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tempo.cc

/*
    Copyright (C) 2000-2002 Paul Davis 

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <algorithm>
#include <unistd.h>

#include <cmath>

#include <sigc++/bind.h>

#include <glibmm/thread.h>
#include <pbd/xml++.h>
#include <ardour/tempo.h>
#include <ardour/utils.h>

#include "i18n.h"
#include <locale.h>

using namespace std;
using namespace ARDOUR;
using namespace PBD;

/* _default tempo is 4/4 qtr=120 */

Meter    TempoMap::_default_meter (4.0, 4.0);
Tempo    TempoMap::_default_tempo (120.0);

const double Meter::ticks_per_beat = 1920.0;

double Tempo::frames_per_beat (nframes_t sr, const Meter& meter) const
{
      return  ((60.0 * sr) / (_beats_per_minute * meter.note_divisor()/_note_type));
}

/***********************************************************************/

double
Meter::frames_per_bar (const Tempo& tempo, nframes_t sr) const
{
      return ((60.0 * sr * _beats_per_bar) / (tempo.beats_per_minute() * _note_type/tempo.note_type()));
}

/***********************************************************************/

const string TempoSection::xml_state_node_name = "Tempo";

TempoSection::TempoSection (const XMLNode& node)
      : MetricSection (BBT_Time()), Tempo (TempoMap::default_tempo())
{
      const XMLProperty *prop;
      BBT_Time start;
      LocaleGuard lg (X_("POSIX"));

      if ((prop = node.property ("start")) == 0) {
            error << _("TempoSection XML node has no \"start\" property") << endmsg;
            throw failed_constructor();
      }

      if (sscanf (prop->value().c_str(), "%" PRIu32 "|%" PRIu32 "|%" PRIu32,
                &start.bars,
                &start.beats,
                &start.ticks) < 3) {
            error << _("TempoSection XML node has an illegal \"start\" value") << endmsg;
            throw failed_constructor();
      }

      set_start (start);

      if ((prop = node.property ("beats-per-minute")) == 0) {
            error << _("TempoSection XML node has no \"beats-per-minute\" property") << endmsg;
            throw failed_constructor();
      }

      if (sscanf (prop->value().c_str(), "%lf", &_beats_per_minute) != 1 || _beats_per_minute < 0.0) {
            error << _("TempoSection XML node has an illegal \"beats_per_minute\" value") << endmsg;
            throw failed_constructor();
      }
      
      if ((prop = node.property ("note-type")) == 0) {
            /* older session, make note type be quarter by default */
            _note_type = 4.0;
      } else {
            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();
            }
      }

      if ((prop = node.property ("movable")) == 0) {
            error << _("TempoSection XML node has no \"movable\" property") << endmsg;
            throw failed_constructor();
      }

      set_movable (prop->value() == "yes");
}

XMLNode&
TempoSection::get_state() const
{
      XMLNode *root = new XMLNode (xml_state_node_name);
      char buf[256];
      LocaleGuard lg (X_("POSIX"));

      snprintf (buf, sizeof (buf), "%" PRIu32 "|%" PRIu32 "|%" PRIu32, 
              start().bars,
              start().beats,
              start().ticks);
      root->add_property ("start", buf);
      snprintf (buf, sizeof (buf), "%f", _beats_per_minute);
      root->add_property ("beats-per-minute", buf);
      snprintf (buf, sizeof (buf), "%f", _note_type);
      root->add_property ("note-type", buf);
      snprintf (buf, sizeof (buf), "%s", movable()?"yes":"no");
      root->add_property ("movable", buf);

      return *root;
}

/***********************************************************************/

const string MeterSection::xml_state_node_name = "Meter";

MeterSection::MeterSection (const XMLNode& node)
      : MetricSection (BBT_Time()), Meter (TempoMap::default_meter())
{
      const XMLProperty *prop;
      BBT_Time start;
      LocaleGuard lg (X_("POSIX"));

      if ((prop = node.property ("start")) == 0) {
            error << _("MeterSection XML node has no \"start\" property") << endmsg;
            throw failed_constructor();
      }

      if (sscanf (prop->value().c_str(), "%" PRIu32 "|%" PRIu32 "|%" PRIu32,
                &start.bars,
                &start.beats,
                &start.ticks) < 3) {
            error << _("MeterSection XML node has an illegal \"start\" value") << endmsg;
            throw failed_constructor();
      }

      set_start (start);

      if ((prop = node.property ("beats-per-bar")) == 0) {
            error << _("MeterSection XML node has no \"beats-per-bar\" property") << endmsg;
            throw failed_constructor();
      }

      if (sscanf (prop->value().c_str(), "%lf", &_beats_per_bar) != 1 || _beats_per_bar < 0.0) {
            error << _("MeterSection XML node has an illegal \"beats-per-bar\" value") << endmsg;
            throw failed_constructor();
      }

      if ((prop = node.property ("note-type")) == 0) {
            error << _("MeterSection XML node has no \"note-type\" property") << endmsg;
            throw failed_constructor();
      }
      
      if (sscanf (prop->value().c_str(), "%lf", &_note_type) != 1 || _note_type < 0.0) {
            error << _("MeterSection XML node has an illegal \"note-type\" value") << endmsg;
            throw failed_constructor();
      }

