From 4cc6372dc3efe86cb919d62d805590c9155a3c14 Mon Sep 17 00:00:00 2001
From: Gon Solo <gonsolo@gmail.com>
Date: Sat, 25 Feb 2023 23:18:40 +0100
Subject: [PATCH] Revert "require use of BBT_Argument as both parameter and
 return type from most methods (libs edition)"

This reverts commit 259499fc5f9a349a9c729947813bdb5231fbdaa9.
---
 libs/ardour/ardour/triggerbox.h               |  6 +-
 libs/ardour/luabindings.cc                    |  4 +-
 libs/ardour/session_time.cc                   |  2 +-
 libs/ardour/session_transport.cc              |  4 +-
 libs/ardour/session_vst.cc                    |  4 +-
 libs/ardour/triggerbox.cc                     | 36 +++++------
 .../control_protocol/basic_ui.cc              |  2 +-
 libs/temporal/tempo.cc                        | 63 +++++--------------
 libs/temporal/temporal/bbt_argument.h         |  2 +-
 libs/temporal/temporal/tempo.h                | 24 ++++---
 libs/temporal/timeline.cc                     |  6 +-
 11 files changed, 57 insertions(+), 96 deletions(-)

diff --git a/libs/ardour/ardour/triggerbox.h b/libs/ardour/ardour/triggerbox.h
index 95981c339d..052c8cbb0e 100644
--- a/libs/ardour/ardour/triggerbox.h
+++ b/libs/ardour/ardour/triggerbox.h
@@ -292,7 +292,7 @@ class LIBARDOUR_API Trigger : public PBD::Stateful {
 	timepos_t current_pos() const;
 	double position_as_fraction() const;
 
-	Temporal::BBT_Argument compute_start (Temporal::TempoMap::SharedPtr const &, samplepos_t start, samplepos_t end, Temporal::BBT_Offset const & q, samplepos_t& start_samples, bool& will_start);
+	Temporal::BBT_Time compute_start (Temporal::TempoMap::SharedPtr const &, samplepos_t start, samplepos_t end, Temporal::BBT_Offset const & q, samplepos_t& start_samples, bool& will_start);
 	virtual timepos_t compute_end (Temporal::TempoMap::SharedPtr const &, Temporal::BBT_Time const &, samplepos_t, Temporal::Beats &) = 0;
 	virtual void start_and_roll_to (samplepos_t start, samplepos_t position, uint32_t cnt) = 0;
 
@@ -337,11 +337,11 @@ class LIBARDOUR_API Trigger : public PBD::Stateful {
 
 
 	bool compute_quantized_transition (samplepos_t start_sample, Temporal::Beats const & start, Temporal::Beats const & end,
-	                                   Temporal::BBT_Argument& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
+	                                   Temporal::BBT_Time& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
 	                                   Temporal::TempoMap::SharedPtr const & tmap, Temporal::BBT_Offset const & q);
 
 	pframes_t compute_next_transition (samplepos_t start_sample, Temporal::Beats const & start, Temporal::Beats const & end, pframes_t nframes,
-	                                   Temporal::BBT_Argument& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
+	                                   Temporal::BBT_Time& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
 	                                   Temporal::TempoMap::SharedPtr const & tmap);
 
 
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 2d18248eb7..514cd6c053 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -799,8 +799,8 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("meter_at_bbt", (Temporal::MeterPoint const& (Temporal::TempoMap::*)(Temporal::BBT_Argument const &) const) &Temporal::TempoMap::meter_at)
 		.addFunction ("meter_at_beats", (Temporal::MeterPoint const& (Temporal::TempoMap::*)(Temporal::Beats const &) const) &Temporal::TempoMap::meter_at)
 
