libs/ardour/session_ltc.cc

   1 /*
   2   Copyright (C) 2012 Paul Davis
   3   Written by Robin Gareus <robin@gareus.org>
   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 #include "ardour/debug.h"
  21 #include "timecode/time.h"
  22 #include "ardour/session.h"
  23 #include "ardour/audioengine.h"
  24 #include "ardour/audio_port.h"
  25
  26 #include "i18n.h"
  27
  28 using namespace std;
  29 using namespace ARDOUR;
  30 using namespace MIDI;
  31 using namespace PBD;
  32 using namespace Timecode;
  33
  34 //#define LTC_GEN_FRAMEDBUG
  35
  36 void
  37 Session::ltc_tx_initialize()
  38 {
  39         ltc_enc_tcformat = config.get_timecode_format();
  40
  41         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX init sr: %1 fps: %2\n", nominal_frame_rate(), timecode_to_frames_per_second(ltc_enc_tcformat)));
  42         ltc_encoder = ltc_encoder_create(nominal_frame_rate(),
  43                         timecode_to_frames_per_second(ltc_enc_tcformat),
  44                         0);
  45
  46         ltc_encoder_set_bufsize(ltc_encoder, nominal_frame_rate(), 23.0);
  47
  48         /* buffersize for 1 LTC frame: (1 + sample-rate / fps) bytes
  49          * usually returned by ltc_encoder_get_buffersize(encoder)
  50          *
  51          * since the fps can change and A3's  min fps: 24000/1001 */
  52         ltc_enc_buf = (ltcsnd_sample_t*) calloc((nominal_frame_rate() / 23), sizeof(ltcsnd_sample_t));
  53         ltc_speed = 0;
  54         ltc_tx_reset();
  55 }
  56
  57 void
  58 Session::ltc_tx_cleanup()
  59 {
  60         DEBUG_TRACE (DEBUG::LTC, "LTC TX cleanup\n");
  61         if (ltc_enc_buf) free(ltc_enc_buf);
  62         ltc_encoder_free(ltc_encoder);
  63         ltc_encoder = NULL;
  64 }
  65
  66 void
  67 Session::ltc_tx_reset()
  68 {
  69         DEBUG_TRACE (DEBUG::LTC, "LTC TX reset\n");
  70         ltc_enc_pos = -1; // force re-start
  71         ltc_buf_len = 0;
  72         ltc_buf_off = 0;
  73         ltc_enc_byte = 0;
  74 }
  75
  76 int
  77 Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end_frame,
  78                 double target_speed, double current_speed,
  79                 pframes_t nframes)
  80 {
  81         assert(nframes > 0);
  82
  83         const float smult = 2.0/(3.0*255.0);
  84         SMPTETimecode tc;
  85         jack_default_audio_sample_t *out;
  86         pframes_t txf = 0;
  87         boost::shared_ptr<Port> ltcport = engine().ltc_output_port();
  88
  89         if (!ltc_encoder || !ltc_enc_buf || !ltcport || ! ltcport->jack_port()) return 0;
  90
  91         out = (jack_default_audio_sample_t*) jack_port_get_buffer (ltcport->jack_port(), nframes);
  92         if (!out) return 0;
  93
  94         if (engine().freewheeling() || !Config->get_send_ltc()) {
  95                 memset(out, 0, nframes * sizeof(jack_default_audio_sample_t));
  96                 return nframes;
  97         }
  98
  99         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX %1 to %2 / %3\n", start_frame, end_frame, nframes));
 100
 101         /* all systems go. Now here's the plan:
 102          *
 103          *  1) check if fps has changed
 104          *  2) check direction of encoding, calc speed
 105          *  3) calculate frame and byte to send aligned to jack-period size
 106          *  4) check if it's the frame/byte that is already in the queue
 107          *  5) if (4) mismatch, re-calculate offset of LTC frame relative to period size
 108          *  6) actual LTC audio output
 109          *  6a) send remaining part of already queued frame; break on nframes
 110          *  6b) encode new LTC-frame byte
 111          *  6c) goto 6a
 112          *  7) done
 113          */
 114
 115         // (1)
 116         TimecodeFormat cur_timecode = config.get_timecode_format();
 117         if (cur_timecode != ltc_enc_tcformat) {
 118                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX1: TC format mismatch - reinit sr: %1 fps: %2\n", nominal_frame_rate(), timecode_to_frames_per_second(cur_timecode)));
 119                 if (ltc_encoder_reinit(ltc_encoder, nominal_frame_rate(), timecode_to_frames_per_second(cur_timecode), 0)) {
 120                         PBD::error << _("LTC encoder: invalid framerate - LTC encoding is disabled for the remainder of this session.") << endmsg;
 121                         ltc_tx_cleanup();
 122                         return 0;
 123                 }
 124                 ltc_enc_tcformat = cur_timecode;
 125                 ltc_tx_reset();
 126         }
 127
 128         /* LTC is max. 30 fps */
 129         if (timecode_to_frames_per_second(cur_timecode) > 30) {
 130                 memset(out, 0, nframes * sizeof(jack_default_audio_sample_t));
 131                 return nframes;
 132         }
 133
 134         // (2)
 135 #define SIGNUM(a) ( (a) < 0 ? -1 : 1)
 136
 137         framepos_t cycle_start_frame = (current_speed < 0) ? end_frame :start_frame;
 138         double new_ltc_speed = double(labs(end_frame - start_frame) * SIGNUM(current_speed)) / double(nframes);
 139
 140         if (SIGNUM(new_ltc_speed) != SIGNUM (ltc_speed)) {
