Avoid the use of dynamic_cast in TempoMap for performance improvement.

	- review / comment would be appreciated here.

diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index 1bf4c47d7a29e8998b6a37d2afe8ee8241330cc0..45fbfe44a7a4b682cd689e417b5d409e688cfaa9 100644 (file)
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -105,8 +105,8 @@ class LIBARDOUR_API Meter {
 /** A section of timeline with a certain Tempo or Meter. */
 class LIBARDOUR_API MetricSection {
   public:
-       MetricSection (double pulse, framepos_t frame, PositionLockStyle pls)
-               : _pulse (pulse), _frame (frame), _movable (true), _position_lock_style (pls) {}
+       MetricSection (double pulse, framepos_t frame, PositionLockStyle pls, bool is_tempo)
+               : _pulse (pulse), _frame (frame), _movable (true), _position_lock_style (pls), _is_tempo (is_tempo) {}
 
        virtual ~MetricSection() {}
 
@@ -129,19 +129,21 @@ class LIBARDOUR_API MetricSection {
 
        PositionLockStyle position_lock_style () const { return _position_lock_style; }
        void set_position_lock_style (PositionLockStyle ps) { _position_lock_style = ps; }
+       const bool is_tempo () const { return _is_tempo; }
 
 private:
        double             _pulse;
        framepos_t         _frame;
        bool               _movable;
        PositionLockStyle  _position_lock_style;
+       const bool         _is_tempo;
 };
 
 /** A section of timeline with a certain Meter. */
 class LIBARDOUR_API MeterSection : public MetricSection, public Meter {
   public:
        MeterSection (double pulse, framepos_t frame, double beat, const Timecode::BBT_Time& bbt, double bpb, double note_type, PositionLockStyle pls)
-               : MetricSection (pulse, frame, pls), Meter (bpb, note_type), _bbt (bbt),  _beat (beat) {}
+               : MetricSection (pulse, frame, pls, false), Meter (bpb, note_type), _bbt (bbt),  _beat (beat) {}
 
        MeterSection (const XMLNode&);
 
@@ -172,7 +174,7 @@ class LIBARDOUR_API TempoSection : public MetricSection, public Tempo {
        };
 
        TempoSection (const double& pulse, const framepos_t& frame, double qpm, double note_type, Type tempo_type, PositionLockStyle pls)
-               : MetricSection (pulse, frame, pls), Tempo (qpm, note_type), _type (tempo_type), _c_func (0.0), _active (true), _locked_to_meter (false)  {}
+               : MetricSection (pulse, frame, pls, true), Tempo (qpm, note_type), _type (tempo_type), _c_func (0.0), _active (true), _locked_to_meter (false)  {}
 
        TempoSection (const XMLNode&);
 
@@ -198,8 +200,8 @@ class LIBARDOUR_API TempoSection : public MetricSection, public Tempo {
        double tempo_at_pulse (const double& pulse) const;
        double pulse_at_tempo (const double& ppm, const framepos_t& frame, const framecnt_t& frame_rate) const;
 
-       double pulse_at_frame (const framepos_t& frame, const framecnt_t& frame_rate) const;
-       frameoffset_t frame_at_pulse (const double& pulse, const framecnt_t& frame_rate) const;
+       double pulse_at_frame (const framepos_t& frame, const framepos_t& frame_rate) const;
+       framepos_t frame_at_pulse (const double& pulse, const framecnt_t& frame_rate) const;
 
        double compute_c_func_pulse (const double& end_bpm, const double& end_pulse, const framecnt_t& frame_rate);
        double compute_c_func_frame (const double& end_bpm, const framepos_t& end_frame, const framecnt_t& frame_rate) const;
@@ -401,7 +403,7 @@ class LIBARDOUR_API TempoMap : public PBD::StatefulDestructible
        */
 
        double beat_at_frame (const framecnt_t& frame) const;
-       framecnt_t frame_at_beat (const double& beat) const;
+       framepos_t frame_at_beat (const double& beat) const;
 
