]> git.sesse.net Git - nageru/blob - futatabi/jpeg_frame_view.cpp
Fix a Clang 19 warning.
[nageru] / 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 "pbo_pool.h"
8 #include "shared/context.h"
9 #include "shared/metrics.h"
10 #include "shared/post_to_main_thread.h"
11 #include "video_stream.h"
12 #include "ycbcr_converter.h"
13
14 #include <QMouseEvent>
15 #include <QScreen>
16 #include <atomic>
17 #include <chrono>
18 #include <condition_variable>
19 #include <deque>
20 #include <jpeglib.h>
21 #include <movit/init.h>
22 #include <movit/resource_pool.h>
23 #include <movit/util.h>
24 #include <mutex>
25 #include <stdint.h>
26 #include <thread>
27 #include <unistd.h>
28 #include <utility>
29
30 // Must come after the Qt stuff.
31 #include "vaapi_jpeg_decoder.h"
32
33 using namespace movit;
34 using namespace std;
35 using namespace std::chrono;
36
37 namespace {
38
39 // Just an arbitrary order for std::map.
40 struct FrameOnDiskLexicalOrder {
41         bool operator()(const FrameOnDisk &a, const FrameOnDisk &b) const
42         {
43                 if (a.pts != b.pts)
44                         return a.pts < b.pts;
45                 if (a.offset != b.offset)
46                         return a.offset < b.offset;
47                 if (a.filename_idx != b.filename_idx)
48                         return a.filename_idx < b.filename_idx;
49                 assert(a.size == b.size);
50                 return false;
51         }
52 };
53
54 inline size_t frame_size(const Frame &frame)
55 {
56         size_t y_size = frame.width * frame.height;
57         size_t cbcr_size = y_size / frame.chroma_subsampling_x / frame.chroma_subsampling_y;
58         return y_size + cbcr_size * 2;
59 }
60
61 struct LRUFrame {
62         shared_ptr<Frame> frame;
63         size_t last_used;
64 };
65
66 // There can be multiple JPEGFrameView instances, so make all the metrics static.
67 once_flag jpeg_metrics_inited;
68 atomic<int64_t> metric_jpeg_cache_used_bytes{ 0 };  // Same value as cache_bytes_used.
69 atomic<int64_t> metric_jpeg_cache_limit_bytes{ size_t(CACHE_SIZE_MB) * 1024 * 1024 };
70 atomic<int64_t> metric_jpeg_cache_given_up_frames{ 0 };
71 atomic<int64_t> metric_jpeg_cache_hit_frames{ 0 };
72 atomic<int64_t> metric_jpeg_cache_miss_frames{ 0 };
73 atomic<int64_t> metric_jpeg_software_decode_frames{ 0 };
74 atomic<int64_t> metric_jpeg_software_fail_frames{ 0 };
75 atomic<int64_t> metric_jpeg_vaapi_decode_frames{ 0 };
76 atomic<int64_t> metric_jpeg_vaapi_fail_frames{ 0 };
77 atomic<int64_t> metric_jpeg_prepared_frames{ 0 };
78 atomic<int64_t> metric_jpeg_displayed_frames{ 0 };
79 Summary metric_jpeg_decode_time_seconds;
80
81 }  // namespace
82
83 mutex cache_mu;
84 map<FrameOnDisk, LRUFrame, FrameOnDiskLexicalOrder> cache;  // Under cache_mu.
85 size_t cache_bytes_used = 0;  // Under cache_mu.
