]> git.sesse.net Git - nageru/blob - mixer.cpp
Add an option to scan through all possible modes for the PCI cards, as a substitute...
[nageru] / mixer.cpp
1 #undef Success
2
3 #include "mixer.h"
4
5 #include <assert.h>
6 #include <epoxy/egl.h>
7 #include <movit/effect_chain.h>
8 #include <movit/effect_util.h>
9 #include <movit/flat_input.h>
10 #include <movit/image_format.h>
11 #include <movit/init.h>
12 #include <movit/resource_pool.h>
13 #include <movit/util.h>
14 #include <stdint.h>
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <sys/time.h>
18 #include <time.h>
19 #include <algorithm>
20 #include <cmath>
21 #include <condition_variable>
22 #include <cstddef>
23 #include <memory>
24 #include <mutex>
25 #include <string>
26 #include <thread>
27 #include <utility>
28 #include <vector>
29 #include <arpa/inet.h>
30
31 #include "bmusb/bmusb.h"
32 #include "context.h"
33 #include "decklink_capture.h"
34 #include "defs.h"
35 #include "flags.h"
36 #include "h264encode.h"
37 #include "pbo_frame_allocator.h"
38 #include "ref_counted_gl_sync.h"
39 #include "timebase.h"
40
41 class QOpenGLContext;
42
43 using namespace movit;
44 using namespace std;
45 using namespace std::placeholders;
46
47 Mixer *global_mixer = nullptr;
48
49 namespace {
50
51 void convert_fixed24_to_fp32(float *dst, size_t out_channels, const uint8_t *src, size_t in_channels, size_t num_samples)
52 {
53         assert(in_channels >= out_channels);
54         for (size_t i = 0; i < num_samples; ++i) {
55                 for (size_t j = 0; j < out_channels; ++j) {
56                         uint32_t s1 = *src++;
57                         uint32_t s2 = *src++;
58                         uint32_t s3 = *src++;
59                         uint32_t s = s1 | (s1 << 8) | (s2 << 16) | (s3 << 24);
60                         dst[i * out_channels + j] = int(s) * (1.0f / 4294967296.0f);
61                 }
62                 src += 3 * (in_channels - out_channels);
63         }
64 }
65
66 void convert_fixed32_to_fp32(float *dst, size_t out_channels, const uint8_t *src, size_t in_channels, size_t num_samples)
67 {
68         assert(in_channels >= out_channels);
69         for (size_t i = 0; i < num_samples; ++i) {
70                 for (size_t j = 0; j < out_channels; ++j) {
71                         // Note: Assumes little-endian.
72                         int32_t s = *(int32_t *)src;
73                         dst[i * out_channels + j] = s * (1.0f / 4294967296.0f);
74                         src += 4;
75                 }
76                 src += 4 * (in_channels - out_channels);
77         }
78 }
79
80 void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced, unsigned card_index, InputState *input_state)
81 {
82         if (interlaced) {
83                 for (unsigned frame_num = FRAME_HISTORY_LENGTH; frame_num --> 1; ) {  // :-)
84                         input_state->buffered_frames[card_index][frame_num] =
85                                 input_state->buffered_frames[card_index][frame_num - 1];
86                 }
87                 input_state->buffered_frames[card_index][0] = { frame, field_num };
88         } else {
89                 for (unsigned frame_num = 0; frame_num < FRAME_HISTORY_LENGTH; ++frame_num) {
90                         input_state->buffered_frames[card_index][frame_num] = { frame, field_num };
91                 }
92         }
93 }
94
95 string generate_local_dump_filename(int frame)
96 {
97         time_t now = time(NULL);
98         tm now_tm;
99         localtime_r(&now, &now_tm);
100
101         char timestamp[256];
102         strftime(timestamp, sizeof(timestamp), "%F-%T%z", &now_tm);
103
104         // Use the frame number to disambiguate between two cuts starting
105         // on the same second.
106         char filename[256];
107         snprintf(filename, sizeof(filename), "%s%s-f%02d%s",
108                 LOCAL_DUMP_PREFIX, timestamp, frame % 100, LOCAL_DUMP_SUFFIX);
109         return filename;
110 }
111
112 }  // namespace
113
114 Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
115         : httpd(WIDTH, HEIGHT),
116           num_cards(num_cards),
117           mixer_surface(create_surface(format)),
118           h264_encoder_surface(create_surface(format)),
119           correlation(OUTPUT_FREQUENCY),
120           level_compressor(OUTPUT_FREQUENCY),
121           limiter(OUTPUT_FREQUENCY),
122           compressor(OUTPUT_FREQUENCY)
123 {
124         httpd.open_output_file(generate_local_dump_filename(/*frame=*/0).c_str());
125         httpd.start(9095);
126
127         CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
128         check_error();
129
130         // Since we allow non-bouncing 4:2:2 YCbCrInputs, effective subpixel precision
131         // will be halved when sampling them, and we need to compensate here.
132         movit_texel_subpixel_precision /= 2.0;
133
134         resource_pool.reset(new ResourcePool);
135         theme.reset(new Theme("theme.lua", resource_pool.get(), num_cards));
136         for (unsigned i = 0; i < NUM_OUTPUTS; ++i) {
137                 output_channel[i].parent = this;
138         }
139
140         ImageFormat inout_format;
141         inout_format.color_space = COLORSPACE_sRGB;
142         inout_format.gamma_curve = GAMMA_sRGB;
143
144         // Display chain; shows the live output produced by the main chain (its RGBA version).