      if ((prop = node.property ("movable")) == 0) {
            error << _("MeterSection XML node has no \"movable\" property") << endmsg;
            throw failed_constructor();
      }

      set_movable (prop->value() == "yes");
}

XMLNode&
MeterSection::get_state() const
{
      XMLNode *root = new XMLNode (xml_state_node_name);
      char buf[256];
      LocaleGuard lg (X_("POSIX"));

      snprintf (buf, sizeof (buf), "%" PRIu32 "|%" PRIu32 "|%" PRIu32, 
              start().bars,
              start().beats,
              start().ticks);
      root->add_property ("start", buf);
      snprintf (buf, sizeof (buf), "%f", _note_type);
      root->add_property ("note-type", buf);
      snprintf (buf, sizeof (buf), "%f", _beats_per_bar);
      root->add_property ("beats-per-bar", buf);
      snprintf (buf, sizeof (buf), "%s", movable()?"yes":"no");
      root->add_property ("movable", buf);

      return *root;
}

/***********************************************************************/

struct MetricSectionSorter {
    bool operator() (const MetricSection* a, const MetricSection* b) {
          return a->start() < b->start();
    }
};

TempoMap::TempoMap (nframes_t fr)
{
      metrics = new Metrics;
      _frame_rate = fr;
      last_bbt_valid = false;
      BBT_Time start;
      
      start.bars = 1;
      start.beats = 1;
      start.ticks = 0;

      TempoSection *t = new TempoSection (start, _default_tempo.beats_per_minute(), _default_tempo.note_type());
      MeterSection *m = new MeterSection (start, _default_meter.beats_per_bar(), _default_meter.note_divisor());

      t->set_movable (false);
      m->set_movable (false);

      /* note: frame time is correct (zero) for both of these */
      
      metrics->push_back (t);
      metrics->push_back (m);
}

TempoMap::~TempoMap ()
{
}

int
TempoMap::move_metric_section (MetricSection& section, const BBT_Time& when)
{
      if (when == section.start() || !section.movable()) {
            return -1;
      }

      Glib::RWLock::WriterLock  lm (lock);
      MetricSectionSorter cmp;

      if (when.beats != 1) {

            /* position by audio frame, then recompute BBT timestamps from the audio ones */

            nframes_t frame = frame_time (when);
            // cerr << "nominal frame time = " << frame << endl;

            nframes_t prev_frame = round_to_type (frame, -1, Beat);
            nframes_t next_frame = round_to_type (frame, 1, Beat);
            
            // cerr << "previous beat at " << prev_frame << " next at " << next_frame << endl;

            /* use the closest beat */

            if ((frame - prev_frame) < (next_frame - frame)) {
                  frame = prev_frame;
            } else {
                  frame = next_frame;
            }
            
            // cerr << "actual frame time = " << frame << endl;
            section.set_frame (frame);
            // cerr << "frame time = " << section.frame() << endl;
            timestamp_metrics (false);
            // cerr << "new BBT time = " << section.start() << endl;
            metrics->sort (cmp);

      } else {

            /* positioned at bar start already, so just put it there */

            section.set_start (when);
            metrics->sort (cmp);
            timestamp_metrics (true);
      }


      return 0;
}

void
TempoMap::move_tempo (TempoSection& tempo, const BBT_Time& when)
{
      if (move_metric_section (tempo, when) == 0) {
            StateChanged (Change (0));
      }
}

void
TempoMap::move_meter (MeterSection& meter, const BBT_Time& when)
{
      if (move_metric_section (meter, when) == 0) {
            StateChanged (Change (0));
      }
}

void
TempoMap::remove_tempo (const TempoSection& tempo)
{
      bool removed = false;

      {
            Glib::RWLock::WriterLock lm (lock);
            Metrics::iterator i;

            for (i = metrics->begin(); i != metrics->end(); ++i) {
                  if (dynamic_cast<TempoSection*> (*i) != 0) {
                        if (tempo.frame() == (*i)->frame()) {
                              if ((*i)->movable()) {
                                    metrics->erase (i);
                                    removed = true;
                                    break;
                              }
                        }
                  }
            }
      }

      if (removed) {
            StateChanged (Change (0));
      }
}

void
TempoMap::remove_meter (const MeterSection& tempo)
{
      bool removed = false;

      {
            Glib::RWLock::WriterLock lm (lock);
            Metrics::iterator i;

            for (i = metrics->begin(); i != metrics->end(); ++i) {
                  if (dynamic_cast<MeterSection*> (*i) != 0) {
                        if (tempo.frame() == (*i)->frame()) {
                              if ((*i)->movable()) {
                                    metrics->erase (i);
                                    removed = true;
                                    break;
                              }
                        }
                  }
            }
      }

      if (removed) {
            StateChanged (Change (0));
      }
}

void
TempoMap::do_insert (MetricSection* section, bool with_bbt)
{
      Metrics::iterator i;

      for (i = metrics->begin(); i != metrics->end(); ++i) {
            
            if (with_bbt) {
                  if ((*i)->start() < section->start()) {
                        continue;
                  }
            } else {
                  if ((*i)->frame() < section->frame()) {
                        continue;
                  }                 
            }

            metrics->insert (i, section);
            break;
      }
      
      if (i == metrics->end()) {
            metrics->insert (metrics->end(), section);
      }
      
      timestamp_metrics (with_bbt);
}     

void
TempoMap::add_tempo (const Tempo& tempo, BBT_Time where)
{
      {
            Glib::RWLock::WriterLock lm (lock);

