Why can't some CDs (namely, computer games and DVD-As) be accurately copied? Couldn't somebody create a program that sequentially copies the disk's bits directly into a file or onto another disk?

Computer games can be copied bit for bit, bad sectors and all. DVD-A can also be copied bit for bit, but as the audio tracks are encrypted all you'll have is an unreadable file.

Playstation 2 games and the like can't be copied because they contain data located outside of the normal writing area. Since Sony have full control of the production of CD/DVDs and the DVD-ROM drive they can design the DVD-ROM drive to read this data.

But then why aren't most CD copies recognized as genuine by their games?


But it is possible to create a fully functional DVD-A copy, right?

Thanks for the info!

CD burners can't burn the bits they want. The bits that we throw at them pass through several encoders, some of them hardcoded into the chips.
Copy protected CDs are pressed using parametrable encoders, allowing to get corrupted data on the CD, that leads to a special behaviour. Burners can't corrupt the data this way.

For example, the twin sector method creates two sectors with the same adress on the CD, but with different contents. The first one is read seeking forward, the second seeking backwards. A burner numbers the sector sequentially, and can't under any circumstances, burn two sectors with the same adress.

DVD-A have the decryption key pressed into the lead-in. A burner can't burn what you want into the lead-in. It is automatically generated by its internal chips.

SafeDisc burns correct data, but that makes the burners fail because it pushes the red book specification to their limits, that are very difficult for burner manufacturers to respect entierly. In short, they burn dummy sectors with nearly only pits, or only lands, unlike normal data, that have as much land as pits. It is unclear how it works, but they are usually not readable back unless pressed by a factory, and not by a consumer burner.

Thanks for the info!

Would it be difficult to reprogram or manufacture a burner that functions without any intermediary interpretation or encoding? I don't see the problem in simply turning the laser on and letting it manually burn every bit in sequential order.

Also, you mention SafeDisk's unique strategy. If a CD drive can read a SafeDisk-protected disk's unique contents, why can't it create a bit-for-bit accurate image of it?

One more question. Are there any personal CD pressers out there? Just curious.

Heh. Indie music companies defy the RIAA's standards. Why hasn't an "indie" CD Burner company created a fully customizable burner yet?

Yes, it would be quite difficult. You'd have to restart all engineering from zero : designing chips, designing optical controls...



if you skip CIRC, EFM and NRZ encoding, you end up with something completely unreadable.



This is not completely explained as far as I know. Search for "weak sectors" in CDfreaks.com optical storage forum. All that we know for sure is that the uncopiable sectors have the property of being extremely unbalanced regarding pit and lands. But that's a fact, you can generate or download a simple file on your computer, that nearly no burner will be able to backup on CD-ROM. The ability for burner to backup these files (and thus SafeDisc games) is evaluated with "sheeps" by CDfreaks. A 'three sheeps" burner can burn anything.



You can always ask a manufacturer to press a CD for you. However, it's expensive. The glass master costs about 1500 €. Then this price is distributed among all the cheap copies that you can make with it.
But pressing out-of-spec CDs must be more expensive, I think, because the manufacturer will have to spend more time on your CD.



Nobody would be able to use it

Thats amazing. I had no idea CDRs were so, err, picky about the bits they burned. I figured they were just laying out the data in tracks similar to a hard disk.