git.sesse.net Git - nageru/blob - 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_frames_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 0:
 379                 assert(num_samples == 0);
 380                 break;
 381         case 24:
 382                 convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
 383                 break;
 384         case 32:
 385                 convert_fixed32_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
 386                 break;
 387         default:
 388                 fprintf(stderr, "Cannot handle audio with %u bits per sample\n", audio_format.bits_per_sample);
 389                 assert(false);
 390         }
 391
 392         // Add the audio.
 393         {
 394                 unique_lock<mutex> lock(card->audio_mutex);
 395
 396                 // Number of samples per frame if we need to insert silence.
 397                 // (Could be nonintegral, but resampling will save us then.)
 398                 int silence_samples = OUTPUT_FREQUENCY * video_format.frame_rate_den / video_format.frame_rate_nom;
 399
 400                 if (dropped_frames > MAX_FPS * 2) {
 401                         fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
 402                                 card_index, card->last_timecode, timecode);
 403                         card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
 404                         dropped_frames = 0;
 405                 } else if (dropped_frames > 0) {
 406                         // Insert silence as needed.
 407                         fprintf(stderr, "Card %d dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
 408                                 card_index, dropped_frames, timecode);
 409                         vector<float> silence(silence_samples * 2, 0.0f);
 410                         for (int i = 0; i < dropped_frames; ++i) {
 411                                 card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), silence.data(), silence_samples);
 412                                 // Note that if the format changed in the meantime, we have
 413                                 // no way of detecting that; we just have to assume the frame length
 414                                 // is always the same.
 415                                 local_pts += frame_length;
 416                         }
 417                 }
 418                 if (num_samples == 0) {
 419                         audio.resize(silence_samples * 2);
 420                         num_samples = silence_samples;
 421                 }
 422                 card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), audio.data(), num_samples);
 423                 card->next_local_pts = local_pts + frame_length;
 424         }
 425
 426         card->last_timecode = timecode;
 427
 428         // Done with the audio, so release it.
 429         if (audio_frame.owner) {
 430                 audio_frame.owner->release_frame(audio_frame);
 431         }
 432
 433         size_t expected_length = video_format.width * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom) * 2;
 434         if (video_frame.len - video_offset == 0 ||
 435             video_frame.len - video_offset != expected_length) {
 436                 if (video_frame.len != 0) {
 437                         printf("Card %d: Dropping video frame with wrong length (%ld; expected %ld)\n",
 438                                 card_index, video_frame.len - video_offset, expected_length);
 439                 }
 440                 if (video_frame.owner) {
 441                         video_frame.owner->release_frame(video_frame);
 442                 }
 443
 444                 // Still send on the information that we _had_ a frame, even though it's corrupted,
 445                 // so that pts can go up accordingly.
 446                 {
 447                         unique_lock<mutex> lock(bmusb_mutex);
 448                         CaptureCard::NewFrame new_frame;
 449                         new_frame.frame = RefCountedFrame(FrameAllocator::Frame());
 450                         new_frame.length = frame_length;
 451                         new_frame.interlaced = false;
 452                         new_frame.ready_fence = nullptr;
 453                         new_frame.dropped_frames = dropped_frames;
 454                         card->new_frames.push(move(new_frame));
 455                         card->new_frames_changed.notify_all();
 456                 }
 457                 return;
 458         }
 459
 460         PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
 461
 462         unsigned num_fields = video_format.interlaced ? 2 : 1;
 463         timespec frame_upload_start;
 464         if (video_format.interlaced) {
 465                 // Send the two fields along as separate frames; the other side will need to add
 466                 // a deinterlacer to actually get this right.
 467                 assert(video_format.height % 2 == 0);
 468                 video_format.height /= 2;
 469                 assert(frame_length % 2 == 0);
 470                 frame_length /= 2;
 471                 num_fields = 2;
 472                 clock_gettime(CLOCK_MONOTONIC, &frame_upload_start);
 473         }
 474         userdata->last_interlaced = video_format.interlaced;
 475         userdata->last_has_signal = video_format.has_signal;
 476         userdata->last_frame_rate_nom = video_format.frame_rate_nom;
 477         userdata->last_frame_rate_den = video_format.frame_rate_den;
 478         RefCountedFrame frame(video_frame);
 479
 480         // Upload the textures.
