monster commit: transport mgmt changes from 2.X (omnibus edition); make slave use nframes64_t ; avoid crashes in Drags when commiting reversible transactions that do not exist

git-svn-id: svn://localhost/ardour2/branches/3.0@6034 d708f5d6-7413-0410-9779-e7cbd77b26cf

18 files changed, 418 insertions, 373 deletions

diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 3a980982c3..6ac36f98b6 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -132,8 +132,8 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 		Recording = 2
 	};
 
-	struct Event {
-		enum Type {
+        struct Event {
+	        enum Type {
 			SetTransportSpeed,
 			SetDiskstreamSpeed,
 			Locate,
@@ -148,78 +148,82 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 			SetSlaveSource,
 			Audition,
 			InputConfigurationChange,
-			SetAudioRange,
-			SetPlayRange,
-
+			SetPlayAudioRange,
+			
 			/* only one of each of these events can be queued at any one time */
-
+			
 			StopOnce,
 			AutoLoop
 		};
-
-		enum Action {
-			Add,
-			Remove,
-			Replace,
-			Clear
-		};
-
-		Type             type;
-		Action           action;
-		nframes_t        action_frame;
-		nframes_t        target_frame;
-		double           speed;
-
-		union {
-			void*        ptr;
-			bool         yes_or_no;
-			nframes_t    target2_frame;
-			SlaveSource  slave;
-			Route*       route;
-		};
-
-		std::list<AudioRange> audio_range;
-		std::list<MusicRange> music_range;
-
-		boost::shared_ptr<Region> region;
-
-		Event(Type t, Action a, nframes_t when, nframes_t where, double spd, bool yn = false)
+	    
+	         enum Action {
+			 Add,
+			 Remove,
+			 Replace,
+			 Clear
+		 };
+	    
+	    Type             type;
+	    Action           action;
+	    nframes64_t      action_frame;
+	    nframes64_t      target_frame;
+	    double           speed;
+	    
+	    union {
+		void*        ptr;
+		bool         yes_or_no;
+		nframes64_t  target2_frame;
+		SlaveSource  slave;
+		Route*       route;
+	    };
+
+	    union {
+		bool second_yes_or_no;
+	    };
+	    
+	    std::list<AudioRange> audio_range;
+	    std::list<MusicRange> music_range;
+	    
+	    boost::shared_ptr<Region> region;
+	    
+	    Event(Type t, Action a, nframes_t when, nframes_t where, double spd, bool yn = false, bool yn2 = false)
 			: type (t)
 			, action (a)
 			, action_frame (when)
 			, target_frame (where)
 			, speed (spd)
 			, yes_or_no (yn)
+			, second_yes_or_no (yn2)
 		{}
 
-		void set_ptr (void* p) {
-			ptr = p;
-		}
-
-		bool before (const Event& other) const {
-			return action_frame < other.action_frame;
-		}
-
-		bool after (const Event& other) const {
-			return action_frame > other.action_frame;
-		}
-
-		static bool compare (const Event *e1, const Event *e2) {
-			return e1->before (*e2);
-		}
-
-		void *operator new (size_t) {
-			return pool.alloc ();
-		}
-
-		void operator delete (void *ptr, size_t /*size*/) {
-			pool.release (ptr);
-		}
-
-		static const nframes_t Immediate = 0;
-
-		private:
-		static MultiAllocSingleReleasePool pool;
+	    void set_ptr (void* p) {
+		    ptr = p;
+	    }
+	    
+	    bool before (const Event& other) const {
+		    return action_frame < other.action_frame;
+	    }
+	    
+	    bool after (const Event& other) const {
+		    return action_frame > other.action_frame;
+	    }
+	    
+	    static bool compare (const Event *e1, const Event *e2) {
+		    return e1->before (*e2);
+	    }
+	    
+	    void *operator new (size_t) {
+		    return pool.alloc ();
+	    }
+	    
+	    void operator delete (void *ptr, size_t /*size*/) {
+		    pool.release (ptr);
+	    }
+	    
+	    static const nframes_t Immediate = 0;
+	    
+	private:
+	    static MultiAllocSingleReleasePool pool;
 	};
 
 	/* creating from an XML file */
@@ -375,9 +379,9 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	/* Transport mechanism signals */
 
 	sigc::signal<void> TransportStateChange; /* generic */
-	sigc::signal<void,nframes_t> PositionChanged; /* sent after any non-sequential motion */
+	sigc::signal<void,nframes64_t> PositionChanged; /* sent after any non-sequential motion */
 	sigc::signal<void> DurationChanged;
-	sigc::signal<void,nframes_t> Xrun;
+	sigc::signal<void,nframes64_t> Xrun;
 	sigc::signal<void> TransportLooped;
 
 	/** emitted when a locate has occurred */
@@ -388,7 +392,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 
 	void request_roll_at_and_return (nframes_t start, nframes_t return_to);
 	void request_bounded_roll (nframes_t start, nframes_t end);
-	void request_stop (bool abort = false);
+	void request_stop (bool abort = false, bool clear_state = false);
 	void request_locate (nframes_t frame, bool with_roll = false);
 
 	void request_play_loop (bool yn, bool leave_rolling = false);
@@ -406,7 +410,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	void request_diskstream_speed (Diskstream&, double speed);
 	void request_input_change_handling ();
 
-	bool locate_pending() const { return static_cast<bool>(post_transport_work&PostTransportLocate); }
+	bool locate_pending() const { return static_cast<bool>(post_transport_work()&PostTransportLocate); }
 	bool transport_locked () const;
 
 	int wipe ();
@@ -533,8 +537,8 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 
 	/* Time */
 
-	nframes_t transport_frame () const {return _transport_frame; }
-	nframes_t audible_frame () const;
+        nframes64_t transport_frame () const {return _transport_frame; }
+	nframes64_t audible_frame () const;
 	nframes64_t requested_return_frame() const { return _requested_return_frame; }
 
 	enum PullupFormat {
@@ -914,10 +918,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 
 	/* ranges */
 
-	void set_audio_range (std::list<AudioRange>&);
-	void set_music_range (std::list<MusicRange>&);
-
-	void request_play_range (bool yn, bool leave_rolling = false);
+	void request_play_range (std::list<AudioRange>*, bool leave_rolling = false);
 	bool get_play_range () const { return _play_range; }
 
 	/* buffers for gain and pan */
@@ -997,7 +998,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	nframes_t               _nominal_frame_rate;  //ignores audioengine setting, "native" SR
 	int                      transport_sub_state;
 	mutable gint            _record_status;
-	volatile nframes_t      _transport_frame;
+	volatile nframes64_t    _transport_frame;
 	Location*                end_location;
 	Location*                start_location;
 	Slave*                  _slave;
@@ -1010,7 +1011,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	CubicInterpolation          interpolation;
 
 	bool                     auto_play_legal;
-	nframes_t               _last_slave_transport_frame;
+	nframes64_t             _last_slave_transport_frame;
 	nframes_t                maximum_output_latency;
 	volatile nframes64_t    _requested_return_frame;
 	BufferSet*              _scratch_buffers;
@@ -1026,6 +1027,7 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	bool                    _non_soloed_outs_muted;
 	uint32_t                _listen_cnt;
 	bool                    _writable;
+	bool                    _was_seamless;
 
 	void set_worst_io_latencies ();
 	void set_worst_io_latencies_x (IOChange, void *) {
@@ -1180,7 +1182,8 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 		PostTransportScrub              = 0x8000,
 		PostTransportReverse            = 0x10000,
 		PostTransportInputChange        = 0x20000,
-		PostTransportCurveRealloc       = 0x40000
+		PostTransportCurveRealloc       = 0x40000,
+		PostTransportClearSubstate      = 0x80000
 	};
 
 	static const PostTransportWork ProcessCannotProceedMask =
@@ -1192,9 +1195,13 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 				PostTransportScrub|
 				PostTransportAudition|
 				PostTransportLocate|
-				PostTransportStop);
+				PostTransportStop|
+				PostTransportClearSubstate);
 
-	PostTransportWork post_transport_work;
+	gint _post_transport_work; /* accessed only atomic ops */
+	PostTransportWork post_transport_work() const        { return (PostTransportWork) g_atomic_int_get (&_post_transport_work); }
+	void set_post_transport_work (PostTransportWork ptw) { g_atomic_int_set (&_post_transport_work, (gint) ptw); }
+	void add_post_transport_work (PostTransportWork ptw);
 
 	uint32_t    cumulative_rf_motion;
 	uint32_t    rf_scale;
@@ -1337,8 +1344,8 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	int no_roll (nframes_t nframes);
 	int fail_roll (nframes_t nframes);
 
