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