app/main.cpp

   1 #define GST_USE_UNSTABLE_API
   2 #define HAVE_MEMFD_CREATE
   3
   4 #include <string>
   5 #include <iostream>
   6 #include <cstring>
   7 #include <cstdio>
   8 #include <cstdlib>
   9
  10 #include <signal.h>
  11 #include <wayland-client.h>
  12 #include <sys/mman.h>
  13 #include <unistd.h>
  14 #include <fcntl.h>
  15 #include <assert.h>
  16
  17 #include "xdg-shell-client-protocol.h"
  18 #include "agl-shell-desktop-client-protocol.h"
  19 #include "utils.h"
  20
  21 #include <gst/gst.h>
  22
  23 #include <gst/video/videooverlay.h>
  24 #include <gst/wayland/wayland.h>
  25
  26 #define DEFAULT_VIDEO_DEVICE    "/dev/video0"
  27
  28 // these only applies if the window is a dialog/pop-up one
  29 // by default the compositor make the window maximized
  30 #define WINDOW_WIDTH_SIZE       640
  31 #define WINDOW_HEIGHT_SIZE      720
  32
  33 #define WINDOW_WIDTH_POS_X      640
  34 #define WINDOW_WIDTH_POS_Y      180
  35
  36 // C++ requires a cast and we in wayland we do the cast implictly
  37 #define WL_ARRAY_FOR_EACH(pos, array, type) \
  38         for (pos = (type)(array)->data; \
  39              (const char *) pos < ((const char *) (array)->data + (array)->size); \
  40              (pos)++)
  41
  42 struct display {
  43         struct wl_display *wl_display;
  44         struct wl_registry *wl_registry;
  45         struct wl_compositor *wl_compositor;
  46         struct wl_output *wl_output;
  47         struct wl_shm *shm;
  48
  49         struct {
  50                 int width;
  51                 int height;
  52         } output_data;
  53
  54         struct xdg_wm_base *wm_base;
  55         struct agl_shell_desktop *agl_shell_desktop;
  56
  57         int has_xrgb;
  58 };
  59
  60 struct buffer {
  61         struct wl_buffer *buffer;
  62         void *shm_data;
  63         int busy;
  64 };
  65
  66 struct window {
  67         struct display *display;
  68
  69         int x, y;
  70         int width, height;
  71
  72         struct wl_surface *surface;
  73
  74         struct xdg_surface *xdg_surface;
  75         struct xdg_toplevel *xdg_toplevel;
  76         bool wait_for_configure;
  77
  78         int fullscreen, maximized;
  79
  80         struct buffer buffers[2];
  81         struct wl_callback *callback;
  82 };
  83
  84
  85 struct receiver_data {
  86         struct window *window;
  87
  88         GstElement *pipeline;
  89         GstWaylandVideo *wl_video;
  90         GstVideoOverlay *overlay;
  91 };
  92
  93 static int running = 1;
  94
  95 static void
  96 redraw(void *data, struct wl_callback *callback, uint32_t time);
  97
  98 static void
  99 paint_pixels(void *image, int padding, int width, int height, uint32_t time)
 100 {
 101         memset(image, 0x00, width * height * 4);
 102 }
 103
 104 static void
 105 buffer_release(void *data, struct wl_buffer *buffer)
 106 {
 107         struct buffer *mybuf = static_cast<struct buffer *>(data);
 108         mybuf->busy = 0;
 109 }
 110
 111 static const struct wl_buffer_listener buffer_listener = {
 112         buffer_release
 113 };
 114
 115
 116 static int
 117 create_shm_buffer(struct display *display, struct buffer *buffer,
 118                   int width, int height, uint32_t format)
 119 {
 120         struct wl_shm_pool *pool;
 121         int fd, size, stride;
 122         void *data;
 123
 124         stride = width * 4;
 125         size = stride * height;
 126
 127         fd = os_create_anonymous_file(size);
 128         if (fd < 0) {
 129                 fprintf(stderr, "creating a buffer file for %d B failed: %s\n",
 130                                 size, strerror(errno));
 131                 return -1;
 132         }
 133
 134         data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 135         if (data == MAP_FAILED) {
 136                 fprintf(stderr, "mmap failed: %s\n", strerror(errno));
 137                 close(fd);
 138                 return -1;
 139         }
 140
 141         pool = wl_shm_create_pool(display->shm, fd, size);
 142         buffer->buffer = wl_shm_pool_create_buffer(pool, 0, width,
 143                                                    height, stride, format);
 144         wl_buffer_add_listener(buffer->buffer, &buffer_listener, buffer);
 145         wl_shm_pool_destroy(pool);
 146         close(fd);
 147
 148         buffer->shm_data = data;
 149         fprintf(stdout, "Created shm buffer with width %d, height %d\n", width, height);