-	bool non_realtime_work_pending() const { return static_cast<bool>(post_transport_work); }
-	bool process_can_proceed() const { return !(post_transport_work & ProcessCannotProceedMask); }
+	bool non_realtime_work_pending() const { return static_cast<bool>(post_transport_work()); }
+	bool process_can_proceed() const { return !(post_transport_work() & ProcessCannotProceedMask); }
 
 	struct MIDIRequest {
 		enum Type {
@@ -1361,18 +1368,19 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 	void          change_midi_ports ();
 	int           use_config_midi_ports ();
 
-	void set_play_loop (bool yn, bool leave_rolling);
+	void set_play_loop (bool yn);
+	void unset_play_loop ();
 	void overwrite_some_buffers (Diskstream*);
 	void flush_all_inserts ();
 	int  micro_locate (nframes_t distance);
-	void locate (nframes_t, bool with_roll, bool with_flush, bool with_loop=false);
-	void start_locate (nframes_t, bool with_roll, bool with_flush, bool with_loop=false);
-	void force_locate (nframes_t frame, bool with_roll = false);
+        void locate (nframes64_t, bool with_roll, bool with_flush, bool with_loop=false, bool force=false);
+        void start_locate (nframes64_t, bool with_roll, bool with_flush, bool with_loop=false, bool force=false);
+	void force_locate (nframes64_t frame, bool with_roll = false);
 	void set_diskstream_speed (Diskstream*, double speed);
-	void set_transport_speed (double speed, bool abort = false);
-	void stop_transport (bool abort = false);
+        void set_transport_speed (double speed, bool abort = false, bool clear_state = false);
+	void stop_transport (bool abort = false, bool clear_state = false);
 	void start_transport ();
-	void realtime_stop (bool abort);
+	void realtime_stop (bool abort, bool clear_state);
 	void non_realtime_start_scrub ();
 	void non_realtime_set_speed ();
 	void non_realtime_locate ();
@@ -1619,8 +1627,8 @@ class Session : public PBD::StatefulDestructible, public boost::noncopyable
 
 	std::list<AudioRange> current_audio_range;
 	bool _play_range;
-	void set_play_range (bool yn, bool leave_rolling);
-	void setup_auto_play ();
+	void set_play_range (std::list<AudioRange>&, bool leave_rolling);
+	void unset_play_range ();
 
 	/* main outs */
 	uint32_t main_outs;
diff --git a/libs/ardour/ardour/slave.h b/libs/ardour/ardour/slave.h
index 0f005d6f1b..9036c97a27 100644
--- a/libs/ardour/ardour/slave.h
+++ b/libs/ardour/ardour/slave.h
@@ -107,7 +107,7 @@ class Slave {
 	 * @param position - The transport position requested
 	 * @return - The return value is currently ignored (see Session::follow_slave)
 	 */
-	virtual bool speed_and_position (double& speed, nframes_t& position) = 0;
+	virtual bool speed_and_position (double& speed, nframes64_t& position) = 0;
 
 	/**
 	 * reports to ARDOUR whether the Slave is currently synced to its external
@@ -161,13 +161,13 @@ class Slave {
 class ISlaveSessionProxy {
   public:
 	virtual TempoMap& tempo_map()                 const   { return *((TempoMap *) 0); }
-	virtual nframes_t frame_rate()                const   { return 0; }
-	virtual nframes_t audible_frame ()            const   { return 0; }
-	virtual nframes_t transport_frame ()          const   { return 0; }
-	virtual nframes_t frames_since_cycle_start () const   { return 0; }
-	virtual nframes_t frame_time ()               const   { return 0; }
+	virtual nframes_t   frame_rate()                const   { return 0; }
+	virtual nframes64_t audible_frame ()            const   { return 0; }
+	virtual nframes64_t transport_frame ()          const   { return 0; }
+	virtual nframes_t   frames_since_cycle_start () const   { return 0; }
+	virtual nframes64_t frame_time ()               const   { return 0; }
 
-	virtual void request_locate (nframes_t /*frame*/, bool with_roll = false) {
+	virtual void request_locate (nframes64_t /*frame*/, bool with_roll = false) {
 		(void) with_roll;
 	}
 	virtual void request_transport_speed (double /*speed*/)                   {}
@@ -181,14 +181,14 @@ class SlaveSessionProxy : public ISlaveSessionProxy {
   public:
 	SlaveSessionProxy(Session &s) : session(s) {}
 
-	TempoMap& tempo_map()                 const;
-	nframes_t frame_rate()                const;
-	nframes_t audible_frame ()            const;
-	nframes_t transport_frame ()          const;
-	nframes_t frames_since_cycle_start () const;
-	nframes_t frame_time ()               const;
+	TempoMap&   tempo_map()                 const;
+	nframes_t   frame_rate()                const;
+	nframes64_t audible_frame ()            const;
+	nframes64_t transport_frame ()          const;
+	nframes_t   frames_since_cycle_start () const;
+	nframes64_t frame_time ()               const;
 
-	void request_locate (nframes_t frame, bool with_roll = false);
+	void request_locate (nframes64_t frame, bool with_roll = false);
 	void request_transport_speed (double speed);
 };
 
@@ -211,7 +211,7 @@ class MTC_Slave : public Slave, public sigc::trackable {
 	~MTC_Slave ();
 
 	void rebind (MIDI::Port&);
-	bool speed_and_position (double&, nframes_t&);
+	bool speed_and_position (double&, nframes64_t&);
 
 	bool locked() const;
 	bool ok() const;
@@ -256,7 +256,7 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
 	~MIDIClock_Slave ();
 
 	void rebind (MIDI::Port&);
-	bool speed_and_position (double&, nframes_t&);
+	bool speed_and_position (double&, nframes64_t&);
 
 	bool locked() const;
 	bool ok() const;
@@ -311,17 +311,17 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
 	double b, c, omega;
 
 	void reset ();
-	void start (MIDI::Parser& parser, nframes_t timestamp);
-	void contineu (MIDI::Parser& parser, nframes_t timestamp);
-	void stop (MIDI::Parser& parser, nframes_t timestamp);
+	void start (MIDI::Parser& parser, nframes64_t timestamp);
+	void contineu (MIDI::Parser& parser, nframes64_t timestamp);
+	void stop (MIDI::Parser& parser, nframes64_t timestamp);
 	void position (MIDI::Parser& parser, MIDI::byte* message, size_t size);
 	// we can't use continue because it is a C++ keyword
-	void calculate_one_ppqn_in_frames_at(nframes_t time);
-	nframes_t calculate_song_position(uint16_t song_position_in_sixteenth_notes);
+	void calculate_one_ppqn_in_frames_at(nframes64_t time);
+	nframes64_t calculate_song_position(uint16_t song_position_in_sixteenth_notes);
 	void calculate_filter_coefficients();
-	void update_midi_clock (MIDI::Parser& parser, nframes_t timestamp);
+	void update_midi_clock (MIDI::Parser& parser, nframes64_t timestamp);
 	void read_current (SafeTime *) const;
-	bool stop_if_no_more_clock_events(nframes_t& pos, nframes_t now);
+	bool stop_if_no_more_clock_events(nframes64_t& pos, nframes64_t now);
 
 	/// whether transport should be rolling
 	bool _started;
@@ -337,7 +337,7 @@ class ADAT_Slave : public Slave
 	ADAT_Slave () {}
 	~ADAT_Slave () {}
 
-	bool speed_and_position (double& speed, nframes_t& pos) {
+	bool speed_and_position (double& speed, nframes64_t& pos) {
 		speed = 0;
 		pos = 0;
 		return false;
@@ -355,7 +355,7 @@ class JACK_Slave : public Slave
 	JACK_Slave (jack_client_t*);
 	~JACK_Slave ();
 