            /* new tempos always start on a beat */
      
            where.ticks = 0;
            
            do_insert (new TempoSection (where, tempo.beats_per_minute(), tempo.note_type()), true);
      }

      StateChanged (Change (0));
}

void
TempoMap::add_tempo (const Tempo& tempo, nframes_t where)
{
      {
            Glib::RWLock::WriterLock lm (lock);
            do_insert (new TempoSection (where, tempo.beats_per_minute(), tempo.note_type()), false);
      }

      StateChanged (Change (0));
}

void
TempoMap::replace_tempo (TempoSection& existing, const Tempo& replacement)
{
      bool replaced = false;

      { 
            Glib::RWLock::WriterLock lm (lock);
            Metrics::iterator i;
            
            for (i = metrics->begin(); i != metrics->end(); ++i) {
                  TempoSection *ts;

                  if ((ts = dynamic_cast<TempoSection*>(*i)) != 0 && ts == &existing) {

                         *((Tempo *) ts) = replacement;

                        replaced = true;
                        timestamp_metrics (true);

                        break;
                  }
            }
      }
      
      if (replaced) {
            StateChanged (Change (0));
      }
}

void
TempoMap::add_meter (const Meter& meter, BBT_Time where)
{
      {
            Glib::RWLock::WriterLock lm (lock);

            /* a new meter always starts a new bar on the first beat. so
               round the start time appropriately. remember that
               `where' is based on the existing tempo map, not
               the result after we insert the new meter.

            */

            if (where.beats != 1) {
                  where.beats = 1;
                  where.bars++;
            }

            /* new meters *always* start on a beat. */
            
            where.ticks = 0;

            do_insert (new MeterSection (where, meter.beats_per_bar(), meter.note_divisor()), true);
      }

      StateChanged (Change (0));
}

void
TempoMap::add_meter (const Meter& meter, nframes_t where)
{
      {
            Glib::RWLock::WriterLock lm (lock);
            do_insert (new MeterSection (where, meter.beats_per_bar(), meter.note_divisor()), false);
      }

      StateChanged (Change (0));
}

void
TempoMap::replace_meter (MeterSection& existing, const Meter& replacement)
{
      bool replaced = false;

      { 
            Glib::RWLock::WriterLock lm (lock);
            Metrics::iterator i;
            
            for (i = metrics->begin(); i != metrics->end(); ++i) {
                  MeterSection *ms;
                  if ((ms = dynamic_cast<MeterSection*>(*i)) != 0 && ms == &existing) {
                        
                        *((Meter*) ms) = replacement;

                        replaced = true;
                        timestamp_metrics (true);
                        break;
                  }
            }
      }
      
      if (replaced) {
            StateChanged (Change (0));
      }
}

void
TempoMap::change_initial_tempo (double beats_per_minute, double note_type)
{
      Tempo newtempo (beats_per_minute, note_type);
      TempoSection* t;

      for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
            if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
                  *((Tempo*) t) = newtempo;
                  StateChanged (Change (0));
                  break;
            }
      }
}

void
TempoMap::change_existing_tempo_at (nframes_t where, double beats_per_minute, double note_type)
{
      Tempo newtempo (beats_per_minute, note_type);

      TempoSection* prev;
      TempoSection* first;
      Metrics::iterator i;

      /* find the TempoSection immediately preceding "where"
       */

      for (first = 0, i = metrics->begin(), prev = 0; i != metrics->end(); ++i) {

            if ((*i)->frame() > where) {
                  break;
            }

            TempoSection* t;

            if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
                  if (!first) {
                        first = t;
                  }
                  prev = t;
            }
      }

      if (!prev) {
            if (!first) {
                  error << string_compose (_("no tempo sections defined in tempo map - cannot change tempo @ %1"), where) << endmsg;
                  return;
            }

            prev = first;
      }

      /* reset */

      *((Tempo*)prev) = newtempo;
      StateChanged (Change (0));
}

const MeterSection&
TempoMap::first_meter () const
{
      const MeterSection *m = 0;

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
            if ((m = dynamic_cast<const MeterSection *> (*i)) != 0) {
                  return *m;
            }
      }

      fatal << _("programming error: no tempo section in tempo map!") << endmsg;
      /*NOTREACHED*/
      return *m;
}

const TempoSection&
TempoMap::first_tempo () const
{
      const TempoSection *t = 0;

