display image using gstreamer with c API - c

Question

i try to do a gstreamer pipeline using c API to show image for this i use this gst-launch command
gst-launch filesrc location="pluto.jpg" ! jpegdec ! ffmpegcolorspace ! videobalance saturation=0 ! freeze ! ximagesink
when i try it it work fine but when i try to convert it to c code it doesn't work someone can help me please ?
#include <gst/gst.h>
int main(int argc, char *argv[]) {
GstElement *pipeline, *jpdec, *imgf, *cod, *source, *sink;
GstBus *bus;
GstMessage *msg;
GstStateChangeReturn ret;
/* Initialize GStreamer */
gst_init (&argc, &argv);
/* Create the elements */
source = gst_element_factory_make ("filesrc", "source");
sink = gst_element_factory_make ("ximagesink", "sink");
jpdec = gst_element_factory_make ("jpegdec", "jdec");
imgf = gst_element_factory_make ("imagefreeze", "freeze");
cod = gst_element_factory_make ("ffmpegcolorspace", "ffmdec");
/* Create the empty pipeline */
pipeline = gst_pipeline_new ("test-pipeline");
if (!pipeline || !source || !sink || !jpdec || !imgf || !cod) {
g_printerr ("Not all elements could be created.\n");
return -1;
}
/* Build the pipeline */
gst_bin_add_many (GST_BIN (pipeline), source, jpdec, cod, imgf, sink, NULL);
if (gst_element_link (source, sink) != TRUE) {
g_printerr ("Elements could not be linked.\n");
gst_object_unref (pipeline);
return -1;
}
/* Modify the source's properties */
g_object_set (G_OBJECT (source), "location","pluto.jpg", NULL);
/* Start playing */
ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr ("Unable to set the pipeline to the playing state.\n");
gst_object_unref (pipeline);
return -1;
}
/* Wait until error or EOS */
bus = gst_element_get_bus (pipeline);
msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
/* Parse message */
if (msg != NULL) {
GError *err;
gchar *debug_info;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:
gst_message_parse_error (msg, &err, &debug_info);
g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
g_clear_error (&err);
g_free (debug_info);
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
break;
default:
/* We should not reach here because we only asked for ERRORs and EOS */
g_printerr ("Unexpected message received.\n");
break;
}
gst_message_unref (msg);
}
/* Free resources */
gst_object_unref (bus);
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
return 0;
}
there is the c code that i use to play image
when i compile the code i don't have errors but when i run it i have this erreur :
(test:5355): GStreamer-CRITICAL **: gst_caps_get_structure: assertion `GST_IS_CAPS (caps)' failed
(test:5355): GStreamer-CRITICAL **: gst_structure_get_int: assertion `structure != NULL' failed
Error received from element sink: Failed to create output image buffer of 0x0 pixels
Debugging information: ximagesink.c(472): gst_ximagesink_ximage_new (): /GstPipeline:test-pipeline/GstXImageSink:sink:
could not get shared memory of 0 bytes

Answer 1

Your gst_element_link is wrong. Something like:
if (gst_element_link_many (source, jpdec, cod, imgf, sink, NULL) != TRUE)
should work.
Those errors are likely a bug in xvimagesink, but you are using it wrongly. Feel free to report a bug at bugzilla.gnome.org about these assertions in case they happen with 1.0.