        Tempo tempo_at_frame (const framepos_t& frame) const;
        framepos_t frame_at_tempo (const Tempo& tempo) const;
@@ -415,7 +417,7 @@ class LIBARDOUR_API TempoMap : public PBD::StatefulDestructible
        double beat_at_pulse (const double& pulse) const;
 
        double pulse_at_frame (const framecnt_t& frame) const;
-       framecnt_t frame_at_pulse (const double& pulse) const;
+       framepos_t frame_at_pulse (const double& pulse) const;
 
        /* bbt - it's nearly always better to use beats.*/
        Timecode::BBT_Time bbt_at_frame (framepos_t when);
@@ -461,13 +463,13 @@ class LIBARDOUR_API TempoMap : public PBD::StatefulDestructible
 private:
 
        double beat_at_frame_locked (const Metrics& metrics, const framecnt_t& frame) const;
-       framecnt_t frame_at_beat_locked (const Metrics& metrics, const double& beat) const;
+       framepos_t frame_at_beat_locked (const Metrics& metrics, const double& beat) const;
 
        double pulse_at_beat_locked (const Metrics& metrics, const double& beat) const;
        double beat_at_pulse_locked (const Metrics& metrics, const double& pulse) const;
 
-       double pulse_at_frame_locked (const Metrics& metrics, const framecnt_t& frame) const;
-       framecnt_t frame_at_pulse_locked (const Metrics& metrics, const double& pulse) const;
+       double pulse_at_frame_locked (const Metrics& metrics, const framepos_t& frame) const;
+       framepos_t frame_at_pulse_locked (const Metrics& metrics, const double& pulse) const;
 
        Tempo tempo_at_frame_locked (const Metrics& metrics, const framepos_t& frame) const;
        framepos_t frame_at_tempo_locked (const Metrics& metrics, const Tempo& tempo) const;

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index e0aeae3809d22375da5503ffcba383c1c9a06b23..cc423ef4a5b71488931c9c3e12a0aa272c9c4efb 100644 (file)
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -73,7 +73,7 @@ Meter::frames_per_bar (const Tempo& tempo, framecnt_t sr) const
 const string TempoSection::xml_state_node_name = "Tempo";
 
 TempoSection::TempoSection (const XMLNode& node)
-       : MetricSection (0.0, 0, MusicTime)
+       : MetricSection (0.0, 0, MusicTime, true)
        , Tempo (TempoMap::default_tempo())
        , _c_func (0.0)
        , _active (true)
@@ -453,7 +453,7 @@ TempoSection::time_at_pulse (const double& pulse) const
 const string MeterSection::xml_state_node_name = "Meter";
 
 MeterSection::MeterSection (const XMLNode& node)
-       : MetricSection (0.0, 0, MusicTime), Meter (TempoMap::default_meter())
+       : MetricSection (0.0, 0, MusicTime, false), Meter (TempoMap::default_meter())
 {
        XMLProperty const * prop;
        LocaleGuard lg;
@@ -1231,7 +1231,8 @@ TempoMap::recompute_tempos (Metrics& metrics)
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
 
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -1273,14 +1274,16 @@ TempoMap::recompute_meters (Metrics& metrics)
        MeterSection* prev_m = 0;
 
        for (Metrics::const_iterator mi = metrics.begin(); mi != metrics.end(); ++mi) {
-               if ((meter = dynamic_cast<MeterSection*> (*mi)) != 0) {
+               if (!(*mi)->is_tempo()) {
+                       meter = static_cast<MeterSection*> (*mi);
                        if (meter->position_lock_style() == AudioTime) {
                                double pulse = 0.0;
                                pair<double, BBT_Time> b_bbt;
                                TempoSection* meter_locked_tempo = 0;
                                for (Metrics::const_iterator ii = metrics.begin(); ii != metrics.end(); ++ii) {
                                        TempoSection* t;
-                                       if ((t = dynamic_cast<TempoSection*> (*ii)) != 0) {
+                                       if ((*ii)->is_tempo()) {
+                                               t = static_cast<TempoSection*> (*ii);
                                                if ((t->locked_to_meter() || !t->movable()) && t->frame() == meter->frame()) {
                                                        meter_locked_tempo = t;
                                                        break;
@@ -1410,7 +1413,8 @@ TempoMap::metric_at (BBT_Time bbt) const
 
        for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
                MeterSection* mw;
-               if ((mw = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       mw = static_cast<MeterSection*> (*i);
                        BBT_Time section_start (mw->bbt());
 
