Initial work on SMPTE subtitles.

11 files changed, 326 insertions, 162 deletions

diff --git a/src/dcp_time.cc b/src/dcp_time.cc
index d34804e9..5d9bed81 100644
--- a/src/dcp_time.cc
+++ b/src/dcp_time.cc
@@ -66,6 +66,7 @@ Time::set (double seconds, int tcr_)
 	}
 }
 
+/** @param time String of the form HH:MM:SS:EE */
 Time::Time (string time, int tcr_)
 	: tcr (tcr_)
 {
diff --git a/src/interop_subtitle_asset.cc b/src/interop_subtitle_asset.cc
index a6bdfcaf..528b7d90 100644
--- a/src/interop_subtitle_asset.cc
+++ b/src/interop_subtitle_asset.cc
@@ -22,9 +22,11 @@
 #include "xml.h"
 #include "raw_convert.h"
 #include "font_node.h"
+#include "util.h"
 #include <libxml++/libxml++.h>
 #include <boost/foreach.hpp>
 #include <cmath>
+#include <cstdio>
 
 using std::list;
 using std::string;
@@ -40,7 +42,8 @@ InteropSubtitleAsset::InteropSubtitleAsset (boost::filesystem::path file)
 	shared_ptr<cxml::Document> xml (new cxml::Document ("DCSubtitle"));
 	xml->read_file (file);
 	_id = xml->string_child ("SubtitleID");
-
+	_reel_number = xml->string_child ("ReelNumber");
+	_language = xml->string_child ("Language");
 	_movie_title = xml->string_child ("MovieTitle");
 	_load_font_nodes = type_children<dcp::InteropLoadFontNode> (xml, "LoadFont");
 
@@ -59,15 +62,6 @@ InteropSubtitleAsset::InteropSubtitleAsset (string movie_title, string language)
 	_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
 InteropSubtitleAsset::xml_as_string () const
 {
@@ -86,102 +80,7 @@ InteropSubtitleAsset::xml_as_string () const
 		load_font->set_attribute ("URI", (*i)->uri);
 	}
 
-	list<SubtitleString> sorted = _subtitles;
-	sorted.sort (SubtitleSorter ());
-
-	/* XXX: script, underlined, weight not supported */
-
-	optional<string> font;
-	bool italic = false;
-	Colour colour;
-	int size = 0;
-	float aspect_adjust = 1.0;
-	Effect effect = NONE;
-	Colour effect_colour;
-	int spot_number = 1;
-	Time last_in;
-	Time last_out;
-	Time last_fade_up_time;
-	Time last_fade_down_time;
-
-	xmlpp::Element* font_element = 0;
-	xmlpp::Element* subtitle_element = 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 =
-			font          != i->font()          ||
-			italic        != i->italic()        ||
-			colour        != i->colour()        ||
-			size          != i->size()          ||
-			fabs (aspect_adjust - i->aspect_adjust()) > ASPECT_ADJUST_EPSILON ||
-			effect        != i->effect()        ||
-			effect_colour != i->effect_colour();
-
-		if (font_changed) {
-			font = i->font ();
-			italic = i->italic ();
-			colour = i->colour ();
-			size = i->size ();
-			aspect_adjust = i->aspect_adjust ();
-			effect = i->effect ();
-			effect_colour = i->effect_colour ();
-		}
-
-		if (!font_element || font_changed) {
-			font_element = root->add_child ("Font");
-			if (font) {
-				font_element->set_attribute ("Id", font.get ());
-			}
-			font_element->set_attribute ("Italic", italic ? "yes" : "no");
-			font_element->set_attribute ("Color", colour.to_argb_string());
-			font_element->set_attribute ("Size", raw_convert<string> (size));
-			if (fabs (aspect_adjust - 1.0) > ASPECT_ADJUST_EPSILON) {
-				font_element->set_attribute ("AspectAdjust", raw_convert<string> (aspect_adjust));
-			}
-			font_element->set_attribute ("Effect", effect_to_string (effect));
-			font_element->set_attribute ("EffectColor", effect_colour.to_argb_string());
-			font_element->set_attribute ("Script", "normal");
-			font_element->set_attribute ("Underlined", "no");
-			font_element->set_attribute ("Weight", "normal");
-		}
-
-		if (!subtitle_element || 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_element = font_element->add_child ("Subtitle");
-			subtitle_element->set_attribute ("SpotNumber", raw_convert<string> (spot_number++));
-			subtitle_element->set_attribute ("TimeIn", i->in().as_string());
-			subtitle_element->set_attribute ("TimeOut", i->out().as_string());
-			subtitle_element->set_attribute ("FadeUpTime", raw_convert<string> (i->fade_up_time().as_editable_units(250)));
-			subtitle_element->set_attribute ("FadeDownTime", raw_convert<string> (i->fade_down_time().as_editable_units(250)));
-
-			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_element->add_child ("Text");
-		if (i->h_align() != HALIGN_CENTER) {
-			text->set_attribute ("HAlign", halign_to_string (i->h_align ()));
-		}
-		if (i->h_position() > ALIGN_EPSILON) {
-			text->set_attribute ("HPosition", raw_convert<string> (i->h_position() * 100, 6));
-		}
-		text->set_attribute ("VAlign", valign_to_string (i->v_align()));		
-		text->set_attribute ("VPosition", raw_convert<string> (i->v_position() * 100, 6));
-		text->add_child_text (i->text());
-	}
+	subtitles_as_xml (root, 250, "");
 
