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 atomic<int64_t> metric_jpeg_prepared_frames{ 0 };
  76 atomic<int64_t> metric_jpeg_displayed_frames{ 0 };
  77 Summary metric_jpeg_decode_time_seconds;
  78
  79 }  // namespace
  80
  81 mutex cache_mu;
  82 map<FrameOnDisk, LRUFrame, FrameOnDiskLexicalOrder> cache;  // Under cache_mu.
  83 size_t cache_bytes_used = 0;  // Under cache_mu.
  84 atomic<size_t> event_counter{ 0 };
  85 extern QGLWidget *global_share_widget;
  86 extern atomic<bool> should_quit;
  87
  88 shared_ptr<Frame> decode_jpeg(const string &jpeg)
  89 {
  90         steady_clock::time_point start = steady_clock::now();
  91         shared_ptr<Frame> frame;
  92         if (vaapi_jpeg_decoding_usable) {
  93                 frame = decode_jpeg_vaapi(jpeg);
  94                 if (frame != nullptr) {
  95                         ++metric_jpeg_vaapi_decode_frames;
  96                         steady_clock::time_point stop = steady_clock::now();
  97                         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
  98                         return frame;
  99                 }
 100                 fprintf(stderr, "VA-API hardware decoding failed; falling back to software.\n");
 101                 ++metric_jpeg_vaapi_fail_frames;
 102         }
 103
 104         frame.reset(new Frame);
 105
 106         jpeg_decompress_struct dinfo;
 107         JPEGWrapErrorManager error_mgr(&dinfo);
 108         if (!error_mgr.run([&dinfo] { jpeg_create_decompress(&dinfo); })) {
 109                 return get_black_frame();
 110         }
 111         JPEGDestroyer destroy_dinfo(&dinfo);
 112
 113         if (!error_mgr.run([&dinfo, &jpeg] {
 114                     jpeg_mem_src(&dinfo, reinterpret_cast<const unsigned char *>(jpeg.data()), jpeg.size());
 115                     jpeg_read_header(&dinfo, true);
 116             })) {
 117                 return get_black_frame();
 118         }
 119
 120         jpeg_save_markers(&dinfo, JPEG_APP0 + 1, 0xFFFF);
 121
 122         if (dinfo.num_components != 3) {
 123                 fprintf(stderr, "Not a color JPEG. (%d components, Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
 124                         dinfo.num_components,
 125                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
 126                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
 127                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
 128                 return get_black_frame();
 129         }
 130         if (dinfo.comp_info[0].h_samp_factor != dinfo.max_h_samp_factor ||
 131             dinfo.comp_info[0].v_samp_factor != dinfo.max_v_samp_factor ||  // Y' must not be subsampled.
 132             dinfo.comp_info[1].h_samp_factor != dinfo.comp_info[2].h_samp_factor ||
 133             dinfo.comp_info[1].v_samp_factor != dinfo.comp_info[2].v_samp_factor ||  // Cb and Cr must be identically subsampled.
 134             (dinfo.max_h_samp_factor % dinfo.comp_info[1].h_samp_factor) != 0 ||
 135             (dinfo.max_v_samp_factor % dinfo.comp_info[1].v_samp_factor) != 0) {  // No 2:3 subsampling or other weirdness.
 136                 fprintf(stderr, "Unsupported subsampling scheme. (Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
 137                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
 138                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
 139                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
 140                 abort();
 141         }
 142         dinfo.raw_data_out = true;
 143
 144         if (!error_mgr.run([&dinfo] {
 145                     jpeg_start_decompress(&dinfo);
 146             })) {
 147                 return get_black_frame();
 148         }
 149
 150         frame->width = dinfo.output_width;
 151         frame->height = dinfo.output_height;
 152         frame->chroma_subsampling_x = dinfo.max_h_samp_factor / dinfo.comp_info[1].h_samp_factor;
 153         frame->chroma_subsampling_y = dinfo.max_v_samp_factor / dinfo.comp_info[1].v_samp_factor;
 154
 155         unsigned h_mcu_size = DCTSIZE * dinfo.max_h_samp_factor;
 156         unsigned v_mcu_size = DCTSIZE * dinfo.max_v_samp_factor;
 157         unsigned mcu_width_blocks = (dinfo.output_width + h_mcu_size - 1) / h_mcu_size;
 158         unsigned mcu_height_blocks = (dinfo.output_height + v_mcu_size - 1) / v_mcu_size;
 159
 160         unsigned luma_width_blocks = mcu_width_blocks * dinfo.comp_info[0].h_samp_factor;
 161         unsigned chroma_width_blocks = mcu_width_blocks * dinfo.comp_info[1].h_samp_factor;
 162         unsigned luma_height_blocks = mcu_height_blocks * dinfo.comp_info[0].v_samp_factor;
 163         unsigned chroma_height_blocks = mcu_height_blocks * dinfo.comp_info[1].v_samp_factor;
 164
 165         // TODO: Decode into a PBO.