145         display_chain.reset(new EffectChain(WIDTH, HEIGHT, resource_pool.get()));
146         check_error();
147         display_input = new FlatInput(inout_format, FORMAT_RGB, GL_UNSIGNED_BYTE, WIDTH, HEIGHT);  // FIXME: GL_UNSIGNED_BYTE is really wrong.
148         display_chain->add_input(display_input);
149         display_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
150         display_chain->set_dither_bits(0);  // Don't bother.
151         display_chain->finalize();
152
153         h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
154
155         // First try initializing the PCI devices, then USB, until we have the desired number of cards.
156         unsigned num_pci_devices = 0, num_usb_devices = 0;
157         unsigned card_index = 0;
158
159         IDeckLinkIterator *decklink_iterator = CreateDeckLinkIteratorInstance();
160         if (decklink_iterator != nullptr) {
161                 for ( ; card_index < num_cards; ++card_index) {
162                         IDeckLink *decklink;
163                         if (decklink_iterator->Next(&decklink) != S_OK) {
164                                 break;
165                         }
166
167                         configure_card(card_index, format, new DeckLinkCapture(decklink, card_index));
168                         ++num_pci_devices;
169                 }
170                 decklink_iterator->Release();
171                 fprintf(stderr, "Found %d DeckLink PCI card(s).\n", num_pci_devices);
172         } else {
173                 fprintf(stderr, "DeckLink drivers not found. Probing for USB cards only.\n");
174         }
175         for ( ; card_index < num_cards; ++card_index) {
176                 configure_card(card_index, format, new BMUSBCapture(card_index - num_pci_devices));
177                 ++num_usb_devices;
178         }
179
180         if (num_usb_devices > 0) {
181                 BMUSBCapture::start_bm_thread();
182         }
183
184         for (card_index = 0; card_index < num_cards; ++card_index) {
185                 cards[card_index].capture->start_bm_capture();
186         }
187
188         // Set up stuff for NV12 conversion.
189
190         // Cb/Cr shader.
191         string cbcr_vert_shader =
192                 "#version 130 \n"
193                 " \n"
194                 "in vec2 position; \n"
195                 "in vec2 texcoord; \n"
196                 "out vec2 tc0; \n"
197                 "uniform vec2 foo_chroma_offset_0; \n"
198                 " \n"
199                 "void main() \n"
200                 "{ \n"
201                 "    // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is: \n"
202                 "    // \n"
203                 "    //   2.000  0.000  0.000 -1.000 \n"
204                 "    //   0.000  2.000  0.000 -1.000 \n"
205                 "    //   0.000  0.000 -2.000 -1.000 \n"
206                 "    //   0.000  0.000  0.000  1.000 \n"
207                 "    gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0); \n"
208                 "    vec2 flipped_tc = texcoord; \n"
209                 "    tc0 = flipped_tc + foo_chroma_offset_0; \n"
210                 "} \n";
211         string cbcr_frag_shader =
212                 "#version 130 \n"
213                 "in vec2 tc0; \n"
214                 "uniform sampler2D cbcr_tex; \n"
215                 "out vec4 FragColor; \n"
216                 "void main() { \n"
217                 "    FragColor = texture(cbcr_tex, tc0); \n"
218                 "} \n";
219         vector<string> frag_shader_outputs;
220         cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader, frag_shader_outputs);
221
222         float vertices[] = {
223                 0.0f, 2.0f,
224                 0.0f, 0.0f,
225                 2.0f, 0.0f
226         };
227         cbcr_vbo = generate_vbo(2, GL_FLOAT, sizeof(vertices), vertices);
228         cbcr_position_attribute_index = glGetAttribLocation(cbcr_program_num, "position");
229         cbcr_texcoord_attribute_index = glGetAttribLocation(cbcr_program_num, "texcoord");
230
231         r128.init(2, OUTPUT_FREQUENCY);
232         r128.integr_start();
233
234         locut.init(FILTER_HPF, 2);
235
236         // hlen=16 is pretty low quality, but we use quite a bit of CPU otherwise,
237         // and there's a limit to how important the peak meter is.
238         peak_resampler.setup(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY * 4, /*num_channels=*/2, /*hlen=*/16, /*frel=*/1.0);
239
240         alsa.reset(new ALSAOutput(OUTPUT_FREQUENCY, /*num_channels=*/2));
241 }
242
243 Mixer::~Mixer()
244 {
245         resource_pool->release_glsl_program(cbcr_program_num);
246         glDeleteBuffers(1, &cbcr_vbo);
247         BMUSBCapture::stop_bm_thread();
248
249         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
250                 {
251                         unique_lock<mutex> lock(bmusb_mutex);
252                         cards[card_index].should_quit = true;  // Unblock thread.
253                         cards[card_index].new_data_ready_changed.notify_all();
254                 }
255                 cards[card_index].capture->stop_dequeue_thread();
256         }
257
258         h264_encoder.reset(nullptr);
259 }
260
261 void Mixer::configure_card(unsigned card_index, const QSurfaceFormat &format, CaptureInterface *capture)
262 {
263         printf("Configuring card %d...\n", card_index);
264
265         CaptureCard *card = &cards[card_index];
266         card->capture = capture;
267         card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
268         card->frame_allocator.reset(new PBOFrameAllocator(8 << 20, WIDTH, HEIGHT));  // 8 MB.
