git.sesse.net Git - nageru/blob - futatabi/player.cpp

   1 #include "player.h"
   2
   3 #include "clip_list.h"
   4 #include "defs.h"
   5 #include "flags.h"
   6 #include "frame_on_disk.h"
   7 #include "jpeg_frame_view.h"
   8 #include "shared/context.h"
   9 #include "shared/ffmpeg_raii.h"
  10 #include "shared/httpd.h"
  11 #include "shared/metrics.h"
  12 #include "shared/mux.h"
  13 #include "shared/timebase.h"
  14 #include "video_stream.h"
  15
  16 #include <algorithm>
  17 #include <chrono>
  18 #include <condition_variable>
  19 #include <movit/util.h>
  20 #include <mutex>
  21 #include <stdio.h>
  22 #include <thread>
  23 #include <vector>
  24
  25 using namespace std;
  26 using namespace std::chrono;
  27
  28 extern HTTPD *global_httpd;
  29
  30 void Player::thread_func(AVFormatContext *file_avctx)
  31 {
  32         pthread_setname_np(pthread_self(), "Player");
  33
  34         QSurface *surface = create_surface();
  35         QOpenGLContext *context = create_context(surface);
  36         if (!make_current(context, surface)) {
  37                 printf("oops\n");
  38                 exit(1);
  39         }
  40
  41         check_error();
  42
  43         // Create the VideoStream object, now that we have an OpenGL context.
  44         if (stream_output != NO_STREAM_OUTPUT) {
  45                 video_stream.reset(new VideoStream(file_avctx));
  46                 video_stream->start();
  47         }
  48
  49         check_error();
  50
  51         while (!should_quit) {
  52                 play_playlist_once();
  53                 if (done_callback != nullptr) {
  54                         done_callback();
  55                 }
  56         }
  57 }
  58
  59 namespace {
  60
  61 double calc_progress(const Clip &clip, int64_t pts)
  62 {
  63         return double(pts - clip.pts_in) / (clip.pts_out - clip.pts_in);
  64 }
  65
  66 void do_splice(const vector<ClipWithID> &new_list, size_t playing_index1, ssize_t playing_index2, vector<ClipWithID> *old_list)
  67 {
  68         assert(playing_index2 == -1 || size_t(playing_index2) == playing_index1 + 1);
  69
  70         // First see if we can do the simple thing; find an element in the new
  71         // list that we are already playing, which will serve as our splice point.
  72         int splice_start_new_list = -1;
  73         for (size_t clip_idx = 0; clip_idx < new_list.size(); ++clip_idx) {
  74                 if (new_list[clip_idx].id == (*old_list)[playing_index1].id) {
  75                         splice_start_new_list = clip_idx + 1;
  76                 } else if (playing_index2 != -1 && new_list[clip_idx].id == (*old_list)[playing_index2].id) {
  77                         splice_start_new_list = clip_idx + 1;
  78                 }
  79         }
  80         if (splice_start_new_list == -1) {
  81                 // OK, so the playing items are no longer in the new list. Most likely,
  82                 // that means we deleted some range that included them. But the ones
  83                 // before should stay put -- and we don't want to play them. So find
  84                 // the ones that we've already played, and ignore them. Hopefully,
  85                 // they're contiguous; the last one that's not seen will be our cut point.
  86                 //
  87                 // Keeping track of the playlist range explicitly in the UI would remove
  88                 // the need for these heuristics, but it would probably also mean we'd
  89                 // have to lock the playing clip, which sounds annoying.
  90                 unordered_map<uint64_t, size_t> played_ids;
  91                 for (size_t clip_idx = 0; clip_idx < playing_index1; ++old_list) {
  92                         played_ids.emplace((*old_list)[clip_idx].id, clip_idx);
  93                 }
  94                 for (size_t clip_idx = 0; clip_idx < new_list.size(); ++clip_idx) {
  95                         if (played_ids.count(new_list[clip_idx].id)) {
  96                                 splice_start_new_list = clip_idx + 1;
  97                         }
  98                 }
  99
 100                 if (splice_start_new_list == -1) {
 101                         // OK, we didn't find any matches; the lists are totally distinct.
