git.sesse.net Git - nageru/blob - mixer.cpp

   1 #define GL_GLEXT_PROTOTYPES 1
   2 #define NO_SDL_GLEXT 1
   3 #define NUM_CARDS 2
   4
   5 #define WIDTH 1280
   6 #define HEIGHT 720
   7
   8 #include <epoxy/gl.h>
   9 #include <epoxy/egl.h>
  10
  11 #undef Success
  12
  13 #include <assert.h>
  14 #include <features.h>
  15 #include <math.h>
  16 #include <png.h>
  17 #include <pngconf.h>
  18 #include <setjmp.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <sys/time.h>
  22 #include <time.h>
  23 #include <mutex>
  24 #include <queue>
  25 #include <condition_variable>
  26
  27 #include <diffusion_effect.h>
  28 #include <effect.h>
  29 #include <effect_chain.h>
  30 #include <flat_input.h>
  31 #include <image_format.h>
  32 #include <init.h>
  33 #include <lift_gamma_gain_effect.h>
  34 #include <saturation_effect.h>
  35 #include <util.h>
  36 #include <ycbcr_input.h>
  37 #include <vignette_effect.h>
  38 #include <resample_effect.h>
  39 #include <resize_effect.h>
  40 #include <overlay_effect.h>
  41 #include <padding_effect.h>
  42 #include <white_balance_effect.h>
  43 #include <ycbcr.h>
  44 #include <resource_pool.h>
  45 #include <effect_util.h>
  46
  47 #include <EGL/egl.h>
  48
  49 #include "h264encode.h"
  50 #include "context.h"
  51 #include "bmusb.h"
  52 #include "pbo_frame_allocator.h"
  53 #include "ref_counted_gl_sync.h"
  54
  55 using namespace movit;
  56 using namespace std;
  57 using namespace std::placeholders;
  58
  59
  60 std::mutex bmusb_mutex;  // protects <cards>
  61
  62 struct CaptureCard {
  63         BMUSBCapture *usb;
  64
  65         // Threading stuff
  66         bool thread_initialized;
  67         QSurface *surface;
  68         QOpenGLContext *context;
  69
  70         bool new_data_ready;  // Whether new_frame contains anything.
  71         PBOFrameAllocator::Frame new_frame;
  72         GLsync new_data_ready_fence;  // Whether new_frame is ready for rendering.
  73         std::condition_variable new_data_ready_changed;  // Set whenever new_data_ready is changed.
  74 };
  75 CaptureCard cards[NUM_CARDS];
  76
  77 void bm_frame(int card_index, uint16_t timecode,
  78               FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
  79               FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)
  80 {
  81         CaptureCard *card = &cards[card_index];
  82         if (!card->thread_initialized) {
  83                 printf("initializing context for bmusb thread %d\n", card_index);
  84                 eglBindAPI(EGL_OPENGL_API);
  85                 card->context = create_context();
  86                 if (!make_current(card->context, card->surface)) {
  87                         printf("failed to create bmusb context\n");
  88                         exit(1);
  89                 }
  90                 card->thread_initialized = true;
  91         }
  92
  93         if (video_frame.len - video_offset != 1280 * 750 * 2) {
  94                 printf("dropping frame with wrong length (%ld)\n", video_frame.len - video_offset);
  95                 FILE *fp = fopen("frame.raw", "wb");
  96                 fwrite(video_frame.data, video_frame.len, 1, fp);
  97                 fclose(fp);
  98                 //exit(1);
  99                 card->usb->get_video_frame_allocator()->release_frame(video_frame);
 100                 card->usb->get_audio_frame_allocator()->release_frame(audio_frame);
 101                 return;
 102         }
 103         {
 104                 // Wait until the previous frame was consumed.
