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EAC... how perfect? How does it work?, Redundant, but more detailed questions
Radetzky
post Mar 10 2003, 01:55
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I've been reading HydrogenAudio for a couple of weeks now and think
this place is a real gem for audio nuts. wink.gif

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? smile.gif

Thanks for your time and patience ! :-)
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Mr. Mulder
post Mar 10 2003, 09:00
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The ETA for the next version of EAC is the same as Duke Nukem Forever; "When it's done". tongue.gif


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Pio2001
post Mar 10 2003, 13:21
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Interesting questions indeed B)

[quote=Radetzky,Mar 10 2003 - 03:55 AM]1. Is it true that (at minimum) in any of the Secure modes EAC will  read at least twice every thing it reads?  [/quote]
No !
[quote=Radetzky,Mar 10 2003 - 03:55 AM]When, if ever, does EAC perform only one read of the audio?[/quote]
As soon as you check the "drive is capable of C2" checkbox. And also if the drive caches and the "drive caches" checkbox is disabled. Note that some drives (I can remember two posts) are reported to cache by Feurio and not by EAC, which would lead the drive not to read twice even with EAC properly configured (according to its own feature detection i.e. no cache).
[quote=Radetzky,Mar 10 2003 - 03:55 AM]How big is the chunk of data that
   is being read?  10x2352 bytes?  2352 bytes?  1 bit?[/quote]
27 sectors = 63,504 bytes for error detection, then less for error correction, according to the size of the error detected, when the red lights turn on.
[quote=Radetzky,Mar 10 2003 - 03:55 AM]How sure can we be that EAC
   really does detect and "correct" errors?[/quote]
It depends on the drive for the C2 mode. 99 % seems an average value. But it varies from zero to 100 %. The reading twice mode (no C2) is more secure, so it can be trusted more than 99.9 % (that is the C2 accuracy of my Teac drive). Test and copy is even more secure : it can detect errors unnoticed in secure mode, non accurate, cache, no C2 mode.

http://www.cdrinfo.com performs C2 accuracy tests (available for recent reviews only).
My own C2 accuracy tests : http://perso.numericable.fr/~laguill2/dae/dae.htm
[quote=Radetzky,Mar 10 2003 - 03:55 AM]the returned data is, say 0x2431. It reads again and the data is still 0x2431.  [...]  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?[/quote]
It is very rare that a scratch turns wrong just one byte. Such cases have been reported by BobHere ( http://www.digital-inn.de/showthread.php?t...?threadid=16578 ) and someone here (Tigre or Halcyon, I think), among about 1000 CDs ripped, IIRC.
Most of the time, a scratch turns wrong several tens of bytes (see the increments of errors in Nero CD Speed quality check). When the reading is done again, some bytes that were wrong are right, and some that were right are wrong, and the difference is detected : http://www.digital-inn.de/showthread.php?t...?threadid=15838
[quote=Radetzky,Mar 10 2003 - 03:55 AM]how sure are we
   of that?[/quote]
I'd say that the superiority of reading twice vs C2 has been tested about half a dozen times, and reading twice always came better than C2, that must have been at 99% accuracy. But remember it's before all a matter of drive, and of caching.
[quote=Radetzky,Mar 10 2003 - 03:55 AM]should I go nuts with the
   offsets?[/quote]
No
[quote=Radetzky,Mar 10 2003 - 03:55 AM]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)?  [/quote]
Perfectly right, glad to see someone at last, who understands that offset correction has nothing to do with secureness smile.gif
[quote=Radetzky,Mar 10 2003 - 03:55 AM]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?[/quote]
Yes, CIRC (error correction for compact disc) is performed by the drive, otherwise the audio couldn't even be decrypted.
But the exact error correction algorithms used can vary. I saw different ones used by different drives : http://perso.numericable.fr/~laguill2/dae/...set/chipset.htm
In fact, the drive switches between different error correction strategies so as to optimize error correction according to the state of the CD : http://www.digital-inn.de/showthread.php?t...18281#post59836
[quote=Radetzky,Mar 10 2003 - 03:55 AM]In DAE mode (... is it a 'mode' ?)[/quote]
Yes : http://forum.cdfreaks.com/showthread.php?s...&threadid=47958
[quote=Radetzky,Mar 10 2003 - 03:55 AM]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?[/quote]
My drives all interpolate : http://perso.numericable.fr/~laguill2/dae/...terpolation.htm . I think older CD ROM drive didn't interpolate, I remember my Artec 34x returning standalone spikes in damaged aeras of some CDs, that don't appear in my current drives. I think it didn't interpolate and returned uncorrected data.
[quote=Radetzky,Mar 10 2003 - 03:55 AM]Asked differently, in DAE mode does the drive treat the audio data as audio or as data?[/quote]
Processing data is using the third level of error correction present on CD ROMs. Audio can't be treated as data because this extra error correction codes are not on the CD.
[quote=Radetzky,Mar 10 2003 - 03:55 AM]The actual CD might have errors
injected during its pressing (!).[/quote]
CIRC should deal with errors injected during the pressing the same way that it deals with errors produced during the playback.
[quote=Radetzky,Mar 10 2003 - 03:55 AM]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?[/quote]
No, the quality directly depends on the drive.
The secureness, on the other hand, is the same in test and copy, or non accurate, cache, no C2 mode. Some rare drives (Yamaha CRW6416 is a good example) have not accurate stream, the others will all be equally secure in cache/No C2 mode. Many drives can be unsecure in no cache mode. All drives seem to perform differently in C2 mode.