269         card->capture->set_video_frame_allocator(card->frame_allocator.get());
270         card->surface = create_surface(format);
271         card->capture->set_dequeue_thread_callbacks(
272                 [card]{
273                         eglBindAPI(EGL_OPENGL_API);
274                         card->context = create_context(card->surface);
275                         if (!make_current(card->context, card->surface)) {
276                                 printf("failed to create bmusb context\n");
277                                 exit(1);
278                         }
279                 },
280                 [this]{
281                         resource_pool->clean_context();
282                 });
283         card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
284         card->capture->configure_card();
285 }
286
287
288 namespace {
289
290 int unwrap_timecode(uint16_t current_wrapped, int last)
291 {
292         uint16_t last_wrapped = last & 0xffff;
293         if (current_wrapped > last_wrapped) {
294                 return (last & ~0xffff) | current_wrapped;
295         } else {
296                 return 0x10000 + ((last & ~0xffff) | current_wrapped);
297         }
298 }
299
300 float find_peak(const float *samples, size_t num_samples)
301 {
302         float m = fabs(samples[0]);
303         for (size_t i = 1; i < num_samples; ++i) {
304                 m = max(m, fabs(samples[i]));
305         }
306         return m;
307 }
308
309 void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<float> *out_r)
310 {
311         size_t num_samples = in.size() / 2;
312         out_l->resize(num_samples);
313         out_r->resize(num_samples);
314
315         const float *inptr = in.data();
316         float *lptr = &(*out_l)[0];
317         float *rptr = &(*out_r)[0];
318         for (size_t i = 0; i < num_samples; ++i) {
319                 *lptr++ = *inptr++;
320                 *rptr++ = *inptr++;
321         }
322 }
323
324 }  // namespace
325
326 void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
327                      FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
328                      FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
329 {
330         CaptureCard *card = &cards[card_index];
331
332         if (is_mode_scanning[card_index]) {
333                 if (video_format.has_signal) {
334                         // Found a stable signal, so stop scanning.
335                         is_mode_scanning[card_index] = false;
336                 } else {
337                         static constexpr double switch_time_s = 0.5;  // Should be enough time for the signal to stabilize.
338                         timespec now;
339                         clock_gettime(CLOCK_MONOTONIC, &now);
340                         double sec_since_last_switch = (now.tv_sec - last_mode_scan_change[card_index].tv_sec) +
341                                 1e-9 * (now.tv_nsec - last_mode_scan_change[card_index].tv_nsec);
342                         if (sec_since_last_switch > switch_time_s) {
343                                 // It isn't this mode; try the next one.
344                                 mode_scanlist_index[card_index]++;
345                                 mode_scanlist_index[card_index] %= mode_scanlist[card_index].size();
346                                 cards[card_index].capture->set_video_mode(mode_scanlist[card_index][mode_scanlist_index[card_index]]);
347                                 last_mode_scan_change[card_index] = now;
348                         }
349                 }
350         }
351
352         int64_t frame_length = int64_t(TIMEBASE * video_format.frame_rate_den) / video_format.frame_rate_nom;
353
354         size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / audio_format.num_channels / (audio_format.bits_per_sample / 8) : 0;
355         if (num_samples > OUTPUT_FREQUENCY / 10) {
356                 printf("Card %d: Dropping frame with implausible audio length (len=%d, offset=%d) [timecode=0x%04x video_len=%d video_offset=%d video_format=%x)\n",
357                         card_index, int(audio_frame.len), int(audio_offset),
358                         timecode, int(video_frame.len), int(video_offset), video_format.id);
359                 if (video_frame.owner) {
360                         video_frame.owner->release_frame(video_frame);
361                 }
362                 if (audio_frame.owner) {
363                         audio_frame.owner->release_frame(audio_frame);
364                 }
365                 return;
366         }
367
368         int64_t local_pts = card->next_local_pts;
369         int dropped_frames = 0;
370         if (card->last_timecode != -1) {
371                 dropped_frames = unwrap_timecode(timecode, card->last_timecode) - card->last_timecode - 1;
372         }
373
374         // Convert the audio to stereo fp32 and add it.
375         vector<float> audio;
376         audio.resize(num_samples * 2);
377         switch (audio_format.bits_per_sample) {
378         case 24:
379                 convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
380                 break;
381         case 32:
382                 convert_fixed32_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
383                 break;
384         default:
385                 fprintf(stderr, "Cannot handle audio with %u bits per sample\n", audio_format.bits_per_sample);
386                 assert(false);
387         }
388
389         // Add the audio.
390         {
391                 unique_lock<mutex> lock(card->audio_mutex);
392
393                 // Number of samples per frame if we need to insert silence.
394                 // (Could be nonintegral, but resampling will save us then.)
395                 int silence_samples = OUTPUT_FREQUENCY * video_format.frame_rate_den / video_format.frame_rate_nom;
396
397                 if (dropped_frames > MAX_FPS * 2) {
398                         fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
399                                 card_index, card->last_timecode, timecode);
400                         card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
401                         dropped_frames = 0;
402                 } else if (dropped_frames > 0) {
403                         // Insert silence as needed.
404                         fprintf(stderr, "Card %d dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
405                                 card_index, dropped_frames, timecode);
406                         vector<float> silence(silence_samples * 2, 0.0f);
407                         for (int i = 0; i < dropped_frames; ++i) {
408                                 card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), silence.data(), silence_samples);
409                                 // Note that if the format changed in the meantime, we have
410                                 // no way of detecting that; we just have to assume the frame length
411                                 // is always the same.
412                                 local_pts += frame_length;
413                         }
414                 }
415                 if (num_samples == 0) {
416                         audio.resize(silence_samples * 2);
417                         num_samples = silence_samples;
418                 }
419                 card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), audio.data(), num_samples);
420                 card->next_local_pts = local_pts + frame_length;
421         }
422
423         card->last_timecode = timecode;
424
425         // Done with the audio, so release it.
