harden TempoMap::next_tempo_section () a bit.
[ardour.git] / libs / ardour / tempo.cc
index 4d0b74d2440fc3881f2ac4e16564305582436cea..3865fe3e197ba05575a8885c8a26c5ac12333a86 100644 (file)
@@ -45,7 +45,7 @@ using Timecode::BBT_Time;
 /* _default tempo is 4/4 qtr=120 */
 
 Meter    TempoMap::_default_meter (4.0, 4.0);
-Tempo    TempoMap::_default_tempo (120.0, 4.0);
+Tempo    TempoMap::_default_tempo (120.0, 4.0, 120.0);
 
 framepos_t
 MetricSection::frame_at_minute (const double& time) const
@@ -71,7 +71,7 @@ Meter::frames_per_grid (const Tempo& tempo, framecnt_t sr) const
           The return value IS NOT interpretable in terms of "beats".
        */
 
-       return (60.0 * sr) / (tempo.note_types_per_minute() * (_note_type/tempo.note_type()));
+       return (60.0 * sr) / (tempo.note_types_per_minute() * (_note_type / tempo.note_type()));
 }
 
 double
@@ -90,6 +90,7 @@ TempoSection::TempoSection (const XMLNode& node, framecnt_t sample_rate)
        , _c (0.0)
        , _active (true)
        , _locked_to_meter (false)
+       , _legacy_end (false)
 {
        XMLProperty const * prop;
        LocaleGuard lg;
@@ -143,7 +144,28 @@ TempoSection::TempoSection (const XMLNode& node, framecnt_t sample_rate)
                if (sscanf (prop->value().c_str(), "%lf", &_note_type) != 1 || _note_type < 1.0) {
                        error << _("TempoSection XML node has an illegal \"note-type\" value") << endmsg;
                        throw failed_constructor();
+               }
+       }
+
+       /* XX replace old end-beats-per-minute name with note-types-per-minute */
+       if ((prop = node.property ("end-beats-per-minute")) != 0) {
+               if (sscanf (prop->value().c_str(), "%lf", &_end_note_types_per_minute) != 1 || _end_note_types_per_minute < 0.0) {
+                       info << _("TempoSection XML node has an illegal \"in-beats-per-minute\" value") << endmsg;
+                       //throw failed_constructor();
+                       _end_note_types_per_minute = _note_types_per_minute;
+                       _legacy_end = true;
+               }
+       } else {
+               _legacy_end = true;
        }
+
+       if ((prop = node.property ("tempo-type")) != 0) {
+               TempoSection::Type old_type;
+
+               old_type = Type (string_2_enum (prop->value(), old_type));
+               if (old_type == TempoSection::Constant) {
+                       _end_note_types_per_minute = _note_types_per_minute;
+               }
        }
 
        if ((prop = node.property ("movable")) == 0) {
@@ -160,12 +182,6 @@ TempoSection::TempoSection (const XMLNode& node, framecnt_t sample_rate)
                set_active (string_is_affirmative (prop->value()));
        }
 
-       if ((prop = node.property ("tempo-type")) == 0) {
-               _type = Constant;
-       } else {
-               _type = Type (string_2_enum (prop->value(), _type));
-       }
-
        if ((prop = node.property ("lock-style")) == 0) {
                if (!initial()) {
                        set_position_lock_style (MusicTime);
@@ -177,10 +193,19 @@ TempoSection::TempoSection (const XMLNode& node, framecnt_t sample_rate)
        }
 
        if ((prop = node.property ("locked-to-meter")) == 0) {
-               set_locked_to_meter (false);
+               if (initial()) {
+                       set_locked_to_meter (true);
+               } else {
+                       set_locked_to_meter (false);
+               }
        } else {
                set_locked_to_meter (string_is_affirmative (prop->value()));
        }
+
+       /* 5.5 marked initial tempo as not locked to meter. this should always be true anyway */
+       if (initial()) {
+               set_locked_to_meter (true);
+       }
 }
 
 XMLNode&
@@ -198,34 +223,29 @@ TempoSection::get_state() const
        root->add_property ("beats-per-minute", buf);
        snprintf (buf, sizeof (buf), "%lf", _note_type);
        root->add_property ("note-type", buf);
+       snprintf (buf, sizeof (buf), "%lf", _end_note_types_per_minute);
+       root->add_property ("end-beats-per-minute", buf);
        snprintf (buf, sizeof (buf), "%s", !initial()?"yes":"no");
        root->add_property ("movable", buf);
        snprintf (buf, sizeof (buf), "%s", active()?"yes":"no");
        root->add_property ("active", buf);
-       root->add_property ("tempo-type", enum_2_string (_type));
        root->add_property ("lock-style", enum_2_string (position_lock_style()));
        root->add_property ("locked-to-meter", locked_to_meter()?"yes":"no");
 
        return *root;
 }
 
-void
-TempoSection::set_type (Type type)
-{
-       _type = type;
-}
-
 /** returns the Tempo at the session-relative minute.
 */
 Tempo
 TempoSection::tempo_at_minute (const double& m) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && m < minute());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && m < minute());
        if (constant) {
                return Tempo (note_types_per_minute(), note_type());
        }
 
-       return Tempo (_tempo_at_time (m - minute()), _note_type);
+       return Tempo (_tempo_at_time (m - minute()), _note_type, _end_note_types_per_minute);
 }
 
 /** returns the session relative minute where the supplied tempo in note types per minute occurs.
@@ -246,7 +266,7 @@ TempoSection::tempo_at_minute (const double& m) const
 double
 TempoSection::minute_at_ntpm (const double& ntpm, const double& p) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && p < pulse());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && p < pulse());
        if (constant) {
                return ((p - pulse()) / pulses_per_minute()) + minute();
        }
@@ -259,13 +279,13 @@ TempoSection::minute_at_ntpm (const double& ntpm, const double& p) const
 Tempo
 TempoSection::tempo_at_pulse (const double& p) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && p < pulse());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && p < pulse());
 
        if (constant) {
                return Tempo (note_types_per_minute(), note_type());
        }
 
-       return Tempo (_tempo_at_pulse (p - pulse()), _note_type);
+       return Tempo (_tempo_at_pulse (p - pulse()), _note_type, _end_note_types_per_minute);
 }
 
 /** returns the whole-note pulse where a tempo in note types per minute occurs.
@@ -281,7 +301,7 @@ TempoSection::tempo_at_pulse (const double& p) const
 double
 TempoSection::pulse_at_ntpm (const double& ntpm, const double& m) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && m < minute());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && m < minute());
        if (constant) {
                return ((m - minute()) * pulses_per_minute()) + pulse();
        }
@@ -294,7 +314,7 @@ TempoSection::pulse_at_ntpm (const double& ntpm, const double& m) const
 double
 TempoSection::pulse_at_minute (const double& m) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && m < minute());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && m < minute());
        if (constant) {
                return ((m - minute()) * pulses_per_minute()) + pulse();
        }
@@ -307,7 +327,7 @@ TempoSection::pulse_at_minute (const double& m) const
 double
 TempoSection::minute_at_pulse (const double& p) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && p < pulse());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && p < pulse());
        if (constant) {
                return ((p - pulse()) / pulses_per_minute()) + minute();
        }
@@ -324,7 +344,7 @@ TempoSection::minute_at_pulse (const double& p) const
 double
 TempoSection::pulse_at_frame (const framepos_t& f) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && f < frame());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && f < frame());
        if (constant) {
                return (minute_at_frame (f - frame()) * pulses_per_minute()) + pulse();
        }
@@ -335,7 +355,7 @@ TempoSection::pulse_at_frame (const framepos_t& f) const
 framepos_t
 TempoSection::frame_at_pulse (const double& p) const
 {
-       const bool constant = _type == Constant || _c == 0.0 || (initial() && p < pulse());
+       const bool constant = type() == Constant || _c == 0.0 || (initial() && p < pulse());
        if (constant) {
                return frame_at_minute (((p - pulse()) / pulses_per_minute()) + minute());
        }
@@ -424,9 +444,9 @@ https://www.zhdk.ch/fileadmin/data_subsites/data_icst/Downloads/Timegrid/ICST_Te
  * @return the calculated function constant
 */
 double
-TempoSection::compute_c_func_pulse (const double& end_npm, const double& end_pulse) const
+TempoSection::compute_c_pulse (const double& end_npm, const double& end_pulse) const
 {
-       if (note_types_per_minute() == end_npm || _type == Constant) {
+       if (note_types_per_minute() == end_npm || type() == Constant) {
                return 0.0;
        }
 
@@ -440,9 +460,9 @@ TempoSection::compute_c_func_pulse (const double& end_npm, const double& end_pul
  * @return the calculated function constant
 */
 double
-TempoSection::compute_c_func_minute (const double& end_npm, const double& end_minute) const
+TempoSection::compute_c_minute (const double& end_npm, const double& end_minute) const
 {
-       if (note_types_per_minute() == end_npm || _type == Constant) {
+       if (note_types_per_minute() == end_npm || type() == Constant) {
                return 0.0;
        }
 
