Switch subtitle string font specs to be the font ID; split SubtitleContent into Interop and SMPTE.

14 files changed, 424 insertions, 234 deletions

diff --git a/src/dcp.cc b/src/dcp.cc
index 58b6c66f..b1443e1a 100644
--- a/src/dcp.cc
+++ b/src/dcp.cc
@@ -25,7 +25,8 @@
 #include "dcp.h"
 #include "sound_mxf.h"
 #include "picture_mxf.h"
-#include "subtitle_content.h"
+#include "interop_subtitle_content.h"
+#include "smpte_subtitle_content.h"
 #include "mono_picture_mxf.h"
 #include "stereo_picture_mxf.h"
 #include "util.h"
@@ -132,7 +133,7 @@ DCP::read (bool keep_going, ReadErrors* errors)
 			if (root == "CompositionPlaylist") {
 				_assets.push_back (shared_ptr<CPL> (new CPL (path)));
 			} else if (root == "DCSubtitle") {
-				_assets.push_back (shared_ptr<SubtitleContent> (new SubtitleContent (path, false)));
+				_assets.push_back (shared_ptr<InteropSubtitleContent> (new InteropSubtitleContent (path)));
 			}
 		} else if (boost::algorithm::ends_with (path.string(), ".mxf")) {
 			ASDCP::EssenceType_t type;
@@ -154,7 +155,7 @@ DCP::read (bool keep_going, ReadErrors* errors)
 					_assets.push_back (shared_ptr<StereoPictureMXF> (new StereoPictureMXF (path)));
 					break;
 				case ASDCP::ESS_TIMED_TEXT:
-					_assets.push_back (shared_ptr<SubtitleContent> (new SubtitleContent (path, true)));
+					_assets.push_back (shared_ptr<SMPTESubtitleContent> (new SMPTESubtitleContent (path)));
 					break;
 				default:
 					throw DCPReadError ("Unknown MXF essence type");
diff --git a/src/load_font.cc b/src/interop_load_font.cc
index b46569c8..ec2653ef 100644
--- a/src/load_font.cc
+++ b/src/interop_load_font.cc
@@ -17,7 +17,7 @@
 
 */
 
-#include "load_font.h"
+#include "interop_load_font.h"
 #include <libcxml/cxml.h>
 
 using std::string;
@@ -25,7 +25,7 @@ using boost::shared_ptr;
 using boost::optional;
 using namespace dcp;
 
-LoadFont::LoadFont (boost::shared_ptr<const cxml::Node> node)
+InteropLoadFont::InteropLoadFont (shared_ptr<const cxml::Node> node)
 {
 	optional<string> x = node->optional_string_attribute ("Id");
 	if (!x) {
@@ -33,5 +33,5 @@ LoadFont::LoadFont (boost::shared_ptr<const cxml::Node> node)
 	}
 	id = x.get_value_or ("");
 	
