[OT] CD-R masters, block error rate and dvd-r mystery...

[Joern Nettingsmeier]

hi everyone!


for the first time ever, i have to prepare a cd-r master that will go
into production without verification by the plant (yeah, i know, but my
client got a *really* cheap deal ;)

so i will have to make sure the data is ok and the block error rate is low.

* how do i measure BLER on CD-Rs with free software tools?

* how on earth can the same content burned via cdrdao to a CD-R on a
cdrw drive (Plextor) and a dvdrw drive (LG) differ in several hundred
thousand bytes when read back in with cdparanoia?

both drives seem ok, i frequently use them to burn data cds and dvds
which perform ok.

any hints welcome, tia,


jörn


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[Joern Nettingsmeier]

Jörn Nettingsmeier wrote:

> * how on earth can the same content burned via cdrdao to a CD-R on a
> cdrw drive (Plextor) and a dvdrw drive (LG) differ in several hundred
> thousand bytes when read back in with cdparanoia?

hmm. again, here's what i did:

i burned the same disk-at-once session four times, using the following
command:

cdrdao write /dev/<device> mytoc.toc

twice i wrote to /dev/cdrw, and twice to /dev/dvdrw.

all four disks were read back in using cdparanoia, to four different
directories: cdrw1, cdrw2, dvdr1, dvdr2.

when i cmp the files in cdrw[12], no diff.
when i cmp the files in dvdr[12], no diff.

when i cmp cdrwN to dvdrN, pooof! several thousand bytes differ.

wtf?????

please tell me it's really obvious and i'm doing something unspeakably
stupid.

regards,

jörn



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[hollunder]

On Wed, 23 Jul 2008 16:11:42 +0200
Jörn Nettingsmeier <nettings@...> wrote:

> hi everyone!
>
>
> for the first time ever, i have to prepare a cd-r master that will go
> into production without verification by the plant (yeah, i know, but
> my client got a *really* cheap deal ;)
>
> so i will have to make sure the data is ok and the block error rate
> is low.
>
> * how do i measure BLER on CD-Rs with free software tools?
>
> * how on earth can the same content burned via cdrdao to a CD-R on a
> cdrw drive (Plextor) and a dvdrw drive (LG) differ in several hundred
> thousand bytes when read back in with cdparanoia?
>
> both drives seem ok, i frequently use them to burn data cds and dvds
> which perform ok.
>
> any hints welcome, tia,
>
>
> jörn

Hi,
I know that there are some differenes with drives, and stuff like r/w
offsets and so on, but that sounds like a huge difference to me.
I don't know much about that stuff, but I know where to find
knowledgeable people.
I'd give the hydrogenaudio.org forums a shot. If the guys there can't
answer your questions, I don't know who can.
Note that the forums focus is not on free software but on audio codecs,
cd ripping and foobar2k. I hope that they can help you anyway.

Oh, and if you find something interesting, please consider sharing it
with us.

Best Regards,
        Philipp
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[Fons Adriaensen-2]

On Wed, Jul 23, 2008 at 04:18:57PM +0200, Joern Nettingsmeier wrote:

> when i cmp cdrwN to dvdrN, pooof! several thousand bytes differ.

Any obvious pattern in the differences and/or their position ?

--
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

O tu, che porte, correndo si ?
E guerra e morte !



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[Joern Nettingsmeier]

hi anthony!

thanks for your reply. i'm cc:ing the list so that others can benefit
from it as well...

Anthony Kozar wrote:

> Hi Joern,
>
> This is just a shot in the dark, but most audio CD tracks have a "lead-in"
> time of 2 or more seconds.  CD players will typically count down using
> negative numbers for this time and the track is considered to begin after
> the lead-in.  Perhaps one of your drives (the DVD drive?) is reading the
> lead-in as part of the track?
>
> (2 seconds x 44100 samples/sec. x 2 channels x 2 bytes/sample = 352,000
> bytes)

i can rule this out, because although i used both a dvdr and cdr drive
for burning, both cds were read back in using the cdr drive.