 166         frame->y.reset(new uint8_t[luma_width_blocks * luma_height_blocks * DCTSIZE2]);
 167         frame->cb.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
 168         frame->cr.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
 169         frame->pitch_y = luma_width_blocks * DCTSIZE;
 170         frame->pitch_chroma = chroma_width_blocks * DCTSIZE;
 171
 172         if (dinfo.marker_list != nullptr &&
 173             dinfo.marker_list->marker == JPEG_APP0 + 1 &&
 174             dinfo.marker_list->data_length >= 4 &&
 175             memcmp(dinfo.marker_list->data, "Exif", 4) == 0) {
 176                 frame->exif_data.assign(reinterpret_cast<char *>(dinfo.marker_list->data),
 177                         dinfo.marker_list->data_length);
 178         }
 179
 180         if (!error_mgr.run([&dinfo, &frame, v_mcu_size, mcu_height_blocks] {
 181                     JSAMPROW yptr[v_mcu_size], cbptr[v_mcu_size], crptr[v_mcu_size];
 182                     JSAMPARRAY data[3] = { yptr, cbptr, crptr };
 183                     for (unsigned y = 0; y < mcu_height_blocks; ++y) {
 184                             // NOTE: The last elements of cbptr/crptr will be unused for vertically subsampled chroma.
 185                             for (unsigned yy = 0; yy < v_mcu_size; ++yy) {
 186                                     yptr[yy] = frame->y.get() + (y * DCTSIZE * dinfo.max_v_samp_factor + yy) * frame->pitch_y;
 187                                     cbptr[yy] = frame->cb.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * frame->pitch_chroma;
 188                                     crptr[yy] = frame->cr.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * frame->pitch_chroma;
 189                             }
 190
 191                             jpeg_read_raw_data(&dinfo, data, v_mcu_size);
 192                     }
 193
 194                     (void)jpeg_finish_decompress(&dinfo);
 195             })) {
 196                 return get_black_frame();
 197         }
 198
 199         ++metric_jpeg_software_decode_frames;
 200         steady_clock::time_point stop = steady_clock::now();
 201         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
 202         return frame;
 203 }
 204
 205 void prune_cache()
 206 {
 207         // Assumes cache_mu is held.
 208         int64_t bytes_still_to_remove = cache_bytes_used - (size_t(CACHE_SIZE_MB) * 1024 * 1024) * 9 / 10;
 209         if (bytes_still_to_remove <= 0)
 210                 return;
 211
 212         vector<pair<size_t, size_t>> lru_timestamps_and_size;
 213         for (const auto &key_and_value : cache) {
 214                 lru_timestamps_and_size.emplace_back(
 215                         key_and_value.second.last_used,
 216                         frame_size(*key_and_value.second.frame));
 217         }
 218         sort(lru_timestamps_and_size.begin(), lru_timestamps_and_size.end());
 219
 220         // Remove the oldest ones until we are below 90% of the cache used.
