On Tue, 29 Jul 2003 16:11:18 +0000 (UTC), Jim H
wrote:

(I almost made the subject line CDR?! WTF!?)

Someone in my house has been bugging me for a while to copy some of her
DVDs onto CD (DivX) so she can watch them on her DVD-less computer. I
finally gave in and told her to get me some blank CDs.

The ones she gave me are 'audio' discs. It betrays every thread of my
rational mind to think that these are different from standard (data or
audio) cds, but then I know the music industry well enough to think that
they might be deliberately limited/protected/corrupt.

Exactly: 'audio' discs have a (digtial) marker pressed in to the
lead-in area of the disc, which is looked for by consumer standalone
CD recorders. The additional cost (much less, BTW, than it used to
be) is somehow channeled into the record industry as "compensation"
for all the copyright infringing duplicates made w/ these devices :-(

I've burned music onto bog standard CD-Rs a thousand times! Is some
perverse plot abound to exploit the naïeve into buying more expensive
media?

In terms of performance "audio" CD-Rs are equivalent to "computer"
ones. The only possible difference is that since standalone copiers
rarely operate at more than x2 the "audio" discs *may* not work as
well on higher speed computer burners. I certainly wouldn't attempt
to burn them at x24!

HTH
Julian

--
Julian Fowler
julian (at) bellevue-barn (dot) org (dot) uk

Did the copied disc also sound distorted?


That I dont recall... but given a bit of time I'll dig it out and have a
listen to a few tracks.


Thisd article is quite interesting, if inconclusive..

http://www.cdrinfo.com/Sections/Arti...eadline=Writin
g+Quality&index=0

Thanks.

In article ,
Stevie Boy wrote:
I've never myself (tad lazy in this respect) burned/copied a CD however
I do have the original and a copied version of the very same CD. This
was done by a friend at 32x on a Sony 32x writer and the difference is
shocking to say the least. The copy clearly has a much brighter balance
to it with treble emphasis.

Wonder if pre-emphasis and a faulty flag came into the equation somewhere?
I've burnt many CDs at all sorts of speeds, and found that they either
work or don't. But certainly never heard a difference in the tonal balance
- this just doesn't make sense with digits.

--
*Organized Crime Is Alive And Well; It's Called Auto Insurance. *

Dave Plowman London SW 12
RIP Acorn

"Stevie Boy" wrote in message


I've never myself (tad lazy in this respect) burned/copied a CD
however I do have the original and a copied version of the very same
CD. This was done by a friend at 32x on a Sony 32x writer and the
difference is shocking to say the least. The copy clearly has a much
brighter balance to it with treble emphasis.

What do you know about the procedures used to create it?

"Julian Fowler" wrote in message


An easy test is to try burning from the same source onto different
media and at different speeds - and see which sounds "best" on your CD
player.

There's also a somewhat more complex way in which you can
test whether the copy is, indeed, bit-identical to the original (a
necessary component of creating a "good" copy, but unfortunately not
sufficient - a copy that is identifical from the perspective of
computer processing may still produce a different sound through your
CDP)

To put this into perspective, a copy that is not bit-perfect under ideal
conditions can't reasonably be expected to play flawlessly on *any* CD
player. Therefore bit-perfect reproduction is necessary if the best sound
quality is desired.

When an audio CD player is having difficulty playing a CD-R the symptoms are
generally pretty clearly noticeable. The disc won't load, there will be tics
and pops, chunks of music will be missing, and eventually the disc might
even stop playing.

Virtually all problems that CD players have with playing CDs result in data
from the original recording being lost. These losses may be detected and
concealed by the means described in
http://www.cdrinfo.com/Sections/Arti...eadline=Writin
g+Quality&index=0
but the root problem is always data loss.

Data loss and attempts to conceal it can be perceived many ways, but in no
case is there actually any change to the general timbre of the music that
finally gets played.

Dave Plowman in uk.rec.audio:

In article ,
Stevie Boy wrote:
I've never myself (tad lazy in this respect) burned/copied a CD
however I do have the original and a copied version of the very same
CD. This was done by a friend at 32x on a Sony 32x writer and the
difference is shocking to say the least. The copy clearly has a much
brighter balance to it with treble emphasis.

