I wonder if the choice of encoder has an impact to the results; on a quick glance they appear to use Fraunhofer reference encoder for H.264 whereas afaik x264 is the state of art wrt subjective quality.<p>In my unprofessional opinion 8 Mbps sounds quite low for 4k h264 encoding, I would expect that sort of rate for good quality 1080p encoding (Blu-Rays being in the 20 Mbps range afaik)