 150         return 0;
 151 }
 152
 153 static struct buffer *
 154 get_next_buffer(struct window *window)
 155 {
 156         struct buffer *buffer = NULL;
 157         int ret = 0;
 158
 159         /* we need to create new buffers for the resized value so discard
 160          * the 'old' one and force creation of the buffer with the newer
 161          * dimensions */
 162         if (window->wait_for_configure && window->maximized) {
 163                 if (!window->buffers[0].busy) {
 164                         wl_buffer_destroy(window->buffers[0].buffer);
 165                         window->buffers[0].buffer = NULL;
 166                         window->wait_for_configure = false;
 167                 }
 168         }
 169
 170         if (!window->buffers[0].busy) {
 171                 buffer = &window->buffers[0];
 172         } else if (!window->buffers[1].busy) {
 173                 buffer = &window->buffers[1];
 174         } else {
 175                 return NULL;
 176         }
 177
 178         if (!buffer->buffer) {
 179                 ret = create_shm_buffer(window->display, buffer, window->width,
 180                                         window->height, WL_SHM_FORMAT_XRGB8888);
 181
 182                 if (ret < 0)
 183                         return NULL;
 184
 185                 /* paint the padding */
 186                 memset(buffer->shm_data, 0x00, window->width * window->height * 4);
 187         }
 188
 189         return buffer;
 190 }
 191
 192
 193 static const struct wl_callback_listener frame_listener = {
 194         redraw
 195 };
 196
 197 static void
 198 redraw(void *data, struct wl_callback *callback, uint32_t time)
 199 {
 200         struct window *window = static_cast<struct window *>(data);
 201         struct buffer *buffer;
 202
 203         buffer = get_next_buffer(window);
 204         if (!buffer) {
 205                 fprintf(stderr,
 206                         !callback ? "Failed to create the first buffer.\n" :
 207                         "Both buffers busy at redraw(). Server bug?\n");
 208                 abort();
 209         }
 210
 211         // do the actual painting
 212         paint_pixels(buffer->shm_data, 0x0, window->width, window->height, time);
 213
 214         wl_surface_attach(window->surface, buffer->buffer, 0, 0);
 215         wl_surface_damage(window->surface, 0, 0, window->width, window->height);
 216
 217         if (callback)
 218                 wl_callback_destroy(callback);
 219
 220         window->callback = wl_surface_frame(window->surface);
 221         wl_callback_add_listener(window->callback, &frame_listener, window);
 222         wl_surface_commit(window->surface);
 223
 224         buffer->busy = 1;
 225 }
 226
 227 static void
 228 shm_format(void *data, struct wl_shm *wl_shm, uint32_t format)
 229 {
 230         struct display *d = static_cast<struct display *>(data);
 231
 232         if (format == WL_SHM_FORMAT_XRGB8888)
 233                 d->has_xrgb = true;
 234 }
 235
 236 static const struct wl_shm_listener shm_listener = {
 237         shm_format
 238 };
 239
 240 static void
 241 xdg_wm_base_ping(void *data, struct xdg_wm_base *shell, uint32_t serial)
 242 {
 243         xdg_wm_base_pong(shell, serial);
 244 }
 245
 246 static const struct xdg_wm_base_listener xdg_wm_base_listener = {
 247         xdg_wm_base_ping,
 248 };
 249
 250 static void
 251 display_handle_geometry(void *data, struct wl_output *wl_output,
 252                         int x, int y, int physical_width, int physical_height,
 253                         int subpixel, const char *make, const char *model, int transform)
 254 {
 255         (void) data;
 256         (void) wl_output;
 257         (void) x;
 258         (void) y;
 259         (void) physical_width;
 260         (void) physical_height;
 261         (void) subpixel;
 262         (void) make;
 263         (void) model;
 264         (void) transform;
 265 }
 266
 267 static void
 268 display_handle_mode(void *data, struct wl_output *wl_output, uint32_t flags,
 269                     int width, int height, int refresh)
 270 {
 271         struct display *d = static_cast<struct display *>(data);
 272
 273         if (wl_output == d->wl_output && (flags & WL_OUTPUT_MODE_CURRENT)) {
 274                 d->output_data.width = width;
 275                 d->output_data.height = height;
 276
 277                 fprintf(stdout, "Found output with width %d and height %d\n",
