Obey requests to change the video range of RGB content.

Video that comes in with RGB pixels will not have its video level
ranges changed by libswscale (it only does this for YUV and greyscale).
Here we add code to do it ourselves for RGB content coming in
via image files (e.g. PNG/DPX etc).  Part of #1851.

9 files changed, 103 insertions, 10 deletions

diff --git a/src/lib/ffmpeg_image_proxy.cc b/src/lib/ffmpeg_image_proxy.cc
index 602185bb8..c978fc383 100644
--- a/src/lib/ffmpeg_image_proxy.cc
+++ b/src/lib/ffmpeg_image_proxy.cc
@@ -30,6 +30,7 @@
 extern "C" {
 #include <libavcodec/avcodec.h>
 #include <libavformat/avformat.h>
+#include <libavutil/pixdesc.h>
 }
 DCPOMATIC_DISABLE_WARNINGS
 #include <libxml++/libxml++.h>
@@ -48,23 +49,26 @@ using boost::optional;
 using boost::dynamic_pointer_cast;
 using dcp::raw_convert;
 
-FFmpegImageProxy::FFmpegImageProxy (boost::filesystem::path path)
+FFmpegImageProxy::FFmpegImageProxy (boost::filesystem::path path, VideoRange video_range)
 	: _data (path)
+	, _video_range (video_range)
 	, _pos (0)
 	, _path (path)
 {
 
 }
 
-FFmpegImageProxy::FFmpegImageProxy (dcp::ArrayData data)
+FFmpegImageProxy::FFmpegImageProxy (dcp::ArrayData data, VideoRange video_range)
 	: _data (data)
+	, _video_range (video_range)
 	, _pos (0)
 {
 
 }
 
-FFmpegImageProxy::FFmpegImageProxy (shared_ptr<cxml::Node>, shared_ptr<Socket> socket)
-	: _pos (0)
+FFmpegImageProxy::FFmpegImageProxy (shared_ptr<cxml::Node> node, shared_ptr<Socket> socket)
+	: _video_range (string_to_video_range(node->string_child("VideoRange")))
+	, _pos (0)
 {
 	uint32_t const size = socket->read_uint32 ();
 	_data = dcp::ArrayData (size);
@@ -188,7 +192,16 @@ FFmpegImageProxy::image (optional<dcp::Size>) const
 		throw DecodeError (N_("could not decode video"));
 	}
 
-	_image.reset (new Image (frame));
+	AVPixelFormat const pix_fmt = static_cast<AVPixelFormat>(frame->format);
+
+	_image.reset (new Image(frame));
+	if (_video_range == VIDEO_RANGE_VIDEO && av_pix_fmt_desc_get(pix_fmt)->flags & AV_PIX_FMT_FLAG_RGB) {
+		/* Asking for the video range to be converted by libswscale (in Image) will not work for
+		 * RGB sources since that method only processes video range in YUV and greyscale.  So we have
+		 * to do it ourselves here.
+		 */
+		_image->video_range_to_full_range();
+	}
 
 	av_packet_unref (&packet);
 	av_frame_free (&frame);
@@ -206,6 +219,7 @@ void
 FFmpegImageProxy::add_metadata (xmlpp::Node* node) const
 {
 	node->add_child("Type")->add_child_text (N_("FFmpeg"));
+	node->add_child("VideoRange")->add_child_text(video_range_to_string(_video_range));
 }
 
 void
diff --git a/src/lib/ffmpeg_image_proxy.h b/src/lib/ffmpeg_image_proxy.h
index 62b99d280..4fca899f4 100644
--- a/src/lib/ffmpeg_image_proxy.h
+++ b/src/lib/ffmpeg_image_proxy.h
@@ -19,6 +19,7 @@
 */
 
 #include "image_proxy.h"
+#include "types.h"
 #include <dcp/array_data.h>
 #include <boost/thread/mutex.hpp>
 #include <boost/filesystem.hpp>
@@ -26,8 +27,8 @@
 class FFmpegImageProxy : public ImageProxy
 {
 public:
-	explicit FFmpegImageProxy (boost::filesystem::path);
-	explicit FFmpegImageProxy (dcp::ArrayData);
+	explicit FFmpegImageProxy (boost::filesystem::path, VideoRange video_range);
+	explicit FFmpegImageProxy (dcp::ArrayData, VideoRange video_range);
 	FFmpegImageProxy (boost::shared_ptr<cxml::Node> xml, boost::shared_ptr<Socket> socket);
 
 	Result image (
@@ -44,6 +45,7 @@ public:
 
 private:
 	dcp::ArrayData _data;
+	VideoRange _video_range;
 	mutable int64_t _pos;
 	/** Path of a file that this image came from, if applicable; stored so that
 	    failed-decode errors can give more detail.
diff --git a/src/lib/image.cc b/src/lib/image.cc
index 03f1bf6dc..891715a46 100644
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -1319,3 +1319,46 @@ Image::as_png () const
 