Wonder if pre-emphasis and a faulty flag came into the equation
somewhere? I've burnt many CDs at all sorts of speeds, and found that
they either work or don't. But certainly never heard a difference in
the tonal balance - this just doesn't make sense with digits.


Only explanation I can think of is that the disc was copied on a cd-burner
seperate, using the analogue in/outputs.

--
Jim H
3.1415...4999999 and so on... Richard Feynman

Julian Fowler in uk.rec.audio:


(the differences in what constitutes a '0' and a '1' is much
less with a dye-based CD-R than with the physical geometry of a
pressed CD). It is possible, therefore, that the CD player is getting
more read errors and doing more interpolation with the CD-R than with
the original CD.

There are programs, such as ExactAudioCopy, that will check the duplicated
cd is a perfect copy. If a player can't read CD-R it is outside the redbook
standard and shouldn't be sold as a cd player.

But if you want to make really sure your CDP is up to reading CD-R, get one
that can understand CD-RW too.

An easy test is to try burning from the same source onto different
media and at different speeds - and see which sounds "best" on your CD
player. There's also a somewhat more complex way in which you can
test whether the copy is, indeed, bit-identical to the original (a
necessary component of creating a "good" copy, but unfortunately not
sufficient - a copy that is identifical from the perspective of
computer processing may still produce a different sound through your
CDP)

Again, if your CDP can't read CD-R it is faulty. If a £10 cd-rom drive
spinning at 30-50 times normal speed can read the bits without error, I'd
expect any audio CDP to read perfectly at the relatively slow redbook
speeds.

--
Jim H
3.1415...4999999 and so on... Richard Feynman

Stevie Boy wrote:

snip
- the dyes in
current CD-Rs actually work better at higher speeds than at low
(someone did a study on this a couple of years ago and published
results on the web).

Interesting I too would like some link on these results.


Some of the more modern burners are able to report error rates and
jitter on burned discs. I've been doing some informal error rate tests
on a Plextor Premium drive and I've noticed that, in general, older
drives have generally higher error rates but they aren't particularly
speed dependent (with the odd specific exception) unless burned at the
fastest possible speed. Burning at the absolute highest speed that the
burner/media combination will allow does seem to produce higher error
rates but these error rates on modern drives are still lower than those
achieved by older drives at low speeds.

Having said that there is no general rule, I typically burn at half of
the lower of burner speed and media rating - e.g., for a x32 disc on
an x48 burner burn at x16. On my setup this produces copies that (a)
are digitally identical to the original, and (b) play without any
discernable error or difference in sound on a variety of CD players.

Out of interest which manufacturer/s do you use for media and burners?


I use Plextor burners with Mitsui 16X or Taiyo Yuden media. The Mitsui
media generally gives the lowest error rates. Decent quality Mitsui
media appears to be no longer available though.

Cheers.

James.

- the dyes in
current CD-Rs actually work better at higher speeds than at low
(someone did a study on this a couple of years ago and published
results on the web).


Me just thinking over a few days... the above mentioned sentence seems a odd
thing to say.
Why would dyes be more penetrable ( It would seem that this is what one is
saying) at a higher revolution than normal?

Does something magical happen to the dye when it spins at high revolutions?

That said what is special about the dyes on them that allow the discs only
to be played at a max revolution?
And been looking for an answer for this for a while now... what is the
advantage/disadvantage of black CD-R's?

Steve

Dyes
also need the correct laser power for the right amount of time in order
to produce a correctly sized hole in the dye. Too little power and the
hole will not form while too much power will cause the hole to expand
too much and possibly interfere with adjacent tracks. Dyes intended for
use at high speeds will be more sensitive than those used at low speeds

Ok that makes sense but one thing still remains a doubt. If Hi-speed discs
perform optimally close to their stated speed then burning a disc at very
low speed in respect to its max speed would suggest some form of data error
in some way or even coasters as many would say.

And perhaps vice versa at its max speed.

Steve