 	return doc.write_to_string_formatted ("UTF-8");
 }
@@ -237,3 +136,19 @@ InteropSubtitleAsset::load_font_nodes () const
 	copy (_load_font_nodes.begin(), _load_font_nodes.end(), back_inserter (lf));
 	return lf;
 }
+
+/** Write this content to an XML file */
+void
+InteropSubtitleAsset::write (boost::filesystem::path p) const
+{
+	FILE* f = fopen_boost (p, "w");
+	if (!f) {
+		throw FileError ("Could not open file for writing", p, -1);
+	}
+	
+	Glib::ustring const s = xml_as_string ();
+	fwrite (s.c_str(), 1, s.bytes(), f);
+	fclose (f);
+
+	_file = p;
+}
diff --git a/src/interop_subtitle_asset.h b/src/interop_subtitle_asset.h
index 586bb67c..2a1fae7f 100644
--- a/src/interop_subtitle_asset.h
+++ b/src/interop_subtitle_asset.h
@@ -41,8 +41,41 @@ public:
 	void add_font (std::string id, std::string uri);
 	
 	Glib::ustring xml_as_string () const;
+	void write (boost::filesystem::path path) const;
+
+	void set_reel_number (std::string n) {
+		_reel_number = n;
+	}
+
+	void set_language (std::string l) {
+		_language = l;
+	}
+
+	void set_movie_title (std::string m) {
+		_movie_title = m;
+	}
+
+	std::string reel_number () const {
+		return _reel_number;
+	}
+	
+	std::string language () const {
+		return _language;
+	}
+
+	std::string movie_title () const {
+		return _movie_title;
+	}
+
+protected:
+	
+	std::string pkl_type (Standard) const {
+		return "text/xml";
+	}
 
 private:
+	std::string _reel_number;
+	std::string _language;
 	std::string _movie_title;
 	std::list<boost::shared_ptr<InteropLoadFontNode> > _load_font_nodes;
 };
diff --git a/src/mxf.cc b/src/mxf.cc
index 80a351e6..0cde395c 100644
--- a/src/mxf.cc
+++ b/src/mxf.cc
@@ -54,7 +54,7 @@ MXF::~MXF ()
 }
 
 void
-MXF::fill_writer_info (ASDCP::WriterInfo* writer_info, string id, Standard standard)
+MXF::fill_writer_info (ASDCP::WriterInfo* writer_info, string id, Standard standard) const
 {
 	writer_info->ProductVersion = _metadata.product_version;
 	writer_info->CompanyName = _metadata.company_name;
diff --git a/src/mxf.h b/src/mxf.h
index a9f1bfa3..60c635be 100644
--- a/src/mxf.h
+++ b/src/mxf.h
@@ -95,7 +95,7 @@ protected:
 	 *  @param w struct to fill in.
 	 *  @param standard INTEROP or SMPTE.
 	 */
-	void fill_writer_info (ASDCP::WriterInfo* w, std::string id, Standard standard);
+	void fill_writer_info (ASDCP::WriterInfo* w, std::string id, Standard standard) const;
 