@@ -739,7 +759,7 @@ TempoMap::TempoMap (framecnt_t fr)
        _frame_rate = fr;
        BBT_Time start (1, 1, 0);
 
-       TempoSection *t = new TempoSection (0.0, 0.0, _default_tempo.note_types_per_minute(), _default_tempo.note_type(), TempoSection::Ramp, AudioTime, fr);
+       TempoSection *t = new TempoSection (0.0, 0.0, _default_tempo, AudioTime, fr);
        MeterSection *m = new MeterSection (0.0, 0.0, 0.0, start, _default_meter.divisions_per_bar(), _default_meter.note_divisor(), AudioTime, fr);
 
        t->set_initial (true);
@@ -967,10 +987,6 @@ TempoMap::do_insert (MetricSection* section)
 
                                        *(dynamic_cast<Tempo*>(*i)) = *(dynamic_cast<Tempo*>(insert_tempo));
                                        (*i)->set_position_lock_style (AudioTime);
-                                       TempoSection* t;
-                                       if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
-                                               t->set_type (insert_tempo->type());
-                                       }
                                        need_add = false;
                                } else {
                                        delete (*i);
@@ -1058,7 +1074,7 @@ TempoMap::do_insert (MetricSection* section)
 }
 /* user supplies the exact pulse if pls == MusicTime */
 TempoSection*
-TempoMap::add_tempo (const Tempo& tempo, const double& pulse, const framepos_t& frame, ARDOUR::TempoSection::Type type, PositionLockStyle pls)
+TempoMap::add_tempo (const Tempo& tempo, const double& pulse, const framepos_t& frame, PositionLockStyle pls)
 {
        if (tempo.note_types_per_minute() <= 0.0) {
                warning << "Cannot add tempo. note types per minute must be greater than zero." << endmsg;
@@ -1066,11 +1082,29 @@ TempoMap::add_tempo (const Tempo& tempo, const double& pulse, const framepos_t&
        }
 
        TempoSection* ts = 0;
+       TempoSection* prev_tempo = 0;
        {
                Glib::Threads::RWLock::WriterLock lm (lock);
-               ts = add_tempo_locked (tempo, pulse, minute_at_frame (frame), type, pls, true);
-       }
+               ts = add_tempo_locked (tempo, pulse, minute_at_frame (frame), pls, true);
+               for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
 
+                       if ((*i)->is_tempo()) {
+                               TempoSection* const this_t = static_cast<TempoSection*> (*i);
+
+                               bool const ipm = ts->position_lock_style() == MusicTime;
+                               bool const lm = ts->locked_to_meter();
+                               if ((ipm && this_t->pulse() == ts->pulse()) || (!ipm && this_t->frame() == ts->frame())
+                                   || (lm && this_t->pulse() == ts->pulse())) {
+                                       if (prev_tempo && prev_tempo->type() == TempoSection::Ramp) {
+                                               prev_tempo->set_end_note_types_per_minute (ts->note_types_per_minute());
+                                       }
+                                       break;
+                               }
+                               prev_tempo = this_t;
+                       }
+               }
+               recompute_map (_metrics);
+       }
 
        PropertyChanged (PropertyChange ());
 
@@ -1078,7 +1112,7 @@ TempoMap::add_tempo (const Tempo& tempo, const double& pulse, const framepos_t&
 }
 
 void
-TempoMap::replace_tempo (TempoSection& ts, const Tempo& tempo, const double& pulse, const framepos_t& frame, TempoSection::Type type, PositionLockStyle pls)
+TempoMap::replace_tempo (TempoSection& ts, const Tempo& tempo, const double& pulse, const framepos_t& frame, PositionLockStyle pls)
 {
        if (tempo.note_types_per_minute() <= 0.0) {
                warning << "Cannot replace tempo. note types per minute must be greater than zero." << endmsg;
@@ -1086,13 +1120,13 @@ TempoMap::replace_tempo (TempoSection& ts, const Tempo& tempo, const double& pul
        }
 
        const bool locked_to_meter = ts.locked_to_meter();
+       TempoSection* new_ts = 0;
 
        {
                Glib::Threads::RWLock::WriterLock lm (lock);
                TempoSection& first (first_tempo());
                if (!ts.initial()) {
-                       if (ts.locked_to_meter()) {
-                               ts.set_type (type);
+                       if (locked_to_meter) {
                                {
                                        /* cannot move a meter-locked tempo section */
                                        *static_cast<Tempo*>(&ts) = tempo;
@@ -1100,19 +1134,40 @@ TempoMap::replace_tempo (TempoSection& ts, const Tempo& tempo, const double& pul
                                }
                        } else {
                                remove_tempo_locked (ts);
-                               add_tempo_locked (tempo, pulse, minute_at_frame (frame), type, pls, true, locked_to_meter);
+                               new_ts = add_tempo_locked (tempo, pulse, minute_at_frame (frame), pls, true, locked_to_meter);
+
+                               if (new_ts && new_ts->type() == TempoSection::Constant) {
+                                       new_ts->set_end_note_types_per_minute (new_ts->note_types_per_minute());
+                               } else {
+                                       for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
+
+                                               if ((*i)->is_tempo()) {
+                                                       TempoSection* const this_t = static_cast<TempoSection*> (*i);
+
+                                                       bool const ipm = new_ts->position_lock_style() == MusicTime;
+                                                       bool const lm = new_ts->locked_to_meter();
+                                                       if ((ipm && this_t->pulse() > new_ts->pulse()) || (!ipm && this_t->frame() > new_ts->frame())
+                                                           || (lm && this_t->pulse() > new_ts->pulse())) {
+                                                               new_ts->set_end_note_types_per_minute (tempo.end_note_types_per_minute());
+
+                                                               break;
+                                                       }
+                                               }
+                                       }
+                               }
                        }
+
                } else {
-                       first.set_type (type);
                        first.set_pulse (0.0);
                        first.set_minute (minute_at_frame (frame));
                        first.set_position_lock_style (AudioTime);
+                       first.set_locked_to_meter (true);
                        {
                                /* cannot move the first tempo section */
                                *static_cast<Tempo*>(&first) = tempo;
-                               recompute_map (_metrics);
                        }
                }
+               recompute_map (_metrics);
        }
 
        PropertyChanged (PropertyChange ());
@@ -1120,27 +1175,22 @@ TempoMap::replace_tempo (TempoSection& ts, const Tempo& tempo, const double& pul
 
 TempoSection*
 TempoMap::add_tempo_locked (const Tempo& tempo, double pulse, double minute
-                           , TempoSection::Type type, PositionLockStyle pls, bool recompute, bool locked_to_meter)
+                           , PositionLockStyle pls, bool recompute, bool locked_to_meter)
 {
-       TempoSection* t = new TempoSection (pulse, minute, tempo.note_types_per_minute(), tempo.note_type(), type, pls, _frame_rate);
+       TempoSection* t = new TempoSection (pulse, minute, tempo, pls, _frame_rate);
        t->set_locked_to_meter (locked_to_meter);
-       bool solved = false;
 
        do_insert (t);
 
        if (recompute) {
                if (pls == AudioTime) {
-                       solved = solve_map_minute (_metrics, t, t->minute());
+                       solve_map_minute (_metrics, t, t->minute());
                } else {
-                       solved = solve_map_pulse (_metrics, t, t->pulse());
+                       solve_map_pulse (_metrics, t, t->pulse());
                }
                recompute_meters (_metrics);
        }
 
-       if (!solved && recompute) {
-               recompute_map (_metrics);
-       }
-
        return t;
 }
 
