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

   1 #include "jpeg_frame_view.h"
   2
   3 #include "defs.h"
   4 #include "flags.h"
   5 #include "jpeg_destroyer.h"
   6 #include "jpeglib_error_wrapper.h"
   7 #include "shared/metrics.h"
   8 #include "shared/post_to_main_thread.h"
   9 #include "video_stream.h"
  10 #include "ycbcr_converter.h"
  11
  12 #include <QMouseEvent>
  13 #include <QScreen>
  14 #include <atomic>
  15 #include <chrono>
  16 #include <condition_variable>
  17 #include <deque>
  18 #include <jpeglib.h>
  19 #include <movit/init.h>
  20 #include <movit/resource_pool.h>
  21 #include <movit/util.h>
  22 #include <mutex>
  23 #include <stdint.h>
  24 #include <thread>
  25 #include <unistd.h>
  26 #include <utility>
  27
  28 // Must come after the Qt stuff.
  29 #include "vaapi_jpeg_decoder.h"
  30
  31 using namespace movit;
  32 using namespace std;
  33 using namespace std::chrono;
  34
  35 namespace {
  36
  37 // Just an arbitrary order for std::map.
  38 struct FrameOnDiskLexicalOrder {
  39         bool operator()(const FrameOnDisk &a, const FrameOnDisk &b) const
  40         {
  41                 if (a.pts != b.pts)
  42                         return a.pts < b.pts;
  43                 if (a.offset != b.offset)
  44                         return a.offset < b.offset;
  45                 if (a.filename_idx != b.filename_idx)
  46                         return a.filename_idx < b.filename_idx;
  47                 assert(a.size == b.size);
  48                 return false;
  49         }
  50 };
  51
  52 inline size_t frame_size(const Frame &frame)
  53 {
  54         size_t y_size = frame.width * frame.height;
  55         size_t cbcr_size = y_size / frame.chroma_subsampling_x / frame.chroma_subsampling_y;
  56         return y_size + cbcr_size * 2;
  57 }
  58
  59 struct LRUFrame {
  60         shared_ptr<Frame> frame;
  61         size_t last_used;
  62 };
  63
  64 // There can be multiple JPEGFrameView instances, so make all the metrics static.
  65 once_flag jpeg_metrics_inited;
  66 atomic<int64_t> metric_jpeg_cache_used_bytes{ 0 };  // Same value as cache_bytes_used.
  67 atomic<int64_t> metric_jpeg_cache_limit_bytes{ size_t(CACHE_SIZE_MB) * 1024 * 1024 };
  68 atomic<int64_t> metric_jpeg_cache_given_up_frames{ 0 };
  69 atomic<int64_t> metric_jpeg_cache_hit_frames{ 0 };
  70 atomic<int64_t> metric_jpeg_cache_miss_frames{ 0 };
  71 atomic<int64_t> metric_jpeg_software_decode_frames{ 0 };
  72 atomic<int64_t> metric_jpeg_software_fail_frames{ 0 };
  73 atomic<int64_t> metric_jpeg_vaapi_decode_frames{ 0 };
  74 atomic<int64_t> metric_jpeg_vaapi_fail_frames{ 0 };
  75 Summary metric_jpeg_decode_time_seconds;
  76
  77 }  // namespace
  78
  79 mutex cache_mu;
  80 map<FrameOnDisk, LRUFrame, FrameOnDiskLexicalOrder> cache;  // Under cache_mu.
  81 size_t cache_bytes_used = 0;  // Under cache_mu.