 	ASDCP::AESDecContext* _decryption_context;
 	/** ID of the key used for encryption/decryption, if there is one */
diff --git a/src/smpte_subtitle_asset.cc b/src/smpte_subtitle_asset.cc
index e5a083b1..40afc76d 100644
--- a/src/smpte_subtitle_asset.cc
+++ b/src/smpte_subtitle_asset.cc
@@ -24,13 +24,19 @@
 #include "xml.h"
 #include "AS_DCP.h"
 #include "KM_util.h"
+#include "raw_convert.h"
+#include <libxml++/libxml++.h>
 #include <boost/foreach.hpp>
+#include <boost/algorithm/string.hpp>
 
 using std::string;
 using std::list;
 using std::stringstream;
 using std::cout;
+using std::vector;
 using boost::shared_ptr;
+using boost::split;
+using boost::is_any_of;
 using namespace dcp;
 
 SMPTESubtitleAsset::SMPTESubtitleAsset (boost::filesystem::path file, bool mxf)
@@ -64,16 +70,37 @@ SMPTESubtitleAsset::SMPTESubtitleAsset (boost::filesystem::path file, bool mxf)
 	
 	_load_font_nodes = type_children<dcp::SMPTELoadFontNode> (xml, "LoadFont");
 
-	int tcr = xml->number_child<int> ("TimeCodeRate");
+	_content_title_text = xml->string_child ("ContentTitleText");
+	_annotation_text = xml->optional_string_child ("AnnotationText");
+	_issue_date = LocalTime (xml->string_child ("IssueDate"));
+	_reel_number = xml->optional_number_child<int> ("ReelNumber");
+	_language = xml->optional_string_child ("Language");
+
+	/* This is supposed to be two numbers, but a single number has been seen in the wild */
+	string const er = xml->string_child ("EditRate");
+	vector<string> er_parts;
+	split (er_parts, er, is_any_of (" "));
+	if (er_parts.size() == 1) {
+		_edit_rate = Fraction (raw_convert<int> (er_parts[0]), 1);
+	} else if (er_parts.size() == 2) {
+		_edit_rate = Fraction (raw_convert<int> (er_parts[0]), raw_convert<int> (er_parts[1]));
+	} else {
+		throw XMLError ("malformed EditRate " + er);
+	}
+
+	_time_code_rate = xml->number_child<int> ("TimeCodeRate");
+	if (xml->optional_string_child ("StartTime")) {
+		_start_time = Time (xml->string_child ("StartTime"), _time_code_rate);
+	}
 
 	shared_ptr<cxml::Node> subtitle_list = xml->optional_node_child ("SubtitleList");
 
 	list<cxml::NodePtr> f = subtitle_list->node_children ("Font");
 	list<shared_ptr<dcp::FontNode> > font_nodes;
 	BOOST_FOREACH (cxml::NodePtr& i, f) {
-		font_nodes.push_back (shared_ptr<FontNode> (new FontNode (i, tcr)));
+		font_nodes.push_back (shared_ptr<FontNode> (new FontNode (i, _time_code_rate)));
 	}
-
+	
 	parse_common (xml, font_nodes);
 }
 
