Sends manually created colored frames every 1 second

send-color-buffers.c

#include <gtk/gtk.h>
#include <gst/gst.h>
#include <gst/audio/audio.h>
#include <string.h>

#define _STR(x) #x
#define STR(x) _STR(x)

#define WIDTH 640
#define HEIGHT 460
#define BUFFER_SIZE WIDTH * HEIGHT * 4

#define RED   0x000000FF
#define GREEN 0x00FF0000
#define BLUE  0x0000FF00

#define CAPS \
  "caps=video/x-raw,format=RGBx,"\
  "width=" STR(WIDTH) ","\
  "height=" STR(HEIGHT) ","\
  "framerate=30/1"


static GMainLoop *loop;
static guint feed_source_id;
static guint frame_number = 0;
static guint32 colors[] = { RED, GREEN, BLUE };



static gboolean push_data (gpointer user_data) {
  GstElement *pipeline = GST_ELEMENT (user_data);
  GstElement *src;
  GstBuffer *buffer;
  GstMapInfo map;
  GstFlowReturn ret;
  gint32 *raw_data;
  guint i;

  src = gst_bin_get_by_name (GST_BIN (pipeline), "src");

  buffer = gst_buffer_new_and_alloc (WIDTH * HEIGHT * 4);
  GST_BUFFER_TIMESTAMP (buffer) = gst_util_uint64_scale (frame_number++, GST_SECOND, 1);
  GST_BUFFER_DURATION (buffer) = gst_util_uint64_scale (1, GST_SECOND, 1);

  gst_buffer_map (buffer, &map, GST_MAP_WRITE);
  
  raw_data = (guint32 *) map.data;

  for (i = 0; i < WIDTH * HEIGHT; ++i) {
    raw_data[i] = colors[frame_number % 3];
  }

  gst_buffer_unmap (buffer, &map);
  g_signal_emit_by_name (src, "push-buffer", buffer, &ret);

  g_object_unref (src);

  if (ret != GST_FLOW_OK)
    return FALSE;

  return TRUE;
}

static void start_feed (GstElement *source, guint size, gpointer user_data) {
  if (feed_source_id == 0) {
    g_print ("Start feeding\n");
    feed_source_id = g_idle_add ((GSourceFunc) push_data, user_data);
  }
}

static void stop_feed (GstElement *source, gpointer user_data) {
  if (feed_source_id != 0) {
    g_source_remove (feed_source_id);
    feed_source_id = 0;
  }
}

static void
window_realize_cb (GtkWidget *window, gpointer user_data)
{
  GstElement *pipeline = GST_ELEMENT (user_data);
  GstElement *sink;
  GtkWidget *viewer;

  sink = gst_bin_get_by_name (GST_BIN (pipeline), "sink");
  g_object_get (G_OBJECT (sink), "widget", &viewer, NULL);

  gtk_container_add (GTK_CONTAINER (window), viewer);
  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  gtk_widget_show (viewer);

  g_object_unref (sink);
  g_object_unref (viewer);
}

int
main (int argc, char ** argv)
{
  GstElement *pipeline;
  GstElement *src;
  GtkWidget *window;

  gst_init (&argc, &argv);
  gtk_init (&argc, &argv);

  g_print ("caps: %s\n", CAPS);

  pipeline = gst_parse_launch (
      "appsrc name=src " CAPS " ! videoconvert ! gtksink name=sink", NULL);

  src = gst_bin_get_by_name (GST_BIN (pipeline), "src");
  g_signal_connect (src, "need-data", G_CALLBACK (start_feed), pipeline);
  g_signal_connect (src, "enough-data", G_CALLBACK (stop_feed), NULL);
  g_object_unref (src);

  /* Create UI */
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_default_size (GTK_WINDOW (window), WIDTH, HEIGHT);
  g_signal_connect (window, "realize", G_CALLBACK (window_realize_cb),
      pipeline);
  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);

  gtk_widget_show_all (GTK_WIDGET (window));
  gtk_main ();

  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);

  return 0;
}