Re-work time.

41 files changed, 661 insertions, 929 deletions

diff --git a/src/dcp/subtitle.cc b/src/dcp/subtitle.cc
index ba3c278..d8bae8d 100644
--- a/src/dcp/subtitle.cc
+++ b/src/dcp/subtitle.cc
@@ -33,37 +33,37 @@ using boost::lexical_cast;
 using boost::is_any_of;
 using namespace sub;
 
-dcp::Subtitle::Subtitle (boost::shared_ptr<const cxml::Node> node, bool smpte)
+dcp::Subtitle::Subtitle (boost::shared_ptr<const cxml::Node> node, optional<int> tcr)
 {
-	if (smpte) {
-		in = smpte_time (node, "TimeIn").get ();
-		out = smpte_time (node, "TimeOut").get ();
+	if (tcr) {
+		in = smpte_time (node, "TimeIn", tcr.get ()).get ();
+		out = smpte_time (node, "TimeOut", tcr.get ()).get ();
 	} else {
 		in = interop_time (node, "TimeIn").get ();
 		out = interop_time (node, "TimeOut").get ();
 	}
 
-	if (smpte) {
-		fade_up_time = smpte_time (node, "FadeUpTime").get_value_or (FrameTime (0, 0, 0, 2));
-		fade_down_time = smpte_time (node, "FadeDownTime").get_value_or (FrameTime (0, 0, 0, 2));
+	if (tcr) {
+		fade_up_time = smpte_time (node, "FadeUpTime", tcr.get ()).get_value_or (Time::from_hmsf (0, 0, 0, 2, value_to_enum (tcr.get ())));
+		fade_down_time = smpte_time (node, "FadeDownTime", tcr.get ()).get_value_or (Time::from_hmsf (0, 0, 0, 2, value_to_enum (tcr.get ())));
 	} else {
-		fade_up_time = interop_time (node, "FadeUpTime").get_value_or (MetricTime (0, 0, 0, 80));
-		if (fade_up_time.metric() > MetricTime (0, 0, 8, 0)) {
-			fade_up_time = MetricTime (0, 0, 8, 0);
+		fade_up_time = interop_time (node, "FadeUpTime").get_value_or (Time::from_hmsm (0, 0, 0, 80));
+		if (fade_up_time > Time::from_hmsm (0, 0, 8, 0)) {
+			fade_up_time = Time::from_hmsm (0, 0, 8, 0);
 		}
-		fade_down_time = interop_time (node, "FadeDownTime").get_value_or (MetricTime (0, 0, 0, 80));
-		if (fade_down_time.metric() > MetricTime (0, 0, 8, 0)) {
-			fade_down_time = MetricTime (0, 0, 8, 0);
+		fade_down_time = interop_time (node, "FadeDownTime").get_value_or (Time::from_hmsm (0, 0, 0, 80));
+		if (fade_down_time > Time::from_hmsm (0, 0, 8, 0)) {
+			fade_down_time = Time::from_hmsm (0, 0, 8, 0);
 		}
 	}
 }
 
-optional<FrameTime>
-dcp::Subtitle::smpte_time (shared_ptr<const cxml::Node> node, string name)
+optional<Time>
+dcp::Subtitle::smpte_time (shared_ptr<const cxml::Node> node, string name, int tcr)
 {
 	optional<string> u = node->optional_string_attribute (name);
 	if (!u) {
-		return optional<FrameTime> ();
+		return optional<Time> ();
 	}
 	
 	vector<string> b;
@@ -72,24 +72,23 @@ dcp::Subtitle::smpte_time (shared_ptr<const cxml::Node> node, string name)
 		boost::throw_exception (DCPError ("unrecognised time specification " + u.get ()));
 	}
 	
-	return FrameTime (
+	return Time::from_hmsf (
 		raw_convert<int> (b[0]),
 		raw_convert<int> (b[1]),
 		raw_convert<int> (b[2]),
-		raw_convert<int> (b[3])
+		raw_convert<int> (b[3]),
+		value_to_enum (tcr)
 		);
 }
 
-optional<MetricTime>
+optional<Time>
 dcp::Subtitle::interop_time (shared_ptr<const cxml::Node> node, string name)
 {
 	optional<string> u = node->optional_string_attribute (name);
 	if (!u) {
-		return optional<MetricTime> ();
+		return optional<Time> ();
 	}
 
-	MetricTime t;
-
 	if (u.get().find (":") != string::npos) {
 		/* HH:MM:SS:TTT or HH:MM:SS.sss */
 		vector<string> b;
@@ -99,14 +98,13 @@ dcp::Subtitle::interop_time (shared_ptr<const cxml::Node> node, string name)
 		}
 
 		if (u.get().find (".") != string::npos) {
-			return MetricTime (
+			return Time::from_hms (
 				raw_convert<int> (b[0]),
 				raw_convert<int> (b[1]),
-				raw_convert<int> (b[2]),
-				raw_convert<int> ("." + b[3])
+				raw_convert<double> (b[2] + "." + b[3])
 				);
 		} else {
-			return MetricTime (
+			return Time::from_hmsm (
 				raw_convert<int> (b[0]),
 				raw_convert<int> (b[1]),
 				raw_convert<int> (b[2]),
@@ -114,8 +112,6 @@ dcp::Subtitle::interop_time (shared_ptr<const cxml::Node> node, string name)
 				);
 		}
 	} else {
-		return MetricTime (0, 0, 0, raw_convert<int> (u.get ()) * 4);
+		return Time::from_hmsm (0, 0, 0, raw_convert<int> (u.get ()) * 4);
 	}
-
-	assert (false);
 }
diff --git a/src/dcp/subtitle.h b/src/dcp/subtitle.h
index 95c96cf..672dc9a 100644
--- a/src/dcp/subtitle.h
+++ b/src/dcp/subtitle.h
@@ -20,7 +20,7 @@
 #ifndef LIBSUB_DCP_SUBTITLE_H
 #define LIBSUB_DCP_SUBTITLE_H
 
-#include "../time_pair.h"
+#include "../sub_time.h"
 #include <boost/shared_ptr.hpp>
 #include <boost/optional.hpp>
 #include <list>
@@ -39,16 +39,16 @@ class Subtitle
 {
 public:
 	Subtitle () {}
-	Subtitle (boost::shared_ptr<const cxml::Node> node, bool smpte);
+	Subtitle (boost::shared_ptr<const cxml::Node> node, boost::optional<int> tcr);
 
-	TimePair in;
-	TimePair out;
-	TimePair fade_up_time;
-	TimePair fade_down_time;
+	Time in;
+	Time out;
+	Time fade_up_time;
+	Time fade_down_time;
 
 private:
-	boost::optional<FrameTime> smpte_time (boost::shared_ptr<const cxml::Node> node, std::string name);
-	boost::optional<MetricTime> interop_time (boost::shared_ptr<const cxml::Node> node, std::string name);
+	boost::optional<Time> smpte_time (boost::shared_ptr<const cxml::Node> node, std::string name, int tcr);
+	boost::optional<Time> interop_time (boost::shared_ptr<const cxml::Node> node, std::string name);
 };
 
 }
diff --git a/src/dcp_reader.cc b/src/dcp_reader.cc
index dbe318c..e83f79c 100644
--- a/src/dcp_reader.cc
+++ b/src/dcp_reader.cc
@@ -31,20 +31,21 @@ using std::list;
 using std::cout;
 using std::string;
 using boost::shared_ptr;
+using boost::optional;
 using namespace sub;
 
 void
-DCPReader::parse_common (cxml::NodePtr root, bool smpte)
+DCPReader::parse_common (cxml::NodePtr root, optional<int> tcr)
 {
 	_reel_number = root->string_child ("ReelNumber");
 	_language = root->string_child ("Language");
 
 	ParseState parse_state;
-	parse_node (root->node(), parse_state, smpte);
+	parse_node (root->node(), parse_state, tcr);
 }
 
 void
-DCPReader::parse_node (xmlpp::Node const * node, ParseState& parse_state, bool smpte)
+DCPReader::parse_node (xmlpp::Node const * node, ParseState& parse_state, optional<int> tcr)
 {
 	xmlpp::Node::NodeList children = node->get_children ();
 	for (xmlpp::Node::NodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
@@ -58,18 +59,18 @@ DCPReader::parse_node (xmlpp::Node const * node, ParseState& parse_state, bool s
 			cxml::ConstNodePtr n (new cxml::Node (e));
 			if (n->name() == "Font") {
 				parse_state.font_nodes.push_back (shared_ptr<dcp::Font> (new dcp::Font (n)));
-				parse_node (e, parse_state, smpte);
+				parse_node (e, parse_state, tcr);
 				parse_state.font_nodes.pop_back ();
 			} else if (n->name() == "Text") {
 				parse_state.text_nodes.push_back (shared_ptr<dcp::Text> (new dcp::Text (n)));
-				parse_node (e, parse_state, smpte);
+				parse_node (e, parse_state, tcr);
 				parse_state.text_nodes.pop_back ();
 			} else if (n->name() == "Subtitle") {
-				parse_state.subtitle_nodes.push_back (shared_ptr<dcp::Subtitle> (new dcp::Subtitle (n, smpte)));
-				parse_node (e, parse_state, smpte);
+				parse_state.subtitle_nodes.push_back (shared_ptr<dcp::Subtitle> (new dcp::Subtitle (n, tcr)));
+				parse_node (e, parse_state, tcr);
 				parse_state.subtitle_nodes.pop_back ();
 			} else if (n->name() == "SubtitleList") {
-				parse_node (e, parse_state, smpte);
+				parse_node (e, parse_state, tcr);
 			}
 		}
 	}
diff --git a/src/dcp_reader.h b/src/dcp_reader.h
index 07324b4..f749f82 100644
--- a/src/dcp_reader.h
+++ b/src/dcp_reader.h
@@ -46,12 +46,12 @@ protected:
 		std::list<boost::shared_ptr<dcp::Subtitle> > subtitle_nodes;
 	};
 