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
            if ((t = dynamic_cast<const TempoSection *> (*i)) != 0) {
                  return *t;
            }
      }

      fatal << _("programming error: no tempo section in tempo map!") << endmsg;
      /*NOTREACHED*/
      return *t;
}

void
TempoMap::timestamp_metrics (bool use_bbt)
{
      Metrics::iterator i;
      const Meter* meter;
      const Tempo* tempo;
      Meter *m;
      Tempo *t;

      meter = &first_meter ();
      tempo = &first_tempo ();

      if (use_bbt) {

            // cerr << "\n\n\n ######################\nTIMESTAMP via BBT ##############\n" << endl;

            nframes_t current = 0;
            nframes_t section_frames;
            BBT_Time start;
            BBT_Time end;

            for (i = metrics->begin(); i != metrics->end(); ++i) {
                  
                  end = (*i)->start();
                  
                  section_frames = count_frames_between_metrics (*meter, *tempo, start, end);
                  
                  current += section_frames;
                  
                  start = end;
                  
                  (*i)->set_frame (current);
                  
                  if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
                        tempo = t;
                  } else if ((m = dynamic_cast<MeterSection*>(*i)) != 0) {
                        meter = m;
                  } else {
                        fatal << _("programming error: unhandled MetricSection type") << endmsg;
                        /*NOTREACHED*/
                  }
            }

      } else {

            // cerr << "\n\n\n ######################\nTIMESTAMP via AUDIO ##############\n" << endl;

            bool first = true;
            MetricSection* prev = 0;

            for (i = metrics->begin(); i != metrics->end(); ++i) {

                  BBT_Time bbt;
                  Metric metric (*meter, *tempo);
                  
                  if (prev) {
                        metric.set_start (prev->start());
                  } else {
                        // metric will be at frames=0 bbt=1|1|0 by default
                        // which is correct for our purpose
                  }
            
                  bbt_time_with_metric ((*i)->frame(), bbt, metric);

                  // cerr << "timestamp @ " << (*i)->frame() << " with " << bbt.bars << "|" << bbt.beats << "|" << bbt.ticks << " => ";
                  

                  if (first) {
                        first = false;
                  } else {
                        
                        if (bbt.ticks > Meter::ticks_per_beat/2) {
                              /* round up to next beat */
                              bbt.beats += 1;
                        } 

                        bbt.ticks = 0;

                        if (bbt.beats != 1) {
                              /* round up to next bar */
                              bbt.bars += 1;
                              bbt.beats = 1;
                        }
                  }
                  
                  //s cerr << bbt.bars << "|" << bbt.beats << "|" << bbt.ticks << endl;
                  
                  (*i)->set_start (bbt);

                  if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
                        tempo = t;
                        // cerr << "NEW TEMPO, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
                  } else if ((m = dynamic_cast<MeterSection*>(*i)) != 0) {
                        meter = m;
                        // cerr << "NEW METER, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
                  } else {
                        fatal << _("programming error: unhandled MetricSection type") << endmsg;
                        /*NOTREACHED*/
                  }

                  prev = (*i);
            }
      }

      // dump (cerr);
      // cerr << "###############################################\n\n\n" << endl;

}

TempoMap::Metric
TempoMap::metric_at (nframes_t frame) const
{
      Metric m (first_meter(), first_tempo());
      const Meter* meter;
      const Tempo* tempo;

      /* at this point, we are *guaranteed* to have m.meter and m.tempo pointing
         at something, because we insert the default tempo and meter during
         TempoMap construction.

         now see if we can find better candidates.
      */

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {

            if ((*i)->frame() > frame) {
                  break;
            }

            if ((tempo = dynamic_cast<const TempoSection*>(*i)) != 0) {
                  m.set_tempo (*tempo);
            } else if ((meter = dynamic_cast<const MeterSection*>(*i)) != 0) {
                  m.set_meter (*meter);
            }

            m.set_frame ((*i)->frame ());
            m.set_start ((*i)->start ());
      }
      
      return m;
}

TempoMap::Metric
TempoMap::metric_at (BBT_Time bbt) const
{
      Metric m (first_meter(), first_tempo());
      const Meter* meter;
      const Tempo* tempo;

      /* at this point, we are *guaranteed* to have m.meter and m.tempo pointing
         at something, because we insert the default tempo and meter during
         TempoMap construction.

         now see if we can find better candidates.
      */

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {

            BBT_Time section_start ((*i)->start());

            if (section_start.bars > bbt.bars || (section_start.bars == bbt.bars && section_start.beats > bbt.beats)) {
                  break;
            }

            if ((tempo = dynamic_cast<const TempoSection*>(*i)) != 0) {
                  m.set_tempo (*tempo);
            } else if ((meter = dynamic_cast<const MeterSection*>(*i)) != 0) {
                  m.set_meter (*meter);
            }
            
            m.set_frame ((*i)->frame ());
            m.set_start (section_start);
      }

      return m;
}

void
TempoMap::bbt_time (nframes_t frame, BBT_Time& bbt) const
{
        {
              Glib::RWLock::ReaderLock lm (lock);
            bbt_time_unlocked (frame, bbt);
      }
}

void
TempoMap::bbt_time_unlocked (nframes_t frame, BBT_Time& bbt) const
{
      bbt_time_with_metric (frame, bbt, metric_at (frame));
}

void
TempoMap::bbt_time_with_metric (nframes_t frame, BBT_Time& bbt, const Metric& metric) const
{
      nframes_t frame_diff;

      uint32_t xtra_bars = 0;
      double xtra_beats = 0;
      double beats = 0;