 481         size_t cbcr_width = video_format.width / 2;
 482         size_t cbcr_offset = video_offset / 2;
 483         size_t y_offset = video_frame.size / 2 + video_offset / 2;
 484
 485         for (unsigned field = 0; field < num_fields; ++field) {
 486                 unsigned field_start_line = (field == 1) ? video_format.second_field_start : video_format.extra_lines_top + field * (video_format.height + 22);
 487
 488                 if (userdata->tex_y[field] == 0 ||
 489                     userdata->tex_cbcr[field] == 0 ||
 490                     video_format.width != userdata->last_width[field] ||
 491                     video_format.height != userdata->last_height[field]) {
 492                         // We changed resolution since last use of this texture, so we need to create
 493                         // a new object. Note that this each card has its own PBOFrameAllocator,
 494                         // we don't need to worry about these flip-flopping between resolutions.
 495                         glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
 496                         check_error();
 497                         glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, video_format.height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
 498                         check_error();
 499                         glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
 500                         check_error();
 501                         glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, video_format.width, video_format.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
 502                         check_error();
 503                         userdata->last_width[field] = video_format.width;
 504                         userdata->last_height[field] = video_format.height;
 505                 }
 506
 507                 GLuint pbo = userdata->pbo;
 508                 check_error();
 509                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
 510                 check_error();
 511                 glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
 512                 check_error();
 513
 514                 glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
 515                 check_error();
 516                 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)));
 517                 check_error();
 518                 glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
 519                 check_error();
 520                 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));
 521                 check_error();
 522                 glBindTexture(GL_TEXTURE_2D, 0);
 523                 check_error();
 524                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 525                 check_error();
 526                 GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
 527                 check_error();
 528                 assert(fence != nullptr);
 529
 530                 if (field == 1) {
 531                         // Don't upload the second field as fast as we can; wait until
 532                         // the field time has approximately passed. (Otherwise, we could
 533                         // get timing jitter against the other sources, and possibly also
 534                         // against the video display, although the latter is not as critical.)
 535                         // This requires our system clock to be reasonably close to the
 536                         // video clock, but that's not an unreasonable assumption.
 537                         timespec second_field_start;
 538                         second_field_start.tv_nsec = frame_upload_start.tv_nsec +
 539                                 frame_length * 1000000000 / TIMEBASE;
 540                         second_field_start.tv_sec = frame_upload_start.tv_sec +
 541                                 second_field_start.tv_nsec / 1000000000;
 542                         second_field_start.tv_nsec %= 1000000000;
 543
 544                         while (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
 545                                                &second_field_start, nullptr) == -1 &&
 546                                errno == EINTR) ;
 547                 }
 548
 549                 {
 550                         unique_lock<mutex> lock(bmusb_mutex);
 551                         CaptureCard::NewFrame new_frame;
 552                         new_frame.frame = frame;
 553                         new_frame.length = frame_length;
 554                         new_frame.field = field;
 555                         new_frame.interlaced = video_format.interlaced;
 556                         new_frame.ready_fence = fence;
 557                         new_frame.dropped_frames = dropped_frames;
 558                         card->new_frames.push(move(new_frame));
 559                         card->new_frames_changed.notify_all();
 560                 }
 561         }
 562 }
 563
 564 void Mixer::thread_func()
 565 {
 566         eglBindAPI(EGL_OPENGL_API);
 567         QOpenGLContext *context = create_context(mixer_surface);
 568         if (!make_current(context, mixer_surface)) {
 569                 printf("oops\n");
 570                 exit(1);
 571         }
 572
 573         struct timespec start, now;
 574         clock_gettime(CLOCK_MONOTONIC, &start);
 575
 576         int frame = 0;
 577         int stats_dropped_frames = 0;
 578
 579         while (!should_quit) {
 580                 CaptureCard::NewFrame new_frames[MAX_CARDS];
 581                 bool has_new_frame[MAX_CARDS] = { false };
 582                 int num_samples[MAX_CARDS] = { 0 };
 583
 584                 {
 585                         unique_lock<mutex> lock(bmusb_mutex);
 586
 587                         // The first card is the master timer, so wait for it to have a new frame.
 588                         // TODO: Make configurable, and with a timeout.