-	uri = node->optional_string_attribute ("URI");
+	uri = node->string_attribute ("URI");
 }
diff --git a/src/interop_load_font.h b/src/interop_load_font.h
new file mode 100644
index 00000000..b6043bd0
--- /dev/null
+++ b/src/interop_load_font.h
@@ -0,0 +1,39 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include <boost/shared_ptr.hpp>
+#include <boost/optional.hpp>
+
+namespace cxml {
+	class Node;
+}
+
+namespace dcp {
+	
+class InteropLoadFont 
+{
+public:
+	InteropLoadFont () {}
+	InteropLoadFont (boost::shared_ptr<const cxml::Node> node);
+
+	std::string id;
+	std::string uri;
+};
+
+}
diff --git a/src/interop_subtitle_content.cc b/src/interop_subtitle_content.cc
new file mode 100644
index 00000000..85e52da7
--- /dev/null
+++ b/src/interop_subtitle_content.cc
@@ -0,0 +1,170 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "interop_subtitle_content.h"
+#include "interop_load_font.h"
+#include "xml.h"
+#include "raw_convert.h"
+#include "font.h"
+
+using std::list;
+using std::string;
+using boost::shared_ptr;
+using namespace dcp;
+
+InteropSubtitleContent::InteropSubtitleContent (boost::filesystem::path file)
+	: SubtitleContent (file)
+{
+	shared_ptr<cxml::Document> xml (new cxml::Document ("DCSubtitle"));
+	xml->read_file (file);
+	_id = xml->string_child ("SubtitleID");
+
+	_movie_title = xml->string_child ("MovieTitle");
+
+	_load_font_nodes = type_children<dcp::InteropLoadFont> (xml, "LoadFont");
+	list<shared_ptr<dcp::Font> > font_nodes = type_children<dcp::Font> (xml, "Font");
+
+	parse_common (xml, font_nodes);
+}
+
+InteropSubtitleContent::InteropSubtitleContent (string movie_title, string language)
+	: _movie_title (movie_title)
+{
+	_language = language;
+}
+
+struct SubtitleSorter {
+	bool operator() (SubtitleString const & a, SubtitleString const & b) {
+		if (a.in() != b.in()) {
+			return a.in() < b.in();
+		}
+		return a.v_position() < b.v_position();
+	}
+};
+
+Glib::ustring
+InteropSubtitleContent::xml_as_string () const
+{
+	xmlpp::Document doc;
+	xmlpp::Element* root = doc.create_root_node ("DCSubtitle");
+	root->set_attribute ("Version", "1.0");
+
+	root->add_child("SubtitleID")->add_child_text (_id);
+	root->add_child("MovieTitle")->add_child_text (_movie_title);
+	root->add_child("ReelNumber")->add_child_text (raw_convert<string> (_reel_number));
+	root->add_child("Language")->add_child_text (_language);
+
+	if (_load_font_nodes.size() > 1) {
+		boost::throw_exception (MiscError ("multiple LoadFont nodes not supported"));
+	}
+
+	if (!_load_font_nodes.empty ()) {
+		xmlpp::Element* load_font = root->add_child("LoadFont");
+		load_font->set_attribute ("Id", _load_font_nodes.front()->id);
+		load_font->set_attribute ("URI", _load_font_nodes.front()->uri);
+	}
+
+	list<SubtitleString> sorted = _subtitles;
+	sorted.sort (SubtitleSorter ());
+
+	/* XXX: multiple fonts not supported */
+	/* XXX: script, underlined, weight not supported */
+
+	bool italic = false;
+	Color color;
+	int size = 0;
+	Effect effect = NONE;
+	Color effect_color;
+	int spot_number = 1;
+	Time last_in;
+	Time last_out;
+	Time last_fade_up_time;
+	Time last_fade_down_time;
+
+	xmlpp::Element* font = 0;
+	xmlpp::Element* subtitle = 0;
+
+	for (list<SubtitleString>::iterator i = sorted.begin(); i != sorted.end(); ++i) {
+
+		/* We will start a new <Font>...</Font> whenever some font property changes.
+		   I suppose we should really make an optimal hierarchy of <Font> tags, but
+		   that seems hard.
+		*/
+
+		bool const font_changed =
