On 23/10/06, Mike McCarty <Mike.McCarty@xxxxxxxxxxxxx> wrote:
> I'm not contradictining you, but recently I had a disk that was > scratched on the label side and would not read. I could literally see > through the scratch. I took a Black marker -Artline 70 - and coloured > over the scratch. Lo and behold- I could read the disc. This makes some sense, when you realize what is physically going on. CDROMs use forward error correction (FEC). When the number of bits in error on any given "track" are less than the critical number, then they can be corrected. What likely happened was that with a hole all the way through the metalization layer, the optics couldn't "see" the disc, and went into auto-focus, which caused the next bits not to be read due to being out of focus, effectively widening the scratch beyond the FEC capability to correct. Putting a backing on the disc may have made it so that the optics remained focussed, resulting in correctable errors. Mike
Sounds reasonable. I figured that I was helping it read the content under the scratch. Dotan Cohen http://essentialinux.com/linux-software.php http://what-is-what.com/what_is/open_office.html
