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View Full Version : AccurateRip CRC "confidence" rating and other CRC questions



msheridan
08-18-2015, 12:10 PM
Hi,

I noticed something today using the CD Ripper and wanted to ask about the practical implications.

I have a disc that ripped all tracks just fine, except one (out of 19 tracks). So, I ejected the disc and cleaned it as this has lead to success in other cases. However, the disc ripped to the same CRC: Inaccurate but Secure. I tried a couple of more times, same result.

After each rip, the "confidence level" decreased - the AccurateRip comparison was taking each rip attempt from me, and counting each as a unique submission (but a submission that matched my seemingly inaccurate CRC). I think I managed to attempt 3 or 4 tries in total. Since this particular track had over 80 other submissions, its unlikely to impact the perceived accuracy of results for other users. But - for tracks with low submissions, seems this would be more of an issue. Also, doesn't this imply that if someone wanted they could flood the AccurateRip DB with inaccurate CRCs - giving faulty results for everyone?

Seems that the DB should identify more than just submissions. Might it be more useful and potentially more accurate if it could identify something along the line of unique user rip CRCs? So - if I get the same CRC from 10 rip attempts - I only show up as 1 submission in the DB. But, if I got two different CRCs for the same track (obviously from different rip attempts), then that would count as 2 submissions.

How is the CRC calculated? Is the CRC based only on the data read from the original disc? If I trip a track to WAV with ID3tag data included, will that result in the same CRC as a rip of the same track to WAV w/out ID3tag info stored in the file? Can a CRC be calculated from a ripped file alone?

Should the CRCs from other software that support AccurateRip technology be comparable to those generated with CD Ripper? If another software lists a CRC of (made up for example) AAAA and CD Ripper lists a CRC of BBBB - then, wouldn't one of them have to be inaccurate? What if they both claim to be accurate rips?

Spoon
08-19-2015, 04:04 AM
Your submissions would never change a confidence level, unless they match, then the confidence is added to.

What you are possibly seeing is a miss-match and one of the alternative pressings being used for display.

msheridan
08-19-2015, 05:18 AM
The confidence level started at 83 or 84, and went down to 80 - so the confidence level did change, right?

It went down by one, with each additional rip.

Spoon
08-19-2015, 02:38 PM
Your submissions would only change the confidence after 1 month when the database is rebuilt, it is not possible for it to act as you describe.