GStreamer in Qt quick - qml

Question

I am trying to create a GStreamer pipeline for mp4 video in Qt quick, but I can't seem to figure out how to do so. I think that I'm missing some elements since the code compiles but wont play the video.
int main(int argc, char *argv[])
{
int ret;
gst_init (&argc, &argv);
{
QGuiApplication app(argc, argv);
GstElement *pipeline = gst_pipeline_new (NULL);
GstElement *src = gst_element_factory_make ("filesrc", "source");
GstElement *dec= gst_element_factory_make ("decodebin", "decoder");
GstElement *col = gst_element_factory_make("glcolorconvert", "color_convert");
GstElement *glupload = gst_element_factory_make("glupload",NULL);
/* the plugin must be loaded before loading the qml file to register the
* GstGLVideoItem qml item */
GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);
g_assert (src && dec && glupload && col && sink);
g_object_set (G_OBJECT (src), "location", "file: path-to-file", NULL);
gst_bin_add_many (GST_BIN (pipeline), src, glupload, dec, col, sink, NULL);
gst_element_link_many (src, glupload, dec, sink, NULL);
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
QQuickItem *videoItem;
QQuickWindow *rootObject;
/* find and set the videoItem on the sink */
rootObject = static_cast<QQuickWindow *> (engine.rootObjects().first());
videoItem = rootObject->findChild<QQuickItem *> ("videoItem");
g_assert (videoItem);
g_object_set(sink, "widget", videoItem, NULL);
rootObject->scheduleRenderJob (new SetPlaying (pipeline),
QQuickWindow::BeforeSynchronizingStage);
ret = app.exec();
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
}
gst_deinit ();
return ret;
}