EAC... how perfect? How does it work?, Redundant, but more detailed questions Options

[Radetzky]

I've been reading HydrogenAudio for a couple of weeks now and think
this place is a real gem for audio nuts.

I am about ready to proceed to backup about 250 CDs of mine on a
RAID-1 setup. I plan to rip all the CDs using a LGE HL-DT-ST RW/DVD
GCC-4240N drive and EAC 0.9b4.

Though, before doing do, I would love to have your input regarding a
couple of points I have a hard time with. I hope you won't find these
questions redundant. I know some, or most, have already been asked
but I never was satisfied with the answers (*not* that I think anybody
_has_ to provide an answer I will be happy with...).

So here goes for the questions :

1. Is it true that (at minimum) in any of the Secure modes EAC will
read at least twice every thing it reads? I ask so because there
are no confirmation anywhere in the software that it is doing so.
It would be nice if during the rip process a little string saying
"currently reading each sector twice" or something would appear.

When, if ever, does EAC perform only one read of the audio?

2. Exactly what does it read twice? How big is the chunk of data that
is being read? 10x2352 bytes? 2352 bytes? 1 bit?

3. I know this has already been asked at digital-inn.de, but I don't
think I understood the answer fully. How sure can we be that EAC
really does detect and "correct" errors?

I mean, lets say there is a minor scratch on one of my CDs. My
drive reads through the scratch.. the returned data is, say 0x2431.
It reads again and the data is still 0x2431. EAC thinks this is
fine. But the scratch is done in such a way that the reflected
information is always the same, AND wrong. How could EAC deal with
this physical anomaly?

I remember Andre (the author of EAC) said something like it was
very unlikely that the same data could be read from a scratch or
spot (or whatever damage there is) on the CD. But how sure are we
of that?

4. If I intend to keep all the ripped music on my computer and not
duplicate it on, say, CD-R media, should I go nuts with the
offsets?

I did tests myself and I tried to inject a -10000 offset and then a
+10000 offset and it didn't mater at all sound wise. I checked
with a WAV editor (Audacity) and the difference (the time-offset)
was really minimal and only cutting or adding silence (haven't
found a CD that starts with music too soon).

If I want to extract all the tracks as one big WAV file, am I right
to say that the digital extraction is successful anyway, that the
offset only induces a time-shift (a very, very small one)? Or is
there a subtlety I didn't grasp?

5. A very important (to me) question. When EAC commands the drive to
read whatever amount it has to during its rip process, what error
correction is performed by the drive? Is it using the Reed Salomon
ECC error codes from the disc?

In DAE mode (... is it a 'mode' ?), if the drive detects a problem
on the disc (scratch, etc.) will it try to interpolate between two
points or will it just send the data back unmodified?

Asked differently, in DAE mode does the drive treat the audio data
as audio or as data?

Reading http://www.roxio.com/en/support/cdr/cderrors.html leads one
to believe there are many more problems to deal with that "only"
scratches and finger prints. The actual CD might have errors
injected during its pressing (!).

6. I have a HL-DT-ST RW/DVD GCC-4240N drive. It is a low-profile
combo (DVD + CD-RW) drive. When I perform a rip using EAC and this
drive, will it be of the same quality from a rip performed from,
say, a Plextor Ultraplex drive?

7. Last question... what is the ETA for the next release of EAC?

Thanks for your time and patience ! :-)

[Radetzky]

Thanks Pio2001. Your answers sure shed light on my concerns.

Though (damn it.. there's always one more thing to ask it seems ,
you are saying that if a problem is detected, the drive will
interpolate.

What if three points are read (oversimplication here) and the values
are :

12 83 15

The drive knows the value 83 is in error an interpolates a 13 between
the 12 and the 15. Now, EAC asks for another read to the drive and
now the values are :

12 -123 15.

The drive, again, detects the problem and, again, interpolates to a
13. EAC will have received 12, 13, 15 both times but it will be from
an interpolated value.

Is this oversimplication wrong?

I understand that 27 sectors are read and that the probability of the
27 sectors to be okay on a second read if a physical damage is present
on the disc is low. But if the drive always provide the same value
from it's interpolation technique... we have a problem, no?

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Also, I saw _ben_ questionned the term 'quality'. I too have a
problem understanding what you mean (even with the explanation you
gave him)...

I will formulate the original question differently (or this is going
to be a new question, I don't know : if I extract a track with a
cheap drive and the same track with the best DAE capable drive (let's
say the Plextor's are the best for the sake of this discussion) and
EAC reports that the extraction went by without any error (regardless
of the 'track quality'), will I have the _exact_ same .wav file on my
hdd (not taking into account the potentiel different offsets) ?

When you talked about the 'quality', you were referring to the way the
drive interpolates between points if an error is detected? For
example, a Plextor could use splines instead of a linear
approximation. Was that what you meant?

If not, what did you mean, and how would the sucessfully reported
extraction from EAC differ when it is performed from a el-cheapo CD-ROM
drive from a top of the line, made for DAE, CD-ROM drive?

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Finally, EAC detects the following features for my drive : 'acurate
stream', 'no caching', 'no C2'.

If I select 'Drive caches audio data' anyway, will it force EAC to
flush the inexistant cache and demand a second read _just in case_
there really is a cache and EAC couldn't detect it? Would there be a
bad side effect of that?

Again, thanks for your time.. thanks for calming a way too anal person