Could DVD drive alter the DVD disc?

[kenny1999]

Just wondering if a DVD disc could be altered by a DVD drive in any way.

A blank DVD +-R disc is physically changed after being burnt with files. There must be something changed in its atoms/particles somewhere inside the disc.

Is it true?

However, if the disc is already closed and complete, unless it is a rewrittable disc or DVD+R, there could be no further possible change to the disc again. i.e. DVD-R

Recently I am dealing with a video DVD containing bad sector, it's an original and legal copy bought from some media retails. I've spent quite some time studying about it. I encountered a program which states it could fix the bad sector on the DVD.

I am just wondering, if there is any software/utility/tool in the world which could ''fix'' the bad sector on the disc? Most generic DVD drive is for reading and writing disc. At first I thought it was impossible to physically alter the disc by any means, but when I become realized that ''writing to a disc'' is actually physically changing a disc. I start to suspect if a DVD drive could fix the bad sector on a DVD disc.

What do you think?

I am actually quite worried that my precise original DVD disc would be altered by the DVD drive, after trying with lots of decryption software - AnyDVD, DVDFab, ImgBurn etc, which some of them usually claims ''break'' , ''remove'', ''fix'' your DVD.

I'd like to know the truth.

[foxyshadis]

That program's claims are bunk, it'd have to violate the laws of physics. You can use the writing laser to permanently burn out a DVD-R, but that would require firmware hacks to override the safety protections, and there's no way they could ever rewrite any portion of one into anything readable. Since pressed DVDs are metal-based instead of dye-based or dye-metal hybrid, it would take enormously more energy to affect a pressed DVD at all.

The closest you could get is IsoPuzzle, which skips over bad sectors (and skips around the disc to get as much as it can if you've got lots of bad sectors).

[Ghitulescu]

Yes, it can.

Have a look here (http://www.plextor-digital.com/index.php/de/Technical-Topics/plexerase.html) and there (http://www.tomshardware.com/news/plextor-plexeraser,3655.html).

I never used this "facility", though.

It is also possible to alter a DCR/DVDR via reading, as the laser intensity is still high (8 times less), especially the regions that have been at limit, due to a less than ideal recording phase. These error should be corrected though by the drive before being passed to the user.

[foxyshadis]

[COLOR="Red"]Have a look here (http://www.plextor-digital.com/index.php/de/Technical-Topics/plexerase.html) and there (http://www.tomshardware.com/news/plextor-plexeraser,3655.html).

Those are still only for recordable media, not pressed media, and it only destroys sectors, rather than rewriting them.

[kenny1999]

Those are still only for recordable media, not pressed media, and it only destroys sectors, rather than rewriting them.

Excuse me, can you please explain what's the difference (physically) between recordable media and pressed media? My understanding is only limited to DVD+R， DVD-R , DVD+RW , DVD -RW something like that.

[foxyshadis]

Non-recordable (pressed) media consists of a thin layer of aluminum on top of the transparent plastic layer that either absorbs or allows light through. It's called pressed because a metal stamper literally presses the grooves into hot plastic as it cools. Aluminum is then poured into the grooves. In dual-layer discs, aluminum is the top layer, and another semi-reflective layer using silver or silicon is underneath it. The laser can refocus on either one.

Recordable media is typically an azo-based dye between metal (gold or silver) and plastic layers, nowadays the plastic usually has data embedded to calibrate the required laser intensity. In the past, other dyes and substances have been used, but azo and azo-metal hybrids are the most durable to UV and almost universally used today. The laser basically burns away the dye to reveal the metal layer, making it permanent and irreversible. Aluminum can't be used because it reacts with the dye.

Rewritable media sandwiches a metal alloy that easily phase-changes back and forth (typically germanium, antimony or tellurium) between two dielectric layers that allow quick-cooling, which is all between the aluminum and the plastic layers. By controlling the heating and cooling process, you can keep the alloy in either a crystalline or amorphous (semi-liquid) state, where the amorphous state absorbs most of the light and crystalline passes it through. To crystallize it, you heat to 350℃; to liquify, 600℃.

In all recordable formats, the grooves are pressed into the disc during manufacturing, along with the tracking pits (in -R(W)) or phase-modulated tracking (in +R(W)), and they wobble slightly to keep the writing laser aligned, compared to the perfect spiral in regular ROM discs. DVD+R(W) is much more robust against errors and allows higher-speed reading and writing than DVD-R(W), in exchange for giving up 6mb of capacity. (There are additional improvements that are only meaningful if you write multiple sessions onto a single disc.)