@@ -1181,10 +1231,11 @@ TempoMap::replace_meter (const MeterSection& ms, const Meter& meter, const BBT_T
                        *static_cast<Meter*>(&first) = meter;
                        first.set_position_lock_style (AudioTime);
                        first.set_pulse (0.0);
-                       //first.set_minute (minute_at_frame (frame));
+                       first.set_minute (minute_at_frame (frame));
                        pair<double, BBT_Time> beat = make_pair (0.0, BBT_Time (1, 1, 0));
                        first.set_beat (beat);
                        first_t.set_minute (first.minute());
+                       first_t.set_locked_to_meter (true);
                        first_t.set_pulse (0.0);
                        first_t.set_position_lock_style (AudioTime);
                        recompute_map (_metrics);
@@ -1204,7 +1255,7 @@ TempoMap::add_meter_locked (const Meter& meter, double beat, const BBT_Time& whe
 
        if (pls == AudioTime) {
                /* add meter-locked tempo */
-               mlt = add_tempo_locked (tempo_at_minute_locked (_metrics, time_minutes), pulse, minute_at_frame (frame), TempoSection::Ramp, AudioTime, true, true);
+               mlt = add_tempo_locked (tempo_at_minute_locked (_metrics, time_minutes), pulse, minute_at_frame (frame), AudioTime, true, true);
 
                if (!mlt) {
                        return 0;
@@ -1250,9 +1301,9 @@ TempoMap::add_meter_locked (const Meter& meter, double beat, const BBT_Time& whe
 }
 
 void
-TempoMap::change_initial_tempo (double note_types_per_minute, double note_type)
+TempoMap::change_initial_tempo (double note_types_per_minute, double note_type, double end_note_types_per_minute)
 {
-       Tempo newtempo (note_types_per_minute, note_type);
+       Tempo newtempo (note_types_per_minute, note_type, end_note_types_per_minute);
        TempoSection* t;
 
        for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
@@ -1272,9 +1323,9 @@ TempoMap::change_initial_tempo (double note_types_per_minute, double note_type)
 }
 
 void
-TempoMap::change_existing_tempo_at (framepos_t where, double note_types_per_minute, double note_type)
+TempoMap::change_existing_tempo_at (framepos_t where, double note_types_per_minute, double note_type, double end_ntpm)
 {
-       Tempo newtempo (note_types_per_minute, note_type);
+       Tempo newtempo (note_types_per_minute, note_type, end_ntpm);
 
        TempoSection* prev;
        TempoSection* first;
@@ -1422,14 +1473,14 @@ TempoMap::recompute_tempi (Metrics& metrics)
                        }
                        if (prev_t) {
                                if (t->position_lock_style() == AudioTime) {
-                                       prev_t->set_c (prev_t->compute_c_func_minute (t->note_types_per_minute(), t->minute()));
+                                       prev_t->set_c (prev_t->compute_c_minute (prev_t->end_note_types_per_minute(), t->minute()));
                                        if (!t->locked_to_meter()) {
-                                               t->set_pulse (prev_t->pulse_at_ntpm (t->note_types_per_minute(), t->minute()));
+                                               t->set_pulse (prev_t->pulse_at_ntpm (prev_t->end_note_types_per_minute(), t->minute()));
                                        }
 
                                } else {
-                                       prev_t->set_c (prev_t->compute_c_func_pulse (t->note_types_per_minute(), t->pulse()));
-                                       t->set_minute (prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()));
+                                       prev_t->set_c (prev_t->compute_c_pulse (prev_t->end_note_types_per_minute(), t->pulse()));
+                                       t->set_minute (prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()));
 
                                }
                        }
@@ -1462,7 +1513,7 @@ TempoMap::recompute_meters (Metrics& metrics)
                                        TempoSection* t;
                                        if ((*ii)->is_tempo()) {
                                                t = static_cast<TempoSection*> (*ii);
-                                               if ((t->locked_to_meter() || t->initial()) && t->frame() == meter->frame()) {
+                                               if (t->locked_to_meter() && t->frame() == meter->frame()) {
                                                        meter_locked_tempo = t;
                                                        break;
                                                }
@@ -1683,6 +1734,11 @@ TempoMap::minute_at_beat_locked (const Metrics& metrics, const double& beat) con
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                if ((*i)->is_tempo()) {
                        t = static_cast<TempoSection*> (*i);
+
+                       if (!t->active()) {
+                               continue;
+                       }
+
                        if (prev_t && ((t->pulse() - prev_m->pulse()) * prev_m->note_divisor()) + prev_m->beat() > beat) {
                                break;
                        }
@@ -1729,7 +1785,7 @@ TempoMap::tempo_at_minute_locked (const Metrics& metrics, const double& minute)
                }
        }
 
-       return Tempo (prev_t->note_types_per_minute(), prev_t->note_type());
+       return Tempo (prev_t->note_types_per_minute(), prev_t->note_type(), prev_t->end_note_types_per_minute());
 }
 
 /** returns the frame at which the supplied tempo occurs, or
@@ -1762,17 +1818,20 @@ TempoMap::minute_at_tempo_locked (const Metrics& metrics, const Tempo& tempo) co
                                continue;
                        }
 
-                       const double t_bpm = t->note_types_per_minute();
 
-                       if (t_bpm == tempo_bpm) {
+
+                       if (t->note_types_per_minute() == tempo_bpm) {
                                return t->minute();
                        }
 
                        if (prev_t) {
                                const double prev_t_bpm = prev_t->note_types_per_minute();
+                               const double prev_t_end_bpm = prev_t->end_note_types_per_minute();
+                               if ((prev_t_bpm > tempo_bpm && prev_t_end_bpm < tempo_bpm)
+                                   || (prev_t_bpm < tempo_bpm && prev_t_end_bpm > tempo_bpm)
+                                   || (prev_t_end_bpm == tempo_bpm)) {
 
-                               if ((t_bpm > tempo_bpm && prev_t_bpm < tempo_bpm) || (t_bpm < tempo_bpm && prev_t_bpm > tempo_bpm)) {
-                                       return prev_t->minute_at_ntpm (prev_t->note_types_per_minute(), prev_t->pulse());
+                                       return prev_t->minute_at_ntpm (tempo_bpm, t->pulse());
                                }
                        }
                        prev_t = t;
@@ -1803,7 +1862,7 @@ TempoMap::tempo_at_pulse_locked (const Metrics& metrics, const double& pulse) co
                }
        }
 
-       return Tempo (prev_t->note_types_per_minute(), prev_t->note_type());
+       return Tempo (prev_t->note_types_per_minute(), prev_t->note_type(), prev_t->end_note_types_per_minute());
 }
 
 double
@@ -2237,24 +2296,31 @@ TempoMap::bbt_at_frame (framepos_t frame)
                bbt.bars = 1;
                bbt.beats = 1;
                bbt.ticks = 0;
+#ifndef NDEBUG
                warning << string_compose (_("tempo map was asked for BBT time at frame %1\n"), frame) << endmsg;
+#endif
                return bbt;
        }
+
+       const double minute =  minute_at_frame (frame);
+
        Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       return bbt_at_minute_locked (_metrics, minute_at_frame (frame));
+       return bbt_at_minute_locked (_metrics, minute);
 }
 
 BBT_Time
 TempoMap::bbt_at_frame_rt (framepos_t frame)
 {
+       const double minute =  minute_at_frame (frame);
+
        Glib::Threads::RWLock::ReaderLock lm (lock, Glib::Threads::TRY_LOCK);
 
        if (!lm.locked()) {
                throw std::logic_error ("TempoMap::bbt_at_frame_rt() could not lock tempo map");
        }
 
-       return bbt_at_minute_locked (_metrics, minute_at_frame (frame));
+       return bbt_at_minute_locked (_metrics, minute);
 }
 
 Timecode::BBT_Time
@@ -2336,16 +2402,23 @@ framepos_t
 TempoMap::frame_at_bbt (const BBT_Time& bbt)
 {
        if (bbt.bars < 1) {
+#ifndef NDEBUG
                warning << string_compose (_("tempo map asked for frame time at bar < 1  (%1)\n"), bbt) << endmsg;
+#endif
                return 0;
        }
 
        if (bbt.beats < 1) {
                throw std::logic_error ("beats are counted from one");
        }
-       Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       return frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
+       double minute;
+       {
+               Glib::Threads::RWLock::ReaderLock lm (lock);
+               minute = minute_at_bbt_locked (_metrics, bbt);
+       }
+
+       return frame_at_minute (minute);
 }
 
 /* meter & tempo section based */
@@ -2368,33 +2441,25 @@ TempoMap::minute_at_bbt_locked (const Metrics& metrics, const BBT_Time& bbt) con
 double
 TempoMap::quarter_note_at_frame (const framepos_t frame) const
 {
-       Glib::Threads::RWLock::ReaderLock lm (lock);
-
-       const double ret = quarter_note_at_minute_locked (_metrics, minute_at_frame (frame));
+       const double minute =  minute_at_frame (frame);
 
-       return ret;
-}
-
-double
-TempoMap::quarter_note_at_minute_locked (const Metrics& metrics, const double minute) const
-{
-       const double ret = pulse_at_minute_locked (metrics, minute) * 4.0;
+       Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       return ret;
+       return pulse_at_minute_locked (_metrics, minute) * 4.0;
 }
 
 double
 TempoMap::quarter_note_at_frame_rt (const framepos_t frame) const
 {
+       const double minute =  minute_at_frame (frame);
+
        Glib::Threads::RWLock::ReaderLock lm (lock, Glib::Threads::TRY_LOCK);
 
        if (!lm.locked()) {
                throw std::logic_error ("TempoMap::quarter_note_at_frame_rt() could not lock tempo map");
        }
 
-       const double ret = pulse_at_minute_locked (_metrics, minute_at_frame (frame)) * 4.0;
-
-       return ret;
+       return pulse_at_minute_locked (_metrics, minute) * 4.0;
 }
 
