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Eli
post Mar 31 2010, 02:27
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I have only now become aware of Gregory S. Chudov's effort to develop CTDB (CUETools DB). I am very excited about this as I have actually been suggesting this to spoon (dbpoweramp's developer for over 5 years)

http://db.cuetools.net/about.php

for others that have missed it:
QUOTE
What's it for?
You probably heard about AccurateRip, a wonderfull database of CD rip checksums, which helps you make sure your CD rip is an exact copy of original CD. What it can tell you is how many other people got the same data when copying this CD. CUETools Database is an extension of this idea.
What are the advantages?

* The most important feature is the ability not only to detect, but also correct small amounts of errors that occured in the ripping process.
* It's free of the offset problems. You don't even need to set up offset correction for your CD drive to be able to verify and what's more important, submit rips to the database. Different pressings of the same CD are treated as the same disc by the database, it doesn't care.
* Verification results are easier to deal with. There are exactly three possible outcomes: rip is correct, rip contains correctable errors, rip is unknown (or contains errors beyond repair).
* If there's a match, you can be certain it's really a match, because in addition to recovery record database uses a well-known CRC32 checksum of the whole CD image (except for 10*588 offset samples in the first and last seconds of the disc). This checksum is used as a rip ID in CTDB.

What are the downsides and limitations?

* CUETools DB doesn't bother with tracks. Your rip as a whole is either good/correctable, or it isn't. If one of the tracks is damaged beyound repair, CTDB cannot tell which one.
* If your rip contains errors, verification/correction process will involve downloading about 200kb of data, which is much more than it takes for AccurateRp.
* Verification process is slower than with AR.
* Database was just born and at the moment contains much less CDs than AR.

How many errors can a rip contain and still be repairable?

* That depends. The best case scenario is when there's one continuous damaged area up to 30-40 sectors (about half a second) long.
* The worst case scenario is 4 non-continuous damaged sectors in (very) unlucky positions.

What information does the database contain per each submission?

* CD TOC (Table Of Contents), i.e. length of every track.
* Offset-finding checksum, i.e. small (16 byte) recovery record for a set of samples throughout the CD, which allows to detect the offset difference between the rip in database and your rip, even if your rip contains some errors.
* CRC32 of the whole disc (except for some leadin/leadout samples).
* Submission date, artist, title.
* 180kb recovery record, which is stored separately and accessed only when verifying a broken rip or repairing it.


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sauvage78
post May 10 2010, 08:06
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Well the two problems cases are very different:

- in the first problem case the AR database detects nothing wrong while the full checksum for the first track are different within the same pressing, this means that the problem is located inside the 5 frames ignored by AR.
This case have nothing to do with CTDB, I haven't tried CTDB on it, but I have deleted the bad doublons so I can't test anymore. Within all logic CTDB would have been of no help here because the difference being located ouside of the reach of the AR checksum it can only be located outside of the reach of the CTDB checksum (As CTDB ignores 5 added frames compared to AR.)

In this first problem case, I have only losslessly splitted the 5 first frames (as you've noticed it was painfull) & compared the Flac MD5 checksum which was different (The EAC wav comparator also detected differences). I cannot hear any difference (5 frames too too short to ABX anyway) & when I zoom on the 5 frames with any audio editor all I see is flat.

My first idea was naturally to think about a scratch, but I wasn't sure so I asked for advice & you told me that this was possibly due to an -472 offset problem due to overread. My skill with an audio editor to obtain the same result were too weak. But I think that the explanation is logic & I know how serious you can be so I tend to trust you.

But IMHO this second case is slightly different, maybe you're right & maybe this is an even bigger overread into the lead-in problem ... but as far as I understund the 5 frames ignored by AR are already there to avoid this kind of problem. So the problem is beyond the safety margin which means that this time it is more likely to be a simple scratch. I have already deleted the un-corrected file so I cannot verify (but even if I would still have it the first problem case showed that I didn't knew how to do)

Anyway all this doesn't really matter what I wanted to illustrate is that it is possible to have a scratch detected by AR by that cannot be corrected by CTDB because of the difference between the length of ignored frames.

QUOTE
Differences between pressings can vary by more than just the offset at the edges. For this reason, extending the area of what is ignored can actually be a good thing.


