I have a SONY J3 with SDI output, and I've heard that I should buy a powerful computer with SDI input if I dont want to loose quality. When I capture from this, what format will I get?

I do this because of need to put material from Digi-Beta's to DVD.

What program do I need to convert from "SDI format(?)" to Mpeg2?

Were thankful for help on this matter.

BR