src/wx/film_viewer.cc

   1 /*
   2     Copyright (C) 2012-2018 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of DCP-o-matic.
   5
   6     DCP-o-matic is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     DCP-o-matic is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21 /** @file  src/film_viewer.cc
  22  *  @brief A wx widget to view a preview of a Film.
  23  */
  24
  25 #include "film_viewer.h"
  26 #include "playhead_to_timecode_dialog.h"
  27 #include "playhead_to_frame_dialog.h"
  28 #include "wx_util.h"
  29 #include "closed_captions_dialog.h"
  30 #include "lib/film.h"
  31 #include "lib/ratio.h"
  32 #include "lib/util.h"
  33 #include "lib/job_manager.h"
  34 #include "lib/image.h"
  35 #include "lib/exceptions.h"
  36 #include "lib/examine_content_job.h"
  37 #include "lib/filter.h"
  38 #include "lib/player.h"
  39 #include "lib/player_video.h"
  40 #include "lib/video_content.h"
  41 #include "lib/video_decoder.h"
  42 #include "lib/timer.h"
  43 #include "lib/butler.h"
  44 #include "lib/log.h"
  45 #include "lib/config.h"
  46 extern "C" {
  47 #include <libavutil/pixfmt.h>
  48 }
  49 #include <dcp/exceptions.h>
  50 #include <wx/tglbtn.h>
  51 #include <iostream>
  52 #include <iomanip>
  53
  54 using std::string;
  55 using std::pair;
  56 using std::min;
  57 using std::max;
  58 using std::cout;
  59 using std::list;
  60 using std::bad_alloc;
  61 using std::make_pair;
  62 using std::exception;
  63 using boost::shared_ptr;
  64 using boost::dynamic_pointer_cast;
  65 using boost::weak_ptr;
  66 using boost::optional;
  67 using dcp::Size;
  68
  69 static
  70 int
  71 rtaudio_callback (void* out, void *, unsigned int frames, double, RtAudioStreamStatus, void* data)
  72 {
  73         return reinterpret_cast<FilmViewer*>(data)->audio_callback (out, frames);
  74 }
  75
  76 FilmViewer::FilmViewer (wxWindow* p)
  77         : _panel (new wxPanel (p))
  78         , _coalesce_player_changes (false)
  79         , _audio (DCPOMATIC_RTAUDIO_API)
  80         , _audio_channels (0)
  81         , _audio_block_size (1024)
  82         , _playing (false)
  83         , _latency_history_count (0)
  84         , _dropped (0)
  85         , _closed_captions_dialog (new ClosedCaptionsDialog(p))
  86         , _outline_content (false)
  87         , _eyes (EYES_LEFT)
  88 #ifdef DCPOMATIC_VARIANT_SWAROOP
  89         , _in_watermark (false)
  90 #endif
  91 {
  92 #ifndef __WXOSX__
  93         _panel->SetDoubleBuffered (true);
  94 #endif
  95
  96         _panel->SetBackgroundStyle (wxBG_STYLE_PAINT);
  97         _panel->SetBackgroundColour (*wxBLACK);
  98
  99         _panel->Bind (wxEVT_PAINT, boost::bind (&FilmViewer::paint_panel, this));
 100         _panel->Bind (wxEVT_SIZE,  boost::bind (&FilmViewer::panel_sized, this, _1));
 101         _timer.Bind  (wxEVT_TIMER, boost::bind (&FilmViewer::timer, this));
 102
 103         set_film (shared_ptr<Film> ());
 104
 105         _config_changed_connection = Config::instance()->Changed.connect (bind (&FilmViewer::config_changed, this, _1));
 106         config_changed (Config::SOUND_OUTPUT);
 107 }
 108
 109 FilmViewer::~FilmViewer ()
 110 {
 111         stop ();
 112 }
 113
 114 void
 115 FilmViewer::set_film (shared_ptr<Film> film)
 116 {
 117         if (_film == film) {
 118                 return;
 119         }
 120
 121         _film = film;
 122
 123         FilmChanged ();
 124
 125         _frame.reset ();
 126         _closed_captions_dialog->clear ();
 127
 128         if (!_film) {
 129                 _player.reset ();
 130                 recreate_butler ();
 131                 _frame.reset ();
 132                 refresh_panel ();
 133                 return;
 134         }
 135
 136         try {
 137                 _player.reset (new Player (_film, _film->playlist ()));
 138                 _player->set_fast ();
 139                 if (_dcp_decode_reduction) {
 140                         _player->set_dcp_decode_reduction (_dcp_decode_reduction);