426         if (audio_frame.owner) {
427                 audio_frame.owner->release_frame(audio_frame);
428         }
429
430         {
431                 // Wait until the previous frame was consumed.
432                 unique_lock<mutex> lock(bmusb_mutex);
433                 card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready || card->should_quit; });
434                 if (card->should_quit) return;
435         }
436
437         size_t expected_length = video_format.width * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom) * 2;
438         if (video_frame.len - video_offset == 0 ||
439             video_frame.len - video_offset != expected_length) {
440                 if (video_frame.len != 0) {
441                         printf("Card %d: Dropping video frame with wrong length (%ld; expected %ld)\n",
442                                 card_index, video_frame.len - video_offset, expected_length);
443                 }
444                 if (video_frame.owner) {
445                         video_frame.owner->release_frame(video_frame);
446                 }
447
448                 // Still send on the information that we _had_ a frame, even though it's corrupted,
449                 // so that pts can go up accordingly.
450                 {
451                         unique_lock<mutex> lock(bmusb_mutex);
452                         card->new_data_ready = true;
453                         card->new_frame = RefCountedFrame(FrameAllocator::Frame());
454                         card->new_frame_length = frame_length;
455                         card->new_frame_interlaced = false;
456                         card->new_data_ready_fence = nullptr;
457                         card->dropped_frames = dropped_frames;
458                         card->new_data_ready_changed.notify_all();
459                 }
460                 return;
461         }
462
463         PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
464
465         unsigned num_fields = video_format.interlaced ? 2 : 1;
466         timespec frame_upload_start;
467         if (video_format.interlaced) {
468                 // Send the two fields along as separate frames; the other side will need to add
469                 // a deinterlacer to actually get this right.
470                 assert(video_format.height % 2 == 0);
471                 video_format.height /= 2;
472                 assert(frame_length % 2 == 0);
473                 frame_length /= 2;
474                 num_fields = 2;
475                 clock_gettime(CLOCK_MONOTONIC, &frame_upload_start);
476         }
477         userdata->last_interlaced = video_format.interlaced;
478         userdata->last_has_signal = video_format.has_signal;
479         userdata->last_frame_rate_nom = video_format.frame_rate_nom;
480         userdata->last_frame_rate_den = video_format.frame_rate_den;
481         RefCountedFrame new_frame(video_frame);
482
483         // Upload the textures.
484         size_t cbcr_width = video_format.width / 2;
485         size_t cbcr_offset = video_offset / 2;
486         size_t y_offset = video_frame.size / 2 + video_offset / 2;
487
488         for (unsigned field = 0; field < num_fields; ++field) {
489                 unsigned field_start_line = (field == 1) ? video_format.second_field_start : video_format.extra_lines_top + field * (video_format.height + 22);
490
491                 if (userdata->tex_y[field] == 0 ||
492                     userdata->tex_cbcr[field] == 0 ||
493                     video_format.width != userdata->last_width[field] ||
494                     video_format.height != userdata->last_height[field]) {
495                         // We changed resolution since last use of this texture, so we need to create
496                         // a new object. Note that this each card has its own PBOFrameAllocator,
497                         // we don't need to worry about these flip-flopping between resolutions.
498                         glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
499                         check_error();
500                         glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, video_format.height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
501                         check_error();
502                         glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
503                         check_error();
504                         glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, video_format.width, video_format.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
505                         check_error();
506                         userdata->last_width[field] = video_format.width;
507                         userdata->last_height[field] = video_format.height;
508                 }
509
510                 GLuint pbo = userdata->pbo;
511                 check_error();
512                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
513                 check_error();
514                 glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
515                 check_error();
516
517                 glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
518                 check_error();
519                 glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, video_format.height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t)));
520                 check_error();
521                 glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
522                 check_error();
523                 glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, video_format.width, video_format.height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(y_offset + video_format.width * field_start_line));
524                 check_error();
525                 glBindTexture(GL_TEXTURE_2D, 0);
526                 check_error();
527                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
528                 check_error();
529                 GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
530                 check_error();
531                 assert(fence != nullptr);
532
533                 if (field == 1) {
534                         // Don't upload the second field as fast as we can; wait until
535                         // the field time has approximately passed. (Otherwise, we could
536                         // get timing jitter against the other sources, and possibly also
537                         // against the video display, although the latter is not as critical.)
538                         // This requires our system clock to be reasonably close to the
539                         // video clock, but that's not an unreasonable assumption.
540                         timespec second_field_start;
541                         second_field_start.tv_nsec = frame_upload_start.tv_nsec +
542                                 frame_length * 1000000000 / TIMEBASE;
543                         second_field_start.tv_sec = frame_upload_start.tv_sec +
544                                 second_field_start.tv_nsec / 1000000000;
545                         second_field_start.tv_nsec %= 1000000000;
546
547                         while (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
548                                                &second_field_start, nullptr) == -1 &&
549                                errno == EINTR) ;
550                 }
551
552                 {
553                         unique_lock<mutex> lock(bmusb_mutex);
554                         card->new_data_ready = true;
555                         card->new_frame = new_frame;
556                         card->new_frame_length = frame_length;
557                         card->new_frame_field = field;
558                         card->new_frame_interlaced = video_format.interlaced;
559                         card->new_data_ready_fence = fence;
560                         card->dropped_frames = dropped_frames;
561                         card->new_data_ready_changed.notify_all();
562
563                         if (field != num_fields - 1) {
564                                 // Wait until the previous frame was consumed.