 /**
@@ -2408,19 +2473,14 @@ TempoMap::quarter_note_at_frame_rt (const framepos_t frame) const
 framepos_t
 TempoMap::frame_at_quarter_note (const double quarter_note) const
 {
-       Glib::Threads::RWLock::ReaderLock lm (lock);
-
-       const framepos_t ret = frame_at_minute (minute_at_quarter_note_locked (_metrics, quarter_note));
-
-       return ret;
-}
+       double minute;
+       {
+               Glib::Threads::RWLock::ReaderLock lm (lock);
 
-double
-TempoMap::minute_at_quarter_note_locked (const Metrics& metrics, const double quarter_note) const
-{
-       const double ret = minute_at_pulse_locked (metrics, quarter_note / 4.0);
+               minute = minute_at_pulse_locked (_metrics, quarter_note / 4.0);
+       }
 
-       return ret;
+       return frame_at_minute (minute);
 }
 
 /** Returns the quarter-note beats corresponding to the supplied BBT (meter-based) beat.
@@ -2435,17 +2495,7 @@ TempoMap::quarter_note_at_beat (const double beat) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       const double ret = quarter_note_at_beat_locked (_metrics, beat);
-
-       return ret;
-}
-
-double
-TempoMap::quarter_note_at_beat_locked (const Metrics& metrics, const double beat) const
-{
-       const double ret = pulse_at_beat_locked (metrics, beat) * 4.0;
-
-       return ret;
+       return pulse_at_beat_locked (_metrics, beat) * 4.0;
 }
 
 /** Returns the BBT (meter-based) beat position corresponding to the supplied quarter-note beats.
@@ -2460,16 +2510,7 @@ TempoMap::beat_at_quarter_note (const double quarter_note) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       const double ret = beat_at_quarter_note_locked (_metrics, quarter_note);
-
-       return ret;
-}
-
-double
-TempoMap::beat_at_quarter_note_locked (const Metrics& metrics, const double quarter_note) const
-{
-
-       return beat_at_pulse_locked (metrics, quarter_note / 4.0);
+       return beat_at_pulse_locked (_metrics, quarter_note / 4.0);
 }
 
 /** Returns the duration in frames between two supplied quarter-note beat positions.
@@ -2485,9 +2526,14 @@ TempoMap::beat_at_quarter_note_locked (const Metrics& metrics, const double quar
 framecnt_t
 TempoMap::frames_between_quarter_notes (const double start, const double end) const
 {
-       Glib::Threads::RWLock::ReaderLock lm (lock);
+       double minutes;
 
-       return frame_at_minute (minutes_between_quarter_notes_locked (_metrics, start, end));
+       {
+               Glib::Threads::RWLock::ReaderLock lm (lock);
+               minutes = minutes_between_quarter_notes_locked (_metrics, start, end);
+       }
+
+       return frame_at_minute (minutes);
 }
 
 double
@@ -2567,7 +2613,7 @@ TempoMap::check_solved (const Metrics& metrics) const
                                }
 
                                /* precision check ensures tempo and frames align.*/
-                               if (t->frame() != frame_at_minute (prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()))) {
+                               if (t->frame() != frame_at_minute (prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()))) {
                                        if (!t->locked_to_meter()) {
                                                return false;
                                        }
@@ -2678,20 +2724,20 @@ TempoMap::solve_map_minute (Metrics& imaginary, TempoSection* section, const dou
                                if (prev_t && !section_prev && ((sml && tlm && t->pulse() > section->pulse()) || (!tlm && t->minute() > minute))) {
                                        section_prev = prev_t;
 
-                                       section_prev->set_c (section_prev->compute_c_func_minute (section->note_types_per_minute(), minute));
+                                       section_prev->set_c (section_prev->compute_c_minute (section_prev->end_note_types_per_minute(), minute));
                                        if (!section->locked_to_meter()) {
-                                               section->set_pulse (section_prev->pulse_at_ntpm (section->note_types_per_minute(), minute));
+                                               section->set_pulse (section_prev->pulse_at_ntpm (section_prev->end_note_types_per_minute(), minute));
                                        }
                                        prev_t = section;
                                }
 
                                if (t->position_lock_style() == MusicTime) {
-                                       prev_t->set_c (prev_t->compute_c_func_pulse (t->note_types_per_minute(), t->pulse()));
-                                       t->set_minute (prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()));
+                                       prev_t->set_c (prev_t->compute_c_pulse (prev_t->end_note_types_per_minute(), t->pulse()));
+                                       t->set_minute (prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()));
                                } else {
-                                       prev_t->set_c (prev_t->compute_c_func_minute (t->note_types_per_minute(), t->minute()));
+                                       prev_t->set_c (prev_t->compute_c_minute (prev_t->end_note_types_per_minute(), t->minute()));
                                        if (!t->locked_to_meter()) {
-                                               t->set_pulse (prev_t->pulse_at_ntpm (t->note_types_per_minute(), t->minute()));
+                                               t->set_pulse (prev_t->pulse_at_ntpm (prev_t->end_note_types_per_minute(), t->minute()));
                                        }
                                }
                        }
@@ -2748,12 +2794,12 @@ TempoMap::solve_map_pulse (Metrics& imaginary, TempoSection* section, const doub
                                }
 
                                if (t->position_lock_style() == MusicTime) {
-                                       prev_t->set_c (prev_t->compute_c_func_pulse (t->note_types_per_minute(), t->pulse()));
-                                       t->set_minute (prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()));
+                                       prev_t->set_c (prev_t->compute_c_pulse (prev_t->end_note_types_per_minute(), t->pulse()));
+                                       t->set_minute (prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()));
                                } else {
-                                       prev_t->set_c (prev_t->compute_c_func_minute (t->note_types_per_minute(), t->minute()));
+                                       prev_t->set_c (prev_t->compute_c_minute (prev_t->end_note_types_per_minute(), t->minute()));
                                        if (!t->locked_to_meter()) {
-                                               t->set_pulse (prev_t->pulse_at_ntpm (t->note_types_per_minute(), t->minute()));
+                                               t->set_pulse (prev_t->pulse_at_ntpm (prev_t->end_note_types_per_minute(), t->minute()));
                                        }
                                }
                        }
@@ -2762,8 +2808,8 @@ TempoMap::solve_map_pulse (Metrics& imaginary, TempoSection* section, const doub
        }
 
        if (section_prev) {
-               section_prev->set_c (section_prev->compute_c_func_pulse (section->note_types_per_minute(), pulse));
-               section->set_minute (section_prev->minute_at_ntpm (section->note_types_per_minute(), pulse));
+               section_prev->set_c (section_prev->compute_c_pulse (section_prev->end_note_types_per_minute(), pulse));
+               section->set_minute (section_prev->minute_at_ntpm (section_prev->end_note_types_per_minute(), pulse));
        }
 
 #if (0)
@@ -2819,7 +2865,7 @@ TempoMap::solve_map_minute (Metrics& imaginary, MeterSection* section, const dou
                TempoSection* t;
                if ((*ii)->is_tempo()) {
                        t = static_cast<TempoSection*> (*ii);
-                       if ((t->locked_to_meter() || t->initial()) && t->frame() == section->frame()) {
+                       if (t->locked_to_meter() && t->frame() == section->frame()) {
                                meter_locked_tempo = t;
                                break;
                        }
@@ -2995,7 +3041,7 @@ TempoMap::solve_map_bbt (Metrics& imaginary, MeterSection* section, const BBT_Ti
                                        TempoSection* t;
                                        if ((*ii)->is_tempo()) {
                                                t = static_cast<TempoSection*> (*ii);
-                                               if ((t->locked_to_meter() || t->initial()) && t->frame() == m->frame()) {
+                                               if (t->locked_to_meter() && t->frame() == m->frame()) {
                                                        meter_locked_tempo = t;
                                                        break;
                                                }
@@ -3262,7 +3308,7 @@ TempoMap::gui_set_tempo_position (TempoSection* ts, const framepos_t& frame, con
                                         * in the future map rather than the existing one.
                                         */
                                        const double qn = exact_qn_at_frame_locked (future_map, frame, sub_num);
-                                       const framepos_t snapped_frame = frame_at_minute (minute_at_quarter_note_locked (future_map, qn));
+                                       const framepos_t snapped_frame = frame_at_minute (minute_at_pulse_locked (future_map, qn / 4.0));
 
                                        if (solve_map_minute (future_map, tempo_copy, minute_at_frame (snapped_frame))) {
                                                solve_map_minute (_metrics, ts, minute_at_frame (snapped_frame));
@@ -3283,7 +3329,7 @@ TempoMap::gui_set_tempo_position (TempoSection* ts, const framepos_t& frame, con
                ++d;
        }
 
-       MetricPositionChanged (); // Emit Signal
+       MetricPositionChanged (PropertyChange ()); // Emit Signal
 }
 
 /** moves a MeterSection to a specified position.
@@ -3331,22 +3377,39 @@ TempoMap::gui_set_meter_position (MeterSection* ms, const framepos_t& frame)
                ++d;
        }
 