                        if (section_start.bars > bbt.bars || (section_start.bars == bbt.bars && section_start.beats > bbt.beats)) {
@@ -1440,13 +1444,12 @@ TempoMap::beat_at_frame_locked (const Metrics& metrics, const framecnt_t& frame)
        MeterSection* next_m = 0;
 
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
-                       if (prev_m && m->frame() > frame) {
-                               next_m = m;
+               if (!(*i)->is_tempo()) {
+                       if (prev_m && (*i)->frame() > frame) {
+                               next_m = static_cast<MeterSection*> (*i);
                                break;
                        }
-                       prev_m = m;
+                       prev_m = static_cast<MeterSection*> (*i);
                }
        }
        if (frame < prev_m->frame()) {
@@ -1462,7 +1465,7 @@ TempoMap::beat_at_frame_locked (const Metrics& metrics, const framecnt_t& frame)
        return beat;
 }
 
-framecnt_t
+framepos_t
 TempoMap::frame_at_beat (const double& beat) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
@@ -1470,15 +1473,17 @@ TempoMap::frame_at_beat (const double& beat) const
 }
 
 /* meter & tempo section based */
-framecnt_t
+framepos_t
 TempoMap::frame_at_beat_locked (const Metrics& metrics, const double& beat) const
 {
        MeterSection* prev_m = 0;
        TempoSection* prev_t = 0;
 
+       MeterSection* m;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m && m->beat() > beat) {
                                break;
                        }
@@ -1486,9 +1491,11 @@ TempoMap::frame_at_beat_locked (const Metrics& metrics, const double& beat) cons
                }
        }
 
+       TempoSection* t;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (prev_t && ((t->pulse() - prev_m->pulse()) * prev_m->note_divisor()) + prev_m->beat() > beat) {
                                break;
                        }
@@ -1512,9 +1519,11 @@ TempoMap::tempo_at_frame_locked (const Metrics& metrics, const framepos_t& frame
 {
        TempoSection* prev_t = 0;
 
+       TempoSection* t;
+
        for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
-               TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -1557,7 +1566,8 @@ TempoMap::frame_at_tempo_locked (const Metrics& metrics, const Tempo& tempo) con
 
        for (i = _metrics.begin(); i != _metrics.end(); ++i) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
 
                        if (!t->active()) {
                                continue;
@@ -1573,8 +1583,7 @@ TempoMap::frame_at_tempo_locked (const Metrics& metrics, const Tempo& tempo) con
                                const double prev_t_ppm = prev_t->beats_per_minute() / prev_t->note_type();
 
                                if ((t_ppm > tempo_ppm && prev_t_ppm < tempo_ppm) || (t_ppm < tempo_ppm && prev_t_ppm > tempo_ppm)) {
-                                       const framepos_t ret_frame = prev_t->frame_at_tempo (tempo_ppm, prev_t->pulse(), _frame_rate);
-                                       return ret_frame;
+                                       return prev_t->frame_at_tempo (tempo_ppm, prev_t->pulse(), _frame_rate);
                                }
                        }
                        prev_t = t;
@@ -1627,7 +1636,8 @@ TempoMap::beat_at_pulse_locked (const Metrics& metrics, const double& pulse) con
 
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m && m->pulse() > pulse) {
                                if (((pulse - prev_m->pulse()) * prev_m->note_divisor()) + prev_m->beat() > m->beat()) {
                                        break;
@@ -1642,7 +1652,7 @@ TempoMap::beat_at_pulse_locked (const Metrics& metrics, const double& pulse) con
 }
 
 double
-TempoMap::pulse_at_frame (const framecnt_t& frame) const
+TempoMap::pulse_at_frame (const framepos_t& frame) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
        return pulse_at_frame_locked (_metrics, frame);
@@ -1650,14 +1660,15 @@ TempoMap::pulse_at_frame (const framecnt_t& frame) const
 
