OT: cd's again... one last question....
Brian K. White
brian at aljex.com
Mon Oct 30 12:10:22 PST 2006
I think that is all easy work for a computer and a a little hardware.
Lets smash the disk into little broken car window pebbles.
I can imagine very modest easy garage hobbyist level hardware to resurface
the optical side of the shards and then scan them.
Now you have a bunch of jigsaw puzzel peices in a computer.
You really think it's all that amazing of a program to reassemble the
pieces?
I don't. Not even a little. I bet there is no end of things that can be used
to match up exact tracks from one edge to another, avan across large gaps
from missing pieces, especially with the help of the other not-missing
pieces to draw context hints from.
I bet it's even easy to have it detect mixed shards from different disks and
regroup them appropriately.
So then you have some fraction of the whole disk in the form of raw data,
not yet interpreted into files.
I think it's practically effortless at that point read some portion of the
filesystem, the portion being determined by the luck of the draw as to how
many shards are missing, and where they came from on the disk.
And remember, they always knew cd's would have lots of scratches and
manufacturing defects and other forms of degradation since day one and so
the raw data on the disk includes a significant amount of
checksum/redundancy ecc data.
And most data can actually suffer holes and still be useful to humans.
executables can't usually run unless they're perfect, but pretty much every
form of data is useful no matter how little of it survives.
I'm not saying they sell this hardware or software at compusa, but I am
saying that an average-smart college kid with a CNC machine and a pc and
pretty shallow knowledge of electronics to take apart a cd drive a run the
read head directly. or even use the same ordinary cd drive motor with a cd
sized plate mounted on it and a velcro or other surface to hold chuks of
busted cd in place instead of the cnc machine. the cnc machine would just
make it easy to write a little software to automatically find the right
orientation and distance from the center to hold a single shard and then
pass it under the read head as if it were still part of the original disk.
In fact I would be very surprised if "they" didn't have this sort of thing a
year _before_ the first audio-only cd's started hitting the stores. At least
for certain rarified values of "they". I would be utterly dumbfounded if
they didn't have it at least 5 years ago. I plain refuse to even imagine for
a second they don't have it today or that it's even very rare.
Brian K. White -- brian at aljex.com -- http://www.aljex.com/bkw/
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro BBx Linux SCO FreeBSD #callahans Satriani Filk!
----- Original Message -----
From: "John Esak" <john at valar.com>
To: "Fplist (E-mail)" <filepro-list at seaslug.org>
Sent: Saturday, October 28, 2006 5:09 PM
Subject: RE: OT: cd's again... one last question....
>> >
>> > I mean, it takes 3 minutes!!!! A pair of scissors and two or three
>> > cuts
>> > and not even the fictional CSI guys could put that data back together.
>>
>> While a normal reader won't be able to do anything with it, I would
>> suspect that special hardware could still read the >99% of the data
>> that has been untouched by the "two or three cuts". Think of it as
>> breaking an LP in several pieces -- the "data" is still nearly all
>> there, even if your standard turntable can't "read" it.
>
> Hmmm, I'm not sure this holds water... or bytes. :-) I was always under
> the impression that data written to a CD or DVD was laid down in
> relatively
> the same way as on a hard disk. Which, if true, would make reading what
> was
> left on a shard of a disk extremely difficult wouldn't it? How would you
> know which second and third level indirect blocks to *jump* to without a
> super block and all of its inode information? Yes, perhaps, you could
> read
> along one cylinder for the length of the piece, but then you would be out
> of
> luck. Wouldn't gathering all these individual snippets of information be a
> nearly impossible task... even assuming this miraculous special hardware?
> :-) Now, imagine that the data is a movie of you, the currently elected
> Senator having a fling with your illegal immigrant housekeeper...
> reorganizing the frames of a compressed data stream with this kind of a
> recovery model makes the task a zillion times harder doesn't it? And I
> use
> the fictitious word zillion purposely because technology that could do
> *any*
> of this would be very special hardware indeed. I'm doubting your
> opponent
> would have much luck in turning you out of office based on these hopes.
> :-)
> :-)
>
> Whereas, I do agree that the actually "not very analogous at all" tracks
> of
> an LP would play back tiny bits of the sound there on in perfect fidelity.
> But, oh, by the way, this all presupposes that I was making the cuts in my
> CD radially from the outside to the center... but I wasn't... :-) I was
> making them transversely in whacky zig-zag lines... didn't I mention that?
> It leaves the CD's in little jagged edged strips. :-) Okay, now you have
> to jump about 300 more years into the future to even posit that "special"
> hardware you mentioned. :-)
>
> Do I finally win a debate with you on this, or what? :-) :-)
>
> john
>
> _______________________________________________
> Filepro-list mailing list
> Filepro-list at lists.celestial.com
> http://mailman.celestial.com/mailman/listinfo/filepro-list
>
More information about the Filepro-list
mailing list