[Slowhand] Re: Da Boss Man Pt. 1

[Almighty Geetarz]

>> Sorry for the non-EC content here. I have two issues regarding making proper discs >> suitable for trading. The first issue is with "On the Fly" disc copying. This is the 
>> method I have ALWAYS used to make a disc copy, and I had no idea that I was 
>> breaking a commandment.
>>
>> *snip*
>>
>> - Also, I have only one CD burner/drive (Samsung) and, therefore, the master's data is >> copied to my hard drive first in a temp directory; then, I have to load blanks.
 
Hey Mel,
 
This is one of those times when I think we're on the same page but using different terms.
 
As *I* use it (correct me if others use it differently), "on the fly" copying is where you use 
one (source) drive and another to burn (destination) at the same time.  The problem with 
this - as Luke has pointed out - especially a few years back with older PCs, was that if 
the reader hits any scratches, dirt, hair, dust, anything, and wants to go back and re-
read a sector, this can cause a hiccup or gap on the copy being burned. With newer 
readers that are faster than writers, and bigger buffers, you're usually okay -  most of
the time.
 
Bear with me, this is as simple as I can make it:
 
Picture it this way ... you're a passenger in a car on the highway, passing a miles long
picket fence, with some pickets painted black and some white - think of those as the
"ones" and "zeroes" of the digital CD data.  Your job is to copy down the sequence as
the car speeds along.  You can only write so fast, and as the car speeds faster and 
faster, there is a point where you can keep up - but barely.  Then, if your attention 
falters, or let's say your view is momentarily blocked by a passing truck - it's too late
because the car you're in can't slow down or stop, so there will be a gap in your record.
 
People get all touchy because of the insistence on certain software like EAC - it's due
in most cases to the fact that people don't *understand* the basic format of CD-Audio.
I'll "keep it simple" as Cheryl always insists ... CD-Audio a.k.a. "redbook audio" is a 
TOTALLY bizarre thing and is unlike the format of ANY other digital medium you will
use - not your CD-ROM (data), VideoCD, SuperVideoCD, DVD, DVD-A, Hard Drive, 
Modem, Cable Modem, Floppy Disk, heck even your cell phone uses certain types of
robust error checking and correction to ensure that the data that goes back and forth
is what was intended.
 
In short form ... this is because of certain mathmatical caluclations that are made.  
When your computer sends or receives a packet of information to receive this email, 
each block of data will have a mathmatical equation performed which will result in a
"checksum". This is compared at the receiving end and if it doesn't come out properly,
then you know the data was corrupted en route and the packet can be resent and/or
depending on the error correction routines, it can even be repaired to some degree.
 
It doesn't work the same way with CD-Audio. When CDs were invented, the engineers
never in their wildest dreams thought of this kind of problem, they designed the error
correction routines to allow for the problems that would likely be encountered with 
pressed CDs.  Here's one example - if you look at the data capacities for an audio 
CD versus those for a data mode CD-ROM, you will see that the CD-ROM has less 
room for you to use - the "missing" room is in the form of the far more robust error
correction and checksum routines present on CD-ROMs, since losing even a single
bit of data on for instance a program or file can prevent it from working altogether.
Whereas a CD has 44,100 samples PER SECOND and the error correction in the 
player can compensate for some missing samples.
 
This is ALSO why the "it sounds fine to me" test is no proof that the copy is identical
to the original - it's possible that the copy you made has a percentage of bad data,
but when you play back the copy the CD player is "fixing" the errors. This is great -
unless THAT disc gets copied, and then THAT disc gets copied, etc.  The problem
snowballs on later generations. Here's one literal example: with my older PC/soft, 
I could make a copy of the same silver (pressed) CD with both Adaptec/Roxio and
with EAC.  Both of them played perfectly on my home CD player.  Now my car 
player is a little older and has a harder time "seeing" CD-R discs since they're less
reflective.  The disc copied with EAC mounts up instantly and plays perfectly. The
Roxio copy would grind and spit a while, and either not play, or would play jerkily
because the car player had a harder time correcting for the errors.
 
As Luke mentioned, you don't have to do those old unscientific tests these days, 
since you can directly compare the copy with the source with some programs. And
also as he mentioned, much of the time about *any* program will work fine to copy
*but* unless you use a program like EAC that rechecks the data, you will need to
compare the original with the copy to make sure.  The problem is that if you don't
use EAC, and don't compare ... then you *don't* know and can't, if the copy is the 
same.
 
*snip*
 


		
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