 589                         cards[0].new_frames_changed.wait(lock, [this]{ return !cards[0].new_frames.empty(); });
 590
 591                         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
 592                                 CaptureCard *card = &cards[card_index];
 593                                 if (card->new_frames.empty()) {
 594                                         continue;
 595                                 }
 596                                 new_frames[card_index] = move(card->new_frames.front());
 597                                 has_new_frame[card_index] = true;
 598                                 card->new_frames.pop();
 599                                 card->new_frames_changed.notify_all();
 600
 601                                 int num_samples_times_timebase = OUTPUT_FREQUENCY * new_frames[card_index].length + card->fractional_samples;
 602                                 num_samples[card_index] = num_samples_times_timebase / TIMEBASE;
 603                                 card->fractional_samples = num_samples_times_timebase % TIMEBASE;
 604                                 assert(num_samples[card_index] >= 0);
 605                         }
 606                 }
 607
 608                 // Resample the audio as needed, including from previously dropped frames.
 609                 assert(num_cards > 0);
 610                 for (unsigned frame_num = 0; frame_num < new_frames[0].dropped_frames + 1; ++frame_num) {
 611                         {
 612                                 // Signal to the audio thread to process this frame.
 613                                 unique_lock<mutex> lock(audio_mutex);
 614                                 audio_task_queue.push(AudioTask{pts_int, num_samples[0]});
 615                                 audio_task_queue_changed.notify_one();
 616                         }
 617                         if (frame_num != new_frames[0].dropped_frames) {
 618                                 // For dropped frames, increase the pts. Note that if the format changed
 619                                 // in the meantime, we have no way of detecting that; we just have to
 620                                 // assume the frame length is always the same.
 621                                 ++stats_dropped_frames;
 622                                 pts_int += new_frames[0].length;
 623                         }
 624                 }
 625
 626                 if (audio_level_callback != nullptr) {
 627                         unique_lock<mutex> lock(compressor_mutex);
 628                         double loudness_s = r128.loudness_S();
 629                         double loudness_i = r128.integrated();
 630                         double loudness_range_low = r128.range_min();
 631                         double loudness_range_high = r128.range_max();
 632
 633                         audio_level_callback(loudness_s, 20.0 * log10(peak),
 634                                              loudness_i, loudness_range_low, loudness_range_high,
 635                                              gain_staging_db, 20.0 * log10(final_makeup_gain),
 636                                              correlation.get_correlation());
 637                 }
 638
 639                 for (unsigned card_index = 1; card_index < num_cards; ++card_index) {
 640                         if (!has_new_frame[card_index]) {
 641                                 continue;
 642                         }
 643                         if (new_frames[card_index].frame->len == 0) {
 644                                 ++new_frames[card_index].dropped_frames;
 645                         }
 646                         if (new_frames[card_index].dropped_frames > 0) {
 647                                 printf("Card %u dropped %d frames before this\n",
 648                                         card_index, int(new_frames[card_index].dropped_frames));
 649                         }
 650                 }
 651
 652                 // If the first card is reporting a corrupted or otherwise dropped frame,
 653                 // just increase the pts (skipping over this frame) and don't try to compute anything new.
 654                 if (new_frames[0].frame->len == 0) {
 655                         ++stats_dropped_frames;
 656                         pts_int += new_frames[0].length;
 657                         continue;
 658                 }
 659
 660                 for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
 661                         if (!has_new_frame[card_index] || new_frames[card_index].frame->len == 0)
 662                                 continue;
 663
 664                         CaptureCard::NewFrame *new_frame = &new_frames[card_index];
 665                         assert(new_frame->frame != nullptr);
 666                         insert_new_frame(new_frame->frame, new_frame->field, new_frame->interlaced, card_index, &input_state);
 667                         check_error();
 668
 669                         // The new texture might still be uploaded,
 670                         // tell the GPU to wait until it's there.
 671                         if (new_frame->ready_fence) {
 672                                 glWaitSync(new_frame->ready_fence, /*flags=*/0, GL_TIMEOUT_IGNORED);
 673                                 check_error();
 674                                 glDeleteSync(new_frame->ready_fence);
 675                                 check_error();
 676                         }
 677                 }
 678
 679                 // Get the main chain from the theme, and set its state immediately.
 680                 Theme::Chain theme_main_chain = theme->get_chain(0, pts(), WIDTH, HEIGHT, input_state);
 681                 EffectChain *chain = theme_main_chain.chain;
 682                 theme_main_chain.setup_chain();
 683                 //theme_main_chain.chain->enable_phase_timing(true);
 684
 685                 GLuint y_tex, cbcr_tex;
 686                 bool got_frame = h264_encoder->begin_frame(&y_tex, &cbcr_tex);
 687                 assert(got_frame);
 688
 689                 // Render main chain.