-		.addFunction ("bbt_at", (Temporal::BBT_Argument (Temporal::TempoMap::*)(Temporal::timepos_t const &) const) &Temporal::TempoMap::bbt_at)
-		.addFunction ("bbt_at_beats", (Temporal::BBT_Argument (Temporal::TempoMap::*)(Temporal::Beats const &) const) &Temporal::TempoMap::bbt_at)
+		.addFunction ("bbt_at", (Temporal::BBT_Time (Temporal::TempoMap::*)(Temporal::timepos_t const &) const) &Temporal::TempoMap::bbt_at)
+		.addFunction ("bbt_at_beats", (Temporal::BBT_Time (Temporal::TempoMap::*)(Temporal::Beats const &) const) &Temporal::TempoMap::bbt_at)
 
 #ifdef WITH_SUPERCLOCK_BINDINGS
 		.addFunction ("tempo_at_sc", (Temporal::TempoPoint const& (Temporal::TempoMap::*)(superclock_t) const) &Temporal::TempoMap::tempo_at)
diff --git a/libs/ardour/session_time.cc b/libs/ardour/session_time.cc
index 3501bb6b84..8be19459f0 100644
--- a/libs/ardour/session_time.cc
+++ b/libs/ardour/session_time.cc
@@ -234,7 +234,7 @@ Session::convert_to_samples (AnyTime const & position)
 
 	switch (position.type) {
 	case AnyTime::BBT:
-		return Temporal::superclock_to_samples (TempoMap::use()->superclock_at (BBT_Argument (timepos_t::zero (Temporal::BeatTime), position.bbt)), _current_sample_rate);
+		return Temporal::superclock_to_samples (TempoMap::use()->superclock_at (position.bbt), _current_sample_rate);
 		break;
 
 	case AnyTime::Timecode:
diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc
index 502e4fa339..2e9713f226 100644
--- a/libs/ardour/session_transport.cc
+++ b/libs/ardour/session_transport.cc
@@ -2120,8 +2120,8 @@ Session::flush_cue_recording ()
 	_locations->clear_cue_markers (_last_roll_location, _transport_sample);
 
 	while (TriggerBox::cue_records.read (&cr, 1) == 1) {
-		BBT_Argument bbt = tmap->bbt_at (timepos_t (cr.when));
-		bbt = BBT_Argument (bbt.reference(), bbt.round_up_to_bar ());
+		BBT_Time bbt = tmap->bbt_at (timepos_t (cr.when));
+		bbt = bbt.round_up_to_bar ();
 
 		const timepos_t when (tmap->quarters_at (bbt));
 
diff --git a/libs/ardour/session_vst.cc b/libs/ardour/session_vst.cc
index ea1b0a2288..697a1e3b8c 100644
--- a/libs/ardour/session_vst.cc
+++ b/libs/ardour/session_vst.cc
@@ -200,14 +200,14 @@ intptr_t Session::vst_callback (
 				newflags |= (kVstTimeSigValid);
 			}
 			if ((value & (kVstPpqPosValid)) || (value & (kVstBarsValid))) {
-				Temporal::BBT_Argument bbt;
+				Temporal::BBT_Time bbt;
 
 				try {
 					bbt = tmap->bbt_at (timepos_t (now));
 					bbt.beats = 1;
 					bbt.ticks = 0;
 					/* exact quarter note */
-					double ppqBar = DoubleableBeats (tmap->quarters_at (BBT_Argument (bbt))).to_double ();
+					double ppqBar = DoubleableBeats (tmap->quarters_at (bbt)).to_double ();
 					/* quarter note at sample position (not rounded to note subdivision) */
 					double ppqPos = DoubleableBeats (tmap->quarters_at_sample (now)).to_double();
 					if (value & (kVstPpqPosValid)) {
diff --git a/libs/ardour/triggerbox.cc b/libs/ardour/triggerbox.cc
index f13d4575c7..73d1bfedb9 100644
--- a/libs/ardour/triggerbox.cc
+++ b/libs/ardour/triggerbox.cc
@@ -929,18 +929,18 @@ Trigger::process_state_requests (BufferSet& bufs, pframes_t dest_offset)
 	}
 }
 
