How Accurate is Comparison Ripping?

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How Accurate is Comparison Ripping?

Post by nathanh » Sat Jun 10, 2006 1:58 am

My novice understanding of the various ripping techniques are
  • * Comparison ripping (also called copy-test ripping) where multiple copies are made and compared. Max makes 3 copies by default, reading dummy sectors in-between reads to defeat drive-caching.
    * Jitter correction, waiting for the drive to report a error then "backing up", reading the sectors again, and aligning the bits so they perfectly overlap.
    * Reading the C2 error code information directly off the disc and making sure the checksums all match up.
Based on information I've read that Jitter Correction is unreliable with caching drives (which I have) and because nothing on the Mac supports C2 error correction, I'm using Max with Comparison Ripping. However I'm still getting pops and clicks on some CDs.

An example is Northern Exposure 2 Exp01. This is the single-track edition from the UK; the track is 1:12:31. Around 1:06:51 into the track there is a pop, followed by another pop about 2 seconds later, and then another pop about 2 seconds after that. However Max reported no errors during the rips nor during the comparison.

If the pops are being caused by the disc, is there any way for Max to tell me the disc has not been perfectly ripped? I wouldn't mind so much except Max didn't report any errors at all. If I knew there was an error I could pull out the polishing pads and try again, but without any errors there's no way for me to know about the pops except listening to every rip.

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Post by sbooth » Sat Jun 10, 2006 5:09 am

I am working on adding C2 error detection to the comparison ripper, which hopefully should help for damaged CDs by reporting when large errors were detected.

As far as not reporting errors, if the CD sector reads the same every time the comparison ripper will never report this as an error. The only method it uses to detect an error is by comparing multiple reads.

The comparison ripper doesn't perform any type of error correction currently. I hope to add this functionality in the future, though.

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