 102                         // So probably the entire thing was deleted; leave it alone.
 103                         return;
 104                 }
 105         }
 106
 107         size_t splice_start_old_list = ((playing_index2 == -1) ? playing_index1 : playing_index2) + 1;
 108         old_list->erase(old_list->begin() + splice_start_old_list, old_list->end());
 109         old_list->insert(old_list->end(), new_list.begin() + splice_start_new_list, new_list.end());
 110 }
 111
 112 }  // namespace
 113
 114 void Player::play_playlist_once()
 115 {
 116         vector<ClipWithID> clip_list;
 117         bool clip_ready;
 118         steady_clock::time_point before_sleep = steady_clock::now();
 119
 120         // Wait until we're supposed to play something.
 121         {
 122                 unique_lock<mutex> lock(queue_state_mu);
 123                 playing = false;
 124                 clip_ready = new_clip_changed.wait_for(lock, milliseconds(100), [this] {
 125                         return should_quit || new_clip_ready;
 126                 });
 127                 if (should_quit) {
 128                         return;
 129                 }
 130                 if (clip_ready) {
 131                         new_clip_ready = false;
 132                         playing = true;
 133                         clip_list = move(queued_clip_list);
 134                         queued_clip_list.clear();
 135                         assert(!clip_list.empty());
 136                         assert(!splice_ready);  // This corner case should have been handled in splice_play().
 137                 }
 138         }
 139
 140         steady_clock::duration time_slept = steady_clock::now() - before_sleep;
 141         pts += duration_cast<duration<size_t, TimebaseRatio>>(time_slept).count();
 142
 143         if (!clip_ready) {
 144                 if (video_stream != nullptr) {
 145                         ++metric_refresh_frame;
 146                         video_stream->schedule_refresh_frame(steady_clock::now(), pts, /*display_func=*/nullptr, QueueSpotHolder());
 147                 }
 148                 return;
 149         }
 150
 151         steady_clock::time_point origin = steady_clock::now();  // TODO: Add a 100 ms buffer for ramp-up?
 152         int64_t in_pts_origin = clip_list[0].clip.pts_in;
 153         for (size_t clip_idx = 0; clip_idx < clip_list.size(); ++clip_idx) {
 154                 const Clip *clip = &clip_list[clip_idx].clip;
 155                 const Clip *next_clip = (clip_idx + 1 < clip_list.size()) ? &clip_list[clip_idx + 1].clip : nullptr;
 156                 int64_t out_pts_origin = pts;
 157
 158                 double next_clip_fade_time = -1.0;
 159                 if (next_clip != nullptr) {
 160                         double duration_this_clip = double(clip->pts_out - in_pts_origin) / TIMEBASE / clip->speed;
 161                         double duration_next_clip = double(next_clip->pts_out - next_clip->pts_in) / TIMEBASE / clip->speed;
 162                         next_clip_fade_time = min(min(duration_this_clip, duration_next_clip), clip->fade_time_seconds);
 163                 }
 164
 165                 int stream_idx = clip->stream_idx;
 166
 167                 // Start playing exactly at a frame.
 168                 // TODO: Snap secondary (fade-to) clips in the same fashion
 169                 // so that we don't get jank here).
 170                 {
 171                         lock_guard<mutex> lock(frame_mu);
 172
 173                         // Find the first frame such that frame.pts <= in_pts.
 174                         auto it = find_last_frame_before(frames[stream_idx], in_pts_origin);
 175                         if (it != frames[stream_idx].end()) {
 176                                 in_pts_origin = it->pts;
 177                         }
 178                 }
 179
 180                 steady_clock::time_point next_frame_start;
 181                 for (int frameno = 0; !should_quit; ++frameno) {  // Ends when the clip ends.