 	return dcp::ArrayData (state.data, state.size);
 }
+
+
+void
+Image::video_range_to_full_range ()
+{
+	switch (_pixel_format) {
+	case AV_PIX_FMT_RGB24:
+	{
+		float const factor = 256.0 / 219.0;
+		uint8_t* p = data()[0];
+		int const lines = sample_size(0).height;
+		for (int y = 0; y < lines; ++y) {
+			uint8_t* q = p;
+			for (int x = 0; x < line_size()[0]; ++x) {
+				*q = int((*q - 16) * factor);
+				++q;
+			}
+			p += stride()[0];
+		}
+		break;
+	}
+	case AV_PIX_FMT_GBRP12LE:
+	{
+		float const factor = 4096.0 / 3504.0;
+		for (int c = 0; c < 3; ++c) {
+			uint16_t* p = reinterpret_cast<uint16_t*>(data()[c]);
+			int const lines = sample_size(c).height;
+			for (int y = 0; y < lines; ++y) {
+				uint16_t* q = p;
+				int const line_size_pixels = line_size()[c] / 2;
+				for (int x = 0; x < line_size_pixels; ++x) {
+					*q = int((*q - 256) * factor);
+					++q;
+				}
+			}
+		}
+		break;
+	}
+	default:
+		throw PixelFormatError ("video_range_to_full_range()", _pixel_format);
+	}
+}
+
diff --git a/src/lib/image.h b/src/lib/image.h
index ab9b3c78a..c648fda1b 100644
--- a/src/lib/image.h
+++ b/src/lib/image.h
@@ -74,6 +74,7 @@ public:
 	void alpha_blend (boost::shared_ptr<const Image> image, Position<int> pos);
 	void copy (boost::shared_ptr<const Image> image, Position<int> pos);
 	void fade (float);
+	void video_range_to_full_range ();
 
 	void read_from_socket (boost::shared_ptr<Socket>);
 	void write_to_socket (boost::shared_ptr<Socket>) const;
diff --git a/src/lib/image_decoder.cc b/src/lib/image_decoder.cc
index 15187b11b..7757cc4aa 100644
--- a/src/lib/image_decoder.cc
+++ b/src/lib/image_decoder.cc
@@ -70,7 +70,7 @@ ImageDecoder::pass ()
 			*/
 			_image.reset (new J2KImageProxy (path, _image_content->video->size(), pf));
 		} else {
-			_image.reset (new FFmpegImageProxy (path));
+			_image.reset (new FFmpegImageProxy(path, _image_content->video->range()));
 		}
 	}
 
diff --git a/src/lib/image_examiner.cc b/src/lib/image_examiner.cc
index 6586a0d09..aa80d0daa 100644
--- a/src/lib/image_examiner.cc
+++ b/src/lib/image_examiner.cc
@@ -63,7 +63,7 @@ ImageExaminer::ImageExaminer (shared_ptr<const Film> film, shared_ptr<const Imag
 		}
 		delete[] buffer;
 	} else {
-		FFmpegImageProxy proxy(content->path(0));
+		FFmpegImageProxy proxy(content->path(0), content->video->range());
 		_video_size = proxy.image().image->size();
 	}
 
diff --git a/src/lib/types.cc b/src/lib/types.cc
index e7acf6992..5687a5d48 100644
--- a/src/lib/types.cc
+++ b/src/lib/types.cc
@@ -229,3 +229,31 @@ bool operator== (NamedChannel const& a, NamedChannel const& b)
 	return a.name == b.name && a.index == b.index;
 }
 
+
+string
+video_range_to_string (VideoRange r)
+{
+	switch (r) {
+	case VIDEO_RANGE_FULL:
+		return "full";
+	case VIDEO_RANGE_VIDEO:
+		return "video";
+	default:
+		DCPOMATIC_ASSERT (false);
+	}
+}
+
+
+VideoRange
+string_to_video_range (string s)
+{
+	if (s == "full") {
+		return VIDEO_RANGE_FULL;
+	} else if (s == "video") {
+		return VIDEO_RANGE_VIDEO;
+	}
+
+	DCPOMATIC_ASSERT (false);
+	return VIDEO_RANGE_FULL;
+}
+
diff --git a/src/lib/types.h b/src/lib/types.h
index 2ba0408ad..a10b26a63 100644
--- a/src/lib/types.h
+++ b/src/lib/types.h
@@ -139,12 +139,17 @@ enum ChangeType
 	CHANGE_TYPE_CANCELLED
 };
 
+
 enum VideoRange
 {
 	VIDEO_RANGE_FULL, ///< full,  or "JPEG" (0-255 for 8-bit)
 	VIDEO_RANGE_VIDEO ///< video, or "MPEG" (16-235 for 8-bit)
 };
 
+extern std::string video_range_to_string (VideoRange r);
+extern VideoRange string_to_video_range (std::string s);
+
+
 /** Type of captions.
  *
  *  The generally accepted definitions seem to be:
diff --git a/src/lib/util.cc b/src/lib/util.cc
index ac868c173..0a060e960 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -953,7 +953,7 @@ void
 emit_subtitle_image (ContentTimePeriod period, dcp::SubtitleImage sub, dcp::Size size, shared_ptr<TextDecoder> decoder)
 {
 	/* XXX: this is rather inefficient; decoding the image just to get its size */
-	FFmpegImageProxy proxy (sub.png_image());
+	FFmpegImageProxy proxy (sub.png_image(), VIDEO_RANGE_FULL);
 	shared_ptr<Image> image = proxy.image().image;
 	/* set up rect with height and width */
 	dcpomatic::Rect<double> rect(0, 0, image->size().width / double(size.width), image->size().height / double(size.height));