How to add borders to existing m2v/mpeg2 horizontal, resolution, existing, instead, stretch

andy

What's the best and fastest way to add borders to an exsisting .m2v or mpeg2 clips?
I am trying to comply to DVD spec and right now my clips resolution are anything
but 720x480. Why was it this way? I was having issue using avisynth to add borders,
so instead used VFAPI Codec  on a horizontal croped DVD2AVI's d2v. I could re-encode
with TMPGEnc, but this would take hours; MainConcept Encoder is way faster, but it
cannot add black borders, instead stretch to full screen, so mess up aspect porportion.

Welcome any suggestions...

Thanks....