565                                 card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready || card->should_quit; });
566                                 if (card->should_quit) return;
567                         }
568                 }
569         }
570 }
571
572 void Mixer::thread_func()
573 {
574         eglBindAPI(EGL_OPENGL_API);
575         QOpenGLContext *context = create_context(mixer_surface);
576         if (!make_current(context, mixer_surface)) {
577                 printf("oops\n");
578                 exit(1);
579         }
580
581         struct timespec start, now;
582         clock_gettime(CLOCK_MONOTONIC, &start);
583
584         int frame = 0;
585         int stats_dropped_frames = 0;
586
587         while (!should_quit) {
588                 CaptureCard card_copy[MAX_CARDS];
589                 int num_samples[MAX_CARDS];
590
591                 {
592                         unique_lock<mutex> lock(bmusb_mutex);
593
594                         // The first card is the master timer, so wait for it to have a new frame.
595                         // TODO: Make configurable, and with a timeout.
596                         cards[0].new_data_ready_changed.wait(lock, [this]{ return cards[0].new_data_ready; });
597
598                         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
599                                 CaptureCard *card = &cards[card_index];
600                                 card_copy[card_index].new_data_ready = card->new_data_ready;
601                                 card_copy[card_index].new_frame = card->new_frame;
602                                 card_copy[card_index].new_frame_length = card->new_frame_length;
603                                 card_copy[card_index].new_frame_field = card->new_frame_field;
604                                 card_copy[card_index].new_frame_interlaced = card->new_frame_interlaced;
605                                 card_copy[card_index].new_data_ready_fence = card->new_data_ready_fence;
606                                 card_copy[card_index].dropped_frames = card->dropped_frames;
607                                 card->new_data_ready = false;
608                                 card->new_data_ready_changed.notify_all();
609
610                                 int num_samples_times_timebase = OUTPUT_FREQUENCY * card->new_frame_length + card->fractional_samples;
611                                 num_samples[card_index] = num_samples_times_timebase / TIMEBASE;
612                                 card->fractional_samples = num_samples_times_timebase % TIMEBASE;
613                                 assert(num_samples[card_index] >= 0);
614                         }
615                 }
616
617                 // Resample the audio as needed, including from previously dropped frames.
618                 assert(num_cards > 0);
619                 for (unsigned frame_num = 0; frame_num < card_copy[0].dropped_frames + 1; ++frame_num) {
620                         {
621                                 // Signal to the audio thread to process this frame.
622                                 unique_lock<mutex> lock(audio_mutex);
623                                 audio_task_queue.push(AudioTask{pts_int, num_samples[0]});
624                                 audio_task_queue_changed.notify_one();
625                         }
626                         if (frame_num != card_copy[0].dropped_frames) {
627                                 // For dropped frames, increase the pts. Note that if the format changed
628                                 // in the meantime, we have no way of detecting that; we just have to
629                                 // assume the frame length is always the same.
630                                 ++stats_dropped_frames;
631                                 pts_int += card_copy[0].new_frame_length;
632                         }
633                 }
634
635                 if (audio_level_callback != nullptr) {
636                         unique_lock<mutex> lock(compressor_mutex);
637                         double loudness_s = r128.loudness_S();
638                         double loudness_i = r128.integrated();
639                         double loudness_range_low = r128.range_min();
640                         double loudness_range_high = r128.range_max();
641
642                         audio_level_callback(loudness_s, 20.0 * log10(peak),
643                                              loudness_i, loudness_range_low, loudness_range_high,
644                                              gain_staging_db, 20.0 * log10(final_makeup_gain),
645                                              correlation.get_correlation());
646                 }
647
648                 for (unsigned card_index = 1; card_index < num_cards; ++card_index) {
649                         if (card_copy[card_index].new_data_ready && card_copy[card_index].new_frame->len == 0) {
650                                 ++card_copy[card_index].dropped_frames;
651                         }
652                         if (card_copy[card_index].dropped_frames > 0) {
653                                 printf("Card %u dropped %d frames before this\n",
654                                         card_index, int(card_copy[card_index].dropped_frames));
655                         }
656                 }
657
658                 // If the first card is reporting a corrupted or otherwise dropped frame,
659                 // just increase the pts (skipping over this frame) and don't try to compute anything new.
660                 if (card_copy[0].new_frame->len == 0) {
661                         ++stats_dropped_frames;
662                         pts_int += card_copy[0].new_frame_length;
663                         continue;
664                 }
665
666                 for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
667                         CaptureCard *card = &card_copy[card_index];
668                         if (!card->new_data_ready || card->new_frame->len == 0)
669                                 continue;
670
671                         assert(card->new_frame != nullptr);
672                         insert_new_frame(card->new_frame, card->new_frame_field, card->new_frame_interlaced, card_index, &input_state);
673                         check_error();
674
675                         // The new texture might still be uploaded,
676                         // tell the GPU to wait until it's there.
677                         if (card->new_data_ready_fence) {
678                                 glWaitSync(card->new_data_ready_fence, /*flags=*/0, GL_TIMEOUT_IGNORED);
679                                 check_error();
680                                 glDeleteSync(card->new_data_ready_fence);
681                                 check_error();
682                         }
683                 }
684
685                 // Get the main chain from the theme, and set its state immediately.
686                 Theme::Chain theme_main_chain = theme->get_chain(0, pts(), WIDTH, HEIGHT, input_state);
687                 EffectChain *chain = theme_main_chain.chain;
688                 theme_main_chain.setup_chain();
689                 //theme_main_chain.chain->enable_phase_timing(true);
690
691                 GLuint y_tex, cbcr_tex;
692                 bool got_frame = h264_encoder->begin_frame(&y_tex, &cbcr_tex);
693                 assert(got_frame);
694
695                 // Render main chain.