-	void parse_common (cxml::NodePtr root, bool smpte);
+	void parse_common (cxml::NodePtr root, boost::optional<int> tcr);
 
 	std::string _id;
 	
 private:
-	void parse_node (xmlpp::Node const * node, ParseState& parse_state, bool smtpe);
+	void parse_node (xmlpp::Node const * node, ParseState& parse_state, boost::optional<int> tcr);
 	void maybe_add_subtitle (std::string text, ParseState const & parse_state);
 	
 	std::string _reel_number;
diff --git a/src/exceptions.h b/src/exceptions.h
index 4ec931e..8602517 100644
--- a/src/exceptions.h
+++ b/src/exceptions.h
@@ -91,6 +91,22 @@ public:
 	{}
 };
 
+class UnknownFrameRateException : public MessageError
+{
+public:
+	UnknownFrameRateException ()
+		: MessageError ("subtitle frame rate required but not known")
+	{}
+};
+
+class UnsupportedFrameRateException : public MessageError
+{
+public:
+	UnsupportedFrameRateException ()
+		: MessageError ("frame rate not supported")
+	{}
+};
+
 }
 
 #endif
diff --git a/src/frame_rate.cc b/src/frame_rate.cc
new file mode 100644
index 0000000..efc87d1
--- /dev/null
+++ b/src/frame_rate.cc
@@ -0,0 +1,59 @@
+/*
+    Copyright (C) 2015 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 "frame_rate.h"
+#include "exceptions.h"
+#include <cmath>
+
+double
+sub::enum_to_value (FrameRate r)
+{
+	switch (r) {
+	case TWENTY_THREE_DROP:
+		return 23.976;
+	case TWENTY_FOUR:
+		return 24;
+	case TWENTY_FIVE:
+		return 25;
+	case THIRTY_DROP:
+		return 29.97;
+	case THIRTY:
+		return 30;
+	}
+
+	return TWENTY_FOUR;
+}
+
+sub::FrameRate
+sub::value_to_enum (double r)
+{
+	if (fabs (r - 23.976) < 0.001) {
+		return TWENTY_THREE_DROP;
+	} else if (fabs (r - 24) < 0.001) {
+		return TWENTY_FOUR;
+	} else if (fabs (r - 25) < 0.001) {
+		return TWENTY_FIVE;
+	} else if (fabs (r - 29.97) < 0.001) {
+		return THIRTY_DROP;
+	} else if (fabs (r - 30) < 0.001) {
+		return THIRTY;
+	}
+
+	throw UnsupportedFrameRateException ();
+}
diff --git a/src/frame_rate.h b/src/frame_rate.h
new file mode 100644
index 0000000..dd973ed
--- /dev/null
+++ b/src/frame_rate.h
@@ -0,0 +1,38 @@
+/*
+    Copyright (C) 2015 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.
+
+*/
+
+#ifndef LIBSUB_FRAME_RATE_H
+#define LIBSUB_FRAME_RATE_H
+
+namespace sub {
+	
+enum FrameRate {
+	TWENTY_THREE_DROP,
+	TWENTY_FOUR,
+	TWENTY_FIVE,
+	THIRTY_DROP,
+	THIRTY
+};
+
+extern double enum_to_value (FrameRate);
+extern FrameRate value_to_enum (double);
+
+}
+
+#endif
diff --git a/src/frame_time.cc b/src/frame_time.cc
deleted file mode 100644
index c67bd68..0000000
--- a/src/frame_time.cc
+++ /dev/null
@@ -1,131 +0,0 @@
-/*
-    Copyright (C) 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 "frame_time.h"
-#include "compose.hpp"
-#include <iostream>
-
-using std::ostream;
-using std::string;
-using namespace sub;
-
-bool
-sub::operator== (FrameTime const & a, FrameTime const & b)
-{
-	return a.hours() == b.hours() && a.minutes() == b.minutes() && a.seconds() == b.seconds() && a.frames() == b.frames();
-}
-
-bool
-sub::operator< (FrameTime const & a, FrameTime const & b)
-{
-	if (a.hours() != b.hours()) {
-		return a.hours() < b.hours();
-	}
-
-	if (a.minutes() != b.minutes()) {
-		return a.minutes() < b.minutes();
-	}
-
-	if (a.seconds() != b.seconds()) {
-		return a.seconds() < b.seconds();
-	}
-
-	return a.frames() < b.frames();
-}
-
-bool
-sub::operator> (FrameTime const & a, FrameTime const & b)
-{
-	if (a.hours() != b.hours()) {
-		return a.hours() > b.hours();
-	}
-
-	if (a.minutes() != b.minutes()) {
-		return a.minutes() > b.minutes();
-	}
-
-	if (a.seconds() != b.seconds()) {
-		return a.seconds() > b.seconds();
-	}
-
-	return a.frames() > b.frames();
-}
-
-ostream&
-sub::operator<< (ostream& s, FrameTime const & t)
-{
-	s << t.hours() << ":" << t.minutes() << ":" << t.seconds() << ":" << t.frames();
-	return s;
-}
-
-string
-FrameTime::timecode () const
-{
-	return String::compose ("%1:%2:%3:%4", _hours, _minutes, _seconds, _frames);
-}
-
-FrameTime::FrameTime (int64_t f, float fps)
-{
-	set_from_frames (f, fps);
-}
-
-void
-FrameTime::set_from_frames (int64_t f, float fps)
-{
-	_hours = f / (60 * 60 * fps);
-	f -= _hours * 60 * 60 * fps;
-	_minutes = f / (60 * fps);
-	f -= _minutes * 60 * fps;
-	_seconds = f / fps;
-	f -= _seconds * fps;
-	_frames = int (f);
-}
-
-void
-FrameTime::add (FrameTime t, float fps)
-{
-	_frames += t.frames ();
-	if (_frames > fps) {
-		_frames -= fps;
-		_seconds++;
-	}
-
-	_seconds += t.seconds ();
-	if (_seconds >= 60) {
-		_seconds -= 60;
-		++_minutes;
-	}
-
-	_minutes += t.minutes ();
-	if (_minutes >= 60) {
-		_minutes -= 60;
-		++_hours;
-	}
-
-	_hours += t.hours ();
-}
-
-void
-FrameTime::scale (float f, float frames_per_second)
-{
-	set_from_frames (
-		(((_hours * 3600 + _minutes * 60 + _seconds) * frames_per_second) + _frames) * f,
-		frames_per_second
-		);
-}
diff --git a/src/frame_time.h b/src/frame_time.h
deleted file mode 100644
index 9125791..0000000
--- a/src/frame_time.h
+++ /dev/null
@@ -1,90 +0,0 @@
-/*
-    Copyright (C) 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.
-
-*/
-
-#ifndef LIBSUB_FRAME_TIME_H
-#define LIBSUB_FRAME_TIME_H
-
-#include <iostream>
-#include <stdint.h>
-
-namespace sub {
-
-/** @class FrameTime
- *  @brief A time stored in hours, minutes, seconds and frames.
- */
-class FrameTime
-{
-public:
-	FrameTime ()
-		: _hours (0)
-		, _minutes (0)
-		, _seconds (0)
-		, _frames (0)
-	{}
-
-	/** @param f Number of frames.
-	 *  @param fps Frames per second.
-	 */
-	FrameTime (int64_t f, float fps);
-			  
-	FrameTime (int h, int m, int s, int f)
-		: _hours (h)
-		, _minutes (m)
-		, _seconds (s)
-		, _frames (f)
-	{}
-
-	int hours () const {
-		return _hours;
-	}
-	
-	int minutes () const {
-		return _minutes;
-	}
-	
-	int seconds () const {
-		return _seconds;
-	}
-	
-	int frames () const {
-		return _frames;
-	}
-
-	std::string timecode () const;
-
-	void add (FrameTime t, float fps);
-	void scale (float f, float fps);
-
-private:
-	void set_from_frames (int64_t f, float fps);
-	
-	int _hours;
-	int _minutes;
-	int _seconds;
-	int _frames;
-};
-
-bool operator== (FrameTime const & a, FrameTime const & b);
-bool operator< (FrameTime const & a, FrameTime const & b);
-bool operator> (FrameTime const & a, FrameTime const & b);
-std::ostream& operator<< (std::ostream&, FrameTime const & t);
-	
-}
-
-#endif
diff --git a/src/interop_dcp_reader.cc b/src/interop_dcp_reader.cc
index 5767b05..5751dcd 100644
--- a/src/interop_dcp_reader.cc
+++ b/src/interop_dcp_reader.cc
@@ -26,6 +26,7 @@
 
 using std::list;
 using boost::shared_ptr;
+using boost::optional;
 using namespace sub;
 
 InteropDCPReader::InteropDCPReader (boost::filesystem::path file)
@@ -37,5 +38,5 @@ InteropDCPReader::InteropDCPReader (boost::filesystem::path file)
 	_movie_title = xml->string_child ("MovieTitle");
 	_load_font_nodes = type_children<dcp::InteropLoadFont> (xml, "LoadFont");
 