 105                 std::unique_lock<std::mutex> lock(bmusb_mutex);
 106                 card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready; });
 107         }
 108         GLuint pbo = (GLint)(intptr_t)video_frame.userdata;
 109         check_error();
 110         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
 111         check_error();
 112         glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, video_frame.size);
 113         check_error();
 114         //glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
 115         //check_error();
 116         GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
 117         check_error();
 118         assert(fence != nullptr);
 119         {
 120                 std::unique_lock<std::mutex> lock(bmusb_mutex);
 121                 card->new_data_ready = true;
 122                 card->new_frame = video_frame;
 123                 card->new_data_ready_fence = fence;
 124                 card->new_data_ready_changed.notify_all();
 125         }
 126
 127         // Video frame will be released later.
 128         card->usb->get_audio_frame_allocator()->release_frame(audio_frame);
 129 }
 130
 131 void place_rectangle(Effect *resample_effect, Effect *padding_effect, float x0, float y0, float x1, float y1)
 132 {
 133         float srcx0 = 0.0f;
 134         float srcx1 = 1.0f;
 135         float srcy0 = 0.0f;
 136         float srcy1 = 1.0f;
 137
 138         // Cull.
 139         if (x0 > 1280.0 || x1 < 0.0 || y0 > 720.0 || y1 < 0.0) {
 140                 CHECK(resample_effect->set_int("width", 1));
 141                 CHECK(resample_effect->set_int("height", 1));
 142                 CHECK(resample_effect->set_float("zoom_x", 1280.0));
 143                 CHECK(resample_effect->set_float("zoom_y", 720.0));
 144                 CHECK(padding_effect->set_int("left", 2000));
 145                 CHECK(padding_effect->set_int("top", 2000));
 146                 return;
 147         }
 148
 149         // Clip. (TODO: Clip on upper/left sides, too.)
 150         if (x1 > 1280.0) {
 151                 srcx1 = (1280.0 - x0) / (x1 - x0);
 152                 x1 = 1280.0;
 153         }
 154         if (y1 > 720.0) {
 155                 srcy1 = (720.0 - y0) / (y1 - y0);
 156                 y1 = 720.0;
 157         }
 158
 159         float x_subpixel_offset = x0 - floor(x0);
 160         float y_subpixel_offset = y0 - floor(y0);
 161
 162         // Resampling must be to an integral number of pixels. Round up,
 163         // and then add an extra pixel so we have some leeway for the border.
 164         int width = int(ceil(x1 - x0)) + 1;
 165         int height = int(ceil(y1 - y0)) + 1;
 166         CHECK(resample_effect->set_int("width", width));
 167         CHECK(resample_effect->set_int("height", height));
 168
 169         // Correct the discrepancy with zoom. (This will leave a small
 170         // excess edge of pixels and subpixels, which we'll correct for soon.)
 171         float zoom_x = (x1 - x0) / (width * (srcx1 - srcx0));
 172         float zoom_y = (y1 - y0) / (height * (srcy1 - srcy0));
 173         CHECK(resample_effect->set_float("zoom_x", zoom_x));
 174         CHECK(resample_effect->set_float("zoom_y", zoom_y));
 175         CHECK(resample_effect->set_float("zoom_center_x", 0.0f));
 176         CHECK(resample_effect->set_float("zoom_center_y", 0.0f));
 177
 178         // Padding must also be to a whole-pixel offset.
 179         CHECK(padding_effect->set_int("left", floor(x0)));
 180         CHECK(padding_effect->set_int("top", floor(y0)));
 181
 182         // Correct _that_ discrepancy by subpixel offset in the resampling.
 183         CHECK(resample_effect->set_float("left", -x_subpixel_offset / zoom_x));
 184         CHECK(resample_effect->set_float("top", -y_subpixel_offset / zoom_y));
 185
 186         // Finally, adjust the border so it is exactly where we want it.