 182                         double out_pts = out_pts_origin + TIMEBASE * frameno / global_flags.output_framerate;
 183                         next_frame_start =
 184                                 origin + microseconds(lrint((out_pts - out_pts_origin) * 1e6 / TIMEBASE));
 185                         int64_t in_pts = lrint(in_pts_origin + TIMEBASE * frameno * clip->speed / global_flags.output_framerate);
 186                         pts = lrint(out_pts);
 187
 188                         if (in_pts >= clip->pts_out) {
 189                                 break;
 190                         }
 191
 192                         {
 193                                 lock_guard<mutex> lock(queue_state_mu);
 194                                 if (splice_ready) {
 195                                         fprintf(stderr, "splicing\n");
 196                                         if (next_clip == nullptr) {
 197                                                 do_splice(to_splice_clip_list, clip_idx, -1, &clip_list);
 198                                         } else {
 199                                                 do_splice(to_splice_clip_list, clip_idx, clip_idx + 1, &clip_list);
 200                                         }
 201                                         to_splice_clip_list.clear();
 202                                         splice_ready = false;
 203
 204                                         // Refresh the clip pointer, since the clip list may have been reallocated.
 205                                         clip = &clip_list[clip_idx].clip;
 206
 207                                         // Recompute next_clip and any needed fade times, since the next clip may have changed
 208                                         // (or we may have gone from no new clip to having one, or the other way).
 209                                         next_clip = (clip_idx + 1 < clip_list.size()) ? &clip_list[clip_idx + 1].clip : nullptr;
 210                                         if (next_clip != nullptr) {
 211                                                 double duration_this_clip = double(clip->pts_out - in_pts) / TIMEBASE / clip->speed;
 212                                                 double duration_next_clip = double(next_clip->pts_out - next_clip->pts_in) / TIMEBASE / clip->speed;
 213                                                 next_clip_fade_time = min(min(duration_this_clip, duration_next_clip), clip->fade_time_seconds);
 214                                         }
 215                                 }
 216                         }
 217
 218                         steady_clock::duration time_behind = steady_clock::now() - next_frame_start;
 219                         if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(200)) {
 220                                 fprintf(stderr, "WARNING: %ld ms behind, dropping a frame (no matter the type).\n",
 221                                         lrint(1e3 * duration<double>(time_behind).count()));
 222                                 ++metric_dropped_unconditional_frame;
 223                                 continue;
 224                         }
 225
 226                         // pts not affected by the swapping below.
 227                         int64_t in_pts_for_progress = in_pts, in_pts_secondary_for_progress = -1;
 228
 229                         int primary_stream_idx = stream_idx;
 230                         FrameOnDisk secondary_frame;
 231                         int secondary_stream_idx = -1;
 232                         float fade_alpha = 0.0f;
 233                         double time_left_this_clip = double(clip->pts_out - in_pts) / TIMEBASE / clip->speed;
 234                         if (next_clip != nullptr && time_left_this_clip <= next_clip_fade_time) {
 235                                 // We're in a fade to the next clip->
 236                                 secondary_stream_idx = next_clip->stream_idx;
 237                                 int64_t in_pts_secondary = lrint(next_clip->pts_in + (next_clip_fade_time - time_left_this_clip) * TIMEBASE * clip->speed);
 238                                 in_pts_secondary_for_progress = in_pts_secondary;
 239                                 fade_alpha = 1.0f - time_left_this_clip / next_clip_fade_time;
 240
 241                                 // If more than half-way through the fade, interpolate the next clip
 242                                 // instead of the current one, since it's more visible.
 243                                 if (fade_alpha >= 0.5f) {
 244                                         swap(primary_stream_idx, secondary_stream_idx);
 245                                         swap(in_pts, in_pts_secondary);
 246                                         fade_alpha = 1.0f - fade_alpha;
 247                                 }
 248
 249                                 FrameOnDisk frame_lower, frame_upper;
 250                                 bool ok = find_surrounding_frames(in_pts_secondary, secondary_stream_idx, &frame_lower, &frame_upper);
 251                                 if (ok) {
 252                                         secondary_frame = frame_lower;
 253                                 }
 254                         }
 255
 256                         if (progress_callback != nullptr) {
 257                                 // NOTE: None of this will take into account any snapping done below.
