+/*
+ Copyright (C) 2018 Carl Hetherington <cth@carlh.net>
+
+ This file is part of DCP-o-matic.
+
+ DCP-o-matic is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ DCP-o-matic is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with DCP-o-matic. If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+#ifndef DCPOMATIC_DELAY_H
+#define DCPOMATIC_DELAY_H
+
+#include "types.h"
+#include "video_adjuster.h"
+#include "content_video.h"
+#include <boost/signals2.hpp>
+
+class Piece;
+
+/** A class which `delays' received video by 2 frames; i.e. when it receives
+ * a video frame it emits the last-but-one it received.
+ */
+class Delay : public VideoAdjuster
+{
+public:
+ void video (boost::weak_ptr<Piece>, ContentVideo video);
+
+private:
+ boost::optional<ContentVideo> _last;
+};
+
+#endif