 141                 }
 142         } catch (bad_alloc) {
 143                 error_dialog (_panel, _("There is not enough free memory to do that."));
 144                 _film.reset ();
 145                 return;
 146         }
 147
 148         _player->set_always_burn_open_subtitles ();
 149         _player->set_play_referenced ();
 150
 151         _film->Change.connect (boost::bind (&FilmViewer::film_change, this, _1, _2));
 152         _player->Change.connect (boost::bind (&FilmViewer::player_change, this, _1, _2, _3));
 153
 154         /* Keep about 1 second's worth of history samples */
 155         _latency_history_count = _film->audio_frame_rate() / _audio_block_size;
 156
 157         recreate_butler ();
 158
 159         calculate_sizes ();
 160         slow_refresh ();
 161 }
 162
 163 void
 164 FilmViewer::recreate_butler ()
 165 {
 166         bool const was_running = stop ();
 167         _butler.reset ();
 168
 169         if (!_film) {
 170                 return;
 171         }
 172
 173         AudioMapping map = AudioMapping (_film->audio_channels(), _audio_channels);
 174
 175         if (_audio_channels != 2 || _film->audio_channels() < 3) {
 176                 for (int i = 0; i < min (_film->audio_channels(), _audio_channels); ++i) {
 177                         map.set (i, i, 1);
 178                 }
 179         } else {
 180                 /* Special case: stereo output, at least 3 channel input.
 181                    Map so that Lt = L(-3dB) + Ls(-3dB) + C(-6dB) + Lfe(-10dB)
 182                                Rt = R(-3dB) + Rs(-3dB) + C(-6dB) + Lfe(-10dB)
 183                 */
 184                 map.set (dcp::LEFT,   0, 1 / sqrt(2)); // L -> Lt
 185                 map.set (dcp::RIGHT,  1, 1 / sqrt(2)); // R -> Rt
 186                 map.set (dcp::CENTRE, 0, 1 / 2.0); // C -> Lt
 187                 map.set (dcp::CENTRE, 1, 1 / 2.0); // C -> Rt
 188                 map.set (dcp::LFE,    0, 1 / sqrt(10)); // Lfe -> Lt
 189                 map.set (dcp::LFE,    1, 1 / sqrt(10)); // Lfe -> Rt
 190                 map.set (dcp::LS,     0, 1 / sqrt(2)); // Ls -> Lt
 191                 map.set (dcp::RS,     1, 1 / sqrt(2)); // Rs -> Rt
 192         }
 193
 194         _butler.reset (new Butler (_player, _film->log(), map, _audio_channels));
 195         if (!Config::instance()->sound() && !_audio.isStreamOpen()) {
 196                 _butler->disable_audio ();
 197         }
 198
 199         _closed_captions_dialog->set_butler (_butler);
 200
 201         if (was_running) {
 202                 start ();
 203         }
 204 }
 205
 206 void
 207 FilmViewer::refresh_panel ()
 208 {
 209         _panel->Refresh ();
 210         _panel->Update ();
 211 }
 212
 213 void
 214 FilmViewer::get ()
 215 {
 216         DCPOMATIC_ASSERT (_butler);
 217
 218         do {
 219                 Butler::Error e;
 220                 _player_video = _butler->get_video (&e);
 221                 if (!_player_video.first && e == Butler::AGAIN) {
 222                         signal_manager->when_idle (boost::bind(&FilmViewer::get, this));
 223                         return;
 224                 }
 225         } while (
 226                 _player_video.first &&
 227                 _film->three_d() &&
 228                 (_eyes != _player_video.first->eyes())
 229                 );
 230
 231         _butler->rethrow ();
 232
 233         display_player_video ();
 234 }
 235
 236 void
 237 FilmViewer::display_player_video ()
 238 {
 239         if (!_player_video.first) {
 240                 _frame.reset ();
 241                 refresh_panel ();
 242                 return;
 243         }
 244
 245         if (_playing && (time() - _player_video.second) > one_video_frame()) {
 246                 /* Too late; just drop this frame before we try to get its image (which will be the time-consuming
 247                    part if this frame is J2K).