+			italic       != i->italic()       ||
+			color        != i->color()        ||
+			size         != i->size()         ||
+			effect       != i->effect()       ||
+			effect_color != i->effect_color();
+
+		if (font_changed) {
+			italic = i->italic ();
+			color = i->color ();
+			size = i->size ();
+			effect = i->effect ();
+			effect_color = i->effect_color ();
+		}
+
+		if (!font || font_changed) {
+			font = root->add_child ("Font");
+			string id = "theFontId";
+			if (!_load_font_nodes.empty()) {
+				id = _load_font_nodes.front()->id;
+			}
+			font->set_attribute ("Id", id);
+			font->set_attribute ("Italic", italic ? "yes" : "no");
+			font->set_attribute ("Color", color.to_argb_string());
+			font->set_attribute ("Size", raw_convert<string> (size));
+			font->set_attribute ("Effect", effect_to_string (effect));
+			font->set_attribute ("EffectColor", effect_color.to_argb_string());
+			font->set_attribute ("Script", "normal");
+			font->set_attribute ("Underlined", "no");
+			font->set_attribute ("Weight", "normal");
+		}
+
+		if (!subtitle || font_changed ||
+		    (last_in != i->in() ||
+		     last_out != i->out() ||
+		     last_fade_up_time != i->fade_up_time() ||
+		     last_fade_down_time != i->fade_down_time()
+			    )) {
+
+			subtitle = font->add_child ("Subtitle");
+			subtitle->set_attribute ("SpotNumber", raw_convert<string> (spot_number++));
+			subtitle->set_attribute ("TimeIn", i->in().to_string());
+			subtitle->set_attribute ("TimeOut", i->out().to_string());
+			subtitle->set_attribute ("FadeUpTime", raw_convert<string> (i->fade_up_time().to_ticks()));
+			subtitle->set_attribute ("FadeDownTime", raw_convert<string> (i->fade_down_time().to_ticks()));
+
+			last_in = i->in ();
+			last_out = i->out ();
+			last_fade_up_time = i->fade_up_time ();
+			last_fade_down_time = i->fade_down_time ();
+		}
+
+		xmlpp::Element* text = subtitle->add_child ("Text");
+		text->set_attribute ("VAlign", valign_to_string (i->v_align()));		
+		text->set_attribute ("VPosition", raw_convert<string> (i->v_position()));
+		text->add_child_text (i->text());
+	}
+
+	return doc.write_to_string_formatted ("UTF-8");
+}
+
diff --git a/src/interop_subtitle_content.h b/src/interop_subtitle_content.h
new file mode 100644
index 00000000..cd8d7bbd
--- /dev/null
+++ b/src/interop_subtitle_content.h
@@ -0,0 +1,40 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "subtitle_content.h"
+#include <boost/filesystem.hpp>
+
+namespace dcp {
+
+class InteropLoadFont;	
+
+class InteropSubtitleContent : public SubtitleContent
+{
+public:
+	InteropSubtitleContent (std::string movie_title, std::string language);
+	InteropSubtitleContent (boost::filesystem::path file);
+
+	Glib::ustring xml_as_string () const;
+	
+private:
+	std::string _movie_title;
+	std::list<boost::shared_ptr<InteropLoadFont> > _load_font_nodes;
+};
+
+}
diff --git a/src/smpte_load_font.cc b/src/smpte_load_font.cc
new file mode 100644
index 00000000..90e9c993
--- /dev/null
+++ b/src/smpte_load_font.cc
@@ -0,0 +1,31 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "smpte_load_font.h"
+#include <libcxml/cxml.h>
+
+using std::string;
+using boost::shared_ptr;
+using namespace dcp;
+
+SMPTELoadFont::SMPTELoadFont (shared_ptr<const cxml::Node> node)
+{
+	id = node->string_attribute ("ID");
+	urn = node->content().substr (9);
+}
diff --git a/src/load_font.h b/src/smpte_load_font.h
index 6d52a509..d8d1fa66 100644
--- a/src/load_font.h
+++ b/src/smpte_load_font.h
@@ -26,14 +26,14 @@ namespace cxml {
 