I know that pressings can vary by a lot more than just the offset, but I don't understand the second part of the sentence, I don't see why it would be a good thing to extend the ignored area when this area is already enougth. There is not offset bigger than 5 frames in the database & I even think that 4 frames is already enougth if you only judge by drive in the AR database. 1 frame is not a big deal & I know Spoon chosen 5 frames back when there was virtual drive with big offset in his database which have been purged. A 1 frame margin is also eventually good as an added margin. But Greg adds 5 more frames this sounds enormous to me, he simply doubled the margin of Spoon. I don't understand why so I just ask. Maybe I am wrong.

I admit I haven't investigated the EAC bug, but from what I understand of it, if it's just 2 reapeated frames at the end, it only pushes the margin down to 3 frames at the beginning, even in this case you really need an offset higher than 3 frames to get in trouble. Even with this bug I can understand a choice of 5+2=7 ... but going up to 10 is overkill. Even so, I don't think that bug should affect the technical choice behind CTDB.

I admit, it's easier to attribute it to a scratch wink.gif, but in this case it has a big chance of being a scratch IMHO.

This post has been edited by sauvage78: May 10 2010, 08:10


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CDImage+CUE
Secure [Low/C2/AR(2)]
Flac -4
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Gregory S. Chudo...
post May 10 2010, 08:46
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QUOTE (sauvage78 @ May 10 2010, 11:06) *
but going up to 10 is overkill.

You are forgetting that CTDB stores only one record for all pressings. Pressing offset adds to drive offset, and pressing offsets can be quite large. Even if drive offsets are limited to 4 sectors, pressing offsets of 6 sectors are not uncommon.