-	bool speed_and_position (double& speed, nframes_t& pos);
+	bool speed_and_position (double& speed, nframes64_t& pos);
 
 	bool starting() const { return _starting; }
 	bool locked() const;
diff --git a/libs/ardour/audio_diskstream.cc b/libs/ardour/audio_diskstream.cc
index fbd10b92e3..3248cd9b2d 100644
--- a/libs/ardour/audio_diskstream.cc
+++ b/libs/ardour/audio_diskstream.cc
@@ -626,6 +626,7 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, bool can
 				nframes_t total = chaninfo->playback_vector.len[0] + chaninfo->playback_vector.len[1];
 
 				if (necessary_samples > total) {
+					cerr << _name << " Need " << necessary_samples << " total = " << total << endl;
 					cerr << "underrun for " << _name << endl;
 					DiskUnderrun ();
 					goto out;
@@ -1754,7 +1755,7 @@ AudioDiskstream::get_state ()
 		if (_session.config.get_punch_in() && ((pi = _session.locations()->auto_punch_location()) != 0)) {
 			snprintf (buf, sizeof (buf), "%" PRId64, pi->start());
 		} else {
-			snprintf (buf, sizeof (buf), "%" PRIu32, _session.transport_frame());
+			snprintf (buf, sizeof (buf), "%" PRId64, _session.transport_frame());
 		}
 
 		cs_child->add_property (X_("at"), buf);
diff --git a/libs/ardour/enums.cc b/libs/ardour/enums.cc
index 8ab2a6f8cf..885ebeb27a 100644
--- a/libs/ardour/enums.cc
+++ b/libs/ardour/enums.cc
@@ -299,8 +299,7 @@ setup_enum_writer ()
 	REGISTER_CLASS_ENUM (Session::Event, SetSlaveSource);
 	REGISTER_CLASS_ENUM (Session::Event, Audition);
 	REGISTER_CLASS_ENUM (Session::Event, InputConfigurationChange);
-	REGISTER_CLASS_ENUM (Session::Event, SetAudioRange);
-	REGISTER_CLASS_ENUM (Session::Event, SetPlayRange);
+	REGISTER_CLASS_ENUM (Session::Event, SetPlayAudioRange);
 	REGISTER_CLASS_ENUM (Session::Event, StopOnce);
 	REGISTER_CLASS_ENUM (Session::Event, AutoLoop);
 	REGISTER (_Session_Event_Type);
diff --git a/libs/ardour/filesystem_paths.cc b/libs/ardour/filesystem_paths.cc
index 2f2afe3c7b..932416ef41 100644
--- a/libs/ardour/filesystem_paths.cc
+++ b/libs/ardour/filesystem_paths.cc
@@ -16,6 +16,7 @@
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
 */
+#include <cstdlib>
 
 #include "pbd/error.h"
 #include "pbd/filesystem_paths.h"
@@ -36,18 +37,30 @@ using std::string;
 sys::path
 user_config_directory ()
 {
-	const string home_dir = Glib::get_home_dir ();
-
-	if (home_dir.empty ()) {
-		const string error_msg = "Unable to determine home directory";
-
-		// log the error
-		error << error_msg << endmsg;
-
-		throw sys::filesystem_error(error_msg);
+	const char* c = 0;
+	sys::path p;
+
+	/* adopt freedesktop standards, and put .ardour3 into $XDG_CONFIG_HOME or ~/.config
+	 */
+
+	if ((c = getenv ("XDG_CONFIG_HOME")) != 0) {
+		p = c;
+	} else {
+		const string home_dir = Glib::get_home_dir();
+	
+		if (home_dir.empty ()) {
+			const string error_msg = "Unable to determine home directory";
+			
+			// log the error
+			error << error_msg << endmsg;
+			
+			throw sys::filesystem_error(error_msg);
+		}
+
+		p = home_dir;
+		p /= ".config";
 	}
-
-	sys::path p(home_dir);
+	
 	p /= user_config_dir_name;
 
 	return p;
diff --git a/libs/ardour/jack_slave.cc b/libs/ardour/jack_slave.cc
index 9f92f1b21f..0f425d09c6 100644
--- a/libs/ardour/jack_slave.cc
+++ b/libs/ardour/jack_slave.cc
@@ -36,7 +36,7 @@ JACK_Slave::JACK_Slave (jack_client_t* j)
 	: jack (j)
 {
 	double x;
-	nframes_t p;
+	nframes64_t p;
 	/* call this to initialize things */
 	speed_and_position (x, p);
 }
@@ -64,10 +64,11 @@ JACK_Slave::ok() const
 }
 
 bool
-JACK_Slave::speed_and_position (double& sp, nframes_t& position)
+JACK_Slave::speed_and_position (double& sp, nframes64_t& position)
 {
 	jack_position_t pos;
 	jack_transport_state_t state;
+
 	state = jack_transport_query (jack, &pos);
 
 	switch (state) {
diff --git a/libs/ardour/midi_clock_slave.cc b/libs/ardour/midi_clock_slave.cc
index a41864571d..53f819e54a 100644
--- a/libs/ardour/midi_clock_slave.cc
+++ b/libs/ardour/midi_clock_slave.cc
@@ -87,7 +87,7 @@ MIDIClock_Slave::rebind (MIDI::Port& p)
 }
 
 void
-MIDIClock_Slave::calculate_one_ppqn_in_frames_at(nframes_t time)
+MIDIClock_Slave::calculate_one_ppqn_in_frames_at(nframes64_t time)
 {
 	const Tempo& current_tempo = session->tempo_map().tempo_at(time);
 	const Meter& current_meter = session->tempo_map().meter_at(time);
@@ -101,14 +101,14 @@ MIDIClock_Slave::calculate_one_ppqn_in_frames_at(nframes_t time)
 	one_ppqn_in_frames = frames_per_quarter_note / double (ppqn);
 }
 
-ARDOUR::nframes_t
+ARDOUR::nframes64_t
 MIDIClock_Slave::calculate_song_position(uint16_t song_position_in_sixteenth_notes)
 {
-	nframes_t song_position_frames = 0;
+	nframes64_t song_position_frames = 0;
 	for (uint16_t i = 1; i <= song_position_in_sixteenth_notes; ++i) {
 		// one quarter note contains ppqn pulses, so a sixteenth note is ppqn / 4 pulses
 		calculate_one_ppqn_in_frames_at(song_position_frames);
-		song_position_frames += one_ppqn_in_frames * nframes_t(ppqn / 4);
+		song_position_frames += one_ppqn_in_frames * (nframes64_t)(ppqn / 4);
 	}
 
 	return song_position_frames;
@@ -124,7 +124,7 @@ MIDIClock_Slave::calculate_filter_coefficients()
 }
 
 void
-MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, nframes_t timestamp)
+MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, nframes64_t timestamp)
 {
 	// some pieces of hardware send MIDI Clock all the time
 	if ( (!_starting) && (!_started) ) {
@@ -133,7 +133,7 @@ MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, nframes_t timestamp)
 
 	calculate_one_ppqn_in_frames_at(should_be_position);
 
-	nframes_t elapsed_since_start = timestamp - first_timestamp;
+	nframes64_t elapsed_since_start = timestamp - first_timestamp;
 	double error = 0;
 
 	if (_starting || last_timestamp == 0) {
@@ -195,7 +195,7 @@ MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, nframes_t timestamp)
 }
 
 void
-MIDIClock_Slave::start (Parser& /*parser*/, nframes_t /*timestamp*/)
+MIDIClock_Slave::start (Parser& /*parser*/, nframes64_t /*timestamp*/)
 {
 	#ifdef DEBUG_MIDI_CLOCK
 		cerr << "MIDIClock_Slave got start message at time "  <<  timestamp << " engine time: " << session->frame_time() << endl;
@@ -223,7 +223,7 @@ MIDIClock_Slave::reset ()
 }
 
 void
-MIDIClock_Slave::contineu (Parser& /*parser*/, nframes_t /*timestamp*/)
+MIDIClock_Slave::contineu (Parser& /*parser*/, nframes64_t /*timestamp*/)
 {
 	#ifdef DEBUG_MIDI_CLOCK
 		std::cerr << "MIDIClock_Slave got continue message" << endl;
@@ -236,7 +236,7 @@ MIDIClock_Slave::contineu (Parser& /*parser*/, nframes_t /*timestamp*/)
 
 
 void
-MIDIClock_Slave::stop (Parser& /*parser*/, nframes_t /*timestamp*/)
+MIDIClock_Slave::stop (Parser& /*parser*/, nframes64_t /*timestamp*/)
 {
 	#ifdef DEBUG_MIDI_CLOCK
 		std::cerr << "MIDIClock_Slave got stop message" << endl;
@@ -255,7 +255,7 @@ MIDIClock_Slave::stop (Parser& /*parser*/, nframes_t /*timestamp*/)
 		// that is the position of the last MIDI Clock
 		// message and that is probably what the master
 		// expects where we are right now
-		nframes_t stop_position = should_be_position;
+		nframes64_t stop_position = should_be_position;
 
