libs/ardour/ltc_slave.cc

   1 /*
   2     Copyright (C) 2012 Paul Davis
   3     Witten by 2012 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 <iostream>
  21 #include <errno.h>
  22 #include <poll.h>
  23 #include <sys/types.h>
  24 #include <unistd.h>
  25
  26 #include "pbd/error.h"
  27
  28 #include "ardour/debug.h"
  29 #include "ardour/slave.h"
  30 #include "ardour/session.h"
  31 #include "ardour/audioengine.h"
  32 #include "ardour/audio_port.h"
  33
  34 #include "i18n.h"
  35
  36 using namespace std;
  37 using namespace ARDOUR;
  38 using namespace MIDI;
  39 using namespace PBD;
  40 using namespace Timecode;
  41
  42 #define FLYWHEEL_TIMEOUT ( 1 * session.frame_rate() )
  43
  44 LTC_Slave::LTC_Slave (Session& s)
  45         : session (s)
  46 {
  47         frames_per_ltc_frame = session.frames_per_timecode_frame();
  48         timecode.rate = session.timecode_frames_per_second();
  49         timecode.drop  = session.timecode_drop_frames();
  50
  51         did_reset_tc_format = false;
  52         delayedlocked = 10;
  53         monotonic_cnt = 0;
  54         fps_detected=false;
  55
  56         ltc_timecode = session.config.get_timecode_format();
  57         a3e_timecode = session.config.get_timecode_format();
  58         printed_timecode_warning = false;
  59         ltc_detect_fps_cnt = ltc_detect_fps_max = 0;
  60         memset(&prev_frame, 0, sizeof(LTCFrameExt));
  61
  62         decoder = ltc_decoder_create((int) frames_per_ltc_frame, 128 /*queue size*/);
  63
  64         session.config.ParameterChanged.connect_same_thread (config_connection, boost::bind (&LTC_Slave::parameter_changed, this, _1));
  65         parse_timecode_offset();
  66         reset();
  67         resync_latency();
  68         session.Xrun.connect_same_thread (port_connections, boost::bind (&LTC_Slave::resync_xrun, this));
  69         session.engine().GraphReordered.connect_same_thread (port_connections, boost::bind (&LTC_Slave::resync_latency, this));
  70 }
  71
  72 LTC_Slave::~LTC_Slave()
  73 {
  74         port_connections.drop_connections();
  75         config_connection.disconnect();
  76
  77         if (did_reset_tc_format) {
  78                 session.config.set_timecode_format (saved_tc_format);
  79         }
  80
  81         ltc_decoder_free(decoder);
  82 }
  83
  84 void
  85 LTC_Slave::parse_timecode_offset() {
  86         Timecode::Time offset_tc;
  87         Timecode::parse_timecode_format(session.config.get_slave_timecode_offset(), offset_tc);
  88         offset_tc.rate = session.timecode_frames_per_second();
  89         offset_tc.drop = session.timecode_drop_frames();
  90         session.timecode_to_sample(offset_tc, timecode_offset, false, false);
  91         timecode_negative_offset = offset_tc.negative;
  92 }
  93
  94 void
  95 LTC_Slave::parameter_changed (std::string const & p)
  96 {
  97         if (p == "slave-timecode-offset"
  98                         || p == "subframes-per-frame"
  99                         || p == "timecode-format"
 100                         ) {
 101                 parse_timecode_offset();
 102         }
 103 }
 104
 105 ARDOUR::framecnt_t
 106 LTC_Slave::resolution () const
 107 {
 108         return (framecnt_t) (session.frame_rate() / 1000);
 109 }
 110
 111 bool
 112 LTC_Slave::locked () const
 113 {
 114         return (delayedlocked < 5);
 115 }
 116
 117 bool
 118 LTC_Slave::ok() const
 119 {
 120         return true;
 121 }
 122
 123 void
 124 LTC_Slave::resync_xrun()
 125 {
 126         DEBUG_TRACE (DEBUG::LTC, "LTC resync_xrun()\n");
 127         engine_dll_initstate = 0;
 128 }
 129
 130 void
 131 LTC_Slave::resync_latency()
 132 {
 133         DEBUG_TRACE (DEBUG::LTC, "LTC resync_latency()\n");
 134         engine_dll_initstate = 0;
 135
 136         if (!session.deletion_in_progress() && session.ltc_output_io()) { /* check if Port exits */
 137                 boost::shared_ptr<Port> ltcport = session.ltc_input_port();
 138                 ltcport->get_connected_latency_range(ltc_slave_latency, false);
 139         }
 140 }
 141
 142 void
 143 LTC_Slave::reset()
 144 {
 145         DEBUG_TRACE (DEBUG::LTC, "LTC reset()\n");
 146         last_timestamp = 0;
 147         current_delta = 0;
 148         transport_direction = 0;
 149         ltc_speed = 0;
 150         engine_dll_initstate = 0;
 151 }
 152
 153 void
 154 LTC_Slave::parse_ltc(const jack_nframes_t nframes, const jack_default_audio_sample_t * const in, const framecnt_t posinfo)
 155 {
 156         jack_nframes_t i;
 157         unsigned char sound[8192];
 158         if (nframes > 8192) {
 159                 /* TODO warn once or wrap, loop conversion below
 160                  * does jack/A3 support > 8192 spp anyway?