-	parse_common (xml, false);
+	parse_common (xml, optional<int> ());
 }
diff --git a/src/metric_time.cc b/src/metric_time.cc
deleted file mode 100644
index 4fad390..0000000
--- a/src/metric_time.cc
+++ /dev/null
@@ -1,120 +0,0 @@
-/*
-    Copyright (C) 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 "metric_time.h"
-#include "compose.hpp"
-#include <iostream>
-#include <cmath>
-
-using std::ostream;
-using std::string;
-using std::cout;
-using namespace sub;
-
-MetricTime::MetricTime (int h, int m, int s, int ms)
-        /* cast up to int64_t to force a 64-bit calculation */
-	: _ms ((int64_t (h) * 3600 + m * 60 + s) * 1000 + ms)
-{
-
-}
-
-void
-MetricTime::split (int& h, int &m, int& s, int& ms) const
-{
-	int64_t w = _ms;
-	h = floor (w / (3600 * 1000));
-	/* this multiply could overflow 32 bits so cast to make sure it is done as 64-bit */
-	w -= int64_t (h) * (3600 * 1000);
-	m = floor (w / (60 * 1000));
-	w -= m * (60 * 1000);
-	s = floor (w / 1000);
-	w -= s * 1000;
-	ms = w;
-}
-
-int
-MetricTime::hours () const
-{
-	int h, m, s, ms;
-	split (h, m, s, ms);
-	return h;
-}
-
-int
-MetricTime::minutes () const
-{
-	int h, m, s, ms;
-	split (h, m, s, ms);
-	return m;
-}
-
-int
-MetricTime::seconds () const
-{
-	int h, m, s, ms;
-	split (h, m, s, ms);
-	return s;
-}
-
-int
-MetricTime::milliseconds () const
-{
-	int h, m, s, ms;
-	split (h, m, s, ms);
-	return ms;
-}
-
-void
-MetricTime::add (MetricTime t)
-{
-	_ms += t._ms;
-}
-
-void
-MetricTime::scale (float f)
-{
-	_ms *= f;
-}
-
-bool
-sub::operator== (MetricTime const & a, MetricTime const & b)
-{
-	return a._ms == b._ms;
-}
-
-bool
-sub::operator> (MetricTime const & a, MetricTime const & b)
-{
-	return a._ms > b._ms;
-}
-
-bool
-sub::operator< (MetricTime const & a, MetricTime const & b)
-{
-	return a._ms < b._ms;
-}
-
-ostream&
-sub::operator<< (ostream& st, MetricTime const & t)
-{
-	int h, m, s, ms;
-	t.split (h, m, s, ms);
-	st << h << ":" << m << ":" << s << ":" << ms;
-	return st;
-}
diff --git a/src/metric_time.h b/src/metric_time.h
deleted file mode 100644
index 404464e..0000000
--- a/src/metric_time.h
+++ /dev/null
@@ -1,74 +0,0 @@
-/*
-    Copyright (C) 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.
-
-*/
-
-#ifndef LIBSUB_METRIC_TIME_H
-#define LIBSUB_METRIC_TIME_H
-
-#include <stdint.h>
-#include <iostream>
-
-namespace sub {
-
-/** @class MetricTime
- *  @brief A time stored in milliseconds.
- */
-class MetricTime
-{
-public:
-	MetricTime ()
-		: _ms (0)
-	{}
-
-	MetricTime (int h, int m, int s, int ms);
-
-	int hours () const;
-	int minutes () const;
-	int seconds () const;
-	int milliseconds () const;
-
-	double all_as_seconds () const {
-		return all_as_milliseconds() / 1000.0;
-	}
-	
-	int64_t all_as_milliseconds () const {
-		return _ms;
-	}		
-
-	void add (MetricTime t);
-	void scale (float f);
-			  
-private:
-	void split (int& h, int& m, int& s, int& ms) const;
-	
-	friend bool operator== (MetricTime const & a, MetricTime const & b);
-	friend bool operator> (MetricTime const & a, MetricTime const & b);
-	friend bool operator< (MetricTime const & a, MetricTime const & b);
-	friend std::ostream& operator<< (std::ostream&, MetricTime const & t);
-	
-	int64_t _ms;
-};
-
-bool operator== (MetricTime const & a, MetricTime const & b);
-bool operator> (MetricTime const & a, MetricTime const & b);	
-bool operator< (MetricTime const & a, MetricTime const & b);	
-std::ostream& operator<< (std::ostream&, MetricTime const & t);
-	
-}
-
-#endif
diff --git a/src/raw_subtitle.cc b/src/raw_subtitle.cc
index 24f1a8e..818bb15 100644
--- a/src/raw_subtitle.cc
+++ b/src/raw_subtitle.cc
@@ -24,13 +24,5 @@ using namespace sub;
 bool
 sub::operator< (RawSubtitle const & a, RawSubtitle const & b)
 {
-	if (a.from.frame() && b.from.frame()) {
-		return a.from.frame().get() < b.from.frame().get();
-	}
-
-	if (a.from.metric() && b.from.metric()) {
-		return a.from.metric().get() < b.from.metric().get();
-	}
-
-	assert (false);
+	return a.from < b.from;
 }
diff --git a/src/raw_subtitle.h b/src/raw_subtitle.h
index fdd7331..d812d34 100644
--- a/src/raw_subtitle.h
+++ b/src/raw_subtitle.h
@@ -20,13 +20,11 @@
 #ifndef LIBSUB_RAW_SUBTITLE_H
 #define LIBSUB_RAW_SUBTITLE_H
 
-#include "frame_time.h"
-#include "metric_time.h"
 #include "colour.h"
 #include "vertical_reference.h"
 #include "effect.h"
-#include "time_pair.h"
 #include "font_size.h"
+#include "sub_time.h"
 #include "vertical_position.h"
 #include <boost/optional.hpp>
 #include <string>
@@ -68,16 +66,16 @@ public:
 	VerticalPosition vertical_position;
 
 	/** from time */
-	TimePair from;
+	Time from;
 	/** to time */
-	TimePair to;
+	Time to;
 	
-	boost::optional<TimePair> fade_up;
-	boost::optional<TimePair> fade_down;
+	boost::optional<Time> fade_up;
+	boost::optional<Time> fade_down;
 };
 
-bool operator< (RawSubtitle const &, RawSubtitle const &);	
-
+bool operator< (RawSubtitle const &, RawSubtitle const &);
+	
 }
 
 #endif
diff --git a/src/reader_factory.cc b/src/reader_factory.cc
index 2652763..1a7a6f2 100644
--- a/src/reader_factory.cc
+++ b/src/reader_factory.cc
@@ -32,8 +32,9 @@ using boost::algorithm::ends_with;
 using boost::shared_ptr;
 using namespace sub;
 
+/** @param frame_rate Frame rate to use if the file does not specify one */
 shared_ptr<Reader>
-sub::reader_factory (boost::filesystem::path file_name)
+sub::reader_factory (boost::filesystem::path file_name, sub::FrameRate frame_rate)
 {
 	string ext = file_name.extension().string();
 	transform (ext.begin(), ext.end(), ext.begin(), ::tolower);
@@ -65,7 +66,7 @@ sub::reader_factory (boost::filesystem::path file_name)
 		if (f.gcount() == 11 && buffer[3] == 'S' && buffer[4] == 'T' && buffer[5] == 'L') {
 			return shared_ptr<Reader> (new STLBinaryReader (f));
 		} else {
-			return shared_ptr<Reader> (new STLTextReader (f));
+			return shared_ptr<Reader> (new STLTextReader (f, frame_rate));
 		}
 	}
 
diff --git a/src/reader_factory.h b/src/reader_factory.h
index e7c349b..916502c 100644
--- a/src/reader_factory.h
+++ b/src/reader_factory.h
@@ -17,6 +17,7 @@
 
 */
 
+#include "frame_rate.h"
 #include <boost/shared_ptr.hpp>
 #include <boost/filesystem.hpp>
 
@@ -25,6 +26,6 @@ namespace sub {
 class Reader;
 
 extern boost::shared_ptr<Reader>
-reader_factory (boost::filesystem::path);
+reader_factory (boost::filesystem::path, sub::FrameRate);
 
 }
diff --git a/src/smpte_dcp_reader.cc b/src/smpte_dcp_reader.cc
index b60cc8b..6014196 100644
--- a/src/smpte_dcp_reader.cc
+++ b/src/smpte_dcp_reader.cc
@@ -63,5 +63,5 @@ SMPTEDCPReader::SMPTEDCPReader (boost::filesystem::path file, bool mxf)
 	
 	_load_font_nodes = type_children<dcp::SMPTELoadFont> (xml, "LoadFont");
 
-	parse_common (xml, true);
+	parse_common (xml, xml->number_child<int> ("TimeCodeRate"));
 }
diff --git a/src/stl_binary_reader.cc b/src/stl_binary_reader.cc
index 2246a01..8a4bd1b 100644
--- a/src/stl_binary_reader.cc
+++ b/src/stl_binary_reader.cc
@@ -95,8 +95,8 @@ STLBinaryReader::STLBinaryReader (istream& in)
 
 		for (size_t i = 0; i < lines.size(); ++i) {
 			RawSubtitle sub;
-			sub.from.set_frame (get_timecode (5));
-			sub.to.set_frame (get_timecode (9));
+			sub.from = get_timecode (5);
+			sub.to = get_timecode (9);
 			sub.vertical_position.line = get_int (13, 1) + i;
 			sub.vertical_position.lines = maximum_rows;
 			sub.vertical_position.reference = TOP_OF_SCREEN;
@@ -174,10 +174,10 @@ STLBinaryReader::get_int (int offset, int length) const
 	return v;
 }
 
-FrameTime
+Time
 STLBinaryReader::get_timecode (int offset) const
 {
-	return FrameTime (_buffer[offset], _buffer[offset + 1], _buffer[offset + 2], _buffer[offset + 3]);
+	return Time::from_hmsf (_buffer[offset], _buffer[offset + 1], _buffer[offset + 2], _buffer[offset + 3]);
 }
 
 map<string, string>
diff --git a/src/stl_binary_reader.h b/src/stl_binary_reader.h
index a637e91..40bc5b7 100644
--- a/src/stl_binary_reader.h
+++ b/src/stl_binary_reader.h
@@ -21,6 +21,8 @@
 #define LIBSUB_STL_BINARY_READER_H
 