 258                                 double clip_progress = calc_progress(*clip, in_pts_for_progress);
 259                                 map<uint64_t, double> progress{ { clip_list[clip_idx].id, clip_progress } };
 260                                 double time_remaining;
 261                                 if (next_clip != nullptr && time_left_this_clip <= next_clip_fade_time) {
 262                                         double next_clip_progress = calc_progress(*next_clip, in_pts_secondary_for_progress);
 263                                         progress[clip_list[clip_idx + 1].id] = next_clip_progress;
 264                                         time_remaining = compute_time_left(clip_list, clip_idx + 1, next_clip_progress);
 265                                 } else {
 266                                         time_remaining = compute_time_left(clip_list, clip_idx, clip_progress);
 267                                 }
 268                                 progress_callback(progress, time_remaining);
 269                         }
 270
 271                         FrameOnDisk frame_lower, frame_upper;
 272                         bool ok = find_surrounding_frames(in_pts, primary_stream_idx, &frame_lower, &frame_upper);
 273                         if (!ok) {
 274                                 break;
 275                         }
 276
 277                         // Wait until we should, or (given buffering) can, output the frame.
 278                         {
 279                                 unique_lock<mutex> lock(queue_state_mu);
 280                                 if (video_stream == nullptr) {
 281                                         // No queue, just wait until the right time and then show the frame.
 282                                         new_clip_changed.wait_until(lock, next_frame_start, [this] {
 283                                                 return should_quit || new_clip_ready || override_stream_idx != -1;
 284                                         });
 285                                         if (should_quit) {
 286                                                 return;
 287                                         }
 288                                 } else {
 289                                         // If the queue is full (which is really the state we'd like to be in),
 290                                         // wait until there's room for one more frame (ie., one was output from
 291                                         // VideoStream), or until or until there's a new clip we're supposed to play.
 292                                         //
 293                                         // In this case, we don't sleep until next_frame_start; the displaying is
 294                                         // done by the queue.
 295                                         new_clip_changed.wait(lock, [this] {
 296                                                 if (num_queued_frames < max_queued_frames) {
 297                                                         return true;
 298                                                 }
 299                                                 return should_quit || new_clip_ready || override_stream_idx != -1;
 300                                         });
 301                                 }
 302                                 if (should_quit) {
 303                                         return;
 304                                 }
 305                                 if (new_clip_ready) {
 306                                         if (video_stream != nullptr) {
 307                                                 lock.unlock();  // Urg.
 308                                                 video_stream->clear_queue();
 309                                                 lock.lock();
 310                                         }
 311                                         return;
 312                                 }
 313                                 // Honor if we got an override request for the camera.
 314                                 if (override_stream_idx != -1) {
 315                                         stream_idx = override_stream_idx;
 316                                         override_stream_idx = -1;
 317                                         continue;
 318                                 }
 319                         }
 320
 321                         // If there's nothing to interpolate between, or if interpolation is turned off,
 322                         // or we're a preview, then just display the frame.
 323                         if (frame_lower.pts == frame_upper.pts || global_flags.interpolation_quality == 0 || video_stream == nullptr) {
 324                                 display_single_frame(primary_stream_idx, frame_lower, secondary_stream_idx,
 325                                                      secondary_frame, fade_alpha, next_frame_start, /*snapped=*/false);
 326                                 continue;
 327                         }
 328
 329                         // Snap to input frame: If we can do so with less than 1% jitter
 330                         // (ie., move less than 1% of an _output_ frame), do so.
 331                         // TODO: Snap secondary (fade-to) clips in the same fashion.