 248                 */
 249                 _video_position = _player_video.second;
 250                 ++_dropped;
 251                 return;
 252         }
 253
 254         /* In an ideal world, what we would do here is:
 255          *
 256          * 1. convert to XYZ exactly as we do in the DCP creation path.
 257          * 2. convert back to RGB for the preview display, compensating
 258          *    for the monitor etc. etc.
 259          *
 260          * but this is inefficient if the source is RGB.  Since we don't
 261          * (currently) care too much about the precise accuracy of the preview's
 262          * colour mapping (and we care more about its speed) we try to short-
 263          * circuit this "ideal" situation in some cases.
 264          *
 265          * The content's specified colour conversion indicates the colourspace
 266          * which the content is in (according to the user).
 267          *
 268          * PlayerVideo::image (bound to PlayerVideo::always_rgb) will take the source
 269          * image and convert it (from whatever the user has said it is) to RGB.
 270          */
 271
 272         _frame = _player_video.first->image (
 273                 bind (&Log::dcp_log, _film->log().get(), _1, _2),
 274                 bind (&PlayerVideo::always_rgb, _1),
 275                 false, true
 276                 );
 277
 278         ImageChanged (_player_video.first);
 279
 280         _video_position = _player_video.second;
 281         _inter_position = _player_video.first->inter_position ();
 282         _inter_size = _player_video.first->inter_size ();
 283
 284         refresh_panel ();
 285
 286         _closed_captions_dialog->update (time());
 287 }
 288
 289 void
 290 FilmViewer::timer ()
 291 {
 292         if (!_film || !_playing) {
 293                 return;
 294         }
 295
 296         get ();
 297         PositionChanged ();
 298         DCPTime const next = _video_position + one_video_frame();
 299
 300         if (next >= _film->length()) {
 301                 stop ();
 302         }
 303
 304         _timer.Start (max ((next.seconds() - time().seconds()) * 1000, 1.0), wxTIMER_ONE_SHOT);
 305
 306         if (_butler) {
 307                 _butler->rethrow ();
 308         }
 309 }
 310
 311 void
 312 FilmViewer::paint_panel ()
 313 {
 314         wxPaintDC dc (_panel);
 315
 316         if (!_frame || !_film || !_out_size.width || !_out_size.height || _out_size != _frame->size()) {
 317                 dc.Clear ();
 318 #ifdef DCPOMATIC_VARIANT_SWAROOP
 319                 optional<boost::filesystem::path> bg = Config::instance()->player_background_image();
 320                 if (bg) {
 321                         wxImage image (std_to_wx(bg->string()));
 322                         wxBitmap bitmap (image);
 323                         dc.DrawBitmap (bitmap, max(0, (_panel_size.width - image.GetSize().GetWidth()) / 2), max(0, (_panel_size.height - image.GetSize().GetHeight()) / 2));
 324                 }
 325 #endif
 326                 return;
 327         }
 328
 329         wxImage frame (_out_size.width, _out_size.height, _frame->data()[0], true);
 330         wxBitmap frame_bitmap (frame);
 331         dc.DrawBitmap (frame_bitmap, 0, max(0, (_panel_size.height - _out_size.height) / 2));
 332
 333 #ifdef DCPOMATIC_VARIANT_SWAROOP
 334         DCPTime const period = DCPTime::from_seconds(Config::instance()->player_watermark_period() * 60);
 335         int64_t n = _video_position.get() / period.get();
 336         DCPTime from(n * period.get());
 337         DCPTime to = from + DCPTime::from_seconds(Config::instance()->player_watermark_duration() / 1000.0);
 338         if (from <= _video_position && _video_position <= to) {
 339                 if (!_in_watermark) {
 340                         _in_watermark = true;
 341                         _watermark_x = rand() % _panel_size.width;
 342                         _watermark_y = rand() % _panel_size.height;
 343                 }
 344                 dc.SetTextForeground(*wxWHITE);
 345                 dc.DrawText(std_to_wx(Config::instance()->player_watermark_theatre()), _watermark_x, _watermark_y);
 346         } else {
 347                 _in_watermark = false;