 278                                 d->output_data.width, d->output_data.height);
 279         }
 280 }
 281
 282 static void
 283 display_handle_scale(void *data, struct wl_output *wl_output, int scale)
 284 {
 285         (void) data;
 286         (void) wl_output;
 287         (void) scale;
 288 }
 289
 290 static void
 291 display_handle_done(void *data, struct wl_output *wl_output)
 292 {
 293         (void) data;
 294         (void) wl_output;
 295 }
 296
 297 static const struct wl_output_listener output_listener = {
 298         display_handle_geometry,
 299         display_handle_mode,
 300         display_handle_done,
 301         display_handle_scale
 302 };
 303
 304 static void
 305 application_id(void *data, struct agl_shell_desktop *agl_shell_desktop,
 306                 const char *app_id)
 307 {
 308         (void) data;
 309         (void) agl_shell_desktop;
 310         (void) app_id;
 311 }
 312
 313 static void
 314 application_id_state(void *data, struct agl_shell_desktop *agl_shell_desktop,
 315                      const char *app_id, const char *app_data,
 316                      uint32_t app_state, uint32_t app_role)
 317 {
 318         (void) data;
 319         (void) app_data;
 320         (void) agl_shell_desktop;
 321         (void) app_id;
 322         (void) app_state;
 323         (void) app_role;
 324 }
 325
 326 static const struct agl_shell_desktop_listener agl_shell_desktop_listener = {
 327         application_id,
 328         application_id_state,
 329 };
 330
 331 static void
 332 registry_handle_global(void *data, struct wl_registry *registry, uint32_t id,
 333                        const char *interface, uint32_t version)
 334 {
 335         struct display *d = static_cast<struct display *>(data);
 336
 337         if (strcmp(interface, "wl_compositor") == 0) {
 338                 d->wl_compositor =
 339                         static_cast<struct wl_compositor *>(wl_registry_bind(registry, id,
 340                                                     &wl_compositor_interface, 1));
 341         } else if (strcmp(interface, "xdg_wm_base") == 0) {
 342                 d->wm_base = static_cast<struct xdg_wm_base *>(wl_registry_bind(registry,
 343                                 id, &xdg_wm_base_interface, 1));
 344                 xdg_wm_base_add_listener(d->wm_base, &xdg_wm_base_listener, d);
 345         } else if (strcmp(interface, "wl_shm") == 0) {
 346                 d->shm = static_cast<struct wl_shm *>(wl_registry_bind(registry,
 347                                 id, &wl_shm_interface, 1));
 348                 wl_shm_add_listener(d->shm, &shm_listener, d);
 349         } else if (strcmp(interface, "agl_shell_desktop") == 0) {
 350                 d->agl_shell_desktop = static_cast<struct agl_shell_desktop *>(wl_registry_bind(registry, id,
 351                                                         &agl_shell_desktop_interface, 1));
 352                 /* as an example, show how to register for events from the compositor */
 353                 agl_shell_desktop_add_listener(d->agl_shell_desktop,
 354                                                &agl_shell_desktop_listener, d);
 355         } else if (strcmp(interface, "wl_output") == 0) {
 356                 d->wl_output = static_cast<struct wl_output *>(wl_registry_bind(registry, id,
 357                                              &wl_output_interface, 1));
 358                 wl_output_add_listener(d->wl_output, &output_listener, d);
 359         }
 360 }
 361
 362 static void
 363 registry_handle_global_remove(void *data, struct wl_registry *reg, uint32_t id)
 364 {
 365         (void) data;
 366         (void) reg;
 367         (void) id;
 368 }
 369
 370 static const struct wl_registry_listener registry_listener = {
 371         registry_handle_global,
 372         registry_handle_global_remove,
 373 };
 374
 375
 376 static void
 377 error_cb(GstBus *bus, GstMessage *msg, gpointer user_data)
 378 {
 379         struct receiver_data *d =
 380                 static_cast<struct receiver_data *>(user_data);
 381
 382         gchar *debug = NULL;
 383         GError *err = NULL;
 384
 385         gst_message_parse_error(msg, &err, &debug);
 386
 387         g_print("Error: %s\n", err->message);
 388         g_error_free(err);
 389
 390         if (debug) {
 391                 g_print("Debug details: %s\n", debug);
 392                 g_free(debug);
 393         }
 394
