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