Accuraterip ... AR but maybe damaged, A question for Spoon/Gregory/Greynol Options

[sauvage78]

Hi, I just searched for doublons/clones in my flac collection with cuetools & CloneSpy (a clone finder software) & I happened to find something strange: a clone with an overall different checksum (so technically CloneSpy doesn't detect it as a clone) [Edit: My collection is only made CDImage.flac] but with all matching checksums against the accuraterip database & with a very high confidence for all tracks. So the data is obviously the same ... but there is a problem: the CRC for track 1 with or without silence at the end of the log doesn't match, hence the overall checksum difference & the non detection as an exact clone by CloneSpy. So my question is: am I right to interpret this situation as a non-detected scratch (or truncated audio) in one of the 2 rips ? I mean a scratch (or truncated audio) located in the 5 first frames of the rip which accuraterip might ignore ? (I know AR ignore the last 2940 samples but does it also ignore the first 2940 samples which might be the problematic part in my case). Is my interpretation of the problem right ? or is there another explanation ?

Here is a copy/paste zoom in the problematic part of the logs:
Log1: All tracks accurate

CODE

Track    [ CRC32  ]    [W/O NULL]    
--    [BB8A18D4]    [C665239A]    
01    [52E2E723]    [303E0CCB]

Log2: All tracks accurate same checksums for individual tracks in the beginning except at the end:

CODE

Track    [ CRC32  ]    [W/O NULL]  
--    [C96571CF]    [212E440F]    
01    [D84FE9DB]    [13FF4095]

Here are the full cuetools logs:

CODE

[Verification date: 19/04/2010 22:51:27]
[Disc ID: 0014baf9-00b63a6b-a20c650b]
Track    [ CRC    ] Status
01    [56227f15] (130/227) Accurately ripped
02    [1a28dd82] (129/226) Accurately ripped
03    [6116e989] (128/224) Accurately ripped
04    [1ee3eb35] (130/226) Accurately ripped
05    [9b0f8709] (129/226) Accurately ripped
06    [6731bd99] (129/224) Accurately ripped
07    [2127ab0e] (130/225) Accurately ripped
08    [d6d7a06d] (129/223) Accurately ripped
09    [0940c3c4] (129/223) Accurately ripped
10    [9f0066c1] (131/224) Accurately ripped
11    [b372f2be] (127/219) Accurately ripped
Offsetted by -669:
01    [24323cd0] (92/227) Accurately ripped
02    [ee621a53] (95/226) Accurately ripped
03    [085e2055] (94/224) Accurately ripped
04    [3887918a] (94/226) Accurately ripped
05    [527338a1] (95/226) Accurately ripped
06    [1326e7e5] (93/224) Accurately ripped
07    [5c9d3731] (90/225) Accurately ripped
08    [212cde25] (89/223) Accurately ripped
09    [55786f8a] (92/223) Accurately ripped
10    [d05af285] (88/224) Accurately ripped
11    [344ff140] (87/219) Accurately ripped
Offsetted by -664:
01    [c47bf19e] (02/227) Accurately ripped
02    [1f296cf7] (02/226) Accurately ripped
03    [e964ac04] (02/224) Accurately ripped
04    [1c74678b] (02/226) Accurately ripped
05    [447707e9] (02/226) Accurately ripped
06    [2daa732f] (02/224) Accurately ripped
07    [06726fee] (02/225) Accurately ripped
08    [855005de] (02/223) Accurately ripped
09    [84fdb1e5] (02/223) Accurately ripped
10    [e48a9fd2] (02/224) Accurately ripped
11    [a0d957ca] (02/219) Accurately ripped

Track    [ CRC32  ]    [W/O NULL]    
--    [BB8A18D4]    [C665239A]    
01    [52E2E723]    [303E0CCB]    
02    [3898BA23]    [EC67745A]    
03    [298AA727]    [B5195132]    
04    [E1B43F46]    [CFA333F1]    
05    [2B362BD5]    [BCA7E87C]    
06    [A7D2A800]    [54FD2C90]    
07    [9FB44339]    [6E321D61]    
08    [C256DF0E]    [A744BA17]    
09    [721A93ED]    [643A858C]    
10    [380C3FD2]    [8B338E6B]    
11    [9B821032]    [E0D42D60]

