I'm using iDVD for simple DVD authoring. iDVD has a problem interpreting 720x486 media. It expects 720x480, when it sees 486, iDVD squashes the vertical resolution, resulting it a DVD that looks letterboxed rather than full frame.
Can I create a Media100HD project in 720x480 to start with?
For projects already in 720x486, is there a way to crop the by-reference export option to 480?
yes. just select a native 720x480 codec in your media settings, such as dv or dvcpro. stay away from media100i and media100hd codecs if you want to be doing dvd exports with apple programs, such as idvd or compressor.