86 atomic<size_t> event_counter{ 0 };
87 extern QGLWidget *global_share_widget;
88 extern atomic<bool> should_quit;
89
90 shared_ptr<Frame> decode_jpeg(const string &jpeg)
91 {
92         steady_clock::time_point start = steady_clock::now();
93         shared_ptr<Frame> frame;
94         if (vaapi_jpeg_decoding_usable) {
95                 frame = decode_jpeg_vaapi(jpeg);
96                 if (frame != nullptr) {
97                         ++metric_jpeg_vaapi_decode_frames;
98                         steady_clock::time_point stop = steady_clock::now();
99                         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
100                         return frame;
101                 }
102                 fprintf(stderr, "VA-API hardware decoding failed; falling back to software.\n");
103                 ++metric_jpeg_vaapi_fail_frames;
104         }
105
106         frame.reset(new Frame);
107
108         jpeg_decompress_struct dinfo;
109         JPEGWrapErrorManager error_mgr(&dinfo);
110         if (!error_mgr.run([&dinfo] { jpeg_create_decompress(&dinfo); })) {
111                 return get_black_frame();
112         }
113         JPEGDestroyer destroy_dinfo(&dinfo);
114
115         jpeg_save_markers(&dinfo, JPEG_APP0 + 1, 0xFFFF);
116
117         if (!error_mgr.run([&dinfo, &jpeg] {
118                     jpeg_mem_src(&dinfo, reinterpret_cast<const unsigned char *>(jpeg.data()), jpeg.size());
119                     jpeg_read_header(&dinfo, true);
120             })) {
121                 return get_black_frame();
122         }
123
124         if (dinfo.num_components != 3) {
125                 fprintf(stderr, "Not a color JPEG. (%d components, Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
126                         dinfo.num_components,
127                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
128                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
129                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
130                 return get_black_frame();
131         }
132         if (dinfo.comp_info[0].h_samp_factor != dinfo.max_h_samp_factor ||
133             dinfo.comp_info[0].v_samp_factor != dinfo.max_v_samp_factor ||  // Y' must not be subsampled.
134             dinfo.comp_info[1].h_samp_factor != dinfo.comp_info[2].h_samp_factor ||
135             dinfo.comp_info[1].v_samp_factor != dinfo.comp_info[2].v_samp_factor ||  // Cb and Cr must be identically subsampled.
136             (dinfo.max_h_samp_factor % dinfo.comp_info[1].h_samp_factor) != 0 ||
137             (dinfo.max_v_samp_factor % dinfo.comp_info[1].v_samp_factor) != 0) {  // No 2:3 subsampling or other weirdness.
138                 fprintf(stderr, "Unsupported subsampling scheme. (Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
139                         dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
140                         dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
141                         dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
142                 abort();
143         }
144         dinfo.raw_data_out = true;
145
146         if (!error_mgr.run([&dinfo] {
147                     jpeg_start_decompress(&dinfo);
148             })) {
149                 return get_black_frame();
150         }
151
152         frame->width = dinfo.output_width;
153         frame->height = dinfo.output_height;
154         frame->chroma_subsampling_x = dinfo.max_h_samp_factor / dinfo.comp_info[1].h_samp_factor;
155         frame->chroma_subsampling_y = dinfo.max_v_samp_factor / dinfo.comp_info[1].v_samp_factor;
156
157         unsigned h_mcu_size = DCTSIZE * dinfo.max_h_samp_factor;
158         unsigned v_mcu_size = DCTSIZE * dinfo.max_v_samp_factor;
159         unsigned mcu_width_blocks = (dinfo.output_width + h_mcu_size - 1) / h_mcu_size;
160         unsigned mcu_height_blocks = (dinfo.output_height + v_mcu_size - 1) / v_mcu_size;
161
162         unsigned luma_width_blocks = mcu_width_blocks * dinfo.comp_info[0].h_samp_factor;
163         unsigned chroma_width_blocks = mcu_width_blocks * dinfo.comp_info[1].h_samp_factor;
164
165         PBO pbo = global_pbo_pool->alloc_pbo();
166         const size_t chroma_width = dinfo.image_width / frame->chroma_subsampling_x;
167         const size_t chroma_height = dinfo.image_height / frame->chroma_subsampling_y;
168         size_t cb_offset = dinfo.image_width * dinfo.image_height;
169         size_t cr_offset = cb_offset + chroma_width * chroma_height;
170         uint8_t *y_pix = pbo.ptr;
171         uint8_t *cb_pix = pbo.ptr + cb_offset;
172         uint8_t *cr_pix = pbo.ptr + cr_offset;
173         unsigned pitch_y = luma_width_blocks * DCTSIZE;
174         unsigned pitch_chroma = chroma_width_blocks * DCTSIZE;
175
176         if (dinfo.marker_list != nullptr &&
177             dinfo.marker_list->marker == JPEG_APP0 + 1 &&
178             dinfo.marker_list->data_length >= 4 &&
179             memcmp(dinfo.marker_list->data, "Exif", 4) == 0) {
180                 frame->exif_data.assign(reinterpret_cast<char *>(dinfo.marker_list->data),
181                         dinfo.marker_list->data_length);
182         }
183
184         if (!error_mgr.run([&dinfo, &y_pix, &cb_pix, &cr_pix, pitch_y, pitch_chroma, v_mcu_size, mcu_height_blocks] {
185                     unique_ptr<JSAMPROW[]> yptr(new JSAMPROW[v_mcu_size]);
186                     unique_ptr<JSAMPROW[]> cbptr(new JSAMPROW[v_mcu_size]);
187                     unique_ptr<JSAMPROW[]> crptr(new JSAMPROW[v_mcu_size]);
188                     JSAMPARRAY data[3] = { yptr.get(), cbptr.get(), crptr.get() };
189                     for (unsigned y = 0; y < mcu_height_blocks; ++y) {
190                             // NOTE: The last elements of cbptr/crptr will be unused for vertically subsampled chroma.