 		// find out the last MIDI beat: go back #midi_clocks mod 6
 		// and lets hope the tempo didnt change in those last 6 beats :)
@@ -282,7 +282,7 @@ MIDIClock_Slave::position (Parser& /*parser*/, byte* message, size_t size)
 	assert((lsb <= 0x7f) && (msb <= 0x7f));
 
 	uint16_t position_in_sixteenth_notes = (uint16_t(msb) << 7) | uint16_t(lsb);
-	nframes_t position_in_frames = calculate_song_position(position_in_sixteenth_notes);
+	nframes64_t position_in_frames = calculate_song_position(position_in_sixteenth_notes);
 
 	#ifdef DEBUG_MIDI_CLOCK
 	cerr << "Song Position: " << position_in_sixteenth_notes << " frames: " << position_in_frames << endl;
@@ -313,7 +313,7 @@ MIDIClock_Slave::starting() const
 }
 
 bool
-MIDIClock_Slave::stop_if_no_more_clock_events(nframes_t& pos, nframes_t now)
+MIDIClock_Slave::stop_if_no_more_clock_events(nframes64_t& pos, nframes64_t now)
 {
 	/* no timecode for 1/4 second ? conclude that its stopped */
 	if (last_timestamp &&
@@ -332,7 +332,7 @@ MIDIClock_Slave::stop_if_no_more_clock_events(nframes_t& pos, nframes_t now)
 }
 
 bool
-MIDIClock_Slave::speed_and_position (double& speed, nframes_t& pos)
+MIDIClock_Slave::speed_and_position (double& speed, nframes64_t& pos)
 {
 	if (!_started || _starting) {
 		speed = 0.0;
@@ -340,7 +340,7 @@ MIDIClock_Slave::speed_and_position (double& speed, nframes_t& pos)
 		return true;
 	}
 
-	nframes_t engine_now = session->frame_time();
+	nframes64_t engine_now = session->frame_time();
 
 	if (stop_if_no_more_clock_events(pos, engine_now)) {
 		return false;
@@ -353,8 +353,8 @@ MIDIClock_Slave::speed_and_position (double& speed, nframes_t& pos)
 	if (engine_now > last_timestamp) {
 		// we are in between MIDI clock messages
 		// so we interpolate position according to speed
-		nframes_t elapsed = engine_now - last_timestamp;
-		pos = nframes_t (should_be_position + double(elapsed) * speed);
+		nframes64_t elapsed = engine_now - last_timestamp;
+		pos = (nframes64_t) (should_be_position + double(elapsed) * speed);
 	} else {
 		// A new MIDI clock message has arrived this cycle
 		pos = should_be_position;
diff --git a/libs/ardour/midi_diskstream.cc b/libs/ardour/midi_diskstream.cc
index f61211def8..f06b00ae00 100644
--- a/libs/ardour/midi_diskstream.cc
+++ b/libs/ardour/midi_diskstream.cc
@@ -1223,7 +1223,7 @@ MidiDiskstream::get_state ()
 		if (_session.config.get_punch_in() && ((pi = _session.locations()->auto_punch_location()) != 0)) {
 			snprintf (buf, sizeof (buf), "%" PRId64, pi->start());
 		} else {
-			snprintf (buf, sizeof (buf), "%" PRIu32, _session.transport_frame());
+			snprintf (buf, sizeof (buf), "%" PRId64, _session.transport_frame());
 		}
 
 		cs_child->add_property (X_("at"), buf);
diff --git a/libs/ardour/mtc_slave.cc b/libs/ardour/mtc_slave.cc
index 4034ef32be..3619cc4c69 100644
--- a/libs/ardour/mtc_slave.cc
+++ b/libs/ardour/mtc_slave.cc
@@ -72,7 +72,7 @@ void
 MTC_Slave::update_mtc_qtr (Parser& /*p*/)
 {
 	cycles_t cnow = get_cycles ();
-	nframes_t now = session.engine().frame_time();
+	nframes64_t now = session.engine().frame_time();
 	nframes_t qtr;
 	static cycles_t last_qtr = 0;
 
@@ -91,7 +91,7 @@ MTC_Slave::update_mtc_qtr (Parser& /*p*/)
 void
 MTC_Slave::update_mtc_time (const byte *msg, bool was_full)
 {
-	nframes_t now = session.engine().frame_time();
+	nframes64_t now = session.engine().frame_time();
 	Timecode::Time timecode;
 
 	timecode.hours = msg[3];
@@ -258,9 +258,9 @@ MTC_Slave::ok() const
 }
 
 bool
-MTC_Slave::speed_and_position (double& speed, nframes_t& pos)
+MTC_Slave::speed_and_position (double& speed, nframes64_t& pos)
 {
-	nframes_t now = session.engine().frame_time();
+	nframes64_t now = session.engine().frame_time();
 	SafeTime last;
 	nframes_t frame_rate;
 	nframes_t elapsed;
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 031c2aa58a..8b3d832204 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -132,7 +132,6 @@ Session::Session (AudioEngine &eng,
 	  pending_events (2048),
 	  state_tree (0),
 	  _butler (new Butler (this)),
-	  post_transport_work((PostTransportWork)0),
 	  _send_timecode_update (false),
 	  midi_thread (pthread_t (0)),
 	  midi_requests (128), // the size of this should match the midi request pool size
@@ -218,7 +217,6 @@ Session::Session (AudioEngine &eng,
 	  pending_events (2048),
 	  state_tree (0),
 	  _butler (new Butler (this)),
-	  post_transport_work((PostTransportWork)0),
 	  _send_timecode_update (false),
 	  midi_thread (pthread_t (0)),
 	  midi_requests (16),
@@ -1229,12 +1227,12 @@ Session::maybe_enable_record ()
 	set_dirty();
 }
 
-nframes_t
+nframes64_t
 Session::audible_frame () const
 {
-	nframes_t ret;
+	nframes64_t ret;
+	nframes64_t tf;
 	nframes_t offset;
-	nframes_t tf;
 
 	/* the first of these two possible settings for "offset"
 	   mean that the audible frame is stationary until
@@ -3517,7 +3515,7 @@ void
 Session::set_audition (boost::shared_ptr<Region> r)
 {
 	pending_audition_region = r;
-	post_transport_work = PostTransportWork (post_transport_work | PostTransportAudition);
+	add_post_transport_work (PostTransportAudition);
 	_butler->schedule_transport_work ();
 }
 
diff --git a/libs/ardour/session_butler.cc b/libs/ardour/session_butler.cc
index 41b4851ce5..0ffc14ff3a 100644
--- a/libs/ardour/session_butler.cc
+++ b/libs/ardour/session_butler.cc
@@ -68,7 +68,7 @@ static inline uint32_t next_power_of_two (uint32_t n)
 void
 Session::schedule_curve_reallocation ()
 {
-	post_transport_work = PostTransportWork (post_transport_work | PostTransportCurveRealloc);
+	add_post_transport_work (PostTransportCurveRealloc);
 	_butler->schedule_transport_work ();
 }
 
@@ -100,7 +100,7 @@ Session::overwrite_some_buffers (Diskstream* ds)
 		}
 	}
 
-	post_transport_work = PostTransportWork (post_transport_work | PostTransportOverWrite);
+	add_post_transport_work (PostTransportOverWrite);
 	_butler->schedule_transport_work ();
 }
 
diff --git a/libs/ardour/session_events.cc b/libs/ardour/session_events.cc
index 65635b773f..fb993faa68 100644
--- a/libs/ardour/session_events.cc
+++ b/libs/ardour/session_events.cc
@@ -23,6 +23,7 @@
 #include "ardour/timestamps.h"
 
 #include "pbd/error.h"
+#include "pbd/enumwriter.h"
 #include <glibmm/thread.h>
 
 #include "ardour/ardour.h"
@@ -38,28 +39,6 @@ using namespace PBD;
 
 MultiAllocSingleReleasePool Session::Event::pool ("event", sizeof (Session::Event), 512);
 