 namespace dcp {
 	
-class LoadFont 
+class SMPTELoadFont 
 {
 public:
-	LoadFont () {}
-	LoadFont (boost::shared_ptr<const cxml::Node> node);
+	SMPTELoadFont () {}
+	SMPTELoadFont (boost::shared_ptr<const cxml::Node> node);
 
 	std::string id;
-	boost::optional<std::string> uri;
+	std::string urn;
 };
 
 }
diff --git a/src/smpte_subtitle_content.cc b/src/smpte_subtitle_content.cc
new file mode 100644
index 00000000..1fa94d1c
--- /dev/null
+++ b/src/smpte_subtitle_content.cc
@@ -0,0 +1,63 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "smpte_subtitle_content.h"
+#include "smpte_load_font.h"
+#include "font.h"
+#include "exceptions.h"
+#include "xml.h"
+#include "AS_DCP.h"
+#include "KM_util.h"
+
+using std::string;
+using std::list;
+using std::stringstream;
+using boost::shared_ptr;
+using namespace dcp;
+
+SMPTESubtitleContent::SMPTESubtitleContent (boost::filesystem::path file)
+	: SubtitleContent (file)
+{
+	ASDCP::TimedText::MXFReader reader;
+	Kumu::Result_t r = reader.OpenRead (file.string().c_str ());
+	if (ASDCP_FAILURE (r)) {
+		boost::throw_exception (MXFFileError ("could not open MXF file for reading", file, r));
+	}
+	
+	string s;
+	reader.ReadTimedTextResource (s, 0, 0);
+	shared_ptr<cxml::Document> xml (new cxml::Document ("SubtitleReel"));
+	stringstream t;
+	t << s;
+	xml->read_stream (t);
+	
+	ASDCP::WriterInfo info;
+	reader.FillWriterInfo (info);
+	
+	char buffer[64];
+	Kumu::bin2UUIDhex (info.AssetUUID, ASDCP::UUIDlen, buffer, sizeof (buffer));
+	_id = buffer;
+
+	_load_font_nodes = type_children<dcp::SMPTELoadFont> (xml, "LoadFont");
+
+	shared_ptr<cxml::Node> subtitle_list = xml->optional_node_child ("SubtitleList");
+	list<shared_ptr<dcp::Font> > font_nodes = type_children<dcp::Font> (subtitle_list, "Font");
+
+	parse_common (xml, font_nodes);
+}
diff --git a/src/smpte_subtitle_content.h b/src/smpte_subtitle_content.h
new file mode 100644
index 00000000..b760f727
--- /dev/null
+++ b/src/smpte_subtitle_content.h
@@ -0,0 +1,36 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program 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.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "subtitle_content.h"
+
+namespace dcp {
+
+class SMPTELoadFont;	
+
+class SMPTESubtitleContent : public SubtitleContent
+{
+public:
+	/** @param file MXF file */
+	SMPTESubtitleContent (boost::filesystem::path file);
+
+private:
+	std::list<boost::shared_ptr<SMPTELoadFont> > _load_font_nodes;
+};
+
+}
diff --git a/src/subtitle_content.cc b/src/subtitle_content.cc
index 4f83d5bd..7bc080b3 100644
--- a/src/subtitle_content.cc
+++ b/src/subtitle_content.cc
@@ -23,7 +23,6 @@
 #include "xml.h"
 #include "font.h"
 #include "text.h"
-#include "load_font.h"
 #include "subtitle_string.h"
 #include "AS_DCP.h"
 #include "KM_util.h"
@@ -41,71 +40,26 @@ using boost::shared_ptr;
 using boost::optional;
 using namespace dcp;
 
-SubtitleContent::SubtitleContent (boost::filesystem::path file, bool mxf)
+SubtitleContent::SubtitleContent (boost::filesystem::path file)
 	: Content (file)
 {
-	shared_ptr<cxml::Document> xml;
-	
-	if (mxf) {
-		ASDCP::TimedText::MXFReader reader;
-		Kumu::Result_t r = reader.OpenRead (file.string().c_str ());
-		if (ASDCP_FAILURE (r)) {
-			boost::throw_exception (MXFFileError ("could not open MXF file for reading", file, r));
-		}
-		
-		string s;
-		reader.ReadTimedTextResource (s, 0, 0);
-		xml.reset (new cxml::Document ("SubtitleReel"));
-		stringstream t;
-		t << s;
-		xml->read_stream (t);
-
-		ASDCP::WriterInfo info;
-		reader.FillWriterInfo (info);
-		
-		char buffer[64];
-		Kumu::bin2UUIDhex (info.AssetUUID, ASDCP::UUIDlen, buffer, sizeof (buffer));
-		_id = buffer;
-
-	} else {
-		xml.reset (new cxml::Document ("DCSubtitle"));
-		xml->read_file (file);
-		_id = xml->string_child ("SubtitleID");
-	}
 
-	/* XXX: hacks aplenty in here; probably need separate parsers for DCSubtitle and SubtitleReel */
+}
 
-	_movie_title = xml->optional_string_child ("MovieTitle");
+void
+SubtitleContent::parse_common (shared_ptr<cxml::Document> xml, list<shared_ptr<dcp::Font> > font_nodes)
+{
 	_reel_number = xml->string_child ("ReelNumber");
 	_language = xml->string_child ("Language");
 
-	xml->ignore_child ("LoadFont");
-
-	list<shared_ptr<dcp::Font> > font_nodes = type_children<dcp::Font> (xml, "Font");
-	_load_font_nodes = type_children<dcp::LoadFont> (xml, "LoadFont");
-
 	/* Now make Subtitle objects to represent the raw XML nodes
 	   in a sane way.
 	*/
 
