On Fri, Dec 16, 2011 at 9:53 AM, Michael Mol <[email protected]> wrote: > On Fri, Dec 16, 2011 at 12:25 PM, Mark Knecht <[email protected]> wrote: >> On Fri, Dec 16, 2011 at 9:06 AM, Michael Mol <[email protected]> wrote: >>> No; you'll have to decrypt, or do without the encrypted bits. >>> >>> dvdbackup is probably the closest to what you want. >>> >>> On Dec 16, 2011 11:09 AM, "Mark Knecht" <[email protected]> wrote: >>>> >>>> For archive purposes is there a simple way for me to make a >>>> bit-for-bit copy retail DVDs I've purchased? >>>> >>>> Assume that I've got the right sort of DVD drive, I guess something >>>> capable of writing dual-layer DVDs. >>>> >>>> Thanks, >>>> Mark >> >> Interesting. So even something that just copies blocks of data, like >> dd, can't be used for that purpose? >> >> I have no interest in tearing apart the DVD in any way. It was more >> about the idea of a fire causing the loss of maybe $15K-$20K >> investment over the years. I can rip all the CDs, keep the ripped >> version here to watch on the computer, and store the DVDs elsewhere, >> but that elimiates (generally) being able to watch special features >> which my wife and kid enjoy. >> >> Thanks for the info. > > I did exactly the same thing a few years ago, but it's been a long, > long time, so my memory on my process is very fuzzy. (It also involved > my first foray into RAID...I've got a couple hundred DVDs!) Go ahead, > count the number of times I qualify something with "IIRC"... > > dvdbackup can recreate the ISO images, IIRC. > > If you run a simple 'dd' on a DVD with encrypted portions, you'll get > I/O errors when it encounters the encrypted pieces. IIRC, some of the > data required to decrypt those portions is on the disc, but it's in an > out-of-the-way portion that won't show up as part of the block device. > IIRC, dvdbackup makes use of libdvdcss to decrypt the encrypted > portions[1], and writes a decrypted version of the data. *this* is why > you can't make a bit-for-bit copy; the output data would be decrypted. > > There are other, later obstacles, too; once CSS was broken, some > content publishers (Bandai USA, for example) would fudge the ISO spec > and the DVD nav specs in ways that didn't break *most* hardware DVD > players, but did tend to break players which strictly adhered to the > standards, such as ffmpeg, vlc and mplayer. It also broke dvdbackup > for me, IIRC, which is why I had to resort to vobcopy in some cases. I > expect the software angle for handling these things has gotten better, > though. > > [1] I don't know how it does it when dd would have hit an I/O error. > Obviously, my understanding of the workings of dvdbackup, dd, DVDs and > CSS encryption is flawed somehow. > > -- > :wq >
Thanks for the info. It makes it a bit clearer as to what's causing the road block vs. the sort of answer Jorg provided this morning which did nothing (as when I asked on the cd-record list a few days ago and the answer there did nothing either) to advance my knowledge on the subject. I appreciate the time it took you to respond. Thanks! Cheers, Mark