 #include "reader.h"
+#include "frame_rate.h"
+#include "sub_time.h"
 #include "stl_binary_tables.h"
 #include <map>
 
@@ -38,7 +40,7 @@ public:
 	std::map<std::string, std::string> metadata () const;
 
 	int code_page_number;
-	int frame_rate;
+	FrameRate frame_rate;
 	DisplayStandard display_standard;
 	LanguageGroup language_group;
 	Language language;
@@ -70,7 +72,7 @@ public:
 private:
 	std::string get_string (int, int) const;
 	int get_int (int, int) const;
-	FrameTime get_timecode (int) const;
+	Time get_timecode (int) const;
 
 	STLBinaryTables _tables;
 	unsigned char* _buffer;
diff --git a/src/stl_binary_writer.cc b/src/stl_binary_writer.cc
index b9ad86f..dedac84 100644
--- a/src/stl_binary_writer.cc
+++ b/src/stl_binary_writer.cc
@@ -92,7 +92,7 @@ put_int_as_int (char* p, int v, unsigned int n)
 void
 sub::write_stl_binary (
 	list<Subtitle> subtitles,
-	float frames_per_second,
+	FrameRate frame_rate,
 	Language language,
 	string original_programme_title,
 	string original_episode_title,
@@ -148,7 +148,7 @@ sub::write_stl_binary (
 	/* Code page: 850 */
 	put_string (buffer + 0, "850");
 	/* Disk format code */
-	put_string (buffer + 3, stl_frame_rate_to_dfc (frames_per_second));
+	put_string (buffer + 3, stl_frame_rate_to_dfc (frame_rate));
 	/* Display standard code: open subtitling */
 	put_string (buffer + 11, "0");
 	/* Character code table: Latin (ISO 6937) */
@@ -209,15 +209,15 @@ sub::write_stl_binary (
 			/* Cumulative status */
 			put_int_as_int (buffer + 4, tables.cumulative_status_enum_to_file (CUMULATIVE_STATUS_NOT_CUMULATIVE), 1);
 			/* Time code in */
-			put_int_as_int (buffer + 5, i->from.frame(frames_per_second).hours (), 1);
-			put_int_as_int (buffer + 6, i->from.frame(frames_per_second).minutes (), 1);
-			put_int_as_int (buffer + 7, i->from.frame(frames_per_second).seconds (), 1);
-			put_int_as_int (buffer + 8, i->from.frame(frames_per_second).frames (), 1);
+			put_int_as_int (buffer + 5, i->from.hours, 1);
+			put_int_as_int (buffer + 6, i->from.minutes, 1);
+			put_int_as_int (buffer + 7, i->from.seconds, 1);
+			put_int_as_int (buffer + 8, i->from.frames (frame_rate), 1);
 			/* Time code out */
-			put_int_as_int (buffer + 9, i->to.frame(frames_per_second).hours (), 1);
-			put_int_as_int (buffer + 10, i->to.frame(frames_per_second).minutes (), 1);
-			put_int_as_int (buffer + 11, i->to.frame(frames_per_second).seconds (), 1);
-			put_int_as_int (buffer + 12, i->to.frame(frames_per_second).frames (), 1);
+			put_int_as_int (buffer + 9, i->to.hours, 1);
+			put_int_as_int (buffer + 10, i->to.minutes, 1);
+			put_int_as_int (buffer + 11, i->to.seconds, 1);
+			put_int_as_int (buffer + 12, i->to.frames (frame_rate), 1);
 			/* Vertical position */
 			int vp = 0;
 			if (j->vertical_position.proportional) {
diff --git a/src/stl_binary_writer.h b/src/stl_binary_writer.h
index 4986afb..afddffa 100644
--- a/src/stl_binary_writer.h
+++ b/src/stl_binary_writer.h
@@ -25,6 +25,7 @@
 #define LIBSUB_STL_BINARY_WRITER_H
 
 #include "stl_binary_tables.h"
+#include "frame_rate.h"
 #include <string>
 #include <boost/filesystem.hpp>
 
@@ -34,7 +35,7 @@ class Subtitle;
 
 extern void write_stl_binary (
 	std::list<Subtitle> subtitles,
-	float frames_per_second,
+	FrameRate frames_per_second,
 	Language language,
 	std::string original_programme_title,
 	std::string original_episode_title,
diff --git a/src/stl_text_reader.cc b/src/stl_text_reader.cc
index b86a656..d5e701f 100644
--- a/src/stl_text_reader.cc
+++ b/src/stl_text_reader.cc
@@ -36,7 +36,8 @@ using boost::optional;
 using boost::lexical_cast;
 using namespace sub;
 
-STLTextReader::STLTextReader (istream& in)
+STLTextReader::STLTextReader (istream& in, sub::FrameRate frame_rate)
+	: _frame_rate (frame_rate)
 {
 	_subtitle.vertical_position.line = 0;
 	/* XXX: no idea what this should be */
@@ -88,16 +89,16 @@ STLTextReader::STLTextReader (istream& in)
 			string to_string = line.substr (divider[0] + 1, divider[1] - divider[0] - 1);
 			trim (to_string);
 
-			optional<FrameTime> from = time (from_string);
-			optional<FrameTime> to = time (to_string);
+			optional<Time> from = time (from_string);
+			optional<Time> to = time (to_string);
 
 			if (!from || !to) {
 				warn (String::compose ("Unrecognised line %1", line));
 				continue;
 			}
 
-			_subtitle.from.set_frame (from.get ());
-			_subtitle.to.set_frame (to.get ());
+			_subtitle.from = from.get ();
+			_subtitle.to = to.get ();
 
 			/* Parse ^B/^I/^U */
 			string text = line.substr (divider[1] + 1);
@@ -131,17 +132,17 @@ STLTextReader::STLTextReader (istream& in)
 	}
 }
 
-optional<FrameTime>
+optional<Time>
 STLTextReader::time (string t) const
 {
 	vector<string> b;
 	split (b, t, is_any_of (":"));
 	if (b.size() != 4) {
 		warn (String::compose ("Unrecognised time %1", t));
-		return optional<FrameTime> ();
+		return optional<Time> ();
 	}
 
-	return FrameTime (lexical_cast<int> (b[0]), lexical_cast<int> (b[1]), lexical_cast<int> (b[2]), lexical_cast<int> (b[3]));
+	return Time::from_hmsf (lexical_cast<int> (b[0]), lexical_cast<int> (b[1]), lexical_cast<int> (b[2]), lexical_cast<int> (b[3]), _frame_rate);
 }
 
 void
diff --git a/src/stl_text_reader.h b/src/stl_text_reader.h
index 77e9b73..026e38f 100644
--- a/src/stl_text_reader.h
+++ b/src/stl_text_reader.h
@@ -31,14 +31,15 @@ namespace sub {
 class STLTextReader : public Reader
 {
 public:
-	STLTextReader (std::istream &);
+	STLTextReader (std::istream &, sub::FrameRate frame_rate);
 
 private:
 	void set (std::string name, std::string value);
 	void maybe_push ();
-	boost::optional<FrameTime> time (std::string t) const;
+	boost::optional<Time> time (std::string t) const;
 
 	RawSubtitle _subtitle;
+	sub::FrameRate _frame_rate;
 };
 
 }
diff --git a/src/stl_util.cc b/src/stl_util.cc
index c145a34..2ee0100 100644
--- a/src/stl_util.cc
+++ b/src/stl_util.cc
@@ -26,40 +26,38 @@
 using std::string;
 using namespace sub;
 
-bool
-about_equal (float a, float b)
-{
-	return fabs (a - b) < 1e-4;
-}
-
 string
-sub::stl_frame_rate_to_dfc (float r)
+sub::stl_frame_rate_to_dfc (FrameRate r)
 {
 	/* This is the FAB Subtitler mapping, as used by Annotation Edit */
-	if (about_equal (r, 23.976)) {
+	switch (r) {
+	case TWENTY_THREE_DROP:
 		return "STL24.01";
-	} else if (about_equal (r, 24)) {
+	case TWENTY_FOUR:
 		return "STL23.01";
-	} else if (about_equal (r, 25)) {
+	case TWENTY_FIVE:
 		return "STL25.01";
-	} else if (about_equal (r, 30)) {
+	case THIRTY_DROP:
+		/* XXX: not right, but I don't think there is a value for this */
+		return "STL30.01";
+	case THIRTY:
 		return "STL30.01";
 	}
 
 	return "STL25.01";
 }
 
-float
+FrameRate
 sub::stl_dfc_to_frame_rate (string s)
 {
 	if (s == "STL24.01") {
-		return 23.976;
+		return TWENTY_THREE_DROP;
 	} else if (s == "STL23.01") {
-		return 24;
+		return TWENTY_FOUR;
 	} else if (s == "STL25.01") {
-		return 25;
+		return TWENTY_FIVE;
 	} else if (s == "STL30.01") {
-		return 30;
+		return THIRTY;
 	}
 
 	throw STLError (String::compose ("Unknown disk format code %1 in binary STL file", s));
diff --git a/src/stl_util.h b/src/stl_util.h
index 0da8215..a5c98ed 100644
--- a/src/stl_util.h
+++ b/src/stl_util.h
@@ -17,11 +17,12 @@
 
 */
 
+#include "frame_rate.h"
 #include <string>
 
 namespace sub {
 
-std::string stl_frame_rate_to_dfc (float r);
-float stl_dfc_to_frame_rate (std::string s);
+std::string stl_frame_rate_to_dfc (FrameRate r);
+FrameRate stl_dfc_to_frame_rate (std::string s);
 