-       MetricPositionChanged (); // Emit Signal
+       MetricPositionChanged (PropertyChange ()); // Emit Signal
 }
 
 bool
-TempoMap::gui_change_tempo (TempoSection* ts, const Tempo& bpm)
+TempoMap::gui_change_tempo (TempoSection* ts, const Tempo& bpm, bool change_end)
 {
        Metrics future_map;
        bool can_solve = false;
        {
                Glib::Threads::RWLock::WriterLock lm (lock);
                TempoSection* tempo_copy = copy_metrics_and_point (_metrics, future_map, ts);
-               tempo_copy->set_note_types_per_minute (bpm.note_types_per_minute());
+
+               if (change_end && tempo_copy->type() == TempoSection::Constant) {
+                       tempo_copy->set_end_note_types_per_minute (bpm.note_types_per_minute());
+                       tempo_copy->set_note_types_per_minute (bpm.note_types_per_minute());
+               } else if (change_end) {
+                       tempo_copy->set_end_note_types_per_minute (bpm.note_types_per_minute());
+               } else {
+                       tempo_copy->set_note_types_per_minute (bpm.note_types_per_minute());
+               }
+
                recompute_tempi (future_map);
 
                if (check_solved (future_map)) {
-                       ts->set_note_types_per_minute (bpm.note_types_per_minute());
+                       if (change_end && ts->type() == TempoSection::Constant) {
+                               ts->set_end_note_types_per_minute (bpm.note_types_per_minute());
+                               ts->set_note_types_per_minute (bpm.note_types_per_minute());
+                       } else if (change_end) {
+                               ts->set_end_note_types_per_minute (bpm.note_types_per_minute());
+                       } else {
+                               ts->set_note_types_per_minute (bpm.note_types_per_minute());
+                       }
+
                        recompute_map (_metrics);
                        can_solve = true;
                }
@@ -3358,13 +3421,14 @@ TempoMap::gui_change_tempo (TempoSection* ts, const Tempo& bpm)
                ++d;
        }
        if (can_solve) {
-               MetricPositionChanged (); // Emit Signal
+               MetricPositionChanged (PropertyChange ()); // Emit Signal
        }
+
        return can_solve;
 }
 
 void
-TempoMap::gui_stretch_tempo (TempoSection* ts, const framepos_t& frame, const framepos_t& end_frame)
+TempoMap::gui_stretch_tempo (TempoSection* ts, const framepos_t frame, const framepos_t end_frame)
 {
        /*
          Ts (future prev_t)   Tnext
@@ -3384,105 +3448,224 @@ TempoMap::gui_stretch_tempo (TempoSection* ts, const framepos_t& frame, const fr
                }
 
                TempoSection* prev_t = copy_metrics_and_point (_metrics, future_map, ts);
-               TempoSection* prev_to_prev_t = 0;
-               const frameoffset_t fr_off = end_frame - frame;
 
-               assert (prev_t);
+               if (!prev_t) {
+                       return;
+               }
+
+               /* minimum allowed measurement distance in frames */
+               framepos_t const min_dframe = 2;
 
-               if (prev_t->pulse() > 0.0) {
-                       prev_to_prev_t = const_cast<TempoSection*>(&tempo_section_at_minute_locked (future_map, minute_at_frame (prev_t->frame() - 1)));
+               double new_bpm;
+
+               if (frame > prev_t->frame() + min_dframe && end_frame > prev_t->frame() + min_dframe) {
+
+                       new_bpm = prev_t->note_types_per_minute() * ((frame - prev_t->frame())
+                                                                                  / (double) (end_frame - prev_t->frame()));
+               } else {
+                       new_bpm = prev_t->note_types_per_minute();
+               }
+
+               std::cout << "new bpm : " << new_bpm << std::endl;
+               new_bpm = min (new_bpm, (double) 1000.0);
+
+               /* don't clamp and proceed here.
+                  testing has revealed that this can go negative,
+                  which is an entirely different thing to just being too low.
+               */
+
+               if (new_bpm < 0.5) {
+                       goto out;
+               }
+
+               if (prev_t && prev_t->type() == TempoSection::Ramp) {
+                       prev_t->set_note_types_per_minute (new_bpm);
+               } else {
+                       prev_t->set_end_note_types_per_minute (new_bpm);
+                       prev_t->set_note_types_per_minute (new_bpm);
+               }
+
+               recompute_tempi (future_map);
+               recompute_meters (future_map);
+
+               if (check_solved (future_map)) {
+                       if (prev_t && prev_t->type() == TempoSection::Ramp) {
+                               ts->set_note_types_per_minute (new_bpm);
+                       } else {
+                               ts->set_end_note_types_per_minute (new_bpm);
+                               ts->set_note_types_per_minute (new_bpm);
+                       }
+                       recompute_tempi (_metrics);
+                       recompute_meters (_metrics);
                }
+       }
 
+       MetricPositionChanged (PropertyChange ()); // Emit Signal
+
+out:
+       Metrics::const_iterator d = future_map.begin();
+       while (d != future_map.end()) {
+               delete (*d);
+               ++d;
+       }
+
+}
+void
+TempoMap::gui_stretch_tempo_end (TempoSection* ts, const framepos_t frame, const framepos_t end_frame)
+{
+       /*
+         Ts (future prev_t)   Tnext
+         |                    |
+         |     [drag^]        |
+         |----------|----------
+               e_f  qn_beats(frame)
+       */
+
+       Metrics future_map;
+
+       {
+               Glib::Threads::RWLock::WriterLock lm (lock);
+
+               if (!ts) {
+                       return;
+               }
+
+               TempoSection* prev_t = copy_metrics_and_point (_metrics, future_map, ts);
+
+/*
                TempoSection* next_t = 0;
-               for (Metrics::iterator i = future_map.begin(); i != future_map.end(); ++i) {
-                       TempoSection* t = 0;
-                       if ((*i)->is_tempo()) {
-                               t = static_cast<TempoSection*> (*i);
-                               if (t->frame() > ts->frame()) {
-                                       next_t = t;
-                                       break;
-                               }
+               for (Metrics::const_iterator i = future_map.begin(); i != future_map.end(); ++i) {
+                       if ((*i)->is_tempo() && (*i)->minute() >  prev_t->minute()) {
+                               next_t = static_cast<TempoSection*> (*i);
+                               break;
                        }
                }
+
+               if (!next_t) {
+                       return;
+               }
+*/
+               if (!prev_t) {
+                       return;
+               }
+
+
                /* minimum allowed measurement distance in frames */
-               const framepos_t min_dframe = 2;
+               framepos_t const min_dframe = 2;
+               double new_bpm;
 
-               /* the change in frames is the result of changing the slope of at most 2 previous tempo sections.
-                  constant to constant is straightforward, as the tempo prev to prev_t has constant slope.
-               */
-               double contribution = 0.0;
+               if (frame > prev_t->frame() + min_dframe && end_frame > prev_t->frame() + min_dframe) {
+                       new_bpm = prev_t->end_note_types_per_minute() * ((frame - prev_t->frame())
+                                                                                / (double) (end_frame - prev_t->frame()));
+               } else {
+                       new_bpm = prev_t->end_note_types_per_minute();
+               }
 
-               if (next_t && prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
-                       contribution = (prev_t->frame() - prev_to_prev_t->frame()) / (double) (next_t->frame() - prev_to_prev_t->frame());
+               new_bpm = min (new_bpm, (double) 1000.0);
+
+               if (new_bpm < 0.5) {
+                       goto out;
                }
 
-               const frameoffset_t prev_t_frame_contribution = fr_off - (contribution * (double) fr_off);
+               prev_t->set_end_note_types_per_minute (new_bpm);
 
-               const double start_pulse = prev_t->pulse_at_minute (minute_at_frame (frame));
-               const double end_pulse = prev_t->pulse_at_minute (minute_at_frame (end_frame));
+               recompute_tempi (future_map);
+               recompute_meters (future_map);
 
-               double new_bpm;
+               if (check_solved (future_map)) {
+                       ts->set_end_note_types_per_minute (new_bpm);
 
-               if (prev_t->type() == TempoSection::Constant || prev_t->c() == 0.0) {
+                       recompute_tempi (_metrics);
+                       recompute_meters (_metrics);
+               }
+       }
 
-                       if (prev_t->position_lock_style() == MusicTime) {
-                               if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
-                                       if (frame > prev_to_prev_t->frame() + min_dframe && (frame + prev_t_frame_contribution) > prev_to_prev_t->frame() + min_dframe) {
+       MetricPositionChanged (PropertyChange ()); // Emit Signal
 
-                                               new_bpm = prev_t->note_types_per_minute() * ((frame - prev_to_prev_t->frame())
-                                                                                       / (double) ((frame + prev_t_frame_contribution) - prev_to_prev_t->frame()));
-                                       } else {
-                                               new_bpm = prev_t->note_types_per_minute();
-                                       }
-                               } else {
-                                       /* prev to prev is irrelevant */
+out:
+       Metrics::const_iterator d = future_map.begin();
+       while (d != future_map.end()) {
+               delete (*d);
+               ++d;
+       }
 