      // cerr << "---- BBT time for " << frame << " using metric @ " << metric.frame() << " BBT " << metric.start() << endl;

      const double beats_per_bar = metric.meter().beats_per_bar();
      const double frames_per_bar = metric.meter().frames_per_bar (metric.tempo(), _frame_rate);
      const double beat_frames = metric.tempo().frames_per_beat (_frame_rate, metric.meter());

      /* now compute how far beyond that point we actually are. */

      frame_diff = frame - metric.frame();
      
      // cerr << "----\tdelta = " << frame_diff << endl;

      xtra_bars = (uint32_t) floor (frame_diff / frames_per_bar);
      frame_diff -= (uint32_t) floor (xtra_bars * frames_per_bar);
      xtra_beats = (double) frame_diff / beat_frames;

      // cerr << "---\tmeaning " << xtra_bars << " xtra bars and " << xtra_beats << " xtra beats\n";

      /* and set the returned value */

      /* and correct beat/bar shifts to match the meter.
        remember: beat and bar counting is 1-based, 
        not zero-based 
        also the meter may contain a fraction
      */
      
      bbt.bars = metric.start().bars + xtra_bars; 

      beats = (double) metric.start().beats + xtra_beats;
      
      bbt.bars += (uint32_t) floor(beats/ (beats_per_bar+1) );

      beats = fmod(beats - 1, beats_per_bar )+ 1.0;
      bbt.ticks = (uint32_t)( round((beats - floor(beats)) *(double) Meter::ticks_per_beat));
      bbt.beats = (uint32_t) floor(beats);
      
      // cerr << "-----\t RETURN " << bbt << endl;
}

nframes_t 
TempoMap::count_frames_between ( const BBT_Time& start, const BBT_Time& end) const
{
        /* for this to work with fractional measure types, start and end have to be "legal" BBT types, 
         that means that the beats and ticks should be inside a bar
      */

      nframes_t frames = 0;
      nframes_t start_frame = 0;
      nframes_t end_frame = 0;

      Metric m = metric_at (start);

      uint32_t bar_offset = start.bars - m.start().bars;

      double  beat_offset = bar_offset*m.meter().beats_per_bar() - (m.start().beats-1) + (start.beats -1) 
            + start.ticks/Meter::ticks_per_beat;


      start_frame = m.frame() + (nframes_t) rint( beat_offset * m.tempo().frames_per_beat(_frame_rate, m.meter()));

      m =  metric_at(end);

      bar_offset = end.bars - m.start().bars;

      beat_offset = bar_offset * m.meter().beats_per_bar() - (m.start().beats -1) + (end.beats - 1) 
            + end.ticks/Meter::ticks_per_beat;

      end_frame = m.frame() + (nframes_t) rint(beat_offset * m.tempo().frames_per_beat(_frame_rate, m.meter()));

      frames = end_frame - start_frame;

      return frames;
      
}     

nframes_t 
TempoMap::count_frames_between_metrics (const Meter& meter, const Tempo& tempo, const BBT_Time& start, const BBT_Time& end) const
{
        /* this is used in timestamping the metrics by actually counting the beats */ 

      nframes_t frames = 0;
      uint32_t bar = start.bars;
      double beat = (double) start.beats;
      double beats_counted = 0;
      double beats_per_bar = 0;
      double beat_frames = 0;

      beats_per_bar = meter.beats_per_bar();
      beat_frames = tempo.frames_per_beat (_frame_rate,meter);

      frames = 0;

      while (bar < end.bars || (bar == end.bars && beat < end.beats)) {
            
            if (beat >= beats_per_bar) {
                  beat = 1;
                  ++bar;
                  ++beats_counted;

                  if (beat > beats_per_bar) {

                        /* this is a fractional beat at the end of a fractional bar
                           so it should only count for the fraction 
                        */

                        beats_counted -= (ceil(beats_per_bar) - beats_per_bar);
                  }

            } else {
                  ++beat;
                  ++beats_counted;
            }
      }

      // cerr << "Counted " << beats_counted << " from " << start << " to " << end 
      // << " bpb were " << beats_per_bar 
      // << " fpb was " << beat_frames
      // << endl;
      
      frames = (nframes_t) floor (beats_counted * beat_frames);

      return frames;
      
}     

nframes_t 
TempoMap::frame_time (const BBT_Time& bbt) const
{
      BBT_Time start ; /* 1|1|0 */

      return  count_frames_between ( start, bbt);
}

nframes_t 
TempoMap::bbt_duration_at (nframes_t pos, const BBT_Time& bbt, int dir) const
{
      nframes_t frames = 0;

      BBT_Time when;
      bbt_time(pos,when);

      {
            Glib::RWLock::ReaderLock lm (lock);
            frames = bbt_duration_at_unlocked (when, bbt,dir);
      }

      return frames;
}

nframes_t 
TempoMap::bbt_duration_at_unlocked (const BBT_Time& when, const BBT_Time& bbt, int dir) const
{

      nframes_t frames = 0;

      double beats_per_bar;
      BBT_Time result;
      
      result.bars = max(1U,when.bars + dir * bbt.bars) ;
      result.beats = 1;
      result.ticks = 0;

      Metric      metric = metric_at(result);
      beats_per_bar = metric.meter().beats_per_bar();