-Temporal::BBT_Argument
+Temporal::BBT_Time
 Trigger::compute_start (Temporal::TempoMap::SharedPtr const & tmap, samplepos_t start, samplepos_t end, Temporal::BBT_Offset const & q, samplepos_t& start_samples, bool& will_start)
 {
 	Temporal::Beats start_beats (tmap->quarters_at (timepos_t (start)));
 	Temporal::Beats end_beats (tmap->quarters_at (timepos_t (end)));
 
-	Temporal::BBT_Argument t_bbt;
+	Temporal::BBT_Time t_bbt;
 	Temporal::Beats t_beats;
 
 	if (!compute_quantized_transition (start, start_beats, end_beats, t_bbt, t_beats, start_samples, tmap, q)) {
 		will_start = false;
-		return Temporal::BBT_Argument ();
+		return Temporal::BBT_Time ();
 	}
 
 	will_start = true;
@@ -949,7 +949,7 @@ Trigger::compute_start (Temporal::TempoMap::SharedPtr const & tmap, samplepos_t
 
 bool
 Trigger::compute_quantized_transition (samplepos_t start_sample, Temporal::Beats const & start_beats, Temporal::Beats const & end_beats,
-                                       Temporal::BBT_Argument& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
+                                       Temporal::BBT_Time& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
                                        Temporal::TempoMap::SharedPtr const & tmap, Temporal::BBT_Offset const & q)
 {
 	/* XXX need to use global grid here is quantization == zero */
@@ -958,7 +958,7 @@ Trigger::compute_quantized_transition (samplepos_t start_sample, Temporal::Beats
 	 * quantization, the next time for a transition.
 	 */
 
-	Temporal::BBT_Argument possible_bbt;
+	Temporal::BBT_Time possible_bbt;
 	Temporal::Beats possible_beats;
 	samplepos_t possible_samples;
 
@@ -978,7 +978,7 @@ Trigger::compute_quantized_transition (samplepos_t start_sample, Temporal::Beats
 	} else {
 
 		possible_bbt = tmap->bbt_at (timepos_t (start_beats));
-		possible_bbt = Temporal::BBT_Argument (possible_bbt.reference(), possible_bbt.round_up_to_bar ());
+		possible_bbt = possible_bbt.round_up_to_bar ();
 		/* bars are 1-based; 'every 4 bars' means 'on bar 1, 5, 9, ...' */
 		possible_bbt.bars = 1 + ((possible_bbt.bars-1) / q.bars * q.bars);
 		possible_beats = tmap->quarters_at (possible_bbt);
@@ -1004,7 +1004,7 @@ Trigger::compute_quantized_transition (samplepos_t start_sample, Temporal::Beats
 
 pframes_t
 Trigger::compute_next_transition (samplepos_t start_sample, Temporal::Beats const & start, Temporal::Beats const & end, pframes_t nframes,
-                                  Temporal::BBT_Argument& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
+                                  Temporal::BBT_Time& t_bbt, Temporal::Beats& t_beats, samplepos_t& t_samples,
                                   Temporal::TempoMap::SharedPtr const & tmap)
 {
 	using namespace Temporal;
@@ -1072,7 +1072,7 @@ Trigger::maybe_compute_next_transition (samplepos_t start_sample, Temporal::Beat
 		return;
 	}
 
-	Temporal::BBT_Argument transition_bbt;
+	Temporal::BBT_Time transition_bbt;
 	TempoMap::SharedPtr tmap (TempoMap::use());
 
 	if (!compute_next_transition (start_sample, start, end, nframes, transition_bbt, transition_beats, transition_samples, tmap)) {
@@ -1449,15 +1449,13 @@ AudioTrigger::compute_end (Temporal::TempoMap::SharedPtr const & tmap, Temporal:
            _beatcnt : the expected duration of the trigger, based on analysis of its tempo .. can be overridden by the user later
 	*/
 