 141                 // transport changed direction
 142                 DEBUG_TRACE (DEBUG::LTC, "LTC TX2: transport direction changed\n");
 143                 ltc_tx_reset();
 144         }
 145
 146         if (ltc_speed != current_speed || target_speed != fabs(current_speed)) {
 147                 /* TODO check ./libs/ardour/interpolation.cc  CubicInterpolation::interpolate
 148                  * if target_speed != current_speed we should interpolate, too.
 149                  *
 150                  * However, currenly in A3 target_speed == current_speed for each process cycle
 151                  * (except for the sign). Besides, above speed calulation uses the
 152                  * difference (end_frame - start_frame).
 153                  * end_frame is calculated from 'frames_moved' which includes the interpolation.
 154                  * so we're good, except for the fact that each LTC byte is sent at fixed speed.
 155                  */
 156                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: speed change old: %1 cur: %2 tgt: %3 ctd: %4\n", ltc_speed, current_speed, target_speed, fabs(current_speed) - target_speed));
 157         }
 158
 159         if (end_frame == start_frame || fabs(current_speed) < 0.1 ) {
 160                 DEBUG_TRACE (DEBUG::LTC, "LTC TX2: transport is not rolling or absolute-speed < 0.1\n");
 161                 /* keep repeating current frame
 162                  *
 163                  * an LTC generator must be able to continue generating LTC when Ardours transport is in stop
 164                  * some machines do odd things if LTC goes away:
 165                  * e.g. a tape based machine (video or audio), some think they have gone into park if LTC goes away,
 166                  * so unspool the tape from the playhead. That might be inconvenient.
 167                  * If LTC keeps arriving they remain in a stop position with the tape on the playhead.
 168                  */
 169                 new_ltc_speed = 0;
 170         }
 171
 172         ltc_speed = new_ltc_speed;
 173         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: transport speed %1.\n", ltc_speed));
 174
 175         if (fabs(ltc_speed) > 10.0) {
 176                 DEBUG_TRACE (DEBUG::LTC, "LTC TX2: speed is out of bounds.\n");
 177                 ltc_tx_reset();
 178                 memset(out, 0, nframes * sizeof(jack_default_audio_sample_t));
 179                 return nframes;
 180         }
 181
 182         // (3)
 183         Timecode::Time tc_start;
 184         framepos_t tc_sample_start;
 185
 186         /* calc timecode frame from current position - round down to nearest timecode */
 187         int boff;
 188         if (ltc_speed == 0) {
 189                 boff = 0;
 190         }       else if (ltc_speed < 0) {
 191                 boff = (ltc_enc_byte - 9) * frames_per_timecode_frame() / 10;
 192         } else {
 193                 boff = ltc_enc_byte * frames_per_timecode_frame() / 10;
 194         }
 195
 196         sample_to_timecode(cycle_start_frame
 197                         - boff
 198                         - ltc_speed * (ltc_buf_len - ltc_buf_off),
 199                         tc_start, true, false);
 200
 201         /* convert timecode back to sample-position */
 202         Timecode::timecode_to_sample (tc_start, tc_sample_start, true, false,
 203                 double(frame_rate()),
 204                 config.get_subframes_per_frame(),
 205                 config.get_timecode_offset_negative(), config.get_timecode_offset()
 206                 );
 207
 208         /* difference between current frame and TC frame in samples */
 209         frameoffset_t soff = cycle_start_frame - tc_sample_start;
 210         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX3: now: %1 tra: %2 eoff %3\n", cycle_start_frame, tc_sample_start, soff));
 211
 212         // (4)
 213         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX4: enc: %1 boff: %2 || enc-byte:%3\n", ltc_enc_pos, boff, ltc_enc_byte));
 214         if (ltc_enc_pos != tc_sample_start) {
 215
 216                 /* re-calc timecode w/o buffer offset */
 217                 sample_to_timecode(cycle_start_frame, tc_start, true, false);
 218                 Timecode::timecode_to_sample (tc_start, tc_sample_start, true, false,
 219                         double(frame_rate()),
 220                         config.get_subframes_per_frame(),
 221                         config.get_timecode_offset_negative(), config.get_timecode_offset()
 222                         );
 223                 soff = cycle_start_frame - tc_sample_start;
 224                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX4: now: %1 trs: %2 toff %3\n", cycle_start_frame, tc_sample_start, soff));
 225
 226                 tc.hours = tc_start.hours;
 227                 tc.mins = tc_start.minutes;
 228                 tc.secs = tc_start.seconds;
 229                 tc.frame = tc_start.frames;
 230                 ltc_encoder_set_timecode(ltc_encoder, &tc);
 231
 232 #if 1
 233                 /* workaround for libltc recognizing 29.97 and 30000/1001 as drop-frame TC.