 221         size_t lru_cutoff_point = 0;
 222         for (const pair<size_t, size_t> &it : lru_timestamps_and_size) {
 223                 lru_cutoff_point = it.first;
 224                 bytes_still_to_remove -= it.second;
 225                 if (bytes_still_to_remove <= 0)
 226                         break;
 227         }
 228
 229         for (auto it = cache.begin(); it != cache.end();) {
 230                 if (it->second.last_used <= lru_cutoff_point) {
 231                         cache_bytes_used -= frame_size(*it->second.frame);
 232                         metric_jpeg_cache_used_bytes = cache_bytes_used;
 233                         it = cache.erase(it);
 234                 } else {
 235                         ++it;
 236                 }
 237         }
 238 }
 239
 240 shared_ptr<Frame> decode_jpeg_with_cache(FrameOnDisk frame_spec, CacheMissBehavior cache_miss_behavior, FrameReader *frame_reader, bool *did_decode)
 241 {
 242         *did_decode = false;
 243         {
 244                 lock_guard<mutex> lock(cache_mu);
 245                 auto it = cache.find(frame_spec);
 246                 if (it != cache.end()) {
 247                         ++metric_jpeg_cache_hit_frames;
 248                         it->second.last_used = event_counter++;
 249                         return it->second.frame;
 250                 }
 251         }
 252
 253         if (cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE) {
 254                 ++metric_jpeg_cache_given_up_frames;
 255                 return nullptr;
 256         }
 257
 258         ++metric_jpeg_cache_miss_frames;
 259
 260         *did_decode = true;
 261         shared_ptr<Frame> frame = decode_jpeg(frame_reader->read_frame(frame_spec, /*read_video=*/true, /*read_audio=*/false).video);
 262
 263         lock_guard<mutex> lock(cache_mu);
 264         cache_bytes_used += frame_size(*frame);
 265         metric_jpeg_cache_used_bytes = cache_bytes_used;
 266         cache[frame_spec] = LRUFrame{ frame, event_counter++ };
 267
 268         if (cache_bytes_used > size_t(CACHE_SIZE_MB) * 1024 * 1024) {
 269                 prune_cache();
 270         }
 271         return frame;
 272 }
 273
 274 void JPEGFrameView::jpeg_decoder_thread_func()
 275 {
 276         size_t num_decoded = 0, num_dropped = 0;
 277
 278         pthread_setname_np(pthread_self(), "JPEGDecoder");
 279         while (!should_quit.load()) {
 280                 PendingDecode decode;
 281                 CacheMissBehavior cache_miss_behavior = DECODE_IF_NOT_IN_CACHE;
 282                 {
 283                         unique_lock<mutex> lock(cache_mu);  // TODO: Perhaps under another lock?
 284                         any_pending_decodes.wait(lock, [this] {
 285                                 return !pending_decodes.empty() || should_quit.load();
 286                         });
 287                         if (should_quit.load())
 288                                 break;
 289                         decode = pending_decodes.front();
 290                         pending_decodes.pop_front();
 291
 292                         if (pending_decodes.size() > 3) {
 293                                 cache_miss_behavior = RETURN_NULLPTR_IF_NOT_IN_CACHE;
 294                         }
 295                 }
 296
 297                 if (decode.frame != nullptr) {
 298                         // Already decoded, so just show it.
 299                         setDecodedFrame(decode.frame, nullptr, 1.0f);
 300                         continue;
 301                 }
 302
 303                 shared_ptr<Frame> primary_frame, secondary_frame;
 304                 bool drop = false;
 305                 for (int subframe_idx = 0; subframe_idx < 2; ++subframe_idx) {
 306                         const FrameOnDisk &frame_spec = (subframe_idx == 0 ? decode.primary : decode.secondary);
 307                         if (frame_spec.pts == -1) {
 308                                 // No secondary frame.
 309                                 continue;
 310                         }
 311
 312                         bool found_in_cache;
 313                         shared_ptr<Frame> frame = decode_jpeg_with_cache(frame_spec, cache_miss_behavior, &frame_reader, &found_in_cache);
 314
 315                         if (frame == nullptr) {
 316                                 assert(cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE);
 317                                 drop = true;
 318                                 break;
 319                         }
 320
 321                         if (!found_in_cache) {
 322                                 ++num_decoded;
 323                                 if (num_decoded % 1000 == 0) {
 324                                         fprintf(stderr, "Decoded %zu images, dropped %zu (%.2f%% dropped)\n",
 325                                                 num_decoded, num_dropped, (100.0 * num_dropped) / (num_decoded + num_dropped));
 326                                 }
 327                         }
 328                         if (subframe_idx == 0) {
 329                                 primary_frame = std::move(frame);
 330                         } else {
 331                                 secondary_frame = std::move(frame);
 332                         }
 333                 }
 334                 if (drop) {
 335                         ++num_dropped;
 336                         continue;
 337                 }
 338
 339                 // TODO: Could we get jitter between non-interpolated and interpolated frames here?