191                             for (unsigned yy = 0; yy < v_mcu_size; ++yy) {
192                                     yptr[yy] = y_pix + (y * DCTSIZE * dinfo.max_v_samp_factor + yy) * pitch_y;
193                                     cbptr[yy] = cb_pix + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * pitch_chroma;
194                                     crptr[yy] = cr_pix + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * pitch_chroma;
195                             }
196
197                             jpeg_read_raw_data(&dinfo, data, v_mcu_size);
198                     }
199
200                     (void)jpeg_finish_decompress(&dinfo);
201             })) {
202                 return get_black_frame();
203         }
204
205         // FIXME: what about resolutions that are not divisible by the block factor?
206         glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo.pbo);
207         frame->y = create_texture_2d(frame->width, frame->height, GL_R8, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
208         frame->cb = create_texture_2d(chroma_width, chroma_height, GL_R8, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cb_offset));
209         frame->cr = create_texture_2d(chroma_width, chroma_height, GL_R8, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cr_offset));
210         glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
211
212         glFlushMappedNamedBufferRange(pbo.pbo, 0, dinfo.image_width * dinfo.image_height + chroma_width * chroma_height * 2);
213         glMemoryBarrier(GL_PIXEL_BUFFER_BARRIER_BIT);
214         pbo.upload_done = RefCountedGLsync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
215         glFlush();
216         frame->uploaded_ui_thread = pbo.upload_done;
217         frame->uploaded_interpolation = pbo.upload_done;
218         global_pbo_pool->release_pbo(move(pbo));
219
220         ++metric_jpeg_software_decode_frames;
221         steady_clock::time_point stop = steady_clock::now();
222         metric_jpeg_decode_time_seconds.count_event(duration<double>(stop - start).count());
223         return frame;
224 }
225
226 void prune_cache()
227 {
228         // Assumes cache_mu is held.
229         int64_t bytes_still_to_remove = cache_bytes_used - (size_t(CACHE_SIZE_MB) * 1024 * 1024) * 9 / 10;
230         if (bytes_still_to_remove <= 0)
231                 return;
232
233         vector<pair<size_t, size_t>> lru_timestamps_and_size;
234         for (const auto &key_and_value : cache) {
235                 lru_timestamps_and_size.emplace_back(
236                         key_and_value.second.last_used,
237                         frame_size(*key_and_value.second.frame));
238         }
239         sort(lru_timestamps_and_size.begin(), lru_timestamps_and_size.end());
240
241         // Remove the oldest ones until we are below 90% of the cache used.
