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| Posted by | Jan Willem |
| Posted on | 22/05/01 21:25 |
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Writing Methods:As we all know there are games and applications producers that try to prevent you from backing up their CD's. As we all know it's illegal to make copies of software unless you want to make a backup for personal use.
Copy protections are designed to prevent you from illegal copying, but they also prevent you from making a legal backup. If you have or buy the right drive you might be able to copy these discs without taking any illegal steps like cracks. Important for copying these discs is if it's supporting reading and writing Sub channels and in RAW mode:
From the CD Freaks Knowlegde Base. The articles are created by our Moderator and Newsposter G@M3FR3@K.
RAW Mode WritingGroups
RAW is used in different writing methods:
- MMC RAW-writing:
- Packet writing
- TAO (Track At Once)
- SAO (Session At Once)
- RAW
- SAO-RAW
There are two groups in the MMC standards:
The ATAPI commands for reading, and The MMC commands (divided into four groups) for writing.
MMC RAW-writing: Like mentioned above there are four groups/methods for writing a CD-R:
- Mode 0: Packet writing. This method is used to (re)write a CD-RW.
- Mode 1: TAO. Track At Once is needed to make MultiSession discs like data and audio.
- Mode 2: SAO. With Session At Once different tracks (for instance audio songs) are written at once without stopping or repositioning the laser of the writer before the end is reached.
- Mode 3: RAW. This is the important one... In short data is delivered in a 'smart' way by the burning software and written in a 'dumb' way by the writer. Data will not be error corrected or repaired (therefore the writer is writing in a dumb way). If this method is used, errors on the original disc will also be present on the copy. These errors are exactly what some protections (like SafeDisc) use to prevent you from copying them... The RAW method that is used here works with DAO. DAO stands for Disc At Once and does the same thing as SAO: it writes the CD at once.
Than what is SAO-RAW? SAO-RAW is nothing more than a software trick to get errors from the original disc onto the copy or back-up. This trick was first used by Wesson, creator of BlindSuite (www.blindwrite.com). Programs like DiscJuggler (www.padus.com) have used this method since the beginning to copy the 'unreadable' sectors. Unreadable does not mean that the writer cannot read the sectors, but it means the sectors are giving wrong (not compliant to the standards) information to it so that the writer will keep re-reading them and eventually will enter a "0" for these sectors.
If you want to back-up an error protected game like a game with the SafeDisc protection (which has about 10.000 error sectors in the first 5% of the disc) and the writer fills in a "0" for these sectors, the back-up will not work! The game has a build-in check to see if the error sectors are present and if they're not, it simply won't start and give a message like "Please insert the original CD"...
To prevent the writer of filling in a "0" for the error sectors a smart trick is used that works in the same way as an audio disc being written. To explain this we have to get a bit technical:
-A CD-R of 650MB has 333.000 sectors -Each sector can hold a maximum of 2352 bytes
But here's the trick: a data sector can only hold 2048 bytes per sector! This is because a data sector will have space left for the error correction (so-called CRC-check). An audio sector does not use the CRC-check because audio is corrected by the hardware and therefore it can use the full 2352 bytes per sector!
SAO-RAW uses this to write 'data in an audio way' preventing the writer from doing an error correction and therefore it will write the errors on the back-up and thus producing a succesful copy.
Conclusion:
In short RAW means the writing of uncorrected data. There are some more terms encountered with RAW like RAW-96 and RAW-16 but this is a combination of RAW and SubChannel Data which is explained here. If you want to backup copy protected CD's you will need to find a drive that is capable of RAW writing.
To find out what drive is capable of writing in this mode you can check the CloneCD site, this page, or ask at our CloneCD Forum.
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Posted by sushil (guest) on Tuesday 21 August 2007 08:52
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