 332                         double pts_snap_tolerance = 0.01 * double(TIMEBASE) / global_flags.output_framerate;
 333                         bool snapped = false;
 334                         for (FrameOnDisk snap_frame : { frame_lower, frame_upper }) {
 335                                 if (fabs(snap_frame.pts - in_pts) < pts_snap_tolerance) {
 336                                         display_single_frame(primary_stream_idx, snap_frame, secondary_stream_idx,
 337                                                              secondary_frame, fade_alpha, next_frame_start, /*snapped=*/true);
 338                                         in_pts_origin += snap_frame.pts - in_pts;
 339                                         snapped = true;
 340                                         break;
 341                                 }
 342                         }
 343                         if (snapped) {
 344                                 continue;
 345                         }
 346
 347                         // The snapping above makes us lock to the input framerate, even in the presence
 348                         // of pts drift, for most typical cases where it's needed, like converting 60 → 2x60
 349                         // or 60 → 2x59.94. However, there are some corner cases like 25 → 2x59.94, where we'd
 350                         // get a snap very rarely (in the given case, once every 24 output frames), and by
 351                         // that time, we'd have drifted out. We could have solved this by changing the overall
 352                         // speed ever so slightly, but it requires that we know the actual frame rate (which
 353                         // is difficult in the presence of jitter and missed frames), or at least do some kind
 354                         // of matching/clustering. Instead, we take the opportunity to lock to in-between rational
 355                         // points if we can. E.g., if we are converting 60 → 2x60, we would not only snap to
 356                         // an original frame every other frame; we would also snap to exactly alpha=0.5 every
 357                         // in-between frame. Of course, we will still need to interpolate, but we get a lot
 358                         // closer when we actually get close to an original frame. In other words: Snap more
 359                         // often, but snap less each time. Unless the input and output frame rates are completely
 360                         // decorrelated with no common factor, of course (e.g. 12.345 → 34.567, which we should
 361                         // really never see in practice).
 362                         for (double fraction : { 1.0 / 2.0, 1.0 / 3.0, 2.0 / 3.0, 1.0 / 4.0, 3.0 / 4.0,
 363                                                  1.0 / 5.0, 2.0 / 5.0, 3.0 / 5.0, 4.0 / 5.0 }) {
 364                                 double subsnap_pts = frame_lower.pts + fraction * (frame_upper.pts - frame_lower.pts);
 365                                 if (fabs(subsnap_pts - in_pts) < pts_snap_tolerance) {
 366                                         in_pts_origin += lrint(subsnap_pts) - in_pts;
 367                                         in_pts = lrint(subsnap_pts);
 368                                         break;
 369                                 }
 370                         }
 371
 372                         if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(100)) {
 373                                 fprintf(stderr, "WARNING: %ld ms behind, dropping an interpolated frame.\n",
 374                                         lrint(1e3 * duration<double>(time_behind).count()));
 375                                 ++metric_dropped_interpolated_frame;
 376                                 continue;
 377                         }
 378
 379                         double alpha = double(in_pts - frame_lower.pts) / (frame_upper.pts - frame_lower.pts);
 380                         auto display_func = [this](shared_ptr<Frame> frame) {
 381                                 if (destination != nullptr) {
 382                                         destination->setFrame(frame);
 383                                 }
 384                         };
 385                         if (secondary_stream_idx == -1) {
 386                                 ++metric_interpolated_frame;
 387                         } else {
 388                                 ++metric_interpolated_faded_frame;
 389                         }
 390                         video_stream->schedule_interpolated_frame(
 391                                 next_frame_start, pts, display_func, QueueSpotHolder(this),
 392                                 frame_lower, frame_upper, alpha,
 393                                 secondary_frame, fade_alpha);
 394                         last_pts_played = in_pts;  // Not really needed; only previews use last_pts_played.
 395                 }
 396
 397                 // The clip ended.
 398                 if (should_quit) {
 399                         return;
 400                 }
 401
 402                 // Start the next clip from the point where the fade went out.
