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