 /* tempo section based */
 double
-TempoMap::pulse_at_frame_locked (const Metrics& metrics, const framecnt_t& frame) const
+TempoMap::pulse_at_frame_locked (const Metrics& metrics, const framepos_t& frame) const
 {
        /* HOLD (at least) THE READER LOCK */
        TempoSection* prev_t = 0;
 
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -1676,7 +1687,7 @@ TempoMap::pulse_at_frame_locked (const Metrics& metrics, const framecnt_t& frame
        return pulses_in_section + prev_t->pulse();
 }
 
-framecnt_t
+framepos_t
 TempoMap::frame_at_pulse (const double& pulse) const
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
@@ -1684,7 +1695,7 @@ TempoMap::frame_at_pulse (const double& pulse) const
 }
 
 /* tempo section based */
-framecnt_t
+framepos_t
 TempoMap::frame_at_pulse_locked (const Metrics& metrics, const double& pulse) const
 {
        /* HOLD THE READER LOCK */
@@ -1694,7 +1705,8 @@ TempoMap::frame_at_pulse_locked (const Metrics& metrics, const double& pulse) co
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
 
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -1706,12 +1718,9 @@ TempoMap::frame_at_pulse_locked (const Metrics& metrics, const double& pulse) co
                }
        }
        /* must be treated as constant, irrespective of _type */
-       double const pulses_in_section = pulse - prev_t->pulse();
-       double const dtime = pulses_in_section * prev_t->frames_per_pulse (_frame_rate);
+       double const dtime = (pulse - prev_t->pulse()) * prev_t->frames_per_pulse (_frame_rate);
 
-       framecnt_t const ret = (framecnt_t) floor (dtime) + prev_t->frame();
-
-       return ret;
+       return (framecnt_t) floor (dtime) + prev_t->frame();
 }
 
 double
@@ -1732,9 +1741,11 @@ TempoMap::beat_at_bbt_locked (const Metrics& metrics, const Timecode::BBT_Time&
        /* because audio-locked meters have 'fake' integral beats,
           there is no pulse offset here.
        */
+       MeterSection* m;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m) {
                                const double bars_to_m = (m->beat() - prev_m->beat()) / prev_m->divisions_per_bar();
                                if ((bars_to_m + (prev_m->bbt().bars - 1)) > (bbt.bars - 1)) {
@@ -1766,10 +1777,11 @@ TempoMap::bbt_at_beat_locked (const Metrics& metrics, const double& b) const
        MeterSection* prev_m = 0;
        const double beats = max (0.0, b);
 
-       for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m = 0;
+       MeterSection* m = 0;
 
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+       for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m) {
                                if (m->beat() > beats) {
                                        /* this is the meter after the one our beat is on*/
@@ -1828,9 +1840,11 @@ TempoMap::pulse_at_bbt_locked (const Metrics& metrics, const Timecode::BBT_Time&
        /* because audio-locked meters have 'fake' integral beats,
           there is no pulse offset here.
        */
+       MeterSection* m;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m) {
                                if (m->bbt().bars > bbt.bars) {
                                        break;
@@ -1860,10 +1874,12 @@ TempoMap::bbt_at_pulse_locked (const Metrics& metrics, const double& pulse) cons
 {
        MeterSection* prev_m = 0;
 
+       MeterSection* m = 0;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m = 0;
 
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
 
                        if (prev_m) {
                                double const pulses_to_m = m->pulse() - prev_m->pulse();
@@ -1950,9 +1966,11 @@ TempoMap::bbt_at_frame_locked (const Metrics& metrics, const framepos_t& frame)
        MeterSection* prev_m = 0;
        MeterSection* next_m = 0;
 
+       MeterSection* m;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m && m->frame() > frame) {
                                next_m = m;
                                break;
@@ -2038,7 +2056,8 @@ TempoMap::check_solved (const Metrics& metrics) const
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
                MeterSection* m;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -2066,9 +2085,10 @@ TempoMap::check_solved (const Metrics& metrics) const
                        prev_t = t;
                }
 