-	const Temporal::BBT_Argument transition_bba (timepos_t::zero (Temporal::BeatTime), transition_bbt);
-
-	samplepos_t end_by_follow_length = tmap->sample_at (tmap->bbt_walk (transition_bba, _follow_length));
+	samplepos_t end_by_follow_length = tmap->sample_at (tmap->bbt_walk(transition_bbt, _follow_length));
 	samplepos_t end_by_data_length = transition_sample + (data.length - _start_offset);
 	/* this could still blow up if the data is less than 1 tick long, but
 	   we should handle that elsewhere.
 	*/
 	const Temporal::Beats bc (Temporal::Beats::from_double (_beatcnt));
-	samplepos_t end_by_beatcnt = tmap->sample_at (tmap->bbt_walk (transition_bba, Temporal::BBT_Offset (0, bc.get_beats(), bc.get_ticks())));
+	samplepos_t end_by_beatcnt = tmap->sample_at (tmap->bbt_walk(transition_bbt, Temporal::BBT_Offset (0, bc.get_beats(), bc.get_ticks())));
 
 	DEBUG_TRACE (DEBUG::Triggers, string_compose ("%1 SO %9 @ %2 / %3 / %4 ends: FL %5 (from %6) BC %7 DL %8\n",
 	                                              index(), transition_sample, transition_beats, transition_bbt,
@@ -2317,10 +2315,8 @@ MIDITrigger::start_and_roll_to (samplepos_t start_pos, samplepos_t end_position,
 timepos_t
 MIDITrigger::compute_end (Temporal::TempoMap::SharedPtr const & tmap, Temporal::BBT_Time const & transition_bbt, samplepos_t, Temporal::Beats & effective_length)
 {
-	const Temporal::BBT_Argument transition_bba (timepos_t::zero(Temporal::BeatTime), transition_bbt);
-
-	Temporal::Beats end_by_follow_length = tmap->quarters_at (tmap->bbt_walk (transition_bba, _follow_length));
-	Temporal::Beats end_by_data_length = tmap->quarters_at (tmap->bbt_walk (transition_bba, Temporal::BBT_Offset (0, data_length.get_beats(), data_length.get_ticks())));
+	Temporal::Beats end_by_follow_length = tmap->quarters_at (tmap->bbt_walk (transition_bbt, _follow_length));
+	Temporal::Beats end_by_data_length = tmap->quarters_at (tmap->bbt_walk (transition_bbt, Temporal::BBT_Offset (0, data_length.get_beats(), data_length.get_ticks())));
 
 	DEBUG_TRACE (DEBUG::Triggers, string_compose ("%1 ends: TB %2 FL %3 EBFL %4 DL %5 EBDL %6 tbbt %7 fl %8\n",
 	                                              index(), transition_beats, _follow_length, end_by_follow_length, data_length, end_by_data_length, transition_bbt, _follow_length));
@@ -2330,10 +2326,10 @@ MIDITrigger::compute_end (Temporal::TempoMap::SharedPtr const & tmap, Temporal::
 
 		if (internal_use_follow_length()) {
 			final_beat = end_by_follow_length;
-			effective_length = tmap->bbtwalk_to_quarters (transition_bba, _follow_length);
+			effective_length = tmap->bbtwalk_to_quarters (transition_bbt, _follow_length);
 		} else {
 			final_beat = end_by_data_length;
-			effective_length = tmap->bbtwalk_to_quarters (transition_bba, Temporal::BBT_Offset (0, data_length.get_beats(), data_length.get_ticks()));
+			effective_length = tmap->bbtwalk_to_quarters (transition_bbt, Temporal::BBT_Offset (0, data_length.get_beats(), data_length.get_ticks()));
 		}
 