 187         CHECK(padding_effect->set_float("border_offset_left", x_subpixel_offset));
 188         CHECK(padding_effect->set_float("border_offset_right", x1 - (floor(x0) + width)));
 189         CHECK(padding_effect->set_float("border_offset_top", y_subpixel_offset));
 190         CHECK(padding_effect->set_float("border_offset_bottom", y1 - (floor(y0) + height)));
 191 }
 192
 193 static bool quit = false;
 194
 195 void mixer_thread_func(QSurface *surface, QSurface *surface2, QSurface *surface3, QSurface *surface4)
 196 {
 197         cards[0].surface = surface3;
 198 #if NUM_CARDS == 2
 199         cards[1].surface = surface4;
 200 #endif
 201
 202         eglBindAPI(EGL_OPENGL_API);
 203         QOpenGLContext *context = create_context();
 204         if (!make_current(context, surface)) {
 205                 printf("oops\n");
 206                 exit(1);
 207         }
 208
 209         CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
 210         check_error();
 211
 212         EffectChain chain(WIDTH, HEIGHT);
 213         check_error();
 214
 215         ImageFormat inout_format;
 216         inout_format.color_space = COLORSPACE_sRGB;
 217         inout_format.gamma_curve = GAMMA_sRGB;
 218
 219         YCbCrFormat ycbcr_format;
 220         ycbcr_format.chroma_subsampling_x = 2;
 221         ycbcr_format.chroma_subsampling_y = 1;
 222         ycbcr_format.cb_x_position = 0.0;
 223         ycbcr_format.cr_x_position = 0.0;
 224         ycbcr_format.cb_y_position = 0.5;
 225         ycbcr_format.cr_y_position = 0.5;
 226         ycbcr_format.luma_coefficients = YCBCR_REC_601;
 227         ycbcr_format.full_range = false;
 228
 229         YCbCrInput *input[NUM_CARDS];
 230
 231         input[0] = new YCbCrInput(inout_format, ycbcr_format, WIDTH, HEIGHT, YCBCR_INPUT_SPLIT_Y_AND_CBCR);
 232         chain.add_input(input[0]);
 233         input[1] = new YCbCrInput(inout_format, ycbcr_format, WIDTH, HEIGHT, YCBCR_INPUT_SPLIT_Y_AND_CBCR);
 234         chain.add_input(input[1]);
 235         Effect *resample_effect = chain.add_effect(new ResampleEffect(), input[0]);
 236         Effect *padding_effect = chain.add_effect(new IntegralPaddingEffect());
 237         float border_color[] = { 0.0f, 0.0f, 0.0f, 1.0f };
 238         CHECK(padding_effect->set_vec4("border_color", border_color));
 239
 240         Effect *resample2_effect = chain.add_effect(new ResampleEffect(), input[1]);
 241         Effect *saturation_effect = chain.add_effect(new SaturationEffect());
 242         CHECK(saturation_effect->set_float("saturation", 0.3f));
 243         Effect *wb_effect = chain.add_effect(new WhiteBalanceEffect());
 244         CHECK(wb_effect->set_float("output_color_temperature", 3500.0));
 245         Effect *padding2_effect = chain.add_effect(new IntegralPaddingEffect());
 246
 247         chain.add_effect(new OverlayEffect(), padding_effect, padding2_effect);
 248
 249         ycbcr_format.chroma_subsampling_x = 1;
 250
 251         chain.add_ycbcr_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED, ycbcr_format, YCBCR_OUTPUT_SPLIT_Y_AND_CBCR);
 252         chain.set_dither_bits(8);
 253         chain.set_output_origin(OUTPUT_ORIGIN_TOP_LEFT);
 254         chain.finalize();
 255
 256         H264Encoder h264_encoder(surface2, WIDTH, HEIGHT, "test.mp4");
 257
 258         printf("Configuring first card...\n");
 259         cards[0].usb = new BMUSBCapture(0x1edb, 0xbd3b);  // 0xbd4f
 260         //cards[0].usb = new BMUSBCapture(0x1edb, 0xbd4f);
 261         cards[0].usb->set_frame_callback(std::bind(bm_frame, 0, _1, _2, _3, _4, _5, _6, _7));
 262         std::unique_ptr<PBOFrameAllocator> pbo_allocator1(new PBOFrameAllocator(1280 * 750 * 2 + 44));
 263         cards[0].usb->set_video_frame_allocator(pbo_allocator1.get());
 264         cards[0].usb->configure_card();
 265
 266         std::unique_ptr<PBOFrameAllocator> pbo_allocator2(new PBOFrameAllocator(1280 * 750 * 2 + 44));
 267         if (NUM_CARDS == 2) {
 268                 printf("Configuring second card...\n");
 269                 cards[1].usb = new BMUSBCapture(0x1edb, 0xbd4f);
 270                 cards[1].usb->set_frame_callback(std::bind(bm_frame, 1, _1, _2, _3, _4, _5, _6, _7));