 }
diff --git a/src/sub_time.cc b/src/sub_time.cc
new file mode 100644
index 0000000..780dbc9
--- /dev/null
+++ b/src/sub_time.cc
@@ -0,0 +1,196 @@
+/*
+    Copyright (C) 2015 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 "sub_time.h"
+#include "exceptions.h"
+#include <cmath>
+
+using std::ostream;
+using boost::optional;
+using namespace sub;
+
+/** @return The whole time as a number of milliseconds */
+int64_t
+Time::as_milliseconds () const
+{
+	if (_frames && !_frame_rate) {
+		throw UnknownFrameRateException ();
+	}
+	
+	int64_t s = (int64_t (hours) * 3600 + minutes * 60 + seconds) * 1000;
+	if (_frames) {
+		s += rint (_frames.get() * 1000 / enum_to_value (_frame_rate.get ()));
+	} else {
+		s += _milliseconds.get();
+	}
+	
+	return s;
+}
+
+int
+Time::frames (FrameRate r) const
+{
+	if (_frames && !_frame_rate) {
+		throw UnknownFrameRateException ();
+	}
+
+	if (_frames) {
+		if (_frame_rate == r) {
+			return _frames.get();
+		} else {
+			return rint (double (_frames.get()) * enum_to_value (r) / _frame_rate.get());
+		}
+	} else {
+		return rint (double (_milliseconds.get()) * enum_to_value (r) / 1000);
+	}
+}
+
+Time
+Time::from_hmsf (int h, int m, int s, int f)
+{
+	return Time (h, m, s, optional<int> (), f, optional<FrameRate> ());
+}
+
+Time
+Time::from_hmsf (int h, int m, int s, int f, sub::FrameRate r)
+{
+	return Time (h, m, s, optional<int> (), f, r);
+}
+
+Time
+Time::from_hms (int h, int m, double s)
+{
+	int const is = int (s);
+	return Time (h, m, is, rint ((s - is) * 1000), optional<int> (), optional<FrameRate> ());
+}
+
+Time
+Time::from_hmsm (int h, int m, int s, int ms)
+{
+	return Time (h, m, s, ms, optional<int> (), optional<FrameRate> ());
+}
+
+bool
+Time::operator< (Time const & other) const
+{
+	if ((_frames && !_frame_rate) || (other._frames && !other._frame_rate)) {
+		throw UnknownFrameRateException ();
+	}
+	    
+	if (hours != other.hours) {
+		return hours < other.hours;
+	}
+
+	if (minutes != other.minutes) {
+		return minutes < other.minutes;
+	}
+
+	if (seconds != other.seconds) {
+		return seconds < other.seconds;
+	}
+
+	/* Both frames with the same rate */
+	if (_frames && other._frames && _frame_rate.get() == other._frame_rate.get()) {
+		return _frames.get() < other._frames.get();
+	}
+			
+	/* Otherwise we have to do it by comparing milliseconds */
+	return as_milliseconds() < other.as_milliseconds();
+}
+	
+bool
+Time::operator> (Time const & other) const
+{
+	if ((_frames && !_frame_rate) || (other._frames && !other._frame_rate)) {
+		throw UnknownFrameRateException ();
+	}
+	    
+	if (hours != other.hours) {
+		return hours > other.hours;
+	}
+
+	if (minutes != other.minutes) {
+		return minutes > other.minutes;
+	}
+
+	if (seconds != other.seconds) {
+		return seconds > other.seconds;
+	}
+
+	/* Both frames with the same rate */
+	if (_frames && other._frames && _frame_rate.get() == other._frame_rate.get()) {
+		return _frames.get() > other._frames.get();
+	}
+			
+	/* Otherwise we have to do it by comparing milliseconds */
+	return as_milliseconds() > other.as_milliseconds();
+}
+
+bool
+Time::operator== (Time const & other) const
+{
+	if (hours != other.hours || minutes != other.minutes || seconds != other.seconds) {
+		return false;
+	}
+
+	if ((_frames && !_frame_rate) || (other._frames && !other._frame_rate)) {
+		throw UnknownFrameRateException ();
+	}
+
+	/* Both frames with the same rate */
+	if (_frames && other._frames && _frame_rate.get() == other._frame_rate.get()) {
+		return _frames.get() == other._frames.get();
+	}
+
+	/* Otherwise we have to do it by comparing milliseconds */
+	return abs (as_milliseconds() - other.as_milliseconds()) <= 1;
+}
+
+bool
+Time::operator!= (Time const & other) const
+{
+	return !(*this == other);
+}
+
+ostream &
+sub::operator<< (ostream& s, Time const & t)
+{
+	s << t.hours << "h " << t.minutes << "m " << t.seconds << "s ";
+	if (t._frames) {
+		s << t._frames.get() << "f";
+	}
+	if (t._frame_rate) {
+		s << " @ " << enum_to_value (t._frame_rate.get ());
+	}
+	if (t._milliseconds) {
+		s << t._milliseconds.get() << "ms";
+	}
+	return s;
+}
+
+Time::Time (int h, int m, int s, optional<int> ms, optional<int> f, optional<FrameRate> r)
+	: hours (h)
+	, minutes (m)
+	, seconds (s)
+	, _milliseconds (ms)
+	, _frames (f)
+	, _frame_rate (r)
+{
+
+}
diff --git a/src/sub_time.h b/src/sub_time.h
new file mode 100644
index 0000000..4b3f0e1
--- /dev/null
+++ b/src/sub_time.h
@@ -0,0 +1,75 @@
+/*
+    Copyright (C) 2015 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.
+
+*/
+
+#ifndef LIBSUB_SUB_TIME_H
+#define LIBSUB_SUB_TIME_H
+
+#include "frame_rate.h"
+#include <boost/optional.hpp>
+
+struct time_construction_test;
+
+namespace sub {
+
+class Time
+{
+public:
+	Time ()
+		: hours (0)
+		, minutes (0)
+		, seconds (0)
+	{}
+		  
+	int hours;
+	int minutes;
+	int seconds;
+
+	/** @return the frames part of the time at a particular frame rate */
+	int frames (FrameRate r) const;
+
+	/** @return the whole time in milliseconds */
+	int64_t as_milliseconds () const;
+
+	static Time from_hmsf (int h, int m, int s, int f);
+	static Time from_hmsf (int h, int m, int s, int f, FrameRate r);
+	static Time from_hms (int h, int m, double s);
+	static Time from_hmsm (int h, int m, int s, int ms);
+
+	bool operator== (Time const & other) const;
+	bool operator!= (Time const & other) const;
+	bool operator< (Time const & other) const;
+	bool operator> (Time const & other) const;
+
+private:
+	friend std::ostream & operator<< (std::ostream& s, Time const & t);
+
+	friend struct ::time_construction_test;
+	
+	Time (int h, int m, int s, boost::optional<int> ms, boost::optional<int> f, boost::optional<FrameRate> r);
+	
+	boost::optional<int> _milliseconds;
+	boost::optional<int> _frames;
+	boost::optional<FrameRate> _frame_rate;
+};
+	
+std::ostream& operator<< (std::ostream& s, Time const & t);
+	
+}
+
+#endif
diff --git a/src/subrip_reader.cc b/src/subrip_reader.cc
index 0aba120..20b234d 100644
--- a/src/subrip_reader.cc
+++ b/src/subrip_reader.cc
@@ -39,8 +39,8 @@ SubripReader::SubripReader (FILE* f)
 
 	char buffer[256];
 
-	TimePair from;
-	TimePair to;
+	Time from;
+	Time to;
 
 	string line;
 	int line_number = 0;
@@ -94,7 +94,7 @@ SubripReader::SubripReader (FILE* f)
 	}
 }
 
-TimePair
+Time
 SubripReader::convert_time (string t)
 {
 	vector<string> a;
@@ -106,18 +106,16 @@ SubripReader::convert_time (string t)
 	vector<string> b;
 	boost::algorithm::split (b, a[2], boost::is_any_of (","));
 
-	return TimePair (
-		MetricTime (
-			lexical_cast<int> (a[0]),
-			lexical_cast<int> (a[1]),
-			lexical_cast<int> (b[0]),
-			lexical_cast<int> (b[1])
-			)
+	return Time::from_hmsm (
+		lexical_cast<int> (a[0]),
+		lexical_cast<int> (a[1]),
+		lexical_cast<int> (b[0]),
+		lexical_cast<int> (b[1])
 		);
 }
 
 void
-SubripReader::convert_line (string t, int line_number, TimePair from, TimePair to)
+SubripReader::convert_line (string t, int line_number, Time from, Time to)
 {
 	enum {
 		TEXT,
diff --git a/src/subrip_reader.h b/src/subrip_reader.h
index 9b9ff92..a010f4a 100644
--- a/src/subrip_reader.h
+++ b/src/subrip_reader.h
@@ -21,7 +21,6 @@
 #define LIBSUB_SUBRIP_READER_H
 
 #include "reader.h"
-#include "time_pair.h"
 
 struct subrip_reader_convert_line_test;
 struct subrip_reader_convert_time_test;
@@ -39,8 +38,8 @@ private:
 	friend struct ::subrip_reader_convert_time_test;
 	SubripReader () {}
 	
-	static TimePair convert_time (std::string t);
-	void convert_line (std::string t, int line_number, TimePair from, TimePair to);
+	static Time convert_time (std::string t);
+	void convert_line (std::string t, int line_number, Time from, Time to);
 	void maybe_content (RawSubtitle& p);
 };
 
diff --git a/src/subtitle.cc b/src/subtitle.cc
index d828628..dc316c3 100644
--- a/src/subtitle.cc
+++ b/src/subtitle.cc
@@ -33,7 +33,27 @@ Subtitle::Subtitle (RawSubtitle s)
 bool
 Subtitle::same_metadata (RawSubtitle s) const
 {
-	return from == s.from && to == s.to && fade_up == s.fade_up && fade_down == s.fade_down;
+	if (from != s.from || to != s.to) {
+		return false;
+	}
+
+	if (fade_up && s.fade_up && fade_up.get() != s.fade_up.get()) {
+		return false;
+	}
+
+	if ((fade_up && !s.fade_up) || (!fade_up && s.fade_up)) {
+		return false;
+	}
+
+	if (fade_down && s.fade_down && fade_down.get() != s.fade_down.get()) {
+		return false;
+	}
+
+	if ((fade_down && !s.fade_down) || (!fade_down && s.fade_down)) {
+		return false;
+	}
+	
+	return true;
 }
 