 234                  * in A3 only 30000/1001 is drop-frame and there are also other questionable
 235                  * DF timecodes  such as 24k/1001 and 25k/1001.
 236                  */
 237                 LTCFrame ltcframe;
 238                 ltc_encoder_get_frame(ltc_encoder, &ltcframe);
 239                 ltcframe.dfbit = timecode_has_drop_frames(cur_timecode)?1:0;
 240                 ltc_encoder_set_frame(ltc_encoder, &ltcframe);
 241 #endif
 242
 243                 // (5)
 244                 int fdiff = 0;
 245                 if (soff < 0) {
 246                         fdiff = ceil(-soff / frames_per_timecode_frame());
 247                         soff += fdiff * frames_per_timecode_frame();
 248                         for (int i=0; i < fdiff; ++i) {
 249                                 ltc_encoder_inc_timecode(ltc_encoder);
 250                         }
 251                 }
 252                 else if (soff >= frames_per_timecode_frame()) {
 253                         fdiff = floor(soff / frames_per_timecode_frame());
 254                         soff -= fdiff * frames_per_timecode_frame();
 255                         for (int i=0; i < fdiff; ++i) {
 256                                 ltc_encoder_dec_timecode(ltc_encoder);
 257                         }
 258                 }
 259
 260                 assert(soff >= 0 && soff < frames_per_timecode_frame());
 261
 262                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX5 restart encoder fdiff %1 sdiff %2\n", fdiff, soff));
 263                 ltc_tx_reset();
 264
 265                 if (ltc_speed == 0) {
 266                         // offset is irrelevant when not rolling
 267                         soff = 0;
 268                 }
 269                 if (soff > 0 && soff <= nframes) {
 270                         txf=soff;
 271                         memset(out, 0, soff * sizeof(jack_default_audio_sample_t));
 272                 } else if (soff > 0) {
 273                         /* resync next cycle */
 274                         memset(out, 0, soff * sizeof(jack_default_audio_sample_t));
 275                         return nframes;
 276                 }
 277
 278                 ltc_enc_byte = soff * 10 / frames_per_timecode_frame();
 279
 280                 if (ltc_speed < 0 ) {
 281                         ltc_enc_byte = 9 - ltc_enc_byte;
 282                 }
 283
 284                 ltc_enc_pos = tc_sample_start;
 285                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX5 restart @ %1 byte %2\n", ltc_enc_pos, ltc_enc_byte));
 286         }
 287
 288         // (6)
 289         while (1) {
 290 #ifdef LTC_GEN_FRAMEDBUG
 291                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.1 @%1  [ %2 / %3 ]\n", txf, ltc_buf_off, ltc_buf_len));
 292 #endif
 293                 // (6a)
 294                 while ((ltc_buf_off < ltc_buf_len) && (txf < nframes)) {
 295                         const float v1 = ltc_enc_buf[ltc_buf_off++] - 128.0;
 296                         const jack_default_audio_sample_t val = (jack_default_audio_sample_t) (v1*smult);
 297                         out[txf++] = val;
 298                 }
 299 #ifdef LTC_GEN_FRAMEDBUG
 300                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.2 @%1  [ %2 / %3 ]\n", txf, ltc_buf_off, ltc_buf_len));
 301 #endif
 302
 303                 if (txf >= nframes) {
 304                         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX7 txf = %1 nframes = %2\n", txf, nframes));
 305                         return nframes;
 306                 }
 307
 308                 ltc_buf_len = 0;
 309                 ltc_buf_off = 0;
 310
 311                 // (6b)
 312
 313                 if (SIGNUM(ltc_speed) == -1) {
 314                         ltc_enc_byte = (ltc_enc_byte + 9)%10;
 315                         if (ltc_enc_byte == 9) {
 316                                 ltc_encoder_dec_timecode(ltc_encoder);
 317 #if 0 // this does not work for fractional or drop-frame TC
 318                                 ltc_enc_pos -= frames_per_timecode_frame();
 319 #else // TODO make this a function
 320                                 SMPTETimecode enctc;
