src/wx/film_viewer.cc

   1 /*
   2     Copyright (C) 2012-2019 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 #include "lib/compose.hpp"
  47 #include "lib/dcpomatic_log.h"
  48 extern "C" {
  49 #include <libavutil/pixfmt.h>
  50 }
  51 #include <dcp/exceptions.h>
  52 #include <wx/tglbtn.h>
  53 #include <iostream>
  54 #include <iomanip>
  55
  56 using std::string;
  57 using std::pair;
  58 using std::min;
  59 using std::max;
  60 using std::cout;
  61 using std::list;
  62 using std::bad_alloc;
  63 using std::make_pair;
  64 using std::exception;
  65 using boost::shared_ptr;
  66 using boost::dynamic_pointer_cast;
  67 using boost::weak_ptr;
  68 using boost::optional;
  69 using dcp::Size;
  70
  71 static
  72 int
  73 rtaudio_callback (void* out, void *, unsigned int frames, double, RtAudioStreamStatus, void* data)
  74 {
  75         return reinterpret_cast<FilmViewer*>(data)->audio_callback (out, frames);
  76 }
  77
  78 FilmViewer::FilmViewer (wxWindow* p)
  79         : _panel (new wxPanel (p))
  80         , _coalesce_player_changes (false)
  81         , _audio (DCPOMATIC_RTAUDIO_API)
  82         , _audio_channels (0)
  83         , _audio_block_size (1024)
  84         , _playing (false)
  85         , _latency_history_count (0)
  86         , _dropped (0)
  87         , _closed_captions_dialog (new ClosedCaptionsDialog(p, this))
  88         , _outline_content (false)
  89         , _eyes (EYES_LEFT)
  90         , _pad_black (false)
  91 #ifdef DCPOMATIC_VARIANT_SWAROOP
  92         , _in_watermark (false)
  93         , _background_image (false)
  94 #endif
  95 {
  96 #ifndef __WXOSX__
  97         _panel->SetDoubleBuffered (true);
  98 #endif
  99
 100         _panel->SetBackgroundStyle (wxBG_STYLE_PAINT);
 101         _panel->SetBackgroundColour (*wxBLACK);
 102
 103         _panel->Bind (wxEVT_PAINT, boost::bind (&FilmViewer::paint_panel, this));
 104         _panel->Bind (wxEVT_SIZE,  boost::bind (&FilmViewer::panel_sized, this, _1));
 105         _timer.Bind  (wxEVT_TIMER, boost::bind (&FilmViewer::timer, this));
 106
 107         set_film (shared_ptr<Film> ());
 108
 109         _config_changed_connection = Config::instance()->Changed.connect (bind (&FilmViewer::config_changed, this, _1));
 110         config_changed (Config::SOUND_OUTPUT);
 111 }
 112
 113 FilmViewer::~FilmViewer ()
 114 {
 115         stop ();
 116 }
 117
 118 void
 119 FilmViewer::set_film (shared_ptr<Film> film)
 120 {
 121         if (_film == film) {
 122                 return;
 123         }
 124
 125         _film = film;
 126         _video_position = DCPTime ();
 127         _player_video.first.reset ();
 128         _player_video.second = DCPTime ();
 129
 130         _frame.reset ();
 131         _closed_captions_dialog->clear ();
 132
 133         if (!_film) {
 134                 _player.reset ();
 135                 recreate_butler ();
 136                 _frame.reset ();
 137                 refresh_panel ();
 138                 return;
 139         }
 140
 141         try {
 142                 _player.reset (new Player (_film, _film->playlist ()));
 143                 _player->set_fast ();
 144                 if (_dcp_decode_reduction) {
 145                         _player->set_dcp_decode_reduction (_dcp_decode_reduction);
 146                 }
 147         } catch (bad_alloc &) {
 148                 error_dialog (_panel, _("There is not enough free memory to do that."));
 149                 _film.reset ();
 150                 return;
 151         }
 152
 153         _player->set_always_burn_open_subtitles ();
 154         _player->set_play_referenced ();
 155
 156         _film->Change.connect (boost::bind (&FilmViewer::film_change, this, _1, _2));
 157         _player->Change.connect (boost::bind (&FilmViewer::player_change, this, _1, _2, _3));
 158
 159         /* Keep about 1 second's worth of history samples */
 160         _latency_history_count = _film->audio_frame_rate() / _audio_block_size;
 161
 162         recreate_butler ();
 163
 164         calculate_sizes ();
 165         slow_refresh ();
 166 }
 167
 168 void
 169 FilmViewer::recreate_butler ()
 170 {
 171         bool const was_running = stop ();
 172         _butler.reset ();
 173
 174         if (!_film) {
 175                 return;
 176         }
 177
 178         AudioMapping map = AudioMapping (_film->audio_channels(), _audio_channels);
 179
 180         if (_audio_channels != 2 || _film->audio_channels() < 3) {
 181                 for (int i = 0; i < min (_film->audio_channels(), _audio_channels); ++i) {
 182                         map.set (i, i, 1);
 183                 }
 184         } else {
 185                 /* Special case: stereo output, at least 3 channel input.