-static const char* event_names[] = {
-	"SetTransportSpeed",
-	"SetDiskstreamSpeed",
-	"Locate",
-	"LocateRoll",
-	"LocateRollLocate",
-	"SetLoop",
-	"PunchIn",
-	"PunchOut",
-	"RangeStop",
-	"RangeLocate",
-	"Overwrite",
-	"SetSlaveSource",
-	"Audition",
-	"InputConfigurationChange",
-	"SetAudioRange",
-	"SetMusicRange",
-	"SetPlayRange",
-	"StopOnce",
-	"AutoLoop"
-};
-
 void
 Session::add_event (nframes_t frame, Event::Type type, nframes_t target_frame)
 {
@@ -161,7 +140,7 @@ Session::merge_event (Event* ev)
 		for (Events::iterator i = events.begin(); i != events.end(); ++i) {
 			if ((*i)->type == ev->type && (*i)->action_frame == ev->action_frame) {
 			  error << string_compose(_("Session: cannot have two events of type %1 at the same frame (%2)."),
-						 event_names[ev->type], ev->action_frame) << endmsg;
+						  enum_2_string (ev->type), ev->action_frame) << endmsg;
 				return;
 			}
 		}
@@ -321,7 +300,7 @@ Session::process_event (Event* ev)
 
 	switch (ev->type) {
 	case Event::SetLoop:
-		set_play_loop (ev->yes_or_no, (ev->speed == 1.0f));
+		set_play_loop (ev->yes_or_no);
 		break;
 
 	case Event::AutoLoop:
@@ -362,7 +341,7 @@ Session::process_event (Event* ev)
 
 
 	case Event::SetTransportSpeed:
-		set_transport_speed (ev->speed, ev->yes_or_no);
+		set_transport_speed (ev->speed, ev->yes_or_no, ev->second_yes_or_no);
 		break;
 
 	case Event::PunchIn:
@@ -425,17 +404,12 @@ Session::process_event (Event* ev)
 		break;
 
 	case Event::InputConfigurationChange:
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportInputChange);
+		add_post_transport_work (PostTransportInputChange);
 		_butler->schedule_transport_work ();
 		break;
 
-	case Event::SetAudioRange:
-		current_audio_range = ev->audio_range;
-		setup_auto_play ();
-		break;
-
-	case Event::SetPlayRange:
-		set_play_range (ev->yes_or_no, (ev->speed == 1.0f));
+	case Event::SetPlayAudioRange:
+		set_play_range (ev->audio_range, (ev->speed == 1.0f));
 		break;
 
 	default:
diff --git a/libs/ardour/session_export.cc b/libs/ardour/session_export.cc
index 3eda11bab7..0bf87591cd 100644
--- a/libs/ardour/session_export.cc
+++ b/libs/ardour/session_export.cc
@@ -210,7 +210,7 @@ Session::stop_audio_export ()
 	   stuff that stop_transport() implements.
 	*/
 
-	realtime_stop (true);
+	realtime_stop (true, true);
 	_butler->schedule_transport_work ();
 
 	if (!export_status->aborted()) {
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index ea63e71307..4bbe852687 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -480,7 +480,7 @@ bool
 Session::follow_slave (nframes_t nframes)
 {
 	double slave_speed;
-	nframes_t slave_transport_frame;
+	nframes64_t slave_transport_frame;
 	nframes_t this_delta;
 	int dir;
 	bool starting;
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index f60cf8e85f..1a4758186e 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -197,11 +197,10 @@ Session::first_stage_init (string fullpath, string snapshot_name)
 	_worst_input_latency = 0;
  	_worst_track_latency = 0;
 	_state_of_the_state = StateOfTheState(CannotSave|InitialConnecting|Loading);
-
+	_was_seamless = Config->get_seamless_loop ();
 	_slave = 0;
 	session_send_mmc = false;
 	session_send_mtc = false;
-	post_transport_work = PostTransportWork (0);
 	g_atomic_int_set (&_playback_load, 100);
 	g_atomic_int_set (&_capture_load, 100);
 	g_atomic_int_set (&_playback_load_min, 100);
diff --git a/libs/ardour/session_time.cc b/libs/ardour/session_time.cc
index 9a6eebbaf8..1e1ecd3ed9 100644
--- a/libs/ardour/session_time.cc
+++ b/libs/ardour/session_time.cc
@@ -452,7 +452,7 @@ Session::jack_sync_callback (jack_transport_state_t state,
 
 	switch (state) {
 	case JackTransportStopped:
-		if (slave && _transport_frame != pos->frame && post_transport_work == 0) {
+		if (slave && _transport_frame != pos->frame && post_transport_work() == 0) {
 			request_locate (pos->frame, false);
 			// cerr << "SYNC: stopped, locate to " << pos->frame << " from " << _transport_frame << endl;
 			return false;
@@ -461,9 +461,9 @@ Session::jack_sync_callback (jack_transport_state_t state,
 		}
 
 	case JackTransportStarting:
-		// cerr << "SYNC: starting @ " << pos->frame << " a@ " << _transport_frame << " our work = " <<  post_transport_work << " pos matches ? " << (_transport_frame == pos->frame) << endl;
+		// cerr << "SYNC: starting @ " << pos->frame << " a@ " << _transport_frame << " our work = " <<  post_transport_work() << " pos matches ? " << (_transport_frame == pos->frame) << endl;
 		if (slave) {
-			return _transport_frame == pos->frame && post_transport_work == 0;
+			return _transport_frame == pos->frame && post_transport_work() == 0;
 		} else {
 			return true;
 		}
diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc
index 16ba54a369..10429e9639 100644
--- a/libs/ardour/session_transport.cc
+++ b/libs/ardour/session_transport.cc
@@ -51,6 +51,25 @@ using namespace sigc;
 using namespace PBD;
 
 void
+Session::add_post_transport_work (PostTransportWork ptw)
+{
+	PostTransportWork oldval;
+	PostTransportWork newval;
+	int tries = 0;
+
+	while (tries < 8) {
+		oldval = (PostTransportWork) g_atomic_int_get (&_post_transport_work);
+		newval = PostTransportWork (oldval | ptw);
+		if (g_atomic_int_compare_and_exchange (&_post_transport_work, oldval, newval)) {
+			/* success */
+			return;
+		}
+	}
+
+	error << "Could not set post transport work! Crazy thread madness, call the programmers" << endmsg;
+}
+
+void
 Session::request_input_change_handling ()
 {
 	if (!(_state_of_the_state & (InitialConnecting|Deletion))) {
@@ -63,12 +82,21 @@ void
 Session::request_slave_source (SlaveSource src)
 {
 	Event* ev = new Event (Event::SetSlaveSource, Event::Add, Event::Immediate, 0, 0.0);
+	bool seamless;
+
+	seamless = Config->get_seamless_loop ();
 
 	if (src == JACK) {
-		/* could set_seamless_loop() be disposed of entirely?*/
+		/* JACK cannot support seamless looping at present */
 		Config->set_seamless_loop (false);
+	} else {
+		/* reset to whatever the value was before we last switched slaves */
+		Config->set_seamless_loop (_was_seamless);
 	}
 
+	/* save value of seamless from before the switch */
+	_was_seamless = seamless;
+
 	ev->slave = src;
 	queue_event (ev);
 }
@@ -89,9 +117,9 @@ Session::request_diskstream_speed (Diskstream& ds, double speed)
 }
 
 void
-Session::request_stop (bool abort)
+Session::request_stop (bool abort, bool clear_state)
 {
-	Event* ev = new Event (Event::SetTransportSpeed, Event::Add, Event::Immediate, 0, 0.0, abort);
+	Event* ev = new Event (Event::SetTransportSpeed, Event::Add, Event::Immediate, 0, 0.0, abort, clear_state);
 	queue_event (ev);
 }
 
@@ -103,7 +131,7 @@ Session::request_locate (nframes_t target_frame, bool with_roll)
 }
 
 void
-Session::force_locate (nframes_t target_frame, bool with_roll)
+Session::force_locate (nframes64_t target_frame, bool with_roll)
 {
 	Event *ev = new Event (with_roll ? Event::LocateRoll : Event::Locate, Event::Add, Event::Immediate, target_frame, 0, true);
 	queue_event (ev);
@@ -132,8 +160,22 @@ Session::request_play_loop (bool yn, bool leave_rolling)
 }
 
 void
-Session::realtime_stop (bool abort)
+Session::request_play_range (list<AudioRange>* range, bool leave_rolling)
+{
+	Event* ev = new Event (Event::SetPlayAudioRange, Event::Add, Event::Immediate, 0, (leave_rolling ? 1.0 : 0.0));
+	if (range) {
+		ev->audio_range = *range;
+	} else {
+		ev->audio_range.clear ();
+	}
+	queue_event (ev);
+}
+
+void
+Session::realtime_stop (bool abort, bool clear_state)
 {
+	PostTransportWork todo = PostTransportWork (0);
+
 	/* assume that when we start, we'll be moving forwards */
 