Edit : added the order of magnitude of the amount of CDs ripped by BobHere to find wrong CRC matching, updated links, put back interpolation pictures online
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tigre
post Mar 10 2003, 14:49
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Great answer, Pio2001 - You should add this thread to the FAQ. smile.gif


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AtaqueEG
post Mar 10 2003, 18:40
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QUOTE (tigre @ Mar 10 2003 - 09:49 AM)
Great answer, Pio2001 - You should add this thread to the FAQ.  smile.gif

I think my response should be erased first.
Seems I got it all wrong! ohmy.gif


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NumLOCK
post Mar 10 2003, 19:16
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QUOTE (Pio2001 @ Mar 10 2003 - 01:21 PM)
It is very rare that a scratch turns wrong just one byte. Such cases have been reported by BobHere ( http://www.digital-inn.de/showthread.php?t...?threadid=16578 ) and someone here (Tigre or Halcyon, I think).
Most of the time, a scratch turns wrong several tens of bytes (see the increments of errors in Nero CD Speed quality check). When the reading is done again, some bytes that were wrong are right, and some that were right are wrong, and the difference is detected : http://www.digital-inn.de/showthread.php?t...?threadid=15838
QUOTE (Radetzky @ Mar 10 2003 - 03:55 AM)
how sure are we
   of that?

I'd say that the superiority of reading twice vs C2 has been tested about half a dozen times, and reading twice always came better than C2, that must have been at 99% accuracy. But remember it's before all a matter of drive, and of caching.

Very good point.

I personally would go with Secure, Test & Copy, C2 Enabled. This way, everything will be verified with CIRC *and* read twice (just in case..)

If someone finds any weakness in this approach, I'd be happy to hear it.

Happy ripping wink.gif


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BadReligionPR
post Mar 10 2003, 19:58
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QUOTE (NumLOCK @ Mar 10 2003 - 10:16 AM)
I personally would go with Secure, Test & Copy, C2 Enabled.  This way, everything will be verified with CIRC *and* read twice (just in case..)

If someone finds any weakness in this approach, I'd be happy to hear it.

Didn't Pio2001 just say that by enabling C2, it no longer reads twice but instead uses C2 error detection to find errors, thus making it less secure?

QUOTE
QUOTE (Radetzky @ Mar 10 2003 - 03:55 AM)
When, if ever, does EAC perform only one read of the audio?

As soon as you check the "drive is capable of C2" checkbox
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ben
post Mar 10 2003, 21:52
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QUOTE (Pio2001 @ Mar 10 2003 - 12:21 PM)
No, the quality directly depends on the drive.

What do you mean by quality? Quality as in the # of errors picked/not picked up? Or quality as in how it sounds(too bright, no bass, etc).. I'm guessing you mean the former..
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Pio2001
post Mar 10 2003, 22:25
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QUOTE (NumLOCK @ Mar 10 2003 - 09:16 PM)
I personally would go with Secure, Test & Copy, C2 Enabled. 
(...)
If someone finds any weakness in this approach, I'd be happy to hear it.

Good approach. It's my default setting. The only weak point I can see is marginal : trying to recover damaged CDs, when error correction fails, but not by far, test and copy burst mode at low speed gives me the best results (same CRC), because in burst mode there is no risk of sync errors when the drives seeks back in order to try to correct errors.
QUOTE (BadReligionPR @ Mar 10 2003 - 09:58 PM)
Didn't Pio2001 just say that by enabling C2, it no longer reads twice but instead uses C2 error detection to find errors, thus making it less secure?

