libs/ardour/midi_clock_slave.cc

   1 /*
   2     Copyright (C) 2008 Paul Davis
   3     Author: Hans Baier
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19 */
  20
  21 #include <cmath>
  22 #include <errno.h>
  23 #include <poll.h>
  24 #include <sys/types.h>
  25 #include <unistd.h>
  26 #include "pbd/error.h"
  27 #include "pbd/failed_constructor.h"
  28 #include "pbd/pthread_utils.h"
  29
  30 #include "midi++/port.h"
  31 #include "midi++/jack.h"
  32
  33 #include "ardour/debug.h"
  34 #include "ardour/slave.h"
  35 #include "ardour/session.h"
  36 #include "ardour/audioengine.h"
  37 #include "ardour/cycles.h"
  38 #include "ardour/tempo.h"
  39
  40
  41 #include "i18n.h"
  42
  43 using namespace std;
  44 using namespace ARDOUR;
  45 using namespace MIDI;
  46 using namespace PBD;
  47
  48 #define DEBUG_MIDI_CLOCK 1
  49
  50 MIDIClock_Slave::MIDIClock_Slave (Session& s, MIDI::Port& p, int ppqn)
  51         : ppqn (ppqn)
  52         , bandwidth (1.0 / 60.0) // 1 BpM = 1 / 60 Hz
  53 {
  54         session = (ISlaveSessionProxy *) new SlaveSessionProxy(s);
  55         rebind (p);
  56         reset ();
  57 }
  58
  59 MIDIClock_Slave::MIDIClock_Slave (ISlaveSessionProxy* session_proxy, int ppqn)
  60         : session(session_proxy)
  61         , ppqn (ppqn)
  62         , bandwidth (1.0 / 60.0) // 1 BpM = 1 / 60 Hz
  63 {
  64         reset ();
  65 }
  66
  67 MIDIClock_Slave::~MIDIClock_Slave()
  68 {
  69         delete session;
  70 }
  71
  72 void
  73 MIDIClock_Slave::rebind (MIDI::Port& p)
  74 {
  75         port_connections.drop_connections();
  76
  77         port = &p;
  78
  79         DEBUG_TRACE (DEBUG::MidiClock, string_compose ("MIDIClock_Slave: connecting to port %1\n", port->name()));
  80
  81         port->input()->timing.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::update_midi_clock, this, _1, _2));
  82         port->input()->start.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::start, this, _1, _2));
  83         port->input()->contineu.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::contineu, this, _1, _2));
  84         port->input()->stop.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::stop, this, _1, _2));
  85         port->input()->position.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::position, this, _1, _2, 3));
  86 }
  87
  88 void
  89 MIDIClock_Slave::calculate_one_ppqn_in_frames_at(nframes64_t time)
  90 {
  91         const Tempo& current_tempo = session->tempo_map().tempo_at(time);
  92         const Meter& current_meter = session->tempo_map().meter_at(time);
  93         double frames_per_beat =
  94                 current_tempo.frames_per_beat(session->frame_rate(),
  95                                               current_meter);
  96
  97         double quarter_notes_per_beat = 4.0 / current_tempo.note_type();
  98         double frames_per_quarter_note = frames_per_beat / quarter_notes_per_beat;
  99
 100         one_ppqn_in_frames = frames_per_quarter_note / double (ppqn);
 101         // DEBUG_TRACE (DEBUG::MidiClock, string_compose ("at %1, one ppqn = %2\n", time, one_ppqn_in_frames));
 102 }
 103
 104 ARDOUR::nframes64_t
 105 MIDIClock_Slave::calculate_song_position(uint16_t song_position_in_sixteenth_notes)
 106 {
 107         nframes64_t song_position_frames = 0;
 108         for (uint16_t i = 1; i <= song_position_in_sixteenth_notes; ++i) {
 109                 // one quarter note contains ppqn pulses, so a sixteenth note is ppqn / 4 pulses
 110                 calculate_one_ppqn_in_frames_at(song_position_frames);
 111                 song_position_frames += one_ppqn_in_frames * (nframes64_t)(ppqn / 4);
 112         }
 113
 114         return song_position_frames;
 115 }
 116
 117 void
 118 MIDIClock_Slave::calculate_filter_coefficients()
 119 {
 120         // omega = 2 * PI * Bandwidth / MIDI clock frame frequency in Hz
 121         omega = 2.0 * M_PI * bandwidth * one_ppqn_in_frames / session->frame_rate();
 122         b = 1.4142135623730950488 * omega;
 123         c = omega * omega;
 124 }
 125
 126 void
 127 MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, nframes64_t timestamp)
 128 {
 129         // some pieces of hardware send MIDI Clock all the time
 130         if ( (!_starting) && (!_started) ) {
 131                 return;
 132         }
 133
 134         calculate_one_ppqn_in_frames_at(should_be_position);
 135
 136         nframes64_t elapsed_since_start = timestamp - first_timestamp;
 137         double error = 0;
