Ivan X

Hello,

I have a suggestion regarding using the existing AccurateRip database with the newly discovered "corrected" offsets.

I'm a complete newbie to EAC, this forum, and the whole topic, but I decided I wanted to archive my CD collection so I have been doing a lot of reading about EAC, AccurateRip, dBpowerAMP, the forthcoming PerfectRip, etc. Fortunately, I'm technically inclined, so I've been able to follow most of it.

I'd like if you could please tell me where I am misunderstanding things here -- also, bear in mind that I haven't actually used any of this software yet, only read about it. (That's because I'm primarily a Mac guy, and my PC is at work.)

As I understand it, it has been determined (or at least well-theorized) that EAC's drive offset ratings are off by 30 samples (or 120 bytes, or 5 frames); that is, they indicate the absolute start of the audio to be 30 samples later than it actually is. Of course, this should make just about no difference to anyone except crazy purists such as myself, who can go ahead and add 30 samples from EAC's suggested read offset correction settings.

However, changing the EAC offsets makes AccurateRip not usable, because as the AccurateRip database of track extraction checksums is based on rips using the EAC offsets; that is, the checksum is based on tracks that are missing 30 samples at the beginning and contain 30 samples past the end of the track. Thus Andre has pointed out that it is too late to really start over with a new database, as it is that body of checksums which makes AccurateRip useful.

My thought: would it be possible to add the an option to EAC and/or
AccurateRip to actually create checksums based on the original EAC offsets, but then save to disk according to the "corrected" offsets? Then, the AccurateRip database could be used for confidence, but the user ends up with, well, an exact audio copy. And then, perhaps, a new checksum could be created from that and stored in a new field in the database, allowing AccurateRip to begin building a database of new checksums which already have a extremely high degree of confidence, because they've already been verified against the original offset checksums.

To spell this out a little more clearly:
- EAC adds two options: "correct 30-sample start offsets" and "use corrected offsets with AccurateRip" (or something like that)
- If set, then EAC will peform the rip based on the corrected offsets, plus read 30 more samples past the end (the lead-out?)
- AccurateRip calculates the checksum starting 30 samples in and adding 30 bytes past the end of each track
- AccurateRip reports the confidence level and submits to the database as usual
- optional: If there's confidence, then AccurateRip calculates a new checksum based on the corrected offsets, and submits that to a new field in the database; once this gets built up, AccurateRip can simply use it rather than checking the old one against the original EAC offsets.

If that all seems too unlikely, would it be possible to take a EAC bin/cue rip with the corrected offsets, and either a) rewrite the cue sheet so all the track positions are indiciated as five frames later, or b) remove the first 120 bytes from the bin, and append 120 nulls at the end, and then mount the image and run it though AccurateRip?

Thanks for your patience and help with this, and particular to Andre and Spoon and Carlos and Sidney and everyone else who's put so much time into figuring this all out and creating these great tools.

Ivan.