 348         }
 349 #endif
 350
 351         if (_out_size.width < _panel_size.width) {
 352                 wxPen p (_panel->GetParent()->GetBackgroundColour());
 353                 wxBrush b (_panel->GetParent()->GetBackgroundColour());
 354                 dc.SetPen (p);
 355                 dc.SetBrush (b);
 356                 dc.DrawRectangle (_out_size.width, 0, _panel_size.width - _out_size.width, _panel_size.height);
 357         }
 358
 359         if (_out_size.height < _panel_size.height) {
 360                 wxPen p (_panel->GetParent()->GetBackgroundColour());
 361                 wxBrush b (_panel->GetParent()->GetBackgroundColour());
 362                 dc.SetPen (p);
 363                 dc.SetBrush (b);
 364                 int const gap = (_panel_size.height - _out_size.height) / 2;
 365                 dc.DrawRectangle (0, 0, _panel_size.width, gap);
 366                 dc.DrawRectangle (0, gap + _out_size.height, _panel_size.width, gap);
 367         }
 368
 369         if (_outline_content) {
 370                 wxPen p (wxColour (255, 0, 0), 2);
 371                 dc.SetPen (p);
 372                 dc.SetBrush (*wxTRANSPARENT_BRUSH);
 373                 dc.DrawRectangle (_inter_position.x, _inter_position.y, _inter_size.width, _inter_size.height);
 374         }
 375 }
 376
 377 void
 378 FilmViewer::set_outline_content (bool o)
 379 {
 380         _outline_content = o;
 381         refresh_panel ();
 382 }
 383
 384 void
 385 FilmViewer::set_eyes (Eyes e)
 386 {
 387         _eyes = e;
 388         slow_refresh ();
 389 }
 390
 391 void
 392 FilmViewer::panel_sized (wxSizeEvent& ev)
 393 {
 394         _panel_size.width = ev.GetSize().GetWidth();
 395         _panel_size.height = ev.GetSize().GetHeight();
 396
 397         calculate_sizes ();
 398         if (!quick_refresh()) {
 399                 slow_refresh ();
 400         }
 401         PositionChanged ();
 402 }
 403
 404 void
 405 FilmViewer::calculate_sizes ()
 406 {
 407         if (!_film || !_player) {
 408                 return;
 409         }
 410
 411         Ratio const * container = _film->container ();
 412
 413         float const panel_ratio = _panel_size.ratio ();
 414         float const film_ratio = container ? container->ratio () : 1.78;
 415
 416         if (panel_ratio < film_ratio) {
 417                 /* panel is less widscreen than the film; clamp width */
 418                 _out_size.width = _panel_size.width;
 419                 _out_size.height = lrintf (_out_size.width / film_ratio);
 420         } else {
 421                 /* panel is more widescreen than the film; clamp height */
 422                 _out_size.height = _panel_size.height;
 423                 _out_size.width = lrintf (_out_size.height * film_ratio);
 424         }
 425
 426         /* Catch silly values */
 427         _out_size.width = max (64, _out_size.width);
 428         _out_size.height = max (64, _out_size.height);
 429
 430         _player->set_video_container_size (_out_size);
 431 }
 432
 433 void
 434 FilmViewer::start ()
 435 {
 436         if (!_film) {
 437                 return;
 438         }
 439
 440         optional<bool> v = PlaybackPermitted ();
 441         if (v && !*v) {
 442                 /* Computer says no */
 443                 return;
 444         }
 445
 446         if (_audio.isStreamOpen()) {
 447                 _audio.setStreamTime (_video_position.seconds());
 448                 _audio.startStream ();
 449         }
 450
 451         _playing = true;
 452         _dropped = 0;
 453         timer ();
 454         Started (position());
 455 }
 456
 457 bool
 458 FilmViewer::stop ()
 459 {
 460         if (_audio.isStreamRunning()) {
 461                 /* stop stream and discard any remaining queued samples */
 462                 _audio.abortStream ();
 463         }
 464
 465         if (!_playing) {
 466                 return false;
 467         }
 468
 469         _playing = false;
 470         Stopped (position());
 471         return true;
 472 }
 473
 474 void
 475 FilmViewer::player_change (ChangeType type, int property, bool frequent)
 476 {
 477         if (type != CHANGE_TYPE_DONE || frequent) {
 478                 return;
