[tom-vdr]

After doing this all what this guidance said there seemed not to be an improvement.
But then this hint

Artifacts with default xserver intel driver
If you have an issue with 15.04's intel driver, upgrade to: https://dl.dropboxusercontent.com/u/5572..._amd64.deb and install it with dpkg -i.

gave the crucial step.
Now picture is good in SD/HD and there are distortions only in rare cases.

Thanks for good work,
the first time i have seen very good quality from vdr in HD resolution at full frame rate on my NUC Intel graphics !