 271                 cards[1].usb->set_video_frame_allocator(pbo_allocator2.get());
 272                 cards[1].usb->configure_card();
 273         }
 274
 275         BMUSBCapture::start_bm_thread();
 276
 277         for (int card_index = 0; card_index < NUM_CARDS; ++card_index) {
 278                 cards[card_index].usb->start_bm_capture();
 279         }
 280
 281         int frame = 0;
 282 #if _POSIX_C_SOURCE >= 199309L
 283         struct timespec start, now;
 284         clock_gettime(CLOCK_MONOTONIC, &start);
 285 #else
 286         struct timeval start, now;
 287         gettimeofday(&start, NULL);
 288 #endif
 289
 290         PBOFrameAllocator::Frame bmusb_current_rendering_frame[NUM_CARDS];
 291         for (int card_index = 0; card_index < NUM_CARDS; ++card_index) {
 292                 bmusb_current_rendering_frame[card_index] =
 293                         cards[card_index].usb->get_video_frame_allocator()->alloc_frame();
 294                 GLint input_tex_pbo = (GLint)(intptr_t)bmusb_current_rendering_frame[card_index].userdata;
 295                 input[card_index]->set_pixel_data(0, nullptr, input_tex_pbo);
 296                 input[card_index]->set_pixel_data(1, nullptr, input_tex_pbo);
 297                 check_error();
 298         }
 299
 300         //chain.enable_phase_timing(true);
 301
 302         // Set up stuff for NV12 conversion.
 303         ResourcePool *resource_pool = chain.get_resource_pool();
 304         GLuint chroma_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
 305
 306         // Cb/Cr shader.
 307         string cbcr_vert_shader = read_file("vs-cbcr.130.vert");
 308         string cbcr_frag_shader =
 309                 "#version 130 \n"
 310                 "in vec2 tc0; \n"
 311                 "uniform sampler2D cbcr_tex; \n"
 312                 "void main() { \n"
 313                 "    gl_FragColor = texture2D(cbcr_tex, tc0); \n"
 314                 "} \n";
 315         GLuint cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader);
 316
 317         GLuint vao;
 318         glGenVertexArrays(1, &vao);
 319         check_error();
 320
 321         while (!quit) {
 322                 ++frame;
 323
 324                 //int width0 = lrintf(848 * (1.0 + 0.2 * sin(frame * 0.02)));
 325                 int width0 = 848;
 326                 int height0 = lrintf(width0 * 9.0 / 16.0);
 327
 328                 //float top0 = 96 + 48 * sin(frame * 0.005);
 329                 //float left0 = 96 + 48 * cos(frame * 0.006);
 330                 float top0 = 48;
 331                 float left0 = 16;
 332                 float bottom0 = top0 + height0;
 333                 float right0 = left0 + width0;
 334
 335                 int width1 = 384;
 336                 int height1 = 216;
 337
 338                 float bottom1 = 720 - 48;
 339                 float right1 = 1280 - 16;
 340                 float top1 = bottom1 - height1;
 341                 float left1 = right1 - width1;
 342
 343                 float t = 0.5 + 0.5 * cos(frame * 0.006);
 344                 //float t = 0.0;
 345                 float scale0 = 1.0 + t * (1280.0 / 848.0 - 1.0);
 346                 float tx0 = 0.0 + t * (-16.0 * scale0);
 347                 float ty0 = 0.0 + t * (-48.0 * scale0);
 348
 349                 top0 = top0 * scale0 + ty0;
 350                 bottom0 = bottom0 * scale0 + ty0;
 351                 left0 = left0 * scale0 + tx0;
 352                 right0 = right0 * scale0 + tx0;
 353
 354                 top1 = top1 * scale0 + ty0;
 355                 bottom1 = bottom1 * scale0 + ty0;
 356                 left1 = left1 * scale0 + tx0;
 357                 right1 = right1 * scale0 + tx0;
 358
 359                 place_rectangle(resample_effect, padding_effect, left0, top0, right0, bottom0);
 360                 place_rectangle(resample2_effect, padding2_effect, left1, top1, right1, bottom1);
 361
 362                 CaptureCard card_copy[NUM_CARDS];
 363
 364                 {
 365                         std::unique_lock<std::mutex> lock(bmusb_mutex);
 366
 367                         // The first card is the master timer, so wait for it to have a new frame.