696                 GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
697                 GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, WIDTH, HEIGHT);  // Saves texture bandwidth, although dithering gets messed up.
698                 GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
699                 check_error();
700                 chain->render_to_fbo(fbo, WIDTH, HEIGHT);
701                 resource_pool->release_fbo(fbo);
702
703                 subsample_chroma(cbcr_full_tex, cbcr_tex);
704                 resource_pool->release_2d_texture(cbcr_full_tex);
705
706                 // Set the right state for rgba_tex.
707                 glBindFramebuffer(GL_FRAMEBUFFER, 0);
708                 glBindTexture(GL_TEXTURE_2D, rgba_tex);
709                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
710                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
711                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
712
713                 RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
714                 check_error();
715
716                 const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampling_queue.h. TODO: Make less hard-coded.
717                 h264_encoder->end_frame(fence, pts_int + av_delay, theme_main_chain.input_frames);
718                 ++frame;
719                 pts_int += card_copy[0].new_frame_length;
720
721                 // The live frame just shows the RGBA texture we just rendered.
722                 // It owns rgba_tex now.
723                 DisplayFrame live_frame;
724                 live_frame.chain = display_chain.get();
725                 live_frame.setup_chain = [this, rgba_tex]{
726                         display_input->set_texture_num(rgba_tex);
727                 };
728                 live_frame.ready_fence = fence;
729                 live_frame.input_frames = {};
730                 live_frame.temp_textures = { rgba_tex };
731                 output_channel[OUTPUT_LIVE].output_frame(live_frame);
732
733                 // Set up preview and any additional channels.
734                 for (int i = 1; i < theme->get_num_channels() + 2; ++i) {
735                         DisplayFrame display_frame;
736                         Theme::Chain chain = theme->get_chain(i, pts(), WIDTH, HEIGHT, input_state);  // FIXME: dimensions
737                         display_frame.chain = chain.chain;
738                         display_frame.setup_chain = chain.setup_chain;
739                         display_frame.ready_fence = fence;
740                         display_frame.input_frames = chain.input_frames;
741                         display_frame.temp_textures = {};
742                         output_channel[i].output_frame(display_frame);
743                 }
744
745                 clock_gettime(CLOCK_MONOTONIC, &now);
746                 double elapsed = now.tv_sec - start.tv_sec +
747                         1e-9 * (now.tv_nsec - start.tv_nsec);
748                 if (frame % 100 == 0) {
749                         printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
750                                 frame, stats_dropped_frames, elapsed, frame / elapsed,
751                                 1e3 * elapsed / frame);
752                 //      chain->print_phase_timing();
753                 }
754
755                 if (should_cut.exchange(false)) {  // Test and clear.
756                         string filename = generate_local_dump_filename(frame);
757                         printf("Starting new recording: %s\n", filename.c_str());
758                         h264_encoder->shutdown();
759                         httpd.close_output_file();
760                         httpd.open_output_file(filename.c_str());
761                         h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
762                 }
763
764 #if 0
765                 // Reset every 100 frames, so that local variations in frame times
766                 // (especially for the first few frames, when the shaders are
767                 // compiled etc.) don't make it hard to measure for the entire
768                 // remaining duration of the program.
769                 if (frame == 10000) {
770                         frame = 0;
771                         start = now;
772                 }
773 #endif
774                 check_error();
775         }
776
777         resource_pool->clean_context();
778 }
779
780 void Mixer::audio_thread_func()
781 {
782         while (!should_quit) {
783                 AudioTask task;
784
785                 {
786                         unique_lock<mutex> lock(audio_mutex);
787                         audio_task_queue_changed.wait(lock, [this]{ return !audio_task_queue.empty(); });
788                         task = audio_task_queue.front();
789                         audio_task_queue.pop();
790                 }
791
792                 process_audio_one_frame(task.pts_int, task.num_samples);
793         }
794 }
795
796 void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
797 {
798         vector<float> samples_card;
799         vector<float> samples_out;
800
801         // TODO: Allow mixing audio from several sources.
802         unsigned selected_audio_card = theme->map_signal(audio_source_channel);
803         assert(selected_audio_card < num_cards);
804
805         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
806                 samples_card.resize(num_samples * 2);
807                 {
808                         unique_lock<mutex> lock(cards[card_index].audio_mutex);
809                         if (!cards[card_index].resampling_queue->get_output_samples(double(frame_pts_int) / TIMEBASE, &samples_card[0], num_samples)) {
810                                 printf("Card %d reported previous underrun.\n", card_index);
811                         }
812                 }
813                 if (card_index == selected_audio_card) {
814                         samples_out = move(samples_card);
815                 }
816         }
817
818         // Cut away everything under 120 Hz (or whatever the cutoff is);
819         // we don't need it for voice, and it will reduce headroom
820         // and confuse the compressor. (In particular, any hums at 50 or 60 Hz
821         // should be dampened.)
822         if (locut_enabled) {
823                 locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
824         }
825
826         // Apply a level compressor to get the general level right.
827         // Basically, if it's over about -40 dBFS, we squeeze it down to that level
828         // (or more precisely, near it, since we don't use infinite ratio),
829         // then apply a makeup gain to get it to -14 dBFS. -14 dBFS is, of course,
830         // entirely arbitrary, but from practical tests with speech, it seems to
831         // put ut around -23 LUFS, so it's a reasonable starting point for later use.
832         {
833                 unique_lock<mutex> lock(compressor_mutex);
834                 if (level_compressor_enabled) {
835                         float threshold = 0.01f;   // -40 dBFS.