        /*reduce things to legal bbt  values 
        we have to handle possible fractional=shorter beats at the end of measures
          and things like 0|11|9000  as a duration in a 4.5/4 measure
        the musical decision is that the fractional beat is also a beat , although a shorter one 
      */

    
      if (dir >= 0) {
            result.beats = when.beats +  bbt.beats;
            result.ticks = when.ticks +  bbt.ticks;

            while (result.beats >= (beats_per_bar+1)) {
                  result.bars++;
                  result.beats -=  (uint32_t) ceil(beats_per_bar);
                  metric = metric_at(result); // maybe there is a meter change
                  beats_per_bar = metric.meter().beats_per_bar();
                  
            }
            /*we now counted the beats and landed in the target measure, now deal with ticks 
              this seems complicated, but we want to deal with the corner case of a sequence of time signatures like 0.2/4-0.7/4
              and with request like bbt = 3|2|9000 ,so we repeat the same loop but add ticks
            */

            /* of course gtk_ardour only allows bar with at least 1.0 beats .....
             */

            uint32_t ticks_at_beat = (uint32_t) ( result.beats == ceil(beats_per_bar) ?
                              (1 - (ceil(beats_per_bar) - beats_per_bar))* Meter::ticks_per_beat 
                                 : Meter::ticks_per_beat );

            while (result.ticks >= ticks_at_beat) {
                  result.beats++;
                  result.ticks -= ticks_at_beat;
                  if  (result.beats >= (beats_per_bar+1)) {
                        result.bars++;
                        result.beats = 1;
                        metric = metric_at(result); // maybe there is a meter change
                        beats_per_bar = metric.meter().beats_per_bar();
                  }
                  ticks_at_beat= (uint32_t) ( result.beats == ceil(beats_per_bar) ?
                               (1 - (ceil(beats_per_bar) - beats_per_bar) )* Meter::ticks_per_beat 
                               : Meter::ticks_per_beat);

            }

        
      } else {
            uint32_t b = bbt.beats;

                /* count beats */
            while( b > when.beats ) {
                  
                  result.bars = max(1U,result.bars-- ) ;
                  metric = metric_at(result); // maybe there is a meter change
                  beats_per_bar = metric.meter().beats_per_bar();
                  if (b >= ceil(beats_per_bar)) {
                        
                        b -= (uint32_t) ceil(beats_per_bar);
                  } else {
                        b = (uint32_t) ceil(beats_per_bar)- b + when.beats ;
                  }
            }
            result.beats = when.beats - b;
                
                /*count ticks */

            if (bbt.ticks <= when.ticks) {
                  result.ticks = when.ticks - bbt.ticks;
            } else {

                  uint32_t ticks_at_beat= (uint32_t) Meter::ticks_per_beat;
                  uint32_t t = bbt.ticks - when.ticks;

                  do {

                        if (result.beats == 1) {
                              result.bars = max(1U,result.bars-- ) ;
                              metric = metric_at(result); // maybe there is a meter change
                              beats_per_bar = metric.meter().beats_per_bar();
                              result.beats = (uint32_t) ceil(beats_per_bar);
                              ticks_at_beat = (uint32_t) ((1 - (ceil(beats_per_bar) - beats_per_bar))* Meter::ticks_per_beat) ;
                        } else {
                              result.beats --;
                              ticks_at_beat = (uint32_t) Meter::ticks_per_beat;
                        }
                                    
                        if (t <= ticks_at_beat) {
                              result.ticks = ticks_at_beat - t; 
                        } else {
                              t-= ticks_at_beat;
                        }
                  } while (t > ticks_at_beat);

            }


      }

      if (dir < 0 ) {
            frames = count_frames_between( result,when);
      } else {
            frames = count_frames_between(when,result);
      }

      return frames;
}



nframes_t
TempoMap::round_to_bar (nframes_t fr, int dir)
{
        {
              Glib::RWLock::ReaderLock lm (lock);
            return round_to_type (fr, dir, Bar);
      }
}


nframes_t
TempoMap::round_to_beat (nframes_t fr, int dir)
{
        {
              Glib::RWLock::ReaderLock lm (lock);
            return round_to_type (fr, dir, Beat);
      }
}

nframes_t

TempoMap::round_to_beat_subdivision (nframes_t fr, int sub_num)
{

      BBT_Time the_beat;
      uint32_t ticks_one_half_subdivisions_worth;
      uint32_t ticks_one_subdivisions_worth;

      bbt_time(fr, the_beat);

      ticks_one_subdivisions_worth = (uint32_t)Meter::ticks_per_beat / sub_num;
      ticks_one_half_subdivisions_worth = ticks_one_subdivisions_worth / 2;

      if (the_beat.ticks % ticks_one_subdivisions_worth > ticks_one_half_subdivisions_worth) {
        uint32_t difference = ticks_one_subdivisions_worth - (the_beat.ticks % ticks_one_subdivisions_worth);
        if (the_beat.ticks + difference >= (uint32_t)Meter::ticks_per_beat) {
          the_beat.beats++;
          the_beat.ticks += difference;
          the_beat.ticks -= (uint32_t)Meter::ticks_per_beat;
        } else {  
          the_beat.ticks += difference;
        }
      } else {
        the_beat.ticks -= the_beat.ticks % ticks_one_subdivisions_worth;
      }

      return frame_time (the_beat);
}

nframes_t
TempoMap::round_to_type (nframes_t frame, int dir, BBTPointType type)
{
      Metric metric = metric_at (frame);
      BBT_Time bbt;
      BBT_Time start;
      bbt_time_with_metric (frame, bbt, metric);

      switch (type) {
      case Bar:
            if (dir < 0) {
                  /* relax */