-	shared_ptr<cxml::Node> subtitle_list = xml->optional_node_child ("SubtitleList");
-	if (subtitle_list) {
-		list<shared_ptr<dcp::Font> > font = type_children<dcp::Font> (subtitle_list, "Font");
-		copy (font.begin(), font.end(), back_inserter (font_nodes));
-	}
-	
 	ParseState parse_state;
 	examine_font_nodes (xml, font_nodes, parse_state);
 }
 
-SubtitleContent::SubtitleContent (string movie_title, string language)
-	: _movie_title (movie_title)
-	, _reel_number ("1")
-	, _language (language)
-{
-
-}
-
 void
 SubtitleContent::examine_font_nodes (
 	shared_ptr<const cxml::Node> xml,
@@ -167,7 +121,7 @@ SubtitleContent::maybe_add_subtitle (string text, ParseState const & parse_state
 
 	_subtitles.push_back (
 		SubtitleString (
-			font_id_to_name (effective_font.id),
+			effective_font.id,
 			effective_font.italic.get(),
 			effective_font.color.get(),
 			effective_font.size,
@@ -197,40 +151,12 @@ SubtitleContent::subtitles_at (Time t) const
 	return s;
 }
 
-std::string
-SubtitleContent::font_id_to_name (string id) const
-{
-	list<shared_ptr<dcp::LoadFont> >::const_iterator i = _load_font_nodes.begin();
-	while (i != _load_font_nodes.end() && (*i)->id != id) {
-		++i;
-	}
-
-	if (i == _load_font_nodes.end ()) {
-		return "";
-	}
-
-	if ((*i)->uri && (*i)->uri.get() == "arial.ttf") {
-		return "Arial";
-	}
-
-	return "";
-}
-
 void
 SubtitleContent::add (SubtitleString s)
 {
 	_subtitles.push_back (s);
 }
 
-struct SubtitleSorter {
-	bool operator() (SubtitleString const & a, SubtitleString const & b) {
-		if (a.in() != b.in()) {
-			return a.in() < b.in();
-		}
-		return a.v_position() < b.v_position();
-	}
-};
-
 void
 SubtitleContent::write_xml (boost::filesystem::path p) const
 {
@@ -246,120 +172,6 @@ SubtitleContent::write_xml (boost::filesystem::path p) const
 	_file = p;
 }
 
