Nicer fix for 2D-labelled-3D checking from master.

9 files changed, 155 insertions, 31 deletions

diff --git a/src/lib/dcp_decoder.cc b/src/lib/dcp_decoder.cc
index 03ac66e94..19831185d 100644
--- a/src/lib/dcp_decoder.cc
+++ b/src/lib/dcp_decoder.cc
@@ -29,6 +29,7 @@
 #include "image.h"
 #include "config.h"
 #include "digester.h"
+#include "frame_interval_checker.h"
 #include <dcp/dcp.h>
 #include <dcp/cpl.h>
 #include <dcp/reel.h>
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 2f92b9b7c..77b608fa8 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -42,6 +42,7 @@
 #include "compose.hpp"
 #include "text_content.h"
 #include "audio_content.h"
+#include "frame_interval_checker.h"
 #include <dcp/subtitle_string.h>
 #include <sub/ssa_reader.h>
 #include <sub/subtitle.h>
diff --git a/src/lib/frame_interval_checker.cc b/src/lib/frame_interval_checker.cc
new file mode 100644
index 000000000..27c0224ec
--- /dev/null
+++ b/src/lib/frame_interval_checker.cc
@@ -0,0 +1,66 @@
+/*
+    Copyright (C) 2020 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/>.
+
+*/
+
+#include "frame_interval_checker.h"
+
+using namespace dcpomatic;
+
+int const FrameIntervalChecker::_frames = 16;
+
+void
+FrameIntervalChecker::feed (ContentTime time, double frame_rate)
+{
+	/* The caller isn't meant to feed too much data before
+	   calling guess() and destroying the FrameIntervalChecker.
+	 */
+	DCPOMATIC_ASSERT (_intervals.size() < _frames);
+
+	if (_last) {
+		_intervals.push_back ((time - *_last).seconds() * frame_rate);
+	}
+
+	_last = time;
+}
+
+FrameIntervalChecker::Guess
+FrameIntervalChecker::guess () const
+{
+	if (_intervals.size() < _frames) {
+		/* How soon can you land?
+		 * I can't tell.
+		 * You can tell me, I'm a doctor.
+		 * Nom I mean I'm just not sure.
+		 * Can't you take a guess?
+		 * Well, not for another two hours.
+		 * You can't take a guess for another two hours?
+		 */
+		return AGAIN;
+	}
+
+	int near_1 = 0;
+	BOOST_FOREACH (double i, _intervals) {
+		if (i > 0.5) {
+			++near_1;
+		}
+	}
+
+	return (near_1 < 3 * _frames / 4) ? PROBABLY_3D : PROBABLY_NOT_3D;
+}
+
diff --git a/src/lib/frame_interval_checker.h b/src/lib/frame_interval_checker.h
new file mode 100644
index 000000000..a8db31a49
--- /dev/null
+++ b/src/lib/frame_interval_checker.h
@@ -0,0 +1,50 @@
+/*
+    Copyright (C) 2020 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/>.
+
+*/
+
+#include "dcpomatic_time.h"
+#include <boost/optional.hpp>
+#include <boost/noncopyable.hpp>
+#include <vector>
+
+class FrameIntervalChecker : public boost::noncopyable
+{
+public:
+	void feed (dcpomatic::ContentTime time, double frame_rate);
+
+	enum Guess
+	{
+		AGAIN,
+		PROBABLY_3D,
+		PROBABLY_NOT_3D
+	};
+
+	Guess guess () const;
+
+private:
+	boost::optional<dcpomatic::ContentTime> _last;
+	/** Intervals of last frames, in fractions of a frame; i.e. 1 in here
+	 *  means the last two frames were one frame interval apart according
+	 *  to the frame rate passed to ::feed().
+	 */
+	std::vector<double> _intervals;
+
+	static int const _frames;
+};
+
diff --git a/src/lib/image_decoder.cc b/src/lib/image_decoder.cc
index 8aa3f6a99..15187b11b 100644
--- a/src/lib/image_decoder.cc
+++ b/src/lib/image_decoder.cc
@@ -27,6 +27,7 @@
 #include "film.h"
 #include "exceptions.h"
 #include "video_content.h"
+#include "frame_interval_checker.h"
 #include <boost/filesystem.hpp>
 #include <iostream>
 
diff --git a/src/lib/video_decoder.cc b/src/lib/video_decoder.cc
index 508ed90b7..2850b5aa0 100644
--- a/src/lib/video_decoder.cc
+++ b/src/lib/video_decoder.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2018 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2020 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -23,6 +23,7 @@
 #include "raw_image_proxy.h"
 #include "film.h"
 #include "log.h"
+#include "frame_interval_checker.h"
 #include "compose.hpp"
 #include <boost/foreach.hpp>
 #include <iostream>
@@ -40,6 +41,7 @@ using namespace dcpomatic;
 VideoDecoder::VideoDecoder (Decoder* parent, shared_ptr<const Content> c)
 	: DecoderPart (parent)
 	, _content (c)
+	, _frame_interval_checker (new FrameIntervalChecker())
 {
 
 }
@@ -60,33 +62,33 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 		return;
 	}
 