            } else if (dir > 0) {
                  if (bbt.beats > 0) {
                        bbt.bars++;
                  }
            } else {
                  if (bbt.beats > metric.meter().beats_per_bar()/2) {
                        bbt.bars++;
                  }

            }
            bbt.beats = 1;
            bbt.ticks = 0;
            break;
      
      case Beat:
            if (dir < 0) {
                  /* relax */
            } else if (dir > 0) {
                  if (bbt.ticks > 0) {
                        bbt.beats++;
                  }
            } else {
                  if (bbt.ticks >= (Meter::ticks_per_beat/2)) {
                        bbt.beats++;
                  }
            }
            if (bbt.beats > ceil(metric.meter().beats_per_bar()) ) {
                  bbt.beats = 1;
                  bbt.bars++;
            }
            bbt.ticks = 0;
            break;
      
      }

      /* 
         cerr << "for " << frame << " round to " << bbt << " using "
         << metric.start()
         << endl;
      */

      return metric.frame() + count_frames_between (metric.start(), bbt);
}

TempoMap::BBTPointList *
TempoMap::get_points (nframes_t lower, nframes_t upper) const
{

      Metrics::const_iterator i;
      BBTPointList *points;
      double current;
      const MeterSection* meter;
      const MeterSection* m;
      const TempoSection* tempo;
      const TempoSection* t;
      uint32_t bar;
      uint32_t beat;
      double beats_per_bar;
      double beat_frame;
      double beat_frames;
      double frames_per_bar;
      double delta_bars;
      double delta_beats;
      double dummy;
      nframes_t limit;

      meter = &first_meter ();
      tempo = &first_tempo ();

      /* find the starting point */

      for (i = metrics->begin(); i != metrics->end(); ++i) {

            if ((*i)->frame() > lower) {
                  break;
            }

            if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
                  tempo = t;
            } else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
                  meter = m;
            }
      }

      /* We now have:
         
         meter -> the Meter for "lower"
         tempo -> the Tempo for "lower"
         i     -> for first new metric after "lower", possibly metrics->end()

         Now start generating points.
      */

      beats_per_bar = meter->beats_per_bar ();
      frames_per_bar = meter->frames_per_bar (*tempo, _frame_rate);
      beat_frames = tempo->frames_per_beat (_frame_rate, *meter);
      
      if (meter->frame() > tempo->frame()) {
            bar = meter->start().bars;
            beat = meter->start().beats;
            current = meter->frame();
      } else {
            bar = tempo->start().bars;
            beat = tempo->start().beats;
            current = tempo->frame();
      }

      /* initialize current to point to the bar/beat just prior to the
         lower frame bound passed in.  assumes that current is initialized
         above to be on a beat.
      */
      
      delta_bars = (lower-current) / frames_per_bar;
      delta_beats = modf(delta_bars, &dummy) * beats_per_bar;
      current += (floor(delta_bars) * frames_per_bar) +  (floor(delta_beats) * beat_frames);

      // adjust bars and beats too
      bar += (uint32_t) (floor(delta_bars));
      beat += (uint32_t) (floor(delta_beats));

      points = new BBTPointList;
            
      do {

            if (i == metrics->end()) {
                  limit = upper;
                  // cerr << "== limit set to end of request @ " << limit << endl;
            } else {
                  // cerr << "== limit set to next metric @ " << (*i)->frame() << endl;
                  limit = (*i)->frame();
            }

            limit = min (limit, upper);

            while (current < limit) {
                  
                  /* if we're at the start of a bar, add bar point */

                  if (beat == 1) {
                        if (current >= lower) {
                              // cerr << "Add Bar at " << bar << "|1" << " @ " << current << endl;
                              points->push_back (BBTPoint (*meter, *tempo,(nframes_t)rint(current), Bar, bar, 1));

                        }
                  }

                  /* add some beats if we can */

                  beat_frame = current;

                  while (beat <= ceil( beats_per_bar) && beat_frame < limit) {
                        if (beat_frame >= lower) {
                              // cerr << "Add Beat at " << bar << '|' << beat << " @ " << beat_frame << endl;
                              points->push_back (BBTPoint (*meter, *tempo, (nframes_t) rint(beat_frame), Beat, bar, beat));
                        }
                        beat_frame += beat_frames;
                        current+= beat_frames;
                         
                        beat++;
                  }

                  //  cerr << "out of beats, @ end ? " << (i == metrics->end()) << " out of bpb ? "
                  // << (beat > ceil(beats_per_bar))
                  // << endl;

                  if (beat > ceil(beats_per_bar) || i != metrics->end()) {

                        /* we walked an entire bar. its
                           important to move `current' forward
                           by the actual frames_per_bar, not move it to
                           an integral beat_frame, so that metrics with
                           non-integral beats-per-bar have
                           their bar positions set
                           correctly. consider a metric with
                           9-1/2 beats-per-bar. the bar we
                           just filled had  10 beat marks,
                           but the bar end is 1/2 beat before
                           the last beat mark.
                           And it is also possible that a tempo 
                           change occured in the middle of a bar, 
                           so we subtract the possible extra fraction from the current
                        */