 	// FIXME: where should this really be? [DR]
@@ -142,9 +184,9 @@ Session::realtime_stop (bool abort)
 	deliver_mmc (MIDI::MachineControl::cmdLocate, _transport_frame);
 
 	if (_transport_speed < 0.0f) {
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportStop | PostTransportReverse);
+		todo = (PostTransportWork (todo | PostTransportStop | PostTransportReverse));
 	} else {
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportStop);
+		todo = PostTransportWork (todo | PostTransportStop);
 	}
 
 	if (actively_recording()) {
@@ -158,11 +200,19 @@ Session::realtime_stop (bool abort)
 
 		/* the duration change is not guaranteed to have happened, but is likely */
 
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportDuration);
+		todo = PostTransportWork (todo | PostTransportDuration);
 	}
 
 	if (abort) {
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportAbort);
+		todo = PostTransportWork (todo | PostTransportAbort);
+	}
+
+	if (clear_state) {
+		todo = PostTransportWork (todo | PostTransportClearSubstate);
+	}
+
+	if (todo) {
+		add_post_transport_work (todo);
 	}
 
 	_clear_event_type (Event::StopOnce);
@@ -188,29 +238,30 @@ Session::butler_transport_work ()
 {
   restart:
 	bool finished;
+	PostTransportWork ptw;
 	boost::shared_ptr<RouteList> r = routes.reader ();
 	boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 
 	int on_entry = g_atomic_int_get (&_butler->should_do_transport_work);
 	finished = true;
-
-	if (post_transport_work & PostTransportCurveRealloc) {
+	ptw = post_transport_work();
+	if (ptw & PostTransportCurveRealloc) {
 		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 			(*i)->curve_reallocate();
 		}
 	}
 
-	if (post_transport_work & PostTransportInputChange) {
+	if (ptw & PostTransportInputChange) {
 		for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 			(*i)->non_realtime_input_change ();
 		}
 	}
 
-	if (post_transport_work & PostTransportSpeed) {
+	if (ptw & PostTransportSpeed) {
 		non_realtime_set_speed ();
 	}
 
-	if (post_transport_work & PostTransportReverse) {
+	if (ptw & PostTransportReverse) {
 
 		clear_clicks();
 		cumulative_rf_motion = 0;
@@ -218,7 +269,7 @@ Session::butler_transport_work ()
 
 		/* don't seek if locate will take care of that in non_realtime_stop() */
 
-		if (!(post_transport_work & PostTransportLocate)) {
+		if (!(ptw & PostTransportLocate)) {
 
 			for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 				if (!(*i)->hidden()) {
@@ -233,19 +284,19 @@ Session::butler_transport_work ()
 		}
 	}
 
-	if (post_transport_work & PostTransportLocate) {
+	if (ptw & PostTransportLocate) {
 		non_realtime_locate ();
 	}
 
-	if (post_transport_work & PostTransportStop) {
-		non_realtime_stop (post_transport_work & PostTransportAbort, on_entry, finished);
+	if (ptw & PostTransportStop) {
+		non_realtime_stop (ptw & PostTransportAbort, on_entry, finished);
 		if (!finished) {
 			g_atomic_int_dec_and_test (&_butler->should_do_transport_work);
 			goto restart;
 		}
 	}
 
-	if (post_transport_work & PostTransportOverWrite) {
+	if (ptw & PostTransportOverWrite) {
 		non_realtime_overwrite (on_entry, finished);
 		if (!finished) {
 			g_atomic_int_dec_and_test (&_butler->should_do_transport_work);
@@ -253,7 +304,7 @@ Session::butler_transport_work ()
 		}
 	}
 
-	if (post_transport_work & PostTransportAudition) {
+	if (ptw & PostTransportAudition) {
 		non_realtime_set_audition ();
 	}
 
@@ -305,6 +356,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 	time_t     xnow;
 	bool       did_record;
 	bool       saved;
+	PostTransportWork ptw = post_transport_work();
 
 	did_record = false;
 	saved = false;
@@ -390,7 +442,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 		(Config->get_slave_source() == None && config.get_auto_return());
 
 	if (auto_return_enabled ||
-	    (post_transport_work & PostTransportLocate) ||
+	    (ptw & PostTransportLocate) ||
 	    (_requested_return_frame >= 0) ||
 	    synced_to_jack()) {
 
@@ -399,7 +451,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 		}
 
 		if ((auto_return_enabled || synced_to_jack() || _requested_return_frame >= 0) &&
-		    !(post_transport_work & PostTransportLocate)) {
+		    !(ptw & PostTransportLocate)) {
 
 	/* no explicit locate queued */
 
@@ -461,6 +513,14 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 
 	}
 
+	/* do this before seeking, because otherwise the Diskstreams will do the wrong thing in seamless loop mode.
+	*/
+
+	if (ptw & PostTransportClearSubstate) {
+		_play_range = false;
+		unset_play_loop ();
+	}
+
 	/* this for() block can be put inside the previous if() and has the effect of ... ??? what */
 
 
@@ -481,24 +541,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 	deliver_mmc (MIDI::MachineControl::cmdStop, 0);
 	deliver_mmc (MIDI::MachineControl::cmdLocate, _transport_frame);
 
-	if (did_record) {
-
-		/* XXX its a little odd that we're doing this here
-		   when realtime_stop(), which has already executed,
-		   will have done this.
-		   JLC - so let's not because it seems unnecessary and breaks loop record
-		*/
-#if 0
-		if (!Config->get_latched_record_enable()) {
-			g_atomic_int_set (&_record_status, Disabled);
-		} else {
-			g_atomic_int_set (&_record_status, Enabled);
-		}
-		RecordStateChanged (); /* emit signal */
-#endif
-	}
-
-	if ((post_transport_work & PostTransportLocate) && get_record_enabled()) {
+	if ((ptw & PostTransportLocate) && get_record_enabled()) {
 		/* capture start has been changed, so save pending state */
 		save_state ("", true);
 		saved = true;
@@ -514,23 +557,21 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 		save_state (_current_snapshot_name);
 	}
 
-	if (post_transport_work & PostTransportDuration) {
+	if (ptw & PostTransportDuration) {
 		DurationChanged (); /* EMIT SIGNAL */
 	}
 
-	if (post_transport_work & PostTransportStop) {
+	if (ptw & PostTransportStop) {
 		_play_range = false;
 		play_loop = false;
 	}
 
-        nframes_t tf = _transport_frame;
-
-        PositionChanged (tf); /* EMIT SIGNAL */
+        PositionChanged ((nframes64_t) _transport_frame); /* EMIT SIGNAL */
 	TransportStateChange (); /* EMIT SIGNAL */
 
 	/* and start it up again if relevant */
 
-	if ((post_transport_work & PostTransportLocate) && Config->get_slave_source() == None && pending_locate_roll) {
+	if ((ptw & PostTransportLocate) && Config->get_slave_source() == None && pending_locate_roll) {
 		request_transport_speed (1.0);
 		pending_locate_roll = false;
 	}
@@ -561,35 +602,48 @@ Session::check_declick_out ()
 }
 
 void
-Session::set_play_loop (bool yn, bool leave_rolling)
+Session::unset_play_loop ()
+{
+	play_loop = false;
+	clear_events (Event::AutoLoop);
+	
+	// set all diskstreams to NOT use internal looping
+	boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
+	for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
+		if (!(*i)->hidden()) {
+			(*i)->set_loop (0);
+		}
+	}
+}
+
+void
+Session::set_play_loop (bool yn)
 {
 	/* Called from event-handling context */
 
 	Location *loc;
 
-	if (yn == play_loop) {
-		return;
-	}
-
-	if ((actively_recording() && yn) || (loc = _locations.auto_loop_location()) == 0) {
+	if (yn == play_loop || (actively_recording() && yn) || (loc = _locations.auto_loop_location()) == 0) {
+		/* nothing to do, or can't change loop status while recording */
 		return;
 	}
-
+	
 	set_dirty();
-
+	
 	if (yn && Config->get_seamless_loop() && synced_to_jack()) {
 		warning << _("Seamless looping cannot be supported while Ardour is using JACK transport.\n"
 			     "Recommend changing the configured options")
 			<< endmsg;
 		return;
 	}
+	
+	if (yn) {
 
-
-	if ((play_loop = yn)) {
+		play_loop = true;
 
 		if (loc) {
 
-			set_play_range (false, true);
+			unset_play_range ();
 
 			if (Config->get_seamless_loop()) {
 				// set all diskstreams to use internal looping
@@ -609,34 +663,26 @@ Session::set_play_loop (bool yn, bool leave_rolling)
 					}
 				}
 			}
-
-			/* stick in the loop event */
-
+			
+			/* put the loop event into the event list */
+			
 			Event* event = new Event (Event::AutoLoop, Event::Replace, loc->end(), loc->start(), 0.0f);
 			merge_event (event);
 