  82 atomic<size_t> event_counter{ 0 };
  83 extern QGLWidget *global_share_widget;
  84 extern atomic<bool> should_quit;
  85
  86 shared_ptr<Frame> decode_jpeg(const string &jpeg)
  87 {
  88         steady_clock::time_point start = steady_clock::now();
  89         shared_ptr<Frame> frame;
  90         if (vaapi_jpeg_decoding_usable) {
  91                 frame = decode_jpeg_vaapi(jpeg);
  92                 if (frame != nullptr) {
  93                         ++metric_jpeg_vaapi_decode_frames;
  94                         steady_clock::time_point stop = steady_clock::now();
  95                         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
  96                         return frame;
  97                 }
  98                 fprintf(stderr, "VA-API hardware decoding failed; falling back to software.\n");
  99                 ++metric_jpeg_vaapi_fail_frames;
 100         }
 101
 102         frame.reset(new Frame);
 103
 104         jpeg_decompress_struct dinfo;
 105         JPEGWrapErrorManager error_mgr(&dinfo);
 106         if (!error_mgr.run([&dinfo] { jpeg_create_decompress(&dinfo); })) {
 107                 return get_black_frame();
 108         }
 109         JPEGDestroyer destroy_dinfo(&dinfo);
 110
 111         if (!error_mgr.run([&dinfo, &jpeg] {
 112                     jpeg_mem_src(&dinfo, reinterpret_cast<const unsigned char *>(jpeg.data()), jpeg.size());
 113                     jpeg_read_header(&dinfo, true);
 114             })) {
 115                 return get_black_frame();
 116         }
 117
 118         jpeg_save_markers(&dinfo, JPEG_APP0 + 1, 0xFFFF);
 119
 120         if (dinfo.num_components != 3) {
 121                 fprintf(stderr, "Not a color JPEG. (%d components, Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
 122                         dinfo.num_components,
 123                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
 124                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
 125                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
 126                 return get_black_frame();
 127         }
 128         if (dinfo.comp_info[0].h_samp_factor != dinfo.max_h_samp_factor ||
 129             dinfo.comp_info[0].v_samp_factor != dinfo.max_v_samp_factor ||  // Y' must not be subsampled.
 130             dinfo.comp_info[1].h_samp_factor != dinfo.comp_info[2].h_samp_factor ||
 131             dinfo.comp_info[1].v_samp_factor != dinfo.comp_info[2].v_samp_factor ||  // Cb and Cr must be identically subsampled.
 132             (dinfo.max_h_samp_factor % dinfo.comp_info[1].h_samp_factor) != 0 ||
 133             (dinfo.max_v_samp_factor % dinfo.comp_info[1].v_samp_factor) != 0) {  // No 2:3 subsampling or other weirdness.
 134                 fprintf(stderr, "Unsupported subsampling scheme. (Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
 135                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
 136                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
 137                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
 138                 abort();
 139         }
 140         dinfo.raw_data_out = true;
 141
 142         if (!error_mgr.run([&dinfo] {
 143                     jpeg_start_decompress(&dinfo);
 144             })) {
 145                 return get_black_frame();
 146         }
 147
 148         frame->width = dinfo.output_width;
 149         frame->height = dinfo.output_height;
 150         frame->chroma_subsampling_x = dinfo.max_h_samp_factor / dinfo.comp_info[1].h_samp_factor;
 151         frame->chroma_subsampling_y = dinfo.max_v_samp_factor / dinfo.comp_info[1].v_samp_factor;
 152
 153         unsigned h_mcu_size = DCTSIZE * dinfo.max_h_samp_factor;
 154         unsigned v_mcu_size = DCTSIZE * dinfo.max_v_samp_factor;
 155         unsigned mcu_width_blocks = (dinfo.output_width + h_mcu_size - 1) / h_mcu_size;
 156         unsigned mcu_height_blocks = (dinfo.output_height + v_mcu_size - 1) / v_mcu_size;
 157
 158         unsigned luma_width_blocks = mcu_width_blocks * dinfo.comp_info[0].h_samp_factor;
 159         unsigned chroma_width_blocks = mcu_width_blocks * dinfo.comp_info[1].h_samp_factor;
 160         unsigned luma_height_blocks = mcu_height_blocks * dinfo.comp_info[0].v_samp_factor;
 161         unsigned chroma_height_blocks = mcu_height_blocks * dinfo.comp_info[1].v_samp_factor;
 162
 163         // TODO: Decode into a PBO.