 479         }
 480
 481         if (_coalesce_player_changes) {
 482                 _pending_player_changes.push_back (property);
 483                 return;
 484         }
 485
 486         calculate_sizes ();
 487         bool refreshed = false;
 488         if (
 489                 property == VideoContentProperty::CROP ||
 490                 property == VideoContentProperty::SCALE ||
 491                 property == VideoContentProperty::FADE_IN ||
 492                 property == VideoContentProperty::FADE_OUT ||
 493                 property == VideoContentProperty::COLOUR_CONVERSION ||
 494                 property == PlayerProperty::VIDEO_CONTAINER_SIZE ||
 495                 property == PlayerProperty::FILM_CONTAINER
 496                 ) {
 497                 refreshed = quick_refresh ();
 498         }
 499
 500         if (!refreshed) {
 501                 slow_refresh ();
 502         }
 503         PositionChanged ();
 504 }
 505
 506 void
 507 FilmViewer::film_change (ChangeType type, Film::Property p)
 508 {
 509         if (type == CHANGE_TYPE_DONE && p == Film::AUDIO_CHANNELS) {
 510                 recreate_butler ();
 511         }
 512 }
 513
 514 /** Re-get the current frame slowly by seeking */
 515 void
 516 FilmViewer::slow_refresh ()
 517 {
 518         seek (_video_position, true);
 519 }
 520
 521 /** Try to re-get the current frame quickly by resetting the metadata
 522  *  in the PlayerVideo that we used last time.
 523  *  @return true if this was possible, false if not.
 524  */
 525 bool
 526 FilmViewer::quick_refresh ()
 527 {
 528         if (!_player_video.first) {
 529                 return false;
 530         }
 531
 532         if (!_player_video.first->reset_metadata (_player->video_container_size(), _film->frame_size())) {
 533                 return false;
 534         }
 535
 536         display_player_video ();
 537         return true;
 538 }
 539
 540 void
 541 FilmViewer::seek (shared_ptr<Content> content, ContentTime t, bool accurate)
 542 {
 543         optional<DCPTime> dt = _player->content_time_to_dcp (content, t);
 544         if (dt) {
 545                 seek (*dt, accurate);
 546         }
 547 }
 548
 549 void
 550 FilmViewer::set_coalesce_player_changes (bool c)
 551 {
 552         _coalesce_player_changes = c;
 553
 554         if (!c) {
 555                 BOOST_FOREACH (int i, _pending_player_changes) {
 556                         player_change (CHANGE_TYPE_DONE, i, false);
 557                 }
 558                 _pending_player_changes.clear ();
 559         }
 560 }
 561
 562 void
 563 FilmViewer::seek (DCPTime t, bool accurate)
 564 {
 565         if (!_butler) {
 566                 return;
 567         }
 568
 569         if (t < DCPTime ()) {
 570                 t = DCPTime ();
 571         }
 572
 573         if (t >= _film->length ()) {
 574                 t = _film->length ();
 575         }
 576
 577         bool const was_running = stop ();
 578
 579         _closed_captions_dialog->clear ();
 580         _butler->seek (t, accurate);
 581         get ();
 582
 583         if (was_running) {
 584                 start ();
 585         }
 586
 587         PositionChanged ();
 588         Seeked (position());
 589 }
 590
 591 void
 592 FilmViewer::config_changed (Config::Property p)
 593 {
 594 #ifdef DCPOMATIC_VARIANT_SWAROOP
 595         if (p == Config::PLAYER_BACKGROUND_IMAGE) {
 596                 refresh_panel ();
 597                 return;
 598         }
 599 #endif
 600
 601         if (p != Config::SOUND && p != Config::SOUND_OUTPUT) {
 602                 return;
 603         }
 604
 605         if (_audio.isStreamOpen ()) {
 606                 _audio.closeStream ();
 607         }
 608
 609         if (Config::instance()->sound() && _audio.getDeviceCount() > 0) {
 610                 unsigned int st = 0;
 611                 if (Config::instance()->sound_output()) {
 612                         while (st < _audio.getDeviceCount()) {
 613                                 if (_audio.getDeviceInfo(st).name == Config::instance()->sound_output().get()) {
 614                                         break;
 615                                 }
 616                                 ++st;