                        if (beat > ceil (beats_per_bar)) {
                              /* next bar goes where the numbers suggest */
                              current -=  beat_frames * (ceil(beats_per_bar)-beats_per_bar);
                              // cerr << "++ next bar from numbers\n";
                        } else {
                              /* next bar goes where the next metric is */
                              current = limit;
                              // cerr << "++ next bar at next metric\n";
                        }
                        bar++;
                        beat = 1;
                  } 
            
            }

            /* if we're done, then we're done */

            if (current >= upper) {
                  break;
            }

            /* i is an iterator that refers to the next metric (or none).
               if there is a next metric, move to it, and continue.
            */

            if (i != metrics->end()) {

                  if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
                        tempo = t;
                  } else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
                        meter = m;
                        /* new MeterSection, beat always returns to 1 */
                        beat = 1;
                  }

                  current = (*i)->frame ();
                  // cerr << "loop around with current @ " << current << endl;

                  beats_per_bar = meter->beats_per_bar ();
                  frames_per_bar = meter->frames_per_bar (*tempo, _frame_rate);
                  beat_frames = tempo->frames_per_beat (_frame_rate, *meter);
                  
                  ++i;
            }

      } while (1);

      return points;
}     

const TempoSection&
TempoMap::tempo_section_at (nframes_t frame)
{
      Glib::RWLock::ReaderLock lm (lock);
      Metrics::iterator i;
      TempoSection* prev = 0;
      
      for (i = metrics->begin(); i != metrics->end(); ++i) {
            TempoSection* t;

            if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {

                  if ((*i)->frame() > frame) {
                        break;
                  }

                  prev = t;
            }
      }

      if (prev == 0) {
            fatal << endmsg;
      }

      return *prev;
}

const Tempo&
TempoMap::tempo_at (nframes_t frame)
{
      Metric m (metric_at (frame));
      return m.tempo();
}


const Meter&
TempoMap::meter_at (nframes_t frame)
{
      Metric m (metric_at (frame));
      return m.meter();
}

XMLNode&
TempoMap::get_state ()
{
      Metrics::const_iterator i;
      XMLNode *root = new XMLNode ("TempoMap");

      {
                Glib::RWLock::ReaderLock lm (lock);
            for (i = metrics->begin(); i != metrics->end(); ++i) {
                    root->add_child_nocopy ((*i)->get_state());
            }
      }

      return *root;
}

int
TempoMap::set_state (const XMLNode& node)
{
      {
            Glib::RWLock::WriterLock lm (lock);

            XMLNodeList nlist;
            XMLNodeConstIterator niter;
            Metrics old_metrics (*metrics);
            
            metrics->clear();

            nlist = node.children();
            
            for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
                  XMLNode* child = *niter;
                  
                  if (child->name() == TempoSection::xml_state_node_name) {
                        
                        try {
                              metrics->push_back (new TempoSection (*child));
                        }
                        
                        catch (failed_constructor& err){
                              error << _("Tempo map: could not set new state, restoring old one.") << endmsg;
                              *metrics = old_metrics;
                              break;
                        }
                        
                  } else if (child->name() == MeterSection::xml_state_node_name) {
                        
                        try {
                              metrics->push_back (new MeterSection (*child));
                        }
                        
                        catch (failed_constructor& err) {
                              error << _("Tempo map: could not set new state, restoring old one.") << endmsg;
                              *metrics = old_metrics;
                              break;
                        }
                  }
            }
            
            if (niter == nlist.end()) {
                  
                  MetricSectionSorter cmp;
                  metrics->sort (cmp);
                  timestamp_metrics (true);
            }
      }
      
      StateChanged (Change (0));

      return 0;
}

void
TempoMap::dump (std::ostream& o) const
{
      const MeterSection* m;
      const TempoSection* t;
      
      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {

            if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
                  o << "Tempo @ " << *i << ' ' << t->beats_per_minute() << " BPM (denom = " << t->note_type() << ") at " << t->start() << " frame= " << t->frame() << " (move? "
                    << t->movable() << ')' << endl;
            } else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
                  o << "Meter @ " << *i << ' ' << m->beats_per_bar() << '/' << m->note_divisor() << " at " << m->start() << " frame= " << m->frame() 
                    << " (move? " << m->movable() << ')' << endl;
            }
      }
}

int
TempoMap::n_tempos() const
{
      Glib::RWLock::ReaderLock lm (lock);
      int cnt = 0;

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
            if (dynamic_cast<const TempoSection*>(*i) != 0) {
                  cnt++;
            }
      }

      return cnt;
}

int
TempoMap::n_meters() const
{
      Glib::RWLock::ReaderLock lm (lock);
      int cnt = 0;

      for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
            if (dynamic_cast<const MeterSection*>(*i) != 0) {
                  cnt++;
            }
      }

      return cnt;
}

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