-                                       if (start_pulse > prev_t->pulse() && end_pulse > prev_t->pulse()) {
-                                               new_bpm = prev_t->note_types_per_minute() * ((start_pulse - prev_t->pulse()) / (end_pulse - prev_t->pulse()));
-                                       } else {
-                                               new_bpm = prev_t->note_types_per_minute();
-                                       }
-                               }
-                       } else {
-                               /* AudioTime */
-                               if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
-                                       if (frame > prev_to_prev_t->frame() + min_dframe && end_frame > prev_to_prev_t->frame() + min_dframe) {
+}
+bool
+TempoMap::gui_twist_tempi (TempoSection* ts, const Tempo& bpm, const framepos_t frame, const framepos_t end_frame)
+{
+       TempoSection* next_t = 0;
+       TempoSection* next_to_next_t = 0;
+       Metrics future_map;
+       bool can_solve = false;
 
-                                               new_bpm = prev_t->note_types_per_minute() * ((frame - prev_to_prev_t->frame())
-                                                                                       / (double) ((end_frame) - prev_to_prev_t->frame()));
-                                       } else {
-                                               new_bpm = prev_t->note_types_per_minute();
-                                       }
-                               } else {
-                                       /* prev_to_prev_t is irrelevant */
+       /* minimum allowed measurement distance in frames */
+       framepos_t const min_dframe = 2;
 
-                                       if (frame > prev_t->frame() + min_dframe && end_frame > prev_t->frame() + min_dframe) {
-                                               new_bpm = prev_t->note_types_per_minute() * ((frame - prev_t->frame()) / (double) (end_frame - prev_t->frame()));
-                                       } else {
-                                               new_bpm = prev_t->note_types_per_minute();
-                                       }
-                               }
+       {
+               Glib::Threads::RWLock::WriterLock lm (lock);
+               if (!ts) {
+                       return false;
+               }
+
+               TempoSection* tempo_copy = copy_metrics_and_point (_metrics, future_map, ts);
+               TempoSection* prev_to_prev_t = 0;
+               const frameoffset_t fr_off = end_frame - frame;
+
+               if (!tempo_copy) {
+                       return false;
+               }
+
+               if (tempo_copy->pulse() > 0.0) {
+                       prev_to_prev_t = const_cast<TempoSection*>(&tempo_section_at_minute_locked (future_map, minute_at_frame (tempo_copy->frame() - 1)));
+               }
+
+               for (Metrics::const_iterator i = future_map.begin(); i != future_map.end(); ++i) {
+                       if ((*i)->is_tempo() && (*i)->minute() >  tempo_copy->minute()) {
+                               next_t = static_cast<TempoSection*> (*i);
+                               break;
                        }
-               } else {
+               }
 
-                       double frame_ratio = 1.0;
-                       double pulse_ratio = 1.0;
-                       const double pulse_pos = frame;
+               if (!next_t) {
+                       return false;
+               }
 
-                       if (prev_to_prev_t) {
-                               if (pulse_pos > prev_to_prev_t->frame() + min_dframe && (pulse_pos - fr_off) > prev_to_prev_t->frame() + min_dframe) {
-                                       frame_ratio = (((pulse_pos - fr_off) - prev_to_prev_t->frame()) / (double) ((pulse_pos) - prev_to_prev_t->frame()));
-                               }
-                               if (end_pulse > prev_to_prev_t->pulse() && start_pulse > prev_to_prev_t->pulse()) {
-                                       pulse_ratio = ((start_pulse - prev_to_prev_t->pulse()) / (end_pulse - prev_to_prev_t->pulse()));
-                               }
-                       } else {
-                               if (pulse_pos > prev_t->frame() + min_dframe && (pulse_pos - fr_off) > prev_t->frame() + min_dframe) {
-                                       frame_ratio = (((pulse_pos - fr_off) - prev_t->frame()) / (double) ((pulse_pos) - prev_t->frame()));
-                               }
-                               pulse_ratio = (start_pulse / end_pulse);
+               for (Metrics::const_iterator i = future_map.begin(); i != future_map.end(); ++i) {
+                       if ((*i)->is_tempo() && (*i)->minute() >  next_t->minute()) {
+                               next_to_next_t = static_cast<TempoSection*> (*i);
+                               break;
                        }
-                       new_bpm = prev_t->note_types_per_minute() * (pulse_ratio * frame_ratio);
+               }
+
+               if (!next_to_next_t) {
+                       std::cout << "no next to next t" << std::endl;
+                       return false;
+               }
+
+               double prev_contribution = 0.0;
+
+               if (next_t && prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
+                       prev_contribution = (tempo_copy->frame() - prev_to_prev_t->frame()) / (double) (next_t->frame() - prev_to_prev_t->frame());
+               }
+
+               const frameoffset_t tempo_copy_frame_contribution = fr_off - (prev_contribution * (double) fr_off);
+
+
+               framepos_t old_tc_pos = tempo_copy->frame();
+               framepos_t old_next_pos = next_t->frame();
+               double old_next_minute = next_t->minute();
+               framepos_t old_next_to_next_pos = next_to_next_t->frame();
+               double old_next_to_next_minute = next_to_next_t->minute();
+
+               double new_bpm;
+               double new_next_bpm;
+               double new_copy_end_bpm;
+
+               if (frame > prev_to_prev_t->frame() + min_dframe && (frame + tempo_copy_frame_contribution) > prev_to_prev_t->frame() + min_dframe) {
+                       new_bpm = tempo_copy->note_types_per_minute() * ((frame - tempo_copy->frame())
+                                                                                      / (double) (end_frame - tempo_copy->frame()));
+               } else {
+                       new_bpm = tempo_copy->note_types_per_minute();
                }
 
                /* don't clamp and proceed here.
@@ -3490,17 +3673,95 @@ TempoMap::gui_stretch_tempo (TempoSection* ts, const framepos_t& frame, const fr
                   which is an entirely different thing to just being too low.
                */
                if (new_bpm < 0.5) {
-                       return;
+                       return false;
                }
+
                new_bpm = min (new_bpm, (double) 1000.0);
-               prev_t->set_note_types_per_minute (new_bpm);
+
+               tempo_copy->set_note_types_per_minute (new_bpm);
+               if (tempo_copy->type() == TempoSection::Constant) {
+                       tempo_copy->set_end_note_types_per_minute (new_bpm);
+               }
                recompute_tempi (future_map);
-               recompute_meters (future_map);
 
                if (check_solved (future_map)) {
+
+                       if (!next_t) {
+                               return false;
+                       }
                        ts->set_note_types_per_minute (new_bpm);
-                       recompute_tempi (_metrics);
-                       recompute_meters (_metrics);
+                       if (ts->type() == TempoSection::Constant) {
+                               ts->set_end_note_types_per_minute (new_bpm);
+                       }
+                       recompute_map (_metrics);
+                       can_solve = true;
+               }
+
+               if (next_t->type() == TempoSection::Constant || next_t->c() == 0.0) {
+                       if (frame > prev_to_prev_t->frame() + min_dframe && end_frame > prev_to_prev_t->frame() + min_dframe) {
+
+                               new_next_bpm = next_t->note_types_per_minute() * ((next_to_next_t->minute() - old_next_minute)
+                                                                                       / (double) ((old_next_to_next_minute) - old_next_minute));
+
+                       } else {
+                               new_next_bpm = next_t->note_types_per_minute();
+                       }
+
+                       next_t->set_note_types_per_minute (new_next_bpm);
+                       recompute_tempi (future_map);
+
+                       if (check_solved (future_map)) {
+                               for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
+                                       if ((*i)->is_tempo() && (*i)->minute() >  ts->minute()) {
+                                               next_t = static_cast<TempoSection*> (*i);
+                                               break;
+                                       }
+                               }
+
+                               if (!next_t) {
+                                       return false;
+                               }
+                               next_t->set_note_types_per_minute (new_next_bpm);
+                               recompute_map (_metrics);
+                               can_solve = true;
+                       }
+               } else {
+                       double next_frame_ratio = 1.0;
+                       double copy_frame_ratio = 1.0;
+
+                       if (next_to_next_t) {
+                               next_frame_ratio =  (next_to_next_t->frame() - old_next_pos) / (double) (old_next_to_next_pos -  old_next_pos);
+
+                               copy_frame_ratio =   ((old_tc_pos - next_t->frame()) / (double) (old_tc_pos - old_next_pos));
+
+                       } else {
+                               //next_frame_ratio = (((next_to_next_pos - fr_off) - next_t->frame()) / (double) ((next_to_next_pos) - next_t->frame()));
+                               //next_pulse_ratio = (start_pulse / end_pulse);
+                       }
+
+                       new_next_bpm = next_t->note_types_per_minute() * next_frame_ratio;
+                       new_copy_end_bpm =  tempo_copy->end_note_types_per_minute() * copy_frame_ratio;
+
+                       next_t->set_note_types_per_minute (new_next_bpm);
+                       tempo_copy->set_end_note_types_per_minute (new_copy_end_bpm);
+                       recompute_tempi (future_map);
+
+                       if (check_solved (future_map)) {
+                               for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
+                                       if ((*i)->is_tempo() && (*i)->minute() >  ts->minute()) {
+                                               next_t = static_cast<TempoSection*> (*i);
+                                               break;
+                                       }
+                               }
+
+                               if (!next_t) {
+                                       return false;
+                               }
+                               next_t->set_note_types_per_minute (new_next_bpm);
+                               ts->set_end_note_types_per_minute (new_copy_end_bpm);
+                               recompute_map (_metrics);
+                               can_solve = true;
+                       }
                }
        }
 
