I'd not even ask about a CUDA encoder to begin with. Discussion of it has popped up -many- times and it's a no go because of the extensive resources required. Unless you have
a lot of coders who are willing to put time and effort into optimizing code for CUDA, it's not happening. IIRC, one huge issue Dark Shikari had was getting functions to run fast enough to make it worthwhile.
@neuron2: Thanks for adding mkv support
No need for me to demux a mkv for doing comparisons of my encodes anymore!