[twinaleblood]

Hi guys, hope somebody can help.
My question is: how can I detect whether or not a dvd is lossy sourced?
I mean, sometimes it's easy, I check the vobs with Gspot and it reports a lower video resolution than dvd standards. Other times a dvd may look lossy sourced but Gspot reports an ok resolution (so it may have been reencoded from divx to dvd). Is there a way to detect if this kind of dvds are actually lossy sourced?
Thanks in advance for your help.