-			
-			// locate to start of loop and roll
-			event = new Event (Event::LocateRoll, Event::Add, Event::Immediate, loc->start(), 0, !synced_to_jack());
-			merge_event (event);
-		}
+			/* locate to start of loop and roll. If doing seamless loop, force a 
+			   locate+buffer refill even if we are positioned there already.
+			*/
 
+			start_locate (loc->start(), true, true, false, Config->get_seamless_loop());
+		}
 
 	} else {
-		clear_events (Event::AutoLoop);
-
-		// set all diskstreams to NOT use internal looping
-		boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
-		for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
-			if (!(*i)->hidden()) {
-				(*i)->set_loop (0);
-			}
-		}
 
+		unset_play_loop ();
 	}
-	TransportStateChange (); /* EMIT SIGNAL */
-}
 
+	TransportStateChange ();
+}
 void
 Session::flush_all_inserts ()
 {
@@ -648,12 +694,12 @@ Session::flush_all_inserts ()
 }
 
 void
-Session::start_locate (nframes_t target_frame, bool with_roll, bool with_flush, bool with_loop)
+Session::start_locate (nframes64_t target_frame, bool with_roll, bool with_flush, bool with_loop, bool force)
 {
 	if (synced_to_jack()) {
 
 		double sp;
-		nframes_t pos;
+		nframes64_t pos;
 
 		_slave->speed_and_position (sp, pos);
 
@@ -672,7 +718,7 @@ Session::start_locate (nframes_t target_frame, bool with_roll, bool with_flush,
 		}
 
 	} else {
-		locate (target_frame, with_roll, with_flush, with_loop);
+		locate (target_frame, with_roll, with_flush, with_loop, force);
 	}
 }
 
@@ -696,13 +742,13 @@ Session::micro_locate (nframes_t distance)
 }
 
 void
-Session::locate (nframes_t target_frame, bool with_roll, bool with_flush, bool with_loop)
+Session::locate (nframes64_t target_frame, bool with_roll, bool with_flush, bool with_loop, bool force)
 {
 	if (actively_recording() && !with_loop) {
 		return;
 	}
 
-	if (_transport_frame == target_frame && !loop_changing && !with_loop) {
+	if (!force && _transport_frame == target_frame && !loop_changing && !with_loop) {
 		if (with_roll) {
 			set_transport_speed (1.0, false);
 		}
@@ -730,17 +776,18 @@ Session::locate (nframes_t target_frame, bool with_roll, bool with_flush, bool w
 	}
 
 	if (transport_rolling() && (!auto_play_legal || !config.get_auto_play()) && !with_roll && !(synced_to_jack() && play_loop)) {
-		realtime_stop (false);
+		realtime_stop (false, true); // XXX paul - check if the 2nd arg is really correct
 	}
 
-	if ( !with_loop || loop_changing) {
+	if (force || !with_loop || loop_changing) {
 
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportLocate);
+		PostTransportWork todo = PostTransportLocate;
 
 		if (with_roll) {
-			post_transport_work = PostTransportWork (post_transport_work | PostTransportRoll);
-		}
+			todo = PostTransportWork (todo | PostTransportRoll);
+		} 
 
+		add_post_transport_work (todo);
 		_butler->schedule_transport_work ();
 
 	} else {
@@ -792,7 +839,7 @@ Session::locate (nframes_t target_frame, bool with_roll, bool with_flush, bool w
 
 		if (al && (_transport_frame < al->start() || _transport_frame > al->end())) {
 			// cancel looping directly, this is called from event handling context
-			set_play_loop (false, false);
+			set_play_loop (false);
 		}
 		else if (al && _transport_frame == al->start()) {
 			if (with_loop) {
@@ -824,7 +871,7 @@ Session::locate (nframes_t target_frame, bool with_roll, bool with_flush, bool w
  * @param abort
  */
 void
-Session::set_transport_speed (double speed, bool abort)
+Session::set_transport_speed (double speed, bool abort, bool clear_state)
 {
 	if (_transport_speed == speed) {
 		return;
@@ -859,6 +906,13 @@ Session::set_transport_speed (double speed, bool abort)
 		}
 
 		if (synced_to_jack ()) {
+			if (clear_state) {
+				/* do this here because our response to the slave won't 
+				   take care of it.
+				*/
+				_play_range = false;
+				unset_play_loop ();
+			}
 			_engine.transport_stop ();
 		} else {
 			stop_transport (abort);
@@ -919,9 +973,11 @@ Session::set_transport_speed (double speed, bool abort)
 		/* if we are reversing relative to the current speed, or relative to the speed
 		   before the last stop, then we have to do extra work.
 		*/
+		
+		PostTransportWork todo = PostTransportWork (0);
 
 		if ((_transport_speed && speed * _transport_speed < 0.0) || (_last_transport_speed * speed < 0.0) || (_last_transport_speed == 0.0f && speed < 0.0f)) {
-			post_transport_work = PostTransportWork (post_transport_work | PostTransportReverse);
+			todo = PostTransportWork (todo | PostTransportReverse);
 		}
 
 		_last_transport_speed = _transport_speed;
@@ -930,11 +986,13 @@ Session::set_transport_speed (double speed, bool abort)
 		boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 		for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 			if ((*i)->realtime_set_speed ((*i)->speed(), true)) {
-				post_transport_work = PostTransportWork (post_transport_work | PostTransportSpeed);
+				todo = PostTransportWork (todo | PostTransportSpeed);
+				break;
 			}
 		}
 
-		if (post_transport_work & (PostTransportSpeed|PostTransportReverse)) {
+		if (todo) {
+			add_post_transport_work (todo);
 			_butler->schedule_transport_work ();
 		}
 	}
@@ -943,7 +1001,7 @@ Session::set_transport_speed (double speed, bool abort)
 
 /** Stop the transport.  */
 void
-Session::stop_transport (bool abort)
+Session::stop_transport (bool abort, bool clear_state)
 {
 	if (_transport_speed == 0.0f) {
 		return;
@@ -979,7 +1037,7 @@ Session::stop_transport (bool abort)
 		return;
 	}
 
-	realtime_stop (abort);
+	realtime_stop (abort, clear_state);
 	_butler->schedule_transport_work ();
 }
 
@@ -1031,7 +1089,9 @@ Session::start_transport ()
 void
 Session::post_transport ()
 {
-	if (post_transport_work & PostTransportAudition) {
+	PostTransportWork ptw = post_transport_work ();
+
+	if (ptw & PostTransportAudition) {
 		if (auditioner && auditioner->active()) {
 			process_function = &Session::process_audition;
 		} else {
@@ -1039,14 +1099,14 @@ Session::post_transport ()
 		}
 	}
 
-	if (post_transport_work & PostTransportStop) {
+	if (ptw & PostTransportStop) {
 
 		transport_sub_state = 0;
 	}
 
-	if (post_transport_work & PostTransportLocate) {
+	if (ptw & PostTransportLocate) {
 
-		if (((Config->get_slave_source() == None && (auto_play_legal && config.get_auto_play())) && !_exporting) || (post_transport_work & PostTransportRoll)) {
+		if (((Config->get_slave_source() == None && (auto_play_legal && config.get_auto_play())) && !_exporting) || (ptw & PostTransportRoll)) {
 			start_transport ();
 
 		} else {
@@ -1055,8 +1115,10 @@ Session::post_transport ()
 	}
 
 	set_next_event ();
-
-	post_transport_work = PostTransportWork (0);
+	/* XXX is this really safe? shouldn't we just be unsetting the bits that we actually
+	   know were handled ?
+	*/
+	set_post_transport_work (PostTransportWork (0));
 }
 
 void
@@ -1161,7 +1223,7 @@ Session::set_slave_source (SlaveSource src)
 	}
 
 	if (non_rt_required) {
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportSpeed);
+		add_post_transport_work (PostTransportSpeed);
 		_butler->schedule_transport_work ();
 	}
 
@@ -1171,7 +1233,7 @@ Session::set_slave_source (SlaveSource src)
 void
 Session::reverse_diskstream_buffers ()
 {
-	post_transport_work = PostTransportWork (post_transport_work | PostTransportReverse);
+	add_post_transport_work (PostTransportReverse);
 	_butler->schedule_transport_work ();
 }
 
