Offsets [EAC]

what’s the read & write offsets for the LTR-48125W? does anybody know…

btw do offsets have an effect on the quality of the rip?

Nearly all drives have a read/write offset (except the new LiteOn 52246S which has a perfect 0 offset).

Your LiteOn model that I have tested on a friend of mine has an offset of 24 bytes (6 CD audio samples, because 1 sample=4 bytes). You can test the offset by using EAC or Nero CD Speed and making a test disk.

The offset is to do with the drive itself with the shifted reading/writing position from the CD/CDR/CDRW.

When your drive is asked to read an audio CD and it is to read sector 0, it doesn’t exactly give samples from the beginning, it instead starts 24 bytes ahead of the beginning of that sector, so yes you will be missing some bytes of music. Also, because of this offset you will be having some extra bytes from the leadout added to the end of the last track as well. But it is so small that you won’t notice the difference. This means that the copy will not be a 1:1 copy. It gets worse, the drive does the same thing when writing but it has a different offset. To read the missing bytes the drive need to be able to read into the ‘pregap’ and the ‘leadout’.

EAC has the ability to correct the problem - I’m not sure how this works, but you need to find out the read and write offsets in samples first and then enter them into the drive options.

Of course this does n’t affect the quality of rip - only the problem is missing small bytes from start of each track.

This only applies to audio CDs not data CDs, because the drive corrects itself using the CDROM sector sync headers.

Usually, the first and last several thousands bytes of the audio track are silent, so it’s not a problem.

Truman,
So are you saying that the new 52X Lite-On doesn’t need offset correction? Meaning… if there is no problem CD, you don’t need EAC for a perfect rip?

Robert

@valnar, yep. But as Pio2001 said, you’re not missing much or just silence from most CDs - which I agree. Unless you want absolute 1:1 perfect rips.

Originally posted by Truman
Nearly all drives have a read/write offset (except the new LiteOn 52246S which has a perfect 0 offset).

Are you talking about a read offset of 0 or a write offset of 0 (or both, which would be the best, of course) ?

Both, a read and write offset of 0.

A read/write offset of 0?!? I have read nothing but good things about lite-on drives on these forums, but now this?!? :eek:

This has me seriously thinking about getting a Lite-On drive to go with my PlexWriter. – Do Lite-On drives have perfect C2 error reporting like plextors do?

I just ordered a Plextor, but knowing the Lite-On needs no offset correction may make me return it. However, Plextors burn quality is still better, and audio CD’s is what I care about.

Robert

You still need EAC for the secure mode. Bad source, clicks and pops are 50% of the problems encoutered in copies. The other 50% are coasters. I have never heard about any problem caused by an offset since the two years I’m in EAC discussions.

Plextors have perfect C2 reporting with Plextools only. EAC can’t get perfect C2 from them. It is maybe because Plextools use a special read command to access Plextor drives.
I don’t think EAC C2 reading is bugged, since a beta Nero CDSpeed used by CDRinfo, that was developed by Ahead, detects imperfect C2 on most drives too.

You still need EAC for the secure mode.

I understand that we still need to rip a CD in secure mode even if it is in perfect condition because the cd could have microscopic bubbles in it or other minor defects. But, are you recommending EAC’s secure mode over PlexTools C2 mode when using a new plextor drive?

I was under the impression that PlexTools is actually better than EAC because it can correct C2 errors (caused by minor CD defects) that EAC cannot… For instance, if a brand new CD has a very minor manufacturing flaw in it that causes a few pits in the cd to be read incorrectly, EAC would just read that sector incorrectly 2 times in a row and not detect the error, but PlexTools would detect a C2 error and actually fix the problem…

Is this true, or am I misinformed on this?

Bottom Line: Both EAC and PlexTools can correct read/write offsets and detect pre-track gaps, but which is the better program for making perfect audio cd backups?

Pio2001, you are obviously very knowledgeable about this stuff, and I appreciate your input :bow:

Originally posted by Truman
Your LiteOn model that I have tested on a friend of mine has an offset of 24 bytes (6 CD audio samples, because 1 sample=4 bytes). You can test the offset by using EAC or Nero CD Speed and making a test disk.

so i put in ‘24’ in the combined read/write offset, rite?

btw how do you find the read offset? i can’t seem to get it with any of my audio CDs.

thanks

Edit:

how do i use nero cd speed to get the offsets? by running Extra > advance DAE test > Create test cd, rite?

couldn’t get EAC to work

@webcrawler, EAC uses units in audio CD samples, so you should be using 6 not 24. Sorry, I didn’t make myself clear, this figure I’ve given is only the read offset.

By the way:

combined read/write offset = read offset + write offset

You need to find the write offset as well. Read the FAQ in the EAC website on offsets:

http://www.exactaudiocopy.de

There you can use a method to find out your combined read/write offset.

Originally posted by Dillweed
But, are you recommending EAC’s secure mode over PlexTools C2 mode when using a new plextor drive?

No. I’ve not got a Plextor drive, so I didn’t test Plextools myself, and I didn’t collect user reports. But from memory there were cases where EAC performed better, and cases where Plextools performed better.

Originally posted by Dillweed
I was under the impression that PlexTools is actually better than EAC because it can correct C2 errors (caused by minor CD defects) that EAC cannot…

That is true at least in theory. Plextools rereads bad parts, record the positions of good and bad samples, then reconstructs the part using all good samples that occured in any read. This way, taking what’s good in each read, the final result can be better than any of the readings. EAC can’t do this.
Plextools might be faster than EAC too, as it reliably uses C2, while EAC rereads everything if C2 is turned off for safety.