 	} else {
@@ -3196,7 +3192,7 @@ TriggerBox::fast_forward (CueEvents const & cues, samplepos_t transport_position
 	CueEvents::const_reverse_iterator c = cues.rbegin ();
 	samplepos_t pos = c->time;
 	TriggerPtr trig;
-	Temporal::BBT_Argument start_bbt;
+	Temporal::BBT_Time start_bbt;
 	samplepos_t start_samples;
 	Temporal::Beats effective_length;
 	bool will_start;
@@ -3348,7 +3344,7 @@ TriggerBox::fast_forward (CueEvents const & cues, samplepos_t transport_position
 
 	if (start_samples < transport_position) {
 		samplepos_t s = start_samples;
-		BBT_Argument ns = start_bbt;
+		BBT_Time ns = start_bbt;
 		const BBT_Offset step (0, effective_length.get_beats(), effective_length.get_ticks());
 
 		do {
diff --git a/libs/ctrl-interface/control_protocol/basic_ui.cc b/libs/ctrl-interface/control_protocol/basic_ui.cc
index d6b0fe027a..ddf47470e9 100644
--- a/libs/ctrl-interface/control_protocol/basic_ui.cc
+++ b/libs/ctrl-interface/control_protocol/basic_ui.cc
@@ -588,7 +588,7 @@ void
 BasicUI::jump_by_bars (int bars, LocateTransportDisposition ltd)
 {
 	TempoMap::SharedPtr tmap (TempoMap::fetch());
-	Temporal::BBT_Argument bbt (tmap->bbt_at (timepos_t (session->transport_sample())));
+	Temporal::BBT_Time bbt (tmap->bbt_at (timepos_t (session->transport_sample())));
 
 	bbt.bars += bars;
 	if (bbt.bars < 0) {
diff --git a/libs/temporal/tempo.cc b/libs/temporal/tempo.cc
index 996806d04d..65d33cbe64 100644
--- a/libs/temporal/tempo.cc
+++ b/libs/temporal/tempo.cc
@@ -636,36 +636,7 @@ MeterPoint::get_state () const
 	return base;
 }
 
-timepos_t
-TempoMetric::reftime() const
-{
-	return _tempo->map().reftime (*this);
-}
-
-timepos_t
-TempoMap::reftime (TempoMetric const &tm) const
-{
-	Points::const_iterator pi;
-
-	if (tm.meter().sclock() < tm.tempo().sclock()) {
-		pi = _points.s_iterator_to (*(static_cast<const Point*> (&tm.meter())));
-	} else {
-		pi = _points.s_iterator_to (*(static_cast<const Point*> (&tm.tempo())));
-	}
-
-	/* Walk backwards through points to find a BBT markers, or the start */
-
-	while (pi != _points.begin()) {
-		if (dynamic_cast<const MusicTimePoint*> (&*pi)) {
-			break;
-		}
-		--pi;
-	}
-
-	return timepos_t (pi->sclock());
-}
-
-Temporal::BBT_Argument
+Temporal::BBT_Time
 TempoMetric::bbt_at (timepos_t const & pos) const
 {
 	if (pos.is_beats()) {
@@ -704,9 +675,7 @@ TempoMetric::bbt_at (timepos_t const & pos) const
 
 	DEBUG_TRACE (DEBUG::TemporalMap, string_compose ("BBT offset from %3 @ %1: %2\n", (_tempo->beats() < _meter->beats() ?  _meter->bbt() : _tempo->bbt()), bbt_offset,
 	                                                 (_tempo->beats() < _meter->beats() ? "meter" : "tempo")));
-	timepos_t ref (std::min (_meter->sclock(), _tempo->sclock()));
-
-	return BBT_Argument (ref, _meter->bbt_add (reference_point->bbt(), bbt_offset));
+	return _meter->bbt_add (reference_point->bbt(), bbt_offset);
 }
 
 superclock_t
@@ -1696,7 +1665,7 @@ TempoMap::remove_meter (MeterPoint const & mp, bool with_reset)
 	}
 }
 
-Temporal::BBT_Argument
+Temporal::BBT_Time
 TempoMap::bbt_at (timepos_t const & pos) const
 {
 	if (pos.is_beats()) {
@@ -1705,20 +1674,16 @@ TempoMap::bbt_at (timepos_t const & pos) const
 	return bbt_at (pos.superclocks());
 }
 
