HI Stefan, thanks for your help, I changed the variable type from gdouble to guint, same error. Here's the whole code example: #include <gst.h> #include <controller/gstcontroller.h> #include <iostream> using namespace std; // Error handler 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 ("Final de stream\n"); g_main_loop_quit (loop); break; 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); break; } default: break; } return TRUE; } static void on_pad_added (GstElement *element, GstPad *pad, gpointer data) { GstPad *sinkpad = NULL; GstElement * elemento = (GstElement *) data; /* Ahora linkeo el pad de comp con sink pad */ g_print ("Dynamic pad created, linking queue\n"); sinkpad = gst_element_get_static_pad (elemento, "sink"); gst_pad_link (pad, sinkpad); gst_object_unref(sinkpad); } int main(int argc, char *argv[]) { GMainLoop *loop = NULL; GstElement *src1, *src2,*dec1,*dec2,*alfa1,*color,*smpte,*queue,*sink; GstBus *bus; guint duracion = 500.0; guint transicion = 1; /* init GStreamer */ gst_init (&argc, &argv); bool iniciado = gst_controller_init (&argc, &argv); loop = g_main_loop_new (NULL, FALSE); /* make sure we have input */ if (argc != 3) { g_print ("Usage: %s <filename1> <filename2>\n", argv[0]); return -1; } src1 = gst_element_factory_make("filesrc", "src1"); g_object_set(G_OBJECT(src1),"location",argv[1], NULL); src2 = gst_element_factory_make("filesrc", "src2"); g_object_set(G_OBJECT(src1),"location",argv[2], NULL); GstElement *pipeline = gst_pipeline_new ("video-player"); dec1 = gst_element_factory_make("decodebin2","dec1"); dec2 = gst_element_factory_make("decodebin2","dec2"); cout << "Creando pipeline..." << endl; bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline)); gst_bus_add_watch (bus, bus_call, loop); gst_object_unref (bus); alfa1 = gst_element_factory_make ("alpha","alfa1"); smpte = gst_element_factory_make ("smptealpha","smpte"); g_object_set(smpte,"type", transicion, NULL); color = gst_element_factory_make ("ffmpegcolorspace", "color"); GstElement * mixer = gst_element_factory_make("videomixer", "mixer"); if ((!alfa1) || (!smpte) || (!color) || (!mixer)) { g_printerr ("Alguno de los elementos del Bin no pudo ser creado. Saliendo\n"); return 0; } // Controller creation GstController * ctrl = gst_object_control_properties(G_OBJECT(smpte), "position",NULL); if (ctrl == NULL) { GST_WARNING ("No puede controlar el elemento fuente\n"); return 1; } // Todo valor GValue debe inicializarse en 0 GValue val_double = { 0, }; g_value_init (&val_double, G_TYPE_DOUBLE); // Set interpolation mode GstInterpolationControlSource * csource = gst_interpolation_control_source_new(); gst_interpolation_control_source_set_interpolation_mode(csource,GST_INTERPOLATE_LINEAR); // Seteo primer valor g_value_set_double(&val_double, 0.0); gst_interpolation_control_source_set(csource,(0 * GST_MSECOND),&val_double); // Seteo segundo valor g_value_set_double (&val_double, 1.0); gst_interpolation_control_source_set(csource,(duracion*GST_MSECOND),&val_double); gst_controller_set_control_source (ctrl, "position", GST_CONTROL_SOURCE (csource)); g_object_unref (csource); g_value_unset (&val_double); g_signal_connect (G_OBJECT (dec1), "pad-added", G_CALLBACK (on_pad_added),alfa1); g_signal_connect (G_OBJECT (dec2), "pad-added", G_CALLBACK (on_pad_added),smpte); queue = gst_element_factory_make("queue", "queue"); sink = gst_element_factory_make("autovideosink", "sink"); gst_bin_add_many (GST_BIN (pipeline),src1, src2, dec1, dec2, alfa1, smpte, mixer, queue, color, sink, NULL); gst_element_link (src1,dec1); gst_element_link (src2,dec2); gst_element_link (alfa1,mixer); gst_element_link (smpte,mixer); gst_element_link (mixer,queue); gst_element_link (queue,sink); /* now run */ gst_element_set_state (pipeline, GST_STATE_PLAYING); cout << "Playing..." << endl; g_main_loop_run (loop); /* also clean up */ gst_element_set_state (pipeline, GST_STATE_NULL); gst_object_unref (GST_OBJECT (pipeline)); return 0; } <div class="gmail_quote">2011/10/26 Stefan Sauer <<a href="mailto:ensonic@hora-obscura.de">ensonic@hora-obscura.de</a>> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <div bgcolor="#ffffff" text="#000000"><div class="im"> On 10/26/2011 03:12 AM, Rossana Guerra wrote: <blockquote type="cite"> <pre>Hi I trying to control the position property of a smptealpha element. It controls the opacity of the alpha channel,</pre> </blockquote></div> no, position controls the transition of the fade. 0.0:input1, 1.0:input2.<div class="im"> <blockquote type="cite"> <pre> it varies from 0.0 to 1.0. The duration of this setting is 500ms. I am working around this problem, it happens at runtime, I can't figure out what it's wrong. </pre> </blockquote> </div> What is not working? The code snippet looks more of less okay. Maybe you can post a full standalone example. Stefan<div class="im"> <blockquote type="cite"> <pre>Thanks and regards, Rossana Here's the code; _____________ gst_interpolation_control_source_set: assertion `G_VALUE_TYPE (value) == self->priv->type' failed // Agrego Controlador gdouble duracion = 500; </pre> </blockquote></div> guint64 duracion = 500; <blockquote type="cite"><div class="im"> <pre> GstController * ctrl = gst_object_control_properties(G_OBJECT(smpte), "position",NULL); if (ctrl == NULL) { GST_WARNING ("No puede controlar el elemento fuente\n"); return 0; } // Todo valor GValue debe inicializarse en 0 GValue val_double = { 0, }; g_value_init (&val_double, G_TYPE_DOUBLE); // Seteo modo de interpolacion GstInterpolationControlSource * csource = gst_interpolation_control_source_new(); gst_interpolation_control_source_set_interpolation_mode(csource,GST_INTERPOLATE_LINEAR); // Seteo primer valor g_value_set_double(&val_double, 0.0); gst_interpolation_control_source_set(csource,(0 * GST_MSECOND),&val_double); // Seteo segundo valor g_value_set_double (&val_double, 1.0); gst_interpolation_control_source_set(csource,(duracion*GST_MSECOND),&val_double); gst_controller_set_control_source (ctrl, "position", GST_CONTROL_SOURCE (csource)); g_object_unref (csource); g_value_unset (&val_double); </pre> </div><pre><fieldset></fieldset> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.freedesktop.org" target="_blank">gstreamer-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </pre> </blockquote> </div> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </blockquote></div>