On 06/26/2013 12:52 PM, "Simon Krütt" wrote: > srcpad = gst_element_get_static_pad (demux, "src"); > (mp4test:32152): GStreamer-CRITICAL **: gst_pad_link_full: assertion > `GST_IS_PAD (srcpad)' failed Are your sure your "demux" element has a pad named "src"? The assertion here most likely means srcpad is NULL.