 690                 GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
 691                 GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, WIDTH, HEIGHT);  // Saves texture bandwidth, although dithering gets messed up.
 692                 GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
 693                 check_error();
 694                 chain->render_to_fbo(fbo, WIDTH, HEIGHT);
 695                 resource_pool->release_fbo(fbo);
 696
 697                 subsample_chroma(cbcr_full_tex, cbcr_tex);
 698                 resource_pool->release_2d_texture(cbcr_full_tex);
 699
 700                 // Set the right state for rgba_tex.
 701                 glBindFramebuffer(GL_FRAMEBUFFER, 0);
 702                 glBindTexture(GL_TEXTURE_2D, rgba_tex);
 703                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 704                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 705                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 706
 707                 RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
 708                 check_error();
 709
 710                 const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampling_queue.h. TODO: Make less hard-coded.
 711                 h264_encoder->end_frame(fence, pts_int + av_delay, theme_main_chain.input_frames);
 712                 ++frame;
 713                 pts_int += new_frames[0].length;
 714
 715                 // The live frame just shows the RGBA texture we just rendered.
 716                 // It owns rgba_tex now.
 717                 DisplayFrame live_frame;
 718                 live_frame.chain = display_chain.get();
 719                 live_frame.setup_chain = [this, rgba_tex]{
 720                         display_input->set_texture_num(rgba_tex);
 721                 };
 722                 live_frame.ready_fence = fence;
 723                 live_frame.input_frames = {};
 724                 live_frame.temp_textures = { rgba_tex };
 725                 output_channel[OUTPUT_LIVE].output_frame(live_frame);
 726
 727                 // Set up preview and any additional channels.
 728                 for (int i = 1; i < theme->get_num_channels() + 2; ++i) {
 729                         DisplayFrame display_frame;
 730                         Theme::Chain chain = theme->get_chain(i, pts(), WIDTH, HEIGHT, input_state);  // FIXME: dimensions
 731                         display_frame.chain = chain.chain;
 732                         display_frame.setup_chain = chain.setup_chain;
 733                         display_frame.ready_fence = fence;
 734                         display_frame.input_frames = chain.input_frames;
 735                         display_frame.temp_textures = {};
 736                         output_channel[i].output_frame(display_frame);
 737                 }
 738
 739                 clock_gettime(CLOCK_MONOTONIC, &now);
 740                 double elapsed = now.tv_sec - start.tv_sec +
 741                         1e-9 * (now.tv_nsec - start.tv_nsec);
 742                 if (frame % 100 == 0) {
 743                         printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
 744                                 frame, stats_dropped_frames, elapsed, frame / elapsed,
 745                                 1e3 * elapsed / frame);
 746                 //      chain->print_phase_timing();
 747                 }
 748
 749                 if (should_cut.exchange(false)) {  // Test and clear.
 750                         string filename = generate_local_dump_filename(frame);
 751                         printf("Starting new recording: %s\n", filename.c_str());
 752                         h264_encoder->shutdown();
 753                         httpd.close_output_file();
 754                         httpd.open_output_file(filename.c_str());
 755                         h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
 756                 }
 757
 758 #if 0
 759                 // Reset every 100 frames, so that local variations in frame times
 760                 // (especially for the first few frames, when the shaders are
 761                 // compiled etc.) don't make it hard to measure for the entire
 762                 // remaining duration of the program.
 763                 if (frame == 10000) {
 764                         frame = 0;
 765                         start = now;
 766                 }
 767 #endif
 768                 check_error();
 769         }
 770
 771         resource_pool->clean_context();
 772 }
 773
 774 void Mixer::audio_thread_func()
 775 {
 776         while (!should_quit) {
 777                 AudioTask task;
 778
 779                 {
 780                         unique_lock<mutex> lock(audio_mutex);
 781                         audio_task_queue_changed.wait(lock, [this]{ return !audio_task_queue.empty(); });
 782                         task = audio_task_queue.front();
 783                         audio_task_queue.pop();
 784                 }
 785
 786                 process_audio_one_frame(task.pts_int, task.num_samples);
 787         }
 788 }
 789
 790 void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
 791 {
 792         vector<float> samples_card;
 793         vector<float> samples_out;
 794
 795         // TODO: Allow mixing audio from several sources.