836                         float ratio = 20.0f;
837                         float attack_time = 0.5f;
838                         float release_time = 20.0f;
839                         float makeup_gain = pow(10.0f, (ref_level_dbfs - (-40.0f)) / 20.0f);  // +26 dB.
840                         level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
841                         gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
842                 } else {
843                         // Just apply the gain we already had.
844                         float g = pow(10.0f, gain_staging_db / 20.0f);
845                         for (size_t i = 0; i < samples_out.size(); ++i) {
846                                 samples_out[i] *= g;
847                         }
848                 }
849         }
850
851 #if 0
852         printf("level=%f (%+5.2f dBFS) attenuation=%f (%+5.2f dB) end_result=%+5.2f dB\n",
853                 level_compressor.get_level(), 20.0 * log10(level_compressor.get_level()),
854                 level_compressor.get_attenuation(), 20.0 * log10(level_compressor.get_attenuation()),
855                 20.0 * log10(level_compressor.get_level() * level_compressor.get_attenuation() * makeup_gain));
856 #endif
857
858 //      float limiter_att, compressor_att;
859
860         // The real compressor.
861         if (compressor_enabled) {
862                 float threshold = pow(10.0f, compressor_threshold_dbfs / 20.0f);
863                 float ratio = 20.0f;
864                 float attack_time = 0.005f;
865                 float release_time = 0.040f;
866                 float makeup_gain = 2.0f;  // +6 dB.
867                 compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
868 //              compressor_att = compressor.get_attenuation();
869         }
870
871         // Finally a limiter at -4 dB (so, -10 dBFS) to take out the worst peaks only.
872         // Note that since ratio is not infinite, we could go slightly higher than this.
873         if (limiter_enabled) {
874                 float threshold = pow(10.0f, limiter_threshold_dbfs / 20.0f);
875                 float ratio = 30.0f;
876                 float attack_time = 0.0f;  // Instant.
877                 float release_time = 0.020f;
878                 float makeup_gain = 1.0f;  // 0 dB.
879                 limiter.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
880 //              limiter_att = limiter.get_attenuation();
881         }
882
883 //      printf("limiter=%+5.1f  compressor=%+5.1f\n", 20.0*log10(limiter_att), 20.0*log10(compressor_att));
884
885         // Upsample 4x to find interpolated peak.
886         peak_resampler.inp_data = samples_out.data();
887         peak_resampler.inp_count = samples_out.size() / 2;
888
889         vector<float> interpolated_samples_out;
890         interpolated_samples_out.resize(samples_out.size());
891         while (peak_resampler.inp_count > 0) {  // About four iterations.
892                 peak_resampler.out_data = &interpolated_samples_out[0];
893                 peak_resampler.out_count = interpolated_samples_out.size() / 2;
894                 peak_resampler.process();
895                 size_t out_stereo_samples = interpolated_samples_out.size() / 2 - peak_resampler.out_count;
896                 peak = max<float>(peak, find_peak(interpolated_samples_out.data(), out_stereo_samples * 2));
897                 peak_resampler.out_data = nullptr;
898         }
899
900         // At this point, we are most likely close to +0 LU, but all of our
901         // measurements have been on raw sample values, not R128 values.
902         // So we have a final makeup gain to get us to +0 LU; the gain
903         // adjustments required should be relatively small, and also, the
904         // offset shouldn't change much (only if the type of audio changes
905         // significantly). Thus, we shoot for updating this value basically
906         // “whenever we process buffers”, since the R128 calculation isn't exactly
907         // something we get out per-sample.
908         //
909         // Note that there's a feedback loop here, so we choose a very slow filter
910         // (half-time of 100 seconds).
911         double target_loudness_factor, alpha;
912         {
913                 unique_lock<mutex> lock(compressor_mutex);
914                 double loudness_lu = r128.loudness_M() - ref_level_lufs;
915                 double current_makeup_lu = 20.0f * log10(final_makeup_gain);
916                 target_loudness_factor = pow(10.0f, -loudness_lu / 20.0f);
917
918                 // If we're outside +/- 5 LU uncorrected, we don't count it as
919                 // a normal signal (probably silence) and don't change the
920                 // correction factor; just apply what we already have.
921                 if (fabs(loudness_lu - current_makeup_lu) >= 5.0 || !final_makeup_gain_auto) {
922                         alpha = 0.0;
923                 } else {
924                         // Formula adapted from
925                         // https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter.
926                         const double half_time_s = 100.0;
927                         const double fc_mul_2pi_delta_t = 1.0 / (half_time_s * OUTPUT_FREQUENCY);
928                         alpha = fc_mul_2pi_delta_t / (fc_mul_2pi_delta_t + 1.0);
929                 }
930
931                 double m = final_makeup_gain;
932                 for (size_t i = 0; i < samples_out.size(); i += 2) {
933                         samples_out[i + 0] *= m;
934                         samples_out[i + 1] *= m;
935                         m += (target_loudness_factor - m) * alpha;
936                 }
937                 final_makeup_gain = m;
938         }
939
940         // Find R128 levels and L/R correlation.
941         vector<float> left, right;
942         deinterleave_samples(samples_out, &left, &right);
943         float *ptrs[] = { left.data(), right.data() };
944         {
945                 unique_lock<mutex> lock(compressor_mutex);
946                 r128.process(left.size(), ptrs);
947                 correlation.process_samples(samples_out);
948         }
949
950         // Send the samples to the sound card.
951         if (alsa) {
952                 alsa->write(samples_out);
953         }
954
955         // And finally add them to the output.
