Backing Up DVD's

what are you using to back up the dvd's?

try out dvd shrink

http://dvdshrink.org/

these are dvd movies or dvd software discs? what software are you using to copy the dvd's with? what type of media? if you are trying to copy a dvd movie most likely it is a dual layer disc(dvd9) and you cannot fit that on regular single layer dvd-r. novacopy gave you a link to dvdshrink which is a great tool to extract out all the junk on the dvd and downsample the video without having to re-encode the entire movie and have it fit on a single layer dvd. if you are trying to do a full copy of a dvd9 disc then you will need to use dual layer dvd-r's and a writer that supports it.

we are using nero an if we use a 8 speed dvd +r which copies ok, the error is on 4 speed dvd -r, i need the -r cause my dvd doesn't play +r, some -4 4 speed do copy ok, then others get to the end and the error "could not perform end of disc-at-once" is reported.