 796         unsigned selected_audio_card = theme->map_signal(audio_source_channel);
 797         assert(selected_audio_card < num_cards);
 798
 799         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
 800                 samples_card.resize(num_samples * 2);
 801                 {
 802                         unique_lock<mutex> lock(cards[card_index].audio_mutex);
 803                         if (!cards[card_index].resampling_queue->get_output_samples(double(frame_pts_int) / TIMEBASE, &samples_card[0], num_samples)) {
 804                                 printf("Card %d reported previous underrun.\n", card_index);
 805                         }
 806                 }
 807                 if (card_index == selected_audio_card) {
 808                         samples_out = move(samples_card);
 809                 }
 810         }
 811
 812         // Cut away everything under 120 Hz (or whatever the cutoff is);
 813         // we don't need it for voice, and it will reduce headroom
 814         // and confuse the compressor. (In particular, any hums at 50 or 60 Hz
 815         // should be dampened.)
 816         if (locut_enabled) {
 817                 locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
 818         }
 819
 820         // Apply a level compressor to get the general level right.
 821         // Basically, if it's over about -40 dBFS, we squeeze it down to that level
 822         // (or more precisely, near it, since we don't use infinite ratio),
 823         // then apply a makeup gain to get it to -14 dBFS. -14 dBFS is, of course,
 824         // entirely arbitrary, but from practical tests with speech, it seems to
 825         // put ut around -23 LUFS, so it's a reasonable starting point for later use.
 826         {
 827                 unique_lock<mutex> lock(compressor_mutex);
 828                 if (level_compressor_enabled) {
 829                         float threshold = 0.01f;   // -40 dBFS.
 830                         float ratio = 20.0f;
 831                         float attack_time = 0.5f;
 832                         float release_time = 20.0f;
 833                         float makeup_gain = pow(10.0f, (ref_level_dbfs - (-40.0f)) / 20.0f);  // +26 dB.
 834                         level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
 835                         gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
 836                 } else {
 837                         // Just apply the gain we already had.
 838                         float g = pow(10.0f, gain_staging_db / 20.0f);
 839                         for (size_t i = 0; i < samples_out.size(); ++i) {
 840                                 samples_out[i] *= g;
 841                         }
 842                 }
 843         }
 844
 845 #if 0
 846         printf("level=%f (%+5.2f dBFS) attenuation=%f (%+5.2f dB) end_result=%+5.2f dB\n",
 847                 level_compressor.get_level(), 20.0 * log10(level_compressor.get_level()),
 848                 level_compressor.get_attenuation(), 20.0 * log10(level_compressor.get_attenuation()),
 849                 20.0 * log10(level_compressor.get_level() * level_compressor.get_attenuation() * makeup_gain));
 850 #endif
 851
 852 //      float limiter_att, compressor_att;
 853
 854         // The real compressor.
 855         if (compressor_enabled) {
 856                 float threshold = pow(10.0f, compressor_threshold_dbfs / 20.0f);
 857                 float ratio = 20.0f;
 858                 float attack_time = 0.005f;
 859                 float release_time = 0.040f;
 860                 float makeup_gain = 2.0f;  // +6 dB.
 861                 compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
 862 //              compressor_att = compressor.get_attenuation();
 863         }
 864
 865         // Finally a limiter at -4 dB (so, -10 dBFS) to take out the worst peaks only.
 866         // Note that since ratio is not infinite, we could go slightly higher than this.
 867         if (limiter_enabled) {
 868                 float threshold = pow(10.0f, limiter_threshold_dbfs / 20.0f);
 869                 float ratio = 30.0f;
 870                 float attack_time = 0.0f;  // Instant.
 871                 float release_time = 0.020f;
 872                 float makeup_gain = 1.0f;  // 0 dB.
 873                 limiter.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
 874 //              limiter_att = limiter.get_attenuation();
 875         }
 876
 877 //      printf("limiter=%+5.1f  compressor=%+5.1f\n", 20.0*log10(limiter_att), 20.0*log10(compressor_att));
 878
 879         // Upsample 4x to find interpolated peak.
 880         peak_resampler.inp_data = samples_out.data();
 881         peak_resampler.inp_count = samples_out.size() / 2;
 882
 883         vector<float> interpolated_samples_out;
 884         interpolated_samples_out.resize(samples_out.size());
 885         while (peak_resampler.inp_count > 0) {  // About four iterations.