@@ -3509,10 +3770,12 @@ TempoMap::gui_stretch_tempo (TempoSection* ts, const framepos_t& frame, const fr
                delete (*d);
                ++d;
        }
+       if (can_solve) {
+               MetricPositionChanged (PropertyChange ()); // Emit Signal
+       }
 
-       MetricPositionChanged (); // Emit Signal
+       return can_solve;
 }
-
 /** Returns the exact bbt-based beat corresponding to the bar, beat or quarter note subdivision nearest to
  * the supplied frame, possibly returning a negative value.
  *
@@ -3582,13 +3845,13 @@ TempoMap::exact_qn_at_frame (const framepos_t& frame, const int32_t sub_num) con
 double
 TempoMap::exact_qn_at_frame_locked (const Metrics& metrics, const framepos_t& frame, const int32_t sub_num) const
 {
-       double qn = quarter_note_at_minute_locked (metrics, minute_at_frame (frame));
+       double qn = pulse_at_minute_locked (metrics, minute_at_frame (frame)) * 4.0;
 
        if (sub_num > 1) {
                qn = floor (qn) + (floor (((qn - floor (qn)) * (double) sub_num) + 0.5) / sub_num);
        } else if (sub_num == 1) {
                /* the gui requested exact musical (BBT) beat */
-               qn = quarter_note_at_beat_locked (metrics, floor (beat_at_minute_locked (metrics, minute_at_frame (frame)) + 0.5));
+               qn = pulse_at_beat_locked (metrics, (floor (beat_at_minute_locked (metrics, minute_at_frame (frame)) + 0.5))) * 4.0;
        } else if (sub_num == -1) {
                /* snap to  bar */
                Timecode::BBT_Time bbt = bbt_at_pulse_locked (metrics, qn / 4.0);
@@ -3684,119 +3947,23 @@ TempoMap::bbt_duration_at (framepos_t pos, const BBT_Time& bbt, int dir)
        return 0;
 }
 
-framepos_t
+MusicFrame
 TempoMap::round_to_bar (framepos_t fr, RoundMode dir)
 {
        return round_to_type (fr, dir, Bar);
 }
 
-framepos_t
+MusicFrame
 TempoMap::round_to_beat (framepos_t fr, RoundMode dir)
 {
        return round_to_type (fr, dir, Beat);
 }
 
-framepos_t
-TempoMap::round_to_beat_subdivision (framepos_t fr, int sub_num, RoundMode dir)
-{
-       Glib::Threads::RWLock::ReaderLock lm (lock);
-       uint32_t ticks = (uint32_t) floor (max (0.0, beat_at_minute_locked (_metrics, minute_at_frame (fr))) * BBT_Time::ticks_per_beat);
-       uint32_t beats = (uint32_t) floor (ticks / BBT_Time::ticks_per_beat);
-       uint32_t ticks_one_subdivisions_worth = (uint32_t) BBT_Time::ticks_per_beat / sub_num;
-
-       ticks -= beats * BBT_Time::ticks_per_beat;
-
-       if (dir > 0) {
-               /* round to next (or same iff dir == RoundUpMaybe) */
-
-               uint32_t mod = ticks % ticks_one_subdivisions_worth;
-
-               if (mod == 0 && dir == RoundUpMaybe) {
-                       /* right on the subdivision, which is fine, so do nothing */
-
-               } else if (mod == 0) {
-                       /* right on the subdivision, so the difference is just the subdivision ticks */
-                       ticks += ticks_one_subdivisions_worth;
-
-               } else {
-                       /* not on subdivision, compute distance to next subdivision */
-
-                       ticks += ticks_one_subdivisions_worth - mod;
-               }
-
-               if (ticks >= BBT_Time::ticks_per_beat) {
-                       ticks -= BBT_Time::ticks_per_beat;
-               }
-       } else if (dir < 0) {
-
-               /* round to previous (or same iff dir == RoundDownMaybe) */
-
-               uint32_t difference = ticks % ticks_one_subdivisions_worth;
-
-               if (difference == 0 && dir == RoundDownAlways) {
-                       /* right on the subdivision, but force-rounding down,
-                          so the difference is just the subdivision ticks */
-                       difference = ticks_one_subdivisions_worth;
-               }
-
-               if (ticks < difference) {
-                       ticks = BBT_Time::ticks_per_beat - ticks;
-               } else {
-                       ticks -= difference;
-               }
-
-       } else {
-               /* round to nearest */
-               double rem;
-
-               /* compute the distance to the previous and next subdivision */
-
-               if ((rem = fmod ((double) ticks, (double) ticks_one_subdivisions_worth)) > ticks_one_subdivisions_worth/2.0) {
-
-                       /* closer to the next subdivision, so shift forward */
-
-                       ticks = lrint (ticks + (ticks_one_subdivisions_worth - rem));
-
-                       DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("moved forward to %1\n", ticks));
-
-                       if (ticks > BBT_Time::ticks_per_beat) {
-                               ++beats;
-                               ticks -= BBT_Time::ticks_per_beat;
-                               DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("fold beat to %1\n", beats));
-                       }
-
-               } else if (rem > 0) {
-
-                       /* closer to previous subdivision, so shift backward */
-
-                       if (rem > ticks) {
-                               if (beats == 0) {
-                                       /* can't go backwards past zero, so ... */
-                                       return 0;
-                               }
-                               /* step back to previous beat */
-                               --beats;
-                               ticks = lrint (BBT_Time::ticks_per_beat - rem);
-                               DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("step back beat to %1\n", beats));
-                       } else {
-                               ticks = lrint (ticks - rem);
-                               DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("moved backward to %1\n", ticks));
-                       }
-               } else {
-                       /* on the subdivision, do nothing */
-               }
-       }
-
-       const framepos_t ret_frame = frame_at_minute (minute_at_beat_locked (_metrics, beats + (ticks / BBT_Time::ticks_per_beat)));
-
-       return ret_frame;
-}
-
-framepos_t
+MusicFrame
 TempoMap::round_to_quarter_note_subdivision (framepos_t fr, int sub_num, RoundMode dir)
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
-       uint32_t ticks = (uint32_t) floor (max (0.0, quarter_note_at_minute_locked (_metrics, minute_at_frame (fr))) * BBT_Time::ticks_per_beat);
+       uint32_t ticks = (uint32_t) floor (max (0.0, pulse_at_minute_locked (_metrics, minute_at_frame (fr))) * BBT_Time::ticks_per_beat * 4.0);
        uint32_t beats = (uint32_t) floor (ticks / BBT_Time::ticks_per_beat);
        uint32_t ticks_one_subdivisions_worth = (uint32_t) BBT_Time::ticks_per_beat / sub_num;
 
@@ -3873,7 +4040,7 @@ TempoMap::round_to_quarter_note_subdivision (framepos_t fr, int sub_num, RoundMo
                        if (rem > ticks) {
                                if (beats == 0) {
                                        /* can't go backwards past zero, so ... */
-                                       return 0;
+                                       return MusicFrame (0, 0);
                                }
                                /* step back to previous beat */
                                --beats;
@@ -3888,35 +4055,46 @@ TempoMap::round_to_quarter_note_subdivision (framepos_t fr, int sub_num, RoundMo
                }
        }
 
-       const framepos_t ret_frame = frame_at_minute (minute_at_quarter_note_locked (_metrics, beats + (ticks / BBT_Time::ticks_per_beat)));
+       MusicFrame ret (0, 0);
+       ret.frame = frame_at_minute (minute_at_pulse_locked (_metrics, (beats + (ticks / BBT_Time::ticks_per_beat)) / 4.0));
+       ret.division = sub_num;
 
