Safedisc V2 is down

[Günni]

This is the German > English translation (Systran Professional translator)

Betablocker

" weak one " sectors
Actually one expects from a D-BURNER that he writes all data, which one sets to him forward also correctly on CD. Finally such equipment functions digitally. And nevertheless there are certain data samples, which lead to perfectly illegible, defective sectors. How can be?

The conception of the digital memory CD ROM is a simplification. Quite deeply down, under different codings and several layers error correction, is the information on CD a rather similar affair. It consists of pit and country, zones of different Reflektivitaet. During the reading this structure produces an alternating voltage, which is afterwards digitized over a photo sensor. And the problem begins exactly here. Around the similar tension into the values " 1 " and " 0 " to convert, a threshold value between the maximum values of the alternating voltage is specified. Everything over it reaches the " 1 ", everything under it to " 0 ". Normally, with an even distribution of pit and country, this functions marvelously. Are however very unevenly distributed pit and country, the resulting tension contains a DC voltage portion, which away-pushes short and thus weak signals of the threshold value. During the digitization thus error develops. Exactly for this reason there is asymmetry, limit values for the relationship of pit and country. Usually one uses however relatives a value, beta.

Unfortunately exist now some data samples, which produce exactly this asymmetry on that for CD. When this becomes so strong the fact that the developing errors cannot be corrected by the error correction no more depends among other things on pit geometry, the medium and the read drive assembly. Whether a certain combination of this problem is concerned, or whether it still gets along also with greatest possible asymmetry, one can examine max. ISO easily with the file. It contains some sectors (mode 1/2048) with the appropriate data samples. Who wants to into shape-tinker itself from it no complete image, the file can burn also directly on a CDR (or better CDRW). Since the file beginnings are exactly on sector borders (not with UDF), functioned also this.

What can one do however now, if one wants to burn these critical data samples nevertheless? Except changing the samples - nothing! That sounds itself however more badly, than it is. Because due to a characteristic of these samples it is sufficient to change few values. And these " intentional errors " knows one practical-proves in the sector in such a way to distribute that they are again out-counted by the Layered error Correction. Who wants to try it out itself, should download itself the beta blocker. This small program needs the VB5-Runtime, which should be however present ####ting from Windows 98. The function mode is simple: An image file (mode 1/2352, e.g.. Clone CD *.img) by dragee and drop in the program window pull, samples look for and, if necessary, change.

Unfortunately the method does not function yet with very strongly asymmetrical samples, and, since there are theoretically six different possibilities to distribute data in a sector the program however only one considered, possibly also not with all Rekordern. Try out is announced.