@@ -92,3 +119,79 @@ SMPTESubtitleAsset::valid_mxf (boost::filesystem::path file)
 	Kumu::Result_t r = reader.OpenRead (file.string().c_str ());
 	return !ASDCP_FAILURE (r);
 }
+
+Glib::ustring
+SMPTESubtitleAsset::xml_as_string () const
+{
+	xmlpp::Document doc;
+	xmlpp::Element* root = doc.create_root_node ("dcst:SubtitleReel");
+	root->set_namespace_declaration ("http://www.smpte-ra.org/schemas/428-7/2010/DCST", "dcst");
+	root->set_namespace_declaration ("http://www.w3.org/2001/XMLSchema", "xs");
+
+	root->add_child("ID", "dcst")->add_child_text (_id);
+	root->add_child("ContentTitleText", "dcst")->add_child_text (_content_title_text);
+	if (_annotation_text) {
+		root->add_child("AnnotationText", "dcst")->add_child_text (_annotation_text.get ());
+	}
+	root->add_child("IssueDate", "dcst")->add_child_text (_issue_date.as_string (true));
+	if (_reel_number) {
+		root->add_child("ReelNumber", "dcst")->add_child_text (raw_convert<string> (_reel_number.get ()));
+	}
+	if (_language) {
+		root->add_child("Language", "dcst")->add_child_text (_language.get ());
+	}
+	root->add_child("EditRate", "dcst")->add_child_text (_edit_rate.as_string ());
+	root->add_child("TimeCodeRate", "dcst")->add_child_text (raw_convert<string> (_time_code_rate));
+	if (_start_time) {
+		root->add_child("StartTime", "dcst")->add_child_text (_start_time.get().as_string ());
+	}
+
+	BOOST_FOREACH (shared_ptr<SMPTELoadFontNode> i, _load_font_nodes) {
+		xmlpp::Element* load_font = root->add_child("LoadFont", "dcst");
+		load_font->add_child_text (i->urn);
+		load_font->set_attribute ("ID", i->id);
+	}
+	
+	subtitles_as_xml (root->add_child ("SubtitleList", "dcst"), _time_code_rate, "dcst");
+	
+	return doc.write_to_string_formatted ("UTF-8");
+}
+
+/** Write this content to a MXF file */
+void
+SMPTESubtitleAsset::write (boost::filesystem::path p) const
+{
+	ASDCP::WriterInfo writer_info;
+	fill_writer_info (&writer_info, _id, SMPTE);
+	
+	ASDCP::TimedText::TimedTextDescriptor descriptor;
+	descriptor.EditRate = ASDCP::Rational (_edit_rate.numerator, _edit_rate.denominator);
+	descriptor.EncodingName = "UTF-8";
+	descriptor.ResourceList.clear ();
+	descriptor.NamespaceName = "dcst";
+	memcpy (descriptor.AssetID, writer_info.AssetUUID, ASDCP::UUIDlen);
+	descriptor.ContainerDuration = latest_subtitle_out().as_editable_units (_edit_rate.numerator / _edit_rate.denominator);
+
+	/* XXX: fonts into descriptor? */
+	
+	ASDCP::TimedText::MXFWriter writer;
+	Kumu::Result_t r = writer.OpenWrite (p.string().c_str(), writer_info, descriptor);
+	if (ASDCP_FAILURE (r)) {
+		boost::throw_exception (FileError ("could not open subtitle MXF for writing", p.string(), r));
+	}
+
+	/* XXX: no encryption */
+	writer.WriteTimedTextResource (xml_as_string ());
+
+	writer.Finalize ();
+
+	_file = p;
+}
+
+bool
+SMPTESubtitleAsset::equals (shared_ptr<const Asset> other_asset, EqualityOptions options, NoteHandler note) const
+{
+	/* XXX */
+	return false;
+}
+
diff --git a/src/smpte_subtitle_asset.h b/src/smpte_subtitle_asset.h
index 639c8eb7..5f4d8833 100644
--- a/src/smpte_subtitle_asset.h
+++ b/src/smpte_subtitle_asset.h
@@ -18,13 +18,15 @@
 */
 
 #include "subtitle_asset.h"
+#include "local_time.h"
+#include "mxf.h"
 #include <boost/filesystem.hpp>
 
 namespace dcp {
 
 class SMPTELoadFontNode;
 
-class SMPTESubtitleAsset : public SubtitleAsset
+class SMPTESubtitleAsset : public SubtitleAsset, public MXF
 {
 public:
 	/** @param file File name
@@ -32,11 +34,40 @@ public:
 	 */
 	SMPTESubtitleAsset (boost::filesystem::path file, bool mxf = true);
 
+	bool equals (
+		boost::shared_ptr<const Asset>,
+		EqualityOptions,
+		NoteHandler note
+		) const;
+	
 	std::list<boost::shared_ptr<LoadFontNode> > load_font_nodes () const;
 
+	Glib::ustring xml_as_string () const;
+	void write (boost::filesystem::path path) const;
+
+	/** @return language, if one was specified */
+	boost::optional<std::string> language () const {
+		return _language;
+	}
+	
 	static bool valid_mxf (boost::filesystem::path);
+
+protected:
+	
+	std::string pkl_type (Standard) const {
+		return "application/mxf";
+	}
 	
 private:
+	std::string _content_title_text;
+	boost::optional<std::string> _annotation_text;
+	LocalTime _issue_date;
+	boost::optional<int> _reel_number;
+	boost::optional<std::string> _language;
+	Fraction _edit_rate;
+	int _time_code_rate;
+	boost::optional<Time> _start_time;
+	
 	std::list<boost::shared_ptr<SMPTELoadFontNode> > _load_font_nodes;
 };
 
diff --git a/src/subtitle_asset.cc b/src/subtitle_asset.cc
index f1ecc939..1c341de4 100644
--- a/src/subtitle_asset.cc
+++ b/src/subtitle_asset.cc
@@ -43,14 +43,12 @@ using boost::dynamic_pointer_cast;
 using namespace dcp;
 