-       return ret_frame;
+       return ret;
 }
 
-framepos_t
+MusicFrame
 TempoMap::round_to_type (framepos_t frame, RoundMode dir, BBTPointType type)
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
-
-       const double beat_at_framepos = max (0.0, beat_at_minute_locked (_metrics, minute_at_frame (frame)));
+       const double minute = minute_at_frame (frame);
+       const double beat_at_framepos = max (0.0, beat_at_minute_locked (_metrics, minute));
        BBT_Time bbt (bbt_at_beat_locked (_metrics, beat_at_framepos));
+       MusicFrame ret (0, 0);
 
        switch (type) {
        case Bar:
+               ret.division = -1;
+
                if (dir < 0) {
                        /* find bar previous to 'frame' */
                        if (bbt.bars > 0)
                                --bbt.bars;
                        bbt.beats = 1;
                        bbt.ticks = 0;
-                       return frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
+
+                       ret.frame = frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
+
+                       return ret;
 
                } else if (dir > 0) {
                        /* find bar following 'frame' */
                        ++bbt.bars;
                        bbt.beats = 1;
                        bbt.ticks = 0;
-                       return frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
+
+                       ret.frame = frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
+
+                       return ret;
                } else {
                        /* true rounding: find nearest bar */
                        framepos_t raw_ft = frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
@@ -3927,26 +4105,39 @@ TempoMap::round_to_type (framepos_t frame, RoundMode dir, BBTPointType type)
                        framepos_t next_ft = frame_at_minute (minute_at_bbt_locked (_metrics, bbt));
 
                        if ((raw_ft - prev_ft) > (next_ft - prev_ft) / 2) {
-                               return next_ft;
+                               ret.frame = next_ft;
+
+                               return ret;
                        } else {
-                               return prev_ft;
+                               --bbt.bars;
+                               ret.frame = prev_ft;
+
+                               return ret;
                        }
                }
 
                break;
 
        case Beat:
+               ret.division = 1;
+
                if (dir < 0) {
-                       return frame_at_minute (minute_at_beat_locked (_metrics, floor (beat_at_framepos)));
+                       ret.frame = frame_at_minute (minute_at_beat_locked (_metrics, floor (beat_at_framepos)));
+
+                       return ret;
                } else if (dir > 0) {
-                       return frame_at_minute (minute_at_beat_locked (_metrics, ceil (beat_at_framepos)));
+                       ret.frame = frame_at_minute (minute_at_beat_locked (_metrics, ceil (beat_at_framepos)));
+
+                       return ret;
                } else {
-                       return frame_at_minute (minute_at_beat_locked (_metrics, floor (beat_at_framepos + 0.5)));
+                       ret.frame = frame_at_minute (minute_at_beat_locked (_metrics, floor (beat_at_framepos + 0.5)));
+
+                       return ret;
                }
                break;
        }
 
-       return 0;
+       return MusicFrame (0, 0);
 }
 
 void
@@ -4079,6 +4270,11 @@ TempoMap::tempo_section_at_beat_locked (const Metrics& metrics, const double& be
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                if ((*i)->is_tempo()) {
                        t = static_cast<TempoSection*> (*i);
+
+                       if (!t->active()) {
+                               continue;
+                       }
+
                        if (prev_t && ((t->pulse() - prev_m->pulse()) * prev_m->note_divisor()) + prev_m->beat() > beat) {
                                break;
                        }
@@ -4089,6 +4285,42 @@ TempoMap::tempo_section_at_beat_locked (const Metrics& metrics, const double& be
        return *prev_t;
 }
 
+TempoSection*
+TempoMap::next_tempo_section (TempoSection* ts) const
+{
+       if (!ts) {
+               return 0;
+       }
+
+       Glib::Threads::RWLock::ReaderLock lm (lock);
+
+       TempoSection* prev = 0;
+
+       for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
+
+               if ((*i)->is_tempo()) {
+                       TempoSection* t = static_cast<TempoSection*> (*i);
+
+                       if (!t->active()) {
+                               continue;
+                       }
+
+                       if (prev && prev == ts) {
+
+                               return t;
+                       }
+
+                       prev = t;
+               }
+       }
+
+       if (prev == 0) {
+               fatal << endmsg;
+               abort(); /*NOTREACHED*/
+       }
+
+       return 0;
+}
 /* don't use this to calculate length (the tempo is only correct for this frame).
    do that stuff based on the beat_at_frame and frame_at_beat api
 */
@@ -4199,6 +4431,7 @@ TempoMap::fix_legacy_session ()
 {
        MeterSection* prev_m = 0;
        TempoSection* prev_t = 0;
+       bool have_initial_t = false;
 
        for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
                MeterSection* m;
@@ -4237,10 +4470,21 @@ TempoMap::fix_legacy_session ()
                                t->set_minute (0.0);
                                t->set_position_lock_style (AudioTime);
                                prev_t = t;
+                               have_initial_t = true;
                                continue;
                        }
 
                        if (prev_t) {
+                               /* some 4.x sessions have no initial (non-movable) tempo. */
+                               if (!have_initial_t) {
+                                       prev_t->set_pulse (0.0);
+                                       prev_t->set_minute (0.0);
+                                       prev_t->set_position_lock_style (AudioTime);
+                                       prev_t->set_initial (true);
+                                       prev_t->set_locked_to_meter (true);
+                                       have_initial_t = true;
+                               }
+
                                const double beat = ((t->legacy_bbt().bars - 1) * ((prev_m) ? prev_m->note_divisor() : 4.0))
                                        + (t->legacy_bbt().beats - 1)
                                        + (t->legacy_bbt().ticks / BBT_Time::ticks_per_beat);
@@ -4255,6 +4499,30 @@ TempoMap::fix_legacy_session ()
                }
        }
 }
+void
+TempoMap::fix_legacy_end_session ()
+{
+       TempoSection* prev_t = 0;
+
+       for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
+               TempoSection* t;
+
+               if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
+
+                       if (!t->active()) {
+                               continue;
+                       }
+
+                       if (prev_t) {
+                               if (prev_t->type() != TempoSection::Constant) {
+                                       prev_t->set_end_note_types_per_minute (t->note_types_per_minute());
+                               }
+                       }
+
+                       prev_t = t;
+               }
+       }
+}
 
 XMLNode&
 TempoMap::get_state ()
@@ -4331,6 +4599,12 @@ TempoMap::set_state (const XMLNode& node, int /*version*/)
                                        fix_legacy_session();
                                        break;
                                }
+
+                               if (t->legacy_end()) {
+                                       fix_legacy_end_session();
+                                       break;
+                               }
+
                                break;
                        }
                }
@@ -4389,19 +4663,20 @@ TempoMap::dump (std::ostream& o) const
        for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
 
                if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
-                       o << "Tempo @ " << *i << t->note_types_per_minute() << " BPM (pulse = 1/" << t->note_type()
+                       o << "Tempo @ " << *i << " start : " << t->note_types_per_minute() << " end : " << t->end_note_types_per_minute() << " BPM (pulse = 1/" << t->note_type()
                          << " type= " << enum_2_string (t->type()) << ") "  << " at pulse= " << t->pulse()
                          << " minute= " << t->minute() << " frame= " << t->frame() << " (initial? " << t->initial() << ')'
                          << " pos lock: " << enum_2_string (t->position_lock_style()) << std::endl;
                        if (prev_t) {
-                               o <<  "  current      : " << t->note_types_per_minute()
+                               o <<  "  current start  : " << t->note_types_per_minute()
+                                 <<  "  current end  : " << t->end_note_types_per_minute()
                                  << " | " << t->pulse() << " | " << t->frame() << " | " << t->minute() << std::endl;
                                o << "  previous     : " << prev_t->note_types_per_minute()
                                  << " | " << prev_t->pulse() << " | " << prev_t->frame() << " | " << prev_t->minute() << std::endl;
                                o << "  calculated   : " << prev_t->tempo_at_pulse (t->pulse())
-                                 << " | " << prev_t->pulse_at_ntpm (t->note_types_per_minute(), t->minute())
-                                 << " | " << frame_at_minute (prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()))
-                                 << " | " << prev_t->minute_at_ntpm (t->note_types_per_minute(), t->pulse()) << std::endl;
+                                 << " | " << prev_t->pulse_at_ntpm (prev_t->end_note_types_per_minute(), t->minute())
+                                 << " | " << frame_at_minute (prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()))
+                                 << " | " << prev_t->minute_at_ntpm (prev_t->end_note_types_per_minute(), t->pulse()) << std::endl;
                        }
                        prev_t = t;
                } else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
@@ -4532,9 +4807,9 @@ framepos_t
 TempoMap::framepos_plus_qn (framepos_t frame, Evoral::Beats beats) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
-       const double frame_qn = quarter_note_at_minute_locked (_metrics, minute_at_frame (frame));
+       const double frame_qn = pulse_at_minute_locked (_metrics, minute_at_frame (frame)) * 4.0;
 
-       return frame_at_minute (minute_at_quarter_note_locked (_metrics, frame_qn + beats.to_double()));
+       return frame_at_minute (minute_at_pulse_locked (_metrics, (frame_qn + beats.to_double()) / 4.0));
 }
 
 framepos_t