 161                  */
 162                 return;
 163         }
 164
 165         for (i = 0; i < nframes; i++) {
 166                 const int snd=(int)rint((127.0*in[i])+128.0);
 167                 sound[i] = (unsigned char) (snd&0xff);
 168         }
 169         ltc_decoder_write(decoder, sound, nframes, posinfo);
 170         return;
 171 }
 172
 173 bool
 174 LTC_Slave::equal_ltc_frame_time(LTCFrame *a, LTCFrame *b) {
 175         if (       a->frame_units != b->frame_units
 176                 || a->frame_tens  != b->frame_tens
 177                 || a->dfbit       != b->dfbit
 178                 || a->secs_units  != b->secs_units
 179                 || a->secs_tens   != b->secs_tens
 180                 || a->mins_units  != b->mins_units
 181                 || a->mins_tens   != b->mins_tens
 182                 || a->hours_units != b->hours_units
 183                 || a->hours_tens  != b->hours_tens
 184              ) {
 185                 return false;
 186         }
 187         return true;
 188 }
 189
 190 bool
 191 LTC_Slave::detect_discontinuity(LTCFrameExt *frame, int fps, bool fuzzy) {
 192         bool discontinuity_detected = false;
 193
 194         if (fuzzy && (
 195                   ( frame->reverse && prev_frame.ltc.frame_units == 0)
 196                 ||(!frame->reverse && frame->ltc.frame_units == 0)
 197                 )) {
 198                 memcpy(&prev_frame, frame, sizeof(LTCFrameExt));
 199                 return false;
 200         }
 201
 202         if (frame->reverse) {
 203                 ltc_frame_decrement(&prev_frame.ltc, fps , 0);
 204         } else {
 205                 ltc_frame_increment(&prev_frame.ltc, fps , 0);
 206         }
 207         if (!equal_ltc_frame_time(&prev_frame.ltc, &frame->ltc)) {
 208                 discontinuity_detected = true;
 209         }
 210
 211     memcpy(&prev_frame, frame, sizeof(LTCFrameExt));
 212     return discontinuity_detected;
 213 }
 214
 215 bool
 216 LTC_Slave::detect_ltc_fps(int frameno, bool df)
 217 {
 218         bool fps_changed = false;
 219         double detected_fps = 0;
 220         if (frameno > ltc_detect_fps_max)
 221         {
 222                 ltc_detect_fps_max = frameno;
 223         }
 224         ltc_detect_fps_cnt++;
 225
 226         if (ltc_detect_fps_cnt > 40) {
 227                 if (ltc_detect_fps_cnt > ltc_detect_fps_max) {
 228                         detected_fps = ltc_detect_fps_max + 1;
 229                         if (df) {
 230                                 /* LTC df -> indicates fractional framerate */
 231                                 if (Config->get_timecode_source_2997()) {
 232                                         detected_fps = detected_fps * 999.0 / 1000.0;
 233                                 } else {
 234                                         detected_fps = detected_fps * 1000.0 / 1001.0;
 235                                 }
 236                         }
 237
 238                         if (timecode.rate != detected_fps || timecode.drop != df) {
 239                                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC detected FPS: %1%2\n", detected_fps, df?"df":"ndf"));
 240                         } else {
 241                                 detected_fps = 0; /* no cange */
 242                         }
 243                 }
 244                 ltc_detect_fps_cnt = ltc_detect_fps_max = 0;
 245         }
 246
 247         /* when changed */
 248         if (detected_fps != 0 && (detected_fps != timecode.rate || df != timecode.drop)) {
 249                 timecode.rate = detected_fps;
 250                 timecode.drop = df;
 251                 frames_per_ltc_frame = double(session.frame_rate()) / timecode.rate;
 252                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC reset to FPS: %1%2 ; audio-frames per LTC: %3\n",
 253                                 detected_fps, df?"df":"ndf", frames_per_ltc_frame));
 254                 fps_changed=true;
 255         }