-Glib::ustring
-SubtitleContent::xml_as_string () const
-{
-	xmlpp::Document doc;
-	xmlpp::Element* root = doc.create_root_node ("DCSubtitle");
-	root->set_attribute ("Version", "1.0");
-
-	root->add_child("SubtitleID")->add_child_text (_id);
-	if (_movie_title) {
-		root->add_child("MovieTitle")->add_child_text (_movie_title.get ());
-	}
-	root->add_child("ReelNumber")->add_child_text (raw_convert<string> (_reel_number));
-	root->add_child("Language")->add_child_text (_language);
-
-	if (_load_font_nodes.size() > 1) {
-		boost::throw_exception (MiscError ("multiple LoadFont nodes not supported"));
-	}
-
-	if (!_load_font_nodes.empty ()) {
-		xmlpp::Element* load_font = root->add_child("LoadFont");
-		load_font->set_attribute ("Id", _load_font_nodes.front()->id);
-		if (_load_font_nodes.front()->uri) {
-			load_font->set_attribute ("URI", _load_font_nodes.front()->uri.get ());
-		}
-	}
-
-	list<SubtitleString> sorted = _subtitles;
-	sorted.sort (SubtitleSorter ());
-
-	/* XXX: multiple fonts not supported */
-	/* XXX: script, underlined, weight not supported */
-
-	bool italic = false;
-	Color color;
-	int size = 0;
-	Effect effect = NONE;
-	Color effect_color;
-	int spot_number = 1;
-	Time last_in;
-	Time last_out;
-	Time last_fade_up_time;
-	Time last_fade_down_time;
-
-	xmlpp::Element* font = 0;
-	xmlpp::Element* subtitle = 0;
-
-	for (list<SubtitleString>::iterator i = sorted.begin(); i != sorted.end(); ++i) {
-
-		/* We will start a new <Font>...</Font> whenever some font property changes.
-		   I suppose we should really make an optimal hierarchy of <Font> tags, but
-		   that seems hard.
-		*/
-
-		bool const font_changed =
-			italic       != i->italic()       ||
-			color        != i->color()        ||
-			size         != i->size()         ||
-			effect       != i->effect()       ||
-			effect_color != i->effect_color();
-
-		if (font_changed) {
-			italic = i->italic ();
-			color = i->color ();
-			size = i->size ();
-			effect = i->effect ();
-			effect_color = i->effect_color ();
-		}
-
-		if (!font || font_changed) {
-			font = root->add_child ("Font");
-			string id = "theFontId";
-			if (!_load_font_nodes.empty()) {
-				id = _load_font_nodes.front()->id;
-			}
-			font->set_attribute ("Id", id);
-			font->set_attribute ("Italic", italic ? "yes" : "no");
-			font->set_attribute ("Color", color.to_argb_string());
-			font->set_attribute ("Size", raw_convert<string> (size));
-			font->set_attribute ("Effect", effect_to_string (effect));
-			font->set_attribute ("EffectColor", effect_color.to_argb_string());
-			font->set_attribute ("Script", "normal");
-			font->set_attribute ("Underlined", "no");
-			font->set_attribute ("Weight", "normal");
-		}
-
-		if (!subtitle || font_changed ||
-		    (last_in != i->in() ||
-		     last_out != i->out() ||
-		     last_fade_up_time != i->fade_up_time() ||
-		     last_fade_down_time != i->fade_down_time()
-			    )) {
-
-			subtitle = font->add_child ("Subtitle");
-			subtitle->set_attribute ("SpotNumber", raw_convert<string> (spot_number++));
-			subtitle->set_attribute ("TimeIn", i->in().to_string());
-			subtitle->set_attribute ("TimeOut", i->out().to_string());
-			subtitle->set_attribute ("FadeUpTime", raw_convert<string> (i->fade_up_time().to_ticks()));
-			subtitle->set_attribute ("FadeDownTime", raw_convert<string> (i->fade_down_time().to_ticks()));
-
-			last_in = i->in ();
-			last_out = i->out ();
-			last_fade_up_time = i->fade_up_time ();
-			last_fade_down_time = i->fade_down_time ();
-		}
-
-		xmlpp::Element* text = subtitle->add_child ("Text");
-		text->set_attribute ("VAlign", valign_to_string (i->v_align()));		
-		text->set_attribute ("VPosition", raw_convert<string> (i->v_position()));
-		text->add_child_text (i->text());
-	}
-
-	return doc.write_to_string_formatted ("UTF-8");
-}
-
 Time
 SubtitleContent::latest_subtitle_out () const
 {
diff --git a/src/subtitle_content.h b/src/subtitle_content.h
index 945eb4d0..222d52cc 100644
--- a/src/subtitle_content.h
+++ b/src/subtitle_content.h
@@ -32,23 +32,15 @@ class SubtitleString;
 class Font;
 class Text;
 class Subtitle;
-class LoadFont;
 
 /** @class SubtitleContent
- *  @brief A representation of an XML or MXF file containing subtitles.
- *
- *  XXX: perhaps this should inhert from MXF, or there should be different
- *  classes for XML and MXF subs.
+ *  @brief A parent for classes representing a file containing subtitles.
  */
 class SubtitleContent : public Content
 {
 public:
-	/** Construct a SubtitleContent.
-	 *  @param file Filename.
-	 *  @param mxf true if the file is an MXF file, false for XML.
-	 */
-	SubtitleContent (boost::filesystem::path file, bool mxf);
-	SubtitleContent (std::string movie_title, std::string language);
+	SubtitleContent () {}
+	SubtitleContent (boost::filesystem::path file);
 
 	bool equals (
 		boost::shared_ptr<const Asset>,
@@ -72,11 +64,16 @@ public:
 	void add (SubtitleString);
 
 	void write_xml (boost::filesystem::path) const;
-	Glib::ustring xml_as_string () const;
+	virtual Glib::ustring xml_as_string () const {
+		/* XXX: this should be pure virtual when SMPTE writing is implemented */
+		return "";
+	}
 