 Line::Line (RawSubtitle s)
diff --git a/src/subtitle.h b/src/subtitle.h
index 71dff80..d747a60 100644
--- a/src/subtitle.h
+++ b/src/subtitle.h
@@ -20,12 +20,10 @@
 #ifndef LIBSUB_SUBTITLE_H
 #define LIBSUB_SUBTITLE_H
 
-#include "frame_time.h"
-#include "metric_time.h"
 #include "colour.h"
+#include "sub_time.h"
 #include "vertical_reference.h"
 #include "effect.h"
-#include "time_pair.h"
 #include "font_size.h"
 #include "vertical_position.h"
 #include "raw_subtitle.h"
@@ -106,12 +104,12 @@ public:
 	Subtitle (RawSubtitle s);
 	
 	/** from time */
-	TimePair from;
+	Time from;
 	/** to time */
-	TimePair to;
+	Time to;
 	
-	boost::optional<TimePair> fade_up;
-	boost::optional<TimePair> fade_down;
+	boost::optional<Time> fade_up;
+	boost::optional<Time> fade_down;
 
 	std::list<Line> lines;
 
diff --git a/src/time_pair.cc b/src/time_pair.cc
deleted file mode 100644
index 9bad713..0000000
--- a/src/time_pair.cc
+++ /dev/null
@@ -1,124 +0,0 @@
-/*
-    Copyright (C) 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.
-
-*/
-
-/** @file  src/time_pair.cc
- *  @brief TimePair class.
- */
-
-#include "time_pair.h"
-#include <cmath>
-
-using std::ostream;
-using namespace sub;
-
-FrameTime
-TimePair::frame (float fps) const
-{
-	if (_frame) {
-		return _frame.get ();
-	}
-
-	MetricTime const m = _metric.get ();
-	return FrameTime (m.hours(), m.minutes(), m.seconds(), rint (m.milliseconds() * fps / 1000));
-}
-
-MetricTime
-TimePair::metric (float fps) const
-{
-	if (_metric) {
-		return _metric.get ();
-	}
-
-	FrameTime const f = _frame.get ();
-	return MetricTime (f.hours(), f.minutes(), f.seconds(), rint (f.frames() * 1000 / fps));
-}
-
-void
-TimePair::add (FrameTime t, float fps)
-{
-	if (_frame) {
-		_frame.get().add (t, fps);
-	} else {
-		_metric.get().add (MetricTime (t.hours(), t.minutes(), t.seconds(), rint (t.frames() * 1000 / fps)));
-	}
-}
-
-void
-TimePair::scale (float f, float fps)
-{
-	if (_frame) {
-		_frame.get().scale (f, fps);
-	} else {
-		_metric.get().scale (f);
-	}
-}
-
-bool
-TimePair::operator== (TimePair const & other) const
-{
-	if (_metric && other._metric) {
-		return _metric.get() == other._metric.get();
-	} else if (_frame && other._frame) {
-		return _frame.get() == other._frame.get();
-	}
-
-	return false;
-}
-
-bool
-TimePair::operator< (TimePair const & other) const
-{
-	if (_metric && other._metric) {
-		return _metric.get() < other._metric.get();
-	} else if (_frame && other._frame) {
-		return _frame.get() < other._frame.get();
-	}
-
-	assert (false);
-}
-
-bool
-TimePair::operator<= (TimePair const & other) const
-{
-	return (*this == other || *this < other);
-}
-
-bool
-TimePair::operator> (TimePair const & other) const
-{
-	return (!(*this <= other));
-}
-
-bool
-TimePair::operator>= (TimePair const & other) const
-{
-	return !(*this < other);
-}
-
-ostream &
-sub::operator<< (ostream& s, TimePair const & t)
-{
-	if (t.frame ()) {
-		s << "[FRAME] " << t.frame().get();
-	} else {
-		s << "[METRIC]" << t.metric().get();
-	}
-
-	return s;
-}
diff --git a/src/time_pair.h b/src/time_pair.h
deleted file mode 100644
index f06edda..0000000
--- a/src/time_pair.h
+++ /dev/null
@@ -1,88 +0,0 @@
-/*
-    Copyright (C) 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.
-
-*/
-
-/** @file  src/time_pair.h
- *  @brief TimePair class.
- */
-
-#ifndef LIBSUB_TIME_PAIR_H
-#define LIBSUB_TIME_PAIR_H
-
-#include "frame_time.h"
-#include "metric_time.h"
-#include <boost/optional.hpp>
-
-namespace sub {
-
-/** @class TimePair
- *  @brief A time, expressed either in metric (h:m:s:ms) or frames (h:m:s:f).
- */
-class TimePair
-{
-public:
-	TimePair () {}
-	
-	TimePair (FrameTime t)
-		: _frame (t)
-	{}
-	
-	TimePair (MetricTime t)
-		: _metric (t)
-	{}
-	
-	void set_frame (FrameTime t) {
-		_frame = t;
-		_metric = boost::optional<MetricTime> ();
-	}
-
-	void set_metric (MetricTime t) {
-		_metric = t;
-		_frame = boost::optional<FrameTime> ();
-	}
-
-	boost::optional<FrameTime> frame () const {
-		return _frame;
-	}
-	
-	boost::optional<MetricTime> metric () const {
-		return _metric;
-	}
-	
-	FrameTime  frame  (float fps) const;
-	MetricTime metric (float fps) const;
-
-	void add (FrameTime t, float fps);
-	void scale (float f, float fps);
-
-	bool operator== (TimePair const & other) const;
-	bool operator< (TimePair const & other) const;
-	bool operator<= (TimePair const & other) const;
-	bool operator> (TimePair const & other) const;
-	bool operator>= (TimePair const & other) const;
-	
-private:
-	boost::optional<FrameTime> _frame;
-	boost::optional<MetricTime> _metric;
-};
-
-std::ostream& operator<< (std::ostream & s, TimePair const &);	
-
-}
-
-#endif
diff --git a/src/wscript b/src/wscript
index acb9bd6..b1a4ca4 100644
--- a/src/wscript
+++ b/src/wscript
@@ -15,11 +15,10 @@ def build(bld):
                  colour.cc
                  dcp_reader.cc
                  effect.cc
-                 frame_time.cc
+                 frame_rate.cc
                  interop_dcp_reader.cc
                  iso6937.cc
                  iso6937_tables.cc
-                 metric_time.cc
                  raw_subtitle.cc
                  reader.cc
                  reader_factory.cc
@@ -28,8 +27,8 @@ def build(bld):
                  stl_binary_writer.cc
                  stl_text_reader.cc
                  stl_util.cc
-                 time_pair.cc
                  smpte_dcp_reader.cc
+                 sub_time.cc
                  subrip_reader.cc
                  subtitle.cc
                  util.cc
@@ -48,8 +47,6 @@ def build(bld):
               dcp_reader.h
               effect.h
               font_size.h
-              frame_time.h
-              metric_time.h
               raw_subtitle.h
               reader.h
               reader_factory.h
@@ -59,7 +56,6 @@ def build(bld):
               stl_text_reader.h
               subrip_reader.h
               subtitle.h
-              time_pair.h
               vertical_position.h
               vertical_reference.h
               """
diff --git a/test/dcp_reader_test.cc b/test/dcp_reader_test.cc
index 902e09f..026677f 100644
--- a/test/dcp_reader_test.cc
+++ b/test/dcp_reader_test.cc
@@ -35,10 +35,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test1)
 
 	list<sub::Subtitle>::iterator i = subs.begin ();
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 5, 198 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 7, 115 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 4));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 5, 198 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 7, 115 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 4));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -61,10 +61,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test1)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 7, 177 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 11, 31 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 4));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 7, 177 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 11, 31 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 4));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -101,10 +101,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test1)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 11, 94 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 13, 63 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 4));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 11, 94 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 13, 63 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 4));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -127,10 +127,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test1)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 13, 104 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 15, 177 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 4));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 13, 104 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 15, 177 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 4));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 4));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -160,10 +160,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	list<sub::Subtitle>::iterator i = subs.begin ();
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 41, 62 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 43, 52 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 41, 62 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 43, 52 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -200,10 +200,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 		
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 0, 50, 42 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 0, 52, 21 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 50, 42 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 52, 21 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -240,10 +240,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 2, 208 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 4, 10 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 2, 208 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 4, 10 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -268,15 +268,15 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 		BOOST_CHECK_EQUAL (b.italic, true);
 		BOOST_CHECK (b.colour == sub::Colour (1, 1, 1));
 		BOOST_CHECK_EQUAL (b.font_size.proportional().get(), float (42) / (72 * 11));
-		BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 2, 208 * 4));
-		BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 4, 10 * 4));
+		BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 2, 208 * 4));
+		BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 4, 10 * 4));
 		BOOST_CHECK_CLOSE (j->vertical_position.proportional.get(), 0.95, 1);
 		BOOST_CHECK_EQUAL (j->vertical_position.reference.get(), sub::TOP_OF_SCREEN);
 		BOOST_CHECK_EQUAL (b.text, "I spent a long weekend in Brighton");
 		BOOST_CHECK_EQUAL (b.effect, sub::BORDER);
 		BOOST_CHECK (b.effect_colour.get() == sub::Colour (0, 0, 0));
-		BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-		BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+		BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+		BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 
 		++j;
 		BOOST_CHECK (j == i->lines.end ());
@@ -284,10 +284,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 15, 42 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 16, 42 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 15, 42 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 16, 42 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -324,10 +324,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 20, 219 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 22, 73 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));	
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 20, 219 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 22, 73 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));	
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -364,10 +364,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 27, 115 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 28, 208 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 27, 115 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 28, 208 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -404,10 +404,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 42, 229 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 45, 62 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 42, 229 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 45, 62 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -444,10 +444,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 45, 146 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 47, 94 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 45, 146 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 47, 94 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -484,10 +484,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 47, 146 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 48, 167 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 47, 146 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 48, 167 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -524,10 +524,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 		
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 1, 53, 21 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 1, 56, 10 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 53, 21 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 56, 10 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -564,10 +564,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test2)
 	
