7 Gb Data DVD

[applebee9]

I have a DVD that has 7 gig of data (through nero or windows file explorer).

How is that possible? and can you create a backup of it?

Thanks
AB

[killingspree]

what kind of data is on it?
pls give more details
steVe

[Latexxx]

It might just be a good old fashion dual layer dvd which is created by pressing to discs and glueing them together. These are also known as dvd 9 and most of the movies ship on them.

[Sirber]

@Latexxx

Could you give me more infos about the creation of dual-layer DVDs?

[dvd_maniac]

you can't make a backup of dual layer dvd's containing data. movies can be shrunk by making rhe bitrate smallr.data can also be zipped, but usually has to be unzipped before running it.

[jggimi]

More information that you'll ever want to know about dual-layer discs is available from The Official DVD FAQ (http://www.dvddemystified.com/dvdfaq.html). The link is in Doom9's DVD Basics (http://www.doom9.org/dvd-basics.htm) section.

[applebee9]

That was very helpful information. So then its probably a dual layer dvd. i'll just store the data on the hard disk then.

killingspree - its just a standard dvd. nothing special. its published by microsoft.

Thanks All
AB

[Latexxx]

Originally posted by jggimi
More information that you'll ever want to know about dual-layer discs is available from The Official DVD FAQ (http://www.dvddemystified.com/dvdfaq.html). The link is in Doom9's DVD Basics (http://www.doom9.org/dvd-basics.htm) section.

I had a quick on those and I didn't get any info regarding dvd manufacturing. So here is a short version.

A single layer dvd (dvd 5) is created by pressing a disc and attaching it to a another piece of plastic (yes, even a single layer dvd has two layers (or at least it should have)). This makes the dvds more fault tolerant (they don't bend as much as cds). [(This is not true)It is also required because the data on dvds is written in smaller "font" as on a regular cd and a scrach on the disc hurts many more bytes than on a cd.(but the error correction is better)]

A dual layer dvd (dvd 9) is done by storing information on the both layers and then putting them together.

Please correct me if I'm wrong.

[int 21h]

Originally posted by Latexxx
...It is also required because the data on dvds is written in smaller "font" as on a regular cd and a scrach on the disc hurts many more bytes than on a cd...


This is a common misconception. It is true that DVD data is four times as dense as CD data, but the error correction at work on DVD is in the neighborhood of 9 or 10 times more efficient than CD. Not too mention a multitude of other factors (ECC constraint length) that contribute to a better overall chance of recovering from an error.