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Scratched CDs and Eac settings
bwssouth
post Dec 21 2013, 18:44
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I have a scratched CD and when ripping it using EAC (flac), sometimes EAC says that there is an error and sometimes EAC says that no errors have occured.

Is it possible that sometimes EAC is able to read the scratched CD accurately and sometimes don't? -- or is it just that EAC sometimes isn't attentive enough?
Would you consider this cd an accurate rip, if sometimes it says that is error free?

Is it worth trying to rip scratched CDs more times?

Also I would like to ask you something about EAC settings.

Under drive options, I have chosen secure mode and under it, I ticked only Drive has accurate stream feature.

But other two options: chace and retiving C2 are not ticked. Probably my drive is able to use C2 but I unticked it, because it was said that C2 isn't a good option.

Do you suggest me to tick C2 too?
My driver doesn't support chace-- is this a problem when talking about quality?


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Zarggg
post Dec 21 2013, 20:56
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A good place to start would be to make sure your settings are at a recognized baseline, such as the setup recommended by the EAC Lossless Backup guide. (Additional details about the Drive Settings can be found in the EAC Drive Options article.)

In the most basic of terms, when Secure Mode comes across a read error, it will try to re-read that sector on the disc several times to try to get consistent data. Whether it does or does not, it moves on once that number of tries specified have been exhausted.

"Quality" isn't really a concern so much as data consistency. If you're using AccurateRip in EAC as your comparison, my experience has been that you can essentially trust whether the report says whether your rip was accurate according to their database. If EAC can't read consistent data, then they won't match up.

The music itself may or may not sound "right" to you in the end, but that's a risk taken when trying to read a damaged/scratched disc. I've ripped several of my old, scratched CDs with EAC in the past and found that some of them that reported an AccurateRip mismatch still sounded fine with no or very limited skipping/glitching/etc.

In my opinion, If you're using standard settings, one rip should be enough, because the odds of getting it (more) right after additional tries aren't significant enough to spend time on.

This post has been edited by Zarggg: Dec 21 2013, 20:59
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bwssouth
post Dec 21 2013, 21:11
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Why accurate rip doesn't ask me anymore about settings, when starting eac?

Sorry to ask, but is there any difference if you choose just copy selected tracks instead of test and copy selected tracks?

By default, detection accuracy is set to inaccurate. What is the difference between secure and inaccurate? Does this accuracy settings (gaps) only affect cue settings or does it affect quality? - how to see if gap detection was ok (when using inaccurate)?

This post has been edited by bwssouth: Dec 21 2013, 22:04
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greynol
post Dec 21 2013, 21:32
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QUOTE (Zarggg @ Dec 21 2013, 11:56) *
If EAC can't read consistent data, then they won't match up.

Even if EAC can read consistent data it may not match up. Consistent is not synonymous with accurate (nor is it synonymous with error-free).

Furthermore, it is possible for EAC to get error-free data during a subsequent read but not use this data because specific errant data is more consistent.

This post has been edited by greynol: Dec 21 2013, 23:47


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mjb2006
post Dec 22 2013, 03:06
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QUOTE (bwssouth @ Dec 21 2013, 14:11) *
Why accurate rip doesn't ask me anymore about settings, when starting eac?

Your drive's read offset doesn't change. Once known, there's nothing else to configure.

QUOTE
is there any difference if you choose just copy selected tracks instead of test and copy selected tracks?

If you choose to do a test pass, it is like doing a whole 'nother rip, wearing out your drive, just to get checksums to compare the real rip against. You should only need to do this if you're not getting trustworthy matches from AccurateRip.

QUOTE
By default, detection accuracy is set to inaccurate. What is the difference between secure and inaccurate?

Much like the difference between gap detection methods A, B, C ... no one knows. The developer doesn't say much, and the code is not open-source.

QUOTE
Does this accuracy settings (gaps) only affect cue settings or does it affect quality? - how to see if gap detection was ok (when using inaccurate)?

Nothing to do with quality. The accuracy & method settings only affect the INDEX 00 values in the cue sheet. These values are telling a CD burner what portion of the track is designated as a section where a real CD player's display should advance the track# and count up from a negative timecode to 0:00. Generally this corresponds to pauses or interludes in the music. Ideally, you want to get correct values from the disc's subcode, but subcode is often hard to read. Even when it's easy to read, it's common for index/gap boundaries to vary by a small amount each time. I don't know why.

If gap detection is very slow or is producing absurdly large or tiny values, try different settings. I generally don't worry about it, though, because no one really wants a perfect copy of anything but the audio data. Subcode perfection is hard to attain, and rippers don't even log what subcode reading they attempted.
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