From 3dcabe8d9c7d82f6be4790fd68db62188ce64710 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Sat, 12 Apr 2025 11:32:55 +0200
Subject: Add has_alpha() flag to VideoContent.

---
 src/lib/dcp_examiner.h       | 4 ++++
 src/lib/ffmpeg_examiner.h    | 3 ++-
 src/lib/image_examiner.cc    | 4 +++-
 src/lib/image_examiner.h     | 4 ++++
 src/lib/video_content.cc     | 5 +++++
 src/lib/video_content.h      | 6 ++++++
 src/lib/video_examiner.h     | 1 +
 src/lib/video_mxf_examiner.h | 3 +++
 8 files changed, 28 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/lib/dcp_examiner.h b/src/lib/dcp_examiner.h
index 381afdaed..ca3cae76e 100644
--- a/src/lib/dcp_examiner.h
+++ b/src/lib/dcp_examiner.h
@@ -68,6 +68,10 @@ public:
 		return {};
 	}
 
+	bool has_alpha() const override {
+		return false;
+	}
+
 	std::string name() const {
 		return _name;
 	}
diff --git a/src/lib/ffmpeg_examiner.h b/src/lib/ffmpeg_examiner.h
index ad64f349d..c85a76d40 100644
--- a/src/lib/ffmpeg_examiner.h
+++ b/src/lib/ffmpeg_examiner.h
@@ -59,6 +59,8 @@ public:
 
 	PixelQuanta pixel_quanta () const override;
 
+	bool has_alpha() const override;
+
 	AVColorRange color_range () const {
 		return video_codec_context()->color_range;
 	}
@@ -77,7 +79,6 @@ public:
 
 	boost::optional<int> bits_per_pixel () const;
 
-	bool has_alpha() const;
 
 	boost::optional<double> rotation () const {
 		return _rotation;
diff --git a/src/lib/image_examiner.cc b/src/lib/image_examiner.cc
index 15a0b043d..16258aed5 100644
--- a/src/lib/image_examiner.cc
+++ b/src/lib/image_examiner.cc
@@ -66,7 +66,9 @@ ImageExaminer::ImageExaminer (shared_ptr<const Film> film, shared_ptr<const Imag
 		}
 	} else {
 		FFmpegImageProxy proxy(content->path(0));
-		_video_size = proxy.image(Image::Alignment::COMPACT).image->size();
+		auto image = proxy.image(Image::Alignment::COMPACT);
+		_video_size = image.image->size();
+		_has_alpha = image.image->has_alpha();
 	}
 
 	if (content->still ()) {
diff --git a/src/lib/image_examiner.h b/src/lib/image_examiner.h
index 54fca7ed1..d6cdfac53 100644
--- a/src/lib/image_examiner.h
+++ b/src/lib/image_examiner.h
@@ -43,10 +43,14 @@ public:
 		/* See ::yuv - we're assuming the image is not YUV and so not subsampled */
 		return {};
 	}
+	bool has_alpha() const override {
+		return _has_alpha;
+	}
 
 private:
 	std::weak_ptr<const Film> _film;
 	std::shared_ptr<const ImageContent> _image_content;
 	boost::optional<dcp::Size> _video_size;
 	Frame _video_length;
+	bool _has_alpha = false;
 };
diff --git a/src/lib/video_content.cc b/src/lib/video_content.cc
index 4203d6640..a5f65de24 100644
--- a/src/lib/video_content.cc
+++ b/src/lib/video_content.cc
@@ -199,6 +199,7 @@ VideoContent::VideoContent(Content* parent, cxml::ConstNodePtr node, int version
 		_burnt_subtitle_language = dcp::LanguageTag(*burnt);
 	}
 
+	_has_alpha = node->optional_bool_child("HasAlpha").get_value_or(false);
 }
 
 
@@ -255,6 +256,7 @@ VideoContent::VideoContent(Content* parent, vector<shared_ptr<Content> > c)
 		}
 
 		_pixel_quanta = max(_pixel_quanta, c[i]->video->_pixel_quanta);
+		_has_alpha = _has_alpha | c[i]->video->_has_alpha;
 	}
 
 	_use = ref->use();
@@ -303,6 +305,7 @@ VideoContent::as_xml(xmlpp::Element* element) const
 	if (_burnt_subtitle_language) {
 		cxml::add_text_child(element, "BurntSubtitleLanguage", _burnt_subtitle_language->as_string());
 	}
+	cxml::add_text_child(element, "HasAlpha", _has_alpha ? "1" : "0");
 }
 
 void
@@ -315,6 +318,7 @@ VideoContent::take_from_examiner(shared_ptr<const Film> film, shared_ptr<VideoEx
 	auto const yuv = d->yuv();
 	auto const range = d->range();
 	auto const pixel_quanta = d->pixel_quanta();
+	auto const has_alpha = d->has_alpha();
 
 	ContentChangeSignaller cc1(_parent, VideoContentProperty::SIZE);
 	ContentChangeSignaller cc2(_parent, ContentProperty::LENGTH);
@@ -328,6 +332,7 @@ VideoContent::take_from_examiner(shared_ptr<const Film> film, shared_ptr<VideoEx
 		_yuv = yuv;
 		_range = range;
 		_pixel_quanta = pixel_quanta;
+		_has_alpha = has_alpha;
 	}
 
 	LOG_GENERAL("Video length obtained from header as %1 frames", _length);
diff --git a/src/lib/video_content.h b/src/lib/video_content.h
index c6fce70d5..db46f06eb 100644
--- a/src/lib/video_content.h
+++ b/src/lib/video_content.h
@@ -192,6 +192,11 @@ public:
 		return _pixel_quanta;
 	}
 
+	bool has_alpha() const {
+		boost::mutex::scoped_lock lm(_mutex);
+		return _has_alpha;
+	}
+
 	bool use() const {
 		boost::mutex::scoped_lock lm(_mutex);
 		return _use;
@@ -261,6 +266,7 @@ private:
 	VideoRange _range;
 	PixelQuanta _pixel_quanta;
 	boost::optional<dcp::LanguageTag> _burnt_subtitle_language;
+	bool _has_alpha = false;
 };
 
 
diff --git a/src/lib/video_examiner.h b/src/lib/video_examiner.h
index 471537f7a..e13241885 100644
--- a/src/lib/video_examiner.h
+++ b/src/lib/video_examiner.h
@@ -53,4 +53,5 @@ public:
 	virtual bool yuv() const = 0;
 	virtual VideoRange range() const = 0;
 	virtual PixelQuanta pixel_quanta() const = 0;
+	virtual bool has_alpha() const = 0;
 };
diff --git a/src/lib/video_mxf_examiner.h b/src/lib/video_mxf_examiner.h
index e4cd98f07..2dad09c08 100644
--- a/src/lib/video_mxf_examiner.h
+++ b/src/lib/video_mxf_examiner.h
@@ -45,6 +45,9 @@ public:
 	PixelQuanta pixel_quanta () const override {
 		return {};
 	}
+	bool has_alpha() const override {
+		return false;
+	}
 
 private:
 	std::shared_ptr<dcp::PictureAsset> _asset;
-- 
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