Re: [PLUG] 7.9 G DVD-R's?

[Forge <forge@dca.net>]

Jeffrey J. Nonken wrote:

> On Mon, 7 Jul 2003 14:24:50 -0400 (EDT), Martin DiViaio wrote:
>  
>
> > Lastly, let's not forget the legal ramifications. According to the
> > (infamous) DMCA, it's illegal to make a copy of any "copy protected"
> > media
> > for any purpose without the express permission of the copyright
> > holder.
> > This includes backups.
> >    
>
> Which really, really sucks. Especially when you have an autistic little girl who is clever enough to operate the DVD player but doesn't have the communications skills to understand detailed instructions. Such as: Don't spin the disc in the tray (or the box) with your finger to make it oriented properly (or just for fun) because it presses the surface against the inside of the case and scratches it. Or don't touch the surface. Or if you drop it on the floor, be particularly careful how you pick it up (or even don't pick it up, get Mommy or Daddy to do it), then call Daddy and he'll use compressed air to clean it off. 
>
> Backup copies used to be covered under "fair use." ... Don't even get me started...
>
>
>
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>
>  
Ok, the short and sweet:

Store bought (silver, pressed) DVDs are made in a complicated process.

Typically low budget films use single-sided, single-layer DVD (4.7GB), 
as it's cheapest and easiest to master, it's done just like a CD.

Higher budget films use a single-sided, dual-layer, or a single-layer, 
dual-sided disc. On SLDS, it's made like two CDs, then glued back to 
back. DLSD is made in a similar fashion, but one of the two pressings 
uses a different metal layer, different reflectivity. The laser will 
shift frequency when it reaches the end of the first layer, which allows 
it to start reading the second layer.

Dual-sided, dual-layer discs are prohibitively expensive. I haven't seen 
*any* of these on any movie, yet.

You can also, in theory, have a disc with two layers on one side and one 
layer on the other. These would be nearly as failure-prone and expensive 
as DLDS discs, though, so none of these in the wild, either.

DVDR's of either flavor burn 4.7GB, one side, one layer. one 'empty' 
layer (no ink, no foil) is used to make the disc a standard width. If 
you look along the rim of a DVD, you can see slight bubbles of the epoxy 
used to bond layers together.


What you *CAN* do: Commercial Windows software for backing up DVDRs does 
one of two things. Either it splits the two layers into two images, or 
it resamples the bitrate of the MPEG2 streams (and optionally takes some 
out) in order to make the final product fit into 4.7GB. For most movies 
you can get a 4.7G image that's Close Enough(tm), though a few flicks 
like Braveheart are so long that it's just not possible to get a 4.7GB 
image without noticable picture quality loss. Some that come to mind: 
Instant Copy, DVD Shrink, DVDXCopy. I have no idea how well any of these 
might work under Wine/WineX. I'll look into it if you'd like.

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