 256
 257         /* poll and check session TC */
 258         TimecodeFormat tc_format = apparent_timecode_format();
 259         TimecodeFormat cur_timecode = session.config.get_timecode_format();
 260
 261         if (Config->get_timecode_sync_frame_rate()) {
 262                 /* enforce time-code */
 263                 if (!did_reset_tc_format) {
 264                         saved_tc_format = cur_timecode;
 265                         did_reset_tc_format = true;
 266                 }
 267                 if (cur_timecode != tc_format) {
 268                         if (ceil(Timecode::timecode_to_frames_per_second(cur_timecode)) != ceil(Timecode::timecode_to_frames_per_second(tc_format))) {
 269                                 warning << string_compose(_("Session framerate adjusted from %1 to LTC's %2."),
 270                                                 Timecode::timecode_format_name(cur_timecode),
 271                                                 Timecode::timecode_format_name(tc_format))
 272                                         << endmsg;
 273                         }
 274                         session.config.set_timecode_format (tc_format);
 275                 }
 276         } else {
 277                 /* only warn about TC mismatch */
 278                 if (ltc_timecode != tc_format) printed_timecode_warning = false;
 279                 if (a3e_timecode != cur_timecode) printed_timecode_warning = false;
 280
 281                 if (cur_timecode != tc_format && ! printed_timecode_warning) {
 282                         if (ceil(Timecode::timecode_to_frames_per_second(cur_timecode)) != ceil(Timecode::timecode_to_frames_per_second(tc_format))) {
 283                                 warning << string_compose(_("Session and LTC framerate mismatch: LTC:%1 Session:%2."),
 284                                                 Timecode::timecode_format_name(tc_format),
 285                                                 Timecode::timecode_format_name(cur_timecode))
 286                                         << endmsg;
 287                         }
 288                         printed_timecode_warning = true;
 289                 }
 290         }
 291         ltc_timecode = tc_format;
 292         a3e_timecode = cur_timecode;
 293
 294         return fps_changed;
 295 }
 296
 297 void
 298 LTC_Slave::process_ltc(framepos_t const now)
 299 {
 300         LTCFrameExt frame;
 301         while (ltc_decoder_read(decoder, &frame)) {
 302                 SMPTETimecode stime;
 303
 304                 ltc_frame_to_time(&stime, &frame.ltc, 0);
 305                 timecode.negative  = false;
 306                 timecode.subframes  = 0;
 307
 308                 /* set timecode.rate and timecode.drop: */
 309                 bool ltc_is_static = equal_ltc_frame_time(&prev_frame.ltc, &frame.ltc);
 310
 311                 if (detect_discontinuity(&frame, ceil(timecode.rate), !fps_detected)) {
 312                         if (fps_detected) { ltc_detect_fps_cnt = ltc_detect_fps_max = 0; }
 313                         fps_detected=false;
 314                 }
 315
 316                 if (!ltc_is_static && detect_ltc_fps(stime.frame, (frame.ltc.dfbit)? true : false)) {
 317                         reset();
 318                         fps_detected=true;
 319                 }
 320
 321 #if 0 // Devel/Debug
 322                 fprintf(stdout, "LTC %02d:%02d:%02d%c%02d | %8lld %8lld%s\n",
 323                         stime.hours,
 324                         stime.mins,
 325                         stime.secs,
 326                         (frame.ltc.dfbit) ? '.' : ':',
 327                         stime.frame,
 328                         frame.off_start,
 329                         frame.off_end,
 330                         frame.reverse ? " R" : "  "
 331                         );
 332 #endif
 333
 334                 /* when a full LTC frame is decoded, the timecode the LTC frame
 335                  * is referring has just passed.