[Ghitulescu]

Those are still only for recordable media, not pressed media, and it only destroys sectors, rather than rewriting them.

He said alter, changing, not rewriting :)

But yes, it can reheat the sectors again, and since the amorphous state cannot be reversed back to crystalline (as in -RW case), it would destroy the data.

And unfortunately, while a bad sector on a pressed disc cannot be changed physically, it cannot be changed "back" to a good one, because nobody knows "what good means" (or the original data) even if one, reductio ad absurdum, could change the aluminium track.

[hello_hello]

He said alter, changing, not rewriting

He was also referring to pressed discs. ;)

But yes, it can reheat the sectors again, and since the amorphous state cannot be reversed back to crystalline (as in -RW case), it would destroy the data.

The question referring to pressed discs. ;)

I am actually quite worried that my precise original DVD disc would be altered by the DVD drive, after trying with lots of decryption software - AnyDVD, DVDFab, ImgBurn etc, which some of them usually claims ''break'' , ''remove'', ''fix'' your DVD.

When they claim to "fix" the DVD it'd probably refer to copying the disc despite the bad sectors. Normally, if you tried to copy a disc with bad sectors it'd fail because the copying software thinks it can't read the disc properly. Software designed to "fix" the disc would probably know where the bad sectors are on the disc and to skip them while copying.
http://en.wikipedia.org/wiki/ARccOS_Protection

If there's bad sectors for other reasons.... other parts of the disc are scratched or badly damaged, an attempt to backup the disc could possibly still fail. Some copying software will continue copying even if there's unreadable sections, and dummy data will be used in place of the unreadable data.
The above would apply to video discs where once the disc is successfully copied you simply have video which you can burn to another disc without using copy protection. Games are a different story although some of the copy protection used for games includes bad sectors.
http://m0001.gamecopyworld.com/games/gcw_cd-backup.shtml

[Ghitulescu]

He was also referring to pressed discs. ;)

The question referring to pressed discs. ;)

Ha confused both, pressed and recorded.

I wonder why it took you so much time to react... holidays?

[hello_hello]

I wonder why it took you so much time to react... holidays?

What do you mean? :D

[kenny1999]

Those are still only for recordable media, not pressed media, and it only destroys sectors, rather than rewriting them.

I don't know if my discs is pressed or recorded, it comes with nice printed boxset.

Rewritten? Isn't it only possible to rewrite a CD+/-RW or DVD+/-RW disc? I guess most pressed disc or recorded disc for sale or distribution is not RW kind , isn't it?

[kenny1999]

He said alter, changing, not rewriting :)

But yes, it can reheat the sectors again, and since the amorphous state cannot be reversed back to crystalline (as in -RW case), it would destroy the data.

And unfortunately, while a bad sector on a pressed disc cannot be changed physically, it cannot be changed "back" to a good one, because nobody knows "what good means" (or the original data) even if one, reductio ad absurdum, could change the aluminium track.

alter the data? destroy the data?

With my generic DVD writer (ASUS), is it possible that the writer could alter or destroy anything on my pressed/recorded DVD disc? Is it a software or hardware issue??

and your article quoted - http://www.plextor-digital.com/index.php/de/Technical-Topics/plexerase.html

was something in 2006, has the kind of technology (delete/erase something) become common now? My DVD writer was bought in 2013 and it is ASUS, I think it's the most basic one because it was inexpensive.


Thank you.

[Ghitulescu]

Yes, alter.
Normally the DVD/CD/BD drives are manufactured NOT to write upon recorded data.

But Plextor had a burner modified to "erase>" already written discs.

[hello_hello]

I don't know if my discs is pressed or recorded, it comes with nice printed boxset.

Rewritten? Isn't it only possible to rewrite a CD+/-RW or DVD+/-RW disc? I guess most pressed disc or recorded disc for sale or distribution is not RW kind , isn't it?


Pressed discs are the type that you get when you buy a movie etc. There's pits physically pressed into the disc for the laser to read. About the only time you'll buy something that doesn't come on a pressed disc is if it's pirated.

All the writeable/re-writeable discs used dye to simulate the pits of a pressed disc. They're not pressed. Burners can only write to (or erase) writeable discs, not pressed discs, including those drives with some sort of erase function.

[Katie Boundary]

physics

That's really all that needs to be said :)