Camerabin - how to specify size of image for capture

Ian Davidson id012c3076 at
Sun Feb 2 06:45:03 PST 2014

Here is my program.  It creates 3 buttons - one to launch Camerabin, one 
to take snapshots, and one to close the camerabin.

The program works OK if you exclude the 4 lines from 104 to 107.

/* JustTheCamera.c */

#include <gtk/gtk.h>
#include <gst/gst.h>
#include <glib.h>

     GtkWidget *startsnapbutton;
     GtkWidget *snapbutton;
     GtkWidget *stopsnapbutton;

static  GstElement *camPipeline;
   GstElement *cambin;
   GstBus *cambus;
   GMainLoop *camloop;
   guint cam_bus_watch_id;

static gboolean
bus_call (GstBus     *bus,
           GstMessage *msg,
           gpointer    data)
   GMainLoop *loop = (GMainLoop *) data;
   switch (GST_MESSAGE_TYPE (msg)) {

     case GST_MESSAGE_EOS:
       g_print ("End of stream\n");
       g_main_loop_quit (loop);

     case GST_MESSAGE_ERROR: {
       gchar  *debug;
       GError *error;

       gst_message_parse_error (msg, &error, &debug);
       g_free (debug);

       g_printerr ("Error: %s\n", error->message);
       g_error_free (error);

       g_main_loop_quit (loop);

         const GstStructure *s;

         s = gst_message_get_structure (msg);

         if (gst_structure_has_name (s, "GstLaunchInterrupt")) {
           /* this application message is posted when we caught an 
interrupt and
            * we need to stop the pipeline. */
           g_print ("Interrupt: Stopping pipeline ...\n");
/*          gst_element_send_event (camPipeline, gst_event_new_eos ()); */
           gst_element_set_state (camPipeline, GST_STATE_NULL);
           g_main_loop_quit (loop);


   return TRUE;

gint delete_event( GtkWidget *widget,
                    GdkEvent  *event,
                    gpointer   data )
   g_print ("Delete_Event called\n");

/* Start the Camera - Set up camerabin.  */
void snapButtonPressed( GtkWidget *widget,
                gpointer   data )

  GstCaps *caps;

   gtk_widget_set_sensitive(startsnapbutton, FALSE);
   gtk_widget_set_sensitive(snapbutton, TRUE);
   gtk_widget_set_sensitive(stopsnapbutton, TRUE);

   camPipeline     = gst_pipeline_new ("camera");
   cambin          = gst_element_factory_make ("camerabin", "cambin1");

   camloop = g_main_loop_new (NULL, FALSE);
   if (!camPipeline || !cambin ) {
     g_printerr ("One element could not be created. Exiting.\n");
   /* Set up the pipeline */

   g_print ("Watch for the bus\n");
   cambus = gst_pipeline_get_bus (GST_PIPELINE (camPipeline));
   cam_bus_watch_id =  gst_bus_add_watch (cambus, bus_call, camloop);

   g_print ("Set the picture size\n");
   caps = gst_caps_from_string("video/x-raw, width=(int)800, 
   g_object_set (G_OBJECT (cambin), "image-capture-caps", caps, NULL);
   gst_caps_unref (caps);    /*  This unref seems to cause problems and 
may need to be commented out */

   g_print ("Add the element to the pipeline\n");
   gst_bin_add_many (GST_BIN (camPipeline), cambin, NULL);

   gst_element_set_state (camPipeline, GST_STATE_PLAYING);

   /* Iterate */
   g_main_loop_run (camloop);

   /* Out of the main loop, clean up nicely */
   g_print ("Returned, Camera Off\n");
   gst_element_set_state (camPipeline, GST_STATE_NULL);

   gst_object_unref (GST_OBJECT (camPipeline));
   g_source_remove (cam_bus_watch_id);
   g_main_loop_unref (camloop);




void snapNow( GtkWidget *widget,
                gpointer   data )
   guint lbIdle;

   g_print ("Take a picture\n");

   g_object_get(cambin, "idle", &lbIdle, NULL);
   if (lbIdle) {
     g_print("Camera is Idle\n");
   } else {
     g_print("Camera is Busy\n");

   g_signal_emit_by_name (cambin, "start-capture", NULL);

void snapOff( GtkWidget *widget,
                gpointer   data )
   g_print ("We want to stop\n");

   gst_element_post_message (GST_ELEMENT (camPipeline),
       gst_message_new_application (GST_OBJECT (camPipeline),
           gst_structure_new ("GstLaunchInterrupt",
               "message", G_TYPE_STRING, "Pipeline interrupted", NULL)));

int main( int   argc,
           char *argv[] )
     /* GtkWidget is the storage type for widgets */
     GtkWidget *window;
     GtkWidget *grid;

     /* This is called in all GTK applications. Arguments are parsed
      * from the command line and are returned to the application. */
     gtk_init (&argc, &argv);
     gst_init (&argc, &argv);

     /* Create a new window */
     window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

     gtk_window_set_title (GTK_WINDOW (window), "Camera");

     /* Here we just set a handler for delete_event that immediately
      * exits GTK. */
     g_signal_connect (window, "destroy",
                         G_CALLBACK (delete_event), NULL);

     /* Sets the border width of the window. */
     gtk_container_set_border_width (GTK_CONTAINER (window), 10);

     /* Use a grid for the buttons */
     grid = gtk_grid_new();

     /* Put the grid into the main window. */
     gtk_container_add (GTK_CONTAINER (window), grid);

      /* Snapshot Buttons. */
     startsnapbutton = gtk_button_new_with_label ("Start Camera");
     g_signal_connect (startsnapbutton, "clicked",
                         G_CALLBACK (snapButtonPressed), "Snapshot");
     gtk_grid_attach(GTK_GRID(grid), startsnapbutton, 0, 1, 1, 1);

     snapbutton = gtk_button_new_with_label ("Take Snap");
     g_signal_connect (snapbutton, "clicked",
                         G_CALLBACK (snapNow), "Snapshot");
     gtk_grid_attach(GTK_GRID(grid), snapbutton, 0, 2, 1, 1);
     gtk_widget_set_sensitive(snapbutton, FALSE);

     stopsnapbutton = gtk_button_new_with_label ("Stop Camera");
     g_signal_connect (stopsnapbutton, "clicked",
                         G_CALLBACK (snapOff), "Snapshot");
     gtk_grid_attach(GTK_GRID(grid), stopsnapbutton, 0, 3, 1, 1);
     gtk_widget_set_sensitive(stopsnapbutton, FALSE);


     gtk_widget_show (window);

     /* Rest in gtk_main and wait for the fun to begin! */
     gtk_main ();

/* JustTheCamera-end */

On 31/01/2014 14:51, Thiago Santos wrote:
> If you have a sample application/script that shows the problem, you 
> can send it to the list for other devels to look if it is correctly 
> using camerabin.
> --
> Thiago

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