Accurately seeking to frames?

I am also trying to find a very simple way to read the current video frame.
With this:

  gint64 current = 1;
  /* Query the current position in frames */
  if (gst_element_query_position (data->playbin, GST_FORMAT_DEFAULT,
&current)) {
    g_print ("Current Frame: %ld\n", current);
  }

I get a consistent readout but it does not read the actual frame number.
What is it showing me? (i.e., what value does this correspond to if not the
frame number?)
I am very new to GStreamer ...

thanks,
Ken