 164         frame->y.reset(new uint8_t[luma_width_blocks * luma_height_blocks * DCTSIZE2]);
 165         frame->cb.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
 166         frame->cr.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
 167         frame->pitch_y = luma_width_blocks * DCTSIZE;
 168         frame->pitch_chroma = chroma_width_blocks * DCTSIZE;
 169
 170         if (dinfo.marker_list != nullptr &&
 171             dinfo.marker_list->marker == JPEG_APP0 + 1 &&
 172             dinfo.marker_list->data_length >= 4 &&
 173             memcmp(dinfo.marker_list->data, "Exif", 4) == 0) {
 174                 frame->exif_data.assign(reinterpret_cast<char *>(dinfo.marker_list->data),
 175                         dinfo.marker_list->data_length);
 176         }
 177
 178         if (!error_mgr.run([&dinfo, &frame, v_mcu_size, mcu_height_blocks] {
 179                     JSAMPROW yptr[v_mcu_size], cbptr[v_mcu_size], crptr[v_mcu_size];
 180                     JSAMPARRAY data[3] = { yptr, cbptr, crptr };
 181                     for (unsigned y = 0; y < mcu_height_blocks; ++y) {
 182                             // NOTE: The last elements of cbptr/crptr will be unused for vertically subsampled chroma.
 183                             for (unsigned yy = 0; yy < v_mcu_size; ++yy) {
 184                                     yptr[yy] = frame->y.get() + (y * DCTSIZE * dinfo.max_v_samp_factor + yy) * frame->pitch_y;
 185                                     cbptr[yy] = frame->cb.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * frame->pitch_chroma;
 186                                     crptr[yy] = frame->cr.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * frame->pitch_chroma;
 187                             }
 188
 189                             jpeg_read_raw_data(&dinfo, data, v_mcu_size);
 190                     }
 191
 192                     (void)jpeg_finish_decompress(&dinfo);
 193             })) {
 194                 return get_black_frame();
 195         }
 196
 197         ++metric_jpeg_software_decode_frames;
 198         steady_clock::time_point stop = steady_clock::now();
 199         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
 200         return frame;
 201 }
 202
 203 void prune_cache()
 204 {
 205         // Assumes cache_mu is held.
 206         int64_t bytes_still_to_remove = cache_bytes_used - (size_t(CACHE_SIZE_MB) * 1024 * 1024) * 9 / 10;
 207         if (bytes_still_to_remove <= 0)
 208                 return;
 209
 210         vector<pair<size_t, size_t>> lru_timestamps_and_size;
 211         for (const auto &key_and_value : cache) {
 212                 lru_timestamps_and_size.emplace_back(
 213                         key_and_value.second.last_used,
 214                         frame_size(*key_and_value.second.frame));
 215         }
 216         sort(lru_timestamps_and_size.begin(), lru_timestamps_and_size.end());
 217
 218         // Remove the oldest ones until we are below 90% of the cache used.
 219         size_t lru_cutoff_point = 0;
 220         for (const pair<size_t, size_t> &it : lru_timestamps_and_size) {
 221                 lru_cutoff_point = it.first;
 222                 bytes_still_to_remove -= it.second;
 223                 if (bytes_still_to_remove <= 0)
 224                         break;
 225         }
 226
 227         for (auto it = cache.begin(); it != cache.end();) {
 228                 if (it->second.last_used <= lru_cutoff_point) {
 229                         cache_bytes_used -= frame_size(*it->second.frame);
 230                         metric_jpeg_cache_used_bytes = cache_bytes_used;
 231                         it = cache.erase(it);
 232                 } else {
 233                         ++it;
 234                 }
 235         }
 236 }
 237
 238 shared_ptr<Frame> decode_jpeg_with_cache(FrameOnDisk frame_spec, CacheMissBehavior cache_miss_behavior, FrameReader *frame_reader, bool *did_decode)
 239 {
 240         *did_decode = false;
 241         {
 242                 lock_guard<mutex> lock(cache_mu);
 243                 auto it = cache.find(frame_spec);
 244                 if (it != cache.end()) {
 245                         ++metric_jpeg_cache_hit_frames;
 246                         it->second.last_used = event_counter++;