-	/* Before we `re-write' the frame indexes of these incoming data we need to check for
-	   the case where the user has some 2D content which they have marked as 3D.  With 3D
-	   we should get two frames for each frame index, but in this `bad' case we only get
-	   one.  We need to throw an exception if this happens.
-	*/
-
-	if (_content->video->frame_type() == VIDEO_FRAME_TYPE_3D) {
-		if (_last_threed_frames.size() > 4) {
-			_last_threed_frames.erase (_last_threed_frames.begin());
-		}
-		_last_threed_frames.push_back (decoder_frame);
-		if (_last_threed_frames.size() == 4) {
-			if (_last_threed_frames[0] != _last_threed_frames[1] || _last_threed_frames[2] != _last_threed_frames[3]) {
-				boost::throw_exception (
-					DecodeError(
-						String::compose(
-							_("The content file %1 is set as 3D but does not appear to contain 3D images.  Please set it to 2D.  "
-							  "You can still make a 3D DCP from this content by ticking the 3D option in the DCP video tab."),
-							_content->path(0)
-							)
+	double const afr = _content->active_video_frame_rate(film);
+	VideoFrameType const vft = _content->video->frame_type();
+
+	ContentTime frame_time = ContentTime::from_frames (decoder_frame, afr);
+
+	/* Do some heuristics to try and spot the case where the user sets content to 3D
+	 * when it is not.  We try to tell this by looking at the differences in time between
+	 * the first few frames.  Real 3D content should have two frames for each timestamp.
+	 */
+	if (_frame_interval_checker) {
+		_frame_interval_checker->feed (frame_time, afr);
+		if (_frame_interval_checker->guess() == FrameIntervalChecker::PROBABLY_NOT_3D && vft == VIDEO_FRAME_TYPE_3D) {
+			boost::throw_exception (
+				DecodeError(
+					String::compose(
+						_("The content file %1 is set as 3D but does not appear to contain 3D images.  Please set it to 2D.  "
+						  "You can still make a 3D DCP from this content by ticking the 3D option in the DCP video tab."),
+						_content->path(0)
 						)
-					);
-			}
+					)
+				);
 		}
-	}
 
-	double const afr = _content->active_video_frame_rate(film);
+		if (_frame_interval_checker->guess() != FrameIntervalChecker::AGAIN) {
+			_frame_interval_checker.reset ();
+		}
+	}
 
 	Frame frame;
 	Eyes eyes = EYES_BOTH;
@@ -100,15 +102,14 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 		   If we drop the frame with the duplicated timestamp we obviously lose sync.
 		*/
 		_position = ContentTime::from_frames (decoder_frame, afr);
-		if (_content->video->frame_type() == VIDEO_FRAME_TYPE_3D_ALTERNATE) {
+		if (vft == VIDEO_FRAME_TYPE_3D_ALTERNATE) {
 			frame = decoder_frame / 2;
 			_last_emitted_eyes = EYES_RIGHT;
 		} else {
 			frame = decoder_frame;
 		}
 	} else {
-		VideoFrameType const ft = _content->video->frame_type ();
-		if (ft == VIDEO_FRAME_TYPE_3D_ALTERNATE || ft == VIDEO_FRAME_TYPE_3D) {
+		if (vft == VIDEO_FRAME_TYPE_3D || vft == VIDEO_FRAME_TYPE_3D_ALTERNATE) {
 			DCPOMATIC_ASSERT (_last_emitted_eyes);
 			if (_last_emitted_eyes.get() == EYES_RIGHT) {
 				frame = _position->frames_round(afr) + 1;
@@ -122,7 +123,7 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 		}
 	}
 
-	switch (_content->video->frame_type ()) {
+	switch (vft) {
 	case VIDEO_FRAME_TYPE_2D:
 		Data (ContentVideo (image, frame, EYES_BOTH, PART_WHOLE));
 		break;
@@ -163,7 +164,8 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 void
 VideoDecoder::seek ()
 {
-	_position = boost::optional<ContentTime>();
+	_position = boost::none;
 	_last_emitted_frame.reset ();
 	_last_emitted_eyes.reset ();
+	_frame_interval_checker.reset (new FrameIntervalChecker());
 }
diff --git a/src/lib/video_decoder.h b/src/lib/video_decoder.h
index c8530d82c..dca8eef11 100644
--- a/src/lib/video_decoder.h
+++ b/src/lib/video_decoder.h
@@ -37,6 +37,7 @@ class VideoContent;
 class ImageProxy;
 class Image;
 class Log;
+class FrameIntervalChecker;
 
 /** @class VideoDecoder
  *  @brief Parent for classes which decode video.
@@ -66,7 +67,7 @@ private:
 	boost::optional<Frame> _last_emitted_frame;
 	boost::optional<Eyes> _last_emitted_eyes;
 	boost::optional<dcpomatic::ContentTime> _position;
-	std::vector<Frame> _last_threed_frames;
+	boost::scoped_ptr<FrameIntervalChecker> _frame_interval_checker;
 };
 
 #endif
diff --git a/src/lib/video_mxf_decoder.cc b/src/lib/video_mxf_decoder.cc
index 1bf2b1bef..4482606f0 100644
--- a/src/lib/video_mxf_decoder.cc
+++ b/src/lib/video_mxf_decoder.cc
@@ -22,6 +22,7 @@
 #include "video_decoder.h"
 #include "video_mxf_content.h"
 #include "j2k_image_proxy.h"
+#include "frame_interval_checker.h"
 #include <dcp/mono_picture_asset.h>
 #include <dcp/mono_picture_asset_reader.h>
 #include <dcp/stereo_picture_asset.h>
diff --git a/src/lib/wscript b/src/lib/wscript
index b78586843..31071bf7a 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -107,6 +107,7 @@ sources = """
           filter.cc
           ffmpeg_image_proxy.cc
           font.cc
+          frame_interval_checker.cc
           frame_rate_change.cc
           hints.cc
           internet.cc