-Temporal::BBT_Argument
+Temporal::BBT_Time
 TempoMap::bbt_at (superclock_t s) const
 {
-	TempoMetric metric (metric_at (s));
-	timepos_t ref (std::min (metric.tempo().sclock(), metric.meter().sclock()));
-	return BBT_Argument (ref, metric.bbt_at (timepos_t::from_superclock (s)));
+	return metric_at (s).bbt_at (timepos_t::from_superclock (s));
 }
 
-Temporal::BBT_Argument
+Temporal::BBT_Time
 TempoMap::bbt_at (Temporal::Beats const & qn) const
 {
-	TempoMetric metric (metric_at (qn));
-	timepos_t ref (std::min (metric.tempo().sclock(), metric.meter().sclock()));
-	return BBT_Argument (ref, metric.bbt_at (qn));
+	return metric_at (qn).bbt_at (qn);
 }
 
 #if 0
@@ -1976,7 +1941,7 @@ TempoMap::get_grid (TempoMapPoints& ret, superclock_t start, superclock_t end, u
 	TempoPoint const * tp = 0;
 	MeterPoint const * mp = 0;
 	Points::const_iterator p = _points.begin();
-	BBT_Argument bbt;
+	BBT_Time bbt;
 	Beats beats;
 
 	/* Find relevant meter for nominal start point */
@@ -2016,7 +1981,7 @@ TempoMap::get_grid (TempoMapPoints& ret, superclock_t start, superclock_t end, u
 		 * in effect at that time.
 		 */
 
-		const BBT_Argument new_bbt (metric.reftime(), metric.meter().round_up_to_beat (bbt));
+		const BBT_Time new_bbt = metric.meter().round_up_to_beat (bbt);
 
 		if (new_bbt != bbt) {
 
@@ -2068,7 +2033,8 @@ TempoMap::get_grid (TempoMapPoints& ret, superclock_t start, superclock_t end, u
 
 		if (bar != bbt) {
 
-			bbt = BBT_Argument (bbt.reference(), bar);
+			bbt = bar;
+
 
 			/* rebuild metric */
 
@@ -2369,7 +2335,7 @@ std::operator<<(std::ostream& str, TempoMapPoint const & tmp)
 	return str;
 }
 
-BBT_Argument
+BBT_Time
 TempoMap::bbt_walk (BBT_Argument const & bbt, BBT_Offset const & o) const
 {
 	BBT_Offset offset (o);
@@ -2383,7 +2349,7 @@ TempoMap::bbt_walk (BBT_Argument const & bbt, BBT_Offset const & o) const
 	/* trivial (and common) case: single tempo, single meter */
 
 	if (_tempos.size() == 1 && _meters.size() == 1) {
-		return BBT_Argument (_meters.front().bbt_add (bbt, o));
+		return _meters.front().bbt_add (bbt, o);
 	}
 
 	/* Find tempo,meter pair for bbt, and also for the next tempo and meter
@@ -2489,7 +2455,8 @@ TempoMap::bbt_walk (BBT_Argument const & bbt, BBT_Offset const & o) const
 		start.ticks %= ticks_per_beat;
 	}
 
-	return BBT_Argument (metric.reftime(), start);
+
+	return start;
 }
 
 Temporal::Beats
diff --git a/libs/temporal/temporal/bbt_argument.h b/libs/temporal/temporal/bbt_argument.h
index f6adeb4af9..8213f160f8 100644
--- a/libs/temporal/temporal/bbt_argument.h
+++ b/libs/temporal/temporal/bbt_argument.h
@@ -33,7 +33,7 @@ struct LIBTEMPORAL_API BBT_Argument : public BBT_Time
 	BBT_Argument (Temporal::timepos_t const & r) : BBT_Time (), _reference (r) {}
 	BBT_Argument (Temporal::timepos_t const & r, int32_t B, int32_t b, int32_t t) : BBT_Time (B, b, t), _reference (r) {}
 
-	explicit BBT_Argument (BBT_Time const & bbt) : BBT_Time (bbt),  _reference (Temporal::timepos_t (Temporal::BeatTime)) {}
+	/*explicit*/ BBT_Argument (BBT_Time const & bbt) : BBT_Time (bbt),  _reference (Temporal::timepos_t (Temporal::BeatTime)) {}
 	BBT_Argument (Temporal::timepos_t const & r, BBT_Time const & bbt) : BBT_Time (bbt),  _reference (r) {}
 