@@ -1179,124 +1241,113 @@ void
 Session::set_diskstream_speed (Diskstream* stream, double speed)
 {
 	if (stream->realtime_set_speed (speed, false)) {
-		post_transport_work = PostTransportWork (post_transport_work | PostTransportSpeed);
+		add_post_transport_work (PostTransportSpeed);
 		_butler->schedule_transport_work ();
 		set_dirty ();
 	}
 }
 
 void
-Session::set_audio_range (list<AudioRange>& range)
-{
-	Event *ev = new Event (Event::SetAudioRange, Event::Add, Event::Immediate, 0, 0.0f);
-	ev->audio_range = range;
-	queue_event (ev);
-}
-
-void
-Session::request_play_range (bool yn, bool leave_rolling)
-{
-	Event* ev = new Event (Event::SetPlayRange, Event::Add, Event::Immediate, 0, (leave_rolling ? 1.0f : 0.0f), yn);
-	queue_event (ev);
-}
-
-void
-Session::set_play_range (bool yn, bool leave_rolling)
+Session::unset_play_range ()
 {
-	/* Called from event-processing context */
-
-	if (yn) {
-		/* cancel loop play */
-		set_play_range (false, true);
-	}
-
-	_play_range = yn;
-	setup_auto_play ();
-
-
-	if (!_play_range && !leave_rolling) {
-		/* stop transport */
-		Event* ev = new Event (Event::SetTransportSpeed, Event::Add, Event::Immediate, 0, 0.0f, false);
-		merge_event (ev);
-	}
-	TransportStateChange (); /* EMIT SIGNAL */
+	_play_range = false;
+	_clear_event_type (Event::RangeStop);
+	_clear_event_type (Event::RangeLocate);
 }
 
 void
-Session::setup_auto_play ()
+Session::set_play_range (list<AudioRange>& range, bool leave_rolling)
 {
-	/* Called from event-processing context */
-
 	Event* ev;
 
-	_clear_event_type (Event::RangeStop);
-	_clear_event_type (Event::RangeLocate);
+	/* Called from event-processing context */
 
-	if (!_play_range) {
+	unset_play_range ();
+	
+	if (range.empty()) {
+		/* _play_range set to false in unset_play_range()
+		 */
+		if (!leave_rolling) {
+			/* stop transport */
+			Event* ev = new Event (Event::SetTransportSpeed, Event::Add, Event::Immediate, 0, 0.0f, false);
+			merge_event (ev);
+		}
 		return;
 	}
 
-	list<AudioRange>::size_type sz = current_audio_range.size();
+	_play_range = true;
 
-	if (sz > 1) {
+	/* cancel loop play */
+	unset_play_loop ();
 
-		list<AudioRange>::iterator i = current_audio_range.begin();
+	list<AudioRange>::size_type sz = range.size();
+	
+	if (sz > 1) {
+		
+		list<AudioRange>::iterator i = range.begin(); 
 		list<AudioRange>::iterator next;
-
-		while (i != current_audio_range.end()) {
-
+		
+		while (i != range.end()) {
+			
 			next = i;
 			++next;
-
+			
 			/* locating/stopping is subject to delays for declicking.
 			 */
-
+			
 			nframes_t requested_frame = (*i).end;
-
+			
 			if (requested_frame > current_block_size) {
 				requested_frame -= current_block_size;
 			} else {
 				requested_frame = 0;
 			}
-
-			if (next == current_audio_range.end()) {
+			
+			if (next == range.end()) {
 				ev = new Event (Event::RangeStop, Event::Add, requested_frame, 0, 0.0f);
 			} else {
 				ev = new Event (Event::RangeLocate, Event::Add, requested_frame, (*next).start, 0.0f);
 			}
-
+			
 			merge_event (ev);
-
+			
 			i = next;
 		}
-
+		
 	} else if (sz == 1) {
 
-		ev = new Event (Event::RangeStop, Event::Add, current_audio_range.front().end, 0, 0.0f);
+		ev = new Event (Event::RangeStop, Event::Add, range.front().end, 0, 0.0f);
 		merge_event (ev);
+		
+	} 
 
-	}
+	/* save range so we can do auto-return etc. */
+
+	current_audio_range = range;
 
 	/* now start rolling at the right place */
 
-	ev = new Event (Event::LocateRoll, Event::Add, Event::Immediate, current_audio_range.front().start, 0.0f, false);
+	ev = new Event (Event::LocateRoll, Event::Add, Event::Immediate, range.front().start, 0.0f, false);
 	merge_event (ev);
+	
+	TransportStateChange ();
 }
 
 void
-Session::request_roll_at_and_return (nframes_t start, nframes_t return_to)
+Session::request_bounded_roll (nframes_t start, nframes_t end)
 {
-	Event *ev = new Event (Event::LocateRollLocate, Event::Add, Event::Immediate, return_to, 1.0);
-	ev->target2_frame = start;
-	queue_event (ev);
-}
+	AudioRange ar (start, end, 0);
+	list<AudioRange> lar;
 
+	lar.push_back (ar);
+	request_play_range (&lar, true);
+}
 void
-Session::request_bounded_roll (nframes_t start, nframes_t end)
+Session::request_roll_at_and_return (nframes_t start, nframes_t return_to)
 {
-	Event *ev = new Event (Event::StopOnce, Event::Replace, end, Event::Immediate, 0.0);
+	Event *ev = new Event (Event::LocateRollLocate, Event::Add, Event::Immediate, return_to, 1.0);
+	ev->target2_frame = start;
 	queue_event (ev);
-	request_locate (start, true);
 }
 
 void
@@ -1312,10 +1363,10 @@ Session::engine_halted ()
 	*/
 
 	g_atomic_int_set (&_butler->should_do_transport_work, 0);
-	post_transport_work = PostTransportWork (0);
+	set_post_transport_work (PostTransportWork (0));
 	_butler->stop ();
 
-	realtime_stop (false);
+	realtime_stop (false, true);
 	non_realtime_stop (false, 0, ignored);
 	transport_sub_state = 0;
 
@@ -1326,7 +1377,7 @@ Session::engine_halted ()
 void
 Session::xrun_recovery ()
 {
-	Xrun (transport_frame()); //EMIT SIGNAL
+	Xrun ((nframes64_t)_transport_frame); //EMIT SIGNAL
 
 	if (Config->get_stop_recording_on_xrun() && actively_recording()) {
 
@@ -1342,12 +1393,14 @@ void
 Session::update_latency_compensation (bool with_stop, bool abort)
 {
 	bool update_jack = false;
+	PostTransportWork ptw;
 
 	if (_state_of_the_state & Deletion) {
 		return;
 	}
 
 	_worst_track_latency = 0;
+	ptw = post_transport_work();
 
 #undef DEBUG_LATENCY
 #ifdef DEBUG_LATENCY
@@ -1359,8 +1412,7 @@ Session::update_latency_compensation (bool with_stop, bool abort)
 	for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 
 		if (with_stop) {
-			(*i)->handle_transport_stopped (abort, (post_transport_work & PostTransportLocate),
-							(!(post_transport_work & PostTransportLocate) || pending_locate_flush));
+			(*i)->handle_transport_stopped (abort, (ptw & PostTransportLocate), (!(ptw & PostTransportLocate) || pending_locate_flush));
 		}
 
 		nframes_t old_latency = (*i)->output()->signal_latency ();
diff --git a/libs/ardour/slave.cc b/libs/ardour/slave.cc
index f07ea4c872..be88fe223c 100644
--- a/libs/ardour/slave.cc
+++ b/libs/ardour/slave.cc
@@ -35,13 +35,13 @@ SlaveSessionProxy::frame_rate() const
 	return session.frame_rate();
 }
 
-nframes_t
+nframes64_t
 SlaveSessionProxy::audible_frame() const
 {
 	return session.audible_frame();
 }
 
-nframes_t
+nframes64_t
 SlaveSessionProxy::transport_frame() const
 {
 	return session.transport_frame();
@@ -53,14 +53,14 @@ SlaveSessionProxy::frames_since_cycle_start() const
 	return session.engine().frames_since_cycle_start();
 }
 
-nframes_t
+nframes64_t
 SlaveSessionProxy::frame_time() const
 {
 	return session.engine().frame_time();
 }
 
 void
-SlaveSessionProxy::request_locate(nframes_t frame, bool with_roll)
+SlaveSessionProxy::request_locate(nframes64_t frame, bool with_roll)
 {
 	session.request_locate(frame, with_roll);
 }