Re: CDR quality / reliability problems

Julian <JulianPAdamsNo@xxxxxxxxxxxxxxx> wrote:
On 11 Apr 2006 17:52:09 -0400, kludge@xxxxxxxxx (Scott Dorsey) wrote:

I dunno. My expectation is that it would be C1 errors, but if you can't
actually see the C1 errors, you have no real way of telling.

I mistakenly thought you previously meant C2 errors were slowing down
the read. I was talking about a privately burned CD-R. That couldn't
have intentional C1 errors put in the lead in as you suggested to tell
the drive to slow down, right?

I suppose intentional C1 errors could have been put into the lead-in
for that purpose. You'll know this is the case if you see the same
error pattern every time you play it, and on different pressings of the
same disc.

But you gotta be able to see the errors in order to know.

But there isn't any magic "read me at this speed" info on the lead-in.
It's just a minimal VTOC, then blocks of data and ECC.

Would you mind looking at the FAQ and commenting how likely the other
reasons mentioned there could cause a slow down in read speed like I
saw?

http://www.cdspeed2000.com/go.php3?link=faq_general.html#q4

I don't have any web access most of the time but I'll be able to see the
web this weekend and will check it out.

I have seen quite clearly when there are C2 errors I get a jerky line
that bounces back and forth as the drive tries to do it's best but
cannot. The phenomena I was trying to understand was where even
though CDSpeed was set to read at max, instead of getting the typical
rising curve line due to the constant rpm's / track length
relationship, I get a perfectly flat line similar to when CDSpeed is
set to read at a constant speed. No C2 errors were detected on the
disc and the line stayed perfectly flat like it was being told exactly
which speed to read at and did not try to read faster even though I
had the program set to read at max.

So it sounds like the drive is dropping into a constant speed mode for
some reason. Dunno why offhand.


Now, blank CD-Rs _do_ have some info on the lead-in about appropriate
writing speeds. There should also be some information about the
manufacturer of the disc too. Plextools will let you read this stuff
I think, but it's not on a standard glass-mastered disc, just a CD-R.

I can get the manufacturer info off the disc all right.

You might be able to get the whole data block off, which contains that
info. There isn't much else in it as I recall, though. Sonic will let
you see it as a raw hex dump if you're using the old Kodak CD-R drives.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
.

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