Stop erroneous addition of text subtitles to the lists (when

an image subtitle is completed with a rect count of zero) which
subsequently cause hangs while the decoder looks for these
phantom text subtitles.  Fixes #812.

3 files changed, 9 insertions, 8 deletions

diff --git a/src/lib/ffmpeg.cc b/src/lib/ffmpeg.cc
index 29dda1b9e..9d6921dcf 100644
--- a/src/lib/ffmpeg.cc
+++ b/src/lib/ffmpeg.cc
@@ -288,8 +288,9 @@ FFmpeg::subtitle_id (AVSubtitle const & sub)
 	return digester.get ();
 }
 
+/** @return true if sub starts a new image subtitle */
 bool
-FFmpeg::subtitle_is_image (AVSubtitle const & sub)
+FFmpeg::subtitle_starts_image (AVSubtitle const & sub)
 {
 	bool image = false;
 	bool text = false;
diff --git a/src/lib/ffmpeg.h b/src/lib/ffmpeg.h
index 9795b2229..43efcf74f 100644
--- a/src/lib/ffmpeg.h
+++ b/src/lib/ffmpeg.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2013-2016 Carl Hetherington <cth@carlh.net>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -58,7 +58,7 @@ protected:
 
 	static FFmpegSubtitlePeriod subtitle_period (AVSubtitle const & sub);
 	static std::string subtitle_id (AVSubtitle const & sub);
-	static bool subtitle_is_image (AVSubtitle const & sub);
+	static bool subtitle_starts_image (AVSubtitle const & sub);
 
 	boost::shared_ptr<const FFmpegContent> _ffmpeg_content;
 
diff --git a/src/lib/ffmpeg_examiner.cc b/src/lib/ffmpeg_examiner.cc
index 850b8ba5f..abca5fee7 100644
--- a/src/lib/ffmpeg_examiner.cc
+++ b/src/lib/ffmpeg_examiner.cc
@@ -217,13 +217,13 @@ FFmpegExaminer::subtitle_packet (AVCodecContext* context, shared_ptr<FFmpegSubti
 	if (avcodec_decode_subtitle2 (context, &sub, &frame_finished, &_packet) >= 0 && frame_finished) {
 		string id = subtitle_id (sub);
 		FFmpegSubtitlePeriod const period = subtitle_period (sub);
-		bool const image = subtitle_is_image (sub);
+		bool const starts_image = subtitle_starts_image (sub);
 
 		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 (image) {
+			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));
@@ -233,17 +233,17 @@ FFmpegExaminer::subtitle_packet (AVCodecContext* context, shared_ptr<FFmpegSubti
 				_last_subtitle_start[stream] = optional<SubtitleStart> ();
 			} else {
 				/* This is just another subtitle, so we start again */
-				_last_subtitle_start[stream] = SubtitleStart (id, image, period.from);
+				_last_subtitle_start[stream] = SubtitleStart (id, starts_image, period.from);
 			}
 		} else if (sub.num_rects == 1) {
 			if (period.to) {
-				if (image) {
+				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, image, period.from);
+				_last_subtitle_start[stream] = SubtitleStart (id, starts_image, period.from);
 			}
 		}