242         size_t lru_cutoff_point = 0;
243         for (const pair<size_t, size_t> &it : lru_timestamps_and_size) {
244                 lru_cutoff_point = it.first;
245                 bytes_still_to_remove -= it.second;
246                 if (bytes_still_to_remove <= 0)
247                         break;
248         }
249
250         for (auto it = cache.begin(); it != cache.end();) {
251                 if (it->second.last_used <= lru_cutoff_point) {
252                         cache_bytes_used -= frame_size(*it->second.frame);
253                         metric_jpeg_cache_used_bytes = cache_bytes_used;
254                         it = cache.erase(it);
255                 } else {
256                         ++it;
257                 }
258         }
259 }
260
261 shared_ptr<Frame> decode_jpeg_with_cache(FrameOnDisk frame_spec, CacheMissBehavior cache_miss_behavior, FrameReader *frame_reader, bool *did_decode)
262 {
263         *did_decode = false;
264         {
265                 lock_guard<mutex> lock(cache_mu);
266                 auto it = cache.find(frame_spec);
267                 if (it != cache.end()) {
268                         ++metric_jpeg_cache_hit_frames;
269                         it->second.last_used = event_counter++;
270                         return it->second.frame;
271                 }
272         }
273
274         if (cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE) {
275                 ++metric_jpeg_cache_given_up_frames;
276                 return nullptr;
277         }
278
279         ++metric_jpeg_cache_miss_frames;
280
281         *did_decode = true;
282         shared_ptr<Frame> frame = decode_jpeg(frame_reader->read_frame(frame_spec, /*read_video=*/true, /*read_audio=*/false).video);
283
284         lock_guard<mutex> lock(cache_mu);
285         cache_bytes_used += frame_size(*frame);
286         metric_jpeg_cache_used_bytes = cache_bytes_used;
287         cache[frame_spec] = LRUFrame{ frame, event_counter++ };
288
289         if (cache_bytes_used > size_t(CACHE_SIZE_MB) * 1024 * 1024) {
290                 prune_cache();
291         }
292         return frame;
293 }
294
295 void JPEGFrameView::jpeg_decoder_thread_func()
296 {
297         size_t num_decoded = 0, num_dropped = 0;
298
299         pthread_setname_np(pthread_self(), "JPEGDecoder");
300         QSurface *surface = create_surface();
301         QOpenGLContext *context = create_context(surface);
302         bool ok = make_current(context, surface);
303         if (!ok) {
304                 fprintf(stderr, "Video stream couldn't get an OpenGL context\n");
305                 abort();
306         }
307         while (!should_quit.load()) {
308                 PendingDecode decode;
309                 CacheMissBehavior cache_miss_behavior = DECODE_IF_NOT_IN_CACHE;
310                 {
311                         unique_lock<mutex> lock(cache_mu);  // TODO: Perhaps under another lock?
312                         any_pending_decodes.wait(lock, [this] {
313                                 return !pending_decodes.empty() || should_quit.load();
314                         });
315                         if (should_quit.load())
316                                 break;
317                         decode = pending_decodes.front();
318                         pending_decodes.pop_front();
319
320                         if (pending_decodes.size() > 3) {
321                                 cache_miss_behavior = RETURN_NULLPTR_IF_NOT_IN_CACHE;
322                         }
323                 }
324
325                 if (decode.frame != nullptr) {
326                         // Already decoded, so just show it.
327                         setDecodedFrame(decode.frame, nullptr, 1.0f);
328                         continue;
329                 }
330
331                 shared_ptr<Frame> primary_frame, secondary_frame;
332                 bool drop = false;
333                 for (int subframe_idx = 0; subframe_idx < 2; ++subframe_idx) {
334                         const FrameOnDisk &frame_spec = (subframe_idx == 0 ? decode.primary : decode.secondary);
335                         if (frame_spec.pts == -1) {
336                                 // No secondary frame.
337                                 continue;
338                         }
339
340                         bool found_in_cache;
341                         shared_ptr<Frame> frame = decode_jpeg_with_cache(frame_spec, cache_miss_behavior, &frame_reader, &found_in_cache);
342
343                         if (frame == nullptr) {
344                                 assert(cache_miss_behavior == RETURN_NULLPTR_IF_NOT_IN_CACHE);
345                                 drop = true;
346                                 break;
347                         }
348
349                         if (!found_in_cache) {
350                                 ++num_decoded;
351                                 if (num_decoded % 1000 == 0) {
352                                         fprintf(stderr, "Decoded %zu images, dropped %zu (%.2f%% dropped)\n",
353                                                 num_decoded, num_dropped, (100.0 * num_dropped) / (num_decoded + num_dropped));
354                                 }
355                         }
356                         if (subframe_idx == 0) {
357                                 primary_frame = std::move(frame);
358                         } else {
359                                 secondary_frame = std::move(frame);
360                         }
361                 }
362                 if (drop) {
363                         ++num_dropped;
364                         continue;
365                 }
366
367                 // TODO: Could we get jitter between non-interpolated and interpolated frames here?