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CUETools 2.1.4
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Posts in this topic
- Eli   CUETools DB   Mar 31 2010, 02:27
- - Eli   For those that would like to see this added to dBp...   Mar 31 2010, 02:32
- - Eli   Chudov, What type of error correction are you usin...   Mar 31 2010, 17:50
- - Gregory S. Chudov   Of course CTDB is open, and the code required to u...   Mar 31 2010, 18:46
|- - Eli   QUOTE (Gregory S. Chudov @ Mar 31 2010, 13...   Mar 31 2010, 19:33
|- - Gregory S. Chudov   QUOTE (Eli @ Mar 31 2010, 22:33) Not for ...   Apr 5 2010, 12:15
- - Eli   Gregory, Thanks for the reply. Any thought of cha...   Apr 5 2010, 18:35
- - krafty   In the future, WILL THERE BE something that may de...   Apr 5 2010, 19:09
- - greynol   As I said elsewhere, consolidation is a good thing...   Apr 5 2010, 19:32
- - krafty   Well said, and if there was a way to identify thes...   Apr 6 2010, 00:15
- - Eli   A tool to scan audio for clicks/pops characteristi...   Apr 6 2010, 02:04
- - Eli   dBpoweramp forum CUETools DB thread QUOTE (Spoon;9...   Apr 8 2010, 00:11
- - Gregory S. Chudov   QUOTE (Eli @ Apr 5 2010, 21:35) Also, hav...   Apr 16 2010, 22:03
|- - Eli   QUOTE (Gregory S. Chudov @ Apr 16 2010, 17...   Apr 19 2010, 23:03
- - Gregory S. Chudov   We all benefit from CTDB support in as many applic...   Apr 20 2010, 11:06
- - Eli   spoon has said in the past that the majority of hi...   Apr 20 2010, 14:34
- - Eli   After my last post I thought about this some more....   Apr 20 2010, 15:50
|- - zfox   QUOTE (Eli @ Apr 20 2010, 17:50) After my...   Apr 20 2010, 16:03
- - Eli   Wouldn't change the software license at all. T...   Apr 20 2010, 17:25
- - zfox   That can be feasible even with GPL (dependency thr...   Apr 20 2010, 18:05
- - Eli   NP, I am sure you, zfox, would not mind providing ...   Apr 20 2010, 18:55
- - Teknojnky   methinks the record companies would have a little ...   Apr 20 2010, 20:09
|- - Eli   QUOTE (Teknojnky @ Apr 20 2010, 15:09) me...   Apr 20 2010, 21:55
|- - Gregory S. Chudov   QUOTE (Teknojnky @ Apr 20 2010, 15:09) me...   May 7 2010, 20:44
|- - Eli   QUOTE (Gregory S. Chudov @ May 7 2010, 15...   May 10 2010, 02:51
|- - Gregory S. Chudov   QUOTE (Eli @ May 10 2010, 05:51) Of cours...   May 10 2010, 07:38
- - zfox   QUOTE (Gregory S. Chudov @ Mar 31 2010, 20...   Apr 20 2010, 20:21
- - zfox   QUOTE (Teknojnky @ Apr 20 2010, 22:09) me...   Apr 20 2010, 20:26
- - Respwaned2   Hey, this is a great initiative. I always wondered...   May 7 2010, 17:01
- - sauvage78   Use encode in repair mode. It seems CTDB can dete...   May 7 2010, 17:28
|- - Respwaned2   QUOTE (sauvage78 @ May 7 2010, 16:28) Use...   May 7 2010, 19:11
- - sauvage78   1: Well I never had "Index out of range...   May 7 2010, 19:36
|- - Respwaned2   QUOTE (sauvage78 @ May 7 2010, 18:36) 1: ...   May 7 2010, 19:41
- - sauvage78   I never tried to submit myself (I wait to have a f...   May 7 2010, 20:15
- - Gregory S. Chudov   QUOTE (Respwaned2 @ May 7 2010, 22:41) It...   May 7 2010, 20:52
|- - Respwaned2   QUOTE (Gregory S. Chudov @ May 7 2010, 19...   May 7 2010, 22:05
|- - Gregory S. Chudov   QUOTE (Respwaned2 @ May 8 2010, 01:05) I...   May 7 2010, 23:51
- - Respwaned2   I've also got a "Exception: The specified...   May 7 2010, 23:51
- - Gregory S. Chudov   Maybe the output path (for the log) was too long -...   May 7 2010, 23:59
- - odyssey   How do I submit a rip to CTDB??? I tried Cueripper...   May 8 2010, 13:13
- - Fandango   I guess it is submitted when the rip is done... @...   May 8 2010, 16:10
- - Gregory S. Chudov   I don't store pregaps exactly because they are...   May 8 2010, 17:19
|- - Saxo   QUOTE (Gregory S. Chudov @ May 8 2010, 17...   May 17 2010, 14:25
|- - Fandango   QUOTE (Saxo @ May 17 2010, 15:25) I have ...   May 17 2010, 17:10
||- - Saxo   QUOTE (Fandango @ May 17 2010, 18:10) QUO...   May 22 2010, 17:46
|- - Gregory S. Chudov   QUOTE (Saxo @ May 17 2010, 17:25) In my o...   May 22 2010, 18:07
- - odyssey   I just ripped a few CD's that should not be in...   May 8 2010, 23:03
- - Gregory S. Chudov   You can easily check if CD is in database - when y...   May 8 2010, 23:41
|- - odyssey   QUOTE (Gregory S. Chudov @ May 8 2010, 23...   May 9 2010, 00:16
|- - odyssey   QUOTE (Gregory S. Chudov @ May 8 2010, 23...   May 9 2010, 00:32