 186                    Map so that Lt = L(-3dB) + Ls(-3dB) + C(-6dB) + Lfe(-10dB)
 187                                Rt = R(-3dB) + Rs(-3dB) + C(-6dB) + Lfe(-10dB)
 188                 */
 189                 map.set (dcp::LEFT,   0, 1 / sqrt(2)); // L -> Lt
 190                 map.set (dcp::RIGHT,  1, 1 / sqrt(2)); // R -> Rt
 191                 map.set (dcp::CENTRE, 0, 1 / 2.0); // C -> Lt
 192                 map.set (dcp::CENTRE, 1, 1 / 2.0); // C -> Rt
 193                 map.set (dcp::LFE,    0, 1 / sqrt(10)); // Lfe -> Lt
 194                 map.set (dcp::LFE,    1, 1 / sqrt(10)); // Lfe -> Rt
 195                 map.set (dcp::LS,     0, 1 / sqrt(2)); // Ls -> Lt
 196                 map.set (dcp::RS,     1, 1 / sqrt(2)); // Rs -> Rt
 197         }
 198
 199         _butler.reset (new Butler(_player, map, _audio_channels, bind(&PlayerVideo::force, _1, AV_PIX_FMT_RGB24), false, true));
 200         if (!Config::instance()->sound() && !_audio.isStreamOpen()) {
 201                 _butler->disable_audio ();
 202         }
 203
 204         _closed_captions_dialog->set_film_and_butler (_film, _butler);
 205
 206         if (was_running) {
 207                 start ();
 208         }
 209 }
 210
 211 void
 212 FilmViewer::refresh_panel ()
 213 {
 214         _panel->Refresh ();
 215         _panel->Update ();
 216 }
 217
 218 void
 219 FilmViewer::get ()
 220 {
 221         DCPOMATIC_ASSERT (_butler);
 222
 223         do {
 224                 Butler::Error e;
 225                 _player_video = _butler->get_video (&e);
 226                 if (!_player_video.first && e == Butler::AGAIN) {
 227                         signal_manager->when_idle (boost::bind(&FilmViewer::get, this));
 228                         return;
 229                 }
 230         } while (
 231                 _player_video.first &&
 232                 _film->three_d() &&
 233                 _eyes != _player_video.first->eyes() &&
 234                 _player_video.first->eyes() != EYES_BOTH
 235                 );
 236
 237         try {
 238                 _butler->rethrow ();
 239         } catch (DecodeError& e) {
 240                 error_dialog (_panel, e.what());
 241         }
 242
 243         display_player_video ();
 244 }
 245
 246 void
 247 FilmViewer::display_player_video ()
 248 {
 249         if (!_player_video.first) {
 250                 _frame.reset ();
 251                 refresh_panel ();
 252                 return;
 253         }
 254
 255         if (_playing && (time() - _player_video.second) > one_video_frame()) {
 256                 /* Too late; just drop this frame before we try to get its image (which will be the time-consuming
 257                    part if this frame is J2K).
 258                 */
 259                 _video_position = _player_video.second;
 260                 ++_dropped;
 261                 return;
 262         }
 263
 264         /* In an ideal world, what we would do here is:
 265          *
 266          * 1. convert to XYZ exactly as we do in the DCP creation path.
 267          * 2. convert back to RGB for the preview display, compensating
 268          *    for the monitor etc. etc.
 269          *
 270          * but this is inefficient if the source is RGB.  Since we don't
 271          * (currently) care too much about the precise accuracy of the preview's
 272          * colour mapping (and we care more about its speed) we try to short-
 273          * circuit this "ideal" situation in some cases.