 368                         // TODO: Make configurable, and with a timeout.
 369                         cards[0].new_data_ready_changed.wait(lock, []{ return cards[0].new_data_ready; });
 370
 371                         for (int card_index = 0; card_index < NUM_CARDS; ++card_index) {
 372                                 CaptureCard *card = &cards[card_index];
 373                                 card_copy[card_index].usb = card->usb;
 374                                 card_copy[card_index].new_data_ready = card->new_data_ready;
 375                                 card_copy[card_index].new_frame = card->new_frame;
 376                                 card_copy[card_index].new_data_ready_fence = card->new_data_ready_fence;
 377                                 card->new_data_ready = false;
 378                                 card->new_data_ready_changed.notify_all();
 379                         }
 380                 }
 381
 382                 vector<FrameAllocator::Frame> input_frames_to_release;
 383
 384                 for (int card_index = 0; card_index < NUM_CARDS; ++card_index) {
 385                         CaptureCard *card = &card_copy[card_index];
 386                         if (!card->new_data_ready)
 387                                 continue;
 388
 389                         // Now we're done with the previous frame, so we can definitely
 390                         // release it when this is done rendering. (Actually, we could do
 391                         // it one frame earlier, but before we have a new one, there's no
 392                         // knowing when the current one is released.)
 393                         input_frames_to_release.push_back(bmusb_current_rendering_frame[card_index]);
 394                         bmusb_current_rendering_frame[card_index] = card->new_frame;
 395
 396                         // The new texture might still be uploaded,
 397                         // tell the GPU to wait until it's there.
 398                         if (card->new_data_ready_fence)
 399                                 glWaitSync(card->new_data_ready_fence, /*flags=*/0, GL_TIMEOUT_IGNORED);
 400                         check_error();
 401                         glDeleteSync(card->new_data_ready_fence);
 402                         check_error();
 403                         GLint input_tex_pbo = (GLint)(intptr_t)card->new_frame.userdata;
 404                         input[card_index]->set_pixel_data(0, (unsigned char *)BUFFER_OFFSET((1280 * 750 * 2 + 44) / 2 + 1280 * 25 + 22), input_tex_pbo);
 405                         input[card_index]->set_pixel_data(1, (unsigned char *)BUFFER_OFFSET(1280 * 25 + 22), input_tex_pbo);
 406
 407                         if (NUM_CARDS == 1) {
 408                                 // Set to the other one, too.
 409                                 input[1]->set_pixel_data(0, (unsigned char *)BUFFER_OFFSET((1280 * 750 * 2 + 44) / 2 + 1280 * 25 + 22), input_tex_pbo);
 410                                 input[1]->set_pixel_data(1, (unsigned char *)BUFFER_OFFSET(1280 * 25 + 22), input_tex_pbo);
 411                         }
 412                 }
 413
 414                 GLuint y_tex, cbcr_tex;
 415                 bool got_frame = h264_encoder.begin_frame(&y_tex, &cbcr_tex);
 416                 assert(got_frame);
 417
 418                 // Render chain.