 336                  * So we send the _next_ timecode which
 337                  * is expected to start at the end of the current frame
 338                  */
 339                 int fps_i = ceil(timecode.rate);
 340                 if (!frame.reverse) {
 341                         ltc_frame_increment(&frame.ltc, fps_i , 0);
 342                         ltc_frame_to_time(&stime, &frame.ltc, 0);
 343                         transport_direction = 1;
 344                 } else {
 345                         ltc_frame_decrement(&frame.ltc, fps_i , 0);
 346                         int off = frame.off_end - frame.off_start;
 347                         frame.off_start += off;
 348                         frame.off_end += off;
 349                         transport_direction = -1;
 350                 }
 351
 352                 timecode.hours   = stime.hours;
 353                 timecode.minutes = stime.mins;
 354                 timecode.seconds = stime.secs;
 355                 timecode.frames  = stime.frame;
 356
 357                 /* map LTC timecode to session TC setting */
 358                 framepos_t ltc_frame; ///< audio-frame corresponding to LTC frame
 359                 Timecode::timecode_to_sample (timecode, ltc_frame, true, false,
 360                         double(session.frame_rate()),
 361                         session.config.get_subframes_per_frame(),
 362                         timecode_negative_offset, timecode_offset
 363                         );
 364
 365                 framepos_t cur_timestamp = frame.off_end + 1;
 366                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC F: %1 LF: %2  N: %3 L: %4\n", ltc_frame, last_ltc_frame, cur_timestamp, last_timestamp));
 367                 if (frame.off_end + 1 <= last_timestamp || last_timestamp == 0) {
 368                         DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC speed: UNCHANGED: %1\n", ltc_speed));
 369                 } else {
 370                         ltc_speed = double(ltc_frame - last_ltc_frame) / double(cur_timestamp - last_timestamp);
 371                         DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC speed: %1\n", ltc_speed));
 372                 }
 373
 374                 if (fabs(ltc_speed) > 10.0) {
 375                         ltc_speed = 0;
 376                 }
 377
 378                 last_timestamp = frame.off_end + 1;
 379                 last_ltc_frame = ltc_frame;
 380         } /* end foreach decoded LTC frame */
 381 }
 382
 383 void
 384 LTC_Slave::init_engine_dll (framepos_t pos, int32_t inc)
 385 {
 386         double omega = 2.0 * M_PI * double(inc) / double(session.frame_rate());
 387         b = 1.4142135623730950488 * omega;
 388         c = omega * omega;
 389
 390         e2 = double(ltc_speed * inc);
 391         t0 = double(pos);
 392         t1 = t0 + e2;
 393         DEBUG_TRACE (DEBUG::LTC, string_compose ("[re-]init Engine DLL %1 %2 %3\n", t0, t1, e2));
 394 }
 395
 396 /* main entry point from session_process.cc
 397  * called from jack_process callback context
 398  * so it is OK to use jack_port_get_buffer()
 399  */
 400 bool
 401 LTC_Slave::speed_and_position (double& speed, framepos_t& pos)
 402 {
 403         bool engine_init_called = false;
 404         framepos_t now = session.engine().frame_time_at_cycle_start();
 405         framepos_t sess_pos = session.transport_frame(); // corresponds to now
 406         framecnt_t nframes = session.engine().frames_per_cycle();
 407
 408         jack_default_audio_sample_t *in;
 409
 410         boost::shared_ptr<Port> ltcport = session.ltc_input_port();
 411
 412         in = (jack_default_audio_sample_t*) jack_port_get_buffer (ltcport->jack_port(), nframes);
 413
 414         frameoffset_t skip = now - (monotonic_cnt + nframes);
 415         monotonic_cnt = now;
 416         DEBUG_TRACE (DEBUG::LTC, string_compose ("speed_and_position - TID:%1 | latency: %2 | skip %3\n", ::pthread_self(), ltc_slave_latency.max, skip));
 417
 418         if (last_timestamp == 0) {
 419                 engine_dll_initstate = 0;
 420                 delayedlocked++;
 421         }
 422         else if (engine_dll_initstate != transport_direction && ltc_speed != 0) {
 423                 engine_dll_initstate = transport_direction;
 424                 init_engine_dll(last_ltc_frame + rint(ltc_speed * double(2 * nframes + now - last_timestamp)),
 425                                 session.engine().frames_per_cycle());
 426                 engine_init_called = true;
 427         }
 428
 429         if (in) {
 430                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC Process eng-tme: %1 eng-pos: %2\n", now, sess_pos));
 431                 /* when the jack-graph changes and if ardour performs
 432                  * locates, the audioengine is stopped (skipping frames) while
 433                  * jack [time] moves along.