956         h264_encoder->add_audio(frame_pts_int, move(samples_out));
957 }
958
959 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
960 {
961         GLuint vao;
962         glGenVertexArrays(1, &vao);
963         check_error();
964
965         glBindVertexArray(vao);
966         check_error();
967
968         // Extract Cb/Cr.
969         GLuint fbo = resource_pool->create_fbo(dst_tex);
970         glBindFramebuffer(GL_FRAMEBUFFER, fbo);
971         glViewport(0, 0, WIDTH/2, HEIGHT/2);
972         check_error();
973
974         glUseProgram(cbcr_program_num);
975         check_error();
976
977         glActiveTexture(GL_TEXTURE0);
978         check_error();
979         glBindTexture(GL_TEXTURE_2D, src_tex);
980         check_error();
981         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
982         check_error();
983         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
984         check_error();
985         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
986         check_error();
987
988         float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
989         set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
990
991         glBindBuffer(GL_ARRAY_BUFFER, cbcr_vbo);
992         check_error();
993
994         for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
995                 glEnableVertexAttribArray(attr_index);
996                 check_error();
997                 glVertexAttribPointer(attr_index, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
998                 check_error();
999         }
1000
1001         glDrawArrays(GL_TRIANGLES, 0, 3);
1002         check_error();
1003
1004         for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
1005                 glDisableVertexAttribArray(attr_index);
1006                 check_error();
1007         }
1008
1009         glUseProgram(0);
1010         check_error();
1011         glBindFramebuffer(GL_FRAMEBUFFER, 0);
1012         check_error();
1013
1014         resource_pool->release_fbo(fbo);
1015         glDeleteVertexArrays(1, &vao);
1016 }
1017
1018 void Mixer::release_display_frame(DisplayFrame *frame)
1019 {
1020         for (GLuint texnum : frame->temp_textures) {
1021                 resource_pool->release_2d_texture(texnum);
1022         }
1023         frame->temp_textures.clear();
1024         frame->ready_fence.reset();
1025         frame->input_frames.clear();
1026 }
1027
1028 void Mixer::start()
1029 {
1030         mixer_thread = thread(&Mixer::thread_func, this);
1031         audio_thread = thread(&Mixer::audio_thread_func, this);
1032 }
1033
1034 void Mixer::quit()
1035 {
1036         should_quit = true;
1037         mixer_thread.join();
1038         audio_thread.join();
1039 }
1040
1041 void Mixer::transition_clicked(int transition_num)
1042 {
1043         theme->transition_clicked(transition_num, pts());
1044 }
1045
1046 void Mixer::channel_clicked(int preview_num)
1047 {
1048         theme->channel_clicked(preview_num);
1049 }
1050
1051 void Mixer::reset_meters()
1052 {
1053         peak_resampler.reset();
1054         peak = 0.0f;
1055         r128.reset();
1056         r128.integr_start();
1057         correlation.reset();
1058 }
1059
1060 void Mixer::start_mode_scanning(unsigned card_index)
1061 {
1062         assert(card_index < num_cards);
1063         if (is_mode_scanning[card_index]) {
1064                 return;
1065         }
1066         is_mode_scanning[card_index] = true;
1067         mode_scanlist[card_index].clear();
1068         for (const auto &mode : cards[card_index].capture->get_available_video_modes()) {
1069                 mode_scanlist[card_index].push_back(mode.first);
1070         }
1071         assert(!mode_scanlist[card_index].empty());
1072         mode_scanlist_index[card_index] = 0;
1073         cards[card_index].capture->set_video_mode(mode_scanlist[card_index][0]);
1074         clock_gettime(CLOCK_MONOTONIC, &last_mode_scan_change[card_index]);
1075 }
1076
1077 Mixer::OutputChannel::~OutputChannel()
1078 {
1079         if (has_current_frame) {
1080                 parent->release_display_frame(&current_frame);
1081         }
1082         if (has_ready_frame) {
1083                 parent->release_display_frame(&ready_frame);
1084         }
1085 }
1086
1087 void Mixer::OutputChannel::output_frame(DisplayFrame frame)
1088 {
1089         // Store this frame for display. Remove the ready frame if any
1090         // (it was seemingly never used).
1091         {
1092                 unique_lock<mutex> lock(frame_mutex);
1093                 if (has_ready_frame) {
1094                         parent->release_display_frame(&ready_frame);
1095                 }
1096                 ready_frame = frame;
1097                 has_ready_frame = true;
1098         }
1099
1100         if (has_new_frame_ready_callback) {
1101                 new_frame_ready_callback();
1102         }
1103 }
1104
1105 bool Mixer::OutputChannel::get_display_frame(DisplayFrame *frame)
1106 {
1107         unique_lock<mutex> lock(frame_mutex);
1108         if (!has_current_frame && !has_ready_frame) {
1109                 return false;
1110         }
1111
1112         if (has_current_frame && has_ready_frame) {
1113                 // We have a new ready frame. Toss the current one.
1114                 parent->release_display_frame(&current_frame);
1115                 has_current_frame = false;
1116         }
1117         if (has_ready_frame) {
1118                 assert(!has_current_frame);
1119                 current_frame = ready_frame;
1120                 ready_frame.ready_fence.reset();  // Drop the refcount.
1121                 ready_frame.input_frames.clear();  // Drop the refcounts.
1122                 has_current_frame = true;
1123                 has_ready_frame = false;
1124         }
1125
1126         *frame = current_frame;
1127         return true;
1128 }
1129
1130 void Mixer::OutputChannel::set_frame_ready_callback(Mixer::new_frame_ready_callback_t callback)
1131 {
1132         new_frame_ready_callback = callback;
1133         has_new_frame_ready_callback = true;
1134 }