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Topic: A few questions about C2 (Read 3417 times) previous topic - next topic
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A few questions about C2

I've been reading things about DAEQuality tests and stuff, and I've got to say that it confuses me a hell of a lot:

In EAC 0.9b4 there was an option called "Use C2 error information for error correction". Does that mean it tries to correct uncorrectable E32/E42 (or something like that) errors with the drive's C2 routines? So that one's absolutely forbidden AFAIK.

What if only "Drive is capable of retrieving C2 error information" is checked? Does that only use the drive's C2 for correctable E12/E22 errors?

I don't understand why this lighter way of C2 correction is so plagued. I've ripped a few dozens of CD's, including scratched library CD's and in fact, I remember only 2 cases where C2 failed me.

1. Extraction of a fairly new CD with quite few and light scratches. My Sony DDU-1621(S1e7 FW) detected a nonexistant error and wasn't capable of continuing. Without C2 and with my LG GCE-8320B's (1.04) C2 it went totally without problems, resulting in same CRC values.

2. A very minor click at the end of one track (LG rip). Looks like my Sony's C2 was better that time (which is usually quite rare).

I've been testing maybe a dozen C2-ripped CD's without C2 now and results have been equal. The scratchiness of the CD's has varied, but it's been nothing severe.

But it looks like to me, that ripping a new, almost scratchless (1-2 light ones etc.) CD with C2 enabled never fails. And if you try a really damaged CD with C2, it will give a read error anyway.

But my Sony's C2 seems decent as long as the CD's not way overscratched and my LG's even better, it's just got that damn caching. What kind of experience does you guys (and gals ) have from your drives' C2?

A few questions about C2

Reply #1 –
The C1 and C2 (E11, E21, E12, E22 etc) error correction are completely performed by the drive, EAC can't do anything about it.

Secure mode without C2 reads twice and assumes that if the two reads are the same, then they are both correct.

Secure mode with C2 reads the drive flags for CU errors (unrecoverable) or C2 errors, and if it is on, it rereads until a majority of readings are the same.

When we talk about C2 accuracy, C2 working or not, we're discussing if the drive flags all CU errors, not if it reads the CD properly. Check the hydrogenaudio FAQ for "How to test C2 accuracy" in the "secure mode" section.

The second checkbox of the old version is an utter mess. I widely spread the false information that it would attempt to declick errors that were uncorrectable by EAC (no majority emerges from the rereads), while according to a recent mail from Andre Wiethoff, it just rereads until no CU or C2 is returned (the same flag sometimes show C2 errors, sometimes CU, according to the drives), instead of searching for a statistical majority. Thus it would just be the equivalent of Plextools.
I sincerely apologize for all that followed my EAC forum posts about this.

I've just bought a CDS200 CD for testing it. After deleting the registry key, installing, and checking secure mode, no cache, C2, no use of C2, it behaves as Andre described if "use C2" is checked. But after this, no way to get it back. All extractions rereads until a majority is found, whether the "use C2" box is checked or not !
I can get it to use C2 for correction only if I delete the registry key, cancels the wizard, go to drive options, check secure, no cache, C2, no use C2 (if I directly check use C2 it doesn't work). Actually, it seems to work as long as no registry key is created for the drive...
 

A few questions about C2

Reply #2 –
Quote
I widely spread the false information that it would attempt to declick errors that were uncorrectable by EAC (no majority emerges from the rereads), while according to a recent mail from Andre Wiethoff, it just rereads until no CU or C2 is returned (the same flag sometimes show C2 errors, sometimes CU, according to the drives), instead of searching for a statistical majority. Thus it would just be the equivalent of Plextools.

Sounds interesting. Do you happen to know why Andre removed this option, after all?

...apart from 'no time to further develop