 274          *
 275          * The content's specified colour conversion indicates the colourspace
 276          * which the content is in (according to the user).
 277          *
 278          * PlayerVideo::image (bound to PlayerVideo::force) will take the source
 279          * image and convert it (from whatever the user has said it is) to RGB.
 280          */
 281
 282         _frame = _player_video.first->image (bind(&PlayerVideo::force, _1, AV_PIX_FMT_RGB24), false, true);
 283
 284         ImageChanged (_player_video.first);
 285
 286         _video_position = _player_video.second;
 287         _inter_position = _player_video.first->inter_position ();
 288         _inter_size = _player_video.first->inter_size ();
 289
 290         refresh_panel ();
 291
 292         _closed_captions_dialog->update (time());
 293 }
 294
 295 void
 296 FilmViewer::timer ()
 297 {
 298         if (!_film || !_playing) {
 299                 return;
 300         }
 301
 302         get ();
 303         PositionChanged ();
 304         DCPTime const next = _video_position + one_video_frame();
 305
 306         if (next >= _film->length()) {
 307                 stop ();
 308                 Finished ();
 309                 return;
 310         }
 311
 312         LOG_DEBUG_PLAYER("%1 -> %2; delay %3", next.seconds(), time().seconds(), max((next.seconds() - time().seconds()) * 1000, 1.0));
 313         _timer.Start (max ((next.seconds() - time().seconds()) * 1000, 1.0), wxTIMER_ONE_SHOT);
 314
 315         if (_butler) {
 316                 _butler->rethrow ();
 317         }
 318 }
 319
 320 bool
 321 #ifdef DCPOMATIC_VARIANT_SWAROOP
 322 FilmViewer::maybe_draw_background_image (wxPaintDC& dc)
 323 {
 324         optional<boost::filesystem::path> bg = Config::instance()->player_background_image();
 325         if (bg) {
 326                 wxImage image (std_to_wx(bg->string()));
 327                 wxBitmap bitmap (image);
 328                 dc.DrawBitmap (bitmap, max(0, (_panel_size.width - image.GetSize().GetWidth()) / 2), max(0, (_panel_size.height - image.GetSize().GetHeight()) / 2));
 329                 return true;
 330         }
 331
 332         return false;
 333 }
 334 #else
 335 FilmViewer::maybe_draw_background_image (wxPaintDC &)
 336 {
 337         return false;
 338 }
 339 #endif
 340
 341 void
 342 FilmViewer::paint_panel ()
 343 {
 344         wxPaintDC dc (_panel);
 345
 346 #ifdef DCPOMATIC_VARIANT_SWAROOP
 347         if (_background_image) {
 348                 dc.Clear ();
 349                 maybe_draw_background_image (dc);
 350                 return;
 351         }
 352 #endif
 353
 354         if (!_out_size.width || !_out_size.height || !_film || !_frame || _out_size != _frame->size()) {
 355                 dc.Clear ();
 356         } else {
 357
 358                 wxImage frame (_out_size.width, _out_size.height, _frame->data()[0], true);
 359                 wxBitmap frame_bitmap (frame);
 360                 dc.DrawBitmap (frame_bitmap, 0, max(0, (_panel_size.height - _out_size.height) / 2));
 361
 362 #ifdef DCPOMATIC_VARIANT_SWAROOP
 363                 DCPTime const period = DCPTime::from_seconds(Config::instance()->player_watermark_period() * 60);
 364                 int64_t n = _video_position.get() / period.get();
 365                 DCPTime from(n * period.get());
 366                 DCPTime to = from + DCPTime::from_seconds(Config::instance()->player_watermark_duration() / 1000.0);
 367                 if (from <= _video_position && _video_position <= to) {
 368                         if (!_in_watermark) {
 369                                 _in_watermark = true;
 370                                 _watermark_x = rand() % _panel_size.width;
 371                                 _watermark_y = rand() % _panel_size.height;
 372                         }
 373                         dc.SetTextForeground(*wxWHITE);
 374                         string wm = Config::instance()->player_watermark_theatre();
 375                         boost::posix_time::ptime t = boost::posix_time::second_clock::local_time();
 376                         wm += "\n" + boost::posix_time::to_iso_extended_string(t);
 377                         dc.DrawText(std_to_wx(wm), _watermark_x, _watermark_y);
 378                 } else {
 379                         _in_watermark = false;
