Retrieve missing elements from a previous run of gst_parse_launch_full()
or gst_parse_launchv_full(). Will only return results if an error code
of GST_PARSE_ERROR_NO_SUCH_ELEMENT was returned.
a NULL-terminated array of element factory name strings of missing elements. Free with g_strfreev() when no longer needed. [transfer full][array zero-terminated=1][element-type gchar*]
Retrieve missing elements from a previous run of gst_parse_launch_full() or gst_parse_launchv_full(). Will only return results if an error code of GST_PARSE_ERROR_NO_SUCH_ELEMENT was returned.