 395         gst_element_set_state(d->pipeline, GST_STATE_NULL);
 396 }
 397
 398 static GstBusSyncReply
 399 bus_sync_handler(GstBus *bus, GstMessage *message, gpointer user_data)
 400 {
 401         struct receiver_data *d =
 402                 static_cast<struct receiver_data *>(user_data);
 403
 404         if (gst_is_wayland_display_handle_need_context_message(message)) {
 405                 GstContext *context;
 406                 struct wl_display *display_handle = d->window->display->wl_display;
 407
 408                 context = gst_wayland_display_handle_context_new(display_handle);
 409                 d->wl_video = GST_WAYLAND_VIDEO(GST_MESSAGE_SRC(message));
 410                 gst_element_set_context(GST_ELEMENT(GST_MESSAGE_SRC(message)), context);
 411
 412                 goto drop;
 413         } else if (gst_is_video_overlay_prepare_window_handle_message(message)) {
 414                 struct wl_surface *window_handle = d->window->surface;
 415
 416                 /* GST_MESSAGE_SRC(message) will be the overlay object that we
 417                  * have to use. This may be waylandsink, but it may also be
 418                  * playbin. In the latter case, we must make sure to use
 419                  * playbin instead of waylandsink, because playbin resets the
 420                  * window handle and render_rectangle after restarting playback
 421                  * and the actual window size is lost */
 422                 d->overlay = GST_VIDEO_OVERLAY(GST_MESSAGE_SRC(message));
 423
 424                 g_print("setting window handle and size (%d x %d) w %d, h %d\n",
 425                                 d->window->x, d->window->y,
 426                                 d->window->width, d->window->height);
 427
 428                 gst_video_overlay_set_window_handle(d->overlay, (guintptr) window_handle);
 429                 gst_video_overlay_set_render_rectangle(d->overlay,
 430                                                        d->window->x, d->window->y,
 431                                                        d->window->width, d->window->height);
 432
 433                 goto drop;
 434         }
 435
 436         return GST_BUS_PASS;
 437
 438 drop:
 439         gst_message_unref(message);
 440         return GST_BUS_DROP;
 441 }
 442
 443 static void
 444 handle_xdg_surface_configure(void *data, struct xdg_surface *surface, uint32_t serial)
 445 {
 446         struct window *window = static_cast<struct window *>(data);
 447
 448         xdg_surface_ack_configure(surface, serial);
 449
 450         if (window->wait_for_configure) {
 451                 redraw(window, NULL, 0);
 452         }
 453 }
 454
 455 static const struct xdg_surface_listener xdg_surface_listener = {
 456         handle_xdg_surface_configure,
 457 };
 458
 459 static void
 460 handle_xdg_toplevel_configure(void *data, struct xdg_toplevel *xdg_toplevel,
 461                               int32_t width, int32_t height,
 462                               struct wl_array *states)
 463 {
 464         struct window *window = static_cast<struct window *>(data);
 465         uint32_t *p;
 466
 467         window->fullscreen = 0;
 468         window->maximized = 0;
 469
 470         // use our own macro as C++ can't typecast from (void *) directly
 471         WL_ARRAY_FOR_EACH(p, states, uint32_t *) {
 472                 uint32_t state = *p;
 473                 switch (state) {
 474                 case XDG_TOPLEVEL_STATE_FULLSCREEN:
 475                         window->fullscreen = 1;
 476                         break;
 477                 case XDG_TOPLEVEL_STATE_MAXIMIZED:
 478                         window->maximized = 1;
 479                         break;
 480                 }
 481         }
 482
 483         if (width > 0 && height > 0) {
 484                 if (!window->fullscreen && !window->maximized) {
 485                         window->width = width;
 486                         window->height = height;
 487                 }
 488                 window->width = width;
 489                 window->height = height;
 490         } else if (!window->fullscreen && !window->maximized) {
 491                 if (width == 0)
 492                         window->width = WINDOW_WIDTH_SIZE;
 493                 else
 494                         window->width = width;
 495
 496                 if (height == 0)
 497                         window->height = WINDOW_HEIGHT_SIZE;
 498                 else
 499                         window->height = height;