 SubtitleAsset::SubtitleAsset ()
-	: _reel_number ("1")
 {
 
 }
 
 SubtitleAsset::SubtitleAsset (boost::filesystem::path file)
 	: Asset (file)
-	, _reel_number ("1")
 {
 
 }
@@ -58,13 +56,7 @@ SubtitleAsset::SubtitleAsset (boost::filesystem::path file)
 void
 SubtitleAsset::parse_common (shared_ptr<cxml::Document> xml, list<shared_ptr<dcp::FontNode> > font_nodes)
 {
-	_reel_number = xml->string_child ("ReelNumber");
-	_language = xml->string_child ("Language");
-
-	/* Now make Subtitle objects to represent the raw XML nodes
-	   in a sane way.
-	*/
-
+	/* Make Subtitle objects to represent the raw XML nodes in a sane way */
 	ParseState parse_state;
 	examine_font_nodes (xml, font_nodes, parse_state);
 }
@@ -169,21 +161,6 @@ SubtitleAsset::add (SubtitleString s)
 	_subtitles.push_back (s);
 }
 
-void
-SubtitleAsset::write_xml (boost::filesystem::path p) const
-{
-	FILE* f = fopen_boost (p, "w");
-	if (!f) {
-		throw FileError ("Could not open file for writing", p, -1);
-	}
-	
-	Glib::ustring const s = xml_as_string ();
-	fwrite (s.c_str(), 1, s.bytes(), f);
-	fclose (f);
-
-	_file = p;
-}
-
 Time
 SubtitleAsset::latest_subtitle_out () const
 {
@@ -209,16 +186,6 @@ SubtitleAsset::equals (shared_ptr<const Asset> other_asset, EqualityOptions opti
 		return false;
 	}
 
-	if (_reel_number != other->_reel_number) {
-		note (DCP_ERROR, "subtitle reel numbers differ");
-		return false;
-	}
-
-	if (_language != other->_language) {
-		note (DCP_ERROR, "subtitle languages differ");
-		return false;
-	}
-
 	if (_subtitles != other->_subtitles) {
 		note (DCP_ERROR, "subtitles differ");
 		return false;
@@ -226,3 +193,115 @@ SubtitleAsset::equals (shared_ptr<const Asset> other_asset, EqualityOptions opti
 
 	return true;
 }
+
+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
+SubtitleAsset::subtitles_as_xml (xmlpp::Element* root, int time_code_rate, string xmlns) const
+{
+	list<SubtitleString> sorted = _subtitles;
+	sorted.sort (SubtitleSorter ());
+
+	/* XXX: script, underlined, weight not supported */
+
+	optional<string> font;
+	bool italic = false;
+	Colour colour;
+	int size = 0;
+	float aspect_adjust = 1.0;
+	Effect effect = NONE;
+	Colour effect_colour;
+	int spot_number = 1;
+	Time last_in;
+	Time last_out;
+	Time last_fade_up_time;
+	Time last_fade_down_time;
+
+	xmlpp::Element* font_element = 0;
+	xmlpp::Element* subtitle_element = 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 =
+			font          != i->font()          ||
+			italic        != i->italic()        ||
+			colour        != i->colour()        ||
+			size          != i->size()          ||
+			fabs (aspect_adjust - i->aspect_adjust()) > ASPECT_ADJUST_EPSILON ||
+			effect        != i->effect()        ||
+			effect_colour != i->effect_colour();
+
+		if (font_changed) {
+			font = i->font ();
+			italic = i->italic ();
+			colour = i->colour ();
+			size = i->size ();
+			aspect_adjust = i->aspect_adjust ();
+			effect = i->effect ();
+			effect_colour = i->effect_colour ();
+		}
+
+		if (!font_element || font_changed) {
+			font_element = root->add_child ("Font", xmlns);
+			if (font) {
+				font_element->set_attribute ("Id", font.get ());
+			}
+			font_element->set_attribute ("Italic", italic ? "yes" : "no");
+			font_element->set_attribute ("Color", colour.to_argb_string());
+			font_element->set_attribute ("Size", raw_convert<string> (size));
+			if (fabs (aspect_adjust - 1.0) > ASPECT_ADJUST_EPSILON) {
+				font_element->set_attribute ("AspectAdjust", raw_convert<string> (aspect_adjust));
+			}
+			font_element->set_attribute ("Effect", effect_to_string (effect));
+			font_element->set_attribute ("EffectColor", effect_colour.to_argb_string());
+			font_element->set_attribute ("Script", "normal");
+			font_element->set_attribute ("Underlined", "no");
+			font_element->set_attribute ("Weight", "normal");
+		}
+
+		if (!subtitle_element || 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_element = font_element->add_child ("Subtitle", xmlns);
+			subtitle_element->set_attribute ("SpotNumber", raw_convert<string> (spot_number++));
+			subtitle_element->set_attribute ("TimeIn", i->in().rebase(time_code_rate).as_string());
+			subtitle_element->set_attribute ("TimeOut", i->out().rebase(time_code_rate).as_string());
+			subtitle_element->set_attribute ("FadeUpTime", raw_convert<string> (i->fade_up_time().as_editable_units(time_code_rate)));
+			subtitle_element->set_attribute ("FadeDownTime", raw_convert<string> (i->fade_down_time().as_editable_units(time_code_rate)));
+
+			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_element->add_child ("Text", xmlns);
+		if (i->h_align() != HALIGN_CENTER) {
+			text->set_attribute ("HAlign", halign_to_string (i->h_align ()));
+		}
+		if (i->h_position() > ALIGN_EPSILON) {
+			text->set_attribute ("HPosition", raw_convert<string> (i->h_position() * 100, 6));
+		}
+		text->set_attribute ("VAlign", valign_to_string (i->v_align()));		
+		text->set_attribute ("VPosition", raw_convert<string> (i->v_position() * 100, 6));
+		text->add_child_text (i->text());
+	}
+}
+
+       
diff --git a/src/subtitle_asset.h b/src/subtitle_asset.h
index deb72ece..c8100d58 100644
--- a/src/subtitle_asset.h
+++ b/src/subtitle_asset.h
@@ -25,6 +25,10 @@
 #include "subtitle_string.h"
 #include <libcxml/cxml.h>
 
