why do dual layer dvds only hold 8.5GB?

mcryptic

[H]ard|Gawd
Joined
Jan 1, 2001
Messages
1,907
i was looking at the press release pictures from philips' dual layer dvd burner and i found this pic showing a disk with large spaces in-between the tracks. Then i realized that they only hold 8.5GB, when a single layer dvd hold 4.7GB, so why can't they hold 9.4GB?
 

ufot

Gawd
Joined
May 20, 2002
Messages
565
single layer holds 4.3gigs when you burn something to it. 4.3x2 = about 8.6
 

mcryptic

[H]ard|Gawd
Joined
Jan 1, 2001
Messages
1,907
4.7GB dvds hold ~4480MB, i think dual layer dvds hold less because of the way the tracks are in the second layer. I wanted to know why they are like that.
 
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