 500         }
 501
 502         /* if we've been resized set wait_for_configure to adjust the fb size
 503          * in the frame callback handler, which will also clear this up */
 504         if ((window->width > 0 && window->width != WINDOW_WIDTH_SIZE) &&
 505             (window->height > 0 && window->height != WINDOW_HEIGHT_SIZE)) {
 506                 window->wait_for_configure = true;
 507         }
 508 }
 509
 510 static void
 511 handle_xdg_toplevel_close(void *data, struct xdg_toplevel *xdg_toplevel)
 512 {
 513         running = 0;
 514 }
 515
 516 static const struct xdg_toplevel_listener xdg_toplevel_listener = {
 517         handle_xdg_toplevel_configure,
 518         handle_xdg_toplevel_close,
 519 };
 520
 521 static struct window *
 522 create_window(struct display *display, int width, int height, const char *app_id)
 523 {
 524         struct window *window;
 525
 526         assert(display->wm_base != NULL);
 527
 528         window = static_cast<struct window *>(calloc(1, sizeof(*window)));
 529         if (!window)
 530                 return NULL;
 531
 532         window->callback = NULL;
 533         window->display = display;
 534         window->width = width;
 535         window->height = height;
 536         window->surface = wl_compositor_create_surface(display->wl_compositor);
 537
 538         if (display->wm_base) {
 539                 window->xdg_surface =
 540                         xdg_wm_base_get_xdg_surface(display->wm_base, window->surface);
 541                 assert(window->xdg_surface);
 542
 543                 xdg_surface_add_listener(window->xdg_surface,
 544                                          &xdg_surface_listener, window);
 545                 window->xdg_toplevel = xdg_surface_get_toplevel(window->xdg_surface);
 546                 assert(window->xdg_toplevel);
 547
 548                 xdg_toplevel_add_listener(window->xdg_toplevel,
 549                                           &xdg_toplevel_listener, window);
 550
 551                 xdg_toplevel_set_app_id(window->xdg_toplevel, app_id);
 552
 553                 wl_surface_commit(window->surface);
 554                 window->wait_for_configure = true;
 555         }
 556
 557         return window;
 558 }
 559
 560
 561 static void
 562 destroy_window(struct window *window)
 563 {
 564         if (window->callback)
 565                 wl_callback_destroy(window->callback);
 566
 567         if (window->buffers[0].buffer)
 568                 wl_buffer_destroy(window->buffers[0].buffer);
 569         if (window->buffers[1].buffer)
 570                 wl_buffer_destroy(window->buffers[1].buffer);
 571
 572         if (window->xdg_toplevel)
 573                 xdg_toplevel_destroy(window->xdg_toplevel);
 574
 575         if (window->xdg_surface)
 576                 xdg_surface_destroy(window->xdg_surface);
 577
 578         wl_surface_destroy(window->surface);
 579         free(window);
 580 }
 581
 582 static void
 583 signal_int(int sig, siginfo_t *si, void *_unused)
 584 {
 585         running = 0;
 586 }
 587
 588 static struct display *
 589 create_display(int argc, char *argv[])
 590 {
 591         struct display *display;
 592
 593         display = static_cast<struct display *>(calloc(1, sizeof(*display)));
 594         if (display == NULL) {
 595                 fprintf(stderr, "out of memory\n");
 596                 exit(1);
 597         }
 598         display->wl_display = wl_display_connect(NULL);
 599         assert(display->wl_display);
 600
 601         display->has_xrgb = false;
 602         display->wl_registry = wl_display_get_registry(display->wl_display);
 603
 604         wl_registry_add_listener(display->wl_registry, &registry_listener, display);
 605         wl_display_roundtrip(display->wl_display);
 606
 607         if (display->shm == NULL) {
 608                 fprintf(stderr, "No wl_shm global\n");
 609                 return NULL;
 610         }
 611
 612         if (display->agl_shell_desktop == NULL) {
 613                 fprintf(stderr, "No agl_shell extension present\n");
 614                 return NULL;
 615         }
 616
 617         wl_display_roundtrip(display->wl_display);
 618
 619         if (!display->has_xrgb) {
 620                 fprintf(stderr, "WL_SHM_FORMAT_XRGB32 not available\n");
 621                 return NULL;
 622         }
 623
 624         return display;
 625 }
 626
 627 static void
 628 destroy_display(struct display *display)