368                 setDecodedFrame(primary_frame, secondary_frame, decode.fade_alpha);
369         }
370 }
371
372 JPEGFrameView::~JPEGFrameView()
373 {
374         any_pending_decodes.notify_all();
375         jpeg_decoder_thread.join();
376 }
377
378 JPEGFrameView::JPEGFrameView(QWidget *parent)
379         : QGLWidget(parent, global_share_widget)
380 {
381         call_once(jpeg_metrics_inited, [] {
382                 global_metrics.add("jpeg_cache_used_bytes", &metric_jpeg_cache_used_bytes, Metrics::TYPE_GAUGE);
383                 global_metrics.add("jpeg_cache_limit_bytes", &metric_jpeg_cache_limit_bytes, Metrics::TYPE_GAUGE);
384                 global_metrics.add("jpeg_cache_frames", { { "action", "given_up" } }, &metric_jpeg_cache_given_up_frames);
385                 global_metrics.add("jpeg_cache_frames", { { "action", "hit" } }, &metric_jpeg_cache_hit_frames);
386                 global_metrics.add("jpeg_cache_frames", { { "action", "miss" } }, &metric_jpeg_cache_miss_frames);
387                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "decode" } }, &metric_jpeg_software_decode_frames);
388                 global_metrics.add("jpeg_decode_frames", { { "decoder", "software" }, { "result", "fail" } }, &metric_jpeg_software_fail_frames);
389                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "decode" } }, &metric_jpeg_vaapi_decode_frames);
390                 global_metrics.add("jpeg_decode_frames", { { "decoder", "vaapi" }, { "result", "fail" } }, &metric_jpeg_vaapi_fail_frames);
391                 global_metrics.add("jpeg_frames", { { "action", "prepared" } }, &metric_jpeg_prepared_frames);
392                 global_metrics.add("jpeg_frames", { { "action", "displayed" } }, &metric_jpeg_displayed_frames);
393                 vector<double> quantiles{ 0.01, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99 };
394                 metric_jpeg_decode_time_seconds.init(quantiles, 60.0);
395                 global_metrics.add("jpeg_decode_time_seconds", &metric_jpeg_decode_time_seconds);
396         });
397 }
398
399 void JPEGFrameView::setFrame(unsigned stream_idx, FrameOnDisk frame, FrameOnDisk secondary_frame, float fade_alpha)
400 {
401         current_stream_idx = stream_idx;  // TODO: Does this interact with fades?
402
403         lock_guard<mutex> lock(cache_mu);
404         PendingDecode decode;
405         decode.primary = frame;
406         decode.secondary = secondary_frame;
407         decode.fade_alpha = fade_alpha;
408         pending_decodes.push_back(decode);
409         any_pending_decodes.notify_all();
410 }
411
412 void JPEGFrameView::setFrame(shared_ptr<Frame> frame)
413 {
414         lock_guard<mutex> lock(cache_mu);
415         PendingDecode decode;
416         decode.frame = std::move(frame);
417         decode.fade_alpha = 0.0f;
418         pending_decodes.push_back(decode);
419         any_pending_decodes.notify_all();
420 }
421
422 void JPEGFrameView::initializeGL()
423 {
424         init_pbo_pool();
425
426         glDisable(GL_BLEND);
427         glDisable(GL_DEPTH_TEST);
428         check_error();
429
430         resource_pool = new ResourcePool;
431         jpeg_decoder_thread = std::thread(&JPEGFrameView::jpeg_decoder_thread_func, this);
432
433         ycbcr_converter.reset(new YCbCrConverter(YCbCrConverter::OUTPUT_TO_RGBA, resource_pool));
434
435         ImageFormat inout_format;
436         inout_format.color_space = COLORSPACE_sRGB;
437         inout_format.gamma_curve = GAMMA_sRGB;
438
439         overlay_chain.reset(new EffectChain(overlay_base_width, overlay_base_height, resource_pool));
440         overlay_input = (movit::FlatInput *)overlay_chain->add_input(new FlatInput(inout_format, FORMAT_GRAYSCALE, GL_UNSIGNED_BYTE, overlay_base_width, overlay_base_height));
441
442         overlay_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
443         overlay_chain->finalize();
444 }
445
446 void JPEGFrameView::resizeGL(int width, int height)
447 {
448         check_error();
449         glViewport(0, 0, width, height);
450         check_error();
451
452         // Save these, as width() and height() will lie with DPI scaling.