 886                 peak_resampler.out_data = &interpolated_samples_out[0];
 887                 peak_resampler.out_count = interpolated_samples_out.size() / 2;
 888                 peak_resampler.process();
 889                 size_t out_stereo_samples = interpolated_samples_out.size() / 2 - peak_resampler.out_count;
 890                 peak = max<float>(peak, find_peak(interpolated_samples_out.data(), out_stereo_samples * 2));
 891                 peak_resampler.out_data = nullptr;
 892         }
 893
 894         // At this point, we are most likely close to +0 LU, but all of our
 895         // measurements have been on raw sample values, not R128 values.
 896         // So we have a final makeup gain to get us to +0 LU; the gain
 897         // adjustments required should be relatively small, and also, the
 898         // offset shouldn't change much (only if the type of audio changes
 899         // significantly). Thus, we shoot for updating this value basically
 900         // “whenever we process buffers”, since the R128 calculation isn't exactly
 901         // something we get out per-sample.
 902         //
 903         // Note that there's a feedback loop here, so we choose a very slow filter
 904         // (half-time of 100 seconds).
 905         double target_loudness_factor, alpha;
 906         {
 907                 unique_lock<mutex> lock(compressor_mutex);
 908                 double loudness_lu = r128.loudness_M() - ref_level_lufs;
 909                 double current_makeup_lu = 20.0f * log10(final_makeup_gain);
 910                 target_loudness_factor = pow(10.0f, -loudness_lu / 20.0f);
 911
 912                 // If we're outside +/- 5 LU uncorrected, we don't count it as
 913                 // a normal signal (probably silence) and don't change the
 914                 // correction factor; just apply what we already have.
 915                 if (fabs(loudness_lu - current_makeup_lu) >= 5.0 || !final_makeup_gain_auto) {
 916                         alpha = 0.0;
 917                 } else {
 918                         // Formula adapted from
 919                         // https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter.
 920                         const double half_time_s = 100.0;
 921                         const double fc_mul_2pi_delta_t = 1.0 / (half_time_s * OUTPUT_FREQUENCY);
 922                         alpha = fc_mul_2pi_delta_t / (fc_mul_2pi_delta_t + 1.0);
 923                 }
 924
 925                 double m = final_makeup_gain;
 926                 for (size_t i = 0; i < samples_out.size(); i += 2) {
 927                         samples_out[i + 0] *= m;
 928                         samples_out[i + 1] *= m;
 929                         m += (target_loudness_factor - m) * alpha;
 930                 }
 931                 final_makeup_gain = m;
 932         }
 933
 934         // Find R128 levels and L/R correlation.
 935         vector<float> left, right;
 936         deinterleave_samples(samples_out, &left, &right);
 937         float *ptrs[] = { left.data(), right.data() };
 938         {
 939                 unique_lock<mutex> lock(compressor_mutex);
 940                 r128.process(left.size(), ptrs);
 941                 correlation.process_samples(samples_out);
 942         }
 943
 944         // Send the samples to the sound card.
 945         if (alsa) {
 946                 alsa->write(samples_out);
 947         }
 948
 949         // And finally add them to the output.
 950         h264_encoder->add_audio(frame_pts_int, move(samples_out));
 951 }
 952
 953 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
 954 {
 955         GLuint vao;
 956         glGenVertexArrays(1, &vao);
 957         check_error();
 958
 959         glBindVertexArray(vao);
 960         check_error();
 961
 962         // Extract Cb/Cr.
