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Originally posted by Pio2001
When an error occurs, the C1 and C2 processes can recover exactly the info. This occurs inside the drive, and can't be accessed from outside.
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Ok, so my description was ok, except that the C2 correction happens inside the drive and not inside EAC.
EAC only checks for C2 success/failure flags and interpolates ('error concealment' as you put it) if drive reports C2 failure.
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EAC beta is the first soft that tries to simulate the error concealment, that is missing on the hard side, in the soft side. It interpolates the data when the C2 info says that an error wasn't recovered.
Andre could explain better, but I guess that isn't not very efficient yet,
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So, it's a new feature since 0.9b2 and it will get better, hopefully. Great!
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That doesn't tell if C2 works well. The point is to "test and copy selected tracks", not to "copy".
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So, I cannot test for C2 accuracy with just copy, because 'error concealment' in EAC may be able to deglitch/interpolate C2 unrecoverable errors.
Ok, I did as you suggested and tried the CD-Check disc again in my Sony UDD1621 with C2 ON (both checks in drive options). The results remain the same: Sony passes the test with flying colours in CRC, in EAC "copy ok" report and in audible quality.
To me this is a good indication that the C2 data is accurate.
Hitachi fails this same test miserably on all accounts while producing a high number of C2 errors to EAC: different CRC data, EAC reports "copy not ok" and ripped wavs sound horribly distorted.
Here are the complete results for my Sony UDD1621 dvd-rom with C2 on:
EAC extraction logfile from 17. March 2002, 21:30 for CD
Sony_UDD1621 / CD-Check C2 ON
Used drive : SONY DVD-ROM DDU1621 Adapter: 1 ID: 1
Read mode : Secure with C2, accurate stream, NO disable cache
Read offset correction : 594
Overread into Lead-In and Lead-Out : No
Used output format : Internal WAV Routines
44.100 Hz; 16 Bit; Stereo
Other options :
Fill up missing offset samples with silence : Yes
Delete leading and trailing silent blocks : No
Installed external ASPI interface
Track 1
Peak level 99.9 %
Track quality 99.9 %
Test CRC 03CA185B
Copy CRC 03CA185B
Copy OK
Track 2
Peak level 99.9 %
Track quality 100.0 %
Test CRC B601AA2C
Copy CRC B601AA2C
Copy OK
Track 3
Peak level 99.9 %
Track quality 100.0 %
Test CRC B601AA2C
Copy CRC B601AA2C
Copy OK
Track 4
Peak level 99.9 %
Track quality 99.9 %
Test CRC B601AA2C
Copy CRC B601AA2C
Copy OK
Track 5
Peak level 99.9 %
Track quality 100.0 %
Test CRC A6596AF8
Copy CRC A6596AF8
Copy OK
No errors occured
End of status report
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The fact that the wavs sound perfect is no proof. The C2 problems with the Hitachi GD-7500 are in fact completely unaudible.
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To me they are definitely not inaudible.
If you go back and read what I said, Hitachi GD-7500 (at least my drive) FAILS UTTERLY on the CD-Check test and the glitches are HORRIBLY AUDIBLE distortion on all the error test tracks (even the one with really small error stripe). You cannot go on without hearing these glitches, they are FAR from subtle.
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No idea... But everybody's talking about Toshiba
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I think everyone is talking about Toshiba, because it's good for copying copy-protected CD-roms. It reads sub-channel data alright, but it's not very fast (and it's noisy as hell as a drive).
Thanks,
Halcyon