Exporting HD to DVD

I have a mix of software.

Using FCP X, but still have DVD Studio Pro 4 to make DVD's.

I have a project, 1920 x 1080, and need to get it onto a DVD (using DVDSP 4) with the best possible quality.

When I export (share) through Final Cut Pro X (Pro Res), the file is very large. Then when I import into DVDSP, that software compresses it automatically and the quality is poor.

What's the best solution here?

Thanks.