On monday I was able to fix the overscanning issue of my Orange Pi zero (read here).
Because fiddling around with the register values can be pretty harsh some times I decided to created a small programm to move the picture of the composite video output. You can find the project page here: https://projects.nwrk.biz/projects/allwinner-tvout
With this tool you can easily move the picture relative to its actual position by just calling :
$ sudo tvout -m -x