 	Temporal::timepos_t reference() const { return _reference; }
diff --git a/libs/temporal/temporal/tempo.h b/libs/temporal/temporal/tempo.h
index 3545839dea..dde1ac45dd 100644
--- a/libs/temporal/temporal/tempo.h
+++ b/libs/temporal/temporal/tempo.h
@@ -471,8 +471,6 @@ class LIBTEMPORAL_API TempoMetric
 	TempoMetric (TempoPoint const & t, MeterPoint const & m) : _tempo (&t), _meter (&m) {}
 	virtual ~TempoMetric () {}
 
-	timepos_t reftime() const;
-
 	TempoPoint const & tempo() const { return *_tempo; }
 	MeterPoint const & meter() const { return *_meter; }
 
@@ -486,7 +484,7 @@ class LIBTEMPORAL_API TempoMetric
 	superclock_t superclock_at (Beats const & qn) const { return _tempo->superclock_at (qn); }
 	samplepos_t  sample_at (Beats const & qn) const { return _tempo->sample_at (qn); }
 	Beats        quarters_at (BBT_Time const & bbt) const { return _meter->quarters_at (bbt); }
-	BBT_Argument     bbt_at (Beats const & beats) const { return BBT_Argument (reftime(), _meter->bbt_at (beats)); }
+	BBT_Time     bbt_at (Beats const & beats) const { return _meter->bbt_at (beats); }
 
 	superclock_t superclocks_per_note_type () const { return _tempo->superclocks_per_note_type (); }
 	superclock_t end_superclocks_per_note_type () const {return _tempo->end_superclocks_per_note_type (); }
@@ -497,9 +495,9 @@ class LIBTEMPORAL_API TempoMetric
 	int note_type () const { return _tempo->note_type(); }
 	int divisions_per_bar () const { return _meter->divisions_per_bar(); }
 	int note_value() const { return _meter->note_value(); }
-	BBT_Argument   bbt_add (BBT_Time const & bbt, BBT_Offset const & add) const { return BBT_Argument (reftime(), _meter->bbt_add (bbt, add)); }
-	BBT_Argument   bbt_subtract (BBT_Time const & bbt, BBT_Offset const & sub) const { return BBT_Argument (reftime(), _meter->bbt_subtract (bbt, sub)); }
-	BBT_Argument round_to_bar (BBT_Time const & bbt) const { return BBT_Argument (reftime(), _meter->round_to_bar (bbt)); }
+	BBT_Time   bbt_add (BBT_Time const & bbt, BBT_Offset const & add) const { return _meter->bbt_add (bbt, add); }
+	BBT_Time   bbt_subtract (BBT_Time const & bbt, BBT_Offset const & sub) const { return _meter->bbt_subtract (bbt, sub); }
+	BBT_Time round_to_bar (BBT_Time const & bbt) const { return _meter->round_to_bar (bbt); }
 	Beats to_quarters (BBT_Offset const & bbo) const { return _meter->to_quarters (bbo); }
 
 	/* combination methods that require both tempo and meter information */
@@ -522,7 +520,7 @@ class LIBTEMPORAL_API TempoMetric
 		return int_div_round (superclocks_per_note_type_at_superclock (sc) * _tempo->note_type(), (int64_t) _meter->note_value());
 	}
 
-	BBT_Argument bbt_at (timepos_t const &) const;
+	BBT_Time bbt_at (timepos_t const &) const;
 	superclock_t superclock_at (BBT_Time const &) const;
 
 	samplepos_t samples_per_bar (samplecnt_t sr) const {
@@ -855,12 +853,12 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 	LIBTEMPORAL_API double quarters_per_minute_at (timepos_t const & pos) const;
 