 617                         }
 618                         if (st == _audio.getDeviceCount()) {
 619                                 st = _audio.getDefaultOutputDevice();
 620                         }
 621                 } else {
 622                         st = _audio.getDefaultOutputDevice();
 623                 }
 624
 625                 _audio_channels = _audio.getDeviceInfo(st).outputChannels;
 626
 627                 RtAudio::StreamParameters sp;
 628                 sp.deviceId = st;
 629                 sp.nChannels = _audio_channels;
 630                 sp.firstChannel = 0;
 631                 try {
 632                         _audio.openStream (&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this);
 633 #ifdef DCPOMATIC_USE_RTERROR
 634                 } catch (RtError& e) {
 635 #else
 636                 } catch (RtAudioError& e) {
 637 #endif
 638                         error_dialog (
 639                                 _panel,
 640                                 _("Could not set up audio output.  There will be no audio during the preview."), std_to_wx(e.what())
 641                                 );
 642                 }
 643                 recreate_butler ();
 644
 645         } else {
 646                 _audio_channels = 0;
 647                 recreate_butler ();
 648         }
 649 }
 650
 651 DCPTime
 652 FilmViewer::uncorrected_time () const
 653 {
 654         if (_audio.isStreamRunning ()) {
 655                 return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime());
 656         }
 657
 658         return _video_position;
 659 }
 660
 661 DCPTime
 662 FilmViewer::time () const
 663 {
 664         if (_audio.isStreamRunning ()) {
 665                 return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime ()) -
 666                         DCPTime::from_frames (average_latency(), _film->audio_frame_rate());
 667         }
 668
 669         return _video_position;
 670 }
 671
 672 int
 673 FilmViewer::audio_callback (void* out_p, unsigned int frames)
 674 {
 675         while (true) {
 676                 optional<DCPTime> t = _butler->get_audio (reinterpret_cast<float*> (out_p), frames);
 677                 if (!t || DCPTime(uncorrected_time() - *t) < one_video_frame()) {
 678                         /* There was an underrun or this audio is on time; carry on */
 679                         break;
 680                 }
 681                 /* The audio we just got was (very) late; drop it and get some more. */
 682         }
 683
 684         boost::mutex::scoped_lock lm (_latency_history_mutex, boost::try_to_lock);
 685         if (lm) {
 686                 _latency_history.push_back (_audio.getStreamLatency ());
 687                 if (_latency_history.size() > static_cast<size_t> (_latency_history_count)) {
 688                         _latency_history.pop_front ();
 689                 }
 690         }
 691
 692         return 0;
 693 }
 694
 695 Frame
 696 FilmViewer::average_latency () const
 697 {
 698         boost::mutex::scoped_lock lm (_latency_history_mutex);
 699         if (_latency_history.empty()) {
 700                 return 0;
 701         }
 702
 703         Frame total = 0;
 704         BOOST_FOREACH (Frame i, _latency_history) {
 705                 total += i;
 706         }
 707
 708         return total / _latency_history.size();
 709 }
 710
 711 void
 712 FilmViewer::set_dcp_decode_reduction (optional<int> reduction)
 713 {
 714         _dcp_decode_reduction = reduction;
 715         if (_player) {
 716                 _player->set_dcp_decode_reduction (reduction);
 717         }
 718 }
 719
 720 optional<int>
 721 FilmViewer::dcp_decode_reduction () const
 722 {
 723         return _dcp_decode_reduction;
 724 }
 725
 726 DCPTime
 727 FilmViewer::one_video_frame () const
 728 {
 729         return DCPTime::from_frames (1, _film->video_frame_rate());
 730 }
 731
 732 /** Open a dialog box showing our film's closed captions */
 733 void
 734 FilmViewer::show_closed_captions ()
 735 {
 736         _closed_captions_dialog->Show();
 737 }
 738
 739 void
 740 FilmViewer::seek_by (DCPTime by, bool accurate)
 741 {
 742         seek (_video_position + by, accurate);
 743 }