+namespace xmlpp {
+	class Element;
+}
+
 namespace dcp
 {
 
@@ -49,10 +53,6 @@ public:
 		NoteHandler note
 		) const;
 
-	std::string language () const {
-		return _language;
-	}
-
 	std::list<SubtitleString> subtitles_during (Time from, Time to) const;
 	std::list<SubtitleString> const & subtitles () const {
 		return _subtitles;
@@ -60,11 +60,8 @@ public:
 
 	void add (SubtitleString);
 
-	void write_xml (boost::filesystem::path) const;
-	virtual Glib::ustring xml_as_string () const {
-		/* XXX: this should be pure virtual when SMPTE writing is implemented */
-		return "";
-	}
+	virtual void write (boost::filesystem::path) const = 0;
+	virtual Glib::ustring xml_as_string () const = 0;
 
 	Time latest_subtitle_out () const;
 
@@ -73,18 +70,14 @@ public:
 protected:
 	void parse_common (boost::shared_ptr<cxml::Document> xml, std::list<boost::shared_ptr<FontNode> > font_nodes);
 	
-	std::string pkl_type (Standard) const {
-		return "text/xml";
-	}
+	virtual std::string pkl_type (Standard) const = 0;
 
 	std::string asdcp_kind () const {
 		return "Subtitle";
 	}
-	
-	/* strangely, this is sometimes a string */
-	std::string _reel_number;
-	std::string _language;
 
+	void subtitles_as_xml (xmlpp::Element* root, int time_code_rate, std::string xmlns) const;
+	
 	std::list<SubtitleString> _subtitles;
 
 private:
diff --git a/src/types.cc b/src/types.cc
index e86e999c..37666701 100644
--- a/src/types.cc
+++ b/src/types.cc
@@ -20,6 +20,7 @@
 #include "raw_convert.h"
 #include "types.h"
 #include "exceptions.h"
+#include "compose.hpp"
 #include <boost/algorithm/string.hpp>
 #include <vector>
 #include <cstdio>
@@ -43,6 +44,12 @@ Fraction::Fraction (string s)
 	denominator = raw_convert<int> (b[1]);
 }
 
+string
+Fraction::as_string () const
+{
+	return String::compose ("%1 %2", numerator, denominator);
+}
+
 bool
 dcp::operator== (Fraction const & a, Fraction const & b)
 {
diff --git a/src/types.h b/src/types.h
index 626666b4..ca7603ab 100644
--- a/src/types.h
+++ b/src/types.h
@@ -139,6 +139,8 @@ public:
 		return float (numerator) / denominator;
 	}
 
+	std::string as_string () const;
+
 	int numerator;
 	int denominator;
 };