Doing a "Test and copy" is reading twice. Thus test and copy with C2 on is both reading twice and using C2.
QUOTE (ben @ Mar 10 2003 - 11:52 PM)
What do you mean by quality?  Quality as in the # of errors picked/not picked up?  Or quality as in how it sounds(too bright, no bass, etc)..

None of them, I meant the ability to read damaged CDs without any read error, detected or not.
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Pio2001
post Mar 10 2003, 22:30
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QUOTE (AtaqueEG @ Mar 10 2003 - 08:40 PM)
Seems I got it all wrong!  ohmy.gif

Thank you nonetheless for taking the time to try to help ! It is appreciated.
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Radetzky
post Mar 11 2003, 04:06
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Thanks Pio2001. Your answers sure shed light on my concerns. wink.gif

Though (damn it.. there's always one more thing to ask it seems smile.gif,
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?

------------------------------------------------------------------------

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 wink.gif : 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?

------------------------------------------------------------------------

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
smile.gif
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Mr. Mulder
post Mar 11 2003, 07:42
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QUOTE (Pio2001 @ Mar 10 2003 - 06:25 PM)
[]trying to recover damaged CDs, when error correction fails, but not by far, test and copy burst mode at low speed gives me the best results (same CRC), because in burst mode there is no risk of sync errors when the drives seeks back in order to try to correct errors.[]

I hope you can clear a doubt I've been having, Pio2001. smile.gif
"Burst mode" it's better with scratched CDs, but i've been trying also with the synchronized "Fast Mode" in EAC to try to copy damaged CDs; will "Burst Mode" will be better than "Fast Mode" in any case, or also depends on the drive?


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tigre
post Mar 11 2003, 09:06
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QUOTE (Radetzky @ Mar 10 2003 - 07:06 PM)
Finally, EAC detects the following fatures 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?

Exactly. Otherwise (cache off, but drive caches) on damaged positions where reading twice would result in different values, reading twice from cache results in identical values.

QUOTE
Would there be bad side effect of that?

More work for the drive('s mechanic components) resulting in longer extraction time and maybe the drive dying earlier.


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tigre
post Mar 11 2003, 09:57
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QUOTE (Mr. Mulder @ Mar 10 2003 - 10:42 PM)
"Burst mode" it's better with scratched CDs, but i've been trying also with the synchronized "Fast Mode" in EAC to try to copy damaged CDs; will "Burst Mode" will be better than "Fast Mode" in any case, or also depends on the drive?

From here:
QUOTE (Pio2001 @ Oct 24 2002 - 02:33 AM)
QUOTE (Joe Bloggs @ Oct 24 2002 - 07:27 AM)
Why is it that Burst mode is regarded as better than Fast mode? (IIRC)

Because it reads without repositioning the head, that increases the risk of loosing the track when there are scratches.


BTW: Here's another interesting EAC thread, among others about burst mode Test & Copy vs. Secure mode.


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Mr. Mulder
post Mar 11 2003, 12:00
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Thanks tigre. smile.gif


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Patsoe
post Mar 11 2003, 13:14
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QUOTE (Radetzky @ Mar 11 2003 - 04:06 AM)
But if the drive always provide the same value
from it's interpolation technique... we have a problem, no?

Yes and no. Yes, because you will not have read the right value at that position. No, because the drive can't do any better so interpolation is the best option available.
If C2 reporting by the drive is done properly, though, EAC will still be able to suspect that interpolation has been done at that position.
QUOTE
I saw _ben_ questionned the term 'quality'.  I too have a
problem understanding what you mean (even with the explanation you
gave him)...
....................will I have the _exact_ same .wav file on my
hdd (not taking into account the potentiel different offsets) ?

"Quality" concerns the whole drive. That is, e.g. a better laser pickup will read flawlessly where other drives would be needing interpolating, and so on. On a bad CD, with difficult positions, EAC-rips can thus be different with different drives.

Ofcourse, if there are such positions, you want to know.

My method is to use a drive with good C2 report. Then, rip in secure mode with C2 setting enabled, no cacheflushing, and offset correction, and do test+copy. Then, if there are C2 errors you'll have a less than 100% track quality, so even if test and copy CRCs match, you'll know there is a possibly interpolated position.

If this occurs, take a second drive: different brand, different chips. (this is why you need offset correction; to compare with the second drive). If it returns the same rip CRC, all is fine. Else, since interpolation values of different drives will probably be slightly different, you can see the problem spot from wav-compare.