 403                 if (next_clip != nullptr) {
 404                         origin = next_frame_start;
 405                         in_pts_origin = next_clip->pts_in + lrint(next_clip_fade_time * TIMEBASE * clip->speed);
 406                 }
 407         }
 408 }
 409
 410 void Player::display_single_frame(int primary_stream_idx, const FrameOnDisk &primary_frame, int secondary_stream_idx, const FrameOnDisk &secondary_frame, double fade_alpha, steady_clock::time_point frame_start, bool snapped)
 411 {
 412         auto display_func = [this, primary_stream_idx, primary_frame, secondary_frame, fade_alpha] {
 413                 if (destination != nullptr) {
 414                         destination->setFrame(primary_stream_idx, primary_frame, secondary_frame, fade_alpha);
 415                 }
 416         };
 417         if (video_stream == nullptr) {
 418                 display_func();
 419         } else {
 420                 if (secondary_stream_idx == -1) {
 421                         // NOTE: We could be increasing unused metrics for previews, but that's harmless.
 422                         if (snapped) {
 423                                 ++metric_original_snapped_frame;
 424                         } else {
 425                                 ++metric_original_frame;
 426                         }
 427                         video_stream->schedule_original_frame(
 428                                 frame_start, pts, display_func, QueueSpotHolder(this),
 429                                 primary_frame);
 430                 } else {
 431                         assert(secondary_frame.pts != -1);
 432                         // NOTE: We could be increasing unused metrics for previews, but that's harmless.
 433                         if (snapped) {
 434                                 ++metric_faded_snapped_frame;
 435                         } else {
 436                                 ++metric_faded_frame;
 437                         }
 438                         video_stream->schedule_faded_frame(frame_start, pts, display_func,
 439                                                            QueueSpotHolder(this), primary_frame,
 440                                                            secondary_frame, fade_alpha);
 441                 }
 442         }
 443         last_pts_played = primary_frame.pts;
 444 }
 445
 446 // Find the frame immediately before and after this point.
 447 bool Player::find_surrounding_frames(int64_t pts, int stream_idx, FrameOnDisk *frame_lower, FrameOnDisk *frame_upper)
 448 {
 449         lock_guard<mutex> lock(frame_mu);
 450
 451         // Find the first frame such that frame.pts >= pts.
 452         auto it = find_last_frame_before(frames[stream_idx], pts);
 453         if (it == frames[stream_idx].end()) {
 454                 return false;
 455         }
 456         *frame_upper = *it;
 457
 458         // Find the last frame such that in_pts <= frame.pts (if any).
 459         if (it == frames[stream_idx].begin()) {
 460                 *frame_lower = *it;
 461         } else {
 462                 *frame_lower = *(it - 1);
 463         }
 464         assert(pts >= frame_lower->pts);
 465         assert(pts <= frame_upper->pts);
 466         return true;
 467 }
 468
 469 Player::Player(JPEGFrameView *destination, Player::StreamOutput stream_output, AVFormatContext *file_avctx)
 470         : destination(destination), stream_output(stream_output)
 471 {
 472         player_thread = thread(&Player::thread_func, this, file_avctx);
 473
 474         if (stream_output == HTTPD_STREAM_OUTPUT) {
 475                 global_metrics.add("http_output_frames", { { "type", "original" }, { "reason", "edge_frame_or_no_interpolation" } }, &metric_original_frame);
 476                 global_metrics.add("http_output_frames", { { "type", "faded" }, { "reason", "edge_frame_or_no_interpolation" } }, &metric_faded_frame);
 477                 global_metrics.add("http_output_frames", { { "type", "original" }, { "reason", "snapped" } }, &metric_original_snapped_frame);
 478                 global_metrics.add("http_output_frames", { { "type", "faded" }, { "reason", "snapped" } }, &metric_faded_snapped_frame);
 479                 global_metrics.add("http_output_frames", { { "type", "interpolated" } }, &metric_interpolated_frame);
 480                 global_metrics.add("http_output_frames", { { "type", "interpolated_faded" } }, &metric_interpolated_faded_frame);
 481                 global_metrics.add("http_output_frames", { { "type", "refresh" } }, &metric_refresh_frame);
 482                 global_metrics.add("http_dropped_frames", { { "type", "interpolated" } }, &metric_dropped_interpolated_frame);
 483                 global_metrics.add("http_dropped_frames", { { "type", "unconditional" } }, &metric_dropped_unconditional_frame);
 484         }
 485 }
 486
 487 Player::~Player()
 488 {
 489         should_quit = true;
 490         if (video_stream != nullptr) {
 491                 video_stream->stop();
 492         }
 493         new_clip_changed.notify_all();
 494         player_thread.join();
 495 }
 496
 497 void Player::play(const vector<ClipWithID> &clips)
 498 {
 499         lock_guard<mutex> lock(queue_state_mu);
 500         new_clip_ready = true;
 501         queued_clip_list = clips;
 502         splice_ready = false;
 503         override_stream_idx = -1;
 504         new_clip_changed.notify_all();
 505 }
 506
 507 void Player::splice_play(const vector<ClipWithID> &clips)
 508 {
 509         lock_guard<mutex> lock(queue_state_mu);
 510         if (new_clip_ready) {
 511                 queued_clip_list = clips;
 512                 assert(!splice_ready);
 513                 return;
 514         }
 515
 516         splice_ready = true;
 517         to_splice_clip_list = clips;  // Overwrite any queued but not executed splice.