 138
 139         if (_starting || last_timestamp == 0) {
 140                 midi_clock_count = 0;
 141
 142                 first_timestamp = timestamp;
 143                 elapsed_since_start = should_be_position;
 144
 145                 // calculate filter coefficients
 146                 calculate_filter_coefficients();
 147
 148                 // initialize DLL
 149                 e2 = double(one_ppqn_in_frames) / double(session->frame_rate());
 150                 t0 = double(elapsed_since_start) / double(session->frame_rate());
 151                 t1 = t0 + e2;
 152
 153                 // let ardour go after first MIDI Clock Event
 154                 _starting = false;
 155         } else {
 156                 midi_clock_count++;
 157                 should_be_position  += one_ppqn_in_frames;
 158                 calculate_filter_coefficients();
 159
 160                 // calculate loop error
 161                 // we use session->audible_frame() instead of t1 here
 162                 // because t1 is used to calculate the transport speed,
 163                 // so the loop will compensate for accumulating rounding errors
 164                 error = (double(should_be_position) - double(session->audible_frame()));
 165                 e = error / double(session->frame_rate());
 166
 167                 // update DLL
 168                 t0 = t1;
 169                 t1 += b * e + e2;
 170                 e2 += c * e;
 171         }
 172
 173         DEBUG_TRACE (DEBUG::MidiClock, string_compose ("clock #%1 @ %2 arrived %3 (theoretical) audible %4 transport %5 error %6 "
 174                                                        "read delta %7 should-be delta %8 t1-t0 %9 t0 %10 t1 %11 framerate %12 appspeed %13\n",
 175                                                        midi_clock_count,
 176                                                        elapsed_since_start,
 177                                                        should_be_position,
 178                                                        session->audible_frame(),
 179                                                        session->transport_frame(),
 180                                                        error,
 181                                                        timestamp - last_timestamp,
 182                                                        one_ppqn_in_frames,
 183                                                        (t1 -t0) * session->frame_rate(),
 184                                                        t0 * session->frame_rate(),
 185                                                        t1 * session->frame_rate(),
 186                                                        session->frame_rate(),
 187                                                        ((t1 - t0) * session->frame_rate()) / one_ppqn_in_frames));
 188
 189         last_timestamp = timestamp;
 190 }
 191
 192 void
 193 MIDIClock_Slave::start (Parser& /*parser*/, nframes64_t timestamp)
 194 {
 195         DEBUG_TRACE (DEBUG::MidiClock, string_compose ("MIDIClock_Slave got start message at time %1 engine time %2\n", timestamp, session->frame_time()));
 196
 197         if (!_started) {
 198                 reset();
 199
 200                 _started = true;
 201                 _starting = true;
 202
 203                 should_be_position = session->transport_frame();
 204         }
 205 }
 206
 207 void
 208 MIDIClock_Slave::reset ()
 209 {
 210         should_be_position = session->transport_frame();
 211         last_timestamp = 0;
 212
 213         _starting = true;
 214         _started  = true;
 215
 216         // session->request_locate(0, false);
 217 }
 218
 219 void
 220 MIDIClock_Slave::contineu (Parser& /*parser*/, nframes64_t /*timestamp*/)
 221 {
 222         DEBUG_TRACE (DEBUG::MidiClock, "MIDIClock_Slave got continue message\n");
 223
 224         if (!_started) {
 225                 _starting = true;
 226                 _started  = true;
 227         }
 228 }
 229
 230
 231 void
 232 MIDIClock_Slave::stop (Parser& /*parser*/, nframes64_t /*timestamp*/)
 233 {
 234         DEBUG_TRACE (DEBUG::MidiClock, "MIDIClock_Slave got stop message\n");
 235
 236         if (_started || _starting) {
 237                 _starting = false;
 238                 _started  = false;
 239                 // locate to last MIDI clock position
 240                 session->request_transport_speed(0.0);
 241