 380                 }
 381 #endif
 382         }
 383
 384         if (_out_size.width < _panel_size.width) {
 385                 /* XXX: these colours are right for GNOME; may need adjusting for other OS */
 386                 wxPen   p (_pad_black ? wxColour(0, 0, 0) : wxColour(240, 240, 240));
 387                 wxBrush b (_pad_black ? wxColour(0, 0, 0) : wxColour(240, 240, 240));
 388                 dc.SetPen (p);
 389                 dc.SetBrush (b);
 390                 dc.DrawRectangle (_out_size.width, 0, _panel_size.width - _out_size.width, _panel_size.height);
 391         }
 392
 393         if (_out_size.height < _panel_size.height) {
 394                 wxPen   p (_pad_black ? wxColour(0, 0, 0) : wxColour(240, 240, 240));
 395                 wxBrush b (_pad_black ? wxColour(0, 0, 0) : wxColour(240, 240, 240));
 396                 dc.SetPen (p);
 397                 dc.SetBrush (b);
 398                 int const gap = (_panel_size.height - _out_size.height) / 2;
 399                 dc.DrawRectangle (0, 0, _panel_size.width, gap);
 400                 dc.DrawRectangle (0, gap + _out_size.height + 1, _panel_size.width, gap + 1);
 401         }
 402
 403         if (_outline_content) {
 404                 wxPen p (wxColour (255, 0, 0), 2);
 405                 dc.SetPen (p);
 406                 dc.SetBrush (*wxTRANSPARENT_BRUSH);
 407                 dc.DrawRectangle (_inter_position.x, _inter_position.y + (_panel_size.height - _out_size.height) / 2, _inter_size.width, _inter_size.height);
 408         }
 409 }
 410
 411 void
 412 FilmViewer::set_outline_content (bool o)
 413 {
 414         _outline_content = o;
 415         refresh_panel ();
 416 }
 417
 418 void
 419 FilmViewer::set_eyes (Eyes e)
 420 {
 421         _eyes = e;
 422         slow_refresh ();
 423 }
 424
 425 void
 426 FilmViewer::panel_sized (wxSizeEvent& ev)
 427 {
 428         _panel_size.width = ev.GetSize().GetWidth();
 429         _panel_size.height = ev.GetSize().GetHeight();
 430
 431         calculate_sizes ();
 432         if (!quick_refresh()) {
 433                 slow_refresh ();
 434         }
 435         PositionChanged ();
 436 }
 437
 438 void
 439 FilmViewer::calculate_sizes ()
 440 {
 441         if (!_film || !_player) {
 442                 return;
 443         }
 444
 445         Ratio const * container = _film->container ();
 446
 447         float const panel_ratio = _panel_size.ratio ();
 448         float const film_ratio = container ? container->ratio () : 1.78;
 449
 450         if (panel_ratio < film_ratio) {
 451                 /* panel is less widscreen than the film; clamp width */
 452                 _out_size.width = _panel_size.width;
 453                 _out_size.height = lrintf (_out_size.width / film_ratio);
 454         } else {
 455                 /* panel is more widescreen than the film; clamp height */
 456                 _out_size.height = _panel_size.height;
 457                 _out_size.width = lrintf (_out_size.height * film_ratio);
 458         }
 459
 460         /* Catch silly values */
 461         _out_size.width = max (64, _out_size.width);
 462         _out_size.height = max (64, _out_size.height);
 463
 464         _player->set_video_container_size (_out_size);
 465 }
 466
 467 void
 468 FilmViewer::start ()
 469 {
 470         if (!_film) {
 471                 return;
 472         }
 473
 474         optional<bool> v = PlaybackPermitted ();
 475         if (v && !*v) {
 476                 /* Computer says no */
 477                 return;
 478         }
 479
 480         if (_audio.isStreamOpen()) {
 481                 _audio.setStreamTime (_video_position.seconds());
 482                 _audio.startStream ();
 483         }
 484
 485         _playing = true;
 486         _dropped = 0;
 487         timer ();
 488         Started (position());
 489 }
 490
 491 bool
 492 FilmViewer::stop ()
 493 {
 494         if (_audio.isStreamRunning()) {
 495                 /* stop stream and discard any remaining queued samples */
 496                 _audio.abortStream ();
 497         }
 498
 499         if (!_playing) {
 500                 return false;
 501         }
 502
 503         _playing = false;
 504         Stopped (position());
 505         return true;
 506 }
 507
 508 void
