[bigshot]

I think that may be a problem that isn’t very common as optical drives have gotten better.

 

[bfreedma]

I think that may be a problem that isn’t very common as optical drives have gotten better.

What’s being tangentially discussed is drive offset, which isn’t related to the quality of the optical drive. It’s variable based on the hardware and how the drive initially positions the head. While drive offset won’t typically impact individual tracks, it can result in leading or trailing bits being added to the rip. If this happens, the file will technically not be an exact copy.

Setting the drive offset for your drive/system largely eliminates this.

Warning - small sample size based comment below.

I ripped 100 CDs without sitting the offset and 9 of them failed the copy comparison. After setting the offset, zero failed. This had no impact on the playback that I could determine, as the padding is small enough to not cause subjectively identifiable delay.

It’s probably only a real concern for someone archiving master copies. That said, it’s a one time set and forget function if your ripping software supports it.

https://www.exactaudiocopy.de/en/index.php/overview/basic-technology/offset-technology/

 

[bigshot]

I’ve never adjusted my drive. I wouldn’t know how to do it. Don’t they come properly aligned, and doesn’t the laser have some flexibility in tracking? I seem to remember hearing that in the early days of CDs.

 

[Roseval]

I’ve never adjusted my drive

You can't as it is a property of the optical drive.
However, if you submit your rip to AccurateRip, an at itself totally insignificant difference in offset will yield a different MD5.
Hence the offset correction.

 

[Crypt Keeper]

Ez cd audio converter available for free on torrent trackers.

 

[bfreedma]

I’ve never adjusted my drive. I wouldn’t know how to do it. Don’t they come properly aligned, and doesn’t the laser have some flexibility in tracking? I seem to remember hearing that in the early days of CDs.

The offset is part of the manufacturing process and isn’t mechanically adjustable. The software based offset correction enables the various offsets to be standardized. Early CD issues were mostly tracking problems.

This isn’t a matter of tracking and all drives of the same model will have the same offset. The laser starts reading at a specific point of the CD, so flexibility isn’t going to solve the “issue” - the laser is starting where the hardware expects the first byte of the read to be. Unfortunately, there is some variability in drive geometry - the offset adjusts the read to the correct position.

To be clear, this won’t impact bit perfect reads, but it does lead to slightly different files with trailing or leading padding of a handful of bits. It’s not something that a typical consumer needs to worry about, but if an absolutely identical file is required for archiving, the offset needs to be considered.