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from, sub::MetricTime (0, 2, 5, 208 * 4));
-	BOOST_CHECK_EQUAL (i->to, sub::MetricTime (0, 2, 7, 31 * 4));
-	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::MetricTime (0, 0, 0, 0));
-	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::MetricTime (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 2, 5, 208 * 4));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 2, 7, 31 * 4));
+	BOOST_CHECK_EQUAL (i->fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 0));
+	BOOST_CHECK_EQUAL (i->fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 0));
 	
 	{
 		list<sub::Line>::iterator j = i->lines.begin ();
@@ -611,10 +611,10 @@ BOOST_AUTO_TEST_CASE (dcp_reader_test3)
 
 	BOOST_REQUIRE_EQUAL (subs.size(), 1);
 	sub::Subtitle sub = subs.front ();
-	BOOST_REQUIRE_EQUAL (sub.from, sub::MetricTime (0, 0, 5, 198 * 4));
-	BOOST_REQUIRE_EQUAL (sub.to, sub::MetricTime (0, 0, 7, 115 * 4));
-	BOOST_REQUIRE_EQUAL (sub.fade_up.get(), sub::MetricTime (0, 0, 0, 4));
-	BOOST_REQUIRE_EQUAL (sub.fade_down.get(), sub::MetricTime (0, 0, 0, 4));
+	BOOST_REQUIRE_EQUAL (sub.from, sub::Time::from_hmsm (0, 0, 5, 198 * 4));
+	BOOST_REQUIRE_EQUAL (sub.to, sub::Time::from_hmsm (0, 0, 7, 115 * 4));
+	BOOST_REQUIRE_EQUAL (sub.fade_up.get(), sub::Time::from_hmsm (0, 0, 0, 4));
+	BOOST_REQUIRE_EQUAL (sub.fade_down.get(), sub::Time::from_hmsm (0, 0, 0, 4));
 	BOOST_REQUIRE_EQUAL (sub.lines.size(), 1);
 
 	sub::Line line = sub.lines.front ();
diff --git a/test/dcp_to_stl_binary_test.cc b/test/dcp_to_stl_binary_test.cc
index 6199c69..a3a7787 100644
--- a/test/dcp_to_stl_binary_test.cc
+++ b/test/dcp_to_stl_binary_test.cc
@@ -37,7 +37,7 @@ BOOST_AUTO_TEST_CASE (dcp_to_stl_binary_test1)
 	boost::filesystem::path p = private_test / "fd586c30-6d38-48f2-8241-27359acf184c_sub.xml";
 	sub::write_stl_binary (
 		sub::collect<list<sub::Subtitle> > (sub::InteropDCPReader(p).subtitles ()),
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_FRENCH,
 		"", "",
 		"", "",
@@ -64,7 +64,7 @@ BOOST_AUTO_TEST_CASE (dcp_to_stl_binary_test2)
 	boost::filesystem::path p = private_test / "93e8a6bf-499e-4d36-9350-a9bfa2e6758a_sub.xml";
 	sub::write_stl_binary (
 		sub::collect<list<sub::Subtitle> > (sub::InteropDCPReader(p).subtitles ()),
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_FRENCH,
 		"", "",
 		"", "",
@@ -91,7 +91,7 @@ BOOST_AUTO_TEST_CASE (dcp_to_stl_binary_test3)
 	boost::filesystem::path p = private_test / "Paddington_FTR_Subs_DE-FR_24fps_R1.xml";
 	sub::write_stl_binary (
 		sub::collect<list<sub::Subtitle> > (sub::InteropDCPReader(p).subtitles ()),
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_FRENCH,
 		"", "",
 		"", "",
@@ -113,7 +113,7 @@ BOOST_AUTO_TEST_CASE (dcp_to_stl_binary_test4)
 {
 	sub::write_stl_binary (
 		sub::collect<list<sub::Subtitle> > (sub::InteropDCPReader("test/data/test1.xml").subtitles ()),
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_FRENCH,
 		"", "",
 		"", "",
@@ -135,7 +135,7 @@ BOOST_AUTO_TEST_CASE (dcp_to_stl_binary_test5)
 	boost::filesystem::path p = private_test / "065d39ff-6723-4dbf-a94f-849cde82f5e1_sub.mxf";
 	sub::write_stl_binary (
 		sub::collect<list<sub::Subtitle> > (sub::SMPTEDCPReader(p, true).subtitles ()),
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_FRENCH,
 		"", "",
 		"", "",
diff --git a/test/stl_binary_writer_test.cc b/test/stl_binary_writer_test.cc
index 9bc3ec7..3596d73 100644
--- a/test/stl_binary_writer_test.cc
+++ b/test/stl_binary_writer_test.cc
@@ -30,8 +30,8 @@ BOOST_AUTO_TEST_CASE (stl_binary_writer_test)
 
 	{
 		sub::Subtitle s;
-		s.from.set_frame (sub::FrameTime (0, 0, 41, 9));
-		s.to.set_frame (sub::FrameTime (0, 0, 42, 21));
+		s.from = sub::Time::from_hmsf (0, 0, 41, 9, sub::TWENTY_FIVE);
+		s.to = sub::Time::from_hmsf (0, 0, 42, 21, sub::TWENTY_FIVE);
 
 		{
 			sub::Block b;
@@ -64,8 +64,8 @@ BOOST_AUTO_TEST_CASE (stl_binary_writer_test)
 
 	{
 		sub::Subtitle s;
-		s.from.set_frame (sub::FrameTime (0, 1, 1, 1));
-		s.to.set_frame (sub::FrameTime (0, 1, 2, 10));
+		s.from = sub::Time::from_hmsf (0, 1, 1, 1, sub::TWENTY_FIVE);
+		s.to = sub::Time::from_hmsf (0, 1, 2, 10, sub::TWENTY_FIVE);
 
 		sub::Line l;
 		l.vertical_position.line = 0;
@@ -97,7 +97,7 @@ BOOST_AUTO_TEST_CASE (stl_binary_writer_test)
 
 	sub::write_stl_binary (
 		subs,
-		25,
+		sub::TWENTY_FIVE,
 		sub::LANGUAGE_GERMAN,
 		"Original programme title",
 		"Original episode title",
diff --git a/test/stl_text_reader_test.cc b/test/stl_text_reader_test.cc
index c6f58b3..b99da2e 100644
--- a/test/stl_text_reader_test.cc
+++ b/test/stl_text_reader_test.cc
@@ -31,7 +31,7 @@ using std::vector;
 BOOST_AUTO_TEST_CASE (stl_text_reader_test)
 {
 	ifstream file ("test/data/test_text.stl");
-	sub::STLTextReader reader (file);
+	sub::STLTextReader reader (file, sub::TWENTY_FIVE);
 	list<sub::Subtitle> subs = sub::collect<list<sub::Subtitle> > (reader.subtitles ());
 
 	list<sub::Subtitle>::iterator i = subs.begin ();
@@ -40,8 +40,8 @@ BOOST_AUTO_TEST_CASE (stl_text_reader_test)
 	/* First subtitle */
 
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.frame().get(), sub::FrameTime (0, 0, 41, 9));
-	BOOST_CHECK_EQUAL (i->to.frame().get(), sub::FrameTime (0, 0, 42, 21));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsf (0, 0, 41, 9, sub::TWENTY_FIVE));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsf (0, 0, 42, 21, sub::TWENTY_FIVE));
 	
 	list<sub::Line>::iterator j = i->lines.begin ();
 	BOOST_CHECK (j != i->lines.end ());
@@ -72,8 +72,8 @@ BOOST_AUTO_TEST_CASE (stl_text_reader_test)
 	/* Second subtitle */
 	
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.frame().get(), sub::FrameTime (0, 1, 1, 1));
-	BOOST_CHECK_EQUAL (i->to.frame().get(), sub::FrameTime (0, 1, 2, 10));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsf (0, 1, 1, 1, sub::TWENTY_FIVE));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsf (0, 1, 2, 10, sub::TWENTY_FIVE));
 	
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	sub::Line l = i->lines.front ();
diff --git a/test/subrip_reader_test.cc b/test/subrip_reader_test.cc
index decca01..ea629c6 100644
--- a/test/subrip_reader_test.cc
+++ b/test/subrip_reader_test.cc
@@ -44,8 +44,8 @@ BOOST_AUTO_TEST_CASE (subrip_reader_test)
 	/* First subtitle */
 
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 0, 41, 90));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 0, 42, 210));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 0, 41, 90));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 0, 42, 210));
 	
 	list<sub::Line>::iterator j = i->lines.begin ();
 	BOOST_CHECK (j != i->lines.end ());
@@ -78,8 +78,8 @@ BOOST_AUTO_TEST_CASE (subrip_reader_test)
 	/* Second subtitle */
 	
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 1, 1, 10));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 1, 2, 100));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 1, 10));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 2, 100));
 	
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	sub::Line l = i->lines.front ();
@@ -166,46 +166,46 @@ BOOST_AUTO_TEST_CASE (subrip_reader_test2)
 	list<sub::Subtitle>::const_iterator i = subs.begin();
 