 247                         return it->second.frame;
 248                 }
 249         }
 250
 251         if (cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE) {
 252                 ++metric_jpeg_cache_given_up_frames;
 253                 return nullptr;
 254         }
 255
 256         ++metric_jpeg_cache_miss_frames;
 257
 258         *did_decode = true;
 259         shared_ptr<Frame> frame = decode_jpeg(frame_reader->read_frame(frame_spec, /*read_video=*/true, /*read_audio=*/false).video);
 260
 261         lock_guard<mutex> lock(cache_mu);
 262         cache_bytes_used += frame_size(*frame);
 263         metric_jpeg_cache_used_bytes = cache_bytes_used;
 264         cache[frame_spec] = LRUFrame{ frame, event_counter++ };
 265
 266         if (cache_bytes_used > size_t(CACHE_SIZE_MB) * 1024 * 1024) {
 267                 prune_cache();
 268         }
 269         return frame;
 270 }
 271
 272 void JPEGFrameView::jpeg_decoder_thread_func()
 273 {
 274         size_t num_decoded = 0, num_dropped = 0;
 275
 276         pthread_setname_np(pthread_self(), "JPEGDecoder");
 277         while (!should_quit.load()) {
 278                 PendingDecode decode;
 279                 CacheMissBehavior cache_miss_behavior = DECODE_IF_NOT_IN_CACHE;
 280                 {
 281                         unique_lock<mutex> lock(cache_mu);  // TODO: Perhaps under another lock?
 282                         any_pending_decodes.wait(lock, [this] {
 283                                 return !pending_decodes.empty() || should_quit.load();
 284                         });
 285                         if (should_quit.load())
 286                                 break;
 287                         decode = pending_decodes.front();
 288                         pending_decodes.pop_front();
 289
 290                         if (pending_decodes.size() > 3) {
 291                                 cache_miss_behavior = RETURN_NULLPTR_IF_NOT_IN_CACHE;
 292                         }
 293                 }
 294
 295                 if (decode.frame != nullptr) {
 296                         // Already decoded, so just show it.
 297                         setDecodedFrame(decode.frame, nullptr, 1.0f);
 298                         continue;
 299                 }
 300
 301                 shared_ptr<Frame> primary_frame, secondary_frame;
 302                 bool drop = false;
 303                 for (int subframe_idx = 0; subframe_idx < 2; ++subframe_idx) {
 304                         const FrameOnDisk &frame_spec = (subframe_idx == 0 ? decode.primary : decode.secondary);
 305                         if (frame_spec.pts == -1) {
 306                                 // No secondary frame.
 307                                 continue;
 308                         }
 309
 310                         bool found_in_cache;
 311                         shared_ptr<Frame> frame = decode_jpeg_with_cache(frame_spec, cache_miss_behavior, &frame_reader, &found_in_cache);
 312
 313                         if (frame == nullptr) {
 314                                 assert(cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE);
 315                                 drop = true;
 316                                 break;
 317                         }
 318
 319                         if (!found_in_cache) {
 320                                 ++num_decoded;
 321                                 if (num_decoded % 1000 == 0) {
 322                                         fprintf(stderr, "Decoded %zu images, dropped %zu (%.2f%% dropped)\n",
 323                                                 num_decoded, num_dropped, (100.0 * num_dropped) / (num_decoded + num_dropped));
 324                                 }
 325                         }
 326                         if (subframe_idx == 0) {
 327                                 primary_frame = std::move(frame);
 328                         } else {
 329                                 secondary_frame = std::move(frame);
 330                         }
 331                 }
 332                 if (drop) {
 333                         ++num_dropped;
 334                         continue;
 335                 }
 336
 337                 // TODO: Could we get jitter between non-interpolated and interpolated frames here?