 434                  */
 435                 if (skip > 0) {
 436                         DEBUG_TRACE (DEBUG::LTC, string_compose("engine skipped %1 frames. Feeding silence to LTC parser.\n", skip));
 437                         if (skip >= 8192) skip = 8192;
 438                         unsigned char sound[8192];
 439                         memset(sound, 0, sizeof(char) * skip);
 440                         ltc_decoder_write(decoder, sound, nframes, now);
 441                 } else if (skip != 0) {
 442                         /* this should never happen. it may if monotonic_cnt, now overflow on 64bit */
 443                         DEBUG_TRACE (DEBUG::LTC, string_compose("engine skipped %1 frames\n", skip));
 444                         reset();
 445                 }
 446
 447                 parse_ltc(nframes, in, now - ltc_slave_latency.max );
 448                 process_ltc(now);
 449         }
 450
 451         if (last_timestamp == 0) {
 452                 DEBUG_TRACE (DEBUG::LTC, "last timestamp == 0\n");
 453                 speed = 0;
 454                 pos = session.transport_frame();
 455                 return true;
 456         } else if (ltc_speed != 0) {
 457                 delayedlocked = 0;
 458         }
 459
 460         if (abs(now - last_timestamp) > FLYWHEEL_TIMEOUT) {
 461                 DEBUG_TRACE (DEBUG::LTC, "flywheel timeout\n");
 462                 reset();
 463                 speed = 0;
 464                 pos = session.transport_frame();
 465                 return true;
 466         }
 467
 468         /* it take 2 cycles from naught to rolling.
 469          * during these to initial cycles the speed == 0
 470          *
 471          * the first cycle:
 472          * DEBUG::Slave: slave stopped, move to NNN
 473          * DEBUG::Transport: Request forced locate to NNN
 474          * DEBUG::Slave: slave state 0 @ NNN speed 0 cur delta VERY-LARGE-DELTA avg delta 1800
 475          * DEBUG::Slave: silent motion
 476          * DEBUG::Transport: realtime stop @ NNN
 477          * DEBUG::Transport: Butler transport work, todo = PostTransportStop,PostTransportLocate,PostTransportClearSubstate
 478          *
 479          * [engine skips frames to locate, jack time keeps rolling on]
 480          *
 481          * the second cycle:
 482          *
 483          * DEBUG::LTC: [re-]init Engine DLL
 484          * DEBUG::Slave: slave stopped, move to NNN+
 485          * ...