 963         GLuint fbo = resource_pool->create_fbo(dst_tex);
 964         glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 965         glViewport(0, 0, WIDTH/2, HEIGHT/2);
 966         check_error();
 967
 968         glUseProgram(cbcr_program_num);
 969         check_error();
 970
 971         glActiveTexture(GL_TEXTURE0);
 972         check_error();
 973         glBindTexture(GL_TEXTURE_2D, src_tex);
 974         check_error();
 975         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 976         check_error();
 977         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 978         check_error();
 979         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 980         check_error();
 981
 982         float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
 983         set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
 984
 985         glBindBuffer(GL_ARRAY_BUFFER, cbcr_vbo);
 986         check_error();
 987
 988         for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
 989                 glEnableVertexAttribArray(attr_index);
 990                 check_error();
 991                 glVertexAttribPointer(attr_index, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
 992                 check_error();
 993         }
 994
 995         glDrawArrays(GL_TRIANGLES, 0, 3);
 996         check_error();
 997
 998         for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
 999                 glDisableVertexAttribArray(attr_index);
1000                 check_error();
1001         }
1002
1003         glUseProgram(0);
1004         check_error();
1005         glBindFramebuffer(GL_FRAMEBUFFER, 0);
1006         check_error();
1007
1008         resource_pool->release_fbo(fbo);
1009         glDeleteVertexArrays(1, &vao);
1010 }
1011
1012 void Mixer::release_display_frame(DisplayFrame *frame)
1013 {
1014         for (GLuint texnum : frame->temp_textures) {
1015                 resource_pool->release_2d_texture(texnum);
1016         }
1017         frame->temp_textures.clear();
1018         frame->ready_fence.reset();
1019         frame->input_frames.clear();
1020 }
1021
1022 void Mixer::start()
1023 {
1024         mixer_thread = thread(&Mixer::thread_func, this);
1025         audio_thread = thread(&Mixer::audio_thread_func, this);
1026 }
1027
1028 void Mixer::quit()
1029 {
1030         should_quit = true;
1031         mixer_thread.join();
1032         audio_thread.join();
1033 }
1034
1035 void Mixer::transition_clicked(int transition_num)
1036 {
1037         theme->transition_clicked(transition_num, pts());
1038 }
1039
1040 void Mixer::channel_clicked(int preview_num)
1041 {
1042         theme->channel_clicked(preview_num);
1043 }
1044
1045 void Mixer::reset_meters()
1046 {
1047         peak_resampler.reset();
1048         peak = 0.0f;
1049         r128.reset();
1050         r128.integr_start();
1051         correlation.reset();
1052 }
1053
1054 void Mixer::start_mode_scanning(unsigned card_index)
1055 {
1056         assert(card_index < num_cards);
1057         if (is_mode_scanning[card_index]) {
1058                 return;
1059         }
1060         is_mode_scanning[card_index] = true;
1061         mode_scanlist[card_index].clear();
1062         for (const auto &mode : cards[card_index].capture->get_available_video_modes()) {
1063                 mode_scanlist[card_index].push_back(mode.first);
1064         }
1065         assert(!mode_scanlist[card_index].empty());
1066         mode_scanlist_index[card_index] = 0;
1067         cards[card_index].capture->set_video_mode(mode_scanlist[card_index][0]);
1068         clock_gettime(CLOCK_MONOTONIC, &last_mode_scan_change[card_index]);
1069 }
1070
1071 Mixer::OutputChannel::~OutputChannel()
1072 {
1073         if (has_current_frame) {
1074                 parent->release_display_frame(&current_frame);
1075         }
1076         if (has_ready_frame) {
1077                 parent->release_display_frame(&ready_frame);
1078         }
1079 }
1080
1081 void Mixer::OutputChannel::output_frame(DisplayFrame frame)
1082 {
1083         // Store this frame for display. Remove the ready frame if any
1084         // (it was seemingly never used).
1085         {
1086                 unique_lock<mutex> lock(frame_mutex);
1087                 if (has_ready_frame) {
1088                         parent->release_display_frame(&ready_frame);
1089                 }
1090                 ready_frame = frame;
1091                 has_ready_frame = true;
1092         }
1093
1094         if (has_new_frame_ready_callback) {
1095                 new_frame_ready_callback();
1096         }
1097 }
1098
1099 bool Mixer::OutputChannel::get_display_frame(DisplayFrame *frame)
1100 {
1101         unique_lock<mutex> lock(frame_mutex);
1102         if (!has_current_frame && !has_ready_frame) {
1103                 return false;
1104         }
1105
1106         if (has_current_frame && has_ready_frame) {
1107                 // We have a new ready frame. Toss the current one.
1108                 parent->release_display_frame(&current_frame);
1109                 has_current_frame = false;
1110         }
1111         if (has_ready_frame) {
1112                 assert(!has_current_frame);
1113                 current_frame = ready_frame;
1114                 ready_frame.ready_fence.reset();  // Drop the refcount.
1115                 ready_frame.input_frames.clear();  // Drop the refcounts.
1116                 has_current_frame = true;
1117                 has_ready_frame = false;
1118         }
1119
1120         *frame = current_frame;
1121         return true;
1122 }
1123
1124 void Mixer::OutputChannel::set_frame_ready_callback(Mixer::new_frame_ready_callback_t callback)
1125 {
1126         new_frame_ready_callback = callback;
1127         has_new_frame_ready_callback = true;
1128 }