It depnds on what you mean by realtime encoding from VCR to DVD.
There is more that goes into making a DVD than simply capturing VCR composite input, encoding with MPEG-2, and burning the file onto DVD. Sure you could do that and make a data DVD, but it would not play on your standalone DVD player. What we do at work is record the file uncompressed, encode to MPEG-2 in realtime with the highest bitrate possible using a Matrox converter, then use a studio quality DVD authoring program.
What I do at home is something similar. I capture composite input, encode it, and record it to my hard drive. Then I author a DVD. That is, it is a two step process.