 338                 setDecodedFrame(primary_frame, secondary_frame, decode.fade_alpha);
 339         }
 340 }
 341
 342 JPEGFrameView::~JPEGFrameView()
 343 {
 344         any_pending_decodes.notify_all();
 345         jpeg_decoder_thread.join();
 346 }
 347
 348 JPEGFrameView::JPEGFrameView(QWidget *parent)
 349         : QGLWidget(parent, global_share_widget)
 350 {
 351         call_once(jpeg_metrics_inited, [] {
 352                 global_metrics.add("jpeg_cache_used_bytes", &metric_jpeg_cache_used_bytes, Metrics::TYPE_GAUGE);
 353                 global_metrics.add("jpeg_cache_limit_bytes", &metric_jpeg_cache_limit_bytes, Metrics::TYPE_GAUGE);
 354                 global_metrics.add("jpeg_cache_frames", { { "action", "given_up" } }, &metric_jpeg_cache_given_up_frames);
 355                 global_metrics.add("jpeg_cache_frames", { { "action", "hit" } }, &metric_jpeg_cache_hit_frames);
 356                 global_metrics.add("jpeg_cache_frames", { { "action", "miss" } }, &metric_jpeg_cache_miss_frames);
 357                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "decode" } }, &metric_jpeg_software_decode_frames);
 358                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "fail" } }, &metric_jpeg_software_fail_frames);
 359                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "decode" } }, &metric_jpeg_vaapi_decode_frames);
 360                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "fail" } }, &metric_jpeg_vaapi_fail_frames);
 361                 vector<double> quantiles{ 0.01, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99 };
 362                 metric_jpeg_decode_time_seconds.init(quantiles, 60.0);
 363                 global_metrics.add("jpeg_decode_time_seconds", &metric_jpeg_decode_time_seconds);
 364         });
 365 }
 366
 367 void JPEGFrameView::setFrame(unsigned stream_idx, FrameOnDisk frame, FrameOnDisk secondary_frame, float fade_alpha)
 368 {
 369         current_stream_idx = stream_idx;  // TODO: Does this interact with fades?
 370
 371         lock_guard<mutex> lock(cache_mu);
 372         PendingDecode decode;
 373         decode.primary = frame;
 374         decode.secondary = secondary_frame;
 375         decode.fade_alpha = fade_alpha;
 376         pending_decodes.push_back(decode);
 377         any_pending_decodes.notify_all();
 378 }
 379
 380 void JPEGFrameView::setFrame(shared_ptr<Frame> frame)
 381 {
 382         lock_guard<mutex> lock(cache_mu);
 383         PendingDecode decode;
 384         decode.frame = std::move(frame);
 385         pending_decodes.push_back(decode);
 386         any_pending_decodes.notify_all();
 387 }
 388
 389 void JPEGFrameView::initializeGL()
 390 {
 391         glDisable(GL_BLEND);
 392         glDisable(GL_DEPTH_TEST);
 393         check_error();
 394
 395         resource_pool = new ResourcePool;
 396         jpeg_decoder_thread = std::thread(&JPEGFrameView::jpeg_decoder_thread_func, this);
 397
 398         ycbcr_converter.reset(new YCbCrConverter(YCbCrConverter::OUTPUT_TO_RGBA, resource_pool));
 399
 400         ImageFormat inout_format;
 401         inout_format.color_space = COLORSPACE_sRGB;
 402         inout_format.gamma_curve = GAMMA_sRGB;
 403
 404         overlay_chain.reset(new EffectChain(overlay_base_width, overlay_base_height, resource_pool));
 405         overlay_input = (movit::FlatInput *)overlay_chain->add_input(new FlatInput(inout_format, FORMAT_GRAYSCALE, GL_UNSIGNED_BYTE, overlay_base_width, overlay_base_height));
 406
 407         overlay_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
 408         overlay_chain->finalize();
 409 }
 410
 411 void JPEGFrameView::resizeGL(int width, int height)
 412 {
 413         check_error();
 414         glViewport(0, 0, width, height);
 415         check_error();
 416
 417         // Save these, as width() and height() will lie with DPI scaling.