 340                 setDecodedFrame(primary_frame, secondary_frame, decode.fade_alpha);
 341         }
 342 }
 343
 344 JPEGFrameView::~JPEGFrameView()
 345 {
 346         any_pending_decodes.notify_all();
 347         jpeg_decoder_thread.join();
 348 }
 349
 350 JPEGFrameView::JPEGFrameView(QWidget *parent)
 351         : QGLWidget(parent, global_share_widget)
 352 {
 353         call_once(jpeg_metrics_inited, [] {
 354                 global_metrics.add("jpeg_cache_used_bytes", &metric_jpeg_cache_used_bytes, Metrics::TYPE_GAUGE);
 355                 global_metrics.add("jpeg_cache_limit_bytes", &metric_jpeg_cache_limit_bytes, Metrics::TYPE_GAUGE);
 356                 global_metrics.add("jpeg_cache_frames", { { "action", "given_up" } }, &metric_jpeg_cache_given_up_frames);
 357                 global_metrics.add("jpeg_cache_frames", { { "action", "hit" } }, &metric_jpeg_cache_hit_frames);
 358                 global_metrics.add("jpeg_cache_frames", { { "action", "miss" } }, &metric_jpeg_cache_miss_frames);
 359                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "decode" } }, &metric_jpeg_software_decode_frames);
 360                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "fail" } }, &metric_jpeg_software_fail_frames);
 361                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "decode" } }, &metric_jpeg_vaapi_decode_frames);
 362                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "fail" } }, &metric_jpeg_vaapi_fail_frames);
 363                 global_metrics.add("jpeg_frames", { { "action", "prepared" } }, &metric_jpeg_prepared_frames);
 364                 global_metrics.add("jpeg_frames", { { "action", "displayed" } }, &metric_jpeg_displayed_frames);
 365                 vector<double> quantiles{ 0.01, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99 };
 366                 metric_jpeg_decode_time_seconds.init(quantiles, 60.0);
 367                 global_metrics.add("jpeg_decode_time_seconds", &metric_jpeg_decode_time_seconds);
 368         });
 369 }
 370
 371 void JPEGFrameView::setFrame(unsigned stream_idx, FrameOnDisk frame, FrameOnDisk secondary_frame, float fade_alpha)
 372 {
 373         current_stream_idx = stream_idx;  // TODO: Does this interact with fades?
 374
 375         lock_guard<mutex> lock(cache_mu);
 376         PendingDecode decode;
 377         decode.primary = frame;
 378         decode.secondary = secondary_frame;
 379         decode.fade_alpha = fade_alpha;
 380         pending_decodes.push_back(decode);
 381         any_pending_decodes.notify_all();
 382 }
 383
 384 void JPEGFrameView::setFrame(shared_ptr<Frame> frame)
 385 {
 386         lock_guard<mutex> lock(cache_mu);
 387         PendingDecode decode;
 388         decode.frame = std::move(frame);
 389         pending_decodes.push_back(decode);
 390         any_pending_decodes.notify_all();
 391 }
 392
 393 void JPEGFrameView::initializeGL()
 394 {
 395         glDisable(GL_BLEND);
 396         glDisable(GL_DEPTH_TEST);
 397         check_error();
 398
 399         resource_pool = new ResourcePool;
 400         jpeg_decoder_thread = std::thread(&JPEGFrameView::jpeg_decoder_thread_func, this);
 401
 402         ycbcr_converter.reset(new YCbCrConverter(YCbCrConverter::OUTPUT_TO_RGBA, resource_pool));
 403
 404         ImageFormat inout_format;
 405         inout_format.color_space = COLORSPACE_sRGB;
 406         inout_format.gamma_curve = GAMMA_sRGB;
 407
 408         overlay_chain.reset(new EffectChain(overlay_base_width, overlay_base_height, resource_pool));
 409         overlay_input = (movit::FlatInput *)overlay_chain->add_input(new FlatInput(inout_format, FORMAT_GRAYSCALE, GL_UNSIGNED_BYTE, overlay_base_width, overlay_base_height));
 410
 411         overlay_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
 412         overlay_chain->finalize();
 413 }
 414
 415 void JPEGFrameView::resizeGL(int width, int height)
 416 {
 417         check_error();
 418         glViewport(0, 0, width, height);
 419         check_error();
 420
 421         // Save these, as width() and height() will lie with DPI scaling.
