Fix subtitles (seen in DVB) which have a specified `to' time but

then are terminated earlier than that by a num_rects=0 subtitle.

4 files changed, 37 insertions, 30 deletions

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index ddc563b98..b7dced34d 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -510,13 +510,11 @@ FFmpegDecoder::decode_subtitle_packet ()
 	ContentTimePeriod period;
 	period.from = sub_period.from + _pts_offset;
 	subtitle->set_position (period.from);
-	if (sub_period.to) {
-		/* We already know the subtitle period `to' time */
-		period.to = sub_period.to.get() + _pts_offset;
-	} else {
-		/* We have to look up the `to' time in the stream's records */
-		period.to = ffmpeg_content()->subtitle_stream()->find_subtitle_to (subtitle_id (sub));
-	}
+	/* We can't trust the `to' time from sub_period as there are some decoders which
+	   give a sub_period time for `to' which is subsequently overridden by a `stop' subtitle;
+	   see also FFmpegExaminer.
+	*/
+	period.to = ffmpeg_content()->subtitle_stream()->find_subtitle_to (subtitle_id (sub));
 
 	for (unsigned int i = 0; i < sub.num_rects; ++i) {
 		AVSubtitleRect const * rect = sub.rects[i];
diff --git a/src/lib/ffmpeg_examiner.cc b/src/lib/ffmpeg_examiner.cc
index 4c2040f52..271180d5d 100644
--- a/src/lib/ffmpeg_examiner.cc
+++ b/src/lib/ffmpeg_examiner.cc
@@ -236,32 +236,24 @@ FFmpegExaminer::subtitle_packet (AVCodecContext* context, shared_ptr<FFmpegSubti
 		FFmpegSubtitlePeriod const period = subtitle_period (sub);
 		bool const starts_image = subtitle_starts_image (sub);
 
+		/* Some streams (notably DVB streams) have subtitles which have a specified end time
+		   but which are then stopped earlier than this by a zero-num_rect subtitle.
+		*/
+
 		LastSubtitleMap::iterator last = _last_subtitle_start.find (stream);
-		if (last != _last_subtitle_start.end() && last->second) {
-			/* We have seen the start of a subtitle but not yet the end.  Whatever this is
-			   finishes the previous subtitle, so add it */
-			if (last->second->image) {
-				stream->add_image_subtitle (last->second->id, ContentTimePeriod (last->second->time, period.from));
-			} else {
-				stream->add_text_subtitle (last->second->id, ContentTimePeriod (last->second->time, period.from));
-			}
-			if (sub.num_rects == 0) {
-				/* This is a `proper' end-of-subtitle */
-				_last_subtitle_start[stream] = optional<SubtitleStart> ();
+		if (sub.num_rects == 0 && last != _last_subtitle_start.end() && last->second) {
+			/* Set (or fix) the `to' time for the last subtitle */
+			stream->set_subtitle_to (last->second->id, period.from);
+			_last_subtitle_start[stream] = optional<SubtitleStart> ();
+		} else if (sub.num_rects > 0) {
+			/* Add a subtitle; if we don't know the `to' time we set it to the from time and fix it later */
+			if (starts_image) {
+				stream->add_image_subtitle (id, ContentTimePeriod (period.from, period.to.get_value_or (period.from)));
 			} else {
-				/* This is just another subtitle, so we start again */
-				_last_subtitle_start[stream] = SubtitleStart (id, starts_image, period.from);
-			}
-		} else if (sub.num_rects >= 1) {
-			if (period.to) {
-				if (starts_image) {
-					stream->add_image_subtitle (id, ContentTimePeriod (period.from, period.to.get ()));
-				} else {
-					stream->add_text_subtitle (id, ContentTimePeriod (period.from, period.to.get ()));
-				}
-			} else {
-				_last_subtitle_start[stream] = SubtitleStart (id, starts_image, period.from);
+				stream->add_text_subtitle (id, ContentTimePeriod (period.from, period.to.get_value_or (period.from)));
 			}
+
+			_last_subtitle_start[stream] = SubtitleStart (id, starts_image, period.from);
 		}
 
 		for (unsigned int i = 0; i < sub.num_rects; ++i) {
diff --git a/src/lib/ffmpeg_subtitle_stream.cc b/src/lib/ffmpeg_subtitle_stream.cc
index 627b0fef1..57c54e1ea 100644
--- a/src/lib/ffmpeg_subtitle_stream.cc
+++ b/src/lib/ffmpeg_subtitle_stream.cc
@@ -219,3 +219,19 @@ FFmpegSubtitleStream::has_image () const
 {
 	return !_image_subtitles.empty ();
 }
+
+void
+FFmpegSubtitleStream::set_subtitle_to (string id, ContentTime to)
+{
+	PeriodMap::iterator i = _image_subtitles.find (id);
+	if (i != _image_subtitles.end ()) {
+		i->second.to = to;
+	} else {
+		i = _text_subtitles.find (id);
+		if (i != _text_subtitles.end ()) {
+			i->second.to = to;
+		} else {
+			DCPOMATIC_ASSERT (false);
+		}
+	}
+}
diff --git a/src/lib/ffmpeg_subtitle_stream.h b/src/lib/ffmpeg_subtitle_stream.h
index 6d4853b8d..33247558f 100644
--- a/src/lib/ffmpeg_subtitle_stream.h
+++ b/src/lib/ffmpeg_subtitle_stream.h
@@ -36,6 +36,7 @@ public:
 
 	void add_image_subtitle (std::string id, ContentTimePeriod period);
 	void add_text_subtitle (std::string id, ContentTimePeriod period);
+	void set_subtitle_to (std::string id, ContentTime to);
 	std::list<ContentTimePeriod> image_subtitles_during (ContentTimePeriod period, bool starting) const;
 	std::list<ContentTimePeriod> text_subtitles_during (ContentTimePeriod period, bool starting) const;
 	ContentTime find_subtitle_to (std::string id) const;