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Topic: AccurateRip Also Helps to Insure Error Free Single Track Rips?  (Read 1256 times) previous topic - next topic
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AccurateRip Also Helps to Insure Error Free Single Track Rips?

Besides the fact that AccurateRip cannot guarantee error-free extractions, I thought that I read somewhere that it can only boost the likelihood of error free CD track rips if you rip the entire CD. So to trying learning the truth I posted here https://forum.dbpoweramp.com/showthread.php?46626-%93New-amp-Improved%94-AccurateRip

But I’ve yet to receive a definitive answer. Yes or no?

Please note numerous other questions:

Why, where, when and how CRC numbers are generated?

How and what software to use for comparing them?

Does comparing two CRC numbers generate a checksum?

Why and how are checksums useful?

What is Secure Mode and if it’s necessary with AccurateRip?

What are “tags” and how to use them to use AccurateRip for ripping
CD tracks error free?

Can I do all of the above just as easily and accurately in EAC or should I switch
to dbpoweramp or CDRipper?

If you rather not explain then I’d really appreciate links to tutorials for understanding all of this and more. 

Re: AccurateRip Also Helps to Insure Error Free Single Track Rips?

Reply #1 –
There are 2 problems when ripping a CD.
A CD doesn’t contain information about the content.
Bit perfect reading is not guaranteed by design.

Before you can compare a locally calculated checksum with one in a internet database, you have to identify the track.
Unfortunately a CD doesn’t have an ID.
A common solution is take the number of tracks and their length.
This in general is enough to identify the CD correctly.
So you need the TOC of the whole CD for identification.
Once it is identified, the meta data is added (Album, artist, cover art, etc)
This is stored in tags.
Tags are pieces of information stored in the audio file so media players can identify a track and display the information in a interface.
As the CD is identified, we can rip the whole or a single track, just as you please.
Each sample is used to calculate the checksum.
When all samples are read, this checksum is compared with the one in the AccurateRip database.
Basically you compare your rip with those of others.
If many users generate the same checksum, the likelihood this to be the right value increases.
Bit more detail on my website
https://www.thewelltemperedcomputer.com/Intro/Ripping.htm
https://www.thewelltemperedcomputer.com/TG/Tagging.html
https://www.thewelltemperedcomputer.com/KB/AccurateRip.htm
TheWellTemperedComputer.com
 

Re: AccurateRip Also Helps to Insure Error Free Single Track Rips?

Reply #2 –
@nmxny24 :

It seems to me that over at the dBpoweramp forum, you got two different answers to two different questions.
Yes you can insert a CD, rip one single track and verify it with AccurateRip upon ripping. But if you have an already-ripped single track in a single file, it is harder to find.
AccurateRip is tracks-based, but it needs to know what CD the track is from. If you have let dBpoweramp read the CD TOC then it knows. Also if you upon ripping let dBpoweramp write CDTOC to a tag - or AccurateRip ID to a tag - then it will also be known what CD it is from, and then a single track can be retro-verified.

Then you asked what "tags" are? They are the metadata (non-audio) information. Like, if your mp3 or FLAC file says the artist is "Black Sabbath", then that is a tag. dBpoweramp can also write to tags information about what CD the track was taken from, and then the PerfectTunes application from the same manufacturer will be able to retro-verify a lossless rip of a single track.


The checksum is generated from the rip and then compared to one stored in a database. Comparing those are easy.
You don't really need to know what the checksum is and how it is calculated. It suffices to know that if there is a wrong frame (= chunk of samples), the likelihood of still getting the same checksum is negligible; if the checksum matches the one already stored, then you are as sure as necessary that your rip matches someone else's rip, and that does not happen by coincidence: if you and I get the same result on two physical copies of the same CD release, then both of us are correct.

AccurateRip does have some limitations. It does not check the very beginning/end, as there is something called "offset" meaning that some drives will start and end some samples later. So if you have an error there and only there, it won't be part of the checksum. And it cannot safeguard against pressing errors - if the wrong bits end up on the CD then it cannot tell that the bits are wrong (and there are longer stories to be told about this, but I'll keep it at a non-technical level).


Secure mode? You don't need secure mode if the rip verifies as accurate. If it doesn't, then secure mode might help to get the bits right. If you use dBpoweramp, it switches to secure mode only after having tried burst with AccurateRip verification, you don't have to switch yourself. EAC or CUETools on the other hand, will do all the ripping first and check AccurateRip afterwards (IIRC).