dvb_sub, DVBSubtitles * subs, gpointer user_data)
 
   GST_INFO_OBJECT (overlay,
       "New DVB subtitles arrived with a page_time_out of %d and %d regions for PTS=%"
-      G_GUINT64_FORMAT ", which should be at running time %" GST_TIME_FORMAT,
+      G_GUINT64_FORMAT ", which should be at time %" GST_TIME_FORMAT,
       subs->page_time_out, subs->num_rects, subs->pts,
       GST_TIME_ARGS (subs->pts));
 
+  /* clip and convert to running time */
+  start = subs->pts;
+  stop = subs->pts + subs->page_time_out;
+
+  if (!(gst_segment_clip (&overlay->subtitle_segment, GST_FORMAT_TIME,
+              start, stop, &start, &stop)))
+    goto out_of_segment;
+
+  subs->page_time_out = stop - start;
+
+  gst_segment_to_running_time (&overlay->subtitle_segment, GST_FORMAT_TIME,
+      start);
+  g_assert (GST_CLOCK_TIME_IS_VALID (start));
+  subs->pts = start;
+
+  GST_DEBUG_OBJECT (overlay, "SUBTITLE real running time: %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (start));
+
   g_queue_push_tail (overlay->pending_subtitles, subs);
   overlay->pending_sub = FALSE;
+
+  return;
+
+out_of_segment:
+  {
+    GST_DEBUG_OBJECT (overlay, "subtitle out of segment, discarding");
+    dvb_subtitles_free (subs);
+  }
 }
 
 static GstFlowReturn
@@ -791,7 +817,6 @@ static GstFlowReturn
 gst_dvbsub_overlay_chain_text (GstPad * pad, GstBuffer * buffer)
 {
   GstDVBSubOverlay *overlay = GST_DVBSUB_OVERLAY (GST_PAD_PARENT (pad));
-  GstClockTime sub_running_time;
 
   GST_INFO_OBJECT (overlay, "subpicture/x-dvb buffer with size %u",
       GST_BUFFER_SIZE (buffer));
@@ -831,16 +856,9 @@ gst_dvbsub_overlay_chain_text (GstPad * pad, GstBuffer * buffer)
   gst_segment_set_last_stop (&overlay->subtitle_segment, GST_FORMAT_TIME,
       GST_BUFFER_TIMESTAMP (buffer));
 
-  sub_running_time =
-      gst_segment_to_running_time (&overlay->subtitle_segment, GST_FORMAT_TIME,
+  gst_dvbsub_overlay_process_text (overlay, buffer,
       GST_BUFFER_TIMESTAMP (buffer));
 
-  GST_DEBUG_OBJECT (overlay, "SUBTITLE real running time: %" GST_TIME_FORMAT,
-      GST_TIME_ARGS (sub_running_time));
-
-  /* FIXME: We are abusing libdvbsub pts value for tracking our gstreamer running time instead of real PTS. Should be mostly fine though... */
-  gst_dvbsub_overlay_process_text (overlay, buffer, sub_running_time);
-
   return GST_FLOW_OK;
 }