CODE

[Verification date: 19/04/2010 22:56:03]
[Disc ID: 0014baf9-00b63a6b-a20c650b]
Track    [ CRC    ] Status
01    [56227f15] (130/227) Accurately ripped
02    [1a28dd82] (129/226) Accurately ripped
03    [6116e989] (128/224) Accurately ripped
04    [1ee3eb35] (130/226) Accurately ripped
05    [9b0f8709] (129/226) Accurately ripped
06    [6731bd99] (129/224) Accurately ripped
07    [2127ab0e] (130/225) Accurately ripped
08    [d6d7a06d] (129/223) Accurately ripped
09    [0940c3c4] (129/223) Accurately ripped
10    [9f0066c1] (131/224) Accurately ripped
11    [b372f2be] (127/219) Accurately ripped
Offsetted by -669:
01    [24323cd0] (92/227) Accurately ripped
02    [ee621a53] (95/226) Accurately ripped
03    [085e2055] (94/224) Accurately ripped
04    [3887918a] (94/226) Accurately ripped
05    [527338a1] (95/226) Accurately ripped
06    [1326e7e5] (93/224) Accurately ripped
07    [5c9d3731] (90/225) Accurately ripped
08    [212cde25] (89/223) Accurately ripped
09    [55786f8a] (92/223) Accurately ripped
10    [d05af285] (88/224) Accurately ripped
11    [344ff140] (87/219) Accurately ripped
Offsetted by -664:
01    [c47bf19e] (02/227) Accurately ripped
02    [1f296cf7] (02/226) Accurately ripped
03    [e964ac04] (02/224) Accurately ripped
04    [1c74678b] (02/226) Accurately ripped
05    [447707e9] (02/226) Accurately ripped
06    [2daa732f] (02/224) Accurately ripped
07    [06726fee] (02/225) Accurately ripped
08    [855005de] (02/223) Accurately ripped
09    [84fdb1e5] (02/223) Accurately ripped
10    [e48a9fd2] (02/224) Accurately ripped
11    [a0d957ca] (02/219) Accurately ripped

Track    [ CRC32  ]    [W/O NULL]    
--    [C96571CF]    [212E440F]    
01    [D84FE9DB]    [13FF4095]    
02    [3898BA23]    [EC67745A]    
03    [298AA727]    [B5195132]    
04    [E1B43F46]    [CFA333F1]    
05    [2B362BD5]    [BCA7E87C]    
06    [A7D2A800]    [54FD2C90]    
07    [9FB44339]    [6E321D61]    
08    [C256DF0E]    [A744BA17]    
09    [721A93ED]    [643A858C]    
10    [380C3FD2]    [8B338E6B]    
11    [9B821032]    [E0D42D60]

Note:
The album is Pantera - 1992 - Vulgar Display Of Power original pressing
& I know that:

CODE

Track    [ CRC32  ]    [W/O NULL]    
--    [BB8A18D4]    [C665239A]    
01    [52E2E723]    [303E0CCB]

is the good checksum if one of the 2 is bad. (I compared my own rip with several 3rd party rips as I own the CD ... it's one of the best heavy metal album of all time)

So the question is not which one is the good rip but rather what is happening technically & why a rip which, at first look, is perfectly accurate rip is in fact maybe damaged.

I am worried because it was one of the very first doublon I found ... so it might not be such an exception ... I am scarred to search further now ...

Edit: By the way, we need an april update of the database Spoon

This post has been edited by sauvage78: Apr 19 2010, 22:44

[sauvage78]

I have uploaded the 5 first frames of the 2 rips (Track 1) here

The result looks flat/silent in Audacity but the flac MD5 checksum in F2K is different so I guess that being flat in Audacity doesn't always mean silence, specially if the noise is almost zero.

I don't know how to achieve this in Audacity:

You should really inverse paste one onto the other and zoom in on the difference to see if there is any.

my skill with Audacity is very limited, basically I only use it to cut/shorten samples when I when I want to run an ABX test.

Thanks for trying to help.

Edit:
For me it looks more & more like a very small scratch within the 5 first frames which makes me wonder if 4 frames/2352 samples wouldn't be a better number than 5 frames/2940 samples for the beginning/end ... specially as the huge majority of drives (seems all) have an offset below 2000 samples.

Personnaly I don't really care if a few exotic drives cannot be used with Accuraterip if it slightly strengthen the confidency of all the other rips in the world. But I agree 1 frame will not solve the problem anyway...

The drive with the biggest offset in the database seems to be:
ASUS - CD-S480-A5 +1776
which means that 4 frames/2352 samples would be enough ... & with a good margin. (2352-1776=576=almost 1 frame of margin already)

5 frames seems more & more overkill to me. It's 1 frame of verification lost in the beginning & another one lost in the end for no real gain/safety compared to the drive offset list.
I know 2 frames is ridiculously small, but still ... it seems that my exemple shows that bad thing can happen within this 2 frames ... as small as those can be.

Edit 2: (Found a bigger offset in the database)

This post has been edited by sauvage78: Apr 20 2010, 16:23