 629 {
 630         if (display->shm)
 631                 wl_shm_destroy(display->shm);
 632
 633         if (display->wm_base)
 634                 xdg_wm_base_destroy(display->wm_base);
 635
 636         if (display->agl_shell_desktop)
 637                 agl_shell_desktop_destroy(display->agl_shell_desktop);
 638
 639         if (display->wl_compositor)
 640                 wl_compositor_destroy(display->wl_compositor);
 641
 642         wl_registry_destroy(display->wl_registry);
 643         wl_display_flush(display->wl_display);
 644         wl_display_disconnect(display->wl_display);
 645         free(display);
 646 }
 647
 648 int main(int argc, char *argv[])
 649 {
 650         int ret = 0;
 651         struct sigaction sa;
 652         struct receiver_data receiver_data = {};
 653         struct display *display;
 654         struct window *window;
 655         char pipeline_str[1024];
 656         GError *error = NULL;
 657         const char *app_id = "camera-gstreamer";
 658
 659         sa.sa_sigaction = signal_int;
 660         sigemptyset(&sa.sa_mask);
 661         sa.sa_flags = SA_RESETHAND | SA_SIGINFO;
 662         sigaction(SIGINT, &sa, NULL);
 663
 664         int gargc = 2;
 665         char **gargv = static_cast<char **>(calloc(2, sizeof(char *)));
 666
 667         gargv[0] = strdup(argv[0]);
 668         gargv[1] = strdup("--gst-debug-level=2");
 669
 670         memset(pipeline_str, 0, sizeof(pipeline_str));
 671         snprintf(pipeline_str, sizeof(pipeline_str), "v4l2src device=%s ! video/x-raw,width=%d,height=%d ! waylandsink",
 672                 DEFAULT_VIDEO_DEVICE, WINDOW_WIDTH_SIZE, WINDOW_HEIGHT_SIZE);
 673         gst_init(&gargc, &gargv);
 674
 675         setbuf(stdout, NULL);
 676
 677         fprintf(stdout, "Using pipeline: %s\n", pipeline_str);
 678
 679         GstElement *pipeline = gst_parse_launch(pipeline_str, &error);
 680         if (error || !pipeline) {
 681                 fprintf(stderr, "gstreamer pipeline construction failed!\n");
 682                 free(argv);
 683                 return EXIT_FAILURE;
 684         }
 685
 686         receiver_data.pipeline = pipeline;
 687
 688         display = create_display(argc, argv);
 689         if (!display)
 690                 return -1;
 691
 692         // if you'd want to place the video in a pop-up/dialog type of window:
 693         // agl_shell_desktop_set_app_property(display->agl_shell_desktop, app_id,
 694         //                                 AGL_SHELL_DESKTOP_APP_ROLE_POPUP,
 695         //                                 WINDOW_WIDTH_POS_X, WINDOW_WIDTH_POS_Y,
 696         //                                 0, 0, WINDOW_WIDTH_SIZE, WINDOW_HEIGHT_SIZE,
 697         //                                 display->wl_output);
 698
 699         // we use the role to set a correspondence between the top level
 700         // surface and our application, with the previous call letting the
 701         // compositor know that we're one and the same
 702         window = create_window(display, WINDOW_WIDTH_SIZE, WINDOW_HEIGHT_SIZE, app_id);
 703
 704         if (!window) {
 705                 free(argv);
 706                 return EXIT_FAILURE;
 707         }
 708
 709         window->display = display;
 710         receiver_data.window = window;
 711
 712         /* Initialise damage to full surface, so the padding gets painted */
 713         wl_surface_damage(window->surface, 0, 0,
 714                           window->width, window->height);
 715
 716         if (!window->wait_for_configure) {
 717                 redraw(window, NULL, 0);
 718         }
 719
 720         GstBus *bus = gst_element_get_bus(pipeline);
 721         gst_bus_add_signal_watch(bus);
 722
 723         g_signal_connect(bus, "message::error", G_CALLBACK(error_cb), &receiver_data);
 724         gst_bus_set_sync_handler(bus, bus_sync_handler, &receiver_data, NULL);
 725         gst_object_unref(bus);
 726
 727         gst_element_set_state(pipeline, GST_STATE_PLAYING);
 728         fprintf(stdout, "gstreamer pipeline running\n");
 729
 730         // run the application
 731         while (running && ret != -1)
 732                 ret = wl_display_dispatch(display->wl_display);
 733
 734         destroy_window(window);
 735         destroy_display(display);
 736         free(argv);
 737
 738         gst_element_set_state(pipeline, GST_STATE_NULL);
 739         gst_object_unref(pipeline);
 740         return ret;
 741 }