 	Time latest_subtitle_out () const;
 
 protected:
+	void parse_common (boost::shared_ptr<cxml::Document> xml, std::list<boost::shared_ptr<dcp::Font> > font_nodes);
+	
 	std::string pkl_type (Standard) const {
 		return "text/xml";
 	}
@@ -85,9 +82,13 @@ protected:
 		return "Subtitle";
 	}
 	
-private:
-	std::string font_id_to_name (std::string id) const;
+	/* strangely, this is sometimes a string */
+	std::string _reel_number;
+	std::string _language;
+
+	std::list<SubtitleString> _subtitles;
 
+private:
 	struct ParseState {
 		std::list<boost::shared_ptr<Font> > font_nodes;
 		std::list<boost::shared_ptr<Text> > text_nodes;
@@ -107,14 +108,6 @@ private:
 		std::list<boost::shared_ptr<Text> > const & text_nodes,
 		ParseState& parse_state
 		);
-
-	boost::optional<std::string> _movie_title;
-	/* strangely, this is sometimes a string */
-	std::string _reel_number;
-	std::string _language;
-	std::list<boost::shared_ptr<LoadFont> > _load_font_nodes;
-
-	std::list<SubtitleString> _subtitles;
 };
 
 }
diff --git a/src/subtitle_string.cc b/src/subtitle_string.cc
index 66869fd5..a92eac92 100644
--- a/src/subtitle_string.cc
+++ b/src/subtitle_string.cc
@@ -22,10 +22,11 @@
 
 using std::string;
 using std::ostream;
+using boost::optional;
 using namespace dcp;
 
 SubtitleString::SubtitleString (
-	string font,
+	optional<string> font,
 	bool italic,
 	Color color,
 	int size,
@@ -92,7 +93,7 @@ dcp::operator<< (ostream& s, SubtitleString const & sub)
 {
 	s << "\n`" << sub.text() << "' from " << sub.in() << " to " << sub.out() << ";\n"
 	  << "fade up " << sub.fade_up_time() << ", fade down " << sub.fade_down_time() << ";\n"
-	  << "font " << sub.font() << ", ";
+	  << "font " << sub.font().get_value_or ("[default]") << ", ";
 
 	if (sub.italic()) {
 		s << "italic";
diff --git a/src/subtitle_string.h b/src/subtitle_string.h
index b313e82b..512a1b5b 100644
--- a/src/subtitle_string.h
+++ b/src/subtitle_string.h
@@ -26,6 +26,7 @@
 
 #include "types.h"
 #include "dcp_time.h"
+#include <boost/optional.hpp>
 #include <string>
 
 namespace dcp {
@@ -37,7 +38,7 @@ class SubtitleString
 {
 public:
 	SubtitleString (
-		std::string font,
+		boost::optional<std::string> font,
 		bool italic,
 		Color color,
 		int size,
@@ -52,8 +53,8 @@ public:
 		Time fade_down_time
 		);
 
-	/** @return font name */
-	std::string font () const {
+	/** @return font ID */
+	boost::optional<std::string> font () const {
 		return _font;
 	}
 
@@ -122,8 +123,8 @@ public:
 	}
 
 private:
-	/** font name */
-	std::string _font;
+	/** font ID */
+	boost::optional<std::string> _font;
 	/** true if the text is italic */
 	bool _italic;
 	/** text colour */
diff --git a/src/wscript b/src/wscript
index 6145a5cd..6b030e35 100644
--- a/src/wscript
+++ b/src/wscript
@@ -29,8 +29,9 @@ def build(bld):
                  font.cc
                  gamma_lut.cc
                  image.cc
+                 interop_load_font.cc
+                 interop_subtitle_content.cc
                  key.cc
-                 load_font.cc
                  local_time.cc
                  metadata.cc
                  mono_picture_mxf.cc
@@ -51,6 +52,8 @@ def build(bld):
                  reel_subtitle_asset.cc
                  rgb_xyz.cc
                  signer.cc
+                 smpte_load_font.cc
+                 smpte_subtitle_content.cc
                  sound_mxf.cc
                  sound_mxf_writer.cc
                  sound_frame.cc