Add guess_crop().

5 files changed, 238 insertions, 0 deletions

diff --git a/src/lib/guess_crop.cc b/src/lib/guess_crop.cc
new file mode 100644
index 000000000..5deb0e480
--- /dev/null
+++ b/src/lib/guess_crop.cc
@@ -0,0 +1,133 @@
+/*
+    Copyright (C) 2021 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 "decoder.h"
+#include "decoder_factory.h"
+#include "image_proxy.h"
+#include "guess_crop.h"
+#include "image.h"
+#include "video_decoder.h"
+
+
+using std::shared_ptr;
+using namespace dcpomatic;
+
+
+Crop
+guess_crop (shared_ptr<const Image> image, double threshold)
+{
+	auto const width = image->size().width;
+	auto const height = image->size().height;
+
+	auto image_in_line = [image, threshold](int start_x, int start_y, int pixels, bool rows) {
+		double brightest = 0;
+
+		switch (image->pixel_format()) {
+		case AV_PIX_FMT_RGB24:
+		{
+			uint8_t const* data = image->data()[0] + start_x * 3 + start_y * image->stride()[0];
+			for (int p = 0; p < pixels; ++p) {
+				/* Averaging R, G and B */
+				brightest = std::max(brightest, static_cast<double>(data[0] + data[1] + data[2]) / (3 * 256));
+				data += rows ? 3 : image->stride()[0];
+			}
+			break;
+		}
+		case AV_PIX_FMT_YUV420P:
+		{
+			uint8_t const* data = image->data()[0] + start_x + start_y * image->stride()[0];
+			for (int p = 0; p < pixels; ++p) {
+				/* Just using Y */
+				brightest = std::max(brightest, static_cast<double>(*data) / 256);
+				data += rows ? 1 : image->stride()[0];
+			}
+			break;
+		}
+		default:
+			DCPOMATIC_ASSERT (false);
+		}
+
+		return brightest > threshold;
+	};
+
+	auto crop = Crop{};
+
+	for (auto y = 0; y < height; ++y) {
+		if (image_in_line(0, y, width, true)) {
+			crop.top = y;
+			break;
+		}
+	}
+
+	for (auto y = height - 1; y >= 0; --y) {
+		if (image_in_line(0, y, width, true)) {
+			crop.bottom = height - 1 - y;
+			break;
+		}
+	}
+
+	for (auto x = 0; x < width; ++x) {
+		if (image_in_line(x, 0, height, false)) {
+			crop.left = x;
+			break;
+		}
+	}
+
+	for (auto x = width - 1; x >= 0; --x) {
+		if (image_in_line(x, 0, height, false)) {
+			crop.right = width - 1 - x;
+			break;
+		}
+	}
+
+	return crop;
+}
+
+
+/** @param position Time within the content to get a video frame from when guessing the crop */
+Crop
+guess_crop (shared_ptr<const Film> film, shared_ptr<const Content> content, double threshold, ContentTime position)
+{
+	DCPOMATIC_ASSERT (content->video);
+
+	auto decoder = decoder_factory (film, content, false, false, {});
+	DCPOMATIC_ASSERT (decoder->video);
+
+	bool done = false;
+	auto crop = Crop{};
+
+	auto handle_video = [&done, &crop, threshold](ContentVideo video) {
+		crop = guess_crop(video.image->image(Image::Alignment::COMPACT).image, threshold);
+		done = true;
+	};
+
+	decoder->video->Data.connect (handle_video);
+	decoder->seek (position, false);
+
+	int tries_left = 50;
+	while (!done && tries_left >= 0) {
+		decoder->pass();
+		--tries_left;
+	}
+
+	return crop;
+}
+
diff --git a/src/lib/guess_crop.h b/src/lib/guess_crop.h
new file mode 100644
index 000000000..d74912042
--- /dev/null
+++ b/src/lib/guess_crop.h
@@ -0,0 +1,34 @@
+/*
+    Copyright (C) 2021 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 "types.h"
+#include <memory>
+
+
+class Content;
+class Film;
+class Image;
+
+
+Crop guess_crop (std::shared_ptr<const Image> image, double threshold);
+Crop guess_crop (std::shared_ptr<const Film> fillm, std::shared_ptr<const Content> content, double threshold, dcpomatic::ContentTime position);
+
diff --git a/src/lib/wscript b/src/lib/wscript
index a5f96ec82..871365766 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -116,6 +116,7 @@ sources = """
           font_data.cc
           frame_interval_checker.cc
           frame_rate_change.cc
+          guess_crop.cc
           hints.cc
           internet.cc
           image.cc
diff --git a/test/guess_crop_test.cc b/test/guess_crop_test.cc
new file mode 100644
index 000000000..c26fc5ee4
--- /dev/null
+++ b/test/guess_crop_test.cc
@@ -0,0 +1,69 @@
+/*
+    Copyright (C) 2021 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 "lib/content.h"
+#include "lib/content_factory.h"
+#include "lib/guess_crop.h"
+#include "lib/types.h"
+#include "lib/video_content.h"
+#include "test.h"
+#include <boost/test/unit_test.hpp>
+#include <iostream>
+#include <vector>
+
+
+using namespace dcpomatic;
+
+
+BOOST_AUTO_TEST_CASE (guess_crop_image_test1)
+{
+	auto content = content_factory(TestPaths::private_data() / "arrietty_724.tiff").front();
+	auto film = new_test_film2 ("guess_crop_image_test1", { content });
+
+	BOOST_CHECK (
+		guess_crop(film, content, 0.1, ContentTime::from_frames(content->video->length(), content->video_frame_rate().get()))
+		== Crop(0, 0, 11, 11)
+		);
+}
+
+
+BOOST_AUTO_TEST_CASE (guess_crop_image_test2)
+{
+	auto content = content_factory(TestPaths::private_data() / "prophet_frame.tiff").front();
+	auto film = new_test_film2 ("guess_crop_image_test2", { content });
+
+	BOOST_CHECK (
+		guess_crop(film, content, 0.1, ContentTime::from_frames(content->video->length(), content->video_frame_rate().get()))
+		== Crop(0, 0, 22, 22)
+		);
+}
+
+
+BOOST_AUTO_TEST_CASE (guess_crop_image_test3)
+{
+	auto content = content_factory(TestPaths::private_data() / "pillarbox.png").front();
+	auto film = new_test_film2 ("guess_crop_image_test3", { content });
+
+	BOOST_CHECK (
+		guess_crop(film, content, 0.1, ContentTime::from_frames(content->video->length(), content->video_frame_rate().get()))
+		== Crop(113, 262, 0, 0)
+		);
+}
diff --git a/test/wscript b/test/wscript
index 1e24956bf..b8f490eca 100644
--- a/test/wscript
+++ b/test/wscript
@@ -89,6 +89,7 @@ def build(bld):
                  find_missing_test.cc
                  frame_interval_checker_test.cc
                  frame_rate_test.cc
+                 guess_crop_test.cc
                  hints_test.cc
                  image_content_fade_test.cc
                  image_filename_sorter_test.cc