Why do I set no-cache mode? Because in my experience, less read errors occur with that setting; EAC doesn't flush the cache every 2MBs, and the pickup thus does less work. Ofcourse, this setting makes error correction by EAC useless (because re-reads will come from cache). But that's why you do test+copy. And besides, I don't want error-correction the EAC-way if not necessary. I just want to know if there's a troublesome scratch and if there is, I'll get another disc to rip from...

Edit: tried to make last paragraph more readable.

This post has been edited by Patsoe: Mar 11 2003, 13:32
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Pio2001
post Mar 11 2003, 13:33
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QUOTE (Radetzky @ Mar 11 2003 - 06:06 AM)
EAC will have received 12, 13, 15 both times but it will be from
an interpolated value.


Right.

QUOTE (Radetzky @ Mar 11 2003 - 06:06 AM)
if the drive always provide the same value
from it's interpolation technique... we have a problem, no?

if I extract a track with a
cheap drive and the same track with the best DAE capable drive and
EAC reports that the extraction went by without any error, will I have the _exact_ same .wav file on my
hdd ?


When I asked this very question in the EAC forum ( http://www.digital-inn.de/showthread.php?t...?threadid=15838 ), Andre didn't seem to understand what the hell I meant by "returning the erroneous value unchanged". For him, a wrong value, interpolated or muted, was always the same when reread.
Anyway, when I got my drives (Teac e540, Sony DDU1621, Memorex DVDMaxx1648) that all interpolate, thus return always the same value when an error occurs, I tested them in secure mode (I lost the logs), and saw, for at least one of them, but I think it was for the three of them, that reading twice, on CD with lots of errors, but all correctable, could sometimes return same CRC where C2 could not.
But it might have been twice the same wrong CRC. Here, all we can rely on is the reports about same wrong CRC, that occur much less than different CRC with no errors occured in C2 mode. See my first post.
Note that a different CRC with no errors occured is nothing more than different matching CRC for a tiny bit of track (the zone that was wrongly corrected).

QUOTE (Radetzky @ Mar 11 2003 - 06:06 AM)
When you talked about the 'quality', you were referring to the way the
drive interpolates between points if an error is detected?


Not at all

QUOTE (Radetzky @ Mar 11 2003 - 06:06 AM)
If not, what did you mean


Bad drive :
Millions of errors detected, barely 10 % of them correctable, speed falls to 0x.

Good drive :
Same CD, 32x secure mode, no error detected, quality 100%, CRC OK.

QUOTE (Radetzky @ Mar 11 2003 - 06:06 AM)
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?

This is not what I meant, this question is entierly about the secure mode performance as discussed previously (C2 accuracy, possibility of having wrong matching CRCs...)

QUOTE (Mr. Mulder @ Mar 11 2003 - 09:42 AM)
will "Burst Mode" will be better than "Fast Mode" in any case, or also depends on the drive?


We must test.

And for interesting threads about secure mode, don't forget to browse the secure mode section of the HydrogenAudio FAQ
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EmDub
post Mar 11 2003, 17:02
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QUOTE
Finally, EAC detects the following features for my drive : 'acurate
stream', 'no caching', 'no C2'.


I have this exact same drive (HL-DT-ST RW/DVD GCC-4240N), and I'm finally glad to see somebody else that does, too. Mine is in a Dell Latitude C640, so I know that it's not exactly a rarely used drive.

I also received the "accurate stream, no caching, no C2" results when testing with EAC. I've tried extracting with caching turned off and on, and I'm not sure what the difference is. My assumption was that if you always received a 100% score with caching turned off, then your drive probably really caches. Because it would obviously re-read the first results when trying to read the second time. Well, I get a range of scores--97% to 100%, so I'm assuming that this drive really does *not* cache. But I don't understand the process enough to guarantee that result. If somebody could shed some light on this, I would be most appreciative.

Also, what read offset correction did you get? I got +102, and I'm pretty sure it's correct. It's only based on using one CD from the reference list, but this CD (Beatles' Abbey Road) is one that gave me the correct result (based on the user database) on my HP 9100 CD-RW.

As for a write offset, I don't even know if it's capable of writing.

I'm also an "anal" type of person when it comes to things like this--I want to get it set up correctly once, and then just be able to use it. So I'm most interested in this thread.

Michael

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Radetzky
post Mar 12 2003, 02:17
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Pio2001:

Hmm.. so to my question "if I rip a track with a cheap drive and then
with _the_ perfect drive and on both occasions the rip is successful,
does it mean I have the same exact .wav file" you reply that
_theoretically_ it is not necessarely the case because EAC could be
fooled with 2 consecutive exact wrong reads.