 422         gl_width = width;
 423         gl_height = height;
 424 }
 425
 426 void JPEGFrameView::paintGL()
 427 {
 428         glViewport(0, 0, gl_width, gl_height);
 429         if (current_frame == nullptr) {
 430                 glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
 431                 glClear(GL_COLOR_BUFFER_BIT);
 432                 return;
 433         }
 434
 435         if (!displayed_this_frame) {
 436                 ++metric_jpeg_displayed_frames;
 437                 displayed_this_frame = true;
 438         }
 439
 440         check_error();
 441         current_chain->render_to_screen();
 442
 443         if (overlay_image != nullptr) {
 444                 if (overlay_input_needs_refresh) {
 445                         overlay_input->set_width(overlay_width);
 446                         overlay_input->set_height(overlay_height);
 447                         overlay_input->set_pixel_data(overlay_image->bits());
 448                         overlay_input_needs_refresh = false;
 449                 }
 450                 glViewport(gl_width - overlay_width, 0, overlay_width, overlay_height);
 451                 overlay_chain->render_to_screen();
 452         }
 453 }
 454
 455 namespace {
 456
 457 }  // namespace
 458
 459 void JPEGFrameView::setDecodedFrame(shared_ptr<Frame> frame, shared_ptr<Frame> secondary_frame, float fade_alpha)
 460 {
 461         post_to_main_thread([this, frame, secondary_frame, fade_alpha] {
 462                 current_frame = frame;
 463                 current_secondary_frame = secondary_frame;
 464
 465                 if (secondary_frame != nullptr) {
 466                         current_chain = ycbcr_converter->prepare_chain_for_fade(frame, secondary_frame, fade_alpha);
 467                 } else {
 468                         current_chain = ycbcr_converter->prepare_chain_for_conversion(frame);
 469                 }
 470                 ++metric_jpeg_prepared_frames;
 471                 displayed_this_frame = false;
 472                 update();
 473         });
 474 }
 475
 476 void JPEGFrameView::mousePressEvent(QMouseEvent *event)
 477 {
 478         if (event->type() == QEvent::MouseButtonPress && event->button() == Qt::LeftButton) {
 479                 emit clicked();
 480         }
 481 }
 482
 483 void JPEGFrameView::set_overlay(const string &text)
 484 {
 485         if (text.empty()) {
 486                 overlay_image.reset();
 487                 return;
 488         }
 489
 490         // Figure out how large the texture needs to be.
 491         {
 492                 QImage img(overlay_width, overlay_height, QImage::Format_Grayscale8);
 493                 QPainter painter(&img);
 494                 QFont font = painter.font();
 495                 font.setPointSize(12);
 496                 QFontMetrics metrics(font);
 497                 overlay_base_width = lrint(metrics.boundingRect(QString::fromStdString(text)).width() + 8.0);
 498                 overlay_base_height = lrint(metrics.height());
 499         }
 500
 501         float dpr = QGuiApplication::primaryScreen()->devicePixelRatio();
 502         overlay_width = lrint(overlay_base_width * dpr);
 503         overlay_height = lrint(overlay_base_height * dpr);
 504
 505         // Work around OpenGL alignment issues.
 506         while (overlay_width % 4 != 0) ++overlay_width;
 507
 508         // Now do the actual drawing.
 509         overlay_image.reset(new QImage(overlay_width, overlay_height, QImage::Format_Grayscale8));
 510         overlay_image->setDevicePixelRatio(dpr);
 511         overlay_image->fill(0);
 512         QPainter painter(overlay_image.get());
 513
 514         painter.setPen(Qt::white);
 515         QFont font = painter.font();
 516         font.setPointSize(12);
 517         painter.setFont(font);
 518
 519         painter.drawText(QRectF(0, 0, overlay_base_width, overlay_base_height), Qt::AlignCenter, QString::fromStdString(text));
 520
 521         // Don't refresh immediately; we might not have an OpenGL context here.
 522         overlay_input_needs_refresh = true;
 523 }
 524
 525 shared_ptr<Frame> get_black_frame()
 526 {
 527         static shared_ptr<Frame> black_frame;
 528         static once_flag flag;
 529         call_once(flag, [] {
 530                 black_frame.reset(new Frame);
 531                 black_frame->y.reset(new uint8_t[global_flags.width * global_flags.height]);
 532                 black_frame->cb.reset(new uint8_t[(global_flags.width / 2) * (global_flags.height / 2)]);
 533                 black_frame->cr.reset(new uint8_t[(global_flags.width / 2) * (global_flags.height / 2)]);
 534                 black_frame->width = global_flags.width;
 535                 black_frame->height = global_flags.height;
 536                 black_frame->chroma_subsampling_x = 2;
 537                 black_frame->chroma_subsampling_y = 2;
 538                 black_frame->pitch_y = global_flags.width;
 539                 black_frame->pitch_chroma = global_flags.width / 2;
 540         });
 541         ++metric_jpeg_software_fail_frames;
 542         return black_frame;
 543 }