 321                                 Timecode::Time a3tc;
 322                                 ltc_encoder_get_timecode(ltc_encoder, &enctc);
 323
 324                                 a3tc.hours   = enctc.hours ;
 325                                 a3tc.minutes = enctc.mins  ;
 326                                 a3tc.seconds = enctc.secs  ;
 327                                 a3tc.frames  = enctc.frame ;
 328                                 a3tc.rate = timecode_to_frames_per_second(cur_timecode);
 329                                 a3tc.drop = timecode_has_drop_frames(cur_timecode);
 330
 331                                 Timecode::timecode_to_sample (a3tc, ltc_enc_pos, true, false,
 332                                         double(frame_rate()),
 333                                         config.get_subframes_per_frame(),
 334                                         config.get_timecode_offset_negative(), config.get_timecode_offset()
 335                                         );
 336 #endif
 337                         }
 338                 }
 339
 340                 if (ltc_encoder_encode_byte(ltc_encoder, ltc_enc_byte, (ltc_speed==0)?1.0:(1.0/ltc_speed))) {
 341                         DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.3 encoder error byte %1\n", ltc_enc_byte));
 342                         ltc_encoder_buffer_flush(ltc_encoder);
 343                         ltc_tx_reset();
 344                         memset(out, 0, nframes * sizeof(jack_default_audio_sample_t));
 345                         return -1;
 346                 }
 347                 int enc_frames = ltc_encoder_get_buffer(ltc_encoder, &(ltc_enc_buf[ltc_buf_len]));
 348 #ifdef LTC_GEN_FRAMEDBUG
 349                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.3 encoded %1 bytes LTC-byte %2 at spd %3\n", enc_frames, ltc_enc_byte, ltc_speed));
 350 #endif
 351                 if (enc_frames <=0) {
 352                         DEBUG_TRACE (DEBUG::LTC, "LTC TX6.3 encoder empty buffer.\n");
 353                         ltc_encoder_buffer_flush(ltc_encoder);
 354                         ltc_tx_reset();
 355                         memset(out, 0, nframes * sizeof(jack_default_audio_sample_t));
 356                         return -1;
 357                 }
 358
 359                 ltc_buf_len += enc_frames;
 360
 361                 if (SIGNUM(ltc_speed) == 1) {
 362                         ltc_enc_byte = (ltc_enc_byte + 1)%10;
 363                         if (ltc_enc_byte == 0 && ltc_speed != 0) {
 364                                 ltc_encoder_inc_timecode(ltc_encoder);
 365 #if 0 // this does not work for fractional or drop-frame TC
 366                                 ltc_enc_pos += frames_per_timecode_frame();
 367 #else // TODO make this a function
 368                                 SMPTETimecode enctc;
 369                                 Timecode::Time a3tc;
 370                                 ltc_encoder_get_timecode(ltc_encoder, &enctc);
 371
 372                                 a3tc.hours   = enctc.hours ;
 373                                 a3tc.minutes = enctc.mins  ;
 374                                 a3tc.seconds = enctc.secs  ;
 375                                 a3tc.frames  = enctc.frame ;
 376                                 a3tc.rate = timecode_to_frames_per_second(cur_timecode);
 377                                 a3tc.drop = timecode_has_drop_frames(cur_timecode);
 378
 379                                 Timecode::timecode_to_sample (a3tc, ltc_enc_pos, true, false,
 380                                         double(frame_rate()),
 381                                         config.get_subframes_per_frame(),
 382                                         config.get_timecode_offset_negative(), config.get_timecode_offset()
 383                                         );
 384 #endif
 385                         }
 386                 }
 387 #ifdef LTC_GEN_FRAMEDBUG
 388                 DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.4 fno: %1  [ %2 / %3 ] spd %4\n", ltc_enc_pos, ltc_buf_off, ltc_buf_len, ltc_speed));
 389 #endif
 390         }
 391
 392         return nframes;
 393 }