 242                 // we need to go back to the last MIDI beat (6 ppqn)
 243                 // and lets hope the tempo didnt change in the meantime :)
 244
 245                 // begin at the should be position, because
 246                 // that is the position of the last MIDI Clock
 247                 // message and that is probably what the master
 248                 // expects where we are right now
 249                 nframes64_t stop_position = should_be_position;
 250
 251                 // find out the last MIDI beat: go back #midi_clocks mod 6
 252                 // and lets hope the tempo didnt change in those last 6 beats :)
 253                 stop_position -= (midi_clock_count % 6) * one_ppqn_in_frames;
 254
 255                 session->request_locate(stop_position, false);
 256                 should_be_position = stop_position;
 257                 last_timestamp = 0;
 258         }
 259 }
 260
 261 void
 262 MIDIClock_Slave::position (Parser& /*parser*/, byte* message, size_t size)
 263 {
 264         // we are note supposed to get position messages while we are running
 265         // so lets be robust and ignore those
 266         if (_started || _starting) {
 267                 return;
 268         }
 269
 270         assert(size == 3);
 271         byte lsb = message[1];
 272         byte msb = message[2];
 273         assert((lsb <= 0x7f) && (msb <= 0x7f));
 274
 275         uint16_t position_in_sixteenth_notes = (uint16_t(msb) << 7) | uint16_t(lsb);
 276         nframes64_t position_in_frames = calculate_song_position(position_in_sixteenth_notes);
 277
 278         DEBUG_TRACE (DEBUG::MidiClock, string_compose ("Song Position: %1 frames: %2\n", position_in_sixteenth_notes, position_in_frames));
 279
 280         session->request_locate(position_in_frames, false);
 281         should_be_position  = position_in_frames;
 282         last_timestamp = 0;
 283
 284 }
 285
 286 bool
 287 MIDIClock_Slave::locked () const
 288 {
 289         return true;
 290 }
 291
 292 bool
 293 MIDIClock_Slave::ok() const
 294 {
 295         return true;
 296 }
 297
 298 bool
 299 MIDIClock_Slave::starting() const
 300 {
 301         return false;
 302 }
 303
 304 bool
 305 MIDIClock_Slave::stop_if_no_more_clock_events(nframes64_t& pos, nframes64_t now)
 306 {
 307         /* no timecode for 1/4 second ? conclude that its stopped */
 308         if (last_timestamp &&
 309             now > last_timestamp &&
 310             now - last_timestamp > session->frame_rate() / 4) {
 311                 DEBUG_TRACE (DEBUG::MidiClock, "No MIDI Clock frames received for some time, stopping!\n");
 312                 pos = should_be_position;
 313                 session->request_transport_speed (0);
 314                 session->request_locate (should_be_position, false);
 315                 return true;
 316         } else {
 317                 return false;
 318         }
 319 }
 320
 321 bool
 322 MIDIClock_Slave::speed_and_position (double& speed, nframes64_t& pos)
 323 {
 324         if (!_started || _starting) {
 325                 speed = 0.0;
 326                 pos   = should_be_position;
 327                 return true;
 328         }
 329
 330         nframes64_t engine_now = session->frame_time();
 331
 332         if (stop_if_no_more_clock_events(pos, engine_now)) {
 333                 return false;
 334         }
 335
 336         // calculate speed
 337         speed = ((t1 - t0) * session->frame_rate()) / one_ppqn_in_frames;
 338
 339         // provide a 3% deadzone to lock the speed
 340         if (fabs(speed - 1.0) <= 0.03)
 341                 speed = 1.0;
 342
 343         // calculate position
 344         if (engine_now > last_timestamp) {
 345                 // we are in between MIDI clock messages
 346                 // so we interpolate position according to speed
 347                 nframes64_t elapsed = engine_now - last_timestamp;
 348                 pos = (nframes64_t) (should_be_position + double(elapsed) * speed);
 349         } else {
 350                 // A new MIDI clock message has arrived this cycle
 351                 pos = should_be_position;
 352         }
 353
 354         DEBUG_TRACE (DEBUG::MidiClock, string_compose ("speed_and_position: %1 & %2 <-> %3 (transport)\n", speed, pos, session->transport_frame()));
 355
 356         return true;
 357 }
 358
 359 ARDOUR::nframes_t
 360 MIDIClock_Slave::resolution() const
 361 {
 362         // one beat
 363         return (nframes_t) one_ppqn_in_frames * ppqn;
 364 }
 365