 486          *
 487          * we need to seek two cycles ahead: 2 * nframes
 488          */
 489         if (engine_dll_initstate == 0) {
 490                 DEBUG_TRACE (DEBUG::LTC, "engine DLL not initialized. ltc_speed\n");
 491                 speed = 0;
 492                 pos = last_ltc_frame + rint(ltc_speed * double(2 * nframes + now - last_timestamp));
 493                 return true;
 494         }
 495
 496         /* interpolate position according to speed and time since last LTC-frame*/
 497         double speed_flt = ltc_speed;
 498         double elapsed = (now - last_timestamp) * speed_flt;
 499
 500         if (!engine_init_called) {
 501                 const double e = elapsed + double (last_ltc_frame - sess_pos);
 502                 t0 = t1;
 503                 t1 += b * e + e2;
 504                 e2 += c * e;
 505                 speed_flt = (t1 - t0) / double(session.engine().frames_per_cycle());
 506                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC engine DLL t0:%1 t1:%2 err:%3 spd:%4 ddt:%5\n", t0, t1, e, speed_flt, e2 - session.engine().frames_per_cycle() ));
 507         } else {
 508                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC adjusting elapsed (no DLL) from %1 by %2\n", elapsed, (2 * nframes * ltc_speed)));
 509                 speed_flt = 0;
 510                 elapsed += 2.0 * nframes * ltc_speed; /* see note above */
 511         }
 512
 513         pos = last_ltc_frame + rint(elapsed);
 514         speed = speed_flt;
 515         current_delta = (pos - sess_pos);
 516
 517         if (((pos < 0) || (labs(current_delta) > 2 * session.frame_rate()))) {
 518                 DEBUG_TRACE (DEBUG::LTC, string_compose ("LTC large drift: %1\n", current_delta));
 519                 reset();
 520                 speed = 0;
 521                 pos = session.transport_frame();
 522                 return true;
 523         }
 524
 525         DEBUG_TRACE (DEBUG::LTC, string_compose ("LTCsync spd: %1 pos: %2 | last-pos: %3 elapsed: %4 delta: %5\n",
 526                                                  speed, pos, last_ltc_frame, elapsed, current_delta));
 527
 528         /* provide a .1% deadzone to lock the speed */
 529         if (fabs(speed - 1.0) <= 0.001) {
 530                 speed = 1.0;
 531         }
 532
 533         return true;
 534 }
 535
 536 Timecode::TimecodeFormat
 537 LTC_Slave::apparent_timecode_format () const
 538 {
 539         if      (timecode.rate == 24 && !timecode.drop)
 540                 return timecode_24;
 541         else if (timecode.rate == 25 && !timecode.drop)
 542                 return timecode_25;
 543         else if (rint(timecode.rate * 100) == 2997 && !timecode.drop)
 544                 return (Config->get_timecode_source_2997() ? timecode_2997000 : timecode_2997);
 545         else if (rint(timecode.rate * 100) == 2997 &&  timecode.drop)
 546                 return (Config->get_timecode_source_2997() ? timecode_2997000drop : timecode_2997drop);
 547         else if (timecode.rate == 30 &&  timecode.drop)
 548                 return timecode_2997drop; // timecode_30drop; // LTC counting to 30 frames w/DF *means* 29.97 df
 549         else if (timecode.rate == 30 && !timecode.drop)
 550                 return timecode_30;
 551
 552         /* XXX - unknown timecode format */
 553         return session.config.get_timecode_format();
 554 }
 555
 556 std::string
 557 LTC_Slave::approximate_current_position() const
 558 {
 559         if (last_timestamp == 0) {
 560                 return " \u2012\u2012:\u2012\u2012:\u2012\u2012:\u2012\u2012";
 561         }
 562         return Timecode::timecode_format_time(timecode);
 563 }
 564
 565 std::string
 566 LTC_Slave::approximate_current_delta() const
 567 {
 568         char delta[80];
 569         if (last_timestamp == 0 || engine_dll_initstate == 0) {
 570                 snprintf(delta, sizeof(delta), "\u2012\u2012\u2012\u2012");
 571         } else if ((monotonic_cnt - last_timestamp) > 2 * frames_per_ltc_frame) {
 572                 snprintf(delta, sizeof(delta), _("flywheel"));
 573         } else {
 574                 snprintf(delta, sizeof(delta), "\u0394<span foreground=\"green\" face=\"monospace\" >%s%s%" PRIi64 "</span> sm",
 575                                 LEADINGZERO(abs(current_delta)), PLUSMINUS(-current_delta), abs(current_delta));
 576         }
 577         return std::string(delta);
 578 }