 509 FilmViewer::player_change (ChangeType type, int property, bool frequent)
 510 {
 511         if (type != CHANGE_TYPE_DONE || frequent) {
 512                 return;
 513         }
 514
 515         if (_coalesce_player_changes) {
 516                 _pending_player_changes.push_back (property);
 517                 return;
 518         }
 519
 520         calculate_sizes ();
 521         bool refreshed = false;
 522         if (
 523                 property == VideoContentProperty::CROP ||
 524                 property == VideoContentProperty::SCALE ||
 525                 property == VideoContentProperty::FADE_IN ||
 526                 property == VideoContentProperty::FADE_OUT ||
 527                 property == VideoContentProperty::COLOUR_CONVERSION ||
 528                 property == PlayerProperty::VIDEO_CONTAINER_SIZE ||
 529                 property == PlayerProperty::FILM_CONTAINER
 530                 ) {
 531                 refreshed = quick_refresh ();
 532         }
 533
 534         if (!refreshed) {
 535                 slow_refresh ();
 536         }
 537         PositionChanged ();
 538 }
 539
 540 void
 541 FilmViewer::film_change (ChangeType type, Film::Property p)
 542 {
 543         if (type == CHANGE_TYPE_DONE && p == Film::AUDIO_CHANNELS) {
 544                 recreate_butler ();
 545         }
 546 }
 547
 548 /** Re-get the current frame slowly by seeking */
 549 void
 550 FilmViewer::slow_refresh ()
 551 {
 552         seek (_video_position, true);
 553 }
 554
 555 /** Try to re-get the current frame quickly by resetting the metadata
 556  *  in the PlayerVideo that we used last time.
 557  *  @return true if this was possible, false if not.
 558  */
 559 bool
 560 FilmViewer::quick_refresh ()
 561 {
 562         if (!_player_video.first) {
 563                 return false;
 564         }
 565
 566         if (!_player_video.first->reset_metadata (_film, _player->video_container_size(), _film->frame_size())) {
 567                 return false;
 568         }
 569
 570         display_player_video ();
 571         return true;
 572 }
 573
 574 void
 575 FilmViewer::seek (shared_ptr<Content> content, ContentTime t, bool accurate)
 576 {
 577         optional<DCPTime> dt = _player->content_time_to_dcp (content, t);
 578         if (dt) {
 579                 seek (*dt, accurate);
 580         }
 581 }
 582
 583 void
 584 FilmViewer::set_coalesce_player_changes (bool c)
 585 {
 586         _coalesce_player_changes = c;
 587
 588         if (!c) {
 589                 BOOST_FOREACH (int i, _pending_player_changes) {
 590                         player_change (CHANGE_TYPE_DONE, i, false);
 591                 }
 592                 _pending_player_changes.clear ();
 593         }
 594 }
 595
 596 void
 597 FilmViewer::seek (DCPTime t, bool accurate)
 598 {
 599         if (!_butler) {
 600                 return;
 601         }
 602
 603         if (t < DCPTime ()) {
 604                 t = DCPTime ();
 605         }
 606
 607         if (t >= _film->length ()) {
 608                 t = _film->length ();
 609         }
 610
 611         bool const was_running = stop ();
 612
 613         _closed_captions_dialog->clear ();
 614         _butler->seek (t, accurate);
 615         get ();
 616
 617         if (was_running) {
 618                 start ();
 619         }
 620
 621         PositionChanged ();
 622 }
 623
 624 void
 625 FilmViewer::config_changed (Config::Property p)
 626 {
 627 #ifdef DCPOMATIC_VARIANT_SWAROOP
 628         if (p == Config::PLAYER_BACKGROUND_IMAGE) {
 629                 refresh_panel ();
 630                 return;
 631         }
 632 #endif
 633
 634         if (p != Config::SOUND && p != Config::SOUND_OUTPUT) {
 635                 return;
 636         }
 637
 638         if (_audio.isStreamOpen ()) {
 639                 _audio.closeStream ();
 640         }
 641
 642         if (Config::instance()->sound() && _audio.getDeviceCount() > 0) {
 643                 unsigned int st = 0;
 644                 if (Config::instance()->sound_output()) {
 645                         while (st < _audio.getDeviceCount()) {
 646                                 if (_audio.getDeviceInfo(st).name == Config::instance()->sound_output().get()) {
 647                                         break;
 648                                 }
