Fix subtitle display when the next subtitle is decoded before the

previous one has finished; this requires that more than one subtitle be
kept by the player.

Reported-by: Matthias Damm

4 files changed, 61 insertions, 13 deletions

diff --git a/src/lib/player.cc b/src/lib/player.cc
index d0653bc43..1bb2e7cf4 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -219,17 +219,34 @@ Player::process_video (weak_ptr<Piece> weak_piece, shared_ptr<const Image> image
 			)
 		);
 	
-	if (_film->with_subtitles () && _subtitle && _subtitle->out_image() && _subtitle->covers (time)) {
+	if (_film->with_subtitles ()) {
+		for (list<Subtitle>::const_iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
+			if (i->covers (time)) {
+				/* This may be true for more than one of _subtitles, but the last (latest-starting)
+				   one is the one we want to use, so that's ok.
+				*/
+				Position<int> const container_offset (
+					(_video_container_size.width - image_size.width) / 2,
+					(_video_container_size.height - image_size.width) / 2
+					);
+				
+				pi->set_subtitle (i->out_image(), i->out_position() + container_offset);
+			}
+		}
+	}
 
-		Position<int> const container_offset (
-			(_video_container_size.width - image_size.width) / 2,
-			(_video_container_size.height - image_size.width) / 2
-			);
+	/* Clear out old subtitles */
+	for (list<Subtitle>::iterator i = _subtitles.begin(); i != _subtitles.end(); ) {
+		list<Subtitle>::iterator j = i;
+		++j;
+		
+		if (i->ends_before (time)) {
+			_subtitles.erase (i);
+		}
 
-		pi->set_subtitle (_subtitle->out_image(), _subtitle->out_position() + container_offset);
+		i = j;
 	}
-		
-					    
+
 #ifdef DCPOMATIC_DEBUG
 	_last_video = piece->content;
 #endif
@@ -466,9 +483,10 @@ Player::content_changed (weak_ptr<Content> w, int property, bool frequent)
 		property == SubtitleContentProperty::SUBTITLE_SCALE
 		) {
 
-		if (_subtitle) {
-			_subtitle->update (_film, _video_container_size);
+		for (list<Subtitle>::iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
+			i->update (_film, _video_container_size);
 		}
+		
 		Changed (frequent);
 
 	} else if (
@@ -576,7 +594,14 @@ Player::film_changed (Film::Property p)
 void
 Player::process_subtitle (weak_ptr<Piece> weak_piece, shared_ptr<Image> image, dcpomatic::Rect<double> rect, Time from, Time to)
 {
-	_subtitle = Subtitle (_film, _video_container_size, weak_piece, image, rect, from, to);
+	if (!image) {
+		/* A null image means that we should stop any current subtitles at `from' */
+		for (list<Subtitle>::iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
+			i->set_stop (from);
+		}
+	} else {
+		_subtitles.push_back (Subtitle (_film, _video_container_size, weak_piece, image, rect, from, to));
+	}
 }
 
 /** Re-emit the last frame that was emitted, using current settings for crop, ratio, scaler and subtitles.
diff --git a/src/lib/player.h b/src/lib/player.h
index 5dad80ec7..4d911a83b 100644
--- a/src/lib/player.h
+++ b/src/lib/player.h
@@ -143,7 +143,7 @@ private:
 	boost::shared_ptr<PlayerImage> _black_frame;
 	std::map<boost::shared_ptr<AudioContent>, boost::shared_ptr<Resampler> > _resamplers;
 
-	boost::optional<Subtitle> _subtitle;
+	std::list<Subtitle> _subtitles;
 
 #ifdef DCPOMATIC_DEBUG
 	boost::shared_ptr<Content> _last_video;
diff --git a/src/lib/subtitle.cc b/src/lib/subtitle.cc
index f348833b0..0d18861c4 100644
--- a/src/lib/subtitle.cc
+++ b/src/lib/subtitle.cc
@@ -97,6 +97,8 @@ Subtitle::update (shared_ptr<const Film> film, libdcp::Size video_container_size
 	
 	_out_from = from + piece->content->position ();
 	_out_to = to + piece->content->position ();
+
+	check_out_to ();
 }
 
 bool
@@ -104,3 +106,11 @@ Subtitle::covers (Time t) const
 {
 	return _out_from <= t && t <= _out_to;
 }
+
+void
+Subtitle::check_out_to ()
+{
+	if (_stop && _out_to > _stop.get ()) {
+		_out_to = _stop.get ();
+	}
+}
diff --git a/src/lib/subtitle.h b/src/lib/subtitle.h
index 7ba5912e0..c74f5c1b9 100644
--- a/src/lib/subtitle.h
+++ b/src/lib/subtitle.h
@@ -19,6 +19,7 @@
 
 #include <boost/shared_ptr.hpp>
 #include <boost/weak_ptr.hpp>
+#include <boost/optional.hpp>
 #include <libdcp/util.h>
 #include "rect.h"
 #include "types.h"
@@ -34,8 +35,15 @@ public:
 	Subtitle (boost::shared_ptr<const Film>, libdcp::Size, boost::weak_ptr<Piece>, boost::shared_ptr<Image>, dcpomatic::Rect<double>, Time, Time);
 
 	void update (boost::shared_ptr<const Film>, libdcp::Size);
+	void set_stop (Time t) {
+		_stop = t;
+		check_out_to ();
+	}
 
 	bool covers (Time t) const;
+	bool ends_before (Time t) const {
+		return _out_to < t;
+	}
 
 	boost::shared_ptr<Image> out_image () const {
 		return _out_image;
@@ -45,7 +53,9 @@ public:
 		return _out_position;
 	}
 	
-private:	
+private:
+	void check_out_to ();
+	
 	boost::weak_ptr<Piece> _piece;
 	boost::shared_ptr<Image> _in_image;
 	dcpomatic::Rect<double> _in_rect;
@@ -56,4 +66,7 @@ private:
 	Position<int> _out_position;
 	Time _out_from;
 	Time _out_to;
+
+	/** Time at which this subtitle should stop (overriding _out_to) */
+	boost::optional<Time> _stop;
 };