HydrogenAudio

CD-R and Audio Hardware => CD Hardware/Software => Topic started by: Mac on 2003-05-01 21:25:45

Title: EAC's CRC
Post by: Mac on 2003-05-01 21:25:45
This is a question based on something I vaguely remember reading on a topic I can no longer find with search

I remember somebody saying you can check the quality of your cd rip by comparing your CRC's with those of other users who have submitted their values to a database.  Once two identical readings are acquired, they are taken as the correct values - so you can check you have the right ones too..

Does this exist, and if so where?  I can't find anything with google or in EAC itself.

Thanks
Title: EAC's CRC
Post by: kritip on 2003-05-01 21:28:33
If all offsets etc. were the same, then yes, it should be possible to impliment a database but none exist for this purpose at the moment.

If you want to rip and have it verified via others rips, then accurate rip is the way to go, then again that only  offers a good or bad status and no correction.

Wait a while, and im sure their technologies will merge!!

Kristian
Title: EAC's CRC
Post by: Pio2001 on 2003-05-01 22:14:09
To verify a rip against another is done comparing CRCs. It's not possible (and illegal) to download the 700 MB of reference data in order to check it against one's own extraction. Accuraterip corrects offsets.

http://www.accuraterip.com/ (http://www.accuraterip.com/)
Title: EAC's CRC
Post by: spoon on 2003-05-01 23:35:15
Unfortunately the CRCs shown in AccurateRip do not correspond with CRCs created by EAC, anyhow - I hope to wrap up accuraterip (as in finalize it, much has been learnt since it began) in the next few months then offer it to the other CD rippers, including EAC.
Title: EAC's CRC
Post by: Pio2001 on 2003-05-01 23:41:33
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I hope to wrap up accuraterip (as in finalize it, much has been learnt since it began) in the next few months then offer it to the other CD rippers, including EAC.

To include the AccurateRip CRC database so that EAC can check rips against other user's ones ?
That would be great !
Title: EAC's CRC
Post by: Mac on 2003-05-02 10:54:42
Heheh, I thought it would be legal to download 700mb of data to check your rip out - you already own the cd if you're ripping it..  unless it's not your cd

Accuraterip databases in CDex would be awesome (i prefer cdex...)    So far as I can tell, EAC and CDex give me the same results (i tend to rip twice to check) - there are only differences in the offsets as you say.
Title: EAC's CRC
Post by: liekloo on 2003-05-02 15:42:44
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... then offer it (accuraterip) to the other CD rippers, including EAC.

Wow! Not bad at all!!  B)
Title: EAC's CRC
Post by: Volcano on 2003-05-02 19:58:14
spoon:

Quote
Unfortunately the CRCs shown in AccurateRip do not correspond with CRCs created by EAC [...]


Why's that?


Mac:

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So far as I can tell, EAC and CDex give me the same results (i tend to rip twice to check) - there are only differences in the offsets as you say.


Wait a minute - you're saying that EAC and CDex produce different offsetted rips? Unless you're using offset correction in EAC, that seems pretty much impossible to me. (Are you sure CDex isn't b0rking your rips, as it is often the case? )
Title: EAC's CRC
Post by: liekloo on 2003-05-02 20:22:21
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spoon:

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Unfortunately the CRCs shown in AccurateRip do not correspond with CRCs created by EAC [...]


Why's that?

EAC uses a 32 bit sum ( = 8 hexadecimal characters ), which is not that accurate, especially not for huge files such as WAVs. For a thing such as AccurateRip a 'waterproof' checksum is really a must, that's why AccurateRip uses an alternative, more advanced checksum (Spoon made it by himself, if I am not mistaken)
Title: EAC's CRC
Post by: Mac on 2003-05-02 21:57:40
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Wait a minute - you're saying that EAC and CDex produce different offsetted rips? Unless you're using offset correction in EAC, that seems pretty much impossible to me. (Are you sure CDex isn't b0rking your rips, as it is often the case? )

Well...  CDex appears to include the gaps in files, whereas EAC doesn't.  I haven't changed anything in EAC, I don't dare to, I set it up to be accurate rather than fast on startup and left it at that.

When ripping off a dirty cdr, EAC's compare wave option gave different results for every track.  It said 683 samples were missing at the beginning of the CDex file, and 2005 were missing at the end of the EAC rip (for example)...

It also told me there were 200 or so different samples in a few of the waves... so I checked it out by subtracting one from the other..  it appears that the last 200 samples of the file tend to differ by 1. 

I've only occasionally had CDex make a bad file, and on those times it either ripped correctly the 2nd time round, or asking EAC to rip was pointless because the program hung
Title: EAC's CRC
Post by: ibm2080 on 2003-05-05 17:37:11
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I've only occasionally had CDex make a bad file, and on those times it either ripped correctly the 2nd time round, or asking EAC to rip was pointless because the program hung

How do you check that CDex created a bad file? Are you talking about the status X?