Multi-session dvdr question...

[Nannyfan]

I received a set of 18 dvds and it's a mess. At least 2 of the dvds are "multi-session" discs (they look like they were made like a cd) - what causes this? Is this just a product of someone copying vcds to dvd incorrectly? I'm trying to figure out what to do about this. I received the set on Memorex dvds and I thought that was the problem with some of the other dvds with errors until I came across some multi-session dvds. I'm wondering (and, it looks like) this person knowingly sent me some bad dvds.
thanks!
Nannyfan

[debwalsh]

Forgive my ignorance, but what's a "multi-session" disc?

[Nannyfan]

Well, the best I can figure out is it is like a cd is recorded - in tracks. You know how when you copy a dvd, it copies the title track and then it copies the rest of the dvd - and a cd copies in tracks. That is what 2 of the dvds out of the 17-dvd set is doing. I didn't know a dvd could be recorded that way - that's what I'd like to find out more about from someone who does a lot of video/dvd editing/creating. Any ideas??

thanks!

[lordsmurf]

Multi-session was something created for CD and not DVD, although lots of software allows it anyway. When you burn a CD, you write the lead-in, the data, then the lead-out and TOC (table of contents). On a DVD, you write the lead-in/TOC, the data, then the lead-out. Notice the TOC is moved and merged, and is why it doesn't work well on DVD. Making a multi-sesson means you write a sesson and then leave the disc OPEN. On a DVD, it means also writing multiple lead-in/TOCs, not good. The CD just kept writing a new TOC and the spec is built so it will read the last known TOC on the disc. It is closed later, if at all, usually after writing more sessions.

Anyway, most ROM drives cannot read multi-session discs (usually just burners). DVD-Video requires a single DAO/TAO session, and it must be CLOSED with lead-out. So no DVD player will see a disc unless it is closed.