 649                                 ++st;
 650                         }
 651                         if (st == _audio.getDeviceCount()) {
 652                                 st = _audio.getDefaultOutputDevice();
 653                         }
 654                 } else {
 655                         st = _audio.getDefaultOutputDevice();
 656                 }
 657
 658                 _audio_channels = _audio.getDeviceInfo(st).outputChannels;
 659
 660                 RtAudio::StreamParameters sp;
 661                 sp.deviceId = st;
 662                 sp.nChannels = _audio_channels;
 663                 sp.firstChannel = 0;
 664                 try {
 665                         _audio.openStream (&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this);
 666 #ifdef DCPOMATIC_USE_RTERROR
 667                 } catch (RtError& e) {
 668 #else
 669                 } catch (RtAudioError& e) {
 670 #endif
 671                         error_dialog (
 672                                 _panel,
 673                                 _("Could not set up audio output.  There will be no audio during the preview."), std_to_wx(e.what())
 674                                 );
 675                 }
 676                 recreate_butler ();
 677
 678         } else {
 679                 _audio_channels = 0;
 680                 recreate_butler ();
 681         }
 682 }
 683
 684 DCPTime
 685 FilmViewer::uncorrected_time () const
 686 {
 687         if (_audio.isStreamRunning ()) {
 688                 return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime());
 689         }
 690
 691         return _video_position;
 692 }
 693
 694 DCPTime
 695 FilmViewer::time () const
 696 {
 697         if (_audio.isStreamRunning ()) {
 698                 return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime ()) -
 699                         DCPTime::from_frames (average_latency(), _film->audio_frame_rate());
 700         }
 701
 702         return _video_position;
 703 }
 704
 705 int
 706 FilmViewer::audio_callback (void* out_p, unsigned int frames)
 707 {
 708         while (true) {
 709                 optional<DCPTime> t = _butler->get_audio (reinterpret_cast<float*> (out_p), frames);
 710                 if (!t || DCPTime(uncorrected_time() - *t) < one_video_frame()) {
 711                         /* There was an underrun or this audio is on time; carry on */
 712                         break;
 713                 }
 714                 /* The audio we just got was (very) late; drop it and get some more. */
 715         }
 716
 717         boost::mutex::scoped_lock lm (_latency_history_mutex, boost::try_to_lock);
 718         if (lm) {
 719                 _latency_history.push_back (_audio.getStreamLatency ());
 720                 if (_latency_history.size() > static_cast<size_t> (_latency_history_count)) {
 721                         _latency_history.pop_front ();
 722                 }
 723         }
 724
 725         return 0;
 726 }
 727
 728 Frame
 729 FilmViewer::average_latency () const
 730 {
 731         boost::mutex::scoped_lock lm (_latency_history_mutex);
 732         if (_latency_history.empty()) {
 733                 return 0;
 734         }
 735
 736         Frame total = 0;
 737         BOOST_FOREACH (Frame i, _latency_history) {
 738                 total += i;
 739         }
 740
 741         return total / _latency_history.size();
 742 }
 743
 744 void
 745 FilmViewer::set_dcp_decode_reduction (optional<int> reduction)
 746 {
 747         _dcp_decode_reduction = reduction;
 748         if (_player) {
 749                 _player->set_dcp_decode_reduction (reduction);
 750         }
 751 }
 752
 753 optional<int>
 754 FilmViewer::dcp_decode_reduction () const
 755 {
 756         return _dcp_decode_reduction;
 757 }
 758
 759 DCPTime
 760 FilmViewer::one_video_frame () const
 761 {
 762         return DCPTime::from_frames (1, _film->video_frame_rate());
 763 }
 764
 765 /** Open a dialog box showing our film's closed captions */
 766 void
 767 FilmViewer::show_closed_captions ()
 768 {
 769         _closed_captions_dialog->Show();
 770 }
 771
 772 void
 773 FilmViewer::seek_by (DCPTime by, bool accurate)
 774 {
 775         seek (_video_position + by, accurate);
 776 }
 777
 778 void
 779 FilmViewer::set_pad_black (bool p)
 780 {
 781         _pad_black = p;
 782 }