But, if the CRCs match between the two drives, the probability that
the rip is correct must be growing a lot, no?

Also, normally, if the drive has to interpolate or mute, I believe an
error should be detected by EAC. Unless we are very unlucky and a
defect on the disc generates the same value twice. Is that right?

Anyway.. to make it short, if we get a successful rip with EAC,
it means we were able to extract the track ***perfectly***
99.999999999% of the time (0.0000000001% of the time a defect will
return the same value twice). J'ai bien compris? (by "perfect", I mean
a rip with all the useful musical data exactly as present on the disc, not
caring about the offsetted portion at the beginning and end)

EmDub:

I have a Dell Optiplex GX260. EAC detected 'accurate stream', 'no
caching' and 'no C2'. I tried it with many different CDs. I rip at
around 4, 5x most of the time. I never had an error. I *think* this
drive produces perfect rips.

I didn't care about the offsets. Use an offset of -10000 and then of
10000 and then load the .wav file in any decent wav editor. A total
delta of 0.04 second? I don't care! I am very anal about my music,
but there is a limit to 'analyness'. smile.gif
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Patsoe
post Mar 12 2003, 10:51
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Radetzky: you're somewhat repeating your same question smile.gif

to summarize what I tried to say earlier:
* A drive that interpolates without reporting C2 errors may fool EAC into thinking there have been two good reads.
* Do use offset correction: otherwise you cannot compare CRCs between two drives. Ripping and comparing with two different drives should be very secure.
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Pio2001
post Mar 12 2003, 12:43
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QUOTE (Radetzky @ Mar 12 2003 - 04:17 AM)
Also, normally, if the drive has to interpolate or mute, I believe an
error should be detected by EAC.  Unless we are very unlucky and a
defect on the disc generates the same value twice.


QUOTE (Patsoe @ Mar 12 2003 - 12:51 PM)
* A drive that interpolates without reporting C2 errors may fool EAC into thinking there have been two good reads.


QUOTE (Radetzky @ Mar 12 2003 - 04:17 AM)
if we get a successful rip with EAC,
it means we were able to extract the track ***perfectly***
99.999999999% of the time


Seems rather

C2 on :
Perfect CD : probability to get a perfect rip when EAC says so equals the C2 accuracy measured by CDRinfo tests, or by yourself with the DAEquality kit.
Bad CD : 50 % (very often I have CRC mismatch for CDs with a lot of error correction, but all errors corrected, on a 99% C2 accurate drive)

C2 off
99,9 % according to BobHere reports about same wrong CRC (order of magnitude : one out of 1000 CDs)

QUOTE (Radetzky @ Mar 12 2003 - 04:17 AM)
if the CRCs match between the two drives, the probability that
the rip is correct must be growing a lot, no?


Not necessarily, if the defect depends only on the CD. We have no test results about this.
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yourtallness
post Mar 12 2003, 13:27
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QUOTE
What do you mean by quality? Quality as in the # of errors picked/not picked up? Or quality as in how it sounds(too bright, no bass, etc).. I'm guessing you mean the former..


Can a badly extracted wav lack in bass, pitch, etc. ?

I mean, an audio CD is full of 1's and 0's, so if the extracted wav has some 1's or 0's wrong
it should have clicks or pops or not? It's not vinyl where a slightly deeper groove could produce
slightly different sound... Am I wrong?


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Patsoe
post Mar 12 2003, 13:48
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QUOTE (yourtallness @ Mar 12 2003 - 01:27 PM)
Can a badly extracted wav lack in bass, pitch, etc. ?

I mean, an audio CD is full of 1's and 0's, so if the extracted wav has some 1's or 0's wrong
it should have clicks or pops or not? It's not vinyl where a slightly deeper groove could produce
slightly different sound... Am I wrong?

If interpolation is performed well, there may not be pops/clicks. However, there will be lack of precision, whatever that sounds like.

Thus, a good drive, i.e. one with a good pickup which needs little error correction, is a starting point for high quality DAE.
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yourtallness
post Mar 12 2003, 14:04
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Let me rephrase: in digital audio, a 1 that should be a 0 can result in
entirely different sound, or not? I can't see how errors could add/remove
bass, depth etc. from a song...


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KikeG
post Mar 12 2003, 14:40
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I doubt error interpolation can result in less bass or something similar. What could be the result of lots of interpolation: maybe things like lack of definition, distortion, small artifacts... (just wondering)...
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