 	/* convenience function */
-	LIBTEMPORAL_API BBT_Argument round_to_bar (BBT_Argument const & bbt) const {
-		return metric_at (bbt).round_to_bar (bbt);
+	LIBTEMPORAL_API BBT_Time round_to_bar (BBT_Argument const & bbt) const {
+		return metric_at (bbt).meter().round_to_bar (bbt);
 	}
 
-	LIBTEMPORAL_API BBT_Argument bbt_at (timepos_t const &) const;
-	LIBTEMPORAL_API BBT_Argument bbt_at (Beats const &) const;
+	LIBTEMPORAL_API BBT_Time bbt_at (timepos_t const &) const;
+	LIBTEMPORAL_API BBT_Time bbt_at (Beats const &) const;
 
 	LIBTEMPORAL_API	Beats quarters_at (BBT_Argument const &) const;
 	LIBTEMPORAL_API	Beats quarters_at (timepos_t const &) const;
@@ -886,7 +884,7 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 
 	LIBTEMPORAL_API	Temporal::timecnt_t convert_duration (Temporal::timecnt_t const & duration, Temporal::timepos_t const &, Temporal::TimeDomain domain) const;
 
-	LIBTEMPORAL_API	BBT_Argument bbt_walk (BBT_Argument const &, BBT_Offset const &) const;
+	LIBTEMPORAL_API	BBT_Time bbt_walk (BBT_Argument const &, BBT_Offset const &) const;
 
 	LIBTEMPORAL_API	void get_grid (TempoMapPoints & points, superclock_t start, superclock_t end, uint32_t bar_mod = 0, uint32_t beat_div = 1) const;
 	LIBTEMPORAL_API	uint32_t count_bars (Beats const & start, Beats const & end) const;
@@ -945,7 +943,7 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 
 	void copy_points (TempoMap const & other);
 
-	BBT_Argument bbt_at (superclock_t sc) const;
+	BBT_Time bbt_at (superclock_t sc) const;
 
 	template<typename T, typename T1> struct const_traits {
 		typedef Points::const_iterator iterator_type;
diff --git a/libs/temporal/timeline.cc b/libs/temporal/timeline.cc
index 07f1c6d462..2c2798e2e1 100644
--- a/libs/temporal/timeline.cc
+++ b/libs/temporal/timeline.cc
@@ -664,7 +664,7 @@ timepos_t::earlier (Temporal::BBT_Offset const & offset) const
 	TempoMap::SharedPtr tm (TempoMap::use());
 
 	if (is_superclock()) {
-		return timepos_t (tm->superclock_at (BBT_Argument (*this, tm->bbt_walk (BBT_Argument (*this, tm->bbt_at (*this)), -offset))));
+		return timepos_t (tm->superclock_at (tm->bbt_walk (tm->bbt_at (*this), -offset)));
 	}
 
 	return timepos_t (tm->bbtwalk_to_quarters (beats(), -offset));
@@ -763,7 +763,7 @@ timepos_t::shift_earlier (Temporal::BBT_Offset const & offset)
 	TempoMap::SharedPtr tm (TempoMap::use());
 
 	if (is_superclock()) {
-		v = build (false, (tm->superclock_at (tm->bbt_walk (BBT_Argument (*this, tm->bbt_at (*this)), -offset))));
+		v = build (false, (tm->superclock_at (tm->bbt_walk (tm->bbt_at (*this), -offset))));
 	} else {
 		v = build (true, tm->bbtwalk_to_quarters (beats(), -offset).to_ticks());
 	}
@@ -780,7 +780,7 @@ timepos_t::operator+= (Temporal::BBT_Offset const & offset)
 	if (is_beats()) {
 		v = build (true, tm->bbtwalk_to_quarters (beats(), offset).to_ticks());
 	} else {
-		v = build (false, tm->superclock_at (tm->bbt_walk (BBT_Argument (*this, tm->bbt_at (*this)), offset)));
+		v = build (false, tm->superclock_at (tm->bbt_walk (tm->bbt_at (*this), offset)));
 	}
 
 	return *this;
-- 
2.37.2