453         gl_width = width;
454         gl_height = height;
455 }
456
457 void JPEGFrameView::paintGL()
458 {
459         glViewport(0, 0, gl_width, gl_height);
460         if (current_frame == nullptr) {
461                 glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
462                 glClear(GL_COLOR_BUFFER_BIT);
463                 return;
464         }
465
466         if (!displayed_this_frame) {
467                 ++metric_jpeg_displayed_frames;
468                 displayed_this_frame = true;
469         }
470         if (current_frame->uploaded_ui_thread != nullptr) {
471                 glWaitSync(current_frame->uploaded_ui_thread.get(), /*flags=*/0, GL_TIMEOUT_IGNORED);
472                 current_frame->uploaded_ui_thread.reset();
473         }
474         if (current_secondary_frame != nullptr && current_secondary_frame->uploaded_ui_thread != nullptr) {
475                 glWaitSync(current_secondary_frame->uploaded_ui_thread.get(), /*flags=*/0, GL_TIMEOUT_IGNORED);
476                 current_secondary_frame->uploaded_ui_thread.reset();
477         }
478
479         check_error();
480         current_chain->render_to_screen();
481
482         if (overlay_image != nullptr) {
483                 if (overlay_input_needs_refresh) {
484                         overlay_input->set_width(overlay_width);
485                         overlay_input->set_height(overlay_height);
486                         overlay_input->set_pixel_data(overlay_image->bits());
487                         overlay_input_needs_refresh = false;
488                 }
489                 glViewport(gl_width - overlay_width, 0, overlay_width, overlay_height);
490                 overlay_chain->render_to_screen();
491         }
492 }
493
494 namespace {
495
496 }  // namespace
497
498 void JPEGFrameView::setDecodedFrame(shared_ptr<Frame> frame, shared_ptr<Frame> secondary_frame, float fade_alpha)
499 {
500         post_to_main_thread([this, frame, secondary_frame, fade_alpha] {
501                 current_frame = frame;
502                 current_secondary_frame = secondary_frame;
503
504                 if (secondary_frame != nullptr) {
505                         current_chain = ycbcr_converter->prepare_chain_for_fade(frame, secondary_frame, fade_alpha);
506                 } else {
507                         current_chain = ycbcr_converter->prepare_chain_for_conversion(frame);
508                 }
509                 ++metric_jpeg_prepared_frames;
510                 displayed_this_frame = false;
511                 update();
512         });
513 }
514
515 void JPEGFrameView::mousePressEvent(QMouseEvent *event)
516 {
517         if (event->type() == QEvent::MouseButtonPress && event->button() == Qt::LeftButton) {
518                 emit clicked();
519         }
520 }
521
522 void JPEGFrameView::set_overlay(const string &text)
523 {
524         if (text.empty()) {
525                 overlay_image.reset();
526                 return;
527         }
528
529         // Figure out how large the texture needs to be.
530         {
531                 QImage img(overlay_width, overlay_height, QImage::Format_Grayscale8);
532                 QPainter painter(&img);
533                 QFont font = painter.font();
534                 font.setPointSize(12);
535                 QFontMetrics metrics(font);
536                 overlay_base_width = lrint(metrics.boundingRect(QString::fromStdString(text)).width() + 8.0);
537                 overlay_base_height = lrint(metrics.height());
538         }
539
540         float dpr = QGuiApplication::primaryScreen()->devicePixelRatio();
541         overlay_width = lrint(overlay_base_width * dpr);
542         overlay_height = lrint(overlay_base_height * dpr);
543
544         // Work around OpenGL alignment issues.
545         while (overlay_width % 4 != 0) ++overlay_width;
546
547         // Now do the actual drawing.
548         overlay_image.reset(new QImage(overlay_width, overlay_height, QImage::Format_Grayscale8));
549         overlay_image->setDevicePixelRatio(dpr);
550         overlay_image->fill(0);
551         QPainter painter(overlay_image.get());
552
553         painter.setPen(Qt::white);
554         QFont font = painter.font();
555         font.setPointSize(12);
556         painter.setFont(font);
557
558         painter.drawText(QRectF(0, 0, overlay_base_width, overlay_base_height), Qt::AlignCenter, QString::fromStdString(text));
559
560         // Don't refresh immediately; we might not have an OpenGL context here.
561         overlay_input_needs_refresh = true;
562 }
563
564 shared_ptr<Frame> get_black_frame()
565 {
566         static shared_ptr<Frame> black_frame;
567         static once_flag flag;
568         call_once(flag, [] {
569                 // Not really black, but whatever. :-)
570                 uint8_t black[] = { 0, 0, 0, 255 };
571                 RefCountedTexture black_tex = create_texture_2d(1, 1, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE, black);
572
573                 black_frame->y = black_tex;
574                 black_frame->cb = black_tex;
575                 black_frame->cr = move(black_tex);
576                 black_frame->width = 1;
577                 black_frame->height = 1;
578                 black_frame->chroma_subsampling_x = 1;
579                 black_frame->chroma_subsampling_y = 1;
580         });
581         ++metric_jpeg_software_fail_frames;
582         return black_frame;
583 }