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 1, 49, 200));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 1, 52, 351));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 49, 200));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 52, 351));
 	BOOST_CHECK_EQUAL (i->lines.size(), 2);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "This is a subtitle, and it goes ");
 	BOOST_CHECK_EQUAL (i->lines.back().blocks.front().text, "over two lines.");
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 1, 52, 440));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 1, 54, 351));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 52, 440));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 54, 351));
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "We have emboldened this");
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().bold, true);
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 1, 54, 440));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 1, 56, 590));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 54, 440));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 56, 590));
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "And italicised this.");
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().italic, true);
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 1, 56, 680));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 1, 58, 955));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 1, 56, 680));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 1, 58, 955));
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "Shall I compare thee to a summers' day?");
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 2, 0, 840));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 2, 3, 400));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 2, 0, 840));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 2, 3, 400));
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "Is this a dagger I see before me?");
 
 	++i;
 	BOOST_CHECK (i != subs.end ());
-	BOOST_CHECK_EQUAL (i->from.metric().get(), sub::MetricTime (0, 3, 54, 560));
-	BOOST_CHECK_EQUAL (i->to.metric().get(), sub::MetricTime (0, 3, 56, 471));
+	BOOST_CHECK_EQUAL (i->from, sub::Time::from_hmsm (0, 3, 54, 560));
+	BOOST_CHECK_EQUAL (i->to, sub::Time::from_hmsm (0, 3, 56, 471));
 	BOOST_CHECK_EQUAL (i->lines.size(), 1);
 	BOOST_CHECK_EQUAL (i->lines.front().blocks.front().text, "Hello world.");
 
@@ -218,48 +218,48 @@ BOOST_AUTO_TEST_CASE (subrip_reader_convert_line_test)
 {
 	sub::SubripReader r;
 	
-	r.convert_line ("Hello world", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("Hello world", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	r._subs.clear ();
 
-	r.convert_line ("<b>Hello world</b>", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("<b>Hello world</b>", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().bold, true);
 	r._subs.clear ();
 
-	r.convert_line ("<i>Hello world</i>", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("<i>Hello world</i>", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().italic, true);
 	r._subs.clear ();
 
-	r.convert_line ("<u>Hello world</u>", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("<u>Hello world</u>", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().underline, true);
 	r._subs.clear ();
 
-	r.convert_line ("{b}Hello world{/b}", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("{b}Hello world{/b}", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().bold, true);
 	r._subs.clear ();
 
-	r.convert_line ("{i}Hello world{/i}", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("{i}Hello world{/i}", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().italic, true);
 	r._subs.clear ();
 
-	r.convert_line ("{u}Hello world{/u}", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("{u}Hello world{/u}", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 1);
 	BOOST_CHECK_EQUAL (r._subs.front().text, "Hello world");
 	BOOST_CHECK_EQUAL (r._subs.front().underline, true);
 	r._subs.clear ();
 
-	r.convert_line ("<b>This is <i>nesting</i> of subtitles</b>", 0, sub::TimePair (), sub::TimePair ());
+	r.convert_line ("<b>This is <i>nesting</i> of subtitles</b>", 0, sub::Time (), sub::Time ());
 	BOOST_CHECK_EQUAL (r._subs.size(), 3);
 	list<sub::RawSubtitle>::iterator i = r._subs.begin ();	
 	BOOST_CHECK_EQUAL (i->text, "This is ");
@@ -281,8 +281,8 @@ BOOST_AUTO_TEST_CASE (subrip_reader_convert_line_test)
 /** Test SubripReader::convert_time */
 BOOST_AUTO_TEST_CASE (subrip_reader_convert_time_test)
 {
-	BOOST_CHECK_EQUAL (sub::SubripReader::convert_time ("00:03:10,500"), sub::TimePair (sub::MetricTime (0, 3, 10, 500)));
-	BOOST_CHECK_EQUAL (sub::SubripReader::convert_time ("04:19:51,782"), sub::TimePair (sub::MetricTime (4, 19, 51, 782)));
+	BOOST_CHECK_EQUAL (sub::SubripReader::convert_time ("00:03:10,500"), sub::Time::from_hmsm (0, 3, 10, 500));
+	BOOST_CHECK_EQUAL (sub::SubripReader::convert_time ("04:19:51,782"), sub::Time::from_hmsm (4, 19, 51, 782));
 }
 
 
diff --git a/test/time_test.cc b/test/time_test.cc
index d6ca14a..2179815 100644
--- a/test/time_test.cc
+++ b/test/time_test.cc
@@ -18,70 +18,40 @@
 */
 
 #include <boost/test/unit_test.hpp>
-#include "metric_time.h"
-#include "frame_time.h"
-#include "time_pair.h"
+#include "sub_time.h"
 
 /* Check time construction */
 BOOST_AUTO_TEST_CASE (time_construction_test)
 {
 	{
-		sub::MetricTime t (3, 5, 7, 40);
-		BOOST_CHECK_EQUAL (t.hours(), 3);
-		BOOST_CHECK_EQUAL (t.minutes(), 5);
-		BOOST_CHECK_EQUAL (t.seconds(), 7);
-		BOOST_CHECK_EQUAL (t.milliseconds(), 40);
+		sub::Time t = sub::Time::from_hmsm (3, 5, 7, 40);
+		BOOST_CHECK_EQUAL (t.hours, 3);
+		BOOST_CHECK_EQUAL (t.minutes, 5);
+		BOOST_CHECK_EQUAL (t.seconds, 7);
+		BOOST_CHECK_EQUAL (t._milliseconds.get(), 40);
 	}
 
 	{
-		sub::MetricTime t (591353, 1, 2, 3);
-		BOOST_CHECK_EQUAL (t.hours(), 591353);
-		BOOST_CHECK_EQUAL (t.minutes(), 1);
-		BOOST_CHECK_EQUAL (t.seconds(), 2);
-		BOOST_CHECK_EQUAL (t.milliseconds(), 3);
-	}
-
-	{
-		sub::FrameTime t (3 * 60 * 60 * 24 + 31 * 60 * 24 + 4 * 24 + 11, 24);
-		BOOST_CHECK_EQUAL (t.hours(), 3);
-		BOOST_CHECK_EQUAL (t.minutes(), 31);
-		BOOST_CHECK_EQUAL (t.seconds(), 4);
-		BOOST_CHECK_EQUAL (t.frames(), 11);
+		sub::Time t = sub::Time::from_hmsm (591353, 1, 2, 3);
+		BOOST_CHECK_EQUAL (t.hours, 591353);
+		BOOST_CHECK_EQUAL (t.minutes, 1);
+		BOOST_CHECK_EQUAL (t.seconds, 2);
+		BOOST_CHECK_EQUAL (t._milliseconds.get(), 3);
 	}
 }
 
 /* Check time conversions */
 BOOST_AUTO_TEST_CASE (time_conversion_test)
 {
-	sub::TimePair p;
-	
 	/* 40ms = 1 frame at 25fps */
-	p.set_metric (sub::MetricTime (3, 5, 7, 40));
-	BOOST_CHECK_EQUAL (p.frame (25), sub::FrameTime (3, 5, 7, 1));
-	p.set_frame (sub::FrameTime  (3, 5, 7, 1));
-	BOOST_CHECK_EQUAL (p.metric (25), sub::MetricTime (3, 5, 7, 40));
+	sub::Time p = sub::Time::from_hmsm (3, 5, 7, 40);
+	BOOST_CHECK_EQUAL (p.frames (sub::TWENTY_FIVE), 1);
+	p = sub::Time::from_hmsf (3, 5, 7, 1, sub::TWENTY_FIVE);
+	BOOST_CHECK_EQUAL (p.as_milliseconds(), sub::Time::from_hmsm (3, 5, 7, 40).as_milliseconds ());
 
 	/* 120ms = 3 frames at 25fps */
-	p.set_metric (sub::MetricTime (3, 5, 7, 120));
-	BOOST_CHECK_EQUAL (p.frame (25), sub::FrameTime (3, 5, 7, 3));
-	p.set_frame (sub::FrameTime (3, 5, 7, 3));
-	BOOST_CHECK_EQUAL (p.metric (25), sub::MetricTime (3, 5, 7, 120));
-}
-
-/* Check time maths */
-BOOST_AUTO_TEST_CASE (time_maths_test)
-{
-	{
-		sub::FrameTime a (1, 59, 59, 23);
-		sub::FrameTime b (2, 31, 19, 2);
-		a.add (b, 24);
-		BOOST_CHECK_EQUAL (a, sub::FrameTime (4, 31, 19, 1));
-	}
-
-	{
-		sub::MetricTime a (1, 59, 59, 999);
-		sub::MetricTime b (2, 31, 19, 2);
-		a.add (b);
-		BOOST_CHECK_EQUAL (a, sub::MetricTime (4, 31, 19, 1));
-	}
+	p = sub::Time::from_hmsm (3, 5, 7, 120);
+	BOOST_CHECK_EQUAL (p.frames (sub::TWENTY_FIVE), 3);
+	p = sub::Time::from_hmsf (3, 5, 7, 3, sub::TWENTY_FIVE);
+	BOOST_CHECK_EQUAL (p.as_milliseconds (), sub::Time::from_hmsm (3, 5, 7, 120).as_milliseconds ());
 }
diff --git a/tools/dumpsubs.cc b/tools/dumpsubs.cc
index fef3885..fe7350d 100644
--- a/tools/dumpsubs.cc
+++ b/tools/dumpsubs.cc
@@ -71,7 +71,7 @@ main (int argc, char* argv[])
 		exit (EXIT_FAILURE);
 	}
 
-	shared_ptr<Reader> reader = reader_factory (argv[optind]);
+	shared_ptr<Reader> reader = reader_factory (argv[optind], sub::TWENTY_FIVE);
 	if (!reader) {
 		cerr << argv[0] << ": could not read subtitle file " << argv[optind] << "\n";
 		exit (EXIT_FAILURE);