- - Gregory S. Chudov   Select encode mode, and select 'repair' fr...   May 9 2010, 00:21
- - sauvage78   While I agree that burst rip should be accepted as...   May 9 2010, 04:12
|- - Gregory S. Chudov   QUOTE (sauvage78 @ May 9 2010, 07:12) The...   May 10 2010, 07:55
- - sauvage78   I only post an interesting log that I just found i...   May 10 2010, 03:51
- - greynol   The last time you claimed "damage due to a sc...   May 10 2010, 06:43
- - sauvage78   Well the two problems cases are very different: -...   May 10 2010, 08:06
|- - Gregory S. Chudov   QUOTE (sauvage78 @ May 10 2010, 11:06) bu...   May 10 2010, 08:46
- - greynol   Offset differences between pressings can be far gr...   May 10 2010, 08:10
- - sauvage78   Yes, your exemple made me realize that the more th...   May 10 2010, 08:57
|- - greynol   QUOTE (sauvage78 @ May 10 2010, 00:57) So...   May 10 2010, 17:53
- - Fandango   Is CTDB able to identify null sample tracks? AR fa...   May 10 2010, 18:37
|- - greynol   QUOTE (Fandango @ May 10 2010, 10:37) I m...   May 10 2010, 19:01
- - Gregory S. Chudov   CTDB doesn't care about tracks and it doesn...   May 10 2010, 18:43
- - sauvage78   I have found one more strange log: An AR3 rip with...   May 12 2010, 03:50
- - Gregory S. Chudov   I was actually testing CUERipper on that disc My ...   May 12 2010, 03:59
- - sauvage78   Ok, Thks I have submitted this CD so that you ca...   May 12 2010, 04:10
- - Gregory S. Chudov   Thanks   May 12 2010, 04:12
- - sauvage78   I just re-checked this CD, now the reverse is happ...   May 12 2010, 05:51
- - Gregory S. Chudov   I purged the second entry completely. Before i did...   May 12 2010, 06:12
- - sauvage78   Ok, once more I was completly wrong about CTDB I...   May 12 2010, 06:58
- - sauvage78   Well maybe the biggest use would be for protected ...   May 22 2010, 18:27
|- - Saxo   QUOTE (sauvage78 @ May 22 2010, 19:27) In...   May 22 2010, 20:46
- - sauvage78   Saxo: I am not arguing about the usefullness of cu...   May 22 2010, 22:04
- - sauvage78   Hi Greg, In a discussion (that took a bad directio...   May 27 2010, 18:34
|- - Gregory S. Chudov   QUOTE (sauvage78 @ May 27 2010, 21:34) It...   May 27 2010, 19:57
|- - greynol   QUOTE (Gregory S. Chudov @ May 27 2010, 11...   May 27 2010, 20:32
- - greynol   You might want to go over this thread again since ...   May 27 2010, 18:48
- - sauvage78   Gregory: QUOTE It doesn't submit in Burst mode...   May 27 2010, 19:03
- - greynol   QUOTE (sauvage78 @ May 27 2010, 11:03) So...   May 27 2010, 20:15
- - Teknojnky   maybe cuetools / cueripper have grown, or about to...   May 27 2010, 20:33
|- - greynol   QUOTE (Teknojnky @ May 27 2010, 12:33) ma...   May 27 2010, 20:54
- - sauvage78   Thks for the answers. I am reassured that the issu...   May 27 2010, 20:40
|- - Gregory S. Chudov   QUOTE (sauvage78 @ May 27 2010, 23:40) Gr...   May 27 2010, 20:56
|- - greynol   QUOTE (sauvage78 @ May 27 2010, 12:40) Lo...   May 27 2010, 21:06
- - Fuki   Hi! I've been away for a while. Since the...   May 27 2010, 21:25
- - Gregory S. Chudov   It means that database only knows about a pressing...   May 27 2010, 21:38
- - Fuki   This rip has no data track... BTW What would be t...   May 27 2010, 21:48
- - Gregory S. Chudov   Has no data track, Accurately Ripped   May 27 2010, 21:50
- - Fuki   CUETools report this: CODECD-Extra data track leng...   May 27 2010, 21:58
- - sauvage78   greynol: QUOTE Hopefully you have them organized b...   May 27 2010, 22:08
|- - Saxo   QUOTE (sauvage78 @ May 27 2010, 23:08) Ev...   May 28 2010, 15:57
|- - Fuki   QUOTE (Saxo @ May 28 2010, 15:57) QUOTE (...   May 29 2010, 18:05
- - sauvage78   Fuki: If I were Greynol I would say that "th...   May 27 2010, 22:24
|- - Goratrix   QUOTE (sauvage78 @ May 27 2010, 23:24) Mo...   May 28 2010, 14:30
- - Fuki   Tnx sauvage78! Like a lot of the rips I have o...   May 28 2010, 08:59
- - spoon   >I store the drive model and ripper version so ...   May 28 2010, 09:29
|- - Fandango   QUOTE (spoon @ May 28 2010, 10:29) Unfort...   May 28 2010, 13:46
- - sauvage78   Goratrix: I already asked Greg for such a feature ...   May 29 2010, 06:30
- - sauvage78   Saxo: Actually I still use EAC, so what I am criti...   May 29 2010, 07:56
- - greynol   This topic is about the CUEToolsDB, not about conf...   May 29 2010, 18:13
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