 418         gl_width = width;
 419         gl_height = height;
 420 }
 421
 422 void JPEGFrameView::paintGL()
 423 {
 424         glViewport(0, 0, gl_width, gl_height);
 425         if (current_frame == nullptr) {
 426                 glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
 427                 glClear(GL_COLOR_BUFFER_BIT);
 428                 return;
 429         }
 430
 431         check_error();
 432         current_chain->render_to_screen();
 433
 434         if (overlay_image != nullptr) {
 435                 if (overlay_input_needs_refresh) {
 436                         overlay_input->set_width(overlay_width);
 437                         overlay_input->set_height(overlay_height);
 438                         overlay_input->set_pixel_data(overlay_image->bits());
 439                         overlay_input_needs_refresh = false;
 440                 }
 441                 glViewport(gl_width - overlay_width, 0, overlay_width, overlay_height);
 442                 overlay_chain->render_to_screen();
 443         }
 444 }
 445
 446 namespace {
 447
 448 }  // namespace
 449
 450 void JPEGFrameView::setDecodedFrame(shared_ptr<Frame> frame, shared_ptr<Frame> secondary_frame, float fade_alpha)
 451 {
 452         post_to_main_thread([this, frame, secondary_frame, fade_alpha] {
 453                 current_frame = frame;
 454                 current_secondary_frame = secondary_frame;
 455
 456                 if (secondary_frame != nullptr) {
 457                         current_chain = ycbcr_converter->prepare_chain_for_fade(frame, secondary_frame, fade_alpha);
 458                 } else {
 459                         current_chain = ycbcr_converter->prepare_chain_for_conversion(frame);
 460                 }
 461                 update();
 462         });
 463 }
 464
 465 void JPEGFrameView::mousePressEvent(QMouseEvent *event)
 466 {
 467         if (event->type() == QEvent::MouseButtonPress && event->button() == Qt::LeftButton) {
 468                 emit clicked();
 469         }
 470 }
 471
 472 void JPEGFrameView::set_overlay(const string &text)
 473 {
 474         if (text.empty()) {
 475                 overlay_image.reset();
 476                 return;
 477         }
 478
 479         // Figure out how large the texture needs to be.
 480         {
 481                 QImage img(overlay_width, overlay_height, QImage::Format_Grayscale8);
 482                 QPainter painter(&img);
 483                 QFont font = painter.font();
 484                 font.setPointSize(12);
 485                 QFontMetrics metrics(font);
 486                 overlay_base_width = lrint(metrics.boundingRect(QString::fromStdString(text)).width() + 8.0);
 487                 overlay_base_height = lrint(metrics.height());
 488         }
 489
 490         float dpr = QGuiApplication::primaryScreen()->devicePixelRatio();
 491         overlay_width = lrint(overlay_base_width * dpr);
 492         overlay_height = lrint(overlay_base_height * dpr);
 493
 494         // Work around OpenGL alignment issues.
 495         while (overlay_width % 4 != 0) ++overlay_width;
 496
 497         // Now do the actual drawing.
 498         overlay_image.reset(new QImage(overlay_width, overlay_height, QImage::Format_Grayscale8));
 499         overlay_image->setDevicePixelRatio(dpr);
 500         overlay_image->fill(0);
 501         QPainter painter(overlay_image.get());
 502
 503         painter.setPen(Qt::white);
 504         QFont font = painter.font();
 505         font.setPointSize(12);
 506         painter.setFont(font);
 507
 508         painter.drawText(QRectF(0, 0, overlay_base_width, overlay_base_height), Qt::AlignCenter, QString::fromStdString(text));
 509
 510         // Don't refresh immediately; we might not have an OpenGL context here.
 511         overlay_input_needs_refresh = true;
 512 }
 513
 514 shared_ptr<Frame> get_black_frame()
 515 {
 516         static shared_ptr<Frame> black_frame;
 517         static once_flag flag;
 518         call_once(flag, [] {
 519                 black_frame.reset(new Frame);
 520                 black_frame->y.reset(new uint8_t[global_flags.width * global_flags.height]);
 521                 black_frame->cb.reset(new uint8_t[(global_flags.width / 2) * (global_flags.height / 2)]);
 522                 black_frame->cr.reset(new uint8_t[(global_flags.width / 2) * (global_flags.height / 2)]);
 523                 black_frame->width = global_flags.width;
 524                 black_frame->height = global_flags.height;
 525                 black_frame->chroma_subsampling_x = 2;
 526                 black_frame->chroma_subsampling_y = 2;
 527                 black_frame->pitch_y = global_flags.width;
 528                 black_frame->pitch_chroma = global_flags.width / 2;
 529         });
 530         ++metric_jpeg_software_fail_frames;
 531         return black_frame;
 532 }