any differences must have occured during burning. but since i used the
same toc file and disk-at-once mode, it's unlikely that the lead-in got
interpreted differently in both drives... but you are right, this being
a live cd, i used pre-gaps and non-silent gaps extensively - i'll
investigate some more along those lines.

best,

jörn



--
jörn nettingsmeier

home://germany/45128 essen/lortzingstr. 11/
http://spunk.dnsalias.org
phone://+49/201/491621

Kurt is up in Heaven now.
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[Eric Shattow]

To get a more accurate idea of block errors, use a quality drive like a Plextor and Robert Fuller's https://gna.org/projects/cued software. My Plextor 712-SA does the trick. Be aware that the firmware of Plextor drives does some error correction to achieve the extremely low jitter.

HA forums are awash with positive remarks about EAC (Exact Audio Copy on Windows OS) being the best software, but it's unmaintained and does not do a very good job of ripping CD audio.

Also, there is no fully capable software to rip/write CD media on a modern *nix OS in raw96 mode. Without this mode, you don't have any way of knowing what errors are actually existent on the media being produced (or read). Most drives cook the error correction in various ways when ripping in other modes. The official specifications for CD media formats are costly and not easy to obtain.

What kind of deal does your friend get, that is worth all this trouble?

On Wed, Jul 23, 2008 at 3:06 PM, Joern Nettingsmeier <nettings@...> wrote:

hi anthony!

thanks for your reply. i'm cc:ing the list so that others can benefit
from it as well...

Anthony Kozar wrote:
> Hi Joern,
>
> This is just a shot in the dark, but most audio CD tracks have a "lead-in"
> time of 2 or more seconds.  CD players will typically count down using
> negative numbers for this time and the track is considered to begin after
> the lead-in.  Perhaps one of your drives (the DVD drive?) is reading the
> lead-in as part of the track?
>
> (2 seconds x 44100 samples/sec. x 2 channels x 2 bytes/sample = 352,000
> bytes)

i can rule this out, because although i used both a dvdr and cdr drive
for burning, both cds were read back in using the cdr drive.

any differences must have occured during burning. but since i used the
same toc file and disk-at-once mode, it's unlikely that the lead-in got
interpreted differently in both drives... but you are right, this being
a live cd, i used pre-gaps and non-silent gaps extensively - i'll
investigate some more along those lines.

best,

jörn



--
jörn nettingsmeier

home://germany/45128 essen/lortzingstr. 11/
http://spunk.dnsalias.org
phone://+49/201/491621

Kurt is up in Heaven now.
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[hollunder]

On Sat, 26 Jul 2008 17:39:12 -0500
"Eric Shattow" <lucent@...> wrote:

> To get a more accurate idea of block errors, use a quality drive like
> a Plextor and Robert Fuller's https://gna.org/projects/cued software.
> My Plextor 712-SA does the trick. Be aware that the firmware of
> Plextor drives does some error correction to achieve the extremely
> low jitter.
>
> HA forums are awash with positive remarks about EAC (Exact Audio Copy
> on Windows OS) being the best software, but it's unmaintained and
> does not do a very good job of ripping CD audio.
>
> Also, there is no fully capable software to rip/write CD media on a
> modern *nix OS in raw96 mode. Without this mode, you don't have any
> way of knowing what errors are actually existent on the media being
> produced (or read). Most drives cook the error correction in various
> ways when ripping in other modes. The official specifications for CD
> media formats are costly and not easy to obtain.
>
> What kind of deal does your friend get, that is worth all this
> trouble?

Uh, that app is new to me, up until now I thought that rubyripper is
the best choice on linux. I haven't tried this one or rubyripper in a
while tough, may both be worth a try.

At the HA forums is a lot of talk about EAC, yes, but afaik these days
people there tend to use the commercial dbpoweramp. I think that it's
considered better than EAC. Correct me if I'm wrong, but I don't know
of other serious choices for windows.

Also, the often used as secure-ripper-on-linux-backend cdparanoia is
spoken of nicely.
It's news to me that libcdio is capable of bearing better results.
I really like to hear more about capable tools for linux.

Best Regards,
        Philipp
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