DVD is a specification, and that spec is for standard-definition video only (720x480). If you want HD video on a disc, then you would make a Blu-ray disc instead.
Perhaps a better option - export an HD file using H.264, resulting in an .mp4 file. Save to a USB thumb drive stick. Plug USB stick directly into TV. Play HD video. Some Blu-ray and DVD players also now have USB ports, same thing, plug and play with stick.