===================================================
= NB: Over 50% of this message is QUOTED, please =
= be more selective when quoting text =
===================================================
It has to do with what you mean by playing "correctly". Introduction of
single bit errors will likely not to even be detectable to the human ear.
However, the logical place to insert such errors is on "block" boundries.
Remember that CD-ROM ripping requires that you read the data off the disk
in blocks, but the data wasn't written in blocks, so you have to guess
how to turn the blocks into a single stream of bits. The attack is to try
to make the reader confused about how the data is to be aligned together.
If you are successful, the CD-DA can be played on any reader, but if you
copy it, the audio will be damaged (or unusable).
On Wed, 25 Aug 1999 20:27:50 +1000, Sendmail channeled "Colin Burchall" saying:
>
> Kenton A. Hoover wrote:
>
> >That would require a firmware change to the CD-ROM drive. Their technique
> is
> >quite clever -- they're inserting CRC errors deliberately, which the
> >CD-ROM units will fix when the data is copied, rendering the copy
> >inaccurate and unusable.
>
> If they introduce CRC errors, then any unit that is meant to make
> corrections based on these CRCs will produce incorrect data. This includes
> hifi CD players, which will pass incorrect information to their DACs. As
> far as I can see, there is no way to cause a CD player to play audio without
> passing the exact data that its DAC is converting to its digital output.
> Also, A CD-ROM drive playing CD-DA is performing exactly the same
> reading/error correction etc. as a CD player is, so it would have to decide
> that a data disc had been inserted in order to be tricked into not playing.
> If a disc is flagged as data, then most CD players will not play it at all.
> How can CRCs be manipulated to make a CD-ROM drive think it is reading a
> data disc, but a CD player still play it correctly as audio? I don't think
> it is possible. It might be possible to stop a CD-ROM ripping from a CD-DA
> disc, but simply playing it? Nope.
>
> -cb
>
> -----------------------------------------------------------------
> To stop getting this list send a message containing just the word
> "unsubscribe" to [EMAIL PROTECTED]
>
| Kenton A. Hoover | [EMAIL PROTECTED] |
| Private Citizen | |
| San Francisco, California | |
|===================== http://www.shockwave.org/~shibumi ====================|
| Nixon asks God, "When will unemployment go down in the US?" God |
| answers "In 20 years." "Too bad that it won't happen during my |
| lifetime," regrets Nixon. Brezhnev then asks "When will the |
| Russian people get a happy life?" "I regret it won't be during |
| my lifetime," says God. |
-----------------------------------------------------------------
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]
