The HDMI output of VM3909H has no scaler functionality, but scaling
is possible

with the addition of a VE805R.  

This information is also mentioned in the compatible
receiver table of VM3909H’s

 product page please refer to the link
below:

http://www.aten.com/global/en/products/professional-audiovideo/video-matrix-switches/vm3909h/#.V6foudJ96Uk