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m && m->position_lock_style() == AudioTime) {
-                               TempoSection* t = const_cast<TempoSection*>(&tempo_section_at_frame_locked (metrics, m->frame() - 1));
+                               const TempoSection* t = &tempo_section_at_frame_locked (metrics, m->frame() - 1);
                                const double nascent_m_pulse = ((m->beat() - prev_m->beat()) / prev_m->note_divisor()) + prev_m->pulse();
                                const framepos_t nascent_m_frame = t->frame_at_pulse (nascent_m_pulse, _frame_rate);
 
@@ -2090,7 +2110,8 @@ TempoMap::set_active_tempos (const Metrics& metrics, const framepos_t& frame)
 {
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->movable()) {
                                t->set_active (true);
                                continue;
@@ -2118,7 +2139,8 @@ TempoMap::solve_map_frame (Metrics& imaginary, TempoSection* section, const fram
        /* can't move a tempo before the first meter */
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (!m->movable()) {
                                first_m_frame = m->frame();
                                break;
@@ -2134,7 +2156,8 @@ TempoMap::solve_map_frame (Metrics& imaginary, TempoSection* section, const fram
 
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
 
                        if (!t->active()) {
                                continue;
@@ -2200,7 +2223,8 @@ TempoMap::solve_map_pulse (Metrics& imaginary, TempoSection* section, const doub
 
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -2284,7 +2308,8 @@ TempoMap::solve_map_frame (Metrics& imaginary, MeterSection* section, const fram
 
        for (Metrics::const_iterator ii = imaginary.begin(); ii != imaginary.end(); ++ii) {
                TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*ii)) != 0) {
+               if ((*ii)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*ii);
                        if ((t->locked_to_meter() || !t->movable()) && t->frame() == section->frame()) {
                                meter_locked_tempo = t;
                                break;
@@ -2303,7 +2328,8 @@ TempoMap::solve_map_frame (Metrics& imaginary, MeterSection* section, const fram
 
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (m == section){
                                if (prev_m && section->movable()) {
                                        const double beats = (pulse_at_frame_locked (imaginary, frame) - prev_m->pulse()) * prev_m->note_divisor();
@@ -2412,7 +2438,8 @@ TempoMap::solve_map_bbt (Metrics& imaginary, MeterSection* section, const BBT_Ti
        /* disallow setting section to an existing meter's bbt */
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (m != section && m->bbt().bars == when.bars) {
                                return false;
                        }
@@ -2424,7 +2451,8 @@ TempoMap::solve_map_bbt (Metrics& imaginary, MeterSection* section, const BBT_Ti
 
        for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        pair<double, BBT_Time> b_bbt;
                        double new_pulse = 0.0;
 
@@ -2446,7 +2474,8 @@ TempoMap::solve_map_bbt (Metrics& imaginary, MeterSection* section, const BBT_Ti
 
                                for (Metrics::const_iterator ii = imaginary.begin(); ii != imaginary.end(); ++ii) {
                                        TempoSection* t;
-                                       if ((t = dynamic_cast<TempoSection*> (*ii)) != 0) {
+                                       if ((*i)->is_tempo()) {
+                                               t = static_cast<TempoSection*> (*ii);
                                                if ((t->locked_to_meter() || !t->movable()) && t->frame() == m->frame()) {
                                                        meter_locked_tempo = t;
                                                        break;
@@ -2529,7 +2558,8 @@ TempoMap::copy_metrics_and_point (const Metrics& metrics, Metrics& copy, TempoSe
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
                MeterSection* m;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (t == section) {
                                ret = new TempoSection (*t);
                                copy.push_back (ret);
@@ -2539,7 +2569,8 @@ TempoMap::copy_metrics_and_point (const Metrics& metrics, Metrics& copy, TempoSe
                        TempoSection* cp = new TempoSection (*t);
                        copy.push_back (cp);
                }
-               if ((m = dynamic_cast<MeterSection *> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection *> (*i);
                        MeterSection* cp = new MeterSection (*m);
                        copy.push_back (cp);
                }
@@ -2556,12 +2587,14 @@ TempoMap::copy_metrics_and_point (const Metrics& metrics, Metrics& copy, MeterSe
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                TempoSection* t;
                MeterSection* m;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        TempoSection* cp = new TempoSection (*t);
                        copy.push_back (cp);
                }
 