 518 }
 519
 520 void Player::override_angle(unsigned stream_idx)
 521 {
 522         int64_t last_pts;
 523
 524         // Corner case: If a new clip is waiting to be played, change its stream and then we're done.
 525         {
 526                 lock_guard<mutex> lock(queue_state_mu);
 527                 if (new_clip_ready) {
 528                         assert(queued_clip_list.size() == 1);
 529                         queued_clip_list[0].clip.stream_idx = stream_idx;
 530                         return;
 531                 }
 532
 533                 // If we are playing a clip, set override_stream_idx, and the player thread will
 534                 // pick it up and change its internal index.
 535                 if (playing) {
 536                         override_stream_idx = stream_idx;
 537                         new_clip_changed.notify_all();
 538                         return;
 539                 }
 540
 541                 // OK, so we're standing still, presumably at the end of a clip.
 542                 // Look at the last frame played (if it exists), and show the closest
 543                 // thing we've got.
 544                 if (last_pts_played < 0) {
 545                         return;
 546                 }
 547                 last_pts = last_pts_played;
 548         }
 549
 550         lock_guard<mutex> lock(frame_mu);
 551         auto it = find_first_frame_at_or_after(frames[stream_idx], last_pts);
 552         if (it == frames[stream_idx].end()) {
 553                 return;
 554         }
 555         destination->setFrame(stream_idx, *it);
 556 }
 557
 558 void Player::take_queue_spot()
 559 {
 560         lock_guard<mutex> lock(queue_state_mu);
 561         ++num_queued_frames;
 562 }
 563
 564 void Player::release_queue_spot()
 565 {
 566         lock_guard<mutex> lock(queue_state_mu);
 567         assert(num_queued_frames > 0);
 568         --num_queued_frames;
 569         new_clip_changed.notify_all();
 570 }
 571
 572 double compute_time_left(const vector<ClipWithID> &clips, size_t currently_playing_idx, double progress_currently_playing)
 573 {
 574         // Look at the last clip and then start counting from there.
 575         double remaining = 0.0;
 576         double last_fade_time_seconds = 0.0;
 577         for (size_t row = currently_playing_idx; row < clips.size(); ++row) {
 578                 const Clip &clip = clips[row].clip;
 579                 double clip_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / clip.speed;
 580                 if (row == currently_playing_idx) {
 581                         // A clip we're playing: Subtract the part we've already played.
 582                         remaining = clip_length * (1.0 - progress_currently_playing);
 583                 } else {
 584                         // A clip we haven't played yet: Subtract the part that's overlapping
 585                         // with a previous clip (due to fade).
 586                         remaining += max(clip_length - last_fade_time_seconds, 0.0);
 587                 }
 588                 last_fade_time_seconds = min(clip_length, clip.fade_time_seconds);
 589         }
 590         return remaining;
 591 }