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Topic: Is it worth fixing incorrect offset? (Read 680 times) previous topic - next topic
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Is it worth fixing incorrect offset?

I am in the process of cleaning up and reorganizing my digitized CD collection.  Last week I stumbled upon a few older rips splitted into tracks which were done a long time ago with grip (Linux). When retro verifying them with CUETools most of them are Accurately Ripped, but the offset clearly isn't correct.

My question is:
Is there any value in fixing the offset for archival purposes, or will it only bring a 'cleaner' accurip logfile and is it better to leave the rips as is? I don't intend to burn the files to a CDR btw.

I still have most of the original CD's stored in the attic as well, so a re-rip with modern software is also an option (albeit a bit cumbersome), therefore I am still curious about possible advantages (and risks if any) of fixing the offset manually with CUETools.

Re: Is it worth fixing incorrect offset?

Reply #1 –
If you still have the original disc it should be possible (even if it's damaged but still partially or mostly readable) to figure out what the offset is by analyzing a few working tracks and using that information to correct the offset of the existing rip made long ago.  If the entire disc is undamaged and works perfectly, a re-rip of the entire disc is usually much easier and simpler to do.

As for your question on whether or not it's worth it.  Well, that one is up to you.

Re: Is it worth fixing incorrect offset?

Reply #2 –
Quote from: Chibisteven on
If you still have the original disc it should be possible (even if it's damaged but still partially or mostly readable) to figure out what the offset is by analyzing a few working tracks and using that information to correct the offset of the existing rip made long ago.  If the entire disc is undamaged and works perfectly, a re-rip of the entire disc is usually much easier and simpler to do.
As for your question on whether or not it's worth it.  Well, that one is up to you.

It is quite easy to find the correct offset based upon the logfile created when retro-verifying the old rips. It would be nice to know if it's worth correcting this anyway or not.

Re: Is it worth fixing incorrect offset?

Reply #3 –
CUETools will not retro-verify against AccurateRip v2 unless the offset matches, so that makes for situations where offset fix will save you work. If a rip doesn't verify because v2 isn't match, and you find the offset in the logs, and you set it to verify against that offset - well if it verifies, you might have it write that in tags, and you will never have to retro-verify them again.
But say some don't have enough information in AccurateRip to verify - that is, not enough CDs submitted yet. Then - since you have already found what the offset is for that CD - you can convert with offset correction, and then upon later verification attempts you don't have to dig up that number.

If that is enough to make you want to do it.

You can also try https://www.dbpoweramp.com/perfecttunes.htm (from the creator of AccurateRip) - it does handle offsets also in ARv2.


Does offset correction do anything you should worry about?
Fixing offset will crop off some samples in one end and replace by zeroes in the other end. Often "both are zero in any case" making it indistingusishable.
And in case not, then typically they would be "tape hiss or dither" in the lead-in or lead-out, that is, they just didn't bother to silence completely what should be silence, so nothing substantial lost.
But if you still care: The samples that will be cut away, would never have been part of a "correct" rip anyway.

If the number is very large, then track boundaries could be off. But if track boundaries are audibly off, then they are likely "off by more than due to read offset, and for other reasons too", if that was precise enough: you cannot trust offset correction to fix it, you cannot even be sure it will go the right way. But if track boundaries are annoyingly off ... try! And listen.

Re: Is it worth fixing incorrect offset?

Reply #4 –
Thanks for you extensive explanation!
I already found out that AR v2 verification didn't work with wrong offsets.
What can be considered as a very large number? Most of the incorrect offsets over here vary from ~100 - ~600 samples, a few are ~1200 and I also have 1 or 2 with ~2000.

Re: Is it worth fixing incorrect offset?

Reply #5 –
There are many drives with offsets in the range 590 to 738, so that is not "much". There are a few in the 1100 to 1300 range too. https://daefeatures.co.uk/search/2
Recall that 1323 samples is still only 0.03 seconds.

I don't know how many different drives you could have used over the years.
Those offsets that are even higher could be a pressing with some strange write offset. Because the problem of different offsets also occurs upon writing, and I think most writers have different write and read offset. (Hence you usually cannot pin down "one correct offset from the artist's hand".)  It would sometimes happen that a pressing took a CD as "master" (i.e. ripped it).