 419                 {
 420                         GLuint ycbcr_fbo = resource_pool->create_fbo(y_tex, chroma_tex);
 421                         chain.render_to_fbo(ycbcr_fbo, WIDTH, HEIGHT);
 422                         resource_pool->release_fbo(ycbcr_fbo);
 423                 }
 424
 425                 // Set up for extraction.
 426                 float vertices[] = {
 427                         0.0f, 2.0f,
 428                         0.0f, 0.0f,
 429                         2.0f, 0.0f
 430                 };
 431
 432                 glBindVertexArray(vao);
 433                 check_error();
 434
 435                 // Extract Cb/Cr.
 436                 GLuint cbcr_fbo = resource_pool->create_fbo(cbcr_tex);
 437                 glBindFramebuffer(GL_FRAMEBUFFER, cbcr_fbo);
 438                 glViewport(0, 0, WIDTH/2, HEIGHT/2);
 439                 check_error();
 440
 441                 glUseProgram(cbcr_program_num);
 442                 check_error();
 443
 444                 glActiveTexture(GL_TEXTURE0);
 445                 check_error();
 446                 glBindTexture(GL_TEXTURE_2D, chroma_tex);
 447                 check_error();
 448                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 449                 check_error();
 450                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 451                 check_error();
 452                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 453                 check_error();
 454
 455                 float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
 456                 set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
 457
 458                 GLuint position_vbo = fill_vertex_attribute(cbcr_program_num, "position", 2, GL_FLOAT, sizeof(vertices), vertices);
 459                 GLuint texcoord_vbo = fill_vertex_attribute(cbcr_program_num, "texcoord", 2, GL_FLOAT, sizeof(vertices), vertices);  // Same as vertices.
 460
 461                 glDrawArrays(GL_TRIANGLES, 0, 3);
 462                 check_error();
 463
 464                 cleanup_vertex_attribute(cbcr_program_num, "position", position_vbo);
 465                 cleanup_vertex_attribute(cbcr_program_num, "texcoord", texcoord_vbo);
 466
 467                 glUseProgram(0);
 468                 check_error();
 469
 470                 RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
 471                 check_error();
 472
 473                 resource_pool->release_fbo(cbcr_fbo);
 474
 475                 h264_encoder.end_frame(fence, input_frames_to_release);
 476
 477
 478 #if 1
 479 #if _POSIX_C_SOURCE >= 199309L
 480                 clock_gettime(CLOCK_MONOTONIC, &now);
 481                 double elapsed = now.tv_sec - start.tv_sec +
 482                         1e-9 * (now.tv_nsec - start.tv_nsec);
 483 #else
 484                 gettimeofday(&now, NULL);
 485                 double elapsed = now.tv_sec - start.tv_sec +
 486                         1e-6 * (now.tv_usec - start.tv_usec);
 487 #endif
 488                 if (frame % 100 == 0) {
 489                         printf("%d frames in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
 490                                 frame, elapsed, frame / elapsed,
 491                                 1e3 * elapsed / frame);
 492                 //      chain.print_phase_timing();
 493                 }
 494
 495                 // Reset every 100 frames, so that local variations in frame times
 496                 // (especially for the first few frames, when the shaders are
 497                 // compiled etc.) don't make it hard to measure for the entire
 498                 // remaining duration of the program.
 499                 if (frame == 10000) {
 500                         frame = 0;
 501                         start = now;
 502                 }
 503 #endif
 504         }
 505         glDeleteVertexArrays(1, &vao);
 506         resource_pool->release_glsl_program(cbcr_program_num);
 507         resource_pool->release_2d_texture(chroma_tex);
 508         BMUSBCapture::stop_bm_thread();
 509 }
 510
 511 std::thread mixer_thread;
 512
 513 void start_mixer(QSurface *surface, QSurface *surface2, QSurface *surface3, QSurface *surface4)
 514 {
 515         mixer_thread = std::thread([surface, surface2, surface3, surface4]{
 516                 mixer_thread_func(surface, surface2, surface3, surface4);
 517         });
 518 }
 519
 520 void mixer_quit()
 521 {
 522         quit = true;
 523         mixer_thread.join();
 524 }