-               if ((m = dynamic_cast<MeterSection *> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection *> (*i);
                        if (m == section) {
                                ret = new MeterSection (*m);
                                copy.push_back (ret);
@@ -2794,7 +2827,8 @@ TempoMap::gui_dilate_tempo (TempoSection* ts, const framepos_t& frame, const fra
                TempoSection* next_t = 0;
                for (Metrics::iterator i = future_map.begin(); i != future_map.end(); ++i) {
                        TempoSection* t = 0;
-                       if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+                       if ((*i)->is_tempo()) {
+                               t = static_cast<TempoSection*> (*i);
                                if (t->frame() > ts->frame()) {
                                        next_t = t;
                                        break;
@@ -3147,13 +3181,14 @@ TempoMap::tempo_section_at_frame (framepos_t frame) const
 const TempoSection&
 TempoMap::tempo_section_at_frame_locked (const Metrics& metrics, framepos_t frame) const
 {
-       Metrics::const_iterator i;
        TempoSection* prev = 0;
 
-       for (i = metrics.begin(); i != metrics.end(); ++i) {
-               TempoSection* t;
+       TempoSection* t;
 
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+       for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
+
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
@@ -3179,9 +3214,11 @@ TempoMap::tempo_section_at_beat_locked (const Metrics& metrics, const double& be
        TempoSection* prev_t = 0;
        const MeterSection* prev_m = &meter_section_at_beat_locked (metrics, beat);
 
+       TempoSection* t;
+
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
-               TempoSection* t;
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (prev_t && ((t->pulse() - prev_m->pulse()) * prev_m->note_divisor()) + prev_m->beat() > beat) {
                                break;
                        }
@@ -3200,21 +3237,23 @@ TempoMap::frames_per_beat_at (const framepos_t& frame, const framecnt_t& sr) con
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
 
-       const TempoSection* ts_at = &tempo_section_at_frame_locked (_metrics, frame);
+       const TempoSection* ts_at = 0;
        const TempoSection* ts_after = 0;
        Metrics::const_iterator i;
+       TempoSection* t;
 
        for (i = _metrics.begin(); i != _metrics.end(); ++i) {
-               TempoSection* t;
 
-               if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
+               if ((*i)->is_tempo()) {
+                       t = static_cast<TempoSection*> (*i);
                        if (!t->active()) {
                                continue;
                        }
-                       if ((*i)->frame() > frame) {
+                       if (ts_at && (*i)->frame() > frame) {
                                ts_after = t;
                                break;
                        }
+                       ts_at = t;
                }
        }
 
@@ -3231,10 +3270,12 @@ TempoMap::meter_section_at_frame_locked (const Metrics& metrics, framepos_t fram
        Metrics::const_iterator i;
        MeterSection* prev = 0;
 
+       MeterSection* m;
+
        for (i = metrics.begin(); i != metrics.end(); ++i) {
-               MeterSection* m;
 
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
 
                        if (prev && (*i)->frame() > frame) {
                                break;
@@ -3267,7 +3308,8 @@ TempoMap::meter_section_at_beat_locked (const Metrics& metrics, const double& be
 
        for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
                MeterSection* m;
-               if ((m = dynamic_cast<MeterSection*> (*i)) != 0) {
+               if (!(*i)->is_tempo()) {
+                       m = static_cast<MeterSection*> (*i);
                        if (prev_m && m->beat() > beat) {
                                break;
                        }
@@ -3501,7 +3543,7 @@ TempoMap::n_tempos() const
        int cnt = 0;
 
        for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
-               if (dynamic_cast<const TempoSection*>(*i) != 0) {
+               if ((*i)->is_tempo()) {
                        cnt++;
                }
        }
@@ -3516,7 +3558,7 @@ TempoMap::n_meters() const
        int cnt = 0;
 
        for (Metrics::const_iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
-               if (dynamic_cast<